Re-osseointegration of peri-implantitis affected and failed implants / 口腔医学

@#Peri-implantitis and implant failure are common issues in the implant dentistry. The contaminated implant can be treated with mechanical, chemical and assisted methods for the formation of re-osseointegration. Re-osseointegration is achievable with valid bone regeneration strategies. The survival rate of implant into the site of previous failure is lower than that of the initial implant. For the hopeless and failed implant, it is necessary to remove the implant with corresponding technique.

Study of the re-osseointegration of implant fixture after mechanical unscrewing / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate whether the re-osseointegration of the implants that had mechanical unscrewing possibly occurred or not. Furthermore, if it happened, the degree of re-osseointegration was evaluated by comparing with previous osseointegration. MATERIALS AND METHODS: The smooth implant (commercial pure titanium 99%) specimens, whose diameter and length was 3.75 mm, 4 mm, respectively were produced. Two implants were inserted into each tibia of 7 New Zealand female white rabbits weighing at least 3.0 kg. The torque removal force for each implant after 6 weeks of implants placement was measured and included in group I . The torque removal forces were assessed after the fixtures were re-screwed to original position and the subjects were allowed to have 4 more weeks for healing and included in group II. One rabbit was sacrificed after first measurement and produced 4 slide specimens in group I, and two rabbits were sacrificed after 2nd measurement, 7 slide specimens, in group II for histomorphologic investigations. All slide specimens were assessed based on the proportion of BIC (bone-implant contact) as well as CBa (Bone area in the cortical passage) value produced by counting the screw threads embedded in the compact bones under the optical microscopic analysis (x20). Statistical analysis was conducted to evaluate the torque removal force, BIC and CBa between group I and II. RESULTS: As for the torque removal force, the result was 10.8 +/- 3.6 Ncm for group I and 20.2 +/- 9.7 Ncm for group II. Furthermore, the torque removal force of group II increased by 98.1% in average compared to group I (P .05), and RT/BIC and RT/CBa between group I and group II were statistically significant (P < .05). CONCLUSION: It is possible to obtain more substantial re-osseointegration within shorter periods than the period needed for the initial osseointegration in case of iatrogenically unscrewed implants.

Investigation of osseointegration according to the healing time after having iatrogenic mobility of implant fixtures / 대한치과보철학회지

PURPOSE: The purpose of this study is to analyze the change in re-osseointegration over time and bone reaction at the interface between implant fixture and the surface of the bone, after destroying re-osseointegration by distorting the bone-implant interface artificially. MATERIAL AND METHODS: Experimental implant fixtures (cp titanium, small ef, Cyrillic3.75 mm x 4 mm) which didn't have surface treatment were produced. Two or three fixtures were implanted on both tibias of twelve female rabbits (New Zealand white, more than 3.5 kg). Then after six weeks, removal torque (RT) was measured and the results were recorded as the first measurement values. The fixtures were submerged again to get reosseointegration between the bone and fixture. To identify the change in re-osseointegration of submerged fixtures over time, six groups had the healing time for four days (group I), one week (group II), two weeks (group III), three weeks (group IV), four weeks (group V) and five weeks (group VI), and then the secondary removal torque was measured for each group. To identify the bone formation under fluorescent light, tetracycline (15 mg/kg, IM) were treated on the rabbits of each group. After the second measurement, the rabbits were sacrificed, and 16 slides were made, two or three for each group. The slides were observed under the fluorescent light with light microscope. To find out the change in the secondary removal torque over the primary removal torque in progress of time, the averages of the increase rate of the primary and secondary torque removal force were calculated. Then, to find out if there were any critical differences between the primary removal torque and the secondary removal torque in each group and among the groups, the results were analyzed statistically by paired t-test, one-way ANOVA, and Duncan's Multiple Range Test. RESULTS: In group I and II, secondary removal torque decreased, especially in group I. In group III, IV, V, and VI, secondary removal torque increased critically. Comparing the differences among the groups, the critical difference was shown between group I, II and group III, IV, V, VI. Mineralization at the interface between the bone and implant fixture was identified from the first week, and bone formation was shown more clearly from the second week. CONCLUSION: If the implant fixture remains unforced for a certain period of time after the fixture has had iatrogenic mobility, re-osseointegration occurs at the surface of the fixture, and for tibias of rabbits, higher re-osseointegration was obtained within two weeks.