Relationship between Masseter Muscle Form and Occlusal Supports of Remaining Teeth

Abstract

To chew, it is necessary to maintain harmony between the masseter muscle and other organs. Various studies have been conducted on the masseter muscle, but none has examined the relationships among masseter muscle form, occlusal support of remaining teeth, and maxillofacial morphology. Thus, we conducted the present study using cadavers donated to anatomy practice. After the masseter muscle was extracted, its length, width, thickness, and volume were measured; histological observations were conducted; and the muscle fiber cross-sectional area and muscle density were calculated. In addition, denture use and non-use were examined. The results showed that when regional support loss occurs, muscle fiber thickness and density decrease. This in turn causes masseter muscle thickness and volume to decrease, resulting in muscle atrophy. Furthermore, excluding Eichner class A cases (all regions intact), the thickness of the masseter muscle is greatest when the premolar support region remains. The premolar support region was shown to have the most impact on masseter muscle morphology. These results suggest that atrophy of the masseter muscle can be arrested or improved with the use of dentures in the case of tooth loss.

Influence of lower complete denture use on masseter muscles and masticatory function: A longitudinal study

“…For CD wearers, a pattern of consuming soft foods leads to lower masticatory effort and explains reduced masseter electrical activity . A cadaveric study showed that loss of occlusal support is also associated with atrophy of chewing muscles, primarily the masseters. One in vivo rat study showed that reduced diet consistency and quality indirectly contributes to deterioration in masticatory muscle function and changes in skull form during growing .…”

“…Prosthetic rehabilitation seems to play a crucial role in maintaining masticatory function and preventing muscle atrophy . Tetsuka et al . reported that CD wearers have greater masseter muscle thickness compared to edentulous persons who do not use CDs.…”

“…reported that CD wearers have greater masseter muscle thickness compared to edentulous persons who do not use CDs. However, in this cadaveric study, only the presence or absence of CDs were analysed, making difficult to understand how the use of well‐adapted CDs might influence masseter muscle recovery . Furthermore, a pilot study showed that replacement of old CDs is associated with increased masseter muscle thickness after 3 months.…”

Tooth loss and obstructive sleep apnea signs and symptoms in the US population

“…There are changes in the masticatory muscles that accompany partial as well as complete loss of the teeth. For example, mass of the masseter muscle decreases with increasing loss of teeth [25]. This is attributed to the associated reduction in mandibular stability and masticatory function with progressive loss of teeth, and it is possible that similar reductions occur in the size and strength of other, submental muscles that contribute to both mastication and airway stability during sleep [26].…”

“…Maintenance of occlusal support protects against atrophy of masseter muscle fiber thickness and volume, especially in the premolar region [25]. Moreover, dentures restore the vertical dimension of occlusion, lower facial height, retropharyngeal and posterior airway spaces, and peak inspiratory flow rates [11, 28].…”