OAIID:oai:osos.snu.ac.kr:snu2007-01/102/2008003883/1SEQ:1PERF_CD:SNU2007-01EVAL_ITEM_CD:102USER_ID:2008003883ADJUST_YN:NEMP_ID:A078517DEPT_CD:861CITE_RATE:0FILENAME:J Korean Acad Prosthodont 2007 45(3) 339-44.pdfDEPT_NM:치의학과EMAIL:pros53@snu.ac.krSCOPUS_YN:NCONFIRM:

Han, Jung-Suk

Kim, Sung-Hun

Lee, Jai-Bong

Yang, Jae-Ho

Yeo, In-Sung

여인성

The Journal of Korean Academy of Prosthodontics

SNU Open Repository and Archive

339COMPARISON BETWEEN TIUNITETM AND ANOTHER OXIDIZED IMPLANT USING THE RABBIT TIBIA MODELIn-Sung Yeo1, D.D.S., M.S.D., Jai-Bong Lee2, D.D.S., M.S.D., Ph.D., Jung-Suk Han3, D.D.S, M.S.D., Ph.D., Sung-Hun Kim4, D.D.S., M.S.D., Ph.D.,Jae-Ho Yang5, D.D.S., M.S.D., Ph.D.1Graduate student, Department of Prosthodontics, School of Dentistry, Seoul National University2Professor, Department of Prosthodontics, School of Dentistry, Seoul National University3Associate Professor, Department of Prosthodontics, School of Dentistry, Seoul National University4Assistant Professor, Department of Prosthodontics, School of Dentistry, Seoul National University5Professor, Department of Prosthodontics, School of Dentistry, Seoul National UniversityStatement of problem. Various anodic oxidation techniques can be applied to dentalimplant surfaces. But the condition for optimal anodized surfaces has not been described yet.Purpose. The purpose of this investigation was to compare an implant that was oxidized byanother method with TiUniteTM through resonance frequency analysis and histomorphome-try.Material and methods. Turned (control), TiUniteTM and another oxidized fixtures, which usedCa2+ solution for anodic oxidation, were placed in the tibiae of 5 New Zealand White rabbits.The bone responses were evaluated and compared by consecutive resonance frequencyanalysis once a week for 6 weeks and histomorphometry after a healing period of 6 weeks.Results. At the first week, both oxidized implants showed significantly higher implant sta-bility quotient (ISQ) values than the control. No significant differences in resonance fre-quency analysis were found between the two oxidized groups for 6 weeks. The means and stan-dard deviations of bone-to-implant contact (BIC) ratios were 71.0 ± 4.2 for TiUniteTM, 67.5 ±10.3 for the Ca2+-based oxidation fixture, 22.8 ± 6.5 for the control. Both oxidized implants weresignificantly superior in osseointegration to the turned one. There was, however, no statisti-cally significant difference between the two oxidized implants.Conclusion. TiUniteTM and the Ca2+-based oxidation fixture showed superior early bone responsethan the control with respect to resonance frequency analysis and histomorphometry. No sig-nificant differences between the oxidized groups, however, were found in this investigationusing the rabbit tibia model. Key WordsAnodic oxidation, Surface modification, Dental implant, Resonance frequency analysis,HistomorphometryJ Korean Acad Prosthodont : Volume 45, Number 3, 2007Dental implants have been an excellent andpopular treatment option in restoring singly,partially and fully edentulous areas. However, thedental implant material, commercially pure tita-nium itself requires much time for osseointe-gration. In order to achieve better and morerapid bone response to implant surfaces, varioussurface modifications have been introduced1-3.Anodic oxidation is one of them.Machined titanium implants with anodizedpoly-crystalline, thick oxide and a microporousroughness and structures on the submicro- andmicrometer level (TiUniteTM, NobelBiocare,Gthenburg, Sweden) have shown good experi-mental results4-6. But the optimum surface chem-istry about anodic oxidation has not been con-firmed and is still under study7-8. In another oxi-dized implant, which used Ca2+ solution foranodic oxidation (Osstem Co., Pusan, Korea),the chemical composition of the solution andother conditions for oxidation are known to beslightly different from those of TiUniteTM althoughthe exact formulation including voltage and cur-rent is not known. The surface