The aim of this study was to investigate the relationship between occlusal tooth contact patterns and the tightness of proximal tooth contact (TPTC) during clenching. Twenty young adult volunteers with healthy dentition participated in the study. TPTC between the left second premolar (P2) and the first molar (M1) was measured during clenching at the 50% maximum voluntary contraction level in the intercuspal position (ICP). A silicone impression material was used to make an interocclusal record at the ICP in each subject, and interocclusal records were analysed using an image-processing system. Subjects were classified according to the presence or absence of each type (A, B or C) of occlusal contact. Statistical analysis was performed using the Mann-Whitney U-test. The results of this study exhibited a relationship between B-type contact and the TPTC of maxillary teeth. The experimental group with a lack of B-type contact on maxillary P2 and/or M1 showed a statistically greater TPTC than the group with B-type contact on both of these teeth (P < 0.01). These results suggest that occlusal tooth contact patterns have an influence on TPTC during clenching.

PurposeThe purpose of this study was to evaluate the relationship between masseter muscle thickness, facial morphology, and mandibular morphology in Korean adults using ultrasonography.Materials and MethodsUltrasonography was used to measure the masseter muscle thickness bilaterally of 40 adults (20 males, 20 females) and was performed in the relaxed and contracted states. Facial photos and panoramic radiography were used for morphological analyses and evaluated for correlations with masseter muscle thickness. We also evaluated the correlations of age, body weight, stature, and body constitution with masseter muscle thickness.ResultsIn the relaxing, the masseter was 9.8±1.3 mm in females and 11.3±1.2 mm in males. In the contracted state, it was 12.4±1.4 mm in females and 14.7±1.4 mm in males. Facial photography showed that bizygomatic facial width over facial height was correlated with masseter muscle thickness in both sexes in the relaxed state, and was statistically significantly correlated with masseter muscle thickness in males in the contracted state. In panoramic radiography, correlations were found between anterior angle length and posterior angle length and masseter muscle thickness in females, and between body length and posterior angle length, between anterior angle length and body length, between ramal length and body length, and between body length and condyle length in males.ConclusionMasseter muscle thickness was associated with facial and mandibular morphology in both sexes, and with age in males. Ultrasonography can be used effectively to measure masseter muscle thickness.

Individuals can be motivated by the new system; meanwhile, comparable effects of controlling dental plaque can be achieved.

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Background School children are in a developmental period in which permanent teeth replace primary dentition. It is also a period with a high incidence of gingivitis and caries, which can be improved with adequate tooth brushing. Advances in information technology have led to the development of smart health devices that assist in tooth brushing. We compared the effectiveness of computer-assisted toothbrushing using a toothbrushing instruction (TBI) method called the smart toothbrush and smart mirror (STM) system with that of conventional TBI (verbal instructions) for plaque control in school children. Methods This randomized controlled clinical trial analyzed and compared the reduction of the modified Quigley-Hein plaque index between the two methods in 42 school children. The participants were randomly assigned to the STM system group (n = 21) or conventional-TBI group (n = 21). The plaque indices were evaluated at baseline, immediately after TBI (day 0), and 1 week and 1 month after TBI. Results The STM system and conventional TBI led to an average reduction of 40.50% and 40.57%, respectively, in whole mouth plaque. Reductions in the plaque indices within each tested time period were observed in both groups (P < 0.001), and the mean plaque reduction did not differ between the two groups (P = 0.44). Conclusions The present study tested a computer assisted system for TBI, more studies are needed to confirm its usefulness in different objectives. Clinical relevance The computer-assisted STM system may be an alternative of TBI for children. Trial registration ClinicalTrials.gov (NCT04627324) Registered 13/11/2020—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04627324.

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