The advent of computer-aided design/computerassisted

Transcription

1 Comprison of Customized Autments Mde from Titnium nd Mchinle Precious Alloy Jee-Ho Lee, DDS, PhD 1 /Ji-Mn Prk, DDS, PhD 2 /Eun-Jin Prk, DDS, PhD 3 / Ji-Young Kok, DDS, PhD 4 /Seong-Kyun Kim, DDS, PhD 4 /Seong-Joo Heo, DDS, PhD 4 Purpose: To investigte the clinicl usefulness, customized utment produced with the Pd-Ag-In lloy ws compred with customized utment produced with the conventionl titnium lloy for discolortion nd mechnicl ccurcy. Mterils nd Methods: Discolortion nd resistnce to corrosion of the Pd-Ag-In lloy were evluted using chemicl solutions. Mrginl dpttion of internl-type implnts nd utments ws compred using 10 titnium utments nd 10 Pd-Ag-In utments using surfce mesuring system. A detorque test ws performed on 12 implnt-utment complexes of ech control nd experimentl group to investigte screw joint stility. Cyclic loding simulting humn s mstiction movement for 1 yer ws pplied fter 30 Ncm initil tightening, nd the removl torque ws mesured using digitl torque guge. The noninferiority test ws conducted to compre the Pd-Ag-In lloy with titnium utment with 10% mrgin. Results: The Pd-Ag-In lloy hd wrm yellow color nd displyed stle resistnce to discolortion nd corrosion, resulting in n dvntgeous esthetic property. When compred to the titnium lloy, it did not show noninferiority with respect to the gp etween the implnt nd the utment; the gp ws pproximtely 13.3 µm on verge, which ws not significntly different from those oserved in previous studies. After long-term use, it displyed sttisticlly significnt noninferiority in the removl torque vlue compred to the titnium group. Conclusion: The Pd-Ag-In lloy sed customized utment hd good mechnicl properties of the implnt-utment complex s well s superior esthetic property, nd cn provide fvorle outcomes in nterior implnt restortion. Int J Orl Mxillofc Implnts 2016;31: doi: /jomi.4102 Keywords: customized utment, cyclic loding, dentl implnts, detorque vlue, implnt-utment gp The dvent of computer-ided design/computerssisted mnufcture (CAD/CAM) technology in dentistry hs enled the ccurte friction of customized dentl prostheses in short time. Since the 1970s, CAD/CAM technology hs replced the trditionl methods of processing dentl prostheses nd expnded its ppliction 1 3 from the friction of fixed dentl prostheses, including fixed prtil dentures nd crowns, to clss II inlys 4 7 nd the design of 1 Assistnt Professor, Deprtment of Orl & Mxillofcil Surgery, Seoul Asn Medicl Center, Seoul, Kore. 2 Clinicl Associte Professor, Deprtment of Prosthodontics & Dentl Reserch Institute, Seoul Ntionl University Gwnk Dentl Hospitl, Seoul, Kore. 3 Professor, Deprtment of Prosthodontics, Ewh Womns University, Seoul, Kore. 4 Professor, Deprtment of Prosthodontics & Dentl Reserch Institute, Seoul Ntionl University, Seoul, Kore. Correspondence to: Dr Ji-Mn Prk, Deprtment of Prosthodontics nd Dentl Reserch Institute, School of Dentistry, Seoul Ntionl University Gwnk Dentl Hospitl, 1 Gwnk-ro, Gwnk-gu, Seoul, , South Kore. Fx: Emil: jimrn@snu.c.kr 2016 y Quintessence Pulishing Co Inc. removle prtil dentures nd complete dentures, 8 10 s well s implnt prostheses nd surgicl guides CAD/CAM systems cn decrese deformtion, in prticulr, those cused y the trditionl lost wx technique, nd imprt regulr mteril properties. The shpe nd thickness of the prostheses cn lso e controlled s needed with CAD/CAM system. The system, therefore, cn sve processing time in dentl lortory compred to the time involved in trditionl method for the friction of dentl prostheses. 15,16 Antomicl morphology nd ngultion re ville for correction in CAD/CAM titnium-customized utments s in cst utments. 17 The min mterils used for customized utments mde y CAD/CAM system hve een titnium or zirconi. The mteril property of titnium utment is the sme s tht of titnium dentl implnt. Therefore, titnium utment hs less rsion nd high resistnce to frcture in long-term use. However, thin gingiv cuses esthetic prolems such s shdow effect in the cse of nterior teeth. While zirconi utments re frequently selected for ptients with thin gingiv for the esthetic purpose, they hve disdvntge; they cuse rsion of the implnt itself owing to the wer resistnce difference etween zirconi nd 92 Volume 31, Numer 1, 2016

