Replacing a lost molar with one implant represents

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1 Effet of Implnt Dimeter on Reliility nd Filure Modes of Molr Crowns Amilr C. Freits-Júnior, DDS, PhD /Estevm A. Bonfnte, DDS, PhD /Lendro M. Mrtins, DDS, MS / Nelson R.F.A. Silv, DDS, PhD d /Leonrd Mrott, DDS, PhD e /Pulo G. Coelho, DDS, PhD f The reliility nd filure modes of molr rowns supported y three different implnt-supported designs were tested ording to the following groups: group 1, one stndrd-dimeter implnt (3.75 mm); group 2, one nrrow-dimeter implnt (3 mm); nd group 3, two nrrow-dimeter implnts (3 mm). Lods were pplied s mouth-motion yles using step-stress elerted life-testing method. β vlues for groups 1 nd 3 (1.57 nd 2.48, respetively) indited tht ftigue elerted the filure of oth groups, ut not for group 2 (0.39). Autment srew filure ws the hief filure mode. Strength nd reliility were signifintly higher for groups 1 nd 3 ompred to group 2. Int J Prosthodont 2011;24: Repling lost molr with one implnt represents iomehnil hllenge. Funtionl fores re greter in this re, nd lterl fores my led to inresed stress on omponents. 1 Moreover, the presene of limited one width my hinder the plement of wider-dimeter implnt. In this se, rehilittion my involve the plement of one or two nrrow-dimeter implnts or one stndrd-dimeter implnt fter ugmenttion tehniques to provide dequte one dimensions. 1 This study tested ntomilly designed molr rowns supported y one or two nrrow-dimeter implnts or one stndrd-dimeter implnt under sliding ontt ftigue in wter, whih Reserh Sientist, Deprtment of Biomterils nd Biomimetis, Assoite Professor, Postgrdute Progrm in Dentistry, Shool of Dentistry, Potigur University, Ntl, Rio Grnde do Norte, Brzil. Reserh Sientist, Deprtment of Biomterils nd Biomimetis, Assoite Professor, Postgrdute Progrm in Dentistry, Shool of Helth Sienes, Unigrnrio University, Duque de Cxis, Rio de Jneiro, Brzil. Reserh Sientist, Deprtment of Biomterils nd Biomimetis, Assistnt Professor, Deprtment of Restortive Dentistry, Shool of Dentistry, Federl University of Amzons, Mnus, Amzons, Brzil. d Assistnt Professor, Deprtment of Prosthodontis, nd Assistnt Professor, Deprtment of Biomterils nd Biomimetis, New York University College of Dentistry, New York, New York, USA. e Assistnt Professor, Deprtment of Prosthodontis, New York University College of Dentistry, New York, New York, USA. f Assistnt Professor, Deprtment of Biomterils nd Biomimetis, New York University College of Dentistry, New York, New York, USA. Correspondene to: Dr Amilr C. Freits-Júnior, E th Street, Room 804s, New York, NY Fx: Emil:[email protected] hs een shown to reprodue linil filures. 2 The postulted hypothesis ws tht one nrrow-dimeter implnt supporting molr rown would result in lower reliility ompred to either two nrrow- dimeter implnts or one stndrd-dimeter implnt. Mterils nd Methods Eighty-four Ti-6Al-4V implnts (Toureg, Adin Dentl Implnts) were divided into three groups (Tle 1) ording to their width nd restortion design to support molr rown (Fig 1). Implnts were emedded in orthodonti ryli resin poured in 25-mmdimeter plsti tue. Following onnetion of the orresponding proprietry ement-retined utment (RS-3801, Adin Dentl Implnts) to the ering housing, the utment srew (RS-3400, Adin Dentl Implnts) ws tightened ording to the mnufturer s instrutions. A first molr rown ws wxed to the desired ntomy nd st in olt-hromium metl lloy (olt-hrome prtil denture lloy, BEGO) with the ementtion surfe designed to fit either one stndrd-dimeter implnt (group 1), one nrrowdimeter