Influence of Premature Exposure of Implants on Early CrestalBone Loss: An Experimental Study in DogsFatigue Characteristics of Five Types of Implant-AbutmentJoint DesignsJe-Hyeon Yoo, Byung-Ho Choi, Jingxu Li, Han-Sung Kim, Chang-Yong Ko, Feng Xuan, Seung-Mi JeongOral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;105:702-6Il-Song Park, Sang-Yong Won, Tae-Sung Bae, Kwang-Yeob Song, Charn-Woon Park, Tae-Gwan Eom, Chang-Mo JeongMet. Mater. Int. 2008;14(2):133-8Objective:Introduction:This study evaluated the fatigue limit of five implantabutmentcombinations (<strong>Osstem</strong> Implant Co. Korea). Thefatigue tests were performed to evaluate the impact offatigue on the effectiveness of dental implant-abutmentassembiies with different joint designs and with differentabutment materials, with a special emphasis on the patternof the dental implant fixture and the abutment, as well asthe effect of the abutment material on the stability of thejoint area.Results & Conclusions:The mean static strength of the EXZR<strong>TS</strong> group was largestat 1772.2 N and that of the INTIWS group was smallest at893.8 N. Turkey analysis showed that the group with theabutment joint with the external hexagonal structurepattern had a significantly higher mean static strength thanthe group with the internal hexagonal structure pattern (p
The Effect of Various Thread Designs on the Initial Stabilityof Taper ImplantsEffect of Casting Procedure on Screw Loosening of UCLAAbutment in Two Implant-Abutment Connection <strong>System</strong>sJu-Hee Park, Yiung-Jun Lim, Myung-Joo Kim, Ho-Beom KwonJ Adv. Prosthodont 2009;1:19-25Chun-Yeo Ha, Chang-Whe Kim, Young-Jun Lim, Myung-Joo KimJ Kor Acad Prosthodont 2008;46(3):246-54GS <strong>System</strong> Pre-Clinical StudyStatement of problem:Primary stability at the time of implant placement is relatedto the level of primary bone contact. The level of bonecontact with implant is affected by thread design, surgicalprocedure and bone quality, etc.Purpose:The aim of this study was to compare the initial stability ofthe various taper implants according to the thread designs,half of which were engaged to inferior cortical wall of typeIV bone (Group 1) and the rest of which were not engagedto inferior cortical wall (Group 2) by measuring the implantstability quotient (ISQ) and the removal torque value (RTV).Material & Methods:In this study, 6 different implant fixtures with 10 mmlength were installed. In order to simulate the sinus inferiorwall of type IV bone, one side cortical bone of swine ribwas removed. 6 different implants were installed in thesame bone block following manufacturer's recommendedprocedures. Total 10 bone blocks were made for eachgroup. The height of Group 1 bone block was 10 mm forengagement and that of group 2 was 13 mm. The initialstability was measured with ISQ value using Osstellmentor TM and with removal torque using MGT50 torquegauge.Results:In this study, we found the following results. 1. In Group 1 withfixtures engaged to the inferior cortical wall, there was nosignificant difference in RTV and ISQ value among the 6 typesof implants. 2. In Group 2 with fixtures not engaged to theinferior cortical wall, there was significant difference in RTV andISQ value among the 6 types of implants (p < .05).There was significant difference in RTV and ISQ valueaccording to whether fixtures were engaged to the inferiorcortical wall or not (p< .05). 4. Under-drilling made RTV andISQ value increase significantly in the NT implants whichhad lower RTV and ISQ value in Group 2 (p < .05).Conclusions:Without being engaged to the inferior cortical wall fixtures hadinitial stability affected by implant types. Also in poor qualitybone, under-drilling improved initial stability.Statement of problem:The cast abutment has advantages of overcomingangulation problem and esthetic problem. However, whena gold-machined UCLA abutment undergoes casting, theabutment surfaces in contact with the implant may change.Purpose:The purpose of this study was to compare the detorquevalues of prefabricated machined abutments with goldpremachinedcast-on UCLA abutments before and aftercasting in two types of internal implant-abutmentconnection systems: (1) internal hexagonal joint, (2) internaloctagonal joint. Furthermore, the detorque values of twoimplant-abutment connection systems were compared.Material & Methods:Twenty internal hexagonal implants with an 11-degreetaper and twenty internal octagonal implants with an 8-degree taper were acquired. Ten prefabricated titaniumabutments and ten gold-premachined UCLA abutmentswere used for each systems. Each abutment was torquedto 30 Ncm according to the manufacturer’s instructions anddetorque value was recorded. The detorque values weremeasured once more, after casting with gold alloy forUCLA abutment, and preparation for titanium abutments.Group means were calculated and compared usingindependent t-test and paired t-test (α= .05).Results:The results were as follows: 1. The detorque values betweentitanium abutments and UCLA-type abutments showedsignificant differences in internal octagonal implants (p < .05),not in internal hexagonal implants (p > .05). 2. In comparison ofinternal hexagonal and octagonal implants, the detorque valuesof titanium abutments had significant differences between twoconnection systems on the initial analysis (p < .05), not on thesecond analysis (p > .05) and the detorque values of UCLAtypeabutments were not significantly different between twoconnection systems (p > .05). 3. The detorque values oftitanium abutments and UCLA-type abutments decreasedsignificantly on the second analysis than the initial analysis ininternal hexagonal implants (p .05).Conclusions:Casting procedures of UCLA-type abutments had no significanteffect on screw loosening in internal implant-abutmentconnection systems, and UCLA-type abutments showedhigher detorque values than titanium abutments in internaloctagonal implants.GS <strong>System</strong> Pre-Clinical StudyA B C D E FA BTable 1. Components and dimensions of tested specimensFig. 1. Characteristics of thread design used in this study.A. GS III (<strong>Osstem</strong>, Seoul, South Korea),B. Osseotite NT (3i, Floria, USA),C. Replace Select (Noble Biocare, Goteborg, Sweden),D. Sinus Quick (Neoplant, Seoul, South Korea),E. US III (<strong>Osstem</strong>, Seoul, South Korea),F. Hexplant (Warantec, Seoul, South Korea.)Fig. 2. A. 6 implants ware installed with engageing (Group 1).B. 6 implants were installed without engaging (Group 2).Internal hexaGroup 1(Titanium abutment)Group 2(UCLA-type abutment)Internal octaGroup 3(Titanium abutment)Group 4(UCLA-type abutment)ImplantfixturesGSⅡ(4.0×10.0mm)SSⅡ(4.1×11.5mm)ArticlenumberTypes ofabutmentsArticlenumberTransferGSTA5620abutment (hex)GS2R4010R01GoldCastGSGA4510Sabutment (hex)SS2R1811SS ComOctaabutment (octa)ComOcta Goldabutment (octa)SSCA485COG480SFig. 1. Internal hexagonal implants,abutments and abutmentscrews (group 1: Titaniumabutment, group 2: UCLA-typeabutment).Fig. 3. Titanium abutments afterpreparation (group 1: internalhexagonal implant, group 3:internal octagonal implant).Fig. 2. Internal octagonal implants,abutments and abutmentscrews (group 3: Titaniumabutment, group 4: UCLA-typeabutment).Fig. 4. UCLA-type abutments aftercasting procedure (group 2:internal hexagonal implant,group 4: internal octagonalimplant).3233
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