An in vitro comparative study to evaluate the retention of different attachment systems used in implant retained overdentures

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Originl Article An in vitro comprtive study to evlute the retention of different ttchment systems used in implnt retined overdentures Tejomy Shstry, N. M. Anupm, Shilp Shetty, M.

1 Originl Article An in vitro comprtive study to evlute the retention of different ttchment systems used in implnt retined overdentures Tejomy Shstry, N. M. Anupm, Shilp Shetty, M. Nlinkshmm Deprtment of Prosthodontics nd Crown nd Bridge, VS Dentl College nd Hospitl, Bengluru, Krntk, Indi Abstrct Aim: The im of this in vitro study ws to compre the chnge in the retentive force nd removl torque of three ttchment systems during simultion of insertion removl cycles. Methodology: Edentulous mndibulr models were mde with het cured polymethyl methcrylte resin. Two implnt replics (CMI), of 3.75 mm dimeter nd 10 mm length, were plced in the intrforminl region. Acrylic resin mndibulr overdentures were fbricted nd provision ws mde to receive three different overdenture ttchment systems, prefbricted bll/o ring ttchment (Lifecre Biosystems, Thne, Indi), Hder br nd clip ttchment (Sterngold, Attleboro, MA), nd Loctor implnt overdenture ttchment stud type (Zest Anchors LLC, USA). Using universl testing mchine, ech of the models were subjected to 100 pulls ech to dislodge the overdenture from the crylic model, nd the force vlues s indicted on the digitl indictor were tbulted both before nd fter thermocycling (AT). Sttisticl Anlysis Used: Sttisticl nlysis comprised Kolmogorov Smirnov test, Friedmn test, nd Wilcoxon signed rnks test. Results: The sttisticl model reveled significntly different behvior of the ttchment systems both before nd AT. The bll/o ring nd br ttchments developed higher retentive force s compred to the loctor ttchment. The br nd clip ttchment exhibited the highest pek s well s the highest men retention force t the end of the study. The Loctor ttchment showed decrese in retentive potentil fter n erly pek. Conclusions nd Clinicl Implictions: The bll/o ring nd br nd clip ttchments exhibit higher retentive cpcities thn the Loctor ttchment over time. Key Words: Dislodging cycles, Loctor, overdenture ttchment, retentive force, thermocycling Address for correspondence: Dr. Tejomy Shstry, Room No. 110, KIMS Men s Hostel, 18 th Cross, 24 th Min, Bnshnkri 2 nd Stge, Bengluru , Krntk, Indi. E mil: tejomy.shstry@gmil.com Received: 18 th June, 2015, Accepted: 11 th October, 2015 Access this rticle online Quick Response Code: Website: ips.org DOI: / This is n open ccess rticle distributed under the terms of the Cretive Commons Attribution NonCommercil ShreAlike 3.0 License, which llows others to remix, twek, nd build 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 How to cite this rticle: Shstry T, Anupm NM, Shetty S, Nlinkshmm M. An in vitro comprtive study to evlute the retention of different ttchment systems used in implnt-retined overdentures. J Indin Prosthodont Soc 2016;16: The Journl of Indin Prosthodontic Society Published by Wolters Kluwer - Medknow 159

