Comparative study between different designs of maxillary implant assisted overdenture (in vitro study)

Purpose Evaluate microstrains on peri-implants tissue of different designs of maxillary complete overdenture assisted by different number of implants. Methods Two maxillary epoxy resin models used, for the first model two implants with 4.5 mm diameter and 13 mm length installed in the canine area and two implants with 4.5 mm diameter and 10 mm length installed in the second premolar area and two designs of maxillary overdenture used: group I maxillary implant overdenture (MIOD) assisted by four implants and Group (II) palateless maxillary implant overdenture assisted by four implants, for the second model two implants with 4.5 mm diameter and 13 mm length installed in the canine area and two designs of maxillary over denture used: group III MIOD assisted by two implants and group IV palateless implant overdenture assisted by two implants, four strain gauges used around each implant, bilateral static 100 N vertical load and 65 N oblique load applied on the occlusal surface of each MIOD. Stress meter used to measure the microstrains using software (ED × 10 A). Results The least stress found related to group I under 100 N vertical loading and the highest readings found related to group IV under 65 N oblique loading, under vertical loading stresses recorded in group III was greater than group I, stress in group IV was greater than group II, stress in group II was greater than group I, stress in group IV was greater than group III, under oblique loading, stress in group III was greater than group I, stress in group IV was greater than group II, stress in group II was greater than group I, stress in group IV was greater than group II. Conclusion Removing the palatal part from MIOD could be done in case of using four implants without damaging the prei-implants tissues.