properties of theoxide such as thickness, microstructure, andcomposition depend on different process para-meters including electrolyte composition, anod-ic potential, electric current, temperature, andelectrode geometry9. The purpose of this inves-tigation is to test and compare biocompatibilitiesbetween two differently oxidized dental implantsusing the rabbit tibia model.MATERIAL AND METHODSThirty threaded and turned titanium (gradeIV) dental implants with a length of 7 mm and adiameter of 3.75 mm were used in this study. Theimplants were divided into 3 groups: TiUniteTM,the Ca2+-based oxidation, and turned (control)implants.This investigation using animals was approvedby the Animal Research Committee of SeoulNational University (approved number: SNU-061003-1) and all experimentation was done inaccordance with the Institute of LaboratoryAnimal Resources (ILAR) guidelines of SeoulNational University (SNU). Five New ZealandWhite rabbits, weighing 3.0 to 3.5 kg, were usedin this investigation. Prior to surgery, the shavedskin in the proximal tibial area was washed withBetadine and preoperative antibiotics, 0.12 gkanamycin IM, was administered prophylactically.Rabbits were anesthetized with a combination ofketamine (28.8 mg/kg) and xylazine (11.7 mg/kg)intramuscularly. Local anesthesia with 1.8 ml of2% lidocaine was administered in the regionsplanned for surgery. The proximal aspect of eachtibia was surgically exposed via skin incisionand the muscles were dissected to allow elevationof the periosteum. The flat surface on the medi-al aspect of the proximal tibia was selected forimplant placement. The implantation holes weredrilled with a low rotational speed, profusesaline irrigation and with successively increasingdiameters, no countersink preparation, and final-ly tapped with a 3.3 mm tap. Three types ofimplant were installed at each tibia. The implantspenetrated the first cortical layer only, with twothreads visible above the cortex. The periosteumand fascia were sutured with chromic gut and theskin was sutured with silk. Each rabbit recoveredwithout complications and received 0.06 gkanamycin IM per day for three days postoper-atively.Huang et al10 concluded that resonance fre-quency analysis (RFA) was a reliable and accuratemethod for early assessment of the osseointe-gration process with respect to implant stability.For RFA, the rabbits were anesthetized with thesame method above once a week for six weeks. The340suture silk was removed and only the skin was dis-sected. Then, implant stability quotient (ISQ)values were measured by OsstellTM (IntegrationDiagnostics Ltd., Gteborgsvgen, Sweden). The skinwas resutured with silk after measurement.At the sixth week, all the rabbits were anes-thetized, the ISQ values were measured andthen the rabbits were sacrificed in a carbon diox-ide chamber. The fixtures were surgically removeden bloc with an adjacent bone collar and imme-diately fixed in 4% neutral formaldehyde. The spec-imens were processed to be embedded in light-cur-ing resin (Technovit 7200 VLC, Kultzer, Wehrheim,Germany). Un-decalcified, cut and ground sectionswere prepared using the Exakt� system (ExaktApparatebau, Norderstedt, Germany) based ona method described by Donath11. The specimenswere ground to an approximate thickness of 30 μmand stained with hematoxylin and eosin (HE-staining). An IBM personal computer connectedto an Olympus BX microscope (Olympus, Tokyo,Japan) and image analysis software (ImageAnalysis, Bildanalysis, Stockholm, Sweden) wasused for calculating the percentage of bone-to-implant contact (BIC). All light microscopic cal-culations were made with a 10 objective and 10 eye-pieces. The highest percentage of BIC in the twoconsecutive threads was calculated.The statistical significance of the differencesin RFA and BIC ratio among the groups wasassessed by one-way ANOVA and Scheffe’spost hoc analysis. Values of P < .05 were consideredto be statistically significant.RESULTSAll rabbits recovered from anesthesia. Slightinflammation