Comparative Evaluation of PhotoablativeEfficacy of Erbium: Yttrium-Aluminium-Garnet and Diode Laser for theTreatment of GingivalHyperpigmentation. A RandomizedSplit-Mouth Clinical TrialMarco Giannelli,* Lucia Formigli,† and Daniele Bani†

Background: The use of lasers in periodontology is a mat-ter of debate, mainly because of the lack of consensual ther-apeutic protocols. In this randomized, split-mouth trial, theclinical efficacy of two different photoablative dental lasers,erbium:yttrium-aluminum-garnet (Er:YAG) and diode, forthe treatment of gingival hyperpigmentation is compared.

Methods: Twenty-one patients requiring treatment formild-to-severe gingival hyperpigmentation were enrolled.Maxillary or mandibular left or right quadrants were ran-domly subjected to photoablative deepithelialization witheither Er:YAG or diode laser. Masked clinical assessmentsof each laser quadrant were made at admission and days7, 30, and 180 postoperatively by an independent observer.Histologic examination was performed before and soon aftertreatment and 6 months after irradiation. Patients also com-piled a subjective evaluation questionnaire.

Results: Both diode and Er:YAG lasers gave excellent re-sults in gingival hyperpigmentation. However, Er:YAG laserinduced deeper gingival tissue injury than diode laser, asjudged by bleeding at surgery, delayed healing, and histo-pathologic analysis. The use of diode laser showed additionaladvantages compared to Er:YAG in terms of less postopera-tive discomfort and pain.

Conclusions: This study highlights the efficacy of diode la-ser for photoablative deepithelialization of hyperpigmentedgingiva. It is suggested that this laser can represent an effec-tive and safe therapeutic option for gingival photoablation. JPeriodontol 2014;85:554-561.

KEY WORDS

Clinical trial; gingiva; hyperpigmentation; lasers,semiconductor; lasers, solid state; melanins.

Physiologic gingival hyperpigmen-tation (PGH), caused by excessivemelanin deposition by melanocytes

mainly located in the basal and su-prabasal cell layers of the epithelium,1

affects numerous people of differentethnic backgrounds.2 Although PGH isdefinitely benign and does not repre-sent a health concern, complaints ofdark gums are common, particularlyamong individuals with excessive gin-gival display during smiling or talking,which compels them to seek appro-priate cosmetic treatment. Gingivaldepigmentation has been performedusing various methods and techniques,including mechanical abrasion,3 surgi-cal removal,4,5 cryosurgery or electro-surgery,6-8 and chemical etching,9 withdifferent degrees of success. Moreover,some of these techniques are prone toside effects and complications. In recentyears, the use of laser photoablation hasbeen recognized as one of the most ef-fective, pleasant, and reliable techniquesfor this purpose.10 The commonly usedlasers for gingival deepithelializationinclude semiconductor diode,11 erbium:yttrium-aluminium-garnet (Er:YAG),12

neodymium:yttrium-aluminum-garnet

* Odontostomatologic Laser Therapy Center, Florence, Italy.† Department of Experimental and Clinical Medicine, Section of Anatomy and Histology,University of Florence, Florence, Italy.

doi: 10.1902/jop.2013.130219

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(Nd:YAG),13 and CO2.13,14 High-power lasers (CO2,Nd:YAG, diode l 810 to 980) are preferred for soft-tissue surgery because they cause tissue ablation/vaporization, hemostasis, and sterilization.13,14

Instead, Er:YAG laser is commonly used to targethard tissues, such as bone, enamel, cementum,and dentin, and it is recently gaining importanceand interest for gingival deepitelization.15 Recentresearch has centered on pulsed diode laser (l 810)used in photoablative mode in periodontal surgery;this has been primarily used for oral surgery of thetongue and gingiva and in chronic periodontitis toremove the infected epithelium inside and aroundperiodontal pockets.16 Indeed, this laser has someadvantages compared to the others, such as easiergingival reshaping, reduced need for local anes-thesia, excellent hemostasis, minimal thermal injuryof the deeper tissues, and negligible postoperativepain and inflammation.16,17 All these characteristicsmay also be important in the use of diode laser forcosmetic purposes, including the removal of be-nign gingival hyperpigmentation. In keeping withthis hypothesis, there is evidence in the recentliterature of successful depigmentation using di-ode lasers.10,18,19

In the present study, the authors want to furtherexpand the knowledge on the issues discussed aboveby analyzing and comparing the effects of a diodelaser (l 810 nm) and an Er:YAG laser (l 2,940 nm)on gingival depigmentation in terms of the following:1) clinical outcome in the short term and midterm (upto 6 months of follow-up); 2) histologic response ofgingival tissues to laser photoablation; and 3) pa-tients’ discomfort during treatment and preference foreither treatment modality.

