Comparison of Retentive Force in Four Attachment Systems in Implant- Supported Overdenture of the Lower Arch

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1 Originl Article Comprison of Retentive Force in Four Attchment Systems in Implnt- Supported Overdenture of the Lower Arch Ahmdzdeh A., Fereidoonpoor N. Dept. of Prosthodontics, School of Dentistry, Ahwz University of Medicl Sciences, Ahwz, IRAN KEY WORDS Attchment; Overdenture; Retention Received Oct. 2011; Received in revised form April 2012; Accepted April 2012 ABSTRACT Sttement of Problem: Along with the rpid popultion growth in recent decdes, there hs been n increse in the number of edentulous ptients who hve complictions with conventionl denture. This entils the use of dentures, such s implnt overdenture, which re more efficcious. Purpose: The purpose of this study is to compre four types of different ttchment systems; two prefbricted nd two cstble ttchments. Mterils nd Method: A model of lower edentulous rch ws constructed out of dentl stone. Two prllel implnts were plced in the cnine region. A single cst metl chrome coblt frmework ws fbricted to provide reinforcement for experimentl overdentures nd it splinted the two ttchments on the cst. To conduct this study, four groups with six numbers of ttchments in ech group (superflex bll, loctor, cstble bll on br, cstble br) were selected. All the smples were put in Universl Testing Mchine nd tension force with the speed of 50 mm/ min ws exerted to seprte the frmework from the cst. The tension force ws recorded nd the first two prefbricted ttchments (superflex bll nd loctor) were compred with the second two cstble ttchments (bll on br, cstble br). Results: The findings of this study reveled tht retention force of cstble bll on br ws greter thn the other three ttchments (35.31±3.14N). With regrd to the strength of retentive force, superflex bll took the second plce (33.33± 3.11 N) nd loctor (20.90± 3.74N) nd cstble br (14.74± 1.15N) took the third nd the forth plces, respectively ( p <0.001). Conclusion: The retentive force of cstble bll on br ws similr to tht of superflex bll. Therefore, the use of this chep ttchment; cstble bll on br, is preferred to its prefbricted counterprts. The retentive force of this kind of ttchment is greter thn expensive loctors. The retentive force of cstble br ws similr to tht of loctor, lthough the former ws bit weker thn the ltter. Therefore, when less retention is needed, cstble br cn be suitble choice, nd when more retention is needed, cstble bll on br is preferble. * Corresponding uthor. Fereidoonpoor N., Dept. of Prosthodontics, School of Dentistry, Ahwz University of Medicl Sciences, Ahwz, IRAN Tel: Emil: njmeh.fereidoonpoor@yhoo.com Introduction The constnt improvement in the stndrd of hygiene hs led to high life expectncy mong people. The verge ge of the elderly hs lso incresed [1-3]. As people become older, the need for orl hygiene is much more felt. Unfortuntely, however, edentulism hs incresed in Irn not only in the elderly but lso in the youth nd it cn be due to systemic diseses; indequte helth cre, especilly in smokers; drug buse; no periodic visit of dentist; nd no dentl 54

