BackgroundThe purpose of this prospective cross-over study is to evaluate the effect of bilateral balanced occlusion and canine guidance occlusion on the masseter muscle activity using implant-retained mandibular overdentures.MethodsAfter evaluation of 12 completely edentulous patients using cone beam computed tomography (CBCT), mucoperiosteal flaps were reflected exposing the mandibular interforaminal region. Two implants were placed in the interforaminal region for each of the 12 patients. After a healing period of 3 months, acrylic maxillary complete dentures and mandibular overdentures were fabricated with bilateral balanced occlusion for 6 patients and canine guidance occlusion for the other 6 patients. Electromyographic evaluation of the masseter muscles, during clenching on a silicon index and chewing peanuts and cake, was conducted on the patients after using their dentures for 4 weeks. Each occlusion concept was then converted into the other concept using the same dentures, and the procedure of evaluation was repeated after 4 weeks. The recordings were analyzed statistically using Wilcoxon signed ranks test. p < 0.05 was considered statistically significant.ResultsThe highest electromyographic activity of the masseter muscles was recorded during clenching on a preformed silicon index followed by chewing peanut then cake for both occlusal concepts. The recordings of the masseter muscle associated with canine guidance occlusion were higher than bilateral balanced occlusion but with no statistically significant difference except between the right masseter muscles during clenching (p = 0.042*).ConclusionsBoth bilateral balanced occlusion and canine guidance occlusion can be used successfully in implant-retained mandibular overdentures without affecting masseter muscle activity.

INTRODUCTION: Cleft lip and palate (CLP) affects about 1.5 per 1000 live births (250,000 new cases per year) worldwide. They can be either unilateral or bilateral, complete or incomplete. The bilateral cleft lip and palate (BCLP) deformity typically arises with a protrusive premaxilla. The nasal deformity includes deficient columella, with flared lateral alar cartilages which usually require additional surgeries to improve the nasal symmetry. NasoAlveolar Moulding (NAM) technique, aims to align the alveolus, lip, and nose properly; reduce the severity of the nasal deformity, and lengthen the columella without surgery. OBJECTIVES: The study aims to quantify the effect of NAM therapy, fabricated by CAD/CAM additive manufacturing, in the improvement of nasolabial deformity in terms of bialar width, columellar length and width in infants with complete BCLP. MATERIALS AND METHODS: Ten infants with non-syndromic BCLP (age < 1 month) were selected. Impressions were obtained. The casts obtained from the impressions were scanned using a 3D laser scanner. Designing and 3D printing of the appliances were completed. The appliances were inserted and retained using surgical tapes. Nasal stents were incorporated 60 days after the start of the treatment. Nasal measurements were obtained before treatment and at the end of treatment (after four months). RESULTS: Data was collected and statistically analyzed. After NAM therapy, there was a statistically significant increase in columellar length and a statistically significant decrease in both columellar width and bialar width. CONCLUSIONS: CAD/CAM PNAM therapy has proved its effectiveness in BCLP by showing an improvement in the columellar and bialar presurgical presentation. CAD/CAM PNAM therapy should be considered a routine procedure in the treatment protocol for BCLP.

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