COMPARISON OF RETENTIVE PROPERTIES OF FOUR ATTACHMENT SYSTEMS IN MANDIBULAR OVER- DENTURES AT VARYING ANGLES- AN IN-VITRO STUDY

Objectives: To compare initial retentive force of four implant over-denture attachment systems (Locator, OT Equator, Novaloc and CM LOC); at two different angulations; 0° and 20°to the retentive force after one year of simulated use.
Methods: For this cross sectional study, 16 blocks were fabricated, 8 blocks housing the implant analogues and 8 housing over-denture attachment systems. For the 8 blocks with implant analogues, 4 blocks had the implant analogues place at a 20-degree divergence angle and 4 blocks had the implants placed at zero-degrees. The over-denture attachments were tested in a simulated environment of one year at both zero-degree inter- implant placement (parallel) and 20-degree inter-implant placement.
Results: After the stipulated simulation period (1460 cycles) for the implant over-denture attachments on implant analogues placed at 0 degrees, the largest difference in retention was seen in CM LOC, followed by OT Equator, Locator, and Novaloc, respectively, at -25.51(1.42), -15.76 (1.20), -14.43 (2.20), and -11.62 (2.39). For the implant analogues placed at 20 degrees, the largest differences in retention were seen in CM LOC, Locator, Novaloc and OT, respectively, -26.55 (0.90), -19.82 (1.97), -14.18 (2.29) and - 12.46 (2.02).
Conclusions: All samples in this study illustrated a clear reduction in retention after simulated use. A noticeable difference in the amount of reduction between the various attachments was observed and this due to the physical properties of the attachment system and their corresponding design.