Retentive Properties of TiN-Coated Novaloc and Locator Overdenture Abutments

Objectives: To compare retentive forces of Novaloc-TiN and Locator abutments for 2-implant overdentures after undergoing insertion-removal and compressive cyclic loading to represent masticatory forces equivalent to 1 week, 1, 3, 6 and 12 months of wear.
Methods: Insertion-removal and compression cycles of 2-implant TiN-coated Novaloc and Locator overdenture attachments embedded into 3D-printed acrylic blocks were performed (n=10 each). For compressive cycling, force was applied at the center of the blocks using a Bose ElectroForce Fatigue Testing machine capable of exerting a 66.7-N load per specimen over a sum of 300,000 cycles per sample. The retentive force was recorded at baseline and after certain insertion-removal (23, 270, 540, and 1080) and compression cycles (5k, 25k, 75k, 150k, and 300k). Deformation and crystallization were assessed using micro-computed tomography and differential scanning calorimetry coupled with thermal gravimetric analysis.
Results: Compressive cycling of the 2-implant overdenture yielded a greater retentive force for the Locator attachments relative to the TiN-coated Novaloc system at simulated mastication equivalent to 1 week, 1, 3, 6 and 12 months of wear. However, Locator attachments displayed fluctuating retentive force throughout the 300,000-cycle duration. No significant differences were observed between the retention forces at baseline and following 300,000 cycles with the Novaloc attachment, indicating consistently stable retentive properties throughout the cycling duration. Similar to compressive cycling, Locator is clearly affected by time, whereas values for Novaloc fluctuate much less.
Conclusions: The Novaloc system offers superior durability following compressive cycling, indicating preserved retentive force longevity relative to the Locator overdenture attachments system, despite lower overall retentive force following insertion-removal and cycling tests.