Is the side with the best masticatory performance selected for chewing?

Objective: This study assessed the degree of relationship between masticatory laterality and lateral asymmetry of masticatory performance using silicon pieces enclosed in a latex bag. Design: Forty-two young adults with natural dentition participated in this cross-sectional, observational study. They performed four different masticatory assays, each consisting of five trials of chewing three pieces of silicon for 20 cycles. In one assay, they were asked to masticate unbagged silicon free-style, whilst in the three other assays they were asked to masticate bagged silicon freestyle, unilaterally on the right-hand side and unilaterally on the left-hand side. The preferred chewing side was determined by calculating the asymmetry index for both the free-style assays. Masticatory performance was determined by sieving the silicon particles and the cycle duration was also recorded. Data were analysed using independent samples or paired t-test and linear regression. Results: Masticatory function using the bagged silicon was similar to that using the unbagged silicon. A significant and positive relationship was observed between the preferred chewing side expressed as the asymmetry index and the side with better masticatory performance. Alternate unilateral chewers demonstrated better masticatory performance than unilateral chewers. However, when free-style and unilateral chewing were compared for each subject, unilateral chewing was found to be as efficient as -or even more efficient than - free-style chewing. Conclusions: There is a positive association between the preferred chewing side and the more efficient side. Alternate unilateral mastication per se does not promote better masticatory performance than consistently unilateral mastication

Lack of relationship between masticatory performance and nutritional status in adults with natural dentition

Objective: This study assessed the relation among several aspects of the masticatory function and the nutritional status in adults with natural dentition. Design: One hundred adults with natural dentition participated in this cross-sectional study. They performed one free-style masticatory test consisting of five trials of 20 silicon-chewing cycles. The preferred chewing side was determined by calculating the asymmetry index. Masticatory performance was determined by sieving the silicon particles, and the cycle duration was also recorded. Weight, body water percentage, body fat mass, muscle mass and osseous mass were measured using a portable digital weighing machine. Body mass index (BMI), waist-hip ratio, skinfold thickness and the upper-arm composition were determined. The relation between masticatory function and a nutritional variable were tested using Pearson or Spearman rank correlation coefficients or using analysis of variance or the Kruskal-Wallis H-test and the Mann-Whitney Utest, as appropriate. Results: Whereas body fat percentages for women were significantly higher than for men, the body mass index was higher in men than in women. Participants who were underweight chewed more asymmetrically and more slowly than normal weight or obese participants. A negative correlation was observed between body fat percentage and masticatory laterality. No relation between masticatory performance and any nutritional status indicator was detected. Conclusion: Being underweight and having a low body fat percentage seem to be related to a masticatory lateral asymmetry and to a large cycle duration in young adults with natural dentition. Masticatory performance does not seem to be related to nutritional status

Side switch frequency while masticating different chewing materials, and its relationship with other masticatory behaviors and sensory perceptions.

Objective: This cross-sectional study aimed to establish normative values for masticatory side switch (MSS) frequency in young Mexican adults and to assess the relationship between various indices and MSS frequency when masticating different chewing materials. Design: We enrolled 101 dentate adults and performed four masticatory assays that involved masticating different chewing materials (i.e., two-colored chewing gum, sweet cracker, salty cracker, and bread). Participants were asked to eat and swallow these foods and to chew the gum for 40 cycles and the following indices were determined: MSS index (MSSI), unilateral chewing index, chewing cycle duration, and number of cycles before terminal swallowing. The participants then rated perceived flavor intensity, salivary flow, and muscle fatigue during each trial. Results: The MSSI ranged from 0.03-0.06 (10th percentile) to 0.48-0.54 (90th percentile). A repeated-measures general linear model revealed a mean MSSI value of 0.28 (95 %CI, 0.25-0.30) adjusted by several factors. Male sex, soft food, and the last chewing period were associated with lower MSS frequency. Spearman's test showed a high correlation for the MSSI among the different foods. MSSI correlated negatively with the unilateral chewing index for each chewing material and with number of cycles for the sweet cracker. However, no significant correlation was detected between MSSI and sensory perception. Conclusions: In healthy dentate individuals, the mean MSS relative frequency is 25-30 % with an 80-central percentile of 5-50 % of the maximum possible side changes. Lower MSS frequencies were detected in men, when chewing soft food, and during the final chewing period

