[A comparative analysis of the clinical effects of implant-supported three-unit splinted crowns versus fixed bridges for the restoration of mandibular posterior teeth to provide references for clinical restoration options].

Objective: To compare the clinical outcomes of implant-supported three-unit splinted crowns and fixed dental prostheses in the posterior mandible, and to provide evidence to support clinical decision-making in restorative treatment selection. Methods: A retrospective study was conducted on 195 patients (96 males and 99 females; aged 28-69 years) with multiple missing posterior mandibular teeth who received implant-supported restorations at the Implant Center, Capital Medical University School of Stomatology, between January 2008 and December 2014. According to the type of restoration, patients were divided into a fixed partial denture group (99 cases, 198 implants) and a splinted crown group (96 cases, 288 implants). Implant survival rates and prosthesis success rates were compared between the two groups. Clinical parameters, including bleeding index (BI), plaque index (PLI), probing pocket depth (PPD), and gingival index (GI), were evaluated. The incidence of mechanical complications (veneering ceramic chipping, screw loosening, and framework fracture) and biological complications (peri-implantitis and marginal bone resorption) was recorded and statistically analyzed. Patient satisfaction was also assessed. Results: The implant survival rates in the fixed partial denture group and splinted crown group were 99% (196/198) and 100% (288/288), respectively, and the prosthesis success rates were 95% (94/99) and 98% (94/96), with no statistically significant differences between groups (χ²=2.92, P=0.087; χ²=1.24, P=0.265). No significant difference in PPD was observed between the two groups (t=0.25, P=0.805). BI, PLI, and GI scores in the splinted crown group (1.61±0.79, 1.17±0.32, and 1.37±0.29, respectively) were significantly lower than those in the fixed partial denture group (2.25±0.80, 1.28±0.40, and 1.99±0.41, respectively) (t=5.62, P<0.001; t=2.12, P=0.035; t=12.16, P<0.001). The incidence of mechanical complications was significantly higher in the fixed partial denture group [18% (18/99)] than in the splinted crown group [8% (8/96)] (χ²=4.09, P=0.043). No statistically significant difference was found in the incidence of biological complications between the two groups (χ²=0.69, P=0.406). Patient satisfaction scores for denture esthetics, function, and comfort in the splinted crown group [(4.61±0.62), (4.49±0.69), and (4.57±0.62) points, respectively] were significantly higher than those in the fixed partial denture group [(4.05±0.53), (4.13±0.56), and (4.21±0.63) points, respectively] (χ²=6.79, P<0.001; χ²=4.01, P<0.001; χ²=4.02, P<0.001). Conclusions: For three-unit implant-supported restorations in the posterior mandible, splinted crown restorations demonstrate advantages over fixed partial dentures in oral hygiene maintenance, reduction of mechanical complications, and patient satisfaction, and may therefore be considered a preferable option in clinical practice.