Clinical comparison of ball and socket and locator attachments in implant-assisted cast partial denture: A randomized clinical trial

AIM: To compare the functional, mechanical, biological, and patient-reported outcomes of ball & socket versus locator attachment systems used in implant-assisted cast partial dentures (IACPDs). SETTINGS AND DESIGN: This randomized clinical study included patients with Kennedy Class I and Class II mandibular arches. A total sample size of 20 patients was determined, and allocation to attachment groups was performed. Cone beam computed tomography (CBCT) was used with a radiographic stent for treatment planning, which was subsequently utilized as a surgical guide for implant placement. Prosthetic rehabilitation was carried out using IACPDs designed with Exocad® software (Darmstadt, Germany). MATERIALS AND METHODS: Following implant placement, patients were rehabilitated with IACPDs incorporating either ball and socket or locator attachments. Outcomes were assessed at a 6-month follow-up. Functional parameters: masticatory efficiency. Mechanical parameters: wear of acrylic teeth, nylon ring wear, framework fracture, and dislodgement of the metal retentive housing. Biological parameters: marginal bone level changes assessed using CBCT and soft-tissue health evaluated using periodontal indices. Patient-reported outcomes: assessed using a structured questionnaire. STATISTICAL ANALYSIS USED: All collected data were tabulated and analyzed using SPSS Version 26 (IBM Corporation, Armonk, NY, USA). Independent t-test, Fisher's exact test, and Mann-Whitney U test were used as appropriate. Statistical significance was set at P < 0.05. RESULTS: Nineteen participants completed the study (10 in the ball and socket group and 9 in the locator group), as one participant was lost to follow-up. Functional outcomes: Masticatory efficiency showed a statistically significant improvement in the locator attachment group when analyzed using an independent t-test (P < 0.001). Mechanical outcomes: Mechanical complications assessed using Fisher's exact test revealed no significant intergroup difference (P = 0.370). Biological outcomes: Marginal bone levels decreased significantly from baseline to follow-up within both groups; however, intergroup comparison using the Mann-Whitney U test showed no statistically significant difference (P = 0.584). Periodontal indices demonstrated a statistically significant difference favoring the locator attachment group. CONCLUSION: Within the limitations of this study, implant-assisted cast partial dentures demonstrated favorable functional, mechanical, biological, and patient-reported outcomes, with locator attachments showing superior performance compared to ball and socket attachments.