Trial data for precision analysis of a three-dimensional mandibular mechanical advantage.

The data presented in this manuscript describe craniofacial landmark coordinate values, muscle and load moment arm lengths, and mechanical advantage rates for constructing a three-dimensional model of masticatory muscles. Cone-beam computed tomography scans from 30 subjects (aged 12-19 years, 16 females) were used. Thirty-six craniofacial landmarks were identified. Subsequently, the moment arms for 7 muscles and their corresponding load moment arms at incisor and molar positions were determined. Then, the three-dimensional mechanical advantage for each muscle and tooth position was calculated as the ratio of muscle moment arm to load moment arm. This procedure was repeated three times by a main examiner and once by two other examiners. The Friedman test and the square root of the 'method of moments' variance estimator were used to compare data among examiners and calculate random errors, respectively. Although the values for the craniofacial landmark coordinates and biomechanical variables are very close, differences were found between measurements, especially in the interexaminer comparisons. Values served as the basis for reliability (intraclass correlation coefficient) and errors (average mean of absolute differences) analysis in the research paper titled "A three-dimensional method to calculate mechanical advantage in mandibular function: Intra- and interexaminer reliability study," published in the Journal of Orofacial Orthopedics.

Influence of the radius of Monson's sphere and excursive occlusal contacts on masticatory function of dentate subjects.

OBJECTIVE: To determine the influence of the radius of Monson's sphere, the number of posterior laterotrusive, mediotrusive, and protrusive contacts, and the chewing rate on food comminution. DESIGN: Sixty healthy dentate subjects, aged 21.22 ± 2.30 years, were selected. The three-dimensional coordinates of the cusp tips of the lower canine, premolar, and molar teeth were identified from the subjects' digital models. Monson's sphere was designed using the simplex method for function minimisation by adjusting the coordinates on its surface. The contacts were verified using 12 µm metal strips in jaw excursions at 0.5, 1.0, 2.0, and 3.0 mm. The masticatory performance and efficiency, swallowing threshold, and chewing rate were assessed through particle size fractionation. Data were analysed with multiple linear regression (α = 0.05). RESULTS: The sphere's radius, laterotrusive and protrusive contacts at 0.5 mm, and chewing rate were found to be negative predictor variables for masticatory performance until 20 chewing cycles (R2 = 0.429). For 40 cycles, the radius and total contacts (0.5 mm) were also explanatory factors (R2 = 0.223). Only the radius (R2 = 0.176) and the chewing rate (R2 = 0.082) were found to be significant for 60 cycles and swallowing threshold, respectively. Masticatory efficiency was influenced by masticatory performance until 40 and 60 cycles, as well as the radius and total contacts at 2.0 and 3.0 mm (R2 = 0.958). CONCLUSION: A larger radius of Monson's sphere and a greater number of posterior excursive contacts were found to be related to better masticatory function.

Effect of artificial eccentric occlusal interferences on masticatory performance: A randomised double-blind clinical trial.

BACKGROUND: Occlusal interferences lead to changes in mandibular kinematics to compensate and improve function. However, the effects of different types of eccentric disturbance on the comminution capacity are not known. OBJECTIVE: To determine the immediate effect of eccentric occlusal interferences on masticatory performance. METHODS: This crossover clinical trial included 12 healthy dentate subjects aged 25.2 ± 3.3 years who were randomly submitted to seven types of occlusal interference: unilateral and bilateral laterotrusive and mediotrusive, protrusive, dummy and control (no interference). The interference forms were planned in a semi-adjustable articulator, fabricated with composite resin and adhered to the mandibular first molars such that subjects' maximum intercuspation was maintained. Masticatory performance and the chewing rate during 20 cycles were evaluated during subjects' comminution of silicone test food under one interference condition per test day; the multiple sieve method was applied to the comminuted particles. The interference was removed upon test completion, and a 1-week washout period was applied between tests. RESULTS: Comminuted median particle sizes were larger under unilateral (4.94 ± 0.41 mm) and bilateral (4.81 ± 0.49 mm) laterotrusive, bilateral mediotrusive (4.65 ± 0.50 mm) and protrusive (4.83 ± 0.54 mm) interferences (p < .05) than under the control (4.01 ± 0.52 mm) and dummy (4.18 ± 0.58 mm) conditions (p < .05). Only unilateral and bilateral laterotrusive interferences narrowed the comminuted particle size dispersion (p < .05). The chewing rate did not differ among conditions (p = .1944). CONCLUSION: Artificial eccentric interferences had an immediate adverse effect on masticatory performance by resulting in larger comminuted particles. CLINICAL TRIAL REGISTRATION: Brazilian Registry of Clinical Trials (RBR-8g5zfg8).