MATERIALS AND METHODS

PatientsThe study was designed in compliance with theguidelines of the Declaration of Helsinki, as amendedin Edinburgh 2008, and it was performed in keep-ing with the CONSORT (Consolidated Standards ofReporting Trials) consolidated standards of report-ing trials,20 as summarized in Figure 1. It wasapproved by the Ethical Committee of the Univer-sity of Florence Faculty of Medicine, Florence, Italy.The clinical part of the study was conducted at theOdontostomatologic Laser Therapy Center, Flor-ence, Italy, from March 2012 to February 2013.Twenty-five patients were assessed for eligibility,and 21 of them (10 males and 11 females, aged 18to 40 years; mean age: 26.5 years) enrolled in thestudy and signed a written informed consent. Theypresented hyperpigmentation of the mandibular/maxillary vestibular gingiva at the first clinical ob-servation. Exclusion criteria included the following: 1)

history of systemic diseases; 2) pregnancy andlactation; and 3) heavy smoking habit (‡20 ciga-rettes/day). The inclusion criterion was moderate-to-severe bilateral melanin hyperpigmentation ofthe upper and lower gingivae, as detailed below.Before treatment, small samples of gingival softtissue, 2 · 2 mm, were taken with a biopsy punchfor histopathologic purposes to confirm the clinicaldiagnosis of benign melanin pigmentation. Sevendays later, the patients were recalled and subjectedto laser treatment. Then, a second biopsy wasperformed to exactly determine tissue ablationand thermal damage. When deemed appropriateto reduce hypertrophic gingivae, additional biopsyspecimens were taken from six quadrants in threepatients after 6 months to determine the midtermhistologic response of gingival tissue to laserablation.

Pretreatment and Post-Treatment ClinicalAssessmentThe degree of gingival pigmentation was scoredaccording to the Dummet Oral Pigmentation In-dex:21 0 = pink tissue, no clinical pigmentation; 1 =mild light brown tissue, mild clinical pigmentation;2 = medium brown or mixed brown and pink tissue,moderate clinical pigmentation; 3 = deep brown/blue–black tissue, heavy clinical pigmentation.

The treatment outcome was semiquantitativelyevaluated by the following clinical parameters.Wound healing included the following: 1) completereepithelialization, 2) incomplete reepithelialization,3) ulcer, and 4) tissue defect or necrosis. Assess-ment was performed with the aid of a high-resolutiondigital video microscope‡ at ·50 magnification,which allowed the authors to easily distinguishbetween intact epithelium and fibrin-coated con-nective tissue. Bleeding at surgery included thefollowing: 1) none, 2) slight, 3) moderate, and 4)severe.

Scoring values of the upper and lower quadrantswere merged. The clinical parameters were objec-tively evaluated and scored by the operator (MG) atadmission (day 0) and at days 7, 30, and 180 afterthe treatments.

Patient Randomization and AllocationIn each patient, the upper and lower quadrants wererandomly subjected to one or the other treatment,i.e., diode or Er:YAG laser. Allocation concealmentwas performed by sequentially numbered, opaquesealed envelopes. For each patient, the randomi-zation envelope was opened immediately before thetreatment. Treatment assignment was registered bya non-clinical investigator (LF) and kept concealed

‡ Dino-Lite, Italeco, Turin, Italy.

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to the investigator who performed the statisticalanalyses (DB) until completion of the study. Thenon-clinical investigator was also in charge of ad-ministration to the patients of a satisfaction ques-tionnaire,22 reported in Table 1, for subjectiveevaluation of treatment.

Photoablative Laser TreatmentAll laser procedures were performed by the sameexpert operator (MG). The patients were subjectedto photoablative treatment using the following de-vices: 1) Er:YAG laser,§ l 2,940 nm, pulsed-wave

mode; and 2) diode laser,i

l 810 nm, pulsed-wave mode.The detailed irradiation pa-

rameters, chosen on the basisof those reported previouslyfor the treatment of gingivalepithelial ablation,15-17 aregiven in Table 2.