at skin was found during the mea-surement for RFA but neither inflammation norinfection of the bone was noted.Fig. 1 shows the means of ISQ values for eachimplant group. The ISQ values for TiUniteTMkept increasing for 6 weeks while those for the con-trol group decreased at the first week of healing(Fig. 1 and Table I). Both the anodized implantsshowed significantly higher ISQ values than thecontrol at the healing period of the first week (P< .05). There was almost no significant differ-341Table I. The means and standard deviations of ISQ values for each groupWeek(s) TiUniteTM Ca2+-based oxidation Turned0 69.5 ± 1.3 68.4 ± 2.6 67.4 ± 3.01 69.7 ± 1.4 69.4 ± 1.1 64.2 ± 6.32 71.0 ± 1.8 68.8 ± 2.3 66.0 ± 5.73 71.1 ± 2.7 70.5 ± 1.8 68.0 ± 3.24 71.6 ± 3.2 69.9 ± 1.9 69.3 ± 2.25 71.2 ± 3.0 70.3 ± 2.7 68.1 ± 2.96 73.7 ± 3.7 71.5 ± 2.2 69.3 ± 2.6Fig. 1. The means of ISQ values for each implantgroup.ence between TiUniteTM and the Ca2+-based oxi-dation fixtures. However, because TiUniteTMshowed significantly higher ISQ values than thecontrol (P < .05) at the second and sixth weeks,while the Ca2+-based oxidation and the controlimplants showed no significant difference, TiUniteTMwas considered to be slightly superior in RFA tothe Ca2+-based oxidation fixture although nei-ther of the anodized groups was found to besignificantly different in resonance frequencymeasurements from each other.The means and standard deviations of bone-to-implant contact (BIC) ratios were 71.0 ± 4.2 forTiUniteTM, 67.5 ± 10.3 for the Ca2+-based oxidationgroup, and 22.8 ± 6.5 for the control (Fig. 2 andTable II). TiUniteTM and the Ca2+-based oxida-tion fixtures showed better osseointegration (P <.05) than the turned implant (Fig. 3). There was nosignificant difference in BIC between the twoanodized groups.DISCUSSIONThe resonance frequency analysis told thatTiUniteTM was superior in early implant stabilityand maintenance of it. The Ca2+-based oxidationimplant showed similar but more various resultsthan TiUniteTM although both the anodizedimplants reported better resonance frequencyvalues than the control group. Slightly fluctuat-342Table II. The means and standard deviations of BIC ratios for each groupTiUniteTM Ca2+-based oxidation TurnedBIC ratio (%) 71.0 ± 4.2 67.5 ± 10.3 22.8 ± 6.5Fig. 3. The means and standard deviations of bone-to-implant contact ratio for each implant group.(a)                         (b)                            (c) Fig. 2. Histologic views at 100 magnification for each implant group: (a) TiUniteTM (b) Ca2+-based oxidation (c) Turned.ed ISQ values were reported in the Ca2+-based oxi-dation fixture, which indicated such an implantsystem can have a problem in early bone responseand achieving proper stability. More investigationsabout biocompatibility, implant designs and sur-face characteristics seem to be required.Although the means and standard deviations ofBIC ratios were slightly different maybe becauseof the differences in experimental conditionsand healing periods, this investigation reportedthe results that were similar to those of others5-6.Both the anodized implants showed similar bone-to-implant contact ratios that were significantlysuperior to the control after six weeks of healing.For RFA, however, TiUniteTM was thought to bebetter than the Ca2+-based oxidation group, con-sidering ISQ value-comparisons with the con-trol in spite that there was no significant differencebetween the two oxidized implants, as men-tioned above. Implant stability is an important fac-tor for implant success. Some authors10,12-13 report-ed that osseointegration was related to implant sta-bility. But this experiment indicated that other fac-tors than surface modification can be importantto keep the fixture stable. Sul, et al8 discussed var-ious conditions for anodic oxidation and tried tofind the optimum surface properties of oxidizedimplant because surface characteristics of dentalimplants directly influenced osseointegration.Therefore, more studies about factors to