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JANUARY - DECEMBER 2018 VOL - 8, ISSUE - 1

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TRIVANDRUM

DENTAL JOURNALJOURNAL OF INDIAN DENTAL ASSOCIATION TRIVANDRUM BRANCH

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ISSN - 0976 - 4577Indexcopernicus ID No. 5365

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TRIVANDRUMDENTAL JOURNALJOURNAL OF INDIAN DENTAL ASSOCIATION TRIVANDRUM BRANCH


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CONTENTS

JANUARY - DECEMBER 2018 VOL - 8, ISSUE - 1

ORIGINAL ARTICLERole of Ultrasound in the diagnosis of maxillofacial swellings - A Clinical Study 4Twinkle S Prasad , Minu Sugathan, Anita Balan

CASE REPORTWhite Lesion on Tongue A Clinico Pathologic Conference 9Shabna Fathima S., Jincy Thomas, Sunila Thomas, Vivek Velayudhan Nair

REVIEWMicroarray Technology: Review, Applications And Future Prospects 14Roopan Prakash, Arun Mohan, Tharun Varghese Jacob, Manoj S Nair, Arun G Pillai

Tongue print: an undeniable proof in biometric authentication – A brief review 18Shali S. Nair, T.T Sivakumar, Anna P. Joseph, Varun B. R, Vinod Mony

Revisualising Esthetics - A Glance Into 4D Printing : A Literature Review 21Anu Mary Joy, Sangeeth K Cherian, Sudeep S

A Quest For Gold Standard In Implants 25Sreeja C Babu, Noxy George Manjuran, Sudeep S

TRIVANDRUM

DENTAL JOURNALJOURNAL OF INDIAN DENTAL ASSOCIATION TRIVANDRUM BRANCH


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Ultrasound and Nuclear medicine in medicalimaging, a new era of diagnostic understanding ofthe maxillofacial region has flowered, thoughsurgical biopsy is the time-honored primary standardfor tissue diagnosis1. Ultrasonography is a relativelysimple, noninvasive imaging modality especiallyuseful for superficial lesions. In the soft tissues ofthe head and neck, most swellings that present tothe clinician can be managed with maximalefficiency using ultrasound2. It is remarkablyaccurate and easier to perform than CT or MRI. Inmany cases, it provides a confident diagnosis beforeFNAC or histology, but in those cases where FNACor FNAB is indicated, Ultrasound is the imaging

Role of Ultrasound in the diagnosis of

maxillofacial swellings - A Clinical StudyTwinkle S Prasad1 , Minu Sugathan2, Anita Balan3

Introduction

Swellings of the maxillofacial region may bereactive, inflammatory, benign neoplasms, cysts, ormalignant tumors. The most common of these arepathologies of salivary glands, odontogenic lesionsand lymph nodes. With the arrival of CT, MRI,

Twinkle S Prasad , Minu Sugathan, Anita Balan

1Associate Professor, Department of Oral Medicine & Radiology, GovtDental College, Trissur.2Junior Resident, Dept of Oral Medicine & Radiology, Govt DentalCollege, Kottayam.3Professor & Principal, Government Dental College, Trivandrum.

Address for Correspondence:Twinkle S PrasadEmail: [email protected] of Publication: Original Research PaperConflicts of Interest: Nil

Trivandrum Dental Journal 2018 Vol 8, Issue - 1

Abstract

Background : With the arrival of CT, MRI, Ultrasound and Nuclear medicine in medical imaging, a newera of diagnostic understanding of the maxillofacial region has flowered, though surgical biopsy is thetime-honored primary standard for tissue diagnosis. Ultrasonography is a relatively simple, noninvasiveimaging modality especially useful for superficial lesions. It is remarkably accurate and easier to performthan CT or MRI. In many cases, it provides a confident diagnosis before FNAC or histology, but in thosecases where FNAC or FNAB is indicated, Ultrasound is the imaging technique of choice in guiding theneedle to its best target. It is nevertheless, operator dependent. The detail seen is superior to CT or MRI.However it is still underutilized in maxillofacial imaging. Objectives : 1. To analyze and study thesonographic features of maxillofacial swellings. 2. To correlate the ultrasound findings in maxillofacialswellings with histopathology and thus assess the accuracy of USS in the diagnosis of such swellings.Method : Fifty-six (56) patients with maxillofacial swellings, who attended the Oral medicine & Radiologyclinic over a period of one year, were selected for the study. After careful history taking & clinicalexamination, sonograms were obtained with high resolution real time scanner with an 8-11MHz lineararray scanner head. The provisional diagnoses obtained from clinical examination & ultrasound wascompared. Histopathological examination was done for the swellings and this diagnosis was taken as thegold standard for comparison. Results : Ultrasound was sensitive in diagnosing sialadenitis in 13 casesout of 15 cases. USS of the 9 cases of metastatic lymph node from squamous cell carcinoma showedpositivity for 6 cases. Ultrasound scan was 60% sensitive, 100% specific and 92.8% accurate for diagnosingmalignancy in maxillofacial swellings. Conclusion : Ultrasound scanning is a highly reliable non-invasivetechnique for rapid investigations of head & neck soft tissue swellings. It may be used as an adjunctiveprocedure for pre-surgical evaluation of swellings, especially when the relationship with adjacent anatomyposes a surgical dilemma. Ultrasound combined with FNAC is highly accurate due to the low prevalenceof non-diagnostic sampling in such settings.

Keywords: Ultrasonography, Dentistry, Maxillofacial swellings.

ORIGINAL ARTICLE

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technique of choice in guiding the needle to its besttarget. It is nevertheless, operator dependent.Ultrasound is gaining a lead role in maxillofacialswellings related to salivary glands, neoplasms,thyroid & parathyroid, larynx and site specificswellings, largely due to the increased spatialresolution achieved by the latest generation ofmachines and transducers. For thyroid nodules,ultrasound provides a more reliable diagnosis thanFNAC or scintigraphy3. With neck lymph nodes, itis possible to examine their vascularity, not onlywith color flow and power Doppler, but also with3D volumetric analysis. The detail seen is superiorto CT or MRI.

Aims

The present study analyses the various diagnosticfindings of maxillofacial swellings from a varietyof causes, by Ultrasound. These findings arecorrelated with the provisional diagnosis obtainedby detailed history and patient examination. Thehistopathology is done finally, for all cases.Radiological diagnoses obtained by plain filmradiography & CT (done in a representative numberof cases) is combined with the clinical diagnosis toarrive at a provisional diagnosis. The USS findingsare compared with histopathology. The accuracyof USS is assessed by standard statistical methods.

Objectives

1. To correlate the clinical & sonographicfindings in maxillofacial swellings withhistopathology and thus assess the validityof Ultrasound in the diagnosis of suchswellings.

2. To analyze and study the sonographicfeatures of maxillofacial swellings.

Materials and Methods

Fifty-six (56) patients with maxillofacial swellings,who attended the Oral medicine & Radiology clinicover a period of one year, were selected for thestudy. After careful history taking & clinicalexamination, ultrasound was done for the swellings.The provisional diagnoses obtained from clinicalexamination & ultrasound were compared.Histopathological examination was done for the


swellings and this diagnosis was taken as the goldstandard for comparison. Intrabony lesions andnodes of size less than 4mm were excluded fromthe study. Also excluded were the patients withsevere systemic illness, bleeding diatheses and whowere non-cooperative. The cases were collected atrandom with no preference given to age, sex or anyother criteria.

Technique of Ultrasound

Sonograms were obtained with high resolution realtime scanner with an 8-11MHz linear array scannerhead. The swellings were examined longitudinallyand transversely in a continuous sweep technique.Ultrasound findings were documented with specialreference to number, location, size, echo pattern& margins of the lesion. Special care was taken toassess the relation of the swelling to adjacentmuscles and vessels, especially for lymph nodeswellings. For very superficial swellings, an acousticstand off pad was used to improve resolution. Thesonograms were interpreted by the same radiologist.

The findings obtained by Ultrasound werecompared with the histopathological diagnosis.

Analysis of data was done as follows.

a = true positiveb = false positivec = false negatived = true negativeSensitivity = a / a+c X 100Specificity = d / b+d X 100Positive predictive value = a / a+b X 100Negative predictive value = d / c+d X 100Efficiency of study = a+d / total cases X 100

A positive Ultrasound-Histopathology correlationis taken as true positive (TP) whereas Ultrasound-Histopathology disagreement is either false positive(FP) ie histology negative & Sonography positiveor false negative (FN) ie Histology positive &Sonography negative. Cases where histopathologywas negative is taken as true negative.Histopathology is taken to be the gold standard ofcomparison.

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Table 3: Validity Of USS

Positive USS Present in Absent in PPV

Histology Histology 100 %

TP = 6 FP = 0

Negative USS FN = 4 TN = 46 NPV 92%

Sensitivity Specificity Accuracy

60 % 100% 92.8%

True negative cases are those where bothhistopathology and ultrasound scan show benignlesions. Sensitivity is the positivity of ultrasoundscan when malignancy was present. Specificity isthe fraction of cases with benign histopathologyreport that had benign ultrasound scan report.