Laser energy output wasmeasured with a power meterbefore each procedure. To min-imize harmful photothermaleffects, photoablation was per-formed under either air/waterflow (Er:YAG) or airflow (diode)cooling. Photoablation beganat the free gingival margin andproceeded toward the muco-gingival junction, including theinterdental papilla. Irradia-tion was performed in contactmode, with the fiber tip touch-ing the gingival epithelium. Forthe diode laser, the fiber endwas controlled at every irra-diation to check for a carbon-ized tip (hot tip), required togenerate enough thermal en-ergy to cause tissue coagula-tion at the incision line. Excesscarbonized debris was removedwith wet gauze. To preventheat-induced tissue damage,the treatment was performedunder continuous infrared ther-mographic monitoring, settingan 80�C thermal threshold asthe target.16,23,24 The tip wasmoved at a constant speed of2.5 mm/second, evaluatedvisually, to minimize gingivalthermal damage, as demon-strated previously.24 The di-ode laser was also equipped

with a violet-light-emitting diode probe emitting atl 405 nm, which stimulated autofluorescence ofthe photoablated tissue and was clearly visiblewhen wearing yellow–green filtered goggles,23

allowing precise targeting of the photoablativelaser beam; both probes were included in the 4 · 4dental laser.

Local anesthesia was usually unnecessary andwas only performed upon patient demand. Eye

Figure 1.CONSORT flowchart of the clinical trial.

§ OpusDuo ECTM, Lumenis, Milan, Italy.i 4 · 4 Dental Laser, General Project, Montespertoli, Italy.

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protection of the patients and the operator wasensured by wearing safety glasses.

Post-Treatment InstructionsPatients were instructed to discontinue tooth-brushing on the day of laser photoablation to pre-vent mechanical trauma at the treated sites andfacilitate reepithelialization. From day 2, normaltooth hygiene with toothbrush and interproximalinstruments was encouraged. Local use of chlor-exidine digluconate or other local medications wasnot prescribed.

At the 1-day postoperative visit, patients wereasked to grade the treatment modalities in theirorder of preference. One day and 1 week aftersurgery, the patients were asked to respond, basedon visual analog scores, about their perceived de-gree of pain/discomfort.

Biopsy Collections and Morphologic AnalysesAfter admission and 180 days after the lasertreatments, small samples of gingival tissue, �2 · 2mm, including surface epithelium and the un-derlying lamina propria, were taken under localanesthesia using a 2-mm-diameter biopsy punch,paying attention not to expose the periosteum (n =13, seven taken before and six after the treatment).The biopsies collected at the 180-day follow-upwere taken at sites in which there was a therapeuticindication to reduce the periodontal pockets (threepatients). For conventional histology, samples werefixed by immersion in 4% (weight/volume) form-aldehyde in 0.2 M phosphate-buffered saline (pH7.4), dehydrated in graded ethanol, and embeddedin paraffin. Five-micrometer-thick sections werestained with hematoxylin and eosin (H&E) andphotographed under a light microscope.

Table 1.

Satisfaction Questionnaire

Question Scoring

Was the treatment painful? 1, no pain; 2, mild pain; 3, severe pain

Did you experience pain on the day of the treatment? 1, not at all; 2, mild; 3, severe

Did you experience pain during the first week after the treatment? 1, no pain; 2, mild pain; 3, severe pain

Did you notice a cosmetic change 1 week after the treatment? 1, not at all; 2, moderate; 3, marked

Did you notice a cosmetic change 6 months after the treatment? 1, not at all; 2, moderate; 3, marked

Did the treatment meet your expectations? 1, no; 2, yes; 3, over and above

Would you repeat the treatment if necessary? 1, no; 2, yes; 3, over and above

Modified from McGill Pain Questionnaire.22

Table 2.

Laser Irradiation Parameters

Diode Er.YAG

Laser beam characteristicsWavelength 810 nm 2,940 nmIrradiation mode Pulsed wave Pulsed wavePulse energy 69 mJ 100 mJPulse frequency 8,000 Hz 10 HzPulse duration 18 ms 400 msPower (beam, average) 0.6 W 1 WFiber diameter 0.6 mm 0.8 mm

Surface treatment dataTreatment mode Contact tip Contact tipLaser spot at target diameter/area 0.6 mm/0.283 mm2 0.8 mm/0.503 mm2

Fiber movement speed 2.5 mm/s 2.5 mm/sCooling Airflow Air/water flowTotal energy density (fluence) 40 J/cm2 50 J/cm2

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Statistical AnalysesThe patient’s quadrant was assumed as the test unitfor statistical comparison. Values were expressed asmean – SEM. The clinical parameters, which varieddepending on treatment and time, were first ana-lyzed by two-way repeated-measures analysis ofvariance (ANOVA) to assess whether the in-teraction between the two variables was significant.If so, differences between each time point wereassessed by paired t test, followed by Bonferronimultiple comparison test.25 The clinical parameters,which varied depending on treatment alone, namelythose of the satisfaction questionnaire, were ana-lyzed by Student t test for paired values. P <0.05was considered significant.