implnt (group 2), or two nrrow-dimeter implnts (group 3) (Figs 1g, 1h, nd 1i, respetively). Crowns were then emented (Rely-X Uniem, 3M ESPE) on the utments. First, men single lod to-filure (SLF) vlues were otined using universl testing mhine (INSTRON 5666). Lod ws pplied using 6.25-mm-dimeter tungsten ride (WC) ll on the mesioul usp (Fig 1f) t rte of 1 mm/min in 30-degree off-xis loding orienttion. Then, sed on the men SLF vlues, three different profiles (mild, moderte, nd ggressive) were designed for mouth-motion stepstress elerted life testing (MMSSALT) (n = 18). Volume 24, Numer 6,

2 Effet of Implnt Dimeter on Reliility of Crowns Figs 1 nd 1 () Nrrow- nd () stndrd-dimeter implnts used in the study. Figs 1 to 1e Autments used in groups () 1, (d) 2, nd (e) 3. Fig 1f Olusl view of the molr rown showing the slight onve fet (red rrow) on the olusl surfe s mens to stndrdize the lotion of lod pplition. d e f g Figs 1g to 1i View of the utment onnetion lotion for molr rowns in groups (g) 1, (h) 2, nd (i) 3. h i j Fig 1j Setup for mehnil tests. Tle 1 Desription of the Study Groups Crowns (n) Implnts Implnt dimensions Group 1 21 Toureg ISP mm Group 2 21 Toureg ISP - NP mm Group 3* 21 Toureg ISP - NP mm *Group 3 hd two implnts per restortion wheres groups 1 nd 2 hd only one. A Servo-All-Eletri system (TestResoures 800L) ws used to simulte mouth-motion (ontt, lod, slide, lift-off) yli loding under wter (lod orienttion nd indenter s in SLF testing). Weiull umultive dmge nlysis (Alt Pro 7, Relisoft) lulted the proility of filure t lod of 200 N (two-sided 95% onfidene ounds). Representtive filed speimens were inspeted using polrized-light stereomirosope (MZ-APO, Crl Zeiss MiroImging) nd snning eletron mirosope (Model S-3500N, Hithi). Results Men SLF vlues were ± N for group 1, ± N for group 2, nd ± for group 3. β* vlues derived from the use-level proility Weiull lultion were 1.57 (1.02 to 2.24) nd 2.48 (1.61 to 3.83) for groups 1 nd 3, respetively, inditing tht ftigue elerted the filure of oth groups. The β vlue of 0.39 (0.24 to 0.62) for group 2 indited tht lod ditted the filure mehnism (Tle 2, Fig 2). The Weiull prmeter ontour plot (Weiull modulus [m] versus hrteristi strength [η = Et]) showed m = 12.7 for group 1, m = 9.4 for group 2, nd m = 14.4 for group 3 (Fig 2). The hrteristi strength ws signifintly higher (P <.05) for groups 1 (η = 469 N) nd 3 (η = N) ompred to group 2 (η = N). Groups 1 nd 3 exhiited signifintly higher reliility thn group 2 (Tle 2). All speimens filed fter MMSSALT testing (Tle 3, Fig 3). Filure nlysis is presented in Figs 4 to 4. *This prmeter desries filure rte hnges over time (β < 1 = filure rte is deresing over time, ommonly ssoited with erly filures or filures tht our due to egregious flws; β ~ 1 = filure rte does not vry over time, ssoited with filures of rndom nture; β > 1 = filure rte is inresing over time, ssoited with filures relted to dmge umultion). 558 The Interntionl Journl of Prosthodontis

3 Freits-Júnior et l Proility of filure (%) Group 1 β = 1.57 Group 2 β = E + 6 Group 3 β = 2.48 Top CB-I Bottom CB-I 1.E + 12 Cyles Fig 2 Use-level proility Weiull lultion for the different groups showing the proility of filure s funtion of yles. F = filure; S = survivl; CB = onfidene oundry. β Et (N) Group 1 Group 2 Group 3 Fig 2 Contour plot (Weiull modulus vs hrteristi strength) for group omprisons. Note the overlp etween groups 1 nd 3, showing no signifintly different hrteristis for strength, lthough oth were signifintly higher thn tht for group 2. F = filure; S = survivl. Tle 2 Clulted Reliility for Mission of 