In vitro retention force measurement for three different attachment systems for implant retained overdenture

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1 Originl Article In vitro retention force mesurement for three different ttchment systems for implnt retined overdenture Kreem Mohmmed Red, Irhim Rmdn El Torky 1, Mohmed Neel EL Gendy 2 Deprtment of Prosthodontics, Menoufi University Hospitls, Shiin l Kwm, Menoufi Governorte, 2 Deprtment of Prosthodontics, Fculty of Dentistry, Tnt University, Tnt, Ghri Governorte, Egypt, 1 Deprtment of Prosthodontics, College of Dentistry, Al Jouf University, Skkh, Sudi Ari Astrct Aim: The im of this study is to compre the retention force of three different types of overdenture ttchment systems used in implnt retined mndiulr complete overdentures. Mterils nd Methods: Twenty one similr crylic resin locks were prepred nd divided into three study groups: Group A (snp ttchment) 10 specimens, Group B (loctor ttchment) 1 specimen, nd Group C (syncone ttchment) 10 specimens. A single rectngulr het cure crylic resin lock with two implnt nlogs 22 mm prt ws used with ll specimens. Ech specimen ws sujected to 5500 cycles of insertion nd removl in the presence of rtificil sliv, representing 5 yers of usge. Retention ws mesured three times for ech specimen using universl testing mchine. Dt were nlyzed using one wy nd two wy nlysis of vrince t 95% level of confidence. Results: Loctor ttchment group (Group B) showed the gretest retention level throughout the study, followed y snp ttchment (Group A), nd syncone ttchment (Group C) showed the lowest retention level. Conclusion: Regrdless of the initil retention level of overdenture ttchment, grdul loss of retention vlues is inevitle. However, the rte of retention loss in overdenture ttchments is higher in types which comprised plstic prts within their components, rther thn those totlly mde up of nole metls. Key Words: Ftigue strength, loctor, overdenture ttchment, retention force, snp, syncone Address for correspondence: Dr. Kreem Mohmmed Red, Deprtment of Prosthodontics, Menoufi University Hospitls, Shiin l Kwm, Menoufi Governorte, Egypt. E mil: kreem38782@dent.tnt.edu.eg Received: 21 st Octoer, 2015, Accepted: 30 th My, 2016 INTRODUCTION Mny edentulous ptients re stisfied with their conventionl complete dentures lthough some often encounter prolems with this design. These prolems included poor stility nd retention of the prosthesis, pin during mstiction, nd decresed chewing efficiency. Severl clinicl studies hve shown tht these prolems Quick Response Code: Access this rticle online Wesite: ips.org cn e successfully ddressed using dentl prosthesis employed in conjunction with dentl implnts in implnt supported or implnt retined overdentures. [1] The concept of overdentures originlly involved fixing mechnicl ttchments to teeth roots to enhnce retention nd stility of conventionl dentures. In This is n open ccess rticle distriuted under the terms of the Cretive Commons Attriution NonCommercil ShreAlike 3.0 License, which llows others to remix, twek, nd uild upon the work non commercilly, s long s the uthor is credited nd the new cretions re licensed under the identicl terms. For reprints contct: reprints@medknow.com DOI: / How to cite this rticle: Red KM, El-Torky IR, EL-Gendy MN. In vitro retention force mesurement for three different ttchment systems for implnt-retined overdenture. J Indin Prosthodont Soc 2016;16: The Journl of Indin Prosthodontic Society Pulished y Wolters Kluwer - Medknow

2 Red, et l.: Retention force mesurement for three different ttchment systems recent yers, vrious ttchments systems hve een successfully used with removle implnt overdentures. [2 4] Snp ttchment is one of the ll nd socket types of ttchment. The utment of snp ttchment (the mle prt) is screwed over the implnt fixture. on the other hnd, the femle prt is fixed in the fitting surfce of the overdentue. The loctor ttchment ws introduced in 2001 nd does not use the splinting of implnts. This ttchment is self ligning, hs dul retention through oth externl nd internl mting surfces, [5,6] resilient, durle, nd hs some uilt in ngultion compenstion. [7] Telescopic type of removle prostheses with immedite loding hs een used in the edentulous or prtilly edentulous mndile. [8,9] Previous investigtions of ttchments re in greement tht loss of retentive force over time is inevitle. This loss of retention hs een ttriuted to wer of ttchment components. [2] Comprison of the retentive cpcity of the previously mentioned overdenture ttchments over time will e discussed in detils in our study. In our null hypothesis, there is no difference in the retention mong the three types of ttchment. MATERIALS AND METHODS Preprtion of nlog se lock In our study, single rectngulr het cure crylic resin (Acrostone Mnufcturing nd Import Co, Ciro, Egypt), se lock with the