RESULTS

All the enrolled patients successfully completed thestudy. The results of the semiquantitative analysisof the clinical parameters, e.g., gingival color,wound healing, and bleeding at surgery, performedbefore or soon after the treatments (day 0) andduring the follow-up are reported in Figure 2. BothEr:YAG and diode laser treatments caused a sig-nificant improvement of gingival hyperpigmenta-tion. No recurrence of gingival pigmentation wasfound in any of the patients during the follow-upperiod (Fig. 2A). Er:YAG laser induced deepergingival mucosal injury than diode laser, as judgedby the persistence of scattered deepithelaliizedareas 7 days after treatment that were not found inany of the quadrants treated with diode laser (Fig.2B). Moreover, bleeding at surgery was commonwith Er:YAG laser, although it was never observedin the mucosa treated with diode laser (Figs. 2Cand 3C). Representative clinical images taken be-fore, during, and after the treatments are shown inFigures 3A, 3C, and 3F.

The histopathologic analysis performed on gin-gival biopsies after laser irradiation confirmed andextended the clinical findings. Before laser treatment,the hyperpigmented gingiva showed numerousmelanin deposits in the basal and suprabasal epi-thelial cell layers (Fig. 3B). The diode laser yieldeda complete, uniform removal of the squamous epi-thelium with no appreciable changes of the stromaland microvessel components of the lamina propria(Fig. 3D). Conversely, Er:YAG laser irradiation oftencaused an incomplete ablation of the gingival epi-thelium, with the deeper epithelial ridges remainingin place (Fig. 3E). This required repeated passagesand increased the risk of causing damage to thelamina propria. Moreover, Er:YAG laser irradiationwas often accompanied by microvessel dilation,likely accounting for the marked bleeding at surgery.With the diode laser, the hyperpigmented epithelium

Figure 2.Outcome of the noted clinical parameters during follow-up after thetreatments with either Er:YAG or diode lasers. Differences were assessedby two-way repeated-measures ANOVA and paired t test, followed byBonferroni multiple comparison test. n.s. = not significant.

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appeared to absorb laser energy with higher effi-cacy than the normally pigmented one. In fact,histologic signs of coagulation of the superficialstroma were prominent when the instrument was setin continuous mode (data not shown). For thisreason, it was found that a pulsed-wave irradiationmode was required for optimal photoablative resultswith both of the lasers used. The biopsies taken atthe 180-day follow-up showed a normal gingivalmucosa, with no features of residual hyperpig-mentation (Fig. 3G).

As a final clinical note, the post-treatment coursewas uneventful in all patients, and no complica-tions, such as ulcers, persistent bleeding, or in-fections, were observed throughout the follow-up.Moreover, all patients except one perceived slightor no pain and discomfort during the laser treat-ments and did not require local anesthesia. Sub-jective perception of Er:YAG versus diode lasertreatment evaluated by the patients’ responses toa satisfaction questionnaire showed an overallpreference for the diode laser (Table 3).

DISCUSSION

Despite their indisputable merits in oral surgery,the complexity of medical lasers in terms of dif-ferent wavelengths, energy output modes, and set-ting parameters has produced a multiplicity ofclinical protocols with different outcomes, thushampering comparison of the results and identi-fication of univocal guidelines for their use.26,27 Inthe present study, two different lasers widely usedfor oral surgery, namely Er:YAG and diode laser,were compared with the purpose to define suit-able irradiation protocols for successful removalof hyperpigmented gingival epithelium with minimalundesired mucosal damage. It was found that Er:YAG laser irradiation, although it was able to inducecomplete epithelial photoablation and improve PGHin the long term, required caution to be properlyexecuted. Indeed, it often caused an incompleteablation of the gingival epithelium, with the deeperepithelial ridges remaining in place, thus requiringrepeated passages and increasing the risks ofdamaging the lamina propria. It also causedmarked blood vessel dilatation, accounting for de-layed gingival healing and bleeding at treatment.This was likely attributable to its mode of action,causing a sudden vaporization of water contained inthe targeted tissues. Better results were obtainedusing the diode laser; with the noted irradiationparameters, it yielded a complete removal of thegingival surface epithelium without causing stromaldamage and microvessel dilation. Rather, epithelialphotoablation was accompanied by microvesselnarrowing, possibly related to direct vasomotor