Table 4: Diagnostic Indices of Ultrasound

Scan

Index Reactive Sialadenitis

change node

Sensitivity 100 % 87 %

Specificity 98 % 98 %

Positive predictive

value 92 % 93 %

Negative

predictive value 100 % 95 %

Accuracy 100 % 96 %


USS REPORT HISTOPATHOLOGY

Sialectasia Sialadenitis

Necrosis node Sialadenitis

Ameloblastoma Gorlin cyst

Non-specific lymphadenitis (n=3) Metastatic node (n=3)

Sialadenitis Adenoid cystic carcinoma

Table 2: Correlation Between USS & Histopathology

HISTOLOGY FREQUENCY CORRECT INCORRECT

DIAGNOSIS BY DIAGNOSISBY

USS USS

Sialadenitis 15 13 (87%) 2 (13%)

Metastatic node 9 6 (67%) 3 (37%)

Reactive node 12 12 (100%) 0

Abscess/ suppurative

lesion 2 2 (100%) 0

Cysts 6 5 (83%) 1 (17%)

Ameloblastoma 1 1 (100%) 0

Pleomorphic adenoma 3 2 (67%) 2 (33%)

Lipoma 1 1 (100%) 0

Angioneurotic odema 2 2 (100%) 0

Hemangioma 1 1 (100%) 0

Adenoid cystic

carcinoma 1 0 1(100%)

Thyroid-MNG 1 1 (100%) 0

Thyroid-Colloid 1 1 (100%) 0

TB lymph node 1 0 1 (100%)


Results

The age of the patients selected ranged from 8 yearsto 78 years. 55.3 % (n=31) were males while 44.6%(n=25) were females. Out of the 56 swellings, 40were non-neoplastic in nature. Of the 16 neoplasticswellings, 6 were benign and 10 were malignancies.On histopathological analysis, the majority ofswellings were sialadenitis, (27%) followed byreactive change lymph node (21%) and metastaticlymph node. (16%)

Ultrasound was sensitive in diagnosing sialadenitisin 13 cases out of 15 cases. (Figure 1). One casewas diagnosed as necrotic node by USS. Thehistology of this case showed sialadenitis withareas of necrosis and fibrosis in the gland. The USSreport may be may be due to an error ininterpretation. USS of the 9 cases of metastaticlymph node from squamous cell carcinoma showedpositivity for 6 cases. (Figure 2). The 3 cases thathad an ultrasound features of non-specificlymphadenitis did not show the classic features ofmetastasis lymph node like loss of fatty hilum,round shape and peripheral vascularity.

Table 1 shows the charted view of discrepanciesbetween USS and Histopathology. One case ofGorlin cyst was diagnosed as ameloblastoma inUSS, the error may be due to lack of penetrance ofUltrasound waves in to bone, which is needed todistinguish between an intrabony cyst andneoplasm. The case of adenoid cystic carcinomadiagnosed as sialadenitis by USS may be aninterpretation error.

Table : 1: USS Report and Histopathology

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Discussion

Anil & Rhodri4 advocates the use of a highresolution, low frequency US machine with a linear7-11 MHz probe for head & neck swellings. Theyalso advocate the extended-neck position on amobile table for scanning. Most authors advise theuse of 7- 13MHz probe for head & neck USS5,6,7.Paul6 advocates the use of a continuous sweeptechnique in the head & neck region. In our study,Sonograms were obtained with high resolution realtime scanner with an 8-11MHz linear array scannerhead. A 45 degree reclined position was used.

Sialadenitis

Ultrasound scan in sialadenitis show a heterogenouspattern due to microabcesses. An illdefinedhypoechogenicity is seen in an abcessed gland4. Ourfindings tally with the authors. Ultrasound wassensitive in diagnosing sialadenitis in 13 cases outof 15 cases of sialadenitis, in our study.

Metastatic lymph node

There are many sonographic criteria for detectionof metastatic lymph nodes4. They include increasedsize, a more rounded shape, an absent echogenichilus or a thin hilus with associated eccentriccortical widening, presence of necrosis within thenode, presence of a cluster of nodes, spread. Otherdiagnostic features like sonographic M/Q quotientand contrast enhanced color doppler features havealso been described for metastatic node diagnosis8,9.Reported figures of accuracy in detecting metastaticcervical lymph node was 75% to 82% in clinicallyN0 necks9. In our study, we found that presence ofan echogenic hilus, an oval shape and a centralpattern of blood flow to be the most commonfeatures for benign swellings. USS of the 9 casesof metastatic lymph node from squamous cellcarcinoma showed positivity for 6 cases. The 3cases that had an ultrasound features of non-specific lymphadenitis did not show the classicfeatures of metastasis lymph node like loss of fattyhilum, round shape and peripheral vascularity.

Reactive lymph nodes

Knappa et al5 stated that retropharyngeal nodes andmicrometastases less than 4mm in size are thelimitations of USS in the head & neck. Jorg et al(2000) stated that USS had a sensitivity of 98%and specificity of 100% in diagnosing reactivechange in lymph nodes of head & neck. In ourstudy, the sensitivity of USS for reactive lymphnode was 100%. The specificity was 98%, withpositive and negative predictive values of 92% and100% respectively. The accuracy of USS was 100%in detecting reactive node.

Conclusion

Ultrasound scan was 60% sensitive, 100% specificand 92.8% accurate for diagnosing malignancy inmaxillofacial swellings.. Errors in USS were errorsof interpretation. False positive diagnosis was dueto error of interpretation while false negativediagnosis was due to error of sampling.

Ultrasound scanning is a highly reliable non-invasive technique for rapid investigations of head& neck soft tissue swellings. It may be used as anadjunctive procedure for pre-surgical evaluation ofswellings, especially when the relationship withadjacent anatomy poses a surgical dilemma. Thenecessity of specific morphologic criteria todistinguish benign from malignant swellings, reducesthe specificity of USS when used as a sole method.Ultrasound combined with FNAC is highly accuratedue to the low prevalence of non-diagnosticsampling in such settings.

Figure 1:

Twinkle S Prasad , Minu Sugathan, Anita BalanTrivandrum Dental Journal 2018 Vol 8, Issue - 1

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Figure 2 :

References :

1. Koss LG. Thin needle aspiration biopsy(Editorial). Acta Cytol 24(1):1;1980.

2. Harnsberger HR. Hand book of Head & neckimaging,2nd edition. St Louis: Mosby yearbook;1995

3. Solbiati L, Rizzatto G. Ultrasound ofsuperficial structures. Edinburgh: ChurchhillLivingstone,1995.

4. Anil T Ahuja, Michael Ying. Sonographicevaluation of cervical lymph nodes. AJR

2005;184:1691-1699.

5. Knappe M, Louw, Gregor RT.Ultrasonography guided FNA for theassessment of cervical metastases. ArchOtolaryngol Head Neck Surgery 2000; 126:1091-6.

6. Paul C Hajek, Erich S, Renate T, Dimiter T,Wolfgang K. Lymph nodes of the neck:evaluation with ultrasound. Radiology

1986;158:739-742.7. Bettina S, Jonathan B, Denis K, Jacob S.

Utility and safety of ultrasound guided fineneedle aspiration of salivary gland massesincluding a cytologists review. J Ultrasound

Med 2004;23:777-783.8. Steinkamp HJ, Zwicker C, Langer M, Mathe

M. Reactive enlargement of cervical lymphnodes and cervical lymph node metastases:sonography M/Q quotient and CT. Aktuelle

Radiol 1992 jul;2(4):188-195.9. Sako K, Pradier RN, Marchetta FC, Pickren

JW. Fallibility of palpation in the diagnosisof metastases to cervical nodes. Surg Gynaecol

Obstet. 1964;118:989-990.

Twinkle S Prasad , Minu Sugathan, Anita BalanTrivandrum Dental Journal 2018 Vol 8, Issue - 1

Source of Support : NilConflict of Interest : None Declared

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Shabna Fathima S.1, Jincy Thomas2, Sunila Thomas3, Vivek Velayudhan Nair4

ABSTRACT

A non-tender, non-scrappable white patch was noted on the left lateral margin of the tongue in a 33-year-old male patient. The differential diagnosis considered were leukoplakia, frictional keratosis,candidiasis, lichen planus, verrucous carcinoma and syphilitic leukoplakia. Incisional biopsy revealedmoderate epithelial dysplasia. Leukoplakia is a potentially malignant disorder of oral mucosa. Dentisthave an important role in the early diagnosis when leukoplakia is usually asymptomatic.

Keywords: white patch, tongue lesion, leukoplakia

CASE REPORT

A 33 year old male patient reported to the department of Oral Medicine and Radiology forevaluation of a white lesion of the tongue, which was noticed 3 months back. He was a gym coach andgives a positive history of using anabolic steroids for 3 months. Extraoral examination did not reveal anyabnormalities. There was no evidence of lymphadenopathy. There was no history of previous similarlesions elsewhere or any systemic complaints. Intraoral examination revealed thickened, painless whiteplaque measuring approximately 1x2cm on the left lateral margin of the tongue. The lesion had irregularborders. On palpation, the lesion was non-tender and non-indurated. The lesion could not be wiped off.