dimensions of 4 cm in length, 2 cm in width, nd 3 cm in height, hd een constructed. The nlog holes were prepred 22 mm prt from ech other y the id of n crylic stent to ensure prllelism nd void discrepncies rise from mislignment of ttchment components which ccelertes wer mechnisms. [3,10,11] It ws mde of cler het cure crylic resin (Acrostone Mnufcturing nd Import Co., Ciro, Egypt) with the sme length (4 cm), width (2 cm), ut of lower thickness (1 cm) with two verticl metl sleeves instlled prllel to ech other y id of the surveyor (Ney Surveyor, Dentsply, NY, USA), 22 mm prt from ech other. Holes were mde so tht the top of the two implnt nlogs (Ankylos, Dentsply Frident, Mnnheim, Germny) 4 mm in dimeter, 12 mm in length ws 1 mm elow the top surfce of the se lock. A cold cure crylic resin (Acrostone Mnufcturing nd Import Co., Ciro, Egypt) ws used to sel the spce etween the nlog nd side wlls of the drilled hole. Het cure crylic resin cylinder 5 cm length, 1 cm dimeter ws prepred. A wide hole ws prepred in the undersurfce of the se lock to ccommodte dimensions of the crylic resin cylinder with sufficient room for cold cure crylic resin for fixtion of the crylic cylinder in the se lock [Figure 1]. Preprtion nd grouping of overdenture simulting locks Twenty one het cure crylic resin locks 4 cm in length, 2 cm in width, nd 2 cm in height were prepred nd divided into s follows. Figure 1: The crylic cylinder fixed to the ottom of the crylic se lock Group A: Including ten locks tht were used for snp ttchment (Ankylos, Dentsply Frident, Mnnheim, Germny) Group B: Including single lock used for loctor ttchment (Zest Anchors Inc., for Ankylos, Dentsply Frident, Mnhiem Germny) group, due to the interchnging cpcity of the nylon mle, this single lock hd een used for ten smples y chnging the nylon mle fter ech full cycle of mesurement Group C: Including ten locks tht were used in syncone ttchment (Ankylos, Dentsply Frident, Mnnheim, Germny), Telescopic crown, group (contined secondry crowns of syncone ttchment). Following mnufcturer instructions of different ttchment types, direct pick up technique ws used for instlling of ttchment components (utments nd denture prt) in the three study groups. Retention force mesurement We dopted the methodology utilized y mny other studies s Gmoren et l., [12] Fromentin et l., [13] Boteg et l., [14] d Fontour Frsc et l., [15] Brnchi et l., [16] nd Evtimovsk et l. [6] for evlution of retention force of the selected ttchments. The Instron universl testing mchine ws used to mesure the retention forces. The nlog se lock ws ttched to the lower comprtment of the universl testing mchine while overdenture simulting locks were ttched to the upper comprtment of the mchine. To mintin the presence of sliv throughout the testing process, the se lock remined in the ottom of plstic deep pool while the verticl cylinder penetrtes the ottom of the pool to e ttched to the lower comprtment of the universl testing mchine. Adhesive silicone ws used to sel minor spces etween the cylinder se lock joint nd the ottom of the pool. The pool ws filled The Journl of Indin Prosthodontic Society Oct-Dec 2016 Vol 16 Issue 4 381

3 Red, et l.: Retention force mesurement for three different ttchment systems y rtificil sliv (Xerotin Artificil Sliv, UK, 1.5 mm C, 3.0 mm P, 20.0 mm NHCO3, ph 7.0) to level ove the top of the se lock y out 2 mm [Figure 2 nd ]. Dislodgement of the locks contining denture prts of the three ttchments ws performed using the universl testing mchine prllel to the long xis of the implnt nlogs. The crosshed speed ws djusted t 50 mm/min s this hs een reported to pproximte the speed of the movement of the denture wy from the ridge in vivo. [17,18] The Instron universl testing mchine controlled y computer to interfce the (Bluehill, ITW Inc., Englnd) softwre ws used to pply mximum seting nd dislodging forces for ech specimen t cross hed speed of 50 mm/s. It ws progrmmed to pply 5500 cycles of displcement nd insertion of 4 mm mgnitude of movement t frequency of 12 cycles/min. Retention forces were clculted three times (initilly, fter 3000 nd 5500 cycles). A specimen ws considered filed if showed seprtion etween ttchment components nd over-denture simulting locks, or seprtion of ttchment components itself. Digitl light microscopy exmintion Using digitl light microscope (Celestron, LLC., Torrnce, CA, USA), rndomly selected denture prts of ll ttchments hd een exmined using the sme oject lens distnce (13 mm) nd the sme mgnifiction ( 40) hd een used for ll specimens. Sttisticl nlysis Dt re presented s mens nd stndrd devitions (SDs); the level of significnce ws set t 0.05 for ll tests. Dt nlysis ws performed using the sttisticl softwre SPSS 16.0 (SPSS Inc., Chicgo, IL, USA) for Windows. Sttisticl nlysis ws performed using one wy nlysis of vrince t 95% level of confidence whenever sttisticl significnt