Evaluation and comparison of the influence of unilateral posterior and anterior crossbite on the musculo-articular condition of the maxillofacial apparatus

Abstract

Crossbite is characterized by the reverse relationship of one or more teeth and includes many varieties. A peculiarity of the crossbite itself is a characteristic lesion of only one half-arch or both arches bilaterally with an impact on functional structural development. The most frequent and those that have the greatest impact on the functioning of the entire dentition apparatus are unilateral posterior and anterior crossbites. Studying and understanding the impact of crossbite on chewing on the functioning of the maxillofacial apparatus is the way to achieve a healthy stomatogenic system. The purpose of the study is to analyze and compare the impact of unilateral posterior and anterior crossbite on the functioning of the musculo-articular complex and its impact on the occurrence of TMJ dysfunctional conditions. In total, 47 people aged from 7 to 39 years were examined, respectively during the period of variable and permanent bite. Depending on the type of bite, the patients were divided into two groups. The first group included 26 people aged from 7 to 34 years with a unilateral posterior crossbite. The second group included 21 patients aged 7–39 years with an anterior crossbite. Both groups used basic research methods (clinical examination, palpation of masticatory muscles and temporomandibular joints) and additional ones (photometry, axiography, electromyography). This comparative study between unilateral anterior crossbite mastication and unilateral posterior crossbite mastication was performed based on the frequency of masticatory cycles in reverse order and yielded the following data. The results showed that the prevalence of chewing cycles in reverse sequence in anterior crossbite (not involving any posterior premolars and/or molars) was approximately 8–9% on the crossbite side and approximately 7–13% on the healthy side. The percentage of back-to-back masticatory cycles in patients with unilateral posterior crossbite was significantly higher than in healthy or anterior crossbites, showing a prevalence of 59% with soft bolus and 72% with hard bolus. Thus, the impact of a malocclusion on masticatory function depends on the functional role of the teeth involved in the malocclusion, and, accordingly, the impact of the anterior teeth on the masticatory cycle in the frontal plane is significantly different from that of the posterior teeth.