Self-perceived oral health: a study with patients wearing removable dentures

Aim: This study aimed to investigate the relationship between self-perceived oral health and the prosthetic status of individuals who seek care in prosthodontics clinics. Methods: Self-perceived oral health was analyzed through the Geriatric Oral Health Assessment Index (GOHAI). Abutment tooth mobility was assessed, and denture status was determined by clinical assessment of stability, retention, occlusal balance, vertical dimension, and integrity of dentures. The frequency of individuals in each variable was determined for the low and very low GOHAI conditions. Chi-square, Pearson, and stepwise logistic regression tests were used for the statistical analyses (α = 0.05). Results: Ninety wearers of removable dentures with a mean age of 55.1±9.1 years were evaluated. None of the variables was related to GOHAI values (p > 0.05). The regression analysis showed that age predicts (p = 0.006) the variation of GOHAI conditions (OR = 0.924, CI = 0.873- 0.978), showing only 7.6% protective effect against very low GOHAI. Unsatisfactory stability showed the opposite effect (p = 0.034) and the individuals with this characteristic are more likely (OR = 3.055) to have very low GOHAI scores (CI = 1.085- 8.602). Conclusions: The self-perceived oral health of wearers of removable dentures worsens with age and unsatisfactory stability of dentures

Sensitivity and Specificity of Capsules Containing Fuchsin-Based Beads for the Evaluation of Masticatory Performance.

PURPOSE: To determine the sensitivity and specificity of capsules containing fuchsin-based beads for evaluating masticatory performance. MATERIALS AND METHODS: A total of 60 healthy subjects (mean ± SD age: 41.0 ± 13.2 years) were categorized according to number of occlusal pairs (n = 15 per group) as follows: 16-14 (control group); 13-10; 9-6; and 5-1. The subjects chewed the capsules to assess masticatory performance, which was defined as the concentration of fuchsin released and measured using ultraviolet-visible spectrophotometry. The subjects also comminuted silicone cubes, and median size was calculated via the sieving method. The test foods were compared using analysis of variance, receiver operating characteristic (ROC) curve, and Bland-Altman analysis. RESULTS: The control group presented the highest masticatory performance for chewing the capsules (P < .05), except when compared to the 13-10 occlusal pairs group (P = .667). There was no difference between the partial edentulism groups (P > .05). An acceptable area under the ROC curve of 0.744 was observed, with 73.33% sensitivity and 70.00% specificity. The control group also showed the best results for chewing the cubes (P < .01); however, the 9-6 and 5-1 groups were equivalent (P = .133). An excellent area under the ROC curve of 0.887 was found, with 80.00% sensitivity and specificity. The bias between the capacity of both test foods to recognize subjects with < 10 occlusal pairs was -3.56%. CONCLUSION: Capsules containing fuchsin-based beads were viable for evaluating masticatory performance, as they showed sufficient sensitivity and specificity for characterizing subjects presenting with < 10 occlusal pairs.

Reliability and validity of a new colour-changing test food with an acid-base reaction for the clinical assessment of masticatory performance.

The aim of this study was to determine the reliability and validity of a new test food for the clinical assessment of masticatory performance. The test food had two overlapping acidic/basic halves. Ten dentate subjects chewed one unit for 10-100 cycles. One subject chewed ten units for the same number of cycles. Differences in the L*, a* and b* colour axes were determined before and after chewing by ANOVA. Colour guides were created based on the values of these axes and matched with the number of cycles. The reliability of the guides was evaluated using 30 images, where three examiners indicated the number of cycles in which the colour closest to that of a chewed material was found. The data were contrasted with the real values of the guides to determine the validity (Kappa coefficients). The equivalence of the guides with the median particle size (X50) was determined using equidimensional curves. The test food progressively changed from green to pink during chewing. As the number of cycles increased, the a* values increased and the b* values decreased (p < 0.05). Overall, the guides showed a Kappa value >0.8 for the intra-examiner and inter-examiner reliability and the validity comparisons. The a* and X50 values were inversely proportional to each other, and the b* values showed a direct relationship with the X50 values. The L* values did not show correspondence. The new test food showed high reliability and validity for the assessment of masticatory performance through clinical colour guides matched with the number of cycles and X50.