EVALUATION OF POSTSURGICAL CRESTAL BONE LEVELS ADJACENT TO NON-SUBMERGED DENTAL IMPLANTS

In most of the studies on long-term radiographic evaluations of cresta l bone levels adjacent to dental implants, no baseline radiographs tak en immediately postsurgically had been obtained. The aim of this study was to test the reproducibility of a simple radiographic method for l inear measurements of changes in bone levels and to evaluate changes i n crestal bone levels adjacent to non-submerged ITI(R) implants 1 year following the surgical procedure. From 128 patients enrolled in a cli nical and radiographic longitudinal study 40 patients also had radiogr aphs taken immediately postsurgically. They were, however, not obtaine d as ''identical'' images. The radiographs were mounted onto slides an d projected on a screen. Mesially and distally from 57 implants tripli cate linear measurements of the distance implant shoulder to bone cres t were taken, using known dimensions of the implants as internal refer ence distances. The median difference of 213 (out of 228 possible) dup licate measurements was 0.00 mm (ranging from -1.72 mm to +1.47 mm whe n comparing the second to the third reading). Some 81% of the double m easurements were within +/-0.5 mm and the precision was 0.30 mm. In th e immediate postoperative radiographs the median mesial bone level was located at 2.07 mm (distally 2.19 mm) from the implant shoulder A sta tistically significant amount of bone loss in the first year was obser ved mesially (median=-0.78 mm) and distally (-0.85 mm) (Wilcoxon match ed pairs signed rank test P less than or equal to 0.001). No statistic ally significant influence of the implant location, the implant length , type of the implant (screw; cylinder) was observed (Kruskal-Wallis P >0.05). The age of the patients was not correlated significantly to th e amount of bone loss observed. In conclusion, methodological limitati ons existed when evaluating linear bone changes in non-identical radio graphs using reference dimensions of the implants. The amount of posts urgical bone loss estimated in other studies was confirmed when using an immediate postoperative radiograph as a baseline.