Journal of Dental Medicine

Background and Aim: Digital subtraction Radiography (DSR) is a method of accurate assessing condylar head changes. several studies have been carried out in applying DSR in dentistry, however there is a few number of studies in efficacy of DSR method in assesment of condylar head changes, The aim of this study was to compare panoramic radiography and DSR detecting simulated lesions of the mandibular condyl.

Materials and Methods: this was a process reaserch study, in which two dry human skulls with no obvious temporomandibular joint pathology were used. Osteophytic lesions were simulated using three sizes of bone chips that were placed on the medial portion of anterior and superolateral aspects of the condyle. Osteolytic lesions were simulated making 1 and 2 mm holes using round burr in the central portion of anterior aspect and Lateral pole of the condyle. Panoramic radiographs were prepared with and without the lesions in place. These paired radiographs were digitized and digital- subtraction images of the original panoramic images were obtained. Eight observers evaluated 155 images of each modality for the presence or absence and the type of simulated lesions of the mandibular condyle. Sensitivity, specificity, reliability and measure of agreement were analyzed using kappa test and crossed tables and qualitative variables were assess by chi-square and fisher's Exact test.

Results: Specificity of panoramic and DSR methods were 15.4% and 66.7% respectively. Sensitivity of panoramic and DSR methods were 61.1% and 80.6% for osteophytic lesions and 37.5% and 83.3% for Osteolytic lesions. The percentage of correct decisions made in DSR method was significantly more than conventional panoramic method (82.6% vs 41.9%) (p<0.0001).

Conclusion: Based on the results of this study digital subtraction technique was significantly more accurate than the panoramic radiographs in detection of simulated lesions of the mandibular condyle.

Background and Aim: It is well recognized that implant treatment is common worldwide, but the approach to success is not predictable because of bone loss that occurs around the implants. Also there are many factors affecting crestal bone loss around the implants that one of them is the surgical protocol of implant installation. The purpose of this investigation was to evaluate the amount of crestal bone loss around the Replace implants installed according to submerged and non- submerged treatment protocol.

Materials and Methods: In this study, 11 patients received 34 implants. In each patient (unilateral or bilateral mandible), one of the implants was placed with submerged procedure and in the other one non- submerged procedure was used. In a period of 3 months a temporary partial denture that covered the implants was used. After 3 months the submerged fixture was exposed, impression was performed and fixed prosthesis was fabricated. Loss of crestal bone at each implant was measured. These measurements have been done at surgical times, over a period of 3 months after implant installation and 6 months after the delivery of the fixed prosthesis. The measurement was done with digital subtraction radiography. Data was analyzed by Wilcoxon Signed Ranks test.

Results: Three months after implant placement, submerged groups showed statistically more crestal bone loss (0.65±0.71) than non-submerged (0.41±0.53) group (p=0.02). After 6 months the mean value of crestal bone loss in submerged group was 0.21±0.40 mm and in non submerged group was 0.29±0.49 mm. This data indicated no statistically significant difference between the two groups of implants (p>0.05).

Conclusion: Our results are in accordance with previously published studies and confirm that the value of crestal bone loss in submerged and non-submerged groups after 3 and 6 months were similar and in acceptable limit.