2 INTRODUCTION The most common problem ssocited with the mngement of edentulous ptients is the severely resorbed mndibulr ridge, especilly in older ge when dptive cpcities re reduced. [1 5] This compromised sitution consequently results in the fbriction of unstisfctory dentures with poor retention nd stbility which cn further precipitte psychosocil problems. [6 9] The stbiliztion of the lower denture with two interforminl implnts hs provided relible nd predictble tretment outcomes. It is regrded s the minimum stndrd of cre for edentulous ptients. [10] The prognosis of the prosthesis depends on two importnt fctors: (1) Retention nd (2) stress distribution. Retention is the function of nd is directly relted to the ttchment system employed. The success of implnt retined overdentures primrily depends on the retentive cpcity of its ttchment element to sustin its long term functionlity. [11] The choice of the ttchment is dependent upon the retention required, jw morphology, ntomy, mucosl ridge, orl function, nd ptient complince for recll. [12] Bll ttchments nd br units for implnt overdentures hve evolved from the erly 1960 s. Bll ttchments were considered the simplest type of ttchments for clinicl ppliction with tooth or implnt supported overdentures. [13] However, it is lso well documented tht o rings grdully loose retention, nd must be replced periodiclly. On the other hnd, incresed technique sensitivity nd costs but with fvorble stbility hve been reported regrding the br ttchments. Other disdvntges of the br system include mucosl hyperplsi, hygiene problems, nd the necessity of the retention clip s ctivtion. [14 16] The Loctor ttchment (Zest Anchors Inc., Homepge, Escondido, CA, USA) which ws introduced in 2001, is new system, which does not use the splinting of implnts. This ttchment is self ligning nd hs dul retention in different colors with different retention vlues. [12,17,18] Loctor ttchments re vilble in different verticl heights, they re resilient, retentive, nd durble, nd hve some built in ngultion compenstion. In ddition, repir nd replcement re fst nd esy. There is lck of clinicl studies on the Loctor system. [19,20] Typiclly, the combintion of mterils in overdenture ttchments comprises metl metl or metl plstic/nylon contct which might show differences regrding surfce wer nd thus resistnce to repetitive removl nd insertion cycles. [21,22] In ddition to this, chnge in retentive cpcity of the ttchment systems is expected when the overdenture is subjected to period of service in the orl cvity under the influence of inherently present fluids nd ingested food nd liquids during mstiction nd insertion nd removl of the prosthesis. Micro nd mcro movement between the retentive surfces of n ttchment during mstiction nd removl of the overdenture will led to wer nd diminish retentive forces over time. [23] Thus, the im of this in vitro study ws to test the hypothesis tht the new unsplinted ttchment system experiences less chnge of retentive force fter repeted insertion removl cycles compred to cliniclly estblished splinted ttchment systems. Aim of the study The im of this study ws to ssess nd evlute the retentive cpcity of three most commonly employed ttchment systems in implnt retined overdentures. Objectives To mesure the retentive cpcity of different implnt overdenture ttchment systems To compre the retentive cpcity of these ttchment systems To compre the chnge in the retentive force of different ttchment systems during simultion of insertion removl cycles. Mterils nd equipment Edentulous mndibulr crylic resin models mde with het polymerized polymethyl methcrylte resin (DPI Het Cure, DPI, Mumbi, Mhrshtr, Indi) Two implnt replics (CMI) 3.75 mm dimeter, 10 mm length [Figure 1]. Acrylic resin mndibulr overdentures fbricted with het polymerized polymethyl methcrylte resin (DPI Het Cure, DPI, Mumbi, Mhrshtr, Indi). Acrylic denture teeth (Acryl Rock) Prefbricted bll/o ring ttchment (Lifecre Biosystems, Thne, Indi) Hder br nd clip ttchment (Sterngold, Attleboro, MA) Loctor implnt overdenture ttchment stud type (Zest Anchors LLC, USA) Resin cement (Relyx, 3M ESPE) Universl testing mchine (UTM) Instron 5567 compression tension tensile meter 160 The Journl of Indin Prosthodontic Society Apr-Jun 2016 Vol 16 Issue 2

(c) Mndibulr overdenture fbricted in conventionl mnner using het polymerized polymethyl methcrylte resin Mnul thermocycling unit two S U Polytub, Schuler Dentl, Germny Surveyor tble nd metllic clips.