Evaluación de la fiabilidad y validez de métodos que determinan el lado de preferencia masticatorio

[spa] Aunque se han reportado diferentes métodos para evaluar el lado de preferencia masticatorio (LPM), su validez sigue siendo desconocida. Este estudio evaluó la fiabilidad mediante un análisis factorial confirmatoria de 8 grupos de métodos que determinaron el lado de preferencia masticatorio (LPM). Material y Métodos: En este estudio transversal y observacional se realizaron dos sesiones a cuarenta y dos adultos jóvenes con dentición natural sana. Se utilizaron treinta métodos diferentes para determinar el LPM cada método utilizó distintos aspectos metodológicos (definición, comida test, técnica utilizada, ciclos evaluados y análisis de datos). Un test-retest se realizó a 10 sujetos para evaluar la repetibilidad y la capacidad discriminativa de cada método. Se realizó un algoritmo de agrupamiento y un análisis factorial confirmatorio para evaluar la validez de los métodos. Resultados: El análisis factorial exploratorio se realizó mediante el algoritmo de agrupamiento “clúster analysis”, de este derivó un dendrograma el cual señaló dos agrupamientos. El análisis factorial confirmatorio dio como resultado dos factores latentes independientes que correspondían a cada agrupamiento. Un factor latente (F1) determinó el LPM y el otro factor latente (F2) determinó la asimetría de la actividad muscular. Los métodos que tuvieron la mejor correlación con el F1 y por tanto mostraron la mejor fiabilidad fueron los que utilizaron el índice de asimetría y silicona como comida test, otro método que tuvo una buena correlación con el F1 fue la escala analógica visual (VAS). Los métodos que utilizaron chicle como comida test o registros kinesiográfico o electromiográficos mostraron una repetibilidad y fiabilidad débil. Conclusiones: En esta población, los métodos de mayor fiabilidad para evaluar el LPM fueron los que evaluaron todos los ciclos masticatorios por medio del índice de asimetría, utilizaron la técnica de visión directa o video y masticaron silicona embolsada (bolo cerrado) o sin embolsar (bolo abierto) como comida test. Otro método que tuvo una alta fiabilidad, además de ser un método subjetivo fue el que utilizó como instrumento el VAS y después de haber realizado una prueba de masticación.[eng] Although different methods to assess the preferred chewing side (PCS) have been reported, their validity remains unknown. This study assessed the reliability of 8 types of methods for determining the PCS by using a confirmatory factor analysis (CFA). Forty-two adults with natural dentition performed two masticatory sessions in this cross-sectional study. Thirty different methods were used to determine the PCS by using different definitions, food tests, techniques of determination, cycles assessed and data analysis. A test-retest was performed in 10 subjects to evaluate the repeatability and the discriminative capacity of each method. Cluster analysis and a CFA were performed to assess the validity of the methods. The CFA supported the two factor structure indicated by the cluster analysis and indicated the independence of two factors. One factor determined the PCS and the other one determined the asymmetry of muscular activity. The method that showed the best reliability used silicone as test food, determined the PCS by direct visualisation or by video-recording and assessed all masticatory cycles using the Asymmetry Index. The self-assessment by means of a visual analogue scale just after done some masticatory tests also showed a high repeatability and validity. Methods which used either chewing gum as a test food or kinesiographic or electromyographic records demonstrated a weak reliability. It may be concluded that several methods for determining the PCS are reliable by using the CFA, one of them is the use of a visual analogue scale to assess the degree of laterality as perceived by the subject