difference ws recorded mong different tested groups, Tukey Krmer post hoc test ws performed to mke pirwise comprisons etween ech two significnt difference groups or sections. RESULTS Tle 1 shows men ± SD of retention levels recorded t different numer of cycling in ech study group nd percent chnge of retention vlues from retention vlue recorded initilly within the sme group [Figure 3]. Neither of the specimens hd reported filure t ny stge of the study. In comprison of retention vlues of different systems t the sme numer of cycling, ll systems were significntly different from ech other, where loctor ttchment group showed the gretest retention vlues followed y snp ttchment, nd syncone ttchment group showed the lowest retention vlues throughout the study. In comprison of retention level chnges in ech group fter different numer of cycling, the retention of snp ttchment group significntly decresed y % from retention levels recorded initilly fter 5500 cycles. Retention of loctor ttchment group significntly decresed y % nd % from retention levels recorded initilly fter 3000 nd 5500 cycles, respectively. However, there ws no sttisticlly significnt difference in retention levels recorded t different stges of mesurement. Digitl light Tle 1: Men±stndrd devition of retention levels recorded throughout the study nd percent chnge in retention throughout the study Study group Group A (snp ttchment) Group B (loctor ttchment) Group C (syncone ttchment) Bseline retention Stge After 3000 cycles After 5500 cycles ± ± ±3.676* % % ± ±6.117*, ±6.294*, % % 12.08±0.874, ±1.178, ±1.264, 4.909% 9.139% *Significnce with seline retention vlue (within the sme row),, Significnce with Groups A nd B, respectively (within the sme column). Significnce ws set to e when P<0.05, : Decrese in the recorded vlue Figure 2: () Overview of specimen mounted in the Instron. () A closer view Figure 3: Chnges in retention level during different stges of the study 382 The Journl of Indin Prosthodontic Society Oct-Dec 2016 Vol 16 Issue 4

4 Red, et l.: Retention force mesurement for three different ttchment systems microscopy exmintion reveled distortion of nylon insert of loctor ttchment [Figure 4] loss of surfce texture of snp ttchment [Figure 5] nd miniml chnges in surfce chrcteristics of syncone ttchment system [Figure 6]. DISCUSSION Using complete dentures is chllenge ecuse of decrese of force nd muscle coordintion nd difficulty in chieving n cceptle level of prosthesis retention nd stility due to one resorption.[19,20] In this study, we simulte the use of only two implnt nlogs instlled in crylic resin lock for stiliztion of the lower denture to provide relile nd predictle tretment outcomes. c Figure 4: Nylon mle prt () efore cyclic removl nd insertion, () fter 3000 cycles, (c) fter 5500 cycles c d Figure 5: Chnges in snp femle t different levels of cycling: () Snp femle t the eginning, () fter 3000 cycle, (c) fter 5500 cycles, (d) fter 5500 cycles closer view from inside It is regrded s the minimum stndrd of cre for completely edentulous ptients.[21,22] These nlogs were 22 mm prt s it hd een reported tht nturl cnines re seprted y the sme distnce.[23] On the other hnd, Douks et l. stted tht there re no stndrdized rules for the idel distnce etween ttchments to chieve optimum retention.[24] Trditionl Instron (IS) testing mchines re the most common instrument used to replicte the verticl seprtion of the denture from the mouth.[25] It hd een ccepted s relile nd vlid instrument to test pek lod forces in vitro.[17,26 28] There is no consensus in the literture considering numer of cycles should different specimens sujected to, where different numer of cycles hd een used in different studies; for exmple, 10,000[29] 5500[12,14,30] 3000,[15,31] or 14,600 cycles.[32] In this study, the numer of cycles to which specimens were sujected ws 5500 cycles corresponds to 5 yers usge of dentures considering verge three removls per dy, which is considered long enough for prosthesis replcement.[28] Ftigue or filure of overdenture ttchments dversely ffects their function, mintennce, nd ptient stisfction.[33] After n pproprite numer of insertion removl cycles, ttchments otin more stle retentive properties, which represent the postinsertion period.[34] Accordingly, this study compred retentive properties of the ttchments in this postinsertion period nd not to limit it to the initil ssessment only.[25] The presence of rtificil sliv t room temperture ws mintined throughout the study to simulte wet orl environment to sufficiently form protective nd luricnt lyer etween ttchment components.[35] On the other hnd, the principle of the use of luricnt is n ccepted stndrd for wer simultion systems.[29,30,36] On the other hnd, the composition nd temperture of sliv could lso influence the results, minly if one considers the susceptiility of polymeric components to sor wter.