Morphometric Comparison of Two Implants with Different Macrogeometries Placed Immediately in the Anterior Maxilla-A Randomized Clinical Trial with up to 6 Months of Follow-up.

PURPOSE: To compare the morphometric results of immediate implants with a cylindrical (conventional) or triangular neck placed in Type 1C sockets in the anterior maxilla, with 6 months of osseointegration. MATERIALS AND METHODS: This prospective randomized clinical trial comprised 20 individuals randomly assigned to each group (10 triangular-neck implants and 10 cylindrical-neck implants). Consecutively, direct measurements were performed: before (T-1) and after (T0) tooth extraction, after implant placement (T1), after 1 month of submerged implant healing (T2), when placing the healing abutment (T3), after placing the definitive crown (T3c), and after 6 months of osseointegration (T4). RESULTS: A significant difference in the buccal cortical thickness was identified between T1 and T3 (0.49 +/- 0.86 mm). Although there was a significant increase in the buccal cortical thickness in both implants, this increase was greater for the triangularneck implants (0.08 +/- 0.59 mm for cylindrical vs 0.90 +/- 0.91 mm for triangular). It was also observed that implants placed below the buccal bone crest (</= -1 mm) promote less vertical buccal bone loss than implants placed >/= -1 mm, at crest level (-0.65 +/- 0.52 mm vs -1.42 +/- 0.86 mm, respectively). This observation needs to be further investigated in additional studies. CONCLUSIONS: The triangular-neck implants showed an increase in the cortical buccal thickness compared to the cylindrical implants. However, this increase does not fully compensate the remodeling after tooth loss.