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

Reference values and reliability of occlusal force distribution and occlusal time measured by the T-Scan system in adults with healthy dentition

PURPOSE

Reference values of occlusal characteristics are needed to interpret the data obtained using the T-Scan System. This study aimed to establish reference values for and to assess the reliability of, occlusal force distribution in the maximal intercuspal position and the occlusion time in young adults with healthy dentition.

MATERIALS AND METHODS

In total 178 adults with natural dentition participated in this retrospective cross-sectional study, of whom 76 performed a retest session. Several occlusal recordings were obtained from each participant using the T-Scan system while asking them to bite two or three consecutive times (multi-bite) or only once (single-bite) at the maximal intercuspal position. The lateral and anteroposterior occlusal force distribution were determined as percentages in the right and posterior teeth . Occlusion time was measured in seconds. After the occlusal force distribution and occlusion time percentiles were calculated, reliability was assessed by the intraclass correlation coefficient.

RESULTS

The 5th-95th percentiles for occlusal force distribution were 34%-67% on the right teeth and 55%-94% on the posterior teeth. The 90th percentile for multi-bite occlusion time was 0.17 s and for single-bite occlusion time was 0.27 s. The intraclass correlation coefficients for lateral occlusal force distribution, anteroposterior occlusal force distribution, multi-bite occlusion time, and single-bite occlusion time were 0.70, 0.68, 0.58, and 0.67, respectively.

CONCLUSIONS

This study generated reference values for key occlusal characteristics (occlusal force distribution and occlusion time) when using the T-Scan system. These values showed moderate reliability.

Influence of masticatory side switch frequency on masticatory mixing ability and sensory perception in adults with healthy dentitions: A randomized crossover trial

STATEMENT OF PROBLEM

The advantages and disadvantages of frequently changing sides while masticating remain unclear.

PURPOSE

The purpose of this clinical study was to determine the effect of varying the frequency of masticatory side switches on masticatory mixing ability and sensory perception in dentate adults.

MATERIAL AND METHODS

This nonblinded, randomized 12-period crossover study, conducted at Barcelona Dental School from January to March 2022, included 36 healthy adults with natural dentitions (median age, 23.5 years; 26 women). Participants were randomly allocated to 12 sequences and performed 12 masticatory assays masticating a 2-colored gum for 40 cycles each using the following masticatory styles as interventions: freestyle, unilateral right, unilateral left, and switching sides 5%, 15%, and 25%. The primary outcome was the mixing ability index (MAI), defined as the standard deviation of the red channel intensity of the masticated gum in the color-histogram plugin of the ImageJ software program. Participants also rated the perceived flavor intensity and salivary flow on a visual analog scale. Data were analyzed by repeated measures analysis of variance (α=.05).

RESULTS

The MAI was similar for all masticatory styles (P=.63). Participants perceived greater flavor intensity (mean difference: 8%, 95% CI: 1% to 15%) and salivary flow (mean difference: 11%, 95% CI: 0% to 21%) with 25% side switching compared with freestyle or unilateral mastication.

CONCLUSIONS

Frequently switching the masticatory side while masticating gum does not alter the mixing ability, but it appears to enhance salivary flow and flavor intensity.

Comparative analysis of masseter muscle electrical activity by nasal patency in children with rhinitis and asthma: a pilot observational study

PURPOSE

This pilot cross-sectional study aimed to evaluate differences in electromyographic activity patterns of the masseter muscle according to the nasal patency in children with rhinitis and asthma.

METHODS

The study included 43 children aged 5-14 years with rhinitis and/or asthma. Patients underwent peak nasal inspiratory flow (PNIF) measurement to assess nasal patency, and electromyographic evaluation of the right and left masseter muscles during chewing and at rest. Electromyographic activity patterns according to nasal patency were compared using the Mann-Whitney test, and effect sizes were measured using the Glass rank biserial (rb) correlation. A p-value of < 0.05 was considered statistically significant.

RESULTS

No significant differences in electromyographic activity of the masseter muscle at rest, during unilateral chewing, or during habitual chewing were found between the groups. However, we found that patients with low nasal patency had a median electric activity of the right masseter muscle during maximum contraction of 60.53 (51.74-72.43), while those with adequate nasal patency had a median of 77.40 (56.71-88.45). Although the difference in myoelectric activity between the groups did not reach statistical significance (p = 0.061) at the adopted significance level of 5%, the size of the difference between groups were considered moderate (rb = 0.338) and a potential association between nasal patency and the muscular function of the masseter muscle could be suggested.