3 b c b Figure 1: () Two implnt replics (CMI) 3.75 mm dimeter, 10 mm length. (b) Edentulous mndibulr crylic resin model with the two implnt replics plced in the intrforminl region (22 mm prt) nd retined with resin cement. (c) Mndibulr overdenture fbricted in conventionl mnner using het polymerized polymethyl methcrylte resin Mnul thermocycling unit two S U Polytub, Schuler Dentl, Germny Surveyor tble nd metllic clips. METHODOLOGY Fbriction of study models Edentulous mndibulr models were mde from het polymerized polymethyl methcrylte resin (DPI Het Cure, DPI, Mumbi, Mhrshtr, Indi) [Figure 1b]. Mndibulr Overdentures were fbricted in conventionl mnner using het polymerized polymethyl methcrylte resin (DPI Het Cure, DPI, Mumbi, Mhrshtr, Indi) [Figure 1c]. Three overdenture models were prepred nd five denture smples were prepred for ech group. Bll/o ring ttchment Br nd clip ttchment Loctor ttchment. The implnt nlogs (CMI 3.75 mm 10 mm) were plced in the crylic models using physiodispenser, simulting the conventionl plcement of implnt in osteotomy site in the mndible nd subsequently secured with resin cement (Relyx, 3M ESPE, USA) [Figure 1b]. IMPLANT OVERDENTURE ATTACHMENT SYSTEMS Prefbricted bll/o ring ttchment (Lifecre Biosystems, Thne, Indi) [Figure 2] c Figure 2: () Prefbricted bll/o ring ttchment. (b) Br ttchment. (c) Loctor ttchment with vrious components A metllic housing with rubber o ring component ws used for the bll nd ring ttchment. Hder br nd clip ttchment [Figure 2b] A cstble Hder br of length = 22 mm; dimeter = 1.8 mm = 13 guge. Nylon rider length = 5 mm; width = 2.6 mm moderte retention Loctor ttchment (Zest Anchors LLC, USA) [Figure 2c] Tissue cuff length = 1.0 mm; dimeter = 3.86 mm Loctor mle blue inserts retention force = 1.5 lbs (6.7 N) Mximum convergence = 20. Ech ttchment system ws secured into the implnt replics on the crylic resin model nd the overdentures with the corresponding housing were subsequently plced on it nd tightened to 35 Ncm [Figure 3 f]. Experimentl setup Acrylic overdentures with respective ttchment systems were plced on the crylic edentulous mndibulr models. Metllic clips were ttched to the dentures nd secured with cler utopolymerized crylic resin (DPI Cold Cure, Cler, DPI, Mumbi, Mhrshtr, Indi). The edentulous crylic model ws secured in plce using surveyor tble [Figure 4]. Retention force testing before thermocycling With the UTM (Instron 5567 compression tension tensile meter), ech of the models were subjected to 100 pulls ech to dislodge the overdenture from the crylic model, nd the force vlues s indicted on the digitl indictor were tbulted [Figures 5 nd 6]. The dislodging force ws pplied in verticl direction in the center of the crylic block joining the two metllic clmps holding the overdenture with the UTM The Journl of Indin Prosthodontic Society Apr-Jun 2016 Vol 16 Issue 2 161

d b e c Figure 3: ( c) Bll ttchment, br ttchment, nd Loctor ttchment secured on to the implnt replic on the crylic resin model.

overdenture with clips ttched secured in plce using surveyor tble Figure 6: Digitl vlues s seen on the universl testing mchine Figure 5: Universl testing mchine Instron 5567 compression tension

Thermocycling All the overdentures with the ttchments plced on the edentulous models were subjected to mnul thermocycling using S U Polytubs; one mintined t 5 ± 1 nd other t 55 ± 1 [Figure 7].

equivlent to 6 months of service in the orl cvity. [24] None of the smples filed.

4 d b e c Figure 3: ( c) Bll ttchment, br ttchment, nd Loctor ttchment secured on to the implnt replic on the crylic resin model. (d f) Acrylic resin overdenture with the o ring housing for bll ttchment, nylon ryder for the br ttchment, nd the Loctor mle blue insert f Figure 4: Edentulous mndibulr crylic resin model nd overdenture with clips ttched secured in plce using surveyor tble Figure 6: Digitl vlues s seen on the universl testing mchine Figure 5: Universl testing mchine Instron 5567 compression tension tensile meter used to dislodge the overdentures from the models operting t crosshed speed of 2 mm/30 ms. The redings were tken from the strt of the test. Thermocycling All the overdentures with the ttchments plced on the edentulous models were subjected to mnul thermocycling using S U Polytubs; one mintined t 5 ± 1 nd other t 55 ± 1 [Figure 7]. The test smples were subjected to totl of 5000 cycles with ech cycle equivlent to 30 s of dwell time in ech temperture controlled tub with trnsfer time of 10 s, with 5000 therml cycles being equivlent to 6 months of service in the orl cvity. [24] None of the smples filed. Retention force testing fter thermocycling Ech of the models ws gin subjected to 100 pulls ech to dislodge the overdenture from the crylic model nd the force vlues s indicted on the digitl indictor were tbulted. RESULTS The Kolmogorov Smirnov tests for normlity reveled no norml distribution (P < 0.05) for the dt; thus, norml distribution ws not ssumed. Comprison of the repeted mesures ws performed using Friedmn s test showing sttisticlly significnt decrese in concentrtion. In, χ 2 (1) =30.556, P < Post hoc nlysis with Wilcoxon signed rnk test ws conducted with Bonferroni correction pplied, resulting in significnce level set t P < The men concentrtion (± stndrd devition [SD]) ws (9.77) t bseline, (5.08) t fter thermocycling (AT). A significnt decrese ws seen 162 The Journl of Indin Prosthodontic Society Apr-Jun 2016 Vol 16 Issue 2

between AT nd bseline (Z = 5.969, P < 0.001) fter the completion of 5000 therml cycles [Tbles 1 5]. seen between AT nd bseline (Z = 4.446, P < 0.001) [Tbles 1 5]. In, χ 2 (1) =45.343, P < 0.001. Post hoc nlysis with Wilcoxon signed rnk test ws conducted with Bonferroni correction pplied, resulting in significnce level set t P < 0.

