Survival of conventional dental implants in the edentulous atrophic maxilla in combination with zygomatic implants: a 20-year retrospective study

PURPOSE: Implant-supported prosthetic rehabilitation in the resorbed maxilla is a great challenge. The aim of this study was to determine the survival rate of conventional anterior implants placed in combination with zygomatic implants according to the Brånemark technique, and to identify risk factors for implant failure. METHODS: We collected data retrospectively from 72 consecutive patients who received treatment from 1998 to 2018 at our center, according to Brånemark’s original technique. Kaplan–Meier analysis was conducted to assess survival rate, and a survival regression model was used with the patient as the random factor, applying the Weibull distribution. RESULTS: A total of 236 maxillary anterior implants were included, with a mean follow-up of 12.1 years. Kaplan–Meier analysis showed overall cumulative survival rates of 95.3% at 1 year, 94.8% at 2 years, 93.0% at 5 years, 90.5% at 10 years, 81.6% at 15 years, and 67.7% at 20 years. Survival regression showed an association between bruxism and implant failure as well as implants bearing an overdenture. Implants with length ≤ 10 mm had a significantly lower survival time. No significant association was found between the number of anterior implants and survival rate. CONCLUSIONS: We found acceptable long-term anterior conventional implant survival. Significant risk factors for failure were bruxism, overdentures, and implants shorter than 10 mm.