Search

Objectives: The aim of this study was to analyse the relationship of mastication and directional asymmetry (DA) of upper facial skeleton in Early Medieval sample from the Mikulčice settlement (Czech Republic)., Design: The settlement is divided into two burial areas of presumably different socioeconomic status: the castle and the sub-castle. The material consisted of 193 individuals (125 castle, 68 sub-castle). The relationship of facial skeleton DA and mastication was analysed by examining tooth wear and mandibular shape by means of 3D geometric morphometrics. Tooth wear of premolars and molars was evaluated using appropriate scoring systems. 3D coordinates of 35 mandibular landmarks were scanned using MicroScribe G2X digitizing system., Results: The results did not reveal any significant differences in tooth wear DA or mandible DA values between burial areas or sexes. Mandibular shape, however, differed significantly between burial areas and sexes. Directional changes of mandibular landmarks supported a right chewing side preference in the sample. Significant relationship between upper facial skeleton DA and mandible DA was recorded., Conclusions: Differences in subsistence between burial areas and sexes did not translate into differences in mandible DA and dental wear. However, mandibular shape analysis revealed prominence of areas affected by masticatory muscles in individuals from the castle. Higher consumption of tough material, such as meat, has been proposed as possible explanation. The right side was found to be preferential for chewing. The relationship between upper facial skeleton DA and mandible DA was concluded to be the result of the compensatory and adaptive function of mandible., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objective: Tooth wear is a basic physiological adjustment mechanism in the masticatory system. Unfortunately, it is not clear what the relationship is between the activity of the masticatory muscles and the tooth hard tissue loss (mainly enamel) in patients with advanced tooth wear. The aims of this study were (1) to compare the occlusion times and (2) to compare the EMG activity in maximal voluntary clench of the masseter and anterior temporalis muscles of patients with advanced tooth wear to the same activity of healthy volunteers., Design: 50 (16F, 34M) patients and 30 (12F, 18M) age matched controls were clinically examined to assess the degree of wear (TWI). Each subject underwent electromyographic analysis (bilateral anterior temporalis, superficial masseter, anterior digastric and sternocleidomastoid muscles) and digital occlusal analysis., Results: Mean values of the electrical potentials of the mandible elevating muscles during clench were higher in the study group compared to the controls. A negative correlation was found between the temporalis and masseter muscle activities during clench and the mean value of TWI (r=-0.383, p=0.009; r=-0.447, p=0.002). Occlusion time was longer in the study group compared to controls (p<0.05)., Conclusions: Mandibular adductors demonstrated lower muscular activities during clenching in the tooth wear patients; however, the cause of this finding is not certain. Prolongation of occlusion time may exacerbate occlusal surfaces wear or excessive wear may prolong occlusion time., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective: The aim of this study was to explore the relationship between dental wear and facial morphology, with particular reference to the occlusal vertical dimension, in modern human skulls., Design: One hundred and three skulls (52 men and 51 women) between the ages of 20 and 50+ years old were studied. The selected skulls were from a modern period (the 17th and the 18th centuries) and included at least one entire condyle and had at least 3 posterior teeth (premolar or molar) in each quadrant to allow for dental articulation. Occlusal wear was evaluated using ordinal scale (0-4) and vertical occlusal dimension was evaluated by measuring upper facial height (UFH), lower facial height (LFH), LFH-to-UFH ratio (L-U-R) and dental wear. Based on the occlusal wear score, two groups were defined: with and without significant wear., Results: Significant relation was observed between age and dental wear (P<0.01). No significant differences were found in the LFH (P=0.847) or UFH (P=0.108) between the two wear groups. In addition, no significant difference (P=0.132) was demonstrated in the LFH-to-UFH ratio between the groups. No difference was observed in the dental wear score between genders (P=0.321)., Conclusion: Within its limitations, this study demonstrated that dental wear does not influence the vertical dimension of occlusion. Our assumption is that the dento-facial complex fully compensates for the dental effects of wear throughout life., (Copyright © 2014 Elsevier Ltd. All rights reserved.)