ADJUSTMENTS AND COMPLICATIONS OF MANDIBULAR OVERDENTURES RETAINED BY 4 IMPLANTS - A COMPARISON BETWEEN SUPERSTRUCTURES WITH AND WITHOUT CANTILEVER EXTENSIONS

Purpose: The aims of the study were to evaluate the postinsertion care needed by patients treated with four implants to retain mandibular ov erdentures and to compare two types of superstructures. Materials and Methods: The study consisted of 54 patients who had been treated with conventional maxillary dentures and mandibular overdentures retained b y four implants and a triple-bar superstructure with cantilever extens ions (28 patients) or without cantilever extensions (26 patients). Dif ferences between both groups with regard to age, gender, length, and d iameter of the implants and preoperative mandibular bone height were t ested by means of Student's t and chi-square tests with a probability level of 0.05. No significant differences were found. Both groups were retrospectively compared on adjustments and complications. The follow -up period after insertion of the dentures was 2 years. Results: Durin g the 2-year follow-up, 17 patients of the cantilever-extension group and 20 patients of the group without cantilever extensions needed adju stments, and 17 patients of the cantilever group and 12 patients of th e group without cantilever extensions had to be treated because of com plications. Significantly more (P < 0.05, chi-square test) superstruct ure fractures were present in the cantilever group (14 occasions in 7 patients) than in the group without cantilever extensions(1 occasion). All superstructure fractures in the cantilever group involved the can tilever extensions. Conclusion: This study demonstrated a considerable need for postinsertion care, confirming the necessity of routine foll ow-up services for patients restored with implant-retained overdenture s. Furthermore, the results of this study suggest restriction of the u se of cantilever extensions.