2 titnium, especilly for externl-type connection implnts. 18,19 Zirconi utments lso cn e frctured t the thin connecting prt in internl-type implnts Hyrid-type utments using titnium linker my fil t the ond etween the linker nd the superior prt of zirconi. 23,24 Although titnium hs een widely used in the CAD/CAM system s processing metl, 25,26 it forms thick oxidtion lyer on the surfce nd requires reltively long times for processing. 27 A plldium lloy cn overcome these shortcomings, nd color similr to the gold lloy cn e otined y djusting the rtio of plldium to indium. It lso improves the mteril properties nd the ond strength etween the lloy nd cermic. Hence, the plldium lloy hs recently een considered s n lterntive to replce titnium in dentl implnt prostheses A lrge numer of mechnicl complictions in long-term follow-up for implnt prostheses come from the compromised fixtion nd stility of the connection prt etween the implnt nd the utment Screw loosening is one of the frequent prolems, especilly for the externl utt joint implnts. 34 Screw joint stility generlly depends on the goodness of fit of the connection of the implnt-utment nd the tolernce etween them, nd screw loosening occurs when the ending force is lrger thn the clmping force cused y the prelod of the screw nd the settling effect etween the screw nd the internl surfce of the implnt. For internl-connection implnts, the frictionl resistnce t the implnt-utment interfce my hve greter influence on the implnt screw joint stility thn the prelod of screw. With the wedge effect nd friction resistnce, the overll joint cn still e stle while the detorque vlue of the internl-connection implnt decreses fter the xil displcement of the utment. 35 The stility of the implnt superstructure is evluted y mesuring the screw joint stility nd screw loosening. The most universl method is to investigte micromotion fter pplying dynmic loding using strin guge or mesuring the detorque of the utment screw using digitl torque guge When the ssessment of stility in the implnt superstructure using gp mesurement etween the implnts nd utments nd nlyzing the fit of the implnt superstructure is required, severl methods re ville, for exmple, the mesurement of the gp in the outer perimeter of the implnt-utment connection nd the dpttion s function of rdius. 39,40 Verifiction of the mechnicl properties of the Pd- Ag-In lloy is needed for their use s lloy utments in dentl implnt prostheses to overcome the esthetic nd mechnicl limits of the trditionl titnium utment, therey improving clinicl outcomes. However, there hs een little reserch on the mrginl dpttion nd detorque vlue etween the implnts nd the customized utments mde y the CAD/CAM-sed Pd-Ag-In lloy. The purpose of this study is to compre mechnicl ccurcy nd esthetics of the CAD/CAMsed customized utment for the ppliction of implnt prostheses to the trditionl titnium customized utment, nd evlute the prospective clinicl ppliction. MATERIALS AND METHODS Properties of Code 10.2 Alloy In this study, the code 10.2 lloy (Cergem Biosys) ws composed of plldium (Pd, 30~40 wt %), indium (In, 30~40 wt %), silver (Ag, 20~30 wt %), gold (Au, 1~5 wt %), nd copper (Cu, 2~10 wt %). The sic lloy ws mde using vcuum-melting furnce (DTIH- 0050VMF, Dongyng Induction Melting Furnce) for preventing ir impregntion. The corrosion nd discolortion ehvior were exmined ccording to ISO22674:2006. Experimentl specimens tht were prepred to