CONCLUSION

The study found no differences in the electromyographic activity of the masseter muscle at rest, during unilateral chewing, or during habitual chewing among children with rhinitis and asthma based on nasal patency. Further research with larger sample sizes is needed to validate these findings and gain a better understanding of the impact of nasal patency on the muscular function of the masseter muscle.

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).

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.

Association of masticatory efficiency with deep carious lesions in children

PURPOSE

Masticatory efficiency is defined as an individual ability to grind and pulverize food material, and can be influenced by many factors. This research aimed to investigate the association between masticatory efficiency and deep carious lesion.

METHODS

The research included 48 children (24 male, 24 female) aged from 3 to 14 years. Participants were allocated to two groups; children with no or with only incipient carious lesions were included in the first group (ICDAS levels 0, 1, or 2), and children with bilateral deep carious lesions that are ICDAS levels 4, 5, and 6 were included in the second group. Information on dental parameters (dental status, ICDAS level of each carious lesion), and level of pain (Wong-Baker scale) were collected from each participant. Participants chewed Optosil® test food for 20 masticatory cycles, and chewed particles were analyzed by the optical scanning method.

RESULTS

There is a significant difference in masticatory efficiency variables (number of chewed particles, minimal and maximal Feret diameter, Sauter mean diameter, a mean and total surface of particles) between groups. A positive significant correlation is observed between WBS level and time needed for masticatory performance in a group of children with deep carious lesions.

CONCLUSION

Deep carious lesions in children are associated with a decrease in masticatory efficiency. Moreover, children with carious lesions that provoke a higher level of pain take more time for masticatory cycles.

Comparative evaluation of hemispheric and masticatory laterality in complete dentures with two occlusal schemes - A prospective cohort study

Purpose

The lateralization can influence the choice of occlusion scheme, patient comfort and success of the prosthesis. The existence of favored masticatory side in complete denture patients and its influence with various occlusal schemes is less analyzed in the literature. The study objective was to compare the masticatory and hemispheric laterality in complete denture subjects rehabilitated with 2 different occlusal schemes at different time intervals.

Methodology

The cohort study recruited 26 patients in each group of balanced and non-balanced occlusion with definitive criteria. Conventional procedures were followed in denture fabrication. The hemispheric and masticatory laterality for all participants were established at 0,1,3- and 6-month intervals. The laterality was categorized as preferred chewing side (CPCS), predominant preferred chewing side (PPCS) and observed preferred chewing side (OPCS). The data on chewing side preference was analyzed by chi square test. (α = 0.05).

Results

Right side preference was predominant in 86.1% of non-balanced and 60.1% of balanced occlusion participants. The side preference among the 2 laterality and across time interval decreased in masticatory laterality of balanced occlusion participants (P < .05) when compared to non-balanced occlusion. (P > .05).

Conclusion

The balanced occlusion dentures had lesser masticatory side preference when compared to non-balanced occlusion complete denture.

Does Orthodontic Treatment Change the Preferred Chewing Side of Patients with Malocclusion?

Whether orthodontic treatment can change the preferred chewing side (PCS) is unknown. This study examined (1) if the PCS changes after orthodontic treatment and (2) which factors contribute to this change. Two hundred fifty patients who visited the orthodontic clinic at Tokyo Medical and Dental University Hospital between 2017 and 2020 were included in the study. Mandibular kinesiograph (MKG) was taken at pre- and post-treatment, and PCS was determined. Patients who showed a change in PCS to the opposite side and those who showed no change in PCS at post-treatment were pooled into the PCS-changed and PCS-unchanged groups, respectively. The demographic, clinical, and cephalometric parameters were compared between the groups. Significant factors associated with changes in were of age < 20 years at the beginning of orthodontic treatment (odds ratio (OR), 2.00), maximum lateral mandibular movement to PCS ≥ 10.0 mm at pre-treatment (OR, 6.51), and change in occlusal canting of ≥1.0° (OR, 2.72). The predicted probability of change in PCS was 13.2%, 36.0%, and 67.5% for no factor, one factor, and two factors associated with PCS change, respectively. Orthodontic treatment may change PCS due to patient age, maximum lateral mandibular movement to PCS, and change in occlusal canting.