50,000 Cyles t 200-N Lod Output Group 1 Group 2 Group 3 Upper Reliility * 0.99 Lower *Sttistilly signifint differene. Tle 3 Filure Modes After Mehnil Testing Aording to Filure Criteri Used Group 1 Group 2 Group 3 No. of implnt/utment/ srews (eh speimen) SLF MMSSALT Mild (n = 9) Moderte (n = 6) Severe (n = 3) Autment: 3 endings Srew: 9 frtures Autment: 9 totl frtures Srew: 6 frtures Autment: 6 totl frtures Autment: 3 totl frtures Autment: 3 endings Srew: 9 frtures Autment: 9 totl frtures Srew: 6 frtures Autment: 6 totl frtures Autment: 3 totl frtures SLF = single lod-to-frture; MMSSALT = mouth-motion step-stress elerted life testing. Srew: 2 endings, 4 frtures Autment: 4 endings, 2 totl frtures Srew: 18 frtures Autment: 12 prtil nd 6 totl frtures Srew: 1 ending, 11 frtures Autment: 1 ending, 4 prtil nd 7 totl frtures Srew: 1 ending, 5 frtures Autment: 1 ending, 5 totl frtures Disussion MMSSALT elerted the filures of molr rowns supported y one stndrd-dimeter implnt nd two nrrow-dimeter implnts ut not those supported y one nrrow-dimeter implnt, s per β vlues. 3 Ftigue plyed little or no role in the filure of group 2 (β < 1), nd hene, dt were replotted ording to ftigue lod t filure. Weiull modulus (m) nd hrteristi strength were signifintly higher for groups 1 nd 3 ompred to group 2. m is n inditor of strength reliility nd the symmetri strength distriution s Volume 24, Numer 6,

4 Effet of Implnt Dimeter on Reliility of Crowns d e f Fig 3 Filure modes of group 3 speimens fter mehnil testing: () intt srew, () srew ending, ( nd d) srew frture lolized in the trnsition re from the smooth to the threded surfe, (e) intt utment, (f) utment ending, nd (g nd h) utment prtil nd totl frture, respetively. g h Compression url Fig 4 Representtive snning eletron mirosopi imge of srew frture. The white rrows (eh mrks) nd the ovl dotted white line (ompression url) show typil mrks inditing the diretion (lk rrow) of rk propgtion from lingul to ul. The red rrow shows the site of frture origin. Figs 4 nd 4 Mgnifitions of utments in () light-polrized nd () snning eletron mirosopes. The red rrows indite the srew mrk held in the internl surfe of the utment. The white rrows show ompression urls, lso inditing the diretion (lk rrow) of rk propgtion from lingul to ul. result of flws within the mteril. 4 A higher m indites smller or fewer defets (greter struturl reliility), nd lower m is evidene of greter vriility of the strength, refleting more flws in the system nd derese in reliility. 4 The reliility lulted in this study indited this reltionship with signifintly lower perentge of rowns supported y one nrrow-dimeter implnt (group 2) surviving, ompred to oth one stndrd-dimeter implnt (group 1) nd two nrrow-dimeter implnts (group 3). 560 The Interntionl Journl of Prosthodontis

5 Freits-Júnior et l Autment srew frture ws oserved in ll rowns supported y one implnt, whih is in greement with the prostheti filure modes reported linilly. 5 Although the use of one nrrow-dimeter implnt to support rowns provides n lterntive to liniins in res where one volume is limited, ution in the olusl design of prosthetis, suh s redution of the olusl tle nd usp inlines, n e suggested to minimize off-xis fores. However, if two nrrow-dimeter implnts re indited, 12-mm spe etween implnts is required. 