[Chewing pattern in posterior crossbite. Classification of chewing pattern in the frontal plane].

Occlusion is one of the most important factors to affect chewing movement. In this study, chewing movements of subjects who have posterior crossbite were recorded to analyze the relationship between chewing pattern and crossbite occlusion. Chewing movements of 22 subjects of posterior crossbite and 5 normals were recorded with Sirognathograph Analysing System II. Subjects were to chew soft gum; on each specified side, both at the posterior crossbite region and at another resion of the side. On the other hand, normal subjects were to chew only on each side. Chewing patterns were classified into several specific ones examined with chisquare test concerning the relationship between chewing pattern and occlusion. From the results we obtained following conclusion. 1. Frequency of normal chewing pattern, posterior crossbite group is lower than normal group. 2. Among the posterior crossbite group, specific patterns are found with highly frequency such as 'Concave Type', 'Crossover I Type', 'Crossover II Type' and 'Reverse Type'. 3. By segmental chewing at the posterior crossbite region, 'Normal Type' and 'Concave Type' are lower and 'Crossover I Type', 'Crossover II Type' and 'Reverse Type' are higher in frequency in comparison with posterior crossbite side voluntary chewing. 4. By segmental chewing at the posterior crossbite resion, 'Normal Type' and 'Concave Type' are lower and 'Crossover I Type', 'Crossover II Type' and 'Reverse Type' are higher in frequency in comparison with segmental chewing at non-crossbite resion.