investigte the resistnce to corrosion hd size of mm. A corrosion solution of ph 2.3 ± 0.1 (lctic cid + sodium chloride, CAS CAS ) ws mde nd contined 1 ml/cm 2 of specimen in glss vessels t 37 C for 7 dys. The solution ws nlyzed using ph meter (720A, Orion Reserch) fter removl of the specimen. Specimens with 10 mm rdius nd 0.5 mm thickness were used for testing resistnce to discolortion y immersing in 0.1 mol/l solution of sodium sulfide for 15 s/min using the discolortion tester (Trnish tester, Myungsung Industry) for 72 hours. The specimens were wshed fter the immersing process nd were visully compred with smples tht were not immersed. Customized Autment Friction For the control group, premilled lock (Biogenesis) ws prepred from titnium lloy (Ti 6Al-4V ELI) for the customized utment. For the experimentl group, the mold ws designed to mke rod-type lloy for premilled lock of Code 10.2 lloy, which ws fixed t the milling mchine (SR-20RIII, Str Micronics) for the friction of the customized utment. The customized utment ws designed ccording to the molr lirry, nd the cutck procedure ws performed using dentl CAD/CAM system (Dentl System, 3Shpe). Premilled locks of titnium (control group) nd Code 10.2 lloy (experimentl group) were processed using 5-xis milling mchine (Arum DEG-5X100, Doowon) for the customized utments The Interntionl Journl of Orl & Mxillofcil Implnts 93

3 Fig 1 (left) Friction of customized utments. () Processing of premilled lock using 5-xis milling mchine; () completed customized utments. Fig 2 (elow) Gp mesurement etween the customized utment nd implnt. () Accur 2000 surfce mesuring system; () implnt-utment complex; (c) gp mesurement procedure. c of the sme design (Fig 1). In this study, n internlconnection-type, regulr-dimeter implnt system (GSIII, Osstem) ws used for connection to the customized utments. Gp Mesurement Between the Customized Autment nd Implnt Twenty internl-type implnts were prepred for the comprison of mrginl dpttion etween the titnium utment nd the Code 10.2 lloy utment. Ten implnt-utment complexes were prepred for the control (titnium) nd nother 10 for the experimentl (Code 10.2 lloy) group. The gp ws mesured using surfce mesuring system (Accur 2000, Intec Plus) with 0.1 mm precision t 240 mgnifiction. The mesurement ws repeted 50 times for ech specimen (Fig 2). Screw Joint Stility Evlution y Detorque Vlue Mesurement After Cyclic Loding Twelve implnt-utment complexes were prepred for the control group nd experimentl group ech. The custom-mde crowns were fricted for the lod cell of universl testing mchine to evenly distriute the force on the specimens. A jig ws mde for the fixtion of the implnt-utment specimen conforming to the ISO 14801:2007 stndrd, nd the lod cell ws set for the loding to e pplied t 30 degrees. The implntutment smples were tightened to 30 Ncm while they were held in holding device specilly designed for the torque mesurement. Torque vlues were mesured using digitl torque guge (MTT03-50, MARK-10) ccording to mnufcturer recommendtions. The torque guge ws lso fixed in the holding device to prevent it from off-xis movement during mesurement (Fig 3). The initil detorque vlue ws mesured 10 minutes fter tightening. Before pplying 10 6 cycles of loding, the 30 Ncm tightening ws repeted two times t 10-minute intervls. The finl detorque vlue ws mesured fter cyclic loding (Fig 4). A universl testing mchine (ElectroPlusTM E3000, Instron) ws used for the repeted loding for 10 6 cycles rnging from 0 to 320 N with sine wve of 14 Hz, which corresponded to humn s mstiction movement for 1 yer. 94 Volume 31, Numer 1, 2016

