Objective  The main purpose of this article was to determine the correlation of bite force in maximal intercuspal position (MIP) among patient’s perceptions, clinician subjective interpretation, and T-Scan III system. Materials and Methods  Forty-three dental students at Naresuan University (Phitsanulok, Thailand) participated in the study. Subjects were positioned by Frankfurt horizontal plane paralleled to the horizontal plane and asked to bilaterally clenched in MIP. Patient’s perception was evaluated by asking which side of the jaw had heavier bite force (right, left, or equally on both sides). Then, the clinician subjective interpretation was assessed using traditional occlusal indicators. Furthermore, patient’s bite force was analyzed using T-Scan III. Statistical Analysis  Cohen’s weighted kappa test was used to evaluate the correlation of bite force. Results  The best correlation between patient’s perception and T-Scan III was at the ± 7.5% cutoff range with 15 subject agreements. While the best correlation between clinician subjective interpretation and T-Scan III was at ± 5.0% cutoff range with 23 subject agreements. Cohen’s weighted kappa indicated slight agreement between T-Scan III and patient’s perception and fair agreement between T-Scan III and clinician. Conclusions  Clinician subjective interpretation is more clinically reliable than patient’s perception when T-Scan III is used as a gold standard.

Objective The main purpose of this article is to evaluate the disclusion time (DT) in the lateral excursions and protrusion among subjects with Angle’s malocclusions using a T-Scan III system. Materials and Methods One hundred subjects with malocclusions were divided into Class I, Class II division 1, Class II division 2, and Class III (n = 25 per group). All groups’ DT of each excursion was evaluated by a T-Scan III system. Statistical Analysis One-way analysis of variance, followed by a post hoc test, was used to analyze the numerical data at p < 0.05. Results In the respective malocclusions, means ± standard deviations in second(s) of the DT were 2.08 ± 0.65, 2.13 ± 0.74, 2.12 ± 0.72, and 3.19 ± 1.34 during left excursion; 2.15 ± 0.94, 2.58 ± 1.16, 2.37 ± 1.07, and 3.28 ± 1.25 during right excursion; and 1.88 ± 0.99, 2.08 ± 1.11, 2.07 ± 0.68, and 3.01 ± 1.53 during protrusion. When compared to Class I and Class II malocclusions, Class III showed a significantly higher mean DT of each excursion (p < 0.05). Conclusion Class III had the significantly highest mean DT of each excursion and the significantly longest DT in all excursions.

Objective The aim of this study was to compare the muscle activity of the masseter muscle (MM) and anterior temporal muscle (TA) of patients with skeletal Class I and III during maximum voluntary clenching (MVC) at the intercuspal position (ICP) and during chewing. Materials and Methods Twenty patients were divided into Steiner's skeletal Class I and III groups. MM and TA activity during each task was measured by using surface electromyography. Averaged MM and TA activity during both tasks, symmetry of each muscle activity, synergy between ipsilateral MMs and TAs, and muscle effort were compared. Statistical Analysis Means and standard deviations of intergroup variables were compared by an independent sample t-test for parametric evaluations or by the Mann–Whitney U test for nonparametric evaluations. A probability value of p less than 0.05 was considered significant. Results Averaged MM activity and muscle synergy during MVC at the ICP in skeletal Class III patients were lower than that in skeletal Class I patients. Neither symmetry nor muscle effort during both tasks was different. Conclusion Masticatory muscle performance of skeletal Class III patients was inferior to that of skeletal Class I patients.

Objective To evaluate and compare the first tooth contact region, occlusion time, time to generate total force, and force distribution between open bite (OB) and non-OB (NOB) patients at the maximum intercuspation position using the T-Scan III system. Materials and Methods Sixteen patients were divided into the OB and NOB groups (n = 8 for each group). The T-Scan III system was used to evaluate the first tooth contact region, occlusion time, time to generate total force, and force distribution. Statistical Analysis The mean patient age, overjet, overbite, occlusion time, and time to generate total force were compared between the groups by independent samples t-test. Relative force distributions between groups and among regions were compared by the Mann–Whitney U- and Kruskal–Wallis H-tests, respectively. A probability value of less than 5% (p < 0.05) was considered significant. Results Differences in the first tooth contact region between groups were observed. The molar region was the first tooth contact region in the OB group, while first tooth contact was observed in all regions in the NOB group. Neither the occlusion time nor the time to generate total force was significantly different between the groups (p > 0.05). The highest force distributions were observed in the molar regions in both groups. Significant intragroup differences were found among all regions (p < 0.05), except between the anterior and premolar regions in the NOB group (p = 0.317). Intergroup differences in the force distributions in the anterior (p = 0.000), premolar (p = 0.038), and molar (p = 0.007) regions were significant. Conclusion Unlike in the NOB group, in which first tooth contact occurred in every region, in the OB group, first tooth contact occurred only in the molar region. Compared with those in the NOB group, the force distributions in the OB group were approximately 1.5 times higher in the molar region but were significantly lower in the anterior and premolar regions.

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