White Lesion on Tongue : A Clinico Pathologic

Conference

Address for Correspondence:Dr. Shabna Fathima S.,V.M. Manzil, Kalakulam via.,Azhicode, Thiruvananthapuram, Kerala, India.Phone: (mobile) +91 9995415422e-mail: [email protected]

DIFFERENTIAL DIAGNOSIS

Based on the clinical appearance of thelesion and the patient’s significant history of usingsteroids, leukoplakia was the most favourableclinical diagnosis. Leukoplakia is termed a whitelesion of the oral cavity that cannot be scrappedoff or designated as any other definable white lesion.Typically, oral leukoplakia ranges from simplekeratosis to different severities of epithelialdysplasia to carcinoma in situ. The exact etiologyof leukoplakia is unknown, although a widw rangeof physical and chemical agents, such as alcohol

and cigarettes, betel quid, microbial infection andultraviolet radiation are implicated in theetiopathogenesis of leukoplakia. The clinicalappearance of leukoplakia is essentiallycategorized into 2 forms: homogenous and non-homogenous forms. The homogenous type ofleukoplakia is defined as a white lesion exhibitinga thin uniform surface and smooth texture, whereas the non-homogenous variety is defined as awhite or white and red lesion that exhibits a widerange of surface irregularities, including papillaryor veruccous, fissured, wringles, nodular, andspeckled. The non-homogenous subtype ofleukoplakia, especially that located on the high-risk areas, such as the lateral borders and ventralsurfaces of tongue and floor of mouth, carry anincreased risk of malignant transformation.Leukoplakias of the tongue, lip vermillion, andfloor of the mouth make up more than 90% ofthe cases of dysplasia and/or carcinoma. Between


1) Senior Lecturer, Oral Medicine & Radiology2) Reader of Oral Medicine & Radiology3) Professor of Oral Medicine & Radiology4) Professor & Head, Oral Medicine & Radiology

CASE REPORT

Shabna Fathima S., Jincy Thomas, Sunila Thomas, Vivek Velayudhan Nair

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0.13% and 364% of leukoplakia develop into oralsquamous cell carcinoma over a follow-up periodof 1 to 11 years. This wide variation in the rate ofmalignant transformation is possibly because ofdisparity in oral and dietary habits, presence of alesion in a non-smoker, occurrence in females,erythematous component, thick lesions, presenceof pain, presence of dysplasia, and persistence overlong periods of time. A biopsy is compulsory formaking a definitive diagnosis and deciding thepreferred treatment for leukoplakic lesions. Thetissue samples should be taken from the clinicallymost severe area.1

Another prime consideration was trauma-induced frictional keratosis. Frictional keratosis ofthe oral cavity id categorized as a normalhyperplastic response induces because of chronicrubbing or friction. It is most commonly seen inareas that are highly susceptible to trauma, such asthe lips the lateral borders of the tongue, buccalmucosa and the edentulous alveolar ridges. Itappears as a white lesion with a roughenedkeratotic surface resembling a callus of the skin.The lesions of frictional keratosis usuallycompletely resolve after the source of trauma isremoved. Our patient denied any trauma to theregion before the appearance of the lesion. Theteeth in the area did not display any sharp orirregular surface and edges. Although the clinicalpresentation of the lesion favoured frictionalkeratosis, the possibility of trauma inducing suchan intense lesion on the dorsum of the tongueseemed highly unlikely.1,2

We also considered candidiasis asone of the differentials, although the clinicalcharacteristics and the patient’s medical history didnot support this. The lesion did not wipe off.thepatient did not present with any predisposing factorsfor candidiasis, such as acquired immunodeficiencysyndrome or diabetes mellitus, usage of broadspectrum antibiotics, or nutrition deficiencies.Therefore, we limited our choice to only thehyperplastic variant of candidiasis. Hyperplasticcandidiasis is the least common form of candidiasis

and is considered to be a controversial diagnosis. Itis speculated to be a candidial infection of anunderlying leukoplakia. The most common locationfor this form of candidiasis is anterior buccalmucosa, at the commissures, followed by the lateralborder of the tongue, although it can be found onany mucosal surface. Clinically, the lesion appearsas well-defined, occasionally raised with smalltranslucent , white areas of large, dense, opaqueplaques. The lesions may also be nodular,homogenous , or speckled. The white plaques ofhyperplastic candidiasis are hard and rough topalpation. Most importantly, the lesions do not ruboff. Hyperplastic candidiasis exhibiting a speckledclinical appearance usually has an increasedfrequency of epithelial dysplasia microscopically.These lesions are associated with malignanttransformation in up to 15% of reports. A biopsyis mandated when the lesion fails to resolve withantifungal medication.2

Another consideration was plaque-typelichen planus (LP), a subtype of reticular LP whichexhibits a leukoplakia-like presentation, displayinga smooth or flat surface with irregular or elevatedareas. This type is mostly seen on the dorsum ofthe tongue and the buccal mucosa. It typicallymanifests as smooth white plaques with atrophyof the papillae. The characteristic white striationsare usually not seen in the plaque-type LP. Amongthe various types of LP the plaque variant was ourmost favourable choice based on the clinicalappearance and the location of the lesion, althoughthe absence of any such lesions elsewhere in thebody or in the oral cavity made this diagnosis lesslikely.2

The thickness and the slightly corrugatedsurface also prompted a likelihood of verrucouscarcinoma (VC) as one of the differentials, althoughthe lack of history of smokeless tobacco usagedeemed it less favourable. VC is considered to be awell-differentiated variant of squamous cellcarcinoma. VC is mainly seen in older men. It maydevelop in association with long-term use of drysnuff, and corresponds to the site of tobacco

Trivandrum Dental Journal 2018 Vol 8, Issue - 1 Shabna Fathima S., Jincy Thomas, Sunila Thomas, Vivek Velayudhan Nair

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placement. Te most common intraoral sites are themandibular vestibule, gingiva, buccal mucosa,tongue, and hard palate. The clinical appearanceof VC is characterized by thick, well-demarcatedplaque with shaggy papillary surface projections.The color of the lesion my vary from white toerythematous to pink depending on the amount ofkeatinization. VC has the tendency to invade theadjacent structures, including the bone and cartilageif left untreated.2

We also considered the diagnosis of syphiliticleukoplakia an oral manifestation of syphilis. It iswell known that syphilis may present with a varietyof systemic manifestations, supporting itsdesignation as the ‘great imitator’. Syphiliticleukoplakia is an extremely rare manifestation oftertiary syphilis presenting as diffuse atrophy ofdorsal tongue papillae accompanied byhyperkeratosis. Here is a fourfold increased risk ofdevelopment of squamous cell carcinoma in thesepatients, although many authors dispute this. Thispossibility was not favoured, however because thepatient denied history of syphilis.2

Although white sponge nevus should beconsidered, the relatively short time course of thelesion and the lack of family history argue againstit.

MANAGEMENT AND DIAGNOSIS

An incisional biopsy specimen taken fromthe dorsum of the tongue. Microscopic examinationof the section revealed parakeratinized stratifiedsquamous epithelium with associated moderatelycollagenous connective tissue. Epithelium showsproliferating and confluent rete ridges in both endsand basilar hyperplasia. Mild chronic inflammatorycell infiltrate is present in the subepithelialconnective tissue. A diagnosis of leukoplakia wasgiven.

The patient was prescribed antifungal agentfor 2 weeks. On the follow up visit there wasreduction in the intensity of the lesion. He was thenprescribed topical application of vitamin A andantioxidants. The patient is kept under follow up.

DISCUSSION

Oral leukoplakia (OL) is a potentiallymalignant disorder of oral mucosa. WHO in 1978as a white patch or plaque which cannot otherwisebe characterized clinically or pathologically as anyother disease. In 2012 van der Waal proposed anew definition which includes the histologicalconfirmation “A predominantly white lesion orplaque of questionable behavior having excluded,clinically and histopathologically, any otherdefinable white disease or disorder”. 3

The prevalence rate of oral leukoplakiavaried between 1.7 to 2.7% in general population.


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OL is often found among men, and its prevalenceincreases with age advancement. It has beenestimated that it mainly affects men over 40 years.4

The etiology of OL is consideredmultifactorial, but smoking is the frequentlyinvolved factor. It is much more common amongsmokers than among non-smokers. Alcohol isthought to be an independent risk factor butdefinitive data are still lacking. There are conflictingresults of studies related to the possible role ofhuman papillomavirus infection. As OL can mimica large variety of lesions, in case a possible causalfactor is suspected such as dental restoration,mechanical irritation. In the later case a subsequentevaluation in 4 weeks is needed.3

OL is classified in two main types:homogeneous type which appears as a flat whitelesion and non-.homogeneous type which includesspeckled, nodular and verrucous leukoplakia. Thehomogeneous leukoplakia is a uniform, thin whitearea altering or not with normal mucosa. Thespeckled type is a white and red lesion, with apredominantly white surface. Verrucous leukoplakiahas an elevated, proliferative or corrugated surface.The nodular type has small polypoid outgrowths,rounded predominantly white excrescences.1

Proliferative verrrucous leukoplakia is asubtype of verrucous leukoplakia characterized byan aggressive evolution, a multifocal appearance,resistance to treatment, higher degree of recurrenceand a high rate of malignant transformation.5

Histological appearance of oral leukoplakiavaries between no dysplasia and carcinoma.Dysplasia reflects histological changes which arefollowed by the loss of uniformity or of thearchitecture of the epithelial cells.