2 Comprison of Retentive Force in Four Attchment Systems in Implnt- Supported Overdenture Ahmdzdeh A. insurnce. There is need to replce lost teeth in order to repir the defects, such s chewing disturbnce; indigestion; speech disturbnce; nd esthetic [4]. There re mny wys to this end. Perhps, the first choice cn be the conventionl complete denture for both the upper nd the lower jws, but this leds to mny problems, such s ridge resorption; nuse; stbility; nd retention deficiency nd mkes both ptients nd dentists go to fixed tretment options, such s implnt fixed prosthesis. But due to the high level of costs nd extensive surgery, especilly in old ptients with mny systemic diseses, this type of tretment is not recommended [5-9]. Overdentures solve mny of, the bove mentioned, problems with fixed prosthesis. Implnt overdentures connect to implnt fixtures with component stte such s ttchment [10]. This component consists of two prts: mle nd femle [11]. Attchments cn be divided into mny types, only on the bsis of their differences in flexibility, csting precision, production process, geometricl shpe nd cross section. Shfie, with regrd to cross section, divided ttchments into the following types: 1. Clips nd brs, 2. Studs, 3. Mgnets, 4. telescopic coping [12]. Furthermore, precision nd semiprecision re two types of ttchments with regrd to production process nd joint nd unit re two other types with regrd to flexibility [13]. The purpose of this study ws to compre the retentive force in four ttchment systems in implntsupported over denture of the lower rch. If retentive forces of both cstble nd prefbricted ttchment re similr, the former cn be used becuse it is more vilble nd cheper thn the ltter. The most usble prefbricted ttchments in Irn re loctor nd superflex bll, nd cstble ttchments which include cstble br nd cstble bll on br [14]. Chung compred the retention force of different colors of superflex bll nd loctors. The results of the study indicted tht retention force of superflex bll nd Loctors were lmost equl [15]. Boteg (Percicb university, Brzil) compred retention nd ftigue resistnce of four kinds of overd enture ttchments (two kinds of superflex bll nd two kinds of prefbricted br clip). Finlly, it ws stted tht retention forces of br clip nd superflex bll were equl [16]. Sdig study mentioned tht Loctor retention ws more thn bll [17]. Fu et l., compred retention force of three prefbricted nd two mchine milling ttchments. Their findings indicted tht retention forces of ll groups were nerly equl fter the first tension cycle [18]. Mterils nd Method In this study model of lower edentulous rch ws constructed in dentl stone (Louisville, KY Dentl Stone, Whip Mix Corp., Resin Rock). All edentulous ridge undercuts were eliminted. Two prllel implnts (ITI System, Strumnnco, Switzerlnd) with mm were plced in the cnine region with distnce of 22mm between them. A single cst metl chrome coblt frmework (Wironium, BEGO Herbst Co, Bremen, Germny) ws fbricted to provide reinforce-ent for experimentl overdentures. The cst metl frmework lso possessed four withdrwl loops tht were engged during direct pull-off testing (Fig. 1).Then two superflex bll ttchments (Rein Co., Itly) were inserted in the implnts (Figure 1). Figure 1 The cst metl frmework possessed four withdr-wl loops tht were engged during direct pull-off testing (white rrows).then two superflex bll ttchments were inserted in the implnts. Figure 1b Self-cure crylic resin ws plced over the housi-ngs nd it splinted the two ttchments on the cst. After tht, first the pink rubber cp nd then the metl housing were inserted into ttchments with 0.4 mm distnce between them. Self-cure crylic resin (Densply Interntionl Inc., Co.) ws plced over the housings nd splinted the two ttchments on the cst (Figure 1b).All of these were lso done for the two loctors (Strumnn Co., Switzerlnd), i.e. with the pink rubber cp nd the metl housing nd with 0.4 mm distnce between cp nd housing on the cst. The cstble plstic hder br (Rein Co., Itly) ws wxed up between the two implnts in contct with nt ridge. Then plstic hder br ws csted (Figure 2) nd two yellow plstic clips were inserted into the br (Figure b 55

3 2b). After tht, self-cure crylic resin ws put over the ssembly. forces. Pek lod-to-dislodgement nd strin-tdislodgement were recorded nd clculted from stress-strin curves in order to determine the retention force nd the chnge of distnce between the ptrix nd the mtrix of ech ttchment system. Figure 2 Plstic hder br ws csted 2b Two Plstic clips were inserted into br. The cstble plstic bll on br (Rein Co., Itly) with two blls on br nd the pink rubber cps nd the metl housings nd with 0.4 mm distnce between the cps nd the housings, ws wxed up between the two implnts in contct with nt ridge nd csted into metl form, putting plstic cps nd housings nd selfcure crylic resin, too (Figure 3). b Dt nlysis One-wy nlysis of vrince (ANOVA) ws run to nlyze the dt (SPSS16), while Tukey post-hoc tests were used for pir wise comprisons (α=0.05). (1 Z1 B)2( 1 2)2 N 2 ( )2(3.4 2)2 N ( 1 2) (4.5) Results Bsed on the findings of this study, retention force of cstble bll on br ws greter thn other ttchments (35.31±3.14N). Superflex bll took the second plce in this regrd (33.33±3.11 N). Loctor (20.90±3.74N) nd cstble br (14.74± 1.15N) were t third nd forth plces, respectively ( p <0.001) (Figure 4 nd Tble 1). Figure 3 The cstble plstic bll on br ws wxed up between the two implnts which were in contct with nt ridge. The retention force (Newton) Superflex bll Lctor Cstble br Cstble br on bll The nme of ttchments tht were evluted Mchine screws were incorported into the cst metl frmework so tht overdenture housing, contining different ttchments, could esily be secured nd removed during testing. Of course, before inserting this ssembly in the mchine, the cst ws trimmed becuse it ws too big to be inserted in the mchine. Overll, 24 overdentures were fbricted nd six specimens of ech of ttchment system were tested. Retentive force for ech of experimentl overdentures ws exerted t cross-hed speed of 50 mm/min. This cross-hed speed hs been reported to pproximte the cliniclly relevnt movement of the denture wy from the edentulous ridge. A metllic chin connected the Universl Testing Mchine (Technologicl Model 5T, Chin Mteril Co., Tipei, Tiwn) to the overdenture frmework t the withdrwl loops. Verticl testing forces simulted nticipted overdenture removl Figure 4 Comprison of Retentive Force in Four Attchment Systems in Implnt -Supported Overdenture Tble 1 Comprison of Retentive Force in Four Attchment Systems in Implnt -Supported Overdenture (mximum minimum rnge nd stndrd devition) Nme of ttchments Mx Min SD Cstble bll on br Superflexbll p = p < Lctor p < Cstble br Superflexbll Lctor 36.6 p < Cstble br Loctor p = Cstble br Cstble br Discussion Cstble bll on br hd lmost similr retention to superflex bll. So, this chep ttchment cn be used insted of the prefbricted ones in indicted ptients. Retention of this ttchment ws more thn expensive 56