Peripheral, functional and postural asymmetries related to the preferred chewing side in adults with natural dentition

The aim of this cross-sectional study was to determine the preferred chewing side and whether chewing side preference is related to peripheral, functional or postural lateral preferences. One hundred and forty-six adults with natural dentition performed three masticatory assays, each consisting of five trials of chewing three pieces of silicon placed into a latex bag for 20 cycles, either freestyle or unilaterally on the right- or left-hand side. Occlusal contact area in the intercuspal position, maximum bite force, masticatory performance and cycle duration were measured and the lateral asymmetry of these variables was calculated. Laterality tests were performed to determine handedness, footedness, earedness and eyedness as functional preferences, and hand-clasping, arm-folding and leg-crossing as postural lateral preferences. The preferred chewing side was determined using three different methods: assessment of the first chewing cycle for each trial, calculation of the asymmetry index from all cycles and application of a visual analogue scale. Bivariate relationship and multiple linear regression analyses were performed. Among unilateral chewers, 77% of them preferred the right side for chewing. The factors most closely related to the preferred chewing side were asymmetry of bite force, asymmetry of masticatory performance and earedness, which explained up to 16% of the variance. Although several functional or postural lateral preferences seem to be related to the preferred chewing side, peripheral factors such as asymmetry of bite force and of masticatory performance are the most closely related to the preferred chewing side in adults with natural dentition

Reliability of a visual analog scale for determining the preferred mastication side.

Statement of problem: Although the visual analog scale (VAS) is a simple tool for quantitatively measuring symptom perception, no studies have used the VAS to assess the degree of subjective masticatory laterality. Purpose: The purpose of this study was to assess the reliability of the VAS for determining the preferred mastication side (PMS) and to compare it with other methods. Material and methods: A cross-sectional study was conducted in which 42 adults with natural dentition performed 2 masticatory sessions. Eight different methods were used to determine the PMS by combining different definitions, food tests, measurements, and number of cycles assessed. A test-retest was performed in 10 participants to evaluate the reliability of each method using the intraclass correlation coefficient. To assess the validity of the different methods, the Pearson correlations were performed (α=.05) between the 8 methods. Results: Self-assessment using the VAS had the highest reliability; it also had a positive and significant relationship with 6 of the 7 other methods. The method that showed the best validity used bagged silicone as the test food, determined the PMS by video recording, and assessed all masticatory cycles using the asymmetry index. Low reliability was found for methods using the location of gum bolus at standardized time intervals or electromyographic recordings. Conclusions: The VAS provided a highly reliable means of assessing the degree of masticatory laterality perceived by the participant, with a positive and significant correlation with the majority of the other methods

Relationship between jaw movement and masticatory performance in adults with natural dentition

Objective. This study determines the relationship between several characteristics of jaw movement and masticatory performance determined by multiple regression analysis and adjusted for occlusal contact area and bite force. Materials and methods. Forty-two young adults with natural dentition participated in this cross-sectional study. Occlusal contact area was determined at the maximum intercuspal position by scanning interocclusal records. Maximum unilateral force was measured by means of a gnathodynamometer. The height and amplitude of mastication, occlusal glide length, lateral guidance angle, anterior-posterior distance and cycle duration were recorded using the ARCUSdigma II system. Masticatory performance was determined by sieving the Optosil particles resulting from 20 chewing cycles. Results. Median particle size was negatively associated with height of mastication, maximum bite force, occlusal contact area and amplitude of mastication. Stepwise multiple linear regression analysis revealed that the height of mastication and dental guidance angle are the characteristics of jaw movement most closely related to masticatory performance. Conclusions. In adults with natural dentition, a large vertical height of mastication and a small dental guidance angle are the characteristics of jaw movement most closely associated with good masticatory performance, determined by multiple regression analysis and adjusted for occlusal contact area and bite forc

Reliability of a visual analog scale for determining the preferred mastication side.