The risk factors for malignancy of OL suchas vicious habits (smoking, alcohol intake), clinicalform, location of lesions were studied. Amongthem, tobacco cigarette smoking was reported tobe the most important etiological factor for the

development of oral premalignant lesions and totheir progression into oral carcinoma.6

The usual clinical examination of oralmucosa is most frequently visual. It is the standardconventional method for oral cancer screening. Itdepends on the experience and skills of theclinician. But the risk level of the lesion is difficultto measure. There are many variants of adjunctivetechniques for the detection of potentially malignantdisorders, including oral leukoplakia.

The main objective in management is todetect and to prevent malignant transformation. Atthe first, the ceasing of the risk activities such assmoking is recommended. The degree of dysplasiawill guide the choice of the treatment. Oralleukoplakia presenting low malignant risk (nodysplasia or simple displasia) may be eithercompletely removed or not, and the decision shouldconsider other factors such as location, size and, inthe case of smokers, the patient’s engagement insmoking cessation. In the presence of moderate orsevere epithelial dysplasia, surgical treatment isrecommended. The surgical treatment can useconventional surgery or laser ablation,electrocauterization, or cryosurgery. Recurrence ofOL after surgical treatment has been reported inmore than 10% of cases.3

CONCLUSION

The role of the dentist and general practitioner isimportant in the early diagnosis when leukoplakiais usually asymptomatic and it is simple to removepossible factors involved in its etiology -smoking,thus reducing the rate of malignant transformation.

REFERENCES

1. Regezi J.A., Sciubba J.J.,Jordan RCK. Clinicalpathologic correlations. 5th ed. W.B. Saunders;2008

2. Neville B.W., Damm D.D., Allen C.M., BouquotJ.E. Oral and maxillafacial pathology. 3rd ed. W.B.Saunders; 2009.


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3. Brouns E, Baart JA, Bloemena E, et al. Therelevance of uniform reporting in oralleukoplakia: Definition, certainty factor andstaging based on experience with 275patients. Med Oral Patol Oral CirBucal. 2012:18756–18756.

4. Petti S. Pooled estimate of world leukoplakiaprevalence: a systematic review. OralOncol. 2003;39:770–780.

5. Van der Waal I, Reichart PA. Oral proliferativeverrucous leukoplakia revisited. OralOncol. 2008;44:719–21.

6. Pentenero M, Pentenero M, Giaretti W, et al.Evidence for a possible anatomical subsite–mediated effect of tobacco in oral potentiallymalignant disorders and carcinoma. J Oral PatholMed. 2011;40:214–217.



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Trivandrum Dental Journal 2018 Vol 8, Issue - 1 Roopan Prakash, Arun Mohan, Tharun Varghese Jacob, Manoj S Nair, Arun G Pillai

Introduction

The field of pathology is presently undergoingsignificant changes, in large part due to advancesin molecular analysis of tissue samples. Thecompletion of the human genome sequencerecently, has allowed the researchers to extend theirstudies, seeking genetic factors that are involvedin complex multifactorial disorders. These advanceshave permitted researchers to have insights intomany developmental, infectious, inflammatory,metabolic and neoplastic disorders. Moreover,molecular analysis also led to improvements in theaccuracy of disease diagnosis and classification [1].

Oxford Dictionary has defined microarray as a setof DNA segments of known sequence representingthe complete set of genes of an organism, arranged

REVIEW

Microarray Technology: Review,

Applications And Future ProspectsRoopan Prakash1, Arun Mohan2, Tharun Varghese Jacob3, Manoj S Nair4, Arun G Pillai5

1) Senior Lecturer, Department of Oral Pathology, Sri Sankara Dental College, Trivandrum2) Senior Lecturer, Department of Oral Pathology, Royal Dental College, Palakkad3) Reader, Department of Oral Pathology, Sri Sankara Dental College, Trivandrum4) Professor and HOD, Department of Oral Pathology, Sri Sankara Dental College,Trivandrum5) Senior Lecturer, Department of Oral Pathology, Sri Sankara Dental College, Trivandrum

Address for Correspondence:Roopan PrakashSenior Lecturer, Department of Oral Pathology,Sri Sankara Dental College, TrivandrumEmail: [email protected]: 9071034187

in a grid pattern for use in genetic testing. It is atechnique that allows simultaneous analysis ofthousands of samples on solid substrates [2]. Thusmicroarray technology helps us in getting fasterresults in tedious experimental procedures. Thegeneral uses of microarray technology includes:(i) Genetic mapping and discovering geneexpression profiles in various disorders, (ii) Generegulation studies, (iii) Diagnosis by identificationof patterns of gene expression that define diseasestates and that may represent prognostic indicatorsand (iv) Drug discovery and toxicology [3].

In this review we broadly describe the various types,techniques, applications and advancements inmicroarray technique.

Types of Microarrays

A. Nucleic acid microarrays

Nucleic acid microarrays, or genome chips, use theprinciple of specific nucleic acid base pairing. Theyare generated by immobilizing specific nucleotideprobes on a supporting matrix, which subsequentlybinds to their complementary targets [4]. Glassmicroscope slide, nylon, silicon and nitrocellulosemembranes are the supporting matrices usually used[7]. The nucleic acid probes usually used are cDNA,DNA and oligonucleotides [4].

Abstract

The gold standard for diagnosis of oral disorders is the histopathological analysis of tissues. This diagnosticmethod remains the standard by which all other diagnostic tests are measured. However, the practice ofpathologists depending solely on histopathological diagnosis is being replaced by more specific molecularand immunological diagnostic methods. The identification of new molecular markers for diseases is atedious task. Thus, microarray technology, which allows simultaneous analysis of thousands of sampleson solid substrates, will play a very important role in future research. In this article we review the varioustypes, techniques, applications and advancements in microarray technique.

Keywords: Molecular markers, Microarray technology

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The principle of DNA microarray technology isbased on the fact that complementary sequencesof DNA can be used to hybridise immobilised DNAmolecules. This involves five major multi-stagesteps:

i) Manufacturing of microarrays: This step involvesthe availability of a chip or a glass slide with itsspecial surface chemistry, the robotics used forproducing microarrays by spotting the DNA(targets) onto the chip or for their in situ synthesis.

ii) Sample preparation: This step involves mRNA orDNA isolation followed by fluorescent labelling ofcDNA probes and hybridisation of the sample tothe immobilised target DNA. Initially, total RNAis isolated, which contains mRNA that ideallyrepresents a quantitative copy of genes expressedat the time of sample collection. The quality ofthe RNA sample isolated is important as theoutcome of any microarray experiment depends onit. Then, using a reverse-transcriptase enzyme,sample mRNA extracted from the sample and thereference sample are converted into theircorresponding complementary DNA (cDNA).Next, each cDNA are labelled with a differentlabelling molecule, mostly a fluorescent cyanine dye.

iii) Array hybridization: This step involveshybridisation of the sample to the immobilisedtarget DNA. Hybridisation is the process of joiningtwo complementary strands of DNA to form adouble-stranded molecule. Here, the labelledcDNA (Sample and Reference) are mixed together,and then purified using filter spin columns to removecontaminants such as primers, carbohydrates,lipids, cellular proteins and unincorporatednucleotides. The mixed labelled cDNA is thencompetitively hybridised against denatured PCRproduct or cDNA molecules immobilized on a glassslide. Molecules in the labelled cDNA should bindspecifically to its complementary target sequenceon the array.

iv) Washing: Any labelled cDNA that did nothybridise on the array, is then removed by washing.Cross hybridization is prevented by either

increasing the temperature or lowering the ionicstrength of the buffers [12].

v) Image acquisition and data analysis: Finally, this stepinvolves microarray scanning, and the imageanalysis using sophisticated software programs thatallow us to quantify and interpret the data. Theslide is first dried and placed into a laser scanner todetermine how much labelled cDNA is bound toeach target spot. Laser excitation of the labelscauses a spectral emission. This characteristicspectrum is analyzed using a confocal lasermicroscope. Usually green spots ore used torepresent the genes that are unregulated, comparedto the control sample, yellow to represent the genesof equal abundance in both experimental andcontrol samples and red to represent the genes thatare down-regulated in the experimental sample[7].

Applications of Nucleic Acid Microarray

Technology

Depending on the samples arrayed and markersused, the microarray technology has a very widerange of applications. Since the elaborate detailsof each one is beyond the scope of this review, themain applications can be summarized into twodistinctive applications:

i) Gene expression profiling to measure the expression of

genes between different cell populations.

ii) Comparative genomics to analyse genomic alterations

such as sequence and single nucleotide polymorphisms

[3,5,8].

B. Tissue Microarrays

The basic idea of multi tissue blocks, was firstdescribed in 1986 by Battifora as a ‘sausage’method for immunohistochemical control andstandardization between laboratories. The tissuemicroarray (TMA) technique was described in itscurrent shape by Kononen et al. as late as 1998.Since 1998, TMA has become well established asa method for ‘high-throughput’ of tissue samplesfor immunohistochemistry (IHC) and in situtechniques [9].