[14] c d Figure 6: Chnges in syncone secondry crown t different levels of cycling: () Syncone secondry crown t the eginning, () fter 3000 cycle, (c) fter 5500 cycles, (d) fter 5500 cycles closer view from inside The three ttchment systems under evlution met the minimum vlue of 5 N, required for the stility of overdenture throughout the study.[14,15] On the other hnd, the loctor ttchment showed significntly higher retention vlues thn the other systems. The loctor ttchment greter retention hd een reported in mny previous studies.[15,37,38] This could e ttriuted to tht loctor ttchment hs dul retention feture tht mens the mle prt will retin on the inside nd outside of the The Journl of Indin Prosthodontic Society Oct-Dec 2016 Vol 16 Issue 4 383

5 Red, et l.: Retention force mesurement for three different ttchment systems utment. [39] Moreover, the greter cross section of the loctor ttchment increses surfce re ville for frictionl contct etween components of these ttchments. [39] However, regrdless of the high retention vlues recorded t the eginning of the study, loctor ttchment showed the gretest decrese of retention overtime which is in greement with mny previous reports. [18,32,40] This could e ttriuted to wer nd plstic deformtion of the nylon inserts. [32,41] Such findings hd een proved y digitl microscopy exmintion of nylon mle prts t different stges of the study [Figure 4]. Snp ttchment showed lower retention level thn loctor ttchment. This could e ttriuted to greter resiliency of ll ttchment, resulting in lower initil retention forces. [15] An dditionl mechnism descried to interpret the greter retention forces of loctor ttchment is tht ll ttchments re inserted with minimum pressure while in cse of loctor, higher effort for proper position of overdenture is needed nd ptients iting force is not sufficient; hence, imnul press on is necessry. Consequently, higher forces to drw off the overdenture is required. [38] However, despite the lower retention of snp ttchment, it did not decrese significntly except fter 5 yers of usge which hd een confirmed y light microscopy [Figure 5]. This could e ttriuted to tht the femle prt is mde of nole metl lloy with high percentge of gold tht hs gret mlleility nd ductility nd promotes the dpttion nd mintennce of the retention forces, eing in ccordnce with Byer et l., who lso found greter retention forces for metl components tht mintined for longer period. [36] The lowest retention vlues of syncone overdenture ttchment s shown in Tle 1 could e ttriuted to tht it depends only on friction of fcing smooth surfces [42] with no dditionl mens of retention like the other two types of ttchment in our study. Our results re supported y studies of mny uthors who stted tht the tpered telescopes exhiit friction only when completely seted; s soon s the outer crown is dislodged even slightly from the terminl position, retention of the system is lost voiding undue forces on the utment. [42,43] In contrst to loctor ttchment nd snp ttchment, syncone overdenture ttchment system showed stle retentive properties in concurrence with Zhng et l. in 2008, who found tht the retention forces of nkylose syncone conicl crown system where lmost constnt during the entire testing which involved 5000 insertion removl cycle. [37] Another in vivo study confirmed tht fter 30.3 months of usge, conicl crown concept offers stle complete denture retention. [44] The sttisticlly similr vlues otined from the eginning to end of the tests in this cse resulted from the comintion of oth utment nd retention component mde of nole metl lloy. Further confirmtion of such finding hd een reveled form light microscopy exmintion of secondry crowns of syncone ttchment system reveled very little chnge in surfce chrcters nd orders [Figure 6]. CONCLUSION Within the limittions of the present in vitro study, the results suggested tht All systems evluted showed retention vlues higher thn 5 N, the minimum required for stilizing the prosthesis, eing considered suitle for clinicl use The loctor ttchment system showed higher retention vlues thn snp nd syncone ttchment Retention loss is inevitle in ll types of ttchment due to different mechnisms; however, the rte of loss vries ccording to ttchment components s well s the mode of ttchment retention The rte of retention loss in overdenture ttchments ws higher in ttchment types which comprised plstic prts within their components, rther thn those totlly mde up of nole metls. Finncil support nd sponsorship Nil. Conflicts of interest There re no conflicts of interest. REFERENCES 1. Chen YF, Yng YH, Lee JH, Chen JH, Lee HE, Chou TM. Tongue support of complete dentures in the elderly. Kohsiung J Med Sci 2012;28: Alseeh NH, Pyne AG, Swin MV. 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Quintessence Int 2010;41: The Journl of Indin Prosthodontic Society Oct-Dec 2016 Vol 16 Issue 4 385