การวิเคราะห์ไฟไนต์เอลิเมนต์และการศึกษาเชิงเปรียบเทียบประเภทการเชื่อมต่อรากฟันเทียมในสะพานฟันสามยูนิตแบบยึดด้วยสกรู

Abstract

This study aimed to investigate the effect of different implant–abutment connection types using Finite Element Analysis (FEA). An FEA model was developed to simulate the mechanical behavior of screw-retained three-unit dental implant bridges with three connection types: Case I – Nonhex–Nonhex, Case II – Hex–Nonhex, and Case III – Semi–Semi. The simulation focused on screw loosening under two loading conditions: axial load and inclined load, applied at the second premolar (tooth 45) and the second molar (tooth 47), which are the primary load-bearing positions in clinical practice. Experimental validation was conducted by comparing the FEA results with data from physical tests. The results indicated that Case II (Hex–Nonhex) exhibited the lowest displacement, stress, micromotion, and axial screw movement at both tooth positions, suggesting the lowest potential for screw loosening. In contrast, Case I (Nonhex–Nonhex) showed the highest values for all parameters, particularly at tooth 47 under inclined loading, indicating the highest risk of screw loosening. Case III (Semi–Semi) produced moderate results and may be suitable for tilted implants or cases requiring greater clinical flexibility. During the validation process, the average strain values obtained from FEA were significantly higher than those measured using a Universal Testing Machine (UTM). This discrepancy was likely due to noise and imperfect contact between the loading tip of the UTM and the top surface of the bridge model, which led to lower experimental strain values. Additionally, some material properties used in the FEA model may not have fully matched the actual materials, resulting in overestimated strain values in the simulation.