Roopan Prakash, Arun Mohan, Tharun Varghese Jacob, Manoj S Nair, Arun G Pillai

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The TMA technology is an economical, time-efficient and statistically powerful method that willgreatly facilitate translational research. With themicroarray technique, up to 1000 minute tissuesamples are arrayed and analyzed simultaneously.As these datasets are typically present in the formof formalin fixed paraffin-embedded tissue blocks,immunohistochemical (IHC) methods are ideal forvalidation. However, performing whole-sectionIHC on hundreds of blocks requires a large bulkreagents and a lot of time. In addition, an averageblock will yield less than 300 slides of 5ìm each.The tissue microarray (TMA) technique solvessome of these problems [10].

The main advantage of TMA technology is that severalhundred representative cores from several hundredpatients can be included on a single glass slide forassay. Thus, significantly more tissue can beconserved than if the blocks were to be sectionedserially.

The major disadvantage of TMA’s is that each core(or set of cores) represents a fraction of the lesion.However, multiple studies in different organsystems have now demonstrated that consistentand comparable results can be obtained using TMAcores as with whole sections [12].

Applications of Tissue Microarray Technology

The most obvious advantage of TMA’s lies in thelarge number of cases that can be processed cheaplyand quickly. A typical TMA block with 240 (80cases with three cores from each case) 0.6mm corestakes 6-8 hours to construct, added to the time forcutting and staining a single section. In contrast, ithas been estimated that an experienced laboratorytechnician will require 24 hours to cut and stain 80cases for IHC [9].

Although the TMA technique was initiallydescribed for characterization of biomarkers incancer research as the conventional methods werefar too elaborate, the utilization of this techniqueis promptly expanding. Simultaneous assessment ofmolecular markers of clinical relevance in hundredsof tissue specimens has significantly made manyadvances in cancer research. Theoretically, anythingthat one can do with regular tissue section could

be extrapolated using TMA. The high-throughputapproach for analysis of intact tissues allowsvalidation of relative frequencies of moleculartargets by IHC, FISH, mRNA, and ISH [10].

TMA blocks can be stored for future studies. If anew marker looks promising, a single section froma TMA could test it on a large panel of tumours. Awhole project could be carried. TMA’s are extremelywell suited for large-scale IHC studies. Stainingvariability decreases because all cases in a TMAblock are processed on a single glass slide [9].

To maximize the success study of various studies,proper consideration must be given to the arraysource. Some researchers construct their ownslides, which require a high level of technicalexpertise and resources. TMA’s are most commonlyused for cancer studies and for basic research. Amajor concern in using TMA for cancer research istumour heterogenecity. If only a small part of thetissue is analyzed, some alterations may goundetected. However this is of minor significanceif the research is aimed at studying expressionprofiles of tumour populations rather thanindividual cases [9]. As molecular research intendedat identifying specific diagnostic markers areincreasing and focus of rational drug design anddevelopment come to the fore, TMA’s may evolveinto a standard investigational tool [10].

References

1. Richard CK, Troy E, Joseph A: Advanceddiagnostic methods in Oral and MaxillofacialPathology. Part I: Molecular methods. Oral SurgOral Med Oral Pathol Oral Radio Endod 2001;92:650-69.

2. Gupta SJ, Bains VK, Jingran R, Madan R, GuptaV, Rizvi I. Microarray: An emerging diagnostictool in Dentistry. Asian Journal of Oral Healthand Allied sciences 2012;2(2):78-83.

3. Majtan T, Bukovska G, Timko J. DNAmicroarray-Techniques and applications inmicrobial systems. Folia Microbiol2004;49(6):635-664.


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4. Sheils O, Finn S, O‘Leary J. Nucleic acidmicroarrays: an overview. Current DiagnosticPathology 2003; 9: 155—158

5. Microarrays: Chipping away at the mysteries ofscience and medicine. Microarray factsheet2007. http:// www.ncbi.nim.gov/primer/microarrays/html.

6. Kuribayashi Y, Morita K, TomiokaH,Uekusa M,LitoD,Omera K. Gene expression analysis byoligonucleotide microarray in oral leukoplakia.J Oral Pathol Med 2009;38:356-361.

7. Ferrari MDL, Resende MR, Sakai K,MuraosaY,LyraL,Gonio T, Mikami Y,TominangaK,Kamei K, Schreiber AZ,TrabazoP,Moretti ML. Visual analysis of DNAmicroarray data for accurate molecularidentification of Non-albicans candida isolatesfrom patients with Candidemia episodes. J ClinMicrobiol 2013;51(11):3826.

8. Naidu CK, Suneetha Y. Current knowledge onMicroarray technology. An overview. Trop JPharm Res 2012;11(1):153-164.

9. Gulmann C, O‘Grady A: Tissue microarrays: anoverview. Current Diagnostic Pathology (2003)9, 149—154.

10. Radhakrishnan R, Solomon M, SatyamoorthyK, Matin LE, Lingen MW. Tissue microarray –ahigh throughput molecular analysis in head andneck cancer. J Oral Pathol Med 2008;37:167-176.

11. Rumeet K, Simranjot K D, Tarandeep K P, AdeshS M, Japneet K ,Borglin S, Joyner D, DeangelisKM, Khudyakov J, Dhaeseleur PD, JoachimiakMP, Hazen T. High throughput molecularprofiling of tumour specimens- Tissuemicroarray: a brief review. Journal of AdvancedMedical and Dental Sciences Research2015;3(1):116-120.

12.GoldstineJ, DavidB, BeizaiP, MiyataH, VintersHV. Tissue Microarrays in the Study of Non-Neoplastic Disease of the Nervous System.Journal of Neuropathology and ExperimentalNeurology 2002;61(8):653-662.



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1. Image acquisition

A good quality photographic image is theprerequisite for the computation procedure. Theindividuals are asked to protrude the tongueoutwards and downwards keeping it in the mostrelaxed position without extra effort. Images of

Trivandrum Dental Journal 2018 Vol 8, Issue - 1 Shali S. Nair, T.T Sivakumar, Anna P. Joseph, Varun B. R, Vinod Mony

Tongue print: an undeniable proof in biometricauthentication – A brief review1 Shali S. Nair, 2T.T Sivakumar, 3Anna P. Joseph, 4Varun B. R, 5Vinod Mony

Abstract

Biometrics based authentication is emerging as the most reliable solution for establishing the identity ofindividuals in a variety of applications. Although many conventional systems are available for biometricidentification each one has its own drawbacks. Tongue print collected from the dorsum of the tonguecarries a great deal of information along with its visual difference in shape, texture and pattern. In thispaper, we are discussing on the various aspects of tongue prints and its recognition as a biometric tool.

Key words: Tongue print, biometric, authentication, digital.

Introduction

Biometric system recognizes persons based on theirphysiological (e.g., finger print, iris) and / orbehavioural (e.g., signature) characteristics or traits.This technology finds various applications forhuman authentication in areas including securecontrol access and forensics. The dorsum of thetongue carries a great deal of information alongwith its visual differences in shape, texture andpattern, which is referred to as the ‘tongue print’.Current modes of biometric systems include fingerprint, palm print, iris scan, face recognition, voicerecognition and signature verification. Tongueprints have been found to be unique for eachindividual and thereby can be a remarkable toolfor biometric authentication.1

Categorization of tongue prints

Classification of tongue features based oncategorization of tongue parameters was put forthby Stefanescu et al in 2014. According to himtongue texture consists of physiological, scrotal andgeographic with tongue shape as ovoid, ellipsoid,

1) Post Graduate Student,2) Professor& HOD,3) Professor4) Assosiate Professor,5) ReaderDepartment of Oral Pathology& Microbiology, PMS Collegeof Dental Science and Research, Vattappara, Trivandrum.

Address for Correspondence:

Shali S. Nair,E- mail: [email protected]

Digital conversion of tongue print images

Computerised tongue image classificationcomprises of two important steps which are tongueimage acquisition and tongue diagnostic software.The software part consists of both image processingpart and database system for archiving andmanaging acquired tongue images. The digitalconversion of tongue print images requires thefollowing steps:

rectangular, pentagonal, trapezoid to asymmetrical.The longitudinal groove include perceptible/imperceptible, rectilinear/twisty, superficial/deepwith sharp/septate lingual apex.2,3 Tongue prints canalso be classified based on five visual parameterssuch as pattern, margin, shape, fissure, and texture.4

(Refer Table 1).

Table-1: Steps for digital conversion of tongue print

REVIEW

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dorsal tongue are captured under the standardizedlighting conditions using a Hi-tech digital SLRcamera with fixed head position and tongueprotrusion while maintaining the distance ofsubject to camera.4 The environment are also takeninto consideration and flash is provided if thelighting of the place is not enough for the colouraccuracy of the tongue image.