4 Fig 3 Detorque mesurement nd cyclic loding procedure. () Digitl torque guge ws used for torque control nd mesurement. () Custom-mde housing prevented the torque guge from exerting n off-xis force on the screw. (c) Universl testing mchine ws utilized to pply repeted loding tht is equivlent to 1 yer of mstiction. c Sttisticl Anlysis The sttisticl nlyses were performed with R softwre version 3.0 (R Foundtion for Sttisticl Computing). The noninferiority test for the gp mesurements ws conducted for the titnium nd the Code 10.2 lloy with noninferiority mrgin (NIM) of 10% of the control group. If the upper ound of the 95% confidence intervl (CI) for the difference of the chnges (Code 10.2 lloy chnges-titnium chnges) ws smller thn the noninferiority mrgin, the uthors declred the smple noninferior. The men implnt-utment gps were compred etween the titnium nd the Code 10.2 lloy using the Mnn-Whitney test. For the removl torque test, the noninferiority test to compre the chnge etween the initil vlues nd the mesurement fter the cycles for the two groups ws conducted, nd 10% noninferiority mrgin ws considered. Men detorque vlues of the titnium nd the Code 10.2 lloy groups were compred efore nd fter cyclic loding, respectively, using the Mnn-Whitney test t significnce level of α =.05. RESULTS In resistnce to corrosion test of the Code 10.2 lloy, the men mount of ions mesured in the solution ws mg/cm 2, nd gold nd plldium were not detected. However, In ws detected t 78.4 mg/cm 2, nd Ag ws detected t 0.31 mg/cm 2. The mximum metl ion relese did not exceed 200 µg/cm 2 fter 7 dys, which ws the llowed limit specified in ISO22674:2006. All of the specimens hd no discolortion in the test of resistnce to discolortion. A CI of 95% for the difference of the verge implnt-utment gp rnging from -4.1 to 2.0 µm nd the mximum (2.0 µm) ws lrger thn the NIM, which ws 1.2 µm ccording to the 10% setting from the control group. Therefore, noninferiority ws not shown in the comprison of the gp etween titnium nd Code 10.2 lloy utments (Fig 5). The men gp ws 12.2 ± 2.0 µm in titnium nd 13.3 ± 3.7 µm in the Code 10.2 lloy. A significnt difference ws not shown in the mrginl gp etween the two groups (P =.76) (Fig 5). For the removl torque test, CI of 95% for the difference of chnge rnging from -7.0 to -2.1 Ncm nd the mximum (-2.1 Ncm) ws smller thn the NIM, which ws 1.5 Ncm ccording to the 10% setting from the control group. Therefore, noninferiority ws shown in the comprison of the detorque vlue (Fig 6, Tle 1). The men difference efore nd fter the cycles ws 14.7 ± 3.1 Ncm in titnium nd 10.1 ± 2.6 Ncm in the Code 10.2 lloy. A significnt difference ws shown in the comprison of the difference of chnge in detorque vlue fter loding (P <.01). The men initil torque ws 24.3 ± 2.6 Ncm in titnium nd 22.8 ± 2.1 Ncm in the Code 10.2 lloy. The men torque fter cyclic loding ws 9.7 Ncm in titnium nd 12.7 Ncm in the Code 10.2 lloy (Tle 1). A significnt difference ws not shown in the initil torque etween the two groups (P =.13), ut ws seen in the torque fter loding (P <.01) (Fig 6). The Interntionl Journl of Orl & Mxillofcil Implnts 95

5 10 min 10 min 10 min Loding 10 6 cycles 30 Ncm tightening 30 Ncm tightening Initil removl torque 30 Ncm tightening 30 Ncm tightening Removl torque fter loding Fig 4 Experiment protocol. Customized utment ws tightened twice with 30 Ncm torque t 10-minute intervls. The initil detorque ws mesured 10 minutes fter the second tightening. The procedure ws repeted efore pplying 10 6 cycles of loding simulting the mstiction movement for 1 yer. The finl detorque ws mesured fter cyclic loding Two-sided 95% CI of implntutment microgp (µm) Implnt-utment microgp (µm) Gp difference (Code 10.2 Ti-6Al-4V) 0 Code 10.2 Ti-6Al-4V Fig 5 Gp mesurement of the customized utment nd implnt. () Noninferiority could not e confirmed in the comprison under the confidence intervl of 95% for the difference of verge. The green line denotes the noninferiority mrgin. () Men microgp vlue of Code 10.2 nd Ti-6Al-4V lloy groups. Two-sided 95% CI of detorque vlue chnge fter loding (Ncm) Detorque vlue chnge difference (Code 10.2 Ti-6Al-4V) Detorque vlue efore nd fter cyclic loding (Ncm) Initil Code 10.2 Ti-6Al-4V * After loding Fig 6 Comprison of removl torque fter cyclic loding. () Noninferiority in the detorque vlue ws found t 95% confidence intervl of detorque vlue chnge etween Code 10.2 lloy nd Ti-6Al-4V lloy. The green line refers to the noninferiority mrgin. () Men detorque vlues efore nd fter 10 6 cycles of loding. The sterisk denotes significnt difference (P <.01). 96 Volume 31, Numer 1, 2016