1 Implnts lso should e pled s prllel s possile to llow pssive fit for the emented rown. Otherwise, ngulted utments my e used s n lterntive to orret the mislignment. Conlusion The hypothesis tht the reliility of molr rowns supported y one nrrow-dimeter implnt ws lower thn tht of one stndrd-dimeter implnt or two nrrow-dimeter implnts ws onfirmed. Aknowledgments The uthors knowledge the dontion of study smples y Adin Dentl Implnts nd thnk CNPq-Brzil nd Mrott Dentl Studio for their support. Referenes 1. Blshi TJ, Hernndez RE, Pryszlk MC, Rngert B. A omprtive study of one implnt versus two repling single molr. Int J Orl Mxillof Implnts 1996;11: Coelho PG, Bonfnte EA, Silv NR, Rekow ED, Thompson VP. Lortory simultion of Y-TZP ll-ermi rown linil filures. J Dent Res 2009;88: Aernethy RB. Reliility nd sttistil nlysis for prediting life, sfety, survivility, risk, ost nd wrrnty lims. In: Aernthy RB. The New Weiull Hndook. North Plm Beh, Florid: Dr Roert Aernethy, 2004: Ritter JE. Prediting lifetimes of mterils nd mteril strutures. Dent Mter 1995;11: Cho SC, Smll PN, Elin N, Trnow D. Srew loosening for stndrd nd wide dimeter implnts in prtilly edentulous ses: 3- to 7-yer longitudinl dt. Implnt Dent 2004;13: Literture Astrt Estheti outomes with porelin-fused-to-ermi nd ll-ermi single-implnt rowns: A rndomized linil tril The im of this rndomized ontrolled tril ws to ompre the ojetive nd sujetive estheti outomes of two types of srewretined single-implnt rowns. Twenty ptients were rndomly ssigned to two groups: For the ontrol group, srew-retined porelin-fused-to-metl rown ws frited; ptients in the test group reeived srew-retined ll-ermi rown. Ptients were followed-up with t seline (B; 2 months fter implnt plement ut efore prosthodonti tretment), 2 weeks fter rown insertion (CI), 1 yer fter CI (1Y), nd 2 yers fter CI (2Y). At eh follow-up ppointment, the following ojetive mesurements were reorded: mesil nd distl ppill height (PH), linil rown height t the implnt site (CLi), linil rown length t the djent teeth (CLt), width of kertinized muos t the implnt site (KMi) nd djent teeth (KMt), first one-to-implnt ontt (FBIC), full-mouth plque sore (FMPS), nd full-mouth leeding sore (FMBS). A pink estheti sore (PES) nd white estheti sore (WES) were lulted for oth study groups. In ddition, nine expert liniins not involved in the tretment nd investigtion were sked to visully inspet stndrdized introrl photogrphs nd to sujetively determine whether the rowns were ll-ermi or porelin-fused-to-metl. The ojetive nd sujetive prmeters etween the groups t B, CI, 1Y, nd 2Y nd differenes etween eh study time point were nlyzed using the Mnn-Whitney U test. The signifine level ws set t P.05. A pired t test ws used to ompre the PES nd WES, with the signifine level set t P =.05. No implnt or utment filures were reorded during the entire length of the study. There were no sttistilly signifint differenes for PH, CLt, CLi, KMi, KMt, FMPS, FMBS, nd FBIC t ll time points, exept FMPS t 2Y. Out of mximum sore of 20 for PES nd WES, the porelin-fused-to-metl nd ll-ermi groups sored men vlue of nd 13.12, respetively, with no sttistilly signifint differenes etween sores. The expert liniins ility to orretly determine the rown type for oth groups ws not signifintly different from the vlue tht would e expeted from rndom guessing. The uthors orretly onluded tht without speifi estheti prmeters suh s tooth morphology, interproximl ppill, nd level of ervil mrgins, the implnt rown mteril lone would not e suffiient to ensure n optiml estheti outome. Gllui GO, Grütter L, Nedir R, Bishof M, Belser UC. Clin Orl Implnts Res 2010;22: Referenes: 20. Reprints: Dr Germn O. Gllui, Deprtment of Restortive Dentistry nd Biomterils Sienes, Hrvrd Shool of Dentl Mediine, Hrvrd University, 188 Longwood Avenue, Boston, MA, USA. Emil: [email protected] Elvin W.J. Leong, Singpore Volume 24, Numer 6,