Divergence Correction Associated with Implant Placement: A Radiographic Study

Purpose: To evaluate implant angulations and alignments with neighboring teeth/implants and compare them to angulations and alignments measured with preinsertion surgical gauges. Materials and Methods: Two hundred implants placed freehand were included. For each site, two panoramic radio-graphs were obtained, one with a gauge and one with an implant. The mesiodistal angular relationships between gauge and subsequently placed implant, gauge and gauge (for neighboring implants), gauge and neighboring teeth, implant and neighboring teeth, and gauge and the inferior border of the mandible were measured. Results: The mean gauge-implant discrepancy was -0.72 degrees. The gauge to teeth angulation was -3.95 degrees, the implant-teeth angulation was -4.67 degrees, the gauge-gauge angulation was 0.49 degrees, and the angulation between the gauge and the inferior border of the mandible was 86.86 degrees. Maxillary implants were more divergent than mandibular implants (-9.89 degrees versus -2.14 degrees). Likewise, implants placed away from (opposite) the clinician's side had smaller gauge-implant discrepancies than those placed in the ipsilateral side (-0.94 degrees versus -1.66 degrees). Implant location (incisor, premolar, molar) also affected this angular relationship; implants placed in the anterior region diverged more (-3.96 degrees) than implants placed in premolar (-1.02 degrees) and molar regions (0.06 degrees). Implants that were placed adjacent to teeth had greater divergence than implants placed in an edentulous region (-1.66 degrees versus 0.09 degrees). Likewise, gauges placed in conjunction with shorter implants (10 mm or shorter) were more divergent than those placed in conjunction with longer implants (-8.29 degrees versus -3.259 degrees, respectively). Conclusion: Placement of dental implants, even without the use of a surgical guide, can result in adequate dental implant angular relationships. An implant's location (arch, side, or site) and the presence of adjacent teeth might affect these relationships. Keywords: clinical study, dental implants, implant angulation, presurgical planning, radiography, surgical gauge