2. Pre-processing

The original tongue images are subjected to imagepre-processing before performing featureextraction. Tongue localisation and normalisationare the two important software procedures in pre-processing. This is done by image stretching andextraction of region of interest from original tongueimages. ROI’s (Region of interest) tongue blocksare selected on the central part of original tongueimages manually. The size of whole ROI is preferredto have 128 x 128 pixels and the sub-block having64 x 64 pixels. The image processing part has tongueboundary detection and tongue colour/shape/texture recognition algorithm.5

3. Tongue segmentation

Tongue segmentation is one of the most essentialsteps in automated tongue diagnosis. It is themethod of cropping used to detect the boundaryof tongue body. Previous works on tonguesegmentation used regular gradient operator todetect the boundary of tongue body and then activecontour model is utilized to crop the tongue area.More recently automated tongue segmentation hasbeen done by combining polar edge detector, edge

Steps for digital conversion of tongue print images filtering, edge binarization and active contourmodel. The active contour model (dynamic contourmodel) is a mechanical visual approach to selectthe edge of an item. Active contour is a techniqueused for extracting salient features from an image.6

4. Feature extraction

Shape parameter is calculated by using controlpoints which gives the prominent outlines of shapefeature of tongue. Polar edge detection is used toextract tongue boundary and tongue edge detectionalgorithm for tongue area separation. Edge lineinterpolation is recommended for user interfacesystem for archiving and managing acquired tongueimages.7

Colour information is of great importance for thetongue inspection by computer-aided tonguediagnosis system. In the tongue image, the coloursof the tongue body are classified as light pink, rosepink, red and purple. RGB colour histogram is usedto analyze the different colours of tongue.7

However, the RGB signals generated by differentimaging devices varies greatly due to the usage ofdifferent kinds of digital cameras and dissimilarlighting conditions.

Tongue print textures for personal authenticationhave been done using Wavelet approach and in thisapproach statistical measures are applied to theprocessed images to extract features. Texture oftongue features have also been extracted on basisof Steerable filters and Weber Law Descriptor.Steerable filters have been used to extract regionof interest from the original tongue images, whereas Weber Law Descriptor are used for local featureextraction.5, 8

5. Algorithm Classifier

The statistics which used to describe the processedimages for pattern recognition are fed to the k-NNclassifier (k-nearest neighbour algorithm). It is anonparametric method which assigns query data tothe class that majority of its k-NN belong to andthe performance of k-NN depends on the numberof the nearest neighbour k. The statistics used todescribe the processed image are the mean,standard deviation, smoothness, third moment,uniformity and entropy. The objective of k-NNclassifier is to find the value of k that maximizes

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the classification accuracy and these classifiers havethe ability to explain the classification results.8

6. Soft ware analysis for database matching

Matching feature points between images is one ofthe fundamental issues in computer vision tasks.The tongue images that form training and testingdatabases are randomly selected. Finally, thecorrection recognition is computed for eachexperiment. The Matlab software is used to performwavelet analysis (extract texture features fromtongue images) and to train and test the k-NNclassifier. So the classifier have been trained andtested with k varying from one to five so that thebest recognition rates can be obtained.8 To maketongue recognition more secure there is a need fortongue biometric template with three views left andright lateral view and profile view. This is done sincetongue is a non-rigid organ and due to the difficultyfor a person to keep it straight. Matching the tongueprints are applied by using algorithms and is doneby calculating Euclidian distance that is betweenedge ridge end and all other ridge ends. It is alsosimilarly done between all bifurcations to achievehigh accuracy after taking the average for both inputimages.9

Conclusion

An ideal biometric system depends on parameterssuch as system reliability, cost effectiveness,flexibility, and necessity of physical contact withthe scanning device. Tongue recognition ispredicted to support the facet of identification andnon- repudiation of information. The humantongue presents both geometric outline andphysiologic texture information which arepotentially useful in identity verificationapplications.10, 11

A biometric system is essentially a patternrecognition system which recognizes a user bydetermining the authenticity of a specificanatomical characteristic possessed by the user. Thecomplexity of the tongue prints due to thecombination of multiple recognizable parametersmakes it an ideal tool for biometric authentication.


REFERENCES

[1] Zhang D, Liu Z, Yan J, Shi P. Tongue-Print:A novel biometrics pattern. Adv Biomet.2007; 1174-1183.

[2] Stefanescu CL, Popa MF, Candea LS.Preliminary study on the tongue-basedforensic identification. Rom J Leg Med. 2014;22:263-6.

[3] Radhika T, Jeddy N, Nithya S. Tongue prints:A novel biometric and potential forensic tool.J Forensic Dent Sci. 2016; 8:11-9.

[4] Angelin D, Nair BJ, Sivakumar TT et.alTongue print as a tool for humanidentification? : A pilot study. Trivan DentJ. 2013; 4:58-62.

[5] Choras R S. Biometric identification throughtongue texture measurements. Int J Compt.2016; 1: 73-77.

[6] Zuo W, Wang K, Zhang D, Zhang H.Combination of polar edge detection andactive contour model for automated tonguesegmentation. IEEE Xplore.2004 ;1-4.

[7] Jang JH, Kim JE, Park KM, Park SO, ChangYS, Kim BY. Development of the digitaltongue inspection system with image analysis.IEEE. 2002; 2: 1033-1034.

[8] Lahmiri S. Recognition of tongueprinttextures for personal authentication: awavelet approach. J Adv Inf Tech. 2012 ;3:168-175.

[9] Diwakar M, Maharshi M. An extraction andrecognition of tongue-print images forbiometrics authentication system. Int JComput Appl. 2013; 61:36-42.

[10] Bade A, Chavan K, Admane P, KomatwarR. Tongue recognition system forauthentication. Int J Res Appl Sci EngTechnol. 2015; 3:76-80.

[11] Zhang DD,editor.Biometric Solutions: ForAuthentication in an E-world. Vol.697.Germany:Springer Science and BusinessMedia; 2012.p.1-21.

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Introduction

With the introduction of digital technologiesbeginning with shade selection systems, intra oralscanners and CAD/ CAM SOFTWARE, skillfulhuman manufacturing effort was considerablydiminished by concising the entire tedious processof shade selection, impression making, diepreparation,wax pattern fabrication and investing.This was followed by 3D printing technologieswhich further simplified process and now thetechnology have come up till 4D printing.Major challenges encountered during fabrication ofan extra coronal restoration is difficulty ininculcating natural appearance and biomechanicsconcurrently. Multi –layered restorations areaesthetically pleasing compared to monolithicrestorations. This review describes the prospect ofautomated manufacturing of multi material multi-

layered anterior esthetic restorations with help ofdigital technology called 4D printing.[1]

Digitalizing Era

1971 marked the initial attempts for computer-assisted production of dental restorations.Commercialization of portable computers fasteneddevelopment in the area of computer-aided design/computer aided manufacturing (CAD/CAM)systems. [2] History of 3D printing can be traced backin 1984 when the technology for printing physical3D objects was developed by Charles Hull. Henamed it stereolithography and obtained a patentin 1986.

All 3-D printers use 3-D CAD software thatemploys an additive manufacturing of series ofcross-sectional slices on a layer-by-layer basis.The3-D machine uses a computer-controlled ultravioletlaser to harden thin layer of liquid resin in thespecified cross-section pattern and excess is washedoff using chemical bath.[9]

Two main benefits of 3-D printing over other rapidprototyping technologies is cost effectiveness andits ability to seamlessly integrate with computer-assisted design (CAD) software and other digitalfiles like magnetic resonance imaging.[9]

Revisualising Esthetics -

A Glance Into 4D Printing : A Literature Review

Trivandrum Dental Journal 2018 Vol 8, Issue - 1 Anu Mary Joy, Sangeeth K Cherian, Sudeep S

PMS COLLEGE OF DENTAL SCIENCE AND RESEARCH,

Golden Hills,Venkode P.o,VattapparaTrivandrum District, Kerala, India-695028

Address for Correspondence :Anu Mary Joy

[email protected], 8113963871

ABSTRACT

Statement of problem. Success of an esthetically and functionally efficient extra coronal restorationdepends upon the precision in the tooth preparation as well as the manufacturing procedures. Thecompetent and successful practitioner must therefore have a strong background in basic tooth preparationprocedures, be knowledgeable of laboratory procedures and keep abreast of the emerging digitaltechnologies.

Purpose. The purpose of this article is to review latest advances in the field of fixed prosthodonticswith the introduction of 4D printing.This information would enable clinicians to improve quality,accuracyand longevity of prosthesis.

Keywords: multi material, multi-layered,esthetics,automated manufacturing,4D printing

Anu Mary Joy1, Sangeeth K Cherian2, Sudeep S3

1. PG Student2. Professor, Prosthodontics,3. Professor & Head, Prosthodontics

REVIEW

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Manufacturers including Zcorp, Objet Geometries,Dimension, Designcraft, Stratasys and 3D Systemsintroduced 3 D printers in market.Raw materialssuch as plastics,resins,super alloys such as nickel-based chromium and cobalt chromium ,stainlesssteel.,Titanium,polymers and ceramics are beingused.[9]

Material & Methods

1. Capture and Digitize[1]

Analogue numerical capturing

Computed tomography/cone beam computer tomography

Micro computed tomography

Ultrasonic acquisition

Light-optical acquisition

2. Print [1]

Binder jetting : Stereolithography (SLA), Selectivelaser sintering (SLS),Indirect 3D-printing (powderbed printers),LOM-Technologies (laminated objectmanufacturing).

Material jetting : Fused deposition modeling-technologies (FDM),Direct 3D-printing,3D-material-extrusion of pastes, Polyjet-technologies.

Workflow[1]

1. Additive Build Up Of Sliced Data2. Slicing Of Data3. Analysing STL Data4. Surface Quality Optimisation5. Generation OfSTL Data6. Data Aquisition

Only monolithic restorations were manufactureduntil 2014 since the combination of 3D-multipartand multicolour printing in a single manufacturingprocess was not possible using the technology.