Effect of side switch frequency on masticatory performance and rhythm in adults with natural dentition: A randomized crossover trial

BACKGROUND

The relationships between the frequency of masticatory side switches (MSS) and other aspects of masticatory function are not clear.

OBJECTIVES

In this study, we determined the effect of MSS frequency on masticatory performance and rhythm in dentate adults and explored the between-subject relationships among side switch frequency, masticatory rhythm, and laterality.

METHODS

In this crossover study, subjects performed six masticatory patterns of five trials each, chewing bagged silicone for 20 cycles. The six patterns were freestyle, unilateral right, unilateral left, and switching sides one, three, and five times. Masticatory performance and rhythm were determined for each style by median particle size (MPS) and chewing cycle duration, respectively. In the freestyle mastication pattern, masticatory laterality was assessed by the unilateral chewing index and the frequency of MSS was assessed by the MSS Index. Data were analyzed using Friedman's test and repeated-measures analysis of variance.

RESULTS

We included 29 participants (15 women; median age, 23 years). No significant between-subjects differences in the MPS were detected obtained by switching one, three, or five times per trial. Chewing cycle duration increased with the MSS number per trial. During freestyle mastication, the MSS Index was inversely correlated with the unilateral chewing index (Rho -0.569; 95%CI -0.25 to -0.78; P=0.001; Spearman test), but not with the MPS or chewing cycle duration.

CONCLUSION

Differences in MSS frequency do not affect masticatory performance, but they do alter the masticatory rhythm. Individuals with a higher MSS frequency also have a more symmetrical chewing pattern.

The Law of Minimum Vertical Dimension: Evidence for Improvement of Dental Occlusion

The law of minimum vertical dimension (MVD) states that “when the mandible moves to reach the maximum intercuspal position, this always involves bringing the mandible and maxilla as close together as possible.” Therefore, after the first occlusal contact is made, the MIP will be reached through reduction of the vertical dimension. Our objective of this study, through an integrative review of the literature review, was to determine whether ignoring this law is a factor that contributes to malocclusion, temporomandibular joint dysfunction, and recurrences of functional orthodontic and orthopedic treatments.We conducted a search of the literature in five of the main electronic scientific databases. The following medical subject heading terms were used in our search: centric relation, dental occlusion, malocclusion, vertical dimension, and mastication. We cross-referenced the descriptors in the following four groups: centric relation and maximum intercuspation; occlusal plane and malocclusion; neuro-occlusal rehabilitation; and vertical dimension and unilateral chewing. From this, we selected 277 potentially eligible articles. Out of these, 209 were excluded in accordance with the exclusion criteria already described. Thus, 65 studies were included in the qualitative synthesis.The articles were also classified according to their impact factor and degree of recommendation, in conformity with the table of the Oxford Centre for Evidence-Based Medicine. The scientific interest in the scope of the articles was also assessed by using three charts developed according to year and country of publication and the percentage of publication. Unilateral chewing creates a vicious cycle of damage that leads to an ever-increasing masticatory deficiency. Most of the articles chosen for this review confirmed that noncompliance with law of MVD was a predisposing factor in cases of relapse, in functional orthodontic and orthopedic treatments, as well as a causal factor in malocclusion and in functional and morphological TMJ dysfunctions.

Variation in dental occlusal schemes two years after placement of single-implant posterior crowns. A preliminary study

Some authors have recommended that implant-supported single crowns should only contact during heavy clenching. However, a lack of occlusal contact with moderate clenching may cause supra-eruption of antagonist natural teeth. The main objective of this study was to assess changes in the occlusal contacts of posterior implant-supported single crowns with natural antagonist teeth two years after placement. The occlusal schemes of 14 patients who received 16 implant-supported single crowns in molar and premolar regions were assessed in this prospective study. Just after crown placement, at 6 months and after 2 years a silicone maxillomandibular relationship and T-scan records were obtained during the intercuspal position with light and heavy clenching, determined using near half of the maximum force and maximum force respectively. Occlusal contacts were assessed quantitatively and qualitatively in the implant-supported single crowns, contralateral tooth and adjacent tooth; the latter two were used as controls. After six months and two years, no significant variations were observed in any region of the occlusal scheme in any assessments, including silicone record or T-Scan, using light or heavy clenching, and qualitative or quantitative occlusal contact assessment. In this preliminary study, the occlusal scheme did not vary at the intercuspal position two years after placing posterior implant-supported single crowns.

Masticatory rhythm 3 months after treatment with unilateral implant-supported fixed partial prosthesis: A clinical study

STATEMENT OF PROBLEM

Whether treatment with an implant-supported fixed partial prosthesis (ISFPP) affects the masticatory rhythm in patients with unilateral posterior missing teeth is unclear.

PURPOSE

The purpose of this prospective clinical study was to determine the change in masticatory rhythm in participants with unilateral posterior missing teeth 3 months after treatment with an ISFPP and to assess whether treatment influenced the stability of the masticatory rhythm.

MATERIAL AND METHODS

Thirty participants (mean age 59 years; 17 women) with unilateral posterior missing teeth were treated with 1-, 2-, or 3-unit ISFPPs. Ten healthy individuals (mean age 36 years; 8 women) with a complete natural dentition were included in a control group. In this prospective study, each participant performed 3 masticatory assays (freestyle, unilateral right, and unilateral left) at baseline and at the 3-month follow-up. Each assay comprised 5 trials of 20 cycles masticating pieces of silicone placed in a latex bag. The time needed to complete the 20 masticatory cycles per trial was measured, and the mean masticatory frequency was calculated for each assay. Coefficients of variation were then calculated from the 5 mean values of the masticatory trials. Differences in the data at 3 months and baseline were analyzed by using the Wilcoxon or paired t tests. The control and treated groups were compared by analysis of variance or Mann-Whitney U tests (α=.05).

RESULTS

After 3 months, participants treated with ISFPPs showed an increase of 8.7% in masticatory frequency during freestyle mastication (P<.001) and an 8.0% increase during unilateral mastication on the treated side (P<.01). At baseline, the coefficient of variation of masticatory frequency on the treated side was higher in the ISFPP group than in the control group during unilateral mastication (P=.033). Three months after treatment, there was a significant reduction in the coefficient of variation during unilateral mastication on the treated side of the ISFPP group (P<.001). The treatment group also reached a masticatory frequency similar to that of the control group (75 and 78 cycles per minute, respectively).

CONCLUSIONS

Treatment with ISFPPs accelerated the masticatory rhythm of individuals with unilateral posterior missing teeth, who achieve similar rhythms to those with complete natural dentitions. The stability of the masticatory rhythm was also restored, indicating an improvement in masticatory function.

Relationship between Unilateral Posterior Crossbite and Human Static Body Posture

Background: We compared photogrammetry-assessed body posture between young adults with and without unilateral posterior crossbite (UPCB). Assessments were controlled by vision, mandibular position and sitting/standing position. In addition, we aimed to determine the relationship between UPCB laterality and the direction of body posture using photogrammetry and a static postural platform. Methods: Adults with natural dentition, with and without UPCB, were enrolled. Static body posture was assessed by photogrammetry based on horizontal acromial alignment and horizontal anterior-superior iliac spine (ASIS) alignment. Frontal photographs were taken with participants asked to open or close their eyes and hold their jaws at rest, at an intercuspal position, and at left or right lateral positions. Distribution of foot pressure was recorded using a static postural platform at different visual input and mandibular positions. General linear models with repeated measures were used to assess the effect of the various within- and between-subject factors. Results: In total, 36 adults (left UPCB = 12; Right UPCB = 6; controls = 18) participated. There were significant differences between the control and UPCB groups in horizontal alignment at the acromion (p = 0.035) and ASIS (p = 0.026) levels when controlled by visual input and mandibular position. No significant differences in horizontal alignment or foot pressure distribution were observed by laterality in the UPCB group. Conclusion: The presence of UPCB affects static body posture, but the side of crossbite is not related to the direction of effect on static body posture.

Nutritional status and masticatory function of the indigenous compared with non-indigenous people of Nayarit, Mexico

OBJECTIVE

The objective of this study was to compare the nutritional statuses and masticatory function of the non-indigenous and indigenous adult people of the state of Nayarit, Mexico.

DESIGN

Forty-two indigenous (Cora or Huichol ethnic group) and 100 non-indigenous people, all adults with natural dentition, participated in this cross-sectional study. They performed a free-style masticatory test consisting five trials of chewing silicon pieces for 20 cycles. Masticatory performance was determined by sieving the silicon particles, masticatory laterality was determined by calculating the asymmetry index, and the cycle duration was also recorded. Weight and body fat mass were measured using a portable digital weighing machine and height and body circumferences were recorded to calculate the body mass index (BMI), body fat percentage, and the waist-hip ratio. Each aspect of masticatory function and each nutritional variable were compared using T-test, analysis of variance, and Kruskal-Wallis or Mann-Whitney tests, as appropriate.

RESULTS

Body fat percentage, BMI, and waist-hip ratio were higher (P < 0.0005) in the indigenous group compared to the non-indigenous. The indigenous group had a significantly shorter stature than the non-indigenous group. Cora group had a higher BMI and higher percentage of body fat than the Huichol group (P < 0.05). No significant differences were detected between the groups for any aspect of masticatory function.

CONCLUSIONS

Indigenous people from the Nayarit, especially the Cora ethnic group, are more obese, have more total body fat, and more abdominal fat than non-indigenous people. Indigenous people show similar masticatory function.

Changes in masticatory laterality 3 months after treatment with unilateral implant-supported fixed partial prosthesis

OBJECTIVE

This study assessed changes in masticatory laterality in patients with unilateral posterior missing teeth 3 months after treatment with an implant-supported fixed partial prosthesis (ISFPP).

METHODS

Thirty patients with unilateral posterior missing teeth participated in this prospective study. They were treated with one-, two- or three-unit ISFPPs. The control group comprised 10 healthy individuals with complete natural dentition. Each participant performed masticatory assays at baseline and at 3-month follow-up, chewing pieces of silicon inside a latex bag. Masticatory laterality was determined using three different methods: assessment of the first chewing cycle, of all cycles and application of a visual analogue scale. Data were compared using the Kruskal-Wallis or the Mann-Whitney U test as appropriate.

RESULTS

Three months after treatment, a significant change in the asymmetry index towards the treated side and a significant reduction in the Unilateral Chewing Index were observed in the ISFPP group. No significant differences in masticatory laterality between groups were detected at 3-month follow-up, regardless of the method assessed.

CONCLUSION

Treatment with ISFPPs alters the masticatory laterality, moving it to the treated side and increasing the degree of bilateral chewing in patients with unilateral posterior missing teeth.

Relations of laterality and chewing sidedness in twins

OBJECTIVES

To study, whether there are associations between chewing side preference and other lateralities, whether there is a genetic origin for preferred chewing side (PCS), relations to sex, birth order and orthodontic treatment.

MATERIALS AND METHODS

The study included 113 twin pairs, 57 pairs monozygotic, 47 pairs same sex dizygotic and 9 pairs of opposite sex. The lateralities of preferred chewing side, footedness and eyedness were assessed by functional tests and handedness was checked by asking.

RESULTS

Right-handed, -footed and -eyed as separated groups, and true-right sided (combined), were evenly distributed by preferred chewing side. By contrast, left-handed, -footed, -eyed and non-right sided used more left or both sides when chewing. Birth order affected preferred chewing side among monozygotic: the first-born twin was more likely to have the preferred chewing side on the non-right, whereas second-born twins used right side. Gender, zygosity and orthodontic treatment were not statistically significant factors.

LIMITATIONS

Examination of chewing sidedness could have been done in several different ways to provide a definite result. Sample size of opposite sex twins was very small.

CONCLUSIONS

Preferred chewing side generally seemed to follow the side where other lateralities occur; however, monozygotic twins seemed to be more receptive to it. True-right sided were more evenly distributed than non-right sided by the preferred chewing side.

Do implant-supported fixed partial prostheses improve masticatory performance in patients with unilateral posterior missing teeth?

OBJECTIVES

The purpose of this study was to determine the improvement in masticatory performance and satisfaction with chewing ability in partially edentulous patients after treatment with an implant-supported fixed partial prosthesis (ISFPP).

MATERIAL AND METHODS

This prospective study included 30 patients (mean age 59 years; 17 women) with unilateral posterior missing teeth treated with one-, two- or three-unit ISFPPs and 10 healthy individuals (mean age 36 years; 8 women) with complete natural dentition to establish the normal levels of mastication. Three variables were determined at baseline and at 3-months' follow-up in all participants: masticatory performance according to the median particle size (MPS) during freestyle mastication and unilateral mastication on each side, and satisfaction with chewing ability using a visual analog scale. Paired samples t test and Kruskal-Wallis test were used for intra-group and inter-group comparisons.

RESULTS

The MPS following freestyle mastication decreased significantly at 3 months in both groups. Significant reductions of 21%, 30%, and 42% in the MPS were obtained from unilateral mastication on the treated side after treatment with 1, 2, or 3 restorative units, respectively. Three months after ISFPP, satisfaction with chewing ability improved by 40% in the treatment group.

CONCLUSIONS

Freestyle masticatory performance may improve slightly within three months of treatment with an ISFPP and may be similar to that of subjects with complete natural dentition. Patients may obtain a 21%-38% improvement in unilateral mastication on the treated side and a 26%-54% improvement in satisfaction with chewing ability.

Association between preferred chewing side and dynamic occlusal parameters

Objectives

Evaluation of dynamic occlusal parameters can help dentists to understand the association of occlusion with the preferred chewing side (PCS) and enable optimal restoration of masticatory efficiency. This study evaluated the association between PCS and dynamic occlusal parameters.

Methods

One hundred participants (50 each, right and left PCS) were included in this study. PCS was determined by the visual spot-checking method, and occlusal analysis was conducted by T Scan. Occlusal parameters evaluated included initial contact, center of force, tooth contact area, occlusal interferences, and occlusal time. Data were assessed by chi-squared test and eta correlation coefficient.

Results

Initial contact towards the PCS was observed in 68% and 70% of right and left unilateral chewers, respectively. Likewise, center of force towards the PCS was present in 72% and 66% of right and left unilateral chewers, respectively. A larger area of tooth contact was predominant towards the PCS in 70% and 72% of right and left unilateral chewers, respectively. Chi-squared analysis showed a strong positive correlation between PCS and occlusal parameters at maximum intercuspation. Eta correlation coefficients between PCS and occlusal interferences, as well as centric and eccentric occlusion, revealed negligible associations.

Conclusion

Dynamic occlusal parameters may be associated with PCS.

Reliability of a new test food to assess masticatory function

OBJECTIVE

This study assessed the reliability and validity of masticatory function assessment using a new test food, Optozeta.

DESIGN

Thirty-five adults participated in the cross-sectional clinical part of the study; ten of them performed a retest. They performed two free-style masticatory tests consisting of five trials of 20 cycles each chewing three pieces of Optosil or Optozeta placed in a latex bag. Optozeta was created by mixing 50% Optosil with 50% of Zetalabor. Masticatory performance, masticatory laterality and chewing rate were assessed. Reliability and construct validity were assessed using the intraclass correlation coefficient (ICC) and Spearman correlations, respectively.

RESULTS

Higher ICC values were observed for each aspect of masticatory function as assessed using Optozeta compared with Optosil. All the participants showed a lower median particle size value using Optozeta than Optosil. For each masticatory parameter, a high correlation was observed between using Optosil or Optozeta.

CONCLUSIONS

Optozeta seems to have good construct validity and appears to be more reliable than Optosil as a test food to assess masticatory function.

Does the habitual mastication side impact jaw muscle activity?

OBJECTIVE

To compare electrical activity in the anterior temporal and masseter muscles on the habitual (HMS) and non-habitual mastication side (NHMS), during mastication and in the mandibular postural position. In addition, the increase in electrical activity during mastication was assessed for the HMS and NHMS, analysing both working (WSM) and non-working side during mastication (NWSM).

METHODS

A total of 28 healthy women (18-32 years) participated in the study. They were submitted to Kazazoglu's test to identify the HMS. Bioresearch 'Bio EMG' software and bipolar surface electrodes were used in the exams. The exams were conducted in the postural position and during the unilateral mastication of raisins, on both the HMS and NHMS. The working and non-working side on HMS and NHMS were assessed separately. The obtained data were then statistically analysed with SPSS 20.0, using the Paired Samples Test at a significance level of 95%.

RESULTS

The differences in the average EMG values between HMS and NHMS were not statistically significant in the postural position (Temporal p=0.2; Masseter p=0.4) or during mastication (Temporal WSM p=0.8; Temporal NWSM p=0.8; Masseter WSM p=0.6; Masseter NWSM p=0.2). Differences in the increase in electrical activity between the masseter and temporal muscles occurred on the working side, on the HMS and