Clinical, radiographic and economic evaluation of short-6-mm implants and longer implants combined with osteotome sinus floor elevation in moderately atrophic maxillae: A 3-year randomized clinical trial.

AIM: To compare the 3-year clinical, radiographic and economic outcomes of short-6-mm implants and longer implants combined with osteotome sinus floor elevation (OSFE) in the posterior maxilla. MATERIAL AND METHODS: This study enrolled 225 patients (225 implants with diameter of 4.1 mm and 4.8 mm) with a posterior maxillary residual bone height (RBH) of 6-8 mm. Patients were randomly divided into three groups: Group 1 (6 mm implants alone), Group 2 (8 mm implants + OSFE) and Group 3 (10 mm implants + OSFE). The following outcomes were recorded at 1 and 3-year examinations: implant survival, probing pocket depth (PPD), bleeding on probing (BOP), modified plaque index (mPI), marginal bone loss (MBL), biological and technical complications, complication-free survival and treatment costs. RESULTS: At the 3-year follow-up, 199 patients (Group 1: 67; Group 2: 62; Group 3: 70) were re-examined. Implant survival rates were 91.80%, 97.08% and 100.00% in groups 1, 2 and 3. Implant survival rate in Group 1 was significantly lower than that in Group 3 (p = 0.029). A multivariate Cox model showed that the short-6-mm implants with wide diameter had a protective effect on implant survival (hazard ratio: 0.59, p = 0.001). No significant differences in BOP%, PPD, mPI, MBL and complication-free survival rate were found among the three groups. The average costs of retreatment were 8.31%, 1.96% and 0.56% of the total costs in groups 1, 2 and 3. The cost to avoid a 1% increase in implant loss associated with 6-mm implants over a 3-year period was 369 CNY (56 USD) using a 10-mm implant with OSFE and 484 CNY (74 USD) using an 8-mm implant with OSFE. CONCLUSION: In the moderately atrophic posterior maxillae, the three treatments showed acceptable clinical, radiographic and economic outcomes with up to 3-year follow-up. 10-mm implants combined with OSFE showed more favourable implant survival and fewer maintenance costs in comparison with short-6-mm implants, which were less expensive.