A thorough understanding of the histo-anatomicstructures and dynamic light interaction of thenatural dentition such as the tri-dimensional formof the dentine core, defined by the dentino-enameljunction,the sigmoid curve distribution (convexenamel/concave dentine) and outer enamel surfaceenabled the invention of 3D multilayeredmultimaterial printing with help of 4 D printing.

Junctinal interface of enamel and dentin isdue to the difference of birefringence between thetissues.The DEJ is less mineralized than eitherenamel or bulk dentin, conversely being richer thaneither in organic matrix. The microstructure ofenamel is dominated by hydroxyapatite crystal-richenamel rods, cemented together by an organicmatrix protein,where as microstructure of coronaldentin appears to be that of a mineralized collagenfiber bio-composite, the intertubular dentin beingthe matrix and the dentin tubule lumens with theirassociated cuffs of peritubular dentin forming thecylindrical fiber reinforcement.polymer.[5]

4D Printing

Fabrication of an extracoronal restoration is ahighly technique-sensitive procedure that needs aconsiderable amount of experience, several stepsare often necessary to achieve pleasing aestheticoutcomes. Thus Automated Digital Fabrication

of Multi-layered restorations is gaining moreacceptance.

Printing dental restorations by additivemanu-facturing with different materials of differentproperties and colours is now possible in one build-up process called MULTI-MATERIAL-3D-

PRINTING/4D PRINTING.[1]

Various multi-material 3 D-printers currently inmarket are PolyJet-3D-printing (Stratasys), MultiJet-Printing (MJP; 3D Systems) and MultiJet Fusion–3D-printing (Hewlett Packard).WZR-Multimaterial- 3D - printing (WZR ceramic solutions GmbH,Rheinbach) is the only system indirect multi-material-printer available and is patented by WZR.[1]

3d Multi-material-printing of replicas of

Natural Teeth

Replicas of extracted intact natural teeth wereproduced and subsequently evaluated.For theaquisition of datasets, extracted teeth were scannedusing micro-computed tomog-raphy (exaCT SDesktop-CT S60 HRE; Wenzel Volumetrik GmbH,Singen, D) with a voxel-size of 45 ìm. Theaquisition software ‘exaCT Control Analysis’(Wenzel Volumetrik GmbH, Singen, D) was usedto generate STL-data of the enamel (including OES


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and DEJ), as well as data of the dentine coreincluding the root and pulp cavity.[1]

The optimisation of the surface quality used thesoftware Sensable Freeform (3D Systems, RockHill, US). Dependent on the individual situationthe ‘natural blueprint’ might be manually alteredusing existing CAD-software.STL-data wereanalysed with the software Magics RP (Materialise,Leuven, Belgium), to detect and eliminate possibleerrors within the dataset. The positioning of theteeth on the printing platform and the slicing ofdatasets was obtained with the software ObjetStudio (Stratasys, Eden Prairie, MN).[1]

On the basis of the sliced datasets the teeth wereadditively build up using the direct-3D-printing-system ‘Objet260 Dental Selection’ (Stratasys). TheObjet260 Dental Selection is the most current 3Ddental printer with triple-jetting-technology.[1]

Applied Materials

For the root and dentine-core the material ‘ObjetVeroGlaze MED620’ was used in shade A2. Thismaterial exhibits sufficient strength and formstability and a translucency compa-rable to naturaldentine. VeroGlaze is currently approved fortemporary intraoral application of maximum 24hours. Therefore it can be applied for diagnostictry-ins and mock-ups.[1]

The incisal area was printed using the trans-parentand strong material ‘Objet MED610 Biocompatible,Clear’.Both materials were printed simultaneously.For the outer surface,glossy-mode was enabled tocreate automatic surface finish..The object to beprinted has to be positioned in the right directionon the platform because the remaining surfacesfacing the platform (where the support structuretouch platform) stay with a mat finish.[1]

Evaluation Of Printing Results

Evaluation criteria for printed object included the‘aesthetic appearance’ and the ‘surface quality’. Theadditively produced teeth show light dynamiceffects and esthetic appearance that simulatenatural model teeth. They are likely caused by thescattering of the light on the dentine-core, leadingto several specific effects in the incisal area.[1]

Conclusion

There are many advantages for 4 D printinglike predictable esthetical results and opticalbehavior, fast production and reproduciblility,economical and considerably simplifiedmanufacturing effort. Current drawback of additivematerials is that the photopolymers have only beenapproved for intraoral use for only 24 hours. Thematerial has only been tested for irritation.Medicalaccreditation regarding cytotoxity, genotoxity, type4 hypersensitivity has to be obtained yet.Inferiormechanical properties is another majordisadvantage.[1]

With advancement in newertechnologies,these disadvantanges are expected tobe overcome in recent future.

References

1. Schweiger J, Beuer F, Stimmelmayr M,Edelhoff D, Magne P, Güth J. Histo-anatomic3D printing of dental structures. BDJ.2016;221(9):555-560.

2. Azari, A. and Nikzad, S. (2009). Theevolution of rapid prototyping in dentistry:a review. Rapid Prototyping Journal, 15(3),pp.216-225.

3. Magne P. A new approach to the learning ofdental morphology, function and esthetics:the ‘2D 3D 4D’concept. Int J Esthet Dent2015; 10: 32–47

4. Magne P. Rationalisation of estheticrestorative dentistry based on biomimetics.J Esthet Restorative Dent 1999; 11: 5–15

5. Bazos P, Magne P. Bio-Emulation:biomimetically emulationg nature utilising ahistoanatomic approach; visual synthesis. IntJ Esthet Dent 2014; 9: 330–352

6. Bazos P, Magne P. Dent. Bio-Emulation:biomimetically emulating nature utilizing ahisto-anatomic approach; structurealanalysis. Eur J Esthet 2011; 6: 8–19


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7. Schweiger J. Method, device and computerprogramme for producing a dental prosthesis.2011; EP 000: 002, 363: 094 A2.

8. Dawood A, Marti B, Sauret-Jackson V,Darwood A. 3D printing in dentistry. BDJ.2015;219(11):521-529.

9. Berman B. 3-D printing: The new industrialrevolution. Business Horizons.2012;55(2):155-162.

10. Strub J R, Rekow E D, Witkowski S.Computer-aided design and fabrication ofdental restorations: cur-rent systems andfuture posibilities. J Am Dent Assoc2006; 137:

1289–1296.

11. AndonoviÆ V, Vrtanoski G. Growing rapidprototyp-ing as a technology in dentalmedicine. MechEngSci J 2010; 29: 31–39

12. . Liu Q, Leu M C, Schmitt S M. Rapidprototyping in dentistry: technology andapplication. Int J AdvManufTechnol2006; 29:

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13. Bammani S S, Birajdar P R, Metan S S.Application of CAD and SLA Method in


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15. Lin W S, Chou J C, Metz M J, Harris B T,Morton D. Use of intraoral digital scanningfor a CAD/CAM-fabricated milled bar andsuperstructure framework for an implant-supported, removable complete den-talprosthesis. J Prosthet Dent 2015; 113: 509–515.

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2008; 29: 494, 496, 498–505.

Anu Mary Joy, Sangeeth K Cherian, Sudeep S


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Trivandrum Dental Journal 2018 Vol 8, Issue - 1 Sreeja C Babu, Noxy George Manjuran, Sudeep S

Introduction

The favourable long-term clinical survivalrates reported for titanium and its biomedical alloyshave made titanium the “gold standard” materialfor the fabrication of endosseous dental implants.The principal disadvantage of titanium is its darkgreyish colour, which often is visible through theperi-implant mucosa, therefore impairing estheticoutcomes in the presence of a thin mucosal biotype.Unfavourable soft tissue conditions or recession ofthe gingival may lead to compromised esthetics.This is of great concern when the maxillary incisorsare involved. Furthermore, it has been suggestedby various investigators that metals are able toinduce a nonspecific immunomodulation andautoimmunity. Galvanic side effects during contactwith saliva and fluoride are also represented.Although allergic reactions to titanium are very rare,cellular hypersensitivity reactions have beendemonstrated. To overcome these limitations andminimize negative biological reactions, researcheshave been focused on designing alternative

A Quest For Gold Standard In Implants

Department Of ProsthodonticsPMS College of Dental Science & Research,Vattappara, Trivandrum, Kerala

Address for Correspondence :Dr. Sreeja C Babu

Contact no: 9446532852email id: [email protected]

substitutes to titanium6. The novel materials includeZirconia, PEEK, Ti-Ta alloy, Ti-Zr alloy and Ti-Au alloy (a promising material which can beintroduced into implant dentistry)

Ideal Properties7

1.Modulus ofElasticity Comparableto Bone2.Increased Interfacial Shear Strength3.High Compressive Strength and Tensile Strength4.High Yield Strength and Fatigue Strength5.Minimum Of 8% Ductility6.Increased Surface Tension and Surface Energy7.Increased Surface Roughness10.Corrosion Resistance11.Biocompatibilty12.Flexural Strength13.Decreased Bacterial Adhesion14.Osseointegration

Zirconia1

High Strength Zirconia ceramics have becomeattractive as newmaterials for dental implants.Yttriastabilized tetragonal zirconiapolycrystals(Y-TZP) with or without the addition of a smallpercentage of aluminaare used for producing dentalimplants.

