A review of masticatory muscle function

Area of Science:

• Dental Science
• Biomechanics
• Anatomy

Background:

• Current understanding of masticatory muscle actions during various jaw movements is based on existing reports.
• The relationship between the mandible and maxillae, and the temporomandibular joint (TMJ) condyle-fossa, can be influenced by clinical interventions.
• Altering tooth contacts impacts muscle activity during functional and parafunctional activities.

Purpose of the Study:

• To review and synthesize current knowledge on the actions of major masticatory muscles.
• To explore how alterations in jaw and tooth contacts affect muscle activity.
• To highlight the clinical relevance of understanding masticatory muscle function.

Main Methods:

• Review of current scientific literature on masticatory muscle actions.
• Analysis of muscle activity during clenching, mandibular opening, and unilateral chewing.
• Examination of the effects of altered occlusal contacts and jaw positions.

Main Results:

• Elevator muscles show maximum activity with bilateral occlusal contacts during clenching in centric occlusion.
• Elevator muscles activate together during chewing when occlusal contacts are balanced bilaterally.
• Increased eccentric tooth contacts enhance muscle activity during both chewing and clenching.
• Medial pterygoid muscle action is variable, influenced by chewing pathway and occlusion.
• Inferior lateral pterygoid muscle plays a reciprocal role with the medial pterygoid and aids in condylar bracing.
• Superior lateral pterygoid muscle activity during mandibular closing requires further investigation.

Conclusions:

• Clinicians can modify jaw muscle activity by altering occlusal relationships.
• Predicting the precise outcomes of morphological changes on the muscular system requires further study.
• Understanding masticatory muscle function and its modifiability is essential for effective clinical practice.