Statement of problem: Although the visual analog scale (VAS) is a simple tool for quantitatively measuring symptom perception, no studies have used the VAS to assess the degree of subjective masticatory laterality. Purpose: The purpose of this study was to assess the reliability of the VAS for determining the preferred mastication side (PMS) and to compare it with other methods. Material and methods: A cross-sectional study was conducted in which 42 adults with natural dentition performed 2 masticatory sessions. Eight different methods were used to determine the PMS by combining different definitions, food tests, measurements, and number of cycles assessed. A test-retest was performed in 10 participants to evaluate the reliability of each method using the intraclass correlation coefficient. To assess the validity of the different methods, the Pearson correlations were performed (α=.05) between the 8 methods. Results: Self-assessment using the VAS had the highest reliability; it also had a positive and significant relationship with 6 of the 7 other methods. The method that showed the best validity used bagged silicone as the test food, determined the PMS by video recording, and assessed all masticatory cycles using the asymmetry index. Low reliability was found for methods using the location of gum bolus at standardized time intervals or electromyographic recordings. Conclusions: The VAS provided a highly reliable means of assessing the degree of masticatory laterality perceived by the participant, with a positive and significant correlation with the majority of the other methods

Is the side with the best masticatory performance selected for chewing?

Objective: This study assessed the degree of relationship between masticatory laterality and lateral asymmetry of masticatory performance using silicon pieces enclosed in a latex bag. Design: Forty-two young adults with natural dentition participated in this cross-sectional, observational study. They performed four different masticatory assays, each consisting of five trials of chewing three pieces of silicon for 20 cycles. In one assay, they were asked to masticate unbagged silicon free-style, whilst in the three other assays they were asked to masticate bagged silicon freestyle, unilaterally on the right-hand side and unilaterally on the left-hand side. The preferred chewing side was determined by calculating the asymmetry index for both the free-style assays. Masticatory performance was determined by sieving the silicon particles and the cycle duration was also recorded. Data were analysed using independent samples or paired t-test and linear regression. Results: Masticatory function using the bagged silicon was similar to that using the unbagged silicon. A significant and positive relationship was observed between the preferred chewing side expressed as the asymmetry index and the side with better masticatory performance. Alternate unilateral chewers demonstrated better masticatory performance than unilateral chewers. However, when free-style and unilateral chewing were compared for each subject, unilateral chewing was found to be as efficient as -or even more efficient than - free-style chewing. Conclusions: There is a positive association between the preferred chewing side and the more efficient side. Alternate unilateral mastication per se does not promote better masticatory performance than consistently unilateral mastication

Peripheral, functional and postural asymmetries related to the preferred chewing side in adults with natural dentition

The aim of this cross-sectional study was to determine the preferred chewing side and whether chewing side preference is related to peripheral, functional or postural lateral preferences. One hundred and forty-six adults with natural dentition performed three masticatory assays, each consisting of five trials of chewing three pieces of silicon placed into a latex bag for 20 cycles, either freestyle or unilaterally on the right- or left-hand side. Occlusal contact area in the intercuspal position, maximum bite force, masticatory performance and cycle duration were measured and the lateral asymmetry of these variables was calculated. Laterality tests were performed to determine handedness, footedness, earedness and eyedness as functional preferences, and hand-clasping, arm-folding and leg-crossing as postural lateral preferences. The preferred chewing side was determined using three different methods: assessment of the first chewing cycle for each trial, calculation of the asymmetry index from all cycles and application of a visual analogue scale. Bivariate relationship and multiple linear regression analyses were performed. Among unilateral chewers, 77% of them preferred the right side for chewing. The factors most closely related to the preferred chewing side were asymmetry of bite force, asymmetry of masticatory performance and earedness, which explained up to 16% of the variance. Although several functional or postural lateral preferences seem to be related to the preferred chewing side, peripheral factors such as asymmetry of bite force and of masticatory performance are the most closely related to the preferred chewing side in adults with natural dentition