2026 Volume 39 Issue 2 Pages 98-106
Purpose: The present study investigated the effects of occlusal contact points of the superstructure on strain, deflection, and gap formation in the collar portion of implants.
Materials and Methods：Implants were fabricated from titanium subjected to severe plastic deformation, and the superstructure (18.5 mm in length, 8 mm in width, and 8 mm in height) was made of quenched steel. Strain was measured by attaching the superstructure to implants inclined at 10°, 20°, and 30° using strain gauges. A universal testing machine applied loads from 50 N to 800 N. Occlusal contact points were identified according to the mesiodistal width (12 mm) of the lower first molar: the central point (C point) of the superstructure, and points A (6 mm from C on the side opposite the tilt) and B (3 mm from C). Gap formation and width were assessed using computer tomography. Five specimens were used for each measurement. Data were analyzed by a one-way analysis of variance followed by significance testing（p＝0.05）.
Results: At point A under a load of 800 N, strains (％) were ≥0.3 at inclinations of 10° and 20°, and ≤0.1 at 30°, with significant differences （p<0.001）. At point B, strains were 0.11 (10°), 0.035 (20°) , and 0.05 (30°) , showing significant differences (p＝0.032) . At point C, strains were 0.18 (30°) , 0.14 (20°) , and 0.1(10°) , with significant differences between 20° and 10°/ 30° (p＝0.020) and between 10° and 30°（p<0.001）. Deflection at point A was greater at 10° and 20° than at 30°, with significant differences (p<0.001) , whereas no significant differences were observed at points B and C. Regarding gap width (μm）, significant differences were found between 24.0 (10°) and 12.0 (20°) at point A (p＝0.002) , while no gaps were observed at points B and C.
Conclusion: Occlusal contact points and implant inclination angles affected strain, deflection, and gap formation in the collar portion of implants.