5 between AT nd bseline (Z = 5.969, P < 0.001) fter the completion of 5000 therml cycles [Tbles 1 5]. seen between AT nd bseline (Z = 4.446, P < 0.001) [Tbles 1 5]. In, χ 2 (1) =45.343, P < Post hoc nlysis with Wilcoxon signed rnk test ws conducted with Bonferroni correction pplied, resulting in significnce level set t P < The men concentrtion (±SD) ws (12.09) t bseline, (10.89) t AT. A significnt decrese ws seen between AT nd bseline (Z = 7.728, P < 0.001) [Tbles 1 5]. Interprettion The br nd clip ttchment showed the highest men retentive force of N nd N before nd AT, respectively. The mximum retentive force ws exhibited by the br nd In, χ 2 (1) =17.640, P < Post hoc nlysis with Wilcoxon signed rnk test ws conducted with Bonferroni correction pplied, resulting in significnce level set t P < The men concentrtion (±SD) ws (6.53) t bseline, (9.32) t AT. A significnt decrese ws Tble 1: Friedmn test descriptive sttistics Group n Men (SD) BT (9.77) AT (5.08) BT (12.09) AT (10.89) BT (6.53) AT (9.32) SD: Stndrd devition, BT: Before thermocycling, AT: After thermocycling Tble 2: Friedmn test men rnk Group Men rnk BT 1.78 AT 1.23 BT 1.84 AT 1.17 BT 1.71 AT 1.29 BT: Before thermocycling, AT: After thermocycling Tble 3: Friedmn test sttistics Group n 100 Chi squre df 1 Asymptotic significnce n 100 Chi squre df 1 Asymptotic significnce n 100 Chi squre df 1 Asymptotic significnce Figure 7: Mnul thermocycling unit S U Polytub, Schuler Dentl, Germny Tble 4: Wilcoxon signed rnks test rnks Group n Men rnk Sum of rnks AT BT Negtive rnks Positive rnks 22 b Ties 1 c Totl 100 AT BT Negtive rnks Positive rnks 16 b Ties 1 c Totl 100 AT BT Negtive rnks Positive rnks 29 b Ties 0 c Totl 100 AT < BT, b AT > BT, c AT=BT. BT: Before thermocycling, AT: After thermocycling Tble 5: Wilcoxon test sttistics Group AT BT Z Asymptotic significnce (two tiled) Z Asymptotic significnce (two tiled) Z Asymptotic significnce (two tiled) Bsed on positive rnks. BT: Before thermocycling, AT: After thermocycling The Journl of Indin Prosthodontic Society Apr-Jun 2016 Vol 16 Issue 2 163

6 clip ttchment, 82.3 N (cycle no. 56); followed by Loctor ttchment, 66.7 N (cycle no. 41); nd bll/o ring ttchment, 65.4 N (cycle no. 13). A decrese in the retention force ws observed in ll the three ttchment systems fter subjecting them to therml cycles nd this decrese ws found to be sttisticlly significnt (P < 0.05). The results obtined re summrized in Tble 6. DISCUSSION The underlying principle in employing retentive implnt overdenture systems for the tretment of edentulous ptients is to increse denture retention nd stbility, thereby promoting chewing function s well s ptient comfort nd complince. [25,26] Stud type, bll, nd conventionl br ttchments re the commonly used nchorge systems in implnt supported overdentures nd their efficcy is scientificlly supported. [27 30] Hence, these ttchment systems were chosen for this study. Splinted conventionl br ttchments hve demonstrted superior retentive cpcities over unsplinted systems. However, they hve few disdvntges; they re initilly more expensive, difficult to repir, nd mintining orl hygiene seems difficult, especilly for frgile elderly individuls. [27] overdentures. The experimentl set up, however, my hve hd few limittions. The smple size of the specimen used ws reltively smll, but ws in ccordnce with previous similr experiments. [30] It hs to be kept in mind tht for the current in vitro experiment, only mono directionl forces were pplied, which does not represent relistic model for clinicl sitution with overdentures. There, the min forces re generted in the region of the first molrs which will led to rottionl forces on the ttchments through leverge. [31-33] During the course of the study, the different ttchments showed complex evolution with peks s well s incresing nd/or decresing men retentive forces. The sttisticl model reveled significntly different behvior of the ttchment systems both before nd AT [Figures 8 nd 9]. The bll/o ring nd br ttchments developed higher retentive force s compred to the Loctor ttchments. The br nd clip ttchment exhibited the highest pek s well s the highest men retention force t the end of the study [Tble 6]. The Loctor ttchment showed decrese in retentive potentil fter n erly pek. In comprison with the br ttchments, bll nchors were preferred by clinicins becuse they were less technique sensitive, cost effective, esy to use nd to repir. [13] Stud type ttchments such s the Loctor were introduced s concept to simplify restortive procedures in implnt supported overdentures. This system is reltively esy in fbriction nd demonstrted cliniclly superior results when compred with bll nd br ttchments reltive to prosthodontic complictions nd hygiene. [29] This study ws performed under controlled experimentl simultion to evlute the retentive forces of three different types of nchorge systems used for implnt supported Figure 8: Progression of men retentive forces of the three ttchment systems (ech group n = 10) before thermocycling Tble 6: Summry of sttisticl nlysis Prmeter Bll/o ring ttchment Br nd clip ttchment Loctor ttchment Men±SD BT AT Initil men retentive force 40.3±15.83 N 46.9±13.9 N 33.5±9.77 N Minimum retentive force 20.6 N 39.5 N 33.1 N Mximum retentive force 65.4 N (cycle number 13) 82.3 N (cycle number 56) 66.7 N (cycle number 41) Chnge in retentive force fter thermocycling Decreses Decreses Decreses P <0.001 sttisticlly significnt <0.001 sttisticlly significnt <0.001 sttisticlly significnt SD: Stndrd devition, BT: Before thermocycling, AT: After thermocycling 164 The Journl of Indin Prosthodontic Society Apr-Jun 2016 Vol 16 Issue 2

