Evaluation of peri-implant bone density changes in Branemark implants by computer assisted densitometric image analysis (CADIA) / 대한치주과학회지

CADIA(Computer-assisted densitometric image analysis) method is used to analyze bone density changes around the implants. The usefullness and reproducibility of the method was assessed. We tried to find out if there is any possibility to quantitiate and qualitify peri-implant bone density change as time passes. And we concluded that this newly developed linear analysis is efficient for analyzing peri-implant bone density change non-invasively. In this study, 2152 machined Branemark fixtures installed from 1994 to 2002 in the department of Periodontics, Dental hospital of College of Dentistry, Yonsei University were included. Of these fixtures 22 radiographically analyzable failed fixtures were used as experimental group, and 22 successful implants placed in the same patient were used as control group. 1. 57 out of 1635 machined Branemark standard and Mk II implants system failed, the survival rate was 96.5%. And 11 out of 517 machined Branemark Mk III and Mk IV implants system failed, the survival rate was 97.9%. Total survival rate was 96.8%. 2. 22 failed implants were used for the analysis, 10 of which failed before prosthetic treatment due to infection and overheating. 12 failed due to overload after prosthetic treatment, 63.6% of which failed during the early phase of functional loading, i.e. before 1 year of loading. 3. Bone density change values around coronal region of the failed implants were -6.54 +/- 6.35, middle region were -3.53 +/- 5.78, apical region were -0.75 +/- 10.33, resulting in average of -3.71 +/- 8.03. 4. Bone density change values around coronal region of the successful implants were 4.25 +/- 4.66, middle region were 6.33 +/- 5.02, apical region were 9.89 +/-4.67, resulting in average of 6.27 +/- 5.29. 5. There was a statistically significant difference between two groups (p<0.01). In conclusion, the linear analysis method using computer-assisted densitometric image analysis could be a useful method for the analysis of implants, and could be used for future implant researchs.

Consideration of density matching technique of the plate type direct radiologic image system and the conventional X-ray film: first step for the subtraction / 대한치주과학회지

Digital substraction technique and computer-assisted densitometirc analysis detect minor change in bone density and thus increase the diagnostic accuracy. This advantage as well as high sensitivity and objectivity which precludes human bias have drawn interest in radiologic research area. The objectives of this study are to verify if Radiographic density can be recognized in linear pattern when density profile of standard periapical radiograph with the aluminium stepwedge as the reference, was investigated under varies circumstances which can be encountered in clinical situations, and in addition to that to obtain mutual relationship between the existing standard radiographic system, and future digital image systems, by confirming the corelationship between the standard radiograph and Digora system which is a digital image system currently being used. In order to make quantitative analysis of the bone tissue, digital image system which uses high resolution automatic slide scanner as an input device, and Digora system were compared and analyzed using multifunctional program, Brain3dsp. The following conclusions were obtained. 1. Under common clinical situation that is 70kVp, 0.2 sec., and focal distance 10cm, Al-Equivalent image equation was found to be Y=11.21X+46.62 r(2)=0.9898 in standard radiographic system, and Y=12.68X+74.59, r(2)=0.9528 in Digora system, and linear relation was confirmed in both the systems. 2. In standard radiographic system, when all conditions were maintained the same except for the condition of developing solution, Al-Equivalent image equation was Y=10.07X+41.64, r(2)=0.9861 which shows high corelationship. 3. When all conditions were maintained the same except for the Kilovoltage peak, linear relationship was still maintained under 60kVp, and Al-Equivalent image equation was Y=14.60X+68.86, r(2)=0.9886 in the standard radiograhic system, and Y=13.90X+80.68, r(2)=0.9238 in Digora system. 4. When all conditions were maintained the same except for the exposure time which was varied from 0.01 sec. to 0.8 sec., Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9188 to 0.9900, and in general, standard radiographic system showed higher R-square than Digora system. 5. When all conditions were maintained the same except for the focal distance which was varied from 5cm to 30cm, Al-Equivalent image equation was found to be linear in both the standard radiographic system and Digora system. The R-square was distributed from 0.9463 to 0.9925, and the standard radiographic system had the tendency to show higher R-square in shorter focal distances.

The comparison between 2 wide implants and 3 regular implants in mandibular posterior area / 대한치주과학회지

Osseointegrated implants have been established as the standard treatment modality for full/partial edentulous patients since the 1960's, and the long term results for full edentulous patients have proven to be successful. Based on these results osseointegrated implants are now widely used for partial edentulous patients. There has been an increased interest towards the efficacy of wide implants, despite many reports mentioning the lower success rate of wide implants compared to regular implants. Recently, mandibular molar area defects are commonly restored using 2 wide implants, but it is not determined whether which treatment modality-3 regular implants or 2 wide implants-shows superior success rate. In this study, 2 wide implants and 3 regular implants used for the restoration of mandibular molar area are used to compare the survival rate of 1-4 years, and to analyze and compare the failure factors. The following conclusions could be drawn from this study. 1. Wide implants and regular implants showed 94.5% and 97,6% of survival rate respectively. After prosthodontic work, the survival rate was 100% and 98.1% for wide implants and regular implants respectively. 2. 5 failed implants have been removed. 2 wide implants and 1 regular implant have been removed due to failure of osseointegration, 1 wide implant was removed due to abscess formation caused by over-heating, and 1 regular implant was removed due to mechanical failure caused by over-loading within the first year of function. 3. No statistically significant difference was observed with respect to the amount of marginal bone loss of wide and regular implants.(P>0.05) In conclusion, restoration of the mandibular molar area using 3 regular implants was found to be a good treatment modality, and 2 wide implants could be considered a good treatment modality when success factors are taken into account.