Figure 3.Clinical (A) and histologic (B) features of a typical patient. Thehyperpigmented mucosa is characterized histologically by abundantmelanin granules in the basal/suprabasal epithelial layers. The immediateeffects of laser irradiation on the hyperpigmented mucosa are markedlydifferent (C); the diode laser causes coagulation of the surface epithelium,which appears to be completely removed in the corresponding biopsy (D).Conversely, the Er:YAG laser causes vaporization of the outer mucosa andmarked bleeding, whereas the deeper epithelial ridges are not removedcompletely (E, asterisk). The arrowhead points at the border betweenlaser-ablated and intact mucosa. At the 180-day follow-up after laserirradiation, themucosa shows normal pigmentation at both clinical (F) andhistologic (G) levels. (H&E; Panels B and G: original magnification ·100;Panels D and E: original magnification ·250.) Scale bars = 10 mm.

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effects and/or deactivation of local proinflammatorymediators by the diode laser light.28-30 These fea-tures may likely be attributed to heat-induced co-agulation of the targeted tissues induced by thislaser type. During the follow-up, the quadrantstreated with the Er:YAG laser showed delayedhealing, with a higher bleeding score during thetreatment and a higher injury score at day 7compared to the diode laser. Thus, the diode laseroffers the advantage of a successful and safe ap-plication by being able to prevent bleeding, limitingpostoperative inflammation and pain, and favoringhealing of the gingival mucosa. These findingsconfirm and extend the previous data on the suc-cessful application of laser techniques for thetreatment of gingival hyperpigmentation10,18,19,24

and provide novel evidence that the diode laserfulfills the clinical rationale for minimally invasiveapproaches that reduce intraoperative and post-operative trauma.

Using either Er:YAG or diode laser, it should bepointed out that complete deepithelialization re-quires that the instruments are used in contactmode to get optimal control of the laser beamwithout damaging the neighboring tissues, such asteeth and alveolar bone, and are set in pulsed-wavemode to reduce light absorption by chromophores,such as melanin and oxyhemoglobin, and to limitharmful thermal energy accumulation.

At the 6-month follow-up, both Er:YAG and diodelasers gave satisfactory clinical results, with norecurrence of PGH. It has been suggested that re-currence of gingival hyperpigmentation may initiatefrom epithelial resettlement of residual melanocytesmigrated from the gingival areas that are less easilyaccessible to surgical maneuvers, such as thegingival margins and interdental papilla.14 There-fore, the radical ablation of hypermelanized gingi-vae, as afforded by both laser treatments, can

greatly reduce the probability of PGH relapse in thelong term.

CONCLUSIONS

The results of the present study highlight the effi-cacy of dental lasers, especially the diode laser, forphotoablative deepithelialization of PGH. Comparedto Er:YAG lasers, which are among the most diffuseoral-care laser devices, diode lasers produce similarclinical results in terms of esthetic outcome, plusthe major advantage of minimal injury of the tar-geted gingiva.16,17,24 These features can favor anever-increasing diffusion of diode lasers amongdental practitioners to expand their therapeuticrepertoire.

ACKNOWLEDGMENTS

The authors are grateful to Dr. Alessia Tani, Depart-ment of Experimental and Clinical Medicine, Sectionof Anatomy and Histology, University of Florence,Florence, Italy, for skillful help in the preparation ofhistologic specimens. The authors report no conflictsof interest related to this study.

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Table 3.

Satisfaction Questionnaire Results (mean – SEM)

Question Er:YAG Laser Diode Laser Student t Test

Was the treatment painful? 1.59 – 0.07 1.36 – 0.08 P <0.05

Did you experience pain on the day of the treatment? 1.5 – 0.1 1.07 – 0.05 P <0.01

Did you experience pain during the first week after the treatment? 1.33 – 0.07 1.04 – 0.03 P <0.01

Did you notice a cosmetic change 1 week after the treatment? 3 – 0 3 – 0 NS

Did you notice a cosmetic change 6 months after the treatment? 3 – 0 3 – 0 NS

Did the treatment meet your expectations? 2 – 0 2 – 0 NS

Would you repeat the treatment if necessary? 2 – 0 2 – 0 NS

NS = not significant.