con-tribute to implant stability, optimal surface prop-erties of anodic oxidation and the relation betweensurface characteristics and clinical meanings areneeded.CONCLUSIONThis in vivo investigation concluded the fol-lowing:1. For RFA, the ISQ values for TiUniteTM keptincreasing for 6 weeks while those for thecontrol group decreased one week after instal-lation. At the first week of healing, both the oxi-dized implants showed significantly higher ISQvalues than the machined one, which meantsuperior early stability. However, at the sixthweek, TiUniteTM was considered better than theCa2+-based oxidation fixture, considering ISQvalue-comparisons with the control althoughthere was no significant difference between thetwo oxidized implants.2. For histomorphometry, the means and standarddeviations of BIC ratios were 71.0 ± 4.2 forTiUniteTM, 67.5 ± 10.3 for the Ca2+-based oxi-dation group, and 22.8 ± 6.5 for the control.TiUniteTM and the Ca2+-based oxidation implantsshowed significantly higher BIC ratios than theturned implant. No significant difference wasfound between the two oxidized groups.REFERENCES1. Ellingsen JE. Surface configurations of dental im-plants. Periodontology 2000 1998:17;36-46.2. Cooper LF. A role for surface topography in cre-ating and maintaining bone at titanium endosseousimplants. J Prosthet Dent 2000;84:522-534.3. Klokkevold PR, Nishimura RD, Adachi M, CaputoA. Osseointegration enhanced by chemical etchingof the titanium surface: A torque removal study inthe rabbit. Clin Oral Impl Res 1997;8:442-447.4. Larsson C, Thomsen P, Aronsson BO, Rodahl M,Lausmaa J, Kasemo B, Ericson LE. Bone responseto surface-modified titanium implants: studieson the early tissue response to machined andelectropolished implants with different oxidethicknesses. Biomaterials 1996;17:605-16.5. Kim YH, Koak JY, Chang IT, Wennerberg A, HeoSJ. A histomorphometric analysis of the effectsof various surface treatment methods on os-seointegration. Int J Oral Maxillofac Implants2003;18:349-56.6. Albrektsson T, Johansson C, Lundgren AK, Sul YT,Gottlow J. Experimental studies on oxidized im-plants: a histomorphometrical and biomechanicalanalysis. Applied Osseointegration Research2000;1:21-4.7. Sul YT, Johansson CB, Albrektsson T. Oxidized ti-tanium screws coated with calcium ions and theirperformance in rabbit bone. Int J Oral Maxillofac343Implants 2002;17:625-34.8. Sul YT, Johansson C, Wennerberg A, Cho LR,Chang BS, Albrektsson T. Optimum surface prop-erties of oxidized implants for reinforcement of os-seointegration: surface chemistry, oxide thick-ness, porosity, roughness and crystal structure. IntJ Oral Maxillofac Implants 2005;20:349-59.9. Hall J, Lausmaa J. Properties of a new porous ox-ide surface on titanium implants. AppliedOsseointegration Research 2000;1:5-8.10. Huang HM, Chiu CL, Yeh CY, Lin CT, Lin LH, LeeSY. Early detection of implant healing processusing resonance frequency analysis. Clin OralImpl Res 2003;14:437-43.11. Donath K, Breuner C. A method for the studyon undecalcified bones and teeth with attached softtissue. J Oral Pathol 1982;11:318-25.12. Rasmusson L, Meredith N, Cho IH, Sennerby L. Theinfluence of simultaneous versus delayed placementon the stability of titanium implants in onlaybone grafts: a histologic and biomechanics studyin the rabbit. Int J Oral Maxillofac Surg 1999;28:224-31.13. Meredith N, Alleyne D, Cawley P. Quantitative de-termination of the stability of the implant-tissue in-terface using resonance frequency analysis. Clin OralImpl Res 1996;7:261-7.Reprint request to:JAE-HO YANG, D.D.S., M.S.D., PH.D.DEPARTMENT OF PROSTHODONTICS, SCHOOL OF DENTISTRY,SEOUL NATIONAL UNIVERSITY28 YONKON-DONG, CHONGRO-GU, SEOUL, 110-749, SOUTH KOREAjhoyang@snu.ac.kr344

Comparison between TiUniteTM and another oxidized implant using the rabbit tibia model

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Comparison between TiUniteTM and another oxidized implant using the rabbit tibia model

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