6 DISCUSSION With the recent dvnce of CAD/CAM technology, the use of customized utments for the purpose of overcoming the shpe limittions of the conventionl stock utments nd reducing the cost of mterils for implnt-supported prostheses in the field of implnts hs incresed grdully. However, the use of customized utments mde of titnium is limited for nterior esthetics ecuse when the gingiv is thin, the titnium mteril underneth the gingiv is visile externlly or the gingiv looks gry nd dim. In color study on pig gingive, Jung et l reported tht the titnium underneth the crown ws visile through the gingiv if the thickness of the gingiv ws less thn 2 mm. 41 Ishikw-Ngi et l conducted spectroscopic color mesurements of the gingiv round the implnt, where eight color strips (white, lck, light pink, pink, light ornge, ornge, gold, nd violet) were plced, nd showed tht light pink displyed cliniclly indistinguishle color difference from the color of the implnt neck. To ddress the prolem tht the color of the metl is visile through tissues round the implnt, the surfce of the implnt neck or utments is treted with n nodizing tretment to give yellow color, nd thus, the esthetic limittions of titnium-sed mteril re improved. 42 Titnium utments coted with titnium nitride (TiN) using the cthodic rc deposition technique hve een utilized to msk gryish tint through the gingiv. Mezger nd Creugers mentioned tht TiN coting displyed outstnding chrcteristics such s rsion nd corrosion resistnce, ut since defects on the surfce of the coting such s pores nd microcrcks were oserved, the development of homogeneous nd continuous coting films ws necessry. 43 Since such coting technology does not ddress the prolem of the metl color directly nd it is tretment limited to the surfce, there hs een n issue of peeling of the coting. 44 The Code 10.2 lloy hd wrm yellow color, which ws the color of the lloy itself, nd it did not show the prolem of exfolition during the study. The corrosion nd discolortion resistnce test ws done to evlute the lloy s esthetic spect ecuse the corroded or discolored utment might influence the nterior esthetics y showing the gryish gingivl hue or the exposed utment itself round the recessed gingiv. All of the specimens hd no discolortion, nd ions of precious metl were not detected in corrosion solution. In the present study, the noninferiority test ws chosen to compre titnium nd Code 10.2 lloy for the microgp nd the removl torque chnge fter cyclic loding. There my e significntly lrger microgp in the Code 10.2 lloy compred to titnium, nd the Tle 1 Detorque Vlue Before nd After the 10 6 Cycles of Functionl Loding Control, Titnium (n = 12) Experimentl, Code 10.2 (n = 12) P vlue Initil 24.3 ± ± After 10 6 cycles 9.7 ± ± 1.5 <.01 Difference 14.7 ± ± 2.6 <.01 Detorque vlues were compred using Mnn-Whitney test t significnce level of α =.05. detorque vlue chnge in the Code 10.2 lloy might e lrger thn tht of titnium in the men comprison. However, if noninferiority is shown in the Code 10.2 lloy, it cn e considered to t lest not e inferior to currently used titnium nd cliniclly cceptle in return for the given secondry enefits. 