Stability of crestal bone level at platform-switched non-submerged titanium implants: a histomorphometrical study in dogs.

Objectives: To investigate the influence of platform switching on crestal bone level changes at non-submerged titanium implants over a period of 6 months.
Material and Methods: Titanium implants (n=72) were placed at 0.4 mm above the alveolar crest in the lower jaws of 12 dogs and randomly assigned to either matching or non-matching (circumferential horizontal mismatch of 0.3 mm) healing abutments. At 4, 8, 12, and 24 weeks, dissected blocks were processed for histomorphometrical analysis. Measurements were made between the implant shoulder (IS) and the apical extension of the long junctional epithelium (aJE), the most coronal level of bone in contact with the implant (CLB), and the level of the alveolar bone crest (BC).
Results: At 24 weeks, differences in the mean IS-aJE, IS-CLB, and IS-BC values were 0.2 +/- 1.2, 0.3 +/- 0.7, and 0.3 +/- 0.8 mm at the buccal aspect, and 0.2 +/- 0.9, 0.3 +/- 0.5, and 0.3 +/- 0.8 mm at the lingual aspect, respectively. Comparisons between groups revealed no significant differences at either the buccal or the lingual aspects.
Conclusions: It was concluded that (i) bone remodelling was minimal in both groups and (ii) platform switching may not be of crucial importance for maintenance of the crestal bone level.