Purpose: To assess the influence of mandibular residual ridge resorption (RRR) on objective masticatory measures of two occlusal schemes: lingualized occlusion (LO) and fully bilateral balanced articulation (FBBA).
Methods: The enrolled patients (n=22) were randomly allocated one set of complete dentures with either LO or FBBA. Maximum occlusal force, masticatory performance (by the MPI), and mandibular movements were measured at 3- and 6-month follow-ups. Mandibular RRR was assessed as the sum of the mandibular bone height at the midline, first premolar region, and least vertical height region, and from the mental foramen to the alveolar crest, measured on panoramic radiographs; the treatment groups were subclassified into severe or moderate RRR subgroups by the value of the sum of individual measurements.
Results: Significant differences were observed in the between-subgroup comparisons (Kruskal-Wallis test) of the MPI (3 months, p=0.01; 6 months, p=0.04) and linear deviation from intercuspal position (anterior-posterior: 6 months, p=0.01; inferior-superior: 3 months, p=0.008; 6 months, p=0.02). The patients with severe RRR in the FBBA group showed a significant decrease in the MPI and increase in linear inferior deviation from intercuspal position at 3 months (post hoc comparison) as well as a significant increase in the linear posterior and inferior deviation from intercuspal position at 6 months.
Conclusions: LO is the preferable occlusal scheme for patients with severe RRR.
Trial registration: ClinicalTrials.gov NCT00959530.
Copyright 2009 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.