7 Figure 9: Progression of men retentive forces of the three ttchment systems (ech group n = 10) fter thermocycling CONCLUSION The bll/o ring nd br clip ttchments mintin their retentive cpcity longer thn the Loctor ttchment. A decrese in the retention force ws observed in ll the three ttchment systems fter subjecting them to therml cycles nd this decrese ws found to be sttisticlly significnt. Further reserch is required to understnd the loss in retention force of vrious overdenture ttchment systems. Finncil support nd sponsorship Nil. Conflicts of interest There re no conflicts of interest. REFERENCES 1. Mericske Stern RD, Tylor TD, Belser U. Mngement of the edentulous ptient. Clin Orl Implnts Res 2000;11 Suppl 1: Müller F, Heth R, Ott R. Mximum bite force fter the replcement of complete dentures. Gerodontology 2001;18: Müller F, Nhrro M, Crlsson GE. Wht re the prevlence nd incidence of tooth loss in the dult nd elderly popultion in Europe? 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8 et l. Effects of in vitro cyclic dislodging on retentive force nd removl torque of three overdenture ttchment systems. Clin Orl Implnts Res 2014;25: Steiner M, Ludwig K, Kern M. Retention forces of new implnt supported br ttchment system. Clin Orl Implnts Res 2009;20: Wiskott H. Bioengineering pplied to orl implntology. Biomechnicl studies. In: Bllo A, editor. Implnt Dentistry Reserch Guide: Bsic, Trnsltionl nd Clinicl Reserch. 1 st ed. Huppuge, NY, USA: Nov Science Publishers; p Yng TC, Med Y, Gond T, Kotech S. Attchment systems for implnt overdenture: Influence of implnt inclintion on retentive nd lterl forces. Clin Orl Implnts Res 2011;22: New fetures on the journl s website Optimized content for mobile nd hnd-held devices HTML pges hve been optimized of mobile nd other hnd-held devices (such s ipd, Kindle, ipod) for fster browsing speed. Click on [Mobile Full text] from Tble of Contents pge. This is simple HTML version for fster downlod on mobiles (if viewed on desktop, it will be utomticlly redirected to full HTML version) E-Pub for hnd-held devices EPUB is n open e-book stndrd recommended by The Interntionl Digitl Publishing Forum which is designed for reflowble content i.e. the text disply cn be optimized for prticulr disply device. Click on [EPub] from Tble of Contents pge. There re vrious e-pub reders such s for Windows: Digitl Editions, OS X: Clibre/Bookworm, iphone/ipod Touch/iPd: Stnz, nd Linux: Clibre/Bookworm. E-Book for desktop One cn lso see the entire issue s printed here in flip book version on desktops. Links re vilble from Current Issue s well s Archives pges. Click on View s ebook 166 The Journl of Indin Prosthodontic Society Apr-Jun 2016 Vol 16 Issue 2

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

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