Effect of malocclusion on jaw motor function and chewing in children: a systematic review

Abstract

Objective: To investigate the effects of dental/skeletal malocclusion and orthodontic treatment on four main objective parameters of chewing and jaw function (maximum occlusal bite force [MOBF], masticatory muscle electromyography [EMG], jaw kinematics, and chewing efficiency/performance) in healthy children.

Materials and methods: Systematic searches were conducted in MEDLINE (OVID), Embase, and the Web of Science Core Collection. Studies that examined the four parameters in healthy children with malocclusions were included. The quality of studies and overall evidence were assessed using the Joanna Briggs Institute and GRADE tools, respectively.

Results: The searches identified 8192 studies; 57 were finally included. The quality of included studies was high in nine studies, moderate in twenty-three studies, and low in twenty-five studies. During the primary dentition, children with malocclusions showed similar MOBF and lower chewing efficiency compared to control subjects. During mixed/permanent dentition, children with malocclusion showed lower MOBF and EMG activity and chewing efficiency compared to control subjects. The jaw kinematics of children with unilateral posterior crossbite showed a larger jaw opening angle and a higher frequency of reverse chewing cycles compared to crossbite-free children. There was a low to moderate level of evidence on the effects of orthodontic treatment in restoring normal jaw function.

Conclusions: Based on the limitations of the studies included, it is not entirely possible to either support or deny the influence of dental/skeletal malocclusion traits on MOBF, EMG, jaw kinematics, and masticatory performance in healthy children. Furthermore, well-designed longitudinal studies may be needed to determine whether orthodontic treatments can improve chewing function in general.

Clinical relevance: Comprehensive orthodontic treatment, which includes evaluation and restoration of function, may or may not mitigate the effects of malocclusion and restore normal chewing function.

Keywords: Bite force; Chewing performance; Early orthodontics; Electromyography; Jaw kinematics; Mastication; Masticatory muscles.

Fig. 1

PRISMA flow chart showing the database search result and the selection process of eligible studies

Fig. 2

The pooled maximum occlusal bite force (SD) of children with malocclusion compared to malocclusion-free children during the primary and mixed/permanent dentition stages. The figure also shows the relative differences of MOBF between controls and children with malocclusion during the two dentition stages and between the same group during the two dentition stages

Fig. 3

The averaged (standard error of the mean) of the normalized masseter and anterior temporalis muscle EMG activity of children with UPXB compared to crossbite-free children during mandibular resting, chewing, and maximal clenching positions. The result from each group during each behavior, muscle and side was divided (normalized) to the total average of EMG activity of all the muscles and groups combined