Influence of changing the chewing region on mandibular movement

Abstract

Background: In the shortened dental arch condition, little is known of how patients adapt their jaw function during mastication to the new oral environment. This study aimed to investigate the changes in mandibular movements when the chewing region was changed from the first molar to the first premolar. Methods: Thirty clinical residents with natural dentitions were recruited. The subjects were asked to chew a piece of beef jerky using either the first molar or the first premolar on the preferred chewing side. Three-dimensional trajectories of lower incisors and both condyles were analysed using a jaw movement tracking device with six degrees of freedom during the period between the onset and offset of electromyographic bursts from the masseter and anterior temporal muscles. Results: The closing angle of the lower incisors for first premolar chewing was narrower in comparison with that for first molar chewing (p < 0.05). The lengths of the condylar trajectories and the maximum velocities of the condylar movement for first premolar chewing were smaller and slower, respectively, in comparison with those for first molar chewing (both sides; p < 0.01). Conclusions: The mandibular movement during mastication might be changed to adapt the premolar chewing because of a loss of posterior occlusal supports.

The effect of food bolus location on jaw movement smoothness and masticatory efficiency

“…The restoration of masticatory function is an important aim in dentistry when patients present with extensive tooth loss. Some studies have shown that patients may compensate for posterior tooth loss by chewing longer (2), by swallowing larger food particles or by selecting a softer diet (3).…”

Location of main occluding areas and masticatory ability in patients with reduced occlusal support

“…The current finding adds significant evidence that the molar region as the main occluding area may be of primary importance in maintaining the masticatory ability in good condition, regardless of the main occluding area being on either natural teeth or artificial teeth. Hashii et al 9 investigated the changes in mandibular movements when the chewing region was changed from the first molar to the first premolar. The result demonstrated that when the chewing region was changed from the first molar to the first premolar, the chewing cycle referred to as chopping type was predominant, as observed during the chewing of soft food.…”

“…[5][6][7][8] On the other hand, in the partially or fully edentulous condition with reduced occlusal support, the occluding area is considerably limited and the food platform area changes accordingly to enable mastication using the remaining natural teeth as well as the artificial teeth. Hashii et al 9 stated that when the chewing region was changed from the first molar to the first premolar, the patient would be forced to chew with minimal lateral deviation of the mandible in spite of the toughness of the food. Therefore, it is important to know the location of the main occluding area in such patients when providing instructions on how to use their jaws during mastication with reduced occlusal support.…”

Preservation of Hypermobile Teeth by Establishing Posterior Occlusal Support Using Implant Prostheses: A 5‐Year Follow‐Up

“…One study reported that for subjects with RPDs, the main occluding areas were located more anteriorly than those in the group treated with implant prostheses . Others reported that loss of posterior occlusal support was related to condylar displacement and that the food platform area changed accordingly to enable mastication using the remaining natural teeth, so when the chewing region was changed from the first molar to the first premolar, the mandible would be forced to deviate to chew . The abovementioned studies suggested that reduction or loss of posterior occlusal support caused traumatic overloads on the anterior teeth.…”