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5. Tamizi M, Taheri M. Treatment of severe physiologicgingival pigmentation with free gingival autograft.Quintessence Int 1996;27:555-558.

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14. Esen E, Haytac MC, Oz IA, Erdo�gan O, Karsli ED.Gingival melanin pigmentation and its treatment withthe CO2 laser. Oral Surg Oral Med Oral Pathol OralRadiol Endod 2004;98:522-527.

15. Azzeh MM. Treatment of gingival hyperpigmentationby erbium-doped:yttrium, aluminum, and garnet laserfor esthetic purposes. J Periodontol 2007;78:177-184.

16. Giannelli M, Formigli L, Lorenzini L, Bani D. Com-bined photoablative and photodynamic diode lasertherapy as an adjunct to non-surgical periodontaltreatment: A randomized split-mouth clinical trial. JClin Periodontol 2012;39:962-970.

17. Giannelli M, Bani D, Viti C, et al. Comparativeevaluation of the effects of different photoablative laserirradiation protocols on the gingiva of periodontopathicpatients. Photomed Laser Surg 2012;30:222-230.

18. Gupta G. Management of gingival hyperpigmentationby semiconductor diode laser. J Cutan Aesthet Surg2011;4:208-210.

19. Hegde R, Padhye A, Sumanth S, Jain AS, Thukral N.Comparison of surgical stripping, erbium-doped:yt-trium, aluminum, and garnet laser; and carbon dioxidetechniques for gingival depigmentation: A clinical

and histological study. J Periodontol 2013;84:738-748.

20. Schulz KF, Altman DG, Moher D; CONSORT Group.CONSORT 2010 Statement: Updated guidelines forreporting parallel group randomised trials. BMC Med2010;8:18.

21. Dummett CO, Gupta OP. Estimating the epidemiol-ogy of oral pigmentation. J Natl Med Assoc 1964;56:419-420.

22. Melzack R. The McGill Pain Questionnaire: Majorproperties and scoring methods. Pain 1975;1:277-299.

23. Bornstein E. Near-infrared dental diode lasers. Sci-entific and photobiologic principles and applications.Dent Today 2004;23:102-108.

24. Giannelli M, Formigli L, Lasagni M, Bani D. A newthermographic and fluorescent method for tuningphotoablative laser removal of the gingival epithe-lium in patients with chronic periodontitis and hy-perpigmentation. Photomed Laser Surg 2013;31:212-218.

25. Lesaffre E, Garcia Zattera MJ, Redmond C, Huber H,Needleman I; ISCB Subcommittee on Dentistry.Reported methodological quality of split-mouth stud-ies. J Clin Periodontol 2007;34:756-761.

26. Cobb CM. Lasers in periodontics: A review of theliterature. J Periodontol 2006;77:545-564.

27. Deppe H, Horch HH. Laser applications in oralsurgery and implant dentistry. Lasers Med Sci 2007;22:217-221.

28. Giannelli M, Bani D, Tani A, et al. In vitro evaluationof the effects of low-intensity Nd:YAG laser irradia-tion on the inflammatory reaction elicited by bacte-rial lipopolysaccharide adherent to titanium dentalimplants. J Periodontol 2009;80:977-984.

29. Domınguez A, Gomez C, Garcıa-Kass AI, Garcıa-Nunez JA. IL-1beta, TNF-alpha, total antioxidativestatus and microbiological findings in chronic peri-odontitis treated with fluorescence-controlled Er:YAGlaser radiation. Lasers Surg Med 2010;42:24-31.

30. Simunovi�c-Soski�c M, Pezelj-Ribari�c S, Brumini G,Glazar I, Grzi�c R, Mileti�c I. Salivary levels of TNF-alpha and IL-6 in patients with denture stomatitisbefore and after laser phototherapy. Photomed LaserSurg 2010;28:189-193.

Correspondence: Prof. Daniele Bani, University of Flor-ence, Department of Experimental and Clinical Medicine,Section of Anatomy and Histology, Research Unit ofHistology and Embryology, Viale G. Pieraccini, 6, I-50139 Florence, Italy. Fax: 39-055-4271-385; e-mail:daniele.bani@unifi.it.

Submitted April 4, 2013; accepted for publication May 21,2013.

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