Adaptation of a dental RadioVisioGraph unit as a laboratory animal research tool.

We have adapted the RadioVisioGraph (RVG), a digital radiography system designed for dentistry, to become a versatile research tool in a small research facility. We have used this modified digital imaging system in our institution to assess bone fractures and ossification in rabbit tibias in which titanium posts were placed in close proximity to one another, to evaluate bone fill in rats with experimental cranial critical-size defects, and to ensure the proper placement of oral gavage tubes in rodents. This method provides instantaneous digital radiographs, thus not requiring a dedicated X-ray suite or film-processing equipment, and reduces scatter radiation by < or =95%. The use of this technology in a small research facility has greatly improved the quality of both the care our animals receive and the research data we obtain.

The effect of dental implant spacing on peri-implant bone using the rabbit (Oryctolagus cuniculus) tibia model.

PURPOSE: This study investigated the effects of implant proximity on inter-implant bone height, density, and osseointegration using digital radiography and histology. MATERIALS AND METHODS: After a feasibility study, a total of 80 endosteal implants were placed in 20 New Zealand White Rabbit tibias. With the aid of a surgical jig, four 8.5-mm implants were placed in the medial aspect of the tibial crest at inter-implant distances of approximately 1, 1.5, and 3 mm. Standardized digital radiographs using a paralleling device were made immediately after placement of implants. Implants were allowed to osseointegrate for 90 days. After this healing period, the animals were sacrificed, and the standardized radiographs were repeated. The tibias were harvested, processed, and invested in epoxy. Sagittal sections were made from each specimen for histologic evaluation. The initial and postmortem digital radiographs were evaluated for inter-implant distances, vertical bone height changes over time and between implant pairs, and bone density changes over time and between implant pairs using a computer image analysis program and computer statistics program. RESULTS: The actual inter-implant distances were consistent in a range of 0.2 mm. Bone height increased significantly from presurgical levels at all 3 locations (p < .0005). Repeated measures analysis of variance comparing change in bone height at the 3 implant pair distances showed significant differences among the 3 (p = .002). Paired t tests showed that the amount of bone growth at the 1-mm separation site was significantly greater than the 1.5-mm site (p = .026) and the 3-mm site (p = .001), whereas bone growth at the 1.5- and 3-mm sites did not show significant differences (p = .162). A repeated measures analysis of variance comparing change in bone density showed no significant differences (p > .05) among the 3 inter-implant distances for either the 8-mm position (approximately crestal bone height) or the 6-mm position (approximately 2 mm subcrestal). CONCLUSION: Within the limits of this study, it seems placing implants closely together does not adversely affect bone height or density. Conversely, it seems that placing implants closer together may increase bone growth.