Effect of Inter-Implant Angulation on Bone Height Around Two Implants Assisting Mandibular Complete Overdenture.

Purpose: This study aimed to evaluate the effect of inter-implant angulation on the bone height around two implants assisting mandibular complete over denture retained by locator attachment. Materials and Methods: A total of 6 edentulous male patients delivered mandibular complete over denture assisted by two canine implants. After construction of complete dentures, the patients were classified into two equal groups: Group I received axial implants while Group II received 15° distal inclined implants. Radiographic assessment was done immediately (T1), six months (T2) and twelve months (T3) following insertion of definite overdenture. The peri-implant bone height changes were calculated during the 1^st six months (T1-T2) and 2^nd six months (T3-T2) months of study. Results: The mean values of vertical peri-implant bone resorption of Group I during the 1^st six months (0.873± 0.009 mm) and in Group II (1.093± 0.016 mm) was found to be statistically significant. Also, the means of vertical peri-implant bone resorption of Group I during the 2^nd six months was (0.591± 0.012 mm) and in Group II (0.605±0.004 mm) was found to be statistically significant. The means of horizontal peri-implant bone resorption of Group I during the 1^st six months (0.173± 0.014 mm) and in Group II (0.2± 0.012 mm) was found to be statistically significant. Also, the means of horizontal peri-implant bone resorption of Group I during the 2nd six months was (0.061±0.001 mm) and in Group II (0.073±0.003 mm) was found to be statistically significant. The means of vertical peri-implant bone resorption during the (12 months) of study in Group I (1.464± 0.015 mm) and in Group II (1.698± 0.014 mm) was found to be statistically significant. The means of horizontal peri-implant bone resorption during the (12 months) of study in Group I (0.234± 0.013 mm) and in Group II (0.273± 0.014 mm) was found to be statistically significant. Conclusion: (1) The 15° distally inclined implants inserted in the canine areas for assisting mandibular complete overdenture may induce peri-implant bone loss more than the axially inserted implants. (2) Immediate loading accelerates the initial alveolar bone loss around implants used for assisting mandibular complete overdenture.  Recommendations: Other elongated studies must be conducted with more number of patients using other evaluation methods to compare between axially and non-axially inserted implants following delayed loading concept to assist mandibular complete overdenture.