Advantages : 1) Esthetic - The fact that ceramicmaterials are white and mimic natural teeth betterthan the grey titanium allows an ‘improved estheticreconstruction for patients. Using white ceramicimplants would preclude the dark shimmer oftitanium when the soft peri implant mucosa is ofthin biotype or recedes over time.

Sreeja C Babu1, Noxy George Manjuran2, Sudeep S3

ABSTRACT

With technological advancement, treatments with dental implants have gained increased acceptance bypatients. Competitive researches are in progress all over the world to reach the goal of ideal implantmaterial that simulates a natural tooth. Here is a review of leading implant materials that are vying toclaim the title of ideal implant material

Key words :dental implants; implant materials; titanium; zirconia; PEEK; tantalum;Roxolid;titanium–zirconium; biocompatible; titanium gold alloys.

1. PG Student2. Reader, Prosthodontics3. Professor & Head, Prosthodontics

REVIEW

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Trivandrum Dental Journal 2018 Vol 8, Issue - 1 Sreeja C Babu, Noxy George Manjuran, Sudeep S

2) Highest uni axial flexural strength amongceramics

3) Highest fracture toughness among ceramics-Osman et al mentioned that at room temperatureand upon heating up to 1170 °C, the structure ismonoclinic. It assumes a tetragonal shape between1170 and 2370°C and a cubic structure at atemperature higher than 2370 °C and up to themelting point. Alloying pure zirconia withstabilizing oxides, such as CaO, MgO, Y2O3 orCeO2, permits the retention of the metastabletetragonal structure at room temperature.Dentalprocedures, like grinding or sandblasting, can triggera tetragonal to monoclinic transformation withinthe surface region . This transformation isaccompanied by a considerable increase in volume(~4.5%) that induces surface compressive stresses,thereby closing the crack tip and enhancingresistance to further propagation. Thischaracteristic, known as transformationtoughening, will increase the fracture strength andfracture toughness of Y-TZP ceramics comparedwith other dental ceramics.

4) Osseointegration comparable to Ti (BIC>60%)Deprich et aldemonstrated that zirconiaimplants with modified surfaces resulted in anosseointegration that was comparable with that oftitanium implants.

5) Significant reduction in bacterial adhesion

6) Periimplant tissue compatibility- Theinflammatory response and bone resorption inducedby ceramic particles are less than those induced bytitanium particles, suggesting the biocompatibility.

Disadvantages: 1) Low temperature degradation-As previously mentioned, a certain degree ofsurface tetragonal-monoclinic transformation canactually improve the mechanical properties of Y-TZP. However, a small range exists betweenimprovement and destruction of mechanicalproperties. The transformation of one grain resultsin a volume increase, thereby stressing theneighbouring grains and generating microcracking,which enables further water penetration, crackpropagation and phase destabilization.

2) High Young’s modulus - It has been proven thata big difference between the elasticity of theimplant material and bone leads to greater stressgeneration due to differential deformation underload. This stiffness mismatch can lead to boneresorption as a result of stress shielding.

PEEK3

Advantages: 1) Elastic modulus and density closeto bone(CFR-PEEK) The reinforcing agents usedmay be carbon fibers, beta-tricalcium phosphate,hydroxyapatite or titanium dioxide contained withina PEEK matrix. The filler content makes theimplant isoelastic, i.e. density and elasticity(Young’s modulus) identical to bone. Although purepolyaromatic polymers exhibit elastic modulus thatvaries from 3 to 4 GPa, this value can be changedto attain a modulus close to cortical bone (18 GPa)with the addition of fibers.On the other hand, theYoung’s modulus of titanium and its alloys varyfrom 110 to 150 GPa.

2) BIC greater than Ti

3) Esthetic-Their white colour makes them idealfor use in the esthetic zone

4) Better imaging (MRI &CT)friendly- the presenceof metallic implants i.e. titanium and its alloyssignificantly and negativelyimpacts the quality ofthe resultingimages. On the other hand, theimplantsmade of reinforced PEEK polymerareradiolucent and this feature allowsavoidingscatter in further CTs or MRIs.

5) Do not generate heat during modification- As aresult, the coronal portion of the single pieceimplant can be immediately modified (like crownpreparation for FPD) to meet the prostheticrequirement.

Disadvantages: 1) No inherent Osseo conduction2) CFR PEEK (Carbon fiber reinforced PEEK) notesthetic 3) Lesser strength

Ti-Ta ALLOY (TRABECULAR METAL)5

It is not until the early 1990s that porous tantalumtrabecular metal (PTTM) was introduced.PTTM,known commercially as Trabecular Metal Material(Zimmer, Trabecular Metal Technology, Inc.,

27

Parsippany, NJ) is an open-cell porous biomaterialwith a structure similar to trabecular bone by havingthree-dimensional dodecahedron repeats.

Advantages: 1) Excellent corrosion resistance andbiocompatibility

2) Osteoconductivity, Bone Ingrowth andVascularization - PTTM structure allowsneovascularization and new bone formation directlyinto the implant. This concept is known as “Osseoincorporation”

3) PTTM exhibits an elastic modulus similar tobone and is mechanically superior to other alloysused in dental implants

4) Improved tensile strength than Ti.

Disadvantages: 1) While tantalum itself is similarto titanium in that it is highly biocompatible andcorrosion resistant, the interactions with oral fluid,oral microbes and biofilm of the PTTM portionare not known.

2) Increased bacterial adherence

3) Fracture of implants - Due to implantmanufacturing, the connection between therelatively small titanium core/PTTM in the middle-third portion and the apical titanium portion maybe prone to fracture especially if they are placed inhard bone (type 1) with in appropriate high torque.These implants are however recommended for bonethat are relatively soft (type 3 or 4).

Ti-Zr ALLOY4

Advantages: 1) Biocompatible -a new Titanium–Zirconium alloy (Ti–Zr) has been developed(Roxolid; Institut StraumannmAG, Basel,Switzerland). This material is made of titaniumalloyed with 13–15% of zirconium. This metal alloyis highly biocompatible and allows the same surfacetreatment, sand blasting and acid etching, ascommercially pure titanium grade IV.

2) High strength

3) Corrosion resistance

4) Application in small diameter implants - torestore a reduced mesiodistal space, reducedcrestalwidth (narrow ridge), and reduced amountofinterradicular space

5) Tensile strength of Ti increased withadditionof Zr

6) Increased Elongation and fatigue strength thanpure Ti

7) Excellent osseointegration

8) Reduce the need for bone regeneration - lessresidual bone is needed for implant insertion.

Ti Au ALLOY2

Swanidze et al explained that Ti3Au has significantly

enhanced hardness while preserving itsbiocompatibility. The only other intermetalliccompound with a similar hardness value is Ti

3Ir,

the biocompatible properties of which remainunknown.

Among the Ti–Au binary compounds, Ti3Au is the

only cubic one, which is consistent with highmechanical stability and, therefore, high hardness.

Advantages: 1) Increased density,2) Biocompatibility, 3) Improved corrosionresistance, 4) High mechanical stability

Disadvantages: 1) Increased hardness.

Conclusion :

Comparing newer materials based on their desirableproperties for an implant, TiZr alloy and Zr arefound to have more ideal properties compared toits competitors (basedon available information). Butwe are yet to find the perfect material which willcater to all the biological and mechanicalrequirements of an ideal implant. And for certain,this area has immense scope for further researchand development.

Reference :

1) Osman R, Swain M. A Critical Review ofDental Implant Materials with an Emphasison Titanium versus Zirconia. Materials.2015;8(3):932-958.

2) Svanidze E, Besara T, Ozaydin M, TiwaryC, Wang J, Radhakrishnan S et al. Highhardness in the biocompatible intermetalliccompound -Ti3Au. Science Advances.2016;2(7): e1600319-e1600319.

Sreeja C Babu, Noxy George Manjuran, Sudeep STrivandrum Dental Journal 2018 Vol 8, Issue - 1

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3) Schwitalla A, Müller W. PEEK DentalImplants: A Review of the Literature. Journalof Oral Implantology. 2013;39(6):743-749.

4) Altuna P, Lucas-Taulé E, Gargallo-Albiol J,Figueras-Álvarez O, Hernández-Alfaro F,Nart J. Clinical evidence on titanium–zirconium dental implants: a systematicreview and meta-analysis. InternationalJournal of Oral and Maxillofacial Surgery.2016;45(7):842-850.

5) Bencharit Sompop, ByrdWarren C,AltarawnehSandra,Hosseini Bashir,LeongAustin, Reside Glenn, Morelli Thiago,Offenbacher Steven.Development andApplications of Porous Tantalum Trabecular

Metal Enhanced Titanium DentalImplants.Clin Implant Dent Relat Res. 2014December; 16(6): 817–826.

6) Soni A, Kharbanda P, Kumar A. Search ForA Viable Alternative To Titanium Implants– A Literature Review. Indian Journal ofDental Sciences. 2013;Vol.:5(Issue:3):81-83.

7) 1.Misch CE. Contemporary implantdentistry. 3rd ed. St Louis: Mosby Elsevier;2008.

Sreeja C Babu, Noxy George Manjuran, Sudeep STrivandrum Dental Journal 2018 Vol 8, Issue - 1


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