4 Comprison of Retentive Force in Four Attchment Systems in Implnt- Supported Overdenture Ahmdzdeh A. loctor, too. Cstble br ttchment ws less retentive thn loctor but the difference ws not so much. In the present study, before inserting this ssembly in the mchine, the cst ws trimmed, becuse it ws too big to be inserted in the mchine. In summry, it cn be sid tht when less retention is needed, cstble br cn be suitble option nd when more retention is needed cstble bll on br. The results of this study re in greement with some other studies, few of which will be mentioned below. Chung compred the retention forces of different colors of superflex bll nd loctors. An edentulous mndibulr model ws constructed through incorporting two prllel 4.0 mm x 13 mm, Brnemrk, implnts which were plced in the cnine regions. Attchments were embedded in metl-reinforced experimentl overdenture, designed to be dislodged from the model by Universl Testing Mchine. Tensile dislodging force ws exerted on the overdenture t crosshed speed of 50 mm/min. Then, five overdentures were constructed for ech of the ttchment systems. The evluted ttchments were Hder br & metl clip, Loctor LR pink, Loctor LR white, Spheroflexbll, Shiner mgnet, Mxi mgnet, Mgnedisc mgnet, ERA white, nd ERA gry. Ech pprtus ws tested with 5 specimens per ttchment system. Pek lod-todislodgement ws mesured. Finlly, it ws stted tht retention force of superflex bll nd Loctor ws lmost the sme. This is in line with the results of the present study [15]. Boteg (Percicb university, Brzil) compred retention nd ftigue resistnce of four kinds of overdenture ttchments (two types of superflex bll nd two types of prefbricted br clip). 40 smples were divided into 4 groups, ech of 10. All the smples were put in rtificil sliv nd 5500 tension cycles with 0.8 Hz frequency. Then the Universl Testing Mchine ws used to evlute smples retention. Finlly, it ws climed tht retention force of prefbricted br clip nd superflex bll were equl. This is not similr to our study. This difference my rise from the type of br which ws prefbricted in Boteg study [16]. Sdig did study in which two model designs were selected bsed on the number nd loction of the inserted implnts: In the first setup, two implnts were plced in the cnine regions; in the second setup, two implnts were plced in the cnine regions nd two in the premolr regions. For ech model, three types of connectors were used: mgnets, blls, nd loctors. Then, 10 resin bses were fbricted nd three hooks were fixed t tripodl loctions for chin testing. The finding of the study reveled tht Loctor retention ws more thn bll. This is in disgreement with the findings of the present study, perhps due to the difference in retention force of different colors of cps, either loctors or superflex blls, nd due to the fct tht in both of them different colors of cps hve different retention forces [17]. Fu et l., compred retention force of three prefbricted nd two mchine milling ttchments. Three types of ERA mtrices, one prefbricted nd two cstble were used. There were 10 smples in ech group nd white nylon ptrices were trnsferred to denture bses. All smples were tested t the speed of 0.2 mm/min using n Instron mchine. ANOVA nd Student t-test were used to nlyze the dt. Retention forces of ll groups, fter the first tension cycle, were lmost equl. Apprently, it is in disgreement with the findings of the present study, lthough the difference between the two studies, nd in this regrd, is subtle nd not significnt [18]. Alsbeeh et l. compred retention forces of six different ttchments (four types of bll ttchment nd two types of loctor ttchment) in the lower rch. Two prototype bll ttchments of lrger dimensions (7.9 nd 5.9 mm) nd four blls nd stud ttchments with stndrd dimensions (2.25 nd 4.0 mm) were evluted on three identicl test csts. A Universl Testing Mchine ws used to exert verticl dislodging force t cross-hed speed of 50 mm/min to ech overdenture smple from the nterior direction. A totl of 300 pull tests were conducted (50 per ttchment system). The mximum retentive force to seprte ech overdenture from the supporting implnt ws mesured. They indicted tht loctors hd more retention force nd bll ttchments demonstrted less retention thn loctors. This is in greement with the results of our study [19]. References [1] Truhlr RS, Csino AJ, Cncro JJ. Tretment plnning 57

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