Implant angulation: A measurement technique, implant overdenture maintenance, and the influence of surgical experience

Purpose: The purposes of this study were to develop a technique to measure the angulation between two implants and between each implant and reference planes, to analyze the relationship between the maintenance (adjustments an d repairs) of ball-attachment mandibular implant overdentures and implant a ngulation, and to see if there is any correlation between surgeon experienc e and implant orientation. Materials and Methods: Final casts of 41 patient s who had received two-implant ball-attachment mandibular overdentures were used to measure implant angulations using digital photographs and plane ge ometry. The measured angles were compared with the number of adjustments an d repairs of the prostheses and analyzed by surgeon experience for any tren ds. Results: No significant relationships were found between number of adju stments and repairs and the interimplant angles. However, there was a signi ficantly higher number of repairs when the lingual inclination of an implan t was greater than or equal to 6.0 degrees (P = .033) or if the facial incl ination was < 6.5 degrees (P = .036). Less experienced surgeons had a signi ficantly greater tendency to place implants that diverged from each other i n the frontal plane (P = .045) and with a facial or lingual inclination in the sagittal plane (P = .035). Conclusion: While interimplant angulation di d not appear to affect prosthesis maintenance, individual implants with a l ingual inclination <greater than or equal to> 6 degrees and a facial inclin ation < 6.5 degrees were associated with significantly more prosthesis repa irs. There was a tendency for implants placed by less experienced surgeons to demonstrate greater inclination.