45 In order to exmine how precisely the utment screw joint ws fricted, the gp in the outer dimeter of the implnt-utment ssemly ws mesured fter friction. A totl of 50 points were selected round the outer perimeter of the implnt-utment connection, sed on report y Groten et l. 46 Becuse the morphologic vritions of implnt components re smll, the numer 50 ws considered to e sufficient to estimte the men discrepncy of the implnt-utment gp. The noninferiority of the Code 10.2 lloy to titnium ws not shown for the gp etween the implnt nd the utment in 10% noninferiority mrgin. However, in the men comprison, the gps of two groups were not significntly different, which were 12.2 ± 2.0 µm in titnium nd 13.3 ± 3.7 µm in the Code 10.2 lloy. The verge microgp of the Code 10.2 lloy ws shown to e different from tht of titnium lloys y 1.1 µm, which is cliniclly considered not very different. There hve een vrious reports on the gp size in the implntutment interfce depending on the method of mesurement. Clln et l reported gp size of 30 to 135 µm, 47 while Jnsen et l 48 reported etween 1 nd 10 µm. The gp size mesured in this study ws not significntly different from previous studies. According to Pssos et l, 49 even when the gp ws less thn 5 µm, the invsion of E coli, with dimeter of 1.1 to 1.5 µm nd length of 2 to 6 µm, occurred in mny implnt systems, while n implnt with hexgonl, tpered internl connection hd etter cpcity to sel. 50,51 Since it is difficult to stop the E coli invsion in most of the implnt systems, crestl one loss in sucer shpe is in fct found round the implnt-utment gp in the implnts of the externl connection type. 52 The microgp is positioned fr from the crestl one in cse of internl-connection-type implnts with verticl offset like the soft tissue level Strumnn implnt The Interntionl Journl of Orl & Mxillofcil Implnts 97

7 or those with horizontl offset tht were selected in this study. It hs een reported tht these implnt systems showed less one resorption round implnts compred to utt-joint externl connection types It is considered tht more studies on precision re needed in order to improve the mechnicl complince, nd dditionl iologic studies on the cteril invsion re lso necessry. In order to investigte the stility ginst screw loosening, which is one of the frequent implnt complictions fter long-term use, the detorque vlue ws mesured efore nd fter cyclic loding of 1 million cycles corresponding to humn mstictory cycles for yer. In this study, following the initil 30-Ncm tightening torque, retightening ws done fter 10 minutes. Simos et l 56 reported tht repeted tightening protocol prevented settling effect, which induces loss of prelod in the initil stge in cse of twopiece utments. Becuse customized utment nd screw, which were used in oth groups, cn e ssumed to e nother form of two-piece utment, repeted tightening ws pplied. 57 Detorque vlues fter cyclic loding for ll groups were less thn the initil torque. This result is consistent with the reports of Hck et l nd Schulte nd Coffey. 37,58 The noninferiority ws shown in the Code 10.2 lloy group, which hd competitive detorque vlue compred to the titnium utment nd could e considered to e employed cliniclly. Moreover, the detorque vlue chnge from cyclic loding in the Code 10.2 lloy ws less thn tht in titnium, nd the men removl torque fter cyclic loding in the Code 10.2 lloy ws lso higher thn tht in titnium. In respect of the removl torque test, the Code 10.2 lloy cn e considered cliniclly cceptle from oth the noninferiority test nd the men comprison. In this study, the reduction rte of detorque vlues fter cyclic loding ws lower thn tht oserved in the study of Kno et l 59 on the premchined gold UCLA utment mde of precious metls in the externl-connection-type implnt. While different mnufcturers might e the cuse for this difference, it ws mostly ttriuted to the different connection types. A study y H et l 60 on the internl-connectiontype implnt identicl to the one used in this study showed tht the internl-hex implnt displyed lower removl torque vlue fter cyclic loding thn the externl-hex implnt, nd the torque reduction rte ws lso higher in the internl connection type. This is likely ttriuted to the shpe of the utment of the internl connection type, which is wedge shpe, nd susequently llows the frictionl force etween the utment nd the implnt to hve greter impct on the implnt screw joint stility thn the prelod of screw. 35 In contrst, in the cse of the externl-connection-type implnt, the implnt screw joint stility mostly depends on the xil prelod of the utment screw. 61 Although the customized utment used in this study ws not one-piece-utment-like solid utment (Solid utment, Strumnn) tht depends entirely on the frictionl force, ut two-piece utment, it ws difficult to tke out the utment from the implnt y hnd fter unscrewing it. After cyclic loding, the utment snk down onto the interior of the implnt, followed y cold welding etween the implnt nd the utment, nd moreover, since the length of the expnded screw ws rther shortened, the prelod ws decresed, which could e n explntion for the lowering of detorque vlues fter cyclic loding in this study. Since the utment mde of precious lloy used in this study s well s the gold UCLA utment is ductile compred to tht mde of nonprecious lloy, slight plstic deformtion occurs, which is more likely to hppen when there is no exposure to oxygen or other rective compounds. 62 Sutter et l 63 reported this phenomenon in the ITI Morse tper design. H et l 64 mentioned tht the cold welding occurred when the detorque vlue ws incresed fter cyclic loding. However, it ppers tht the direct contct reltions etween the utment nd the implnt need to e considered together, rther thn simply defining the cold welding s detorque vlue increse in cse of the internl-connection-type implnt in which the utment is fitted into the implnt y wedge shpe. In this study, the corrosion nd trnish resistnces, mrginl dpttion, nd detorque vlue fter cyclic loding of the Code 10.2 lloy utment were nlyzed in vitro in comprison with the titnium lloy utment. It is considered tht niml experiments under dditionl iologic conditions nd clinicl studies pplied to ctul ptients re necessry efore comprehensive clinicl utiliztion in the future. CONCLUSIONS In order to envisge the clinicl utiliztion of customized utment produced with the Pd-Ag-In lloy (Code 10.2 lloy), mechnicl ccurcy ws evluted y compring it with customized utment produced with conventionl titnium lloy. The Pd-Ag-In lloy hd wrm yellow color nd displyed stle resistnce to discolortion nd corrosion, resulting in n dvntgeous esthetic property. The men microgp etween the implnt nd the utment ws 13.3 µm, nd it did not show noninferiority when compred to the titnium lloy. After long-term use, it displyed sttisticlly significnt noninferiority in the removl torque vlue compred to the titnium group. 98 Volume 31, Numer 1, 2016

8 The customized utment mde of the Pd-Ag-In lloy not only hd n esthetic dvntge ut lso showed stedily fvorle results in the fit of the implnt-utment gp nd detorque vlue. Consequently, it cn help improve clinicl outcomes in nterior implnt restortion. ACKNOWLEDGMENTS This work ws prtly supported y the Technologicl Innovtion R&D progrm of SMBA (SA112600) nd the Bsic Science Reserch Progrm through the Ntionl Reserch Foundtion of Kore (NRF) funded y the Ministry of Science, ICT & Future Plnning (NRF-2013R1A1A ). The uthors reported no conflicts of interest relted to this study. REFERENCES 1. Prithvirj DR, Bhll HK, Vshisht R, Sounderrj K, Prithvi S. Revolutionizing restortive dentistry: An overview. J Indin Prosthodont Soc 2014;14: Priest G. Virtul-designed nd computer-milled implnt utments. J Orl Mxillofc Surg 2005;63: Prk JM, Lee JB, Heo SJ, Prk EJ. A comprtive study of gold UCLAtype nd CAD/CAM titnium implnt utments. J Adv Prosthodont 2014;6: Zndprs R. Digitl imging nd friction. 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