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International Journal of DentistryVolume 2016, Article ID 8253090, 8 pageshttp://dx.doi.org/10.1155/2016/8253090

Clinical Study-e Use of Narrow Diameter Implants inthe Molar AreaM. Saad, A. Assaf, and E. Gerges

Private Practice Limited to Periodontology andImplantology, Tyre 00961, LebanonUnit of Biomaterials and Technology, School of

Dentistry, Lebanese University, Beirut 00961, LebanonSchool of Dentistry, Beirut Arab University, Beirut

00961, LebanonDepartment of Prosthodontics, School of Dentistry,

Lebanese University, Beirut 00961, Lebanon

Received 23 February 2016; Revised 6 April 2016;Accepted 6 April 2016

Academic Editor: Li Wu Zheng

Copyright © 2016 M. Saad et al. Xis is an open accessarticle distributed under the Creative CommonsAttribution License, which permits unrestricted use,distribution, and reproduction in any medium, providedthe original work is properly cited.

Abstract

Implant rehabilitations in the posterior jaw arein\uenced by many factors such as the condition of theremaining teeth, the force factors related to the patient,the quality of the bone, the maintenance of the hygiene,the limited bone height, the type and extent ofedentulism, and the nature of the opposing arch. Xegold standard is to place a regular diameter implant(>3.7 mm) or a wide one to replace every missing molar.Unfortunately, due to horizontal bone resorption, thisoption is not possible without lateral bone augmentation.In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral boneaugmentation procedures. Xis paper presents a clinicalstudy where NDIs were used for the replacement ofmissing molars. Xey were followed up to 11 years.Special considerations were observed and manyparameters were evaluated. NDI could be used to replacemissing molar in case of moderate horizontal boneresorption if strict guidelines are respected. Yet, futurecontrolled prospective clinical trials are required toadmit their use as scientifc evidence.

1. Introduction

Xere are different defnitions for the narrow diameterimplant (NDI), starting from small body implant,implant with a reduced endosseous diameter, and narrowbody implant to reduced diameter implant. Xe diameteris always less than or equal to 3.5 mm. Originally, its usewas reserved for the replacement of teeth with narrowclinical crowns and/or for limited interdental orinterimplant spaces such as in the upper lateral or lowerincisors areas [1]. As the observed success rate is similarto that of standard diameter implants (SDIs) [2, 3], it issuggested that implant success is not related to implantdiameter. Bone loss around narrow implants was withinthe same limits as those reported around standarddiameter implant [4, 5].

However, NDI fnds another indication for its use,namely, with thin ridges. Indeed, following tooth loss,bone collapses in a three-dimensional pattern. Xehorizontal defciency or width loss develops in a largerextent [6].

Here, the clinician has two options, either to performhorizontal ridge reconstruction procedures (guided boneregeneration, ridge splitting, and onlay bone gran) or toplace an NDI in case of moderate horizontal bone loss[7].

Guided bone regeneration (GBR) is one of the mostdocumented procedures for horizontal boneaugmentation in implant dentistry. Clinical andhistological aspects are well established [8–11]. However,despite the wealth of documentation, it remains asensitive procedure as it depends on many factors suchas the selection of the appropriate bone substitutes,membrane nature (collagen native, cross-linked,resorbable, nonresorbable, etc.) and membrane fxationscrews. Moreover, the need for periodontal plasticsurgery for the reestablishment of keratinized tissue isnot rare aner GBR procedures [12, 13].

Xe other suitable solution to avoid invasive ridgemanagement techniques in cases of limited ridge width isthe use of NDIs [2, 7], therefore broadening theirindications. However, it has been avoided in theposterior jaw for prosthetic and biomechanicalconsiderations. Xe emergence profle of posterior teethis rarely harmonious with a narrow implant neck.Complications are expected to exceed those generallyobserved for the standard diameter implant such asimplant fracture, abutment fracture, screw loosening orfracture, and ceramic fracture [14–17].

Clinical case 1, Figures 1–7 show an NDI placed toreplace a lower molar, with a follow-up period of 2 years

Figure 1: Panoramic X-ray showingteeth loss on the lower 1st molararea.

Figure 2: Narrow diameter implant(3,3 × 12 mm) placed on the lowerlen 1st molar area.

Figure 3: Xenogran to cover theexposed threads.

Figure 4: Panoramic X-ray anerimplant placement.

Figure 5: Periapical X-rayimmediately aner loading.

Figure 6: Periapical X-ray 1 yearaner loading.

Figure 7: Cbct. 2 years aner loading.

Most of the studies that evaluate the survival/success rateof NDIs focus on implants placed in the area of lowerincisor and upper lateral incisor [2]. Only recently hasdata been published regarding the use of NDIs in theposterior jaws, thus, demonstrating an equivalent successrate to standard diameter implants [3, 4, 7, 18–20].

Splinting narrow diameter implants with wider implantsor with natural abutments is one prosthetic modalityreported in many studies. However, it has been observedthat narrow diameter implants used alone could be areliable treatment for posterior jaw or for full mouthrehabilitation [2].

Xe recent systematic review of Assaf et al. [4]demonstrated that implant therapy using NDIs in theposterior jaw is a reliable modality provided that theclinician follows certain guidelines. Implant diameterremains one of many other factors affecting implantsurvival, among which are implant surface and lengthand the osseous quality and the practitioner’s learningexperience curve [7].

It is therefore essential when restoring the posterior jawto understand the complexity of the factors that enhancethe durability of the treatment with small diameterimplants compared to implants of standard diameterplaced aner bone augmentation.

Xis paper is an clinical study in which NDI fromdifferent implant systems was used to replace missingmolars. In that sense, the paper aims at showing theirreliability as an alternative option in the treatment ofmoderately resorbed posterior ridges when lateral boneaugmentation cannot be performed. It is noteworthy thatthe follow-up extends from 1 to 11 years.

2. Materials and Methods

Between 2004 and 2012, eleven NDIs were placed for 10patients who had moderate horizontal bone resorption atmolar edentulous segments. Figure 8 shows patients’distribution according to gender, parafunction, andimplant’s distribution according to the type ofedentulism.

Figure 8: Patient’s distributionaccording to gender, parafunction,and implant’s distribution accordingto the type of edentulism. Ninefemales and 1 male. Nine patientswithout parafunction and 1 withparafunction. Seven out of 11implants were in bounded saddleand 4 in free end saddle.

Xe patients’ medical or/and fnancial statuses were alsoother good reasons for this treatment modality. Xefollow-up period ranged from 1 to 11 years. All implantswere restored with fxed restorations (single crowns orfxed partial dentures). Finally, they were loaded with aconventional loading protocol. Table 1 summarizes allevaluated parameters.

Table 1: Xe different parametersevaluated in our case series. Patientgender (F, female; M, male ), NDIposition in the arch, bonemanagement, type of prosthesis(fxed partial denture = FPD orsingle crown (SC)), loadingprotocol, type of edentulism (F =free end saddle, B = boundedsaddle), splinted to wider diameterimplant, nature of opposing arch,presence of a cantilever, follow-upperiod, and median probing depth.

Inclusion criteria are as follows:

Minimum patient documentations included preoperativeX-ray, post-operative X-ray before loading, post-operative X-ray aner loading in addition to an anotherone 12 months later. Here, it is signifcant to mentionthat all implants were placed by one surgeon.

2.1. Surgical Protocol

Antibiotics (amoxicillin 500 mg TID for 5 days),analgesics, and anti-in\ammatory medication (ibuprofen600 mg TID from 3–7 days, depending on patient need)and chlorhexidine mouth rinse (TID for 7 days) werestarted one day prior to the surgery. Patients were treatedunder strict sterile conditions. Local anesthesia (articainehydrochloridum 7200 mg/1.8 mL, adrenalin 1800 mg/1.8 mL) was provided. Full thickness \apdesigns/surgical protocols were released, NDIs wereplaced according to manufacturers’ recommendations,hemostasis was achieved immediately aner surgery, andpostoperative instructions were given to each patient.

2.2. Final Prostheses Delivery

Final prosthodontics rehabilitations were carried out 2 to6 months aner implant placement, depending on bonequality and NDI initial stability. A fnal pick-upimpression was taken using a special tray. Xeappropriate abutment was selected for each case. Duringthe fnal prosthetic visit, the abutments were torqued to35 Ncm using a dynamometric wrench. Metal-ceramicor metal free crowns were cemented with self-adhesiveresin cement (Rely X Unicem, 3M ESPE, Seefeld,Germany). Special care was given to eliminate anygingival excess of cement material.

2.3. Follow-Up Visits

Patients were recalled for clinical examination visits anerone month and then again aner six months. Aner that,they were recalled once every year up to eleven years. Apanoramic X-ray or an intraoral radiograph was taken toeach implant site by the end of the frst year. Implantsuccess was assessed according to the criteria defned byBuser et al. [15]. In more specifc terms, the implant wasconsidered successful if the following parameters weremet: (1) the absence of recurring peri-implant infectionwith suppuration; (2) the absence of persistent subjectivecomplaints such as pain, the foreign body sensation, ordysesthesia; (3) the absence of a continuous radiolucencyaround the implant; and (4) the absence of anydetectable implant mobility. Xese criteria have provento be effective in defning the success of an implantsystem and evaluating long term results in clinical trials.By considering these outcome measures, all the implantsfollowed in our study were judged according to theirability to satisfy the previously cited criteria, with anobserved success rate of 100%.

Table 1 summarizes all evaluated parameters.

3. Discussion

Narrow diameter implants are commonly used in areaswhere ridge dimensions are narrow or space is limited[22]. Contrary to anterior sites, the clinician’s choice isrestricted to only questionable ridge volume in posteriorsites. Unfortunately, in this area, partial edentulism isusually long-dated and onen preceded by bone lossaround the teeth prior to their loss [23]. Xis challengingcontext complicates or even prohibits the placement ofSDIs unless ridge augmentation is performed. Moreover,when implants are restored, they are submitted to higherlevels of stress than when they would be in the anteriorsites, giving a more critical role to biomechanicalconsiderations [21]. From a pure mechanical point ofview, manufacturers are prompted to improve theresistance of the implants via innovations in designs andmaterials. Lately, studies have shown that NDI madewith titanium-zirconium alloy could be an acceptableoption in compromised cases [19].

Xe success of NDI and the effect of diameter must beconsidered mainly on the long term. Javed and Romanos[16] have shown that the role of implant diameter in longterm survival of dental implants is secondary. In fact, theachievement of primary stability during implantplacement and the patient’s postsurgical hygiene arecritical factors for implant success in the posterior jaw.

Some demanding situations such as reduced ridge widthand patient compromised medical status (patienttolerating only simple surgeries) are challenging to boththe patient and the clinician. Hence, either the implanttherapy has to be disregarded or an NDI has to becomethe only choice.

In case of free end saddle edentulism, NDI could be veryuseful since it provides the only possible fxed solutionvia implant-born restorations. Otherwise, a removablepartial denture becomes a must with its unfavorableeffect to both the residual teeth and the edentulous ridge[19].

Xe improvement of implant macro- and microgeometryhas been another motive for the clinician to select NDIas an available treatment in the molar area. Implantinitial stability and bone implant contact are criticalfactors for implant success, and both are related toimplant macro- and microgeometry [5].

Xe recent systematic review of Assaf et al. [4] showedthat NDI could be used in the posterior jaw underlimited conditions. Xey proposed several surgical andprosthetic guidelines for a safe use.

In our study, 11 NDIs were placed for 10 patients, 9females and 1 male. All were placed in type 2 or 3 boneaccording to the clinician’s tactile evaluation. Xepatients had no signs or symptoms of parafunction,except for one bruxer. Five NDIs were splinted to wider-diameter implants. Two were splinted to another NDI,whereas four were restored with a single crown. Strictocclusal considerations were applied: slight contact incentric occlusion and no contact in lateral movement.

Xe minimum width was 3.3 mm and the minimumheight was 10 mm. All implants used have optimalmacro- and microgeometry.

Surprisingly, the only NDI which was placed to thebruxing patient showed optimal peri-implant bone leveland probing depth aner 11 years of functioning. Xisimplant was placed in bounded saddle adjacent to twostandard diameter implants, all restored with singlecrowns (see clinical case 2, Figures 9–15).

Figure 9: Periapical X-ray showingteeth loss on the lower len secondpremolar, frst and second molar.

Figure 10: Xree implants to replacethe missing teeth, the implantsplaced on the second premolar andfrst molar are narrow diameterimplant (3,5 mm).

Figure 11: Periapical X-ray 6months aner crown cementation.

Figure 12: Clinical situation 7 yearsaner loading.

Figure 13: Centric occlusion.

Figure 14: Clinical situation 11years aner loading.

Figure 15: Panoramic X-ray 11years aner.

4. Conclusion

In case of moderate horizontal bone resorption, NDImay be a reliable option to replace a molar, if thefollowing conditions are satisfed:

Further observational and randomized controlled studiescould provide deeper evidence-based conclusionsconcerning the use of NDI in the posterior jaws.

Competing Interests

Xe authors claim to have no competing interests, eitherdirectly or indirectly, in the products or informationprovided in the paper.

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1 2,3 4

1

2

3

4

(1)(2)

(3)

(4)

(5)

bone thickness between 5 and 7 mm,vertical bone length of 12 mm above the inferioralveolar canal or 10 mm below the sinus allowinga placement of at least 10 mm height NDI,NDI position in bounded molar region or freeend saddle,bone quality type 1, 2, or 3 according to theclassifcation of Lekholm and Zarb [21],NDI with appropriate macro- andmicrogeometry, that is, an external designallowing an acceptable initial stability andoptimal surface preparation to enhance boneimplant contact.

(1)(2)(3)(4)(5)

(6)

bone quality type 1, 2, or 3,minimum implant length of 10 mm,implant protective occlusion,patient with no history of parafunction,implant with appropriate macro- andmicrogeometry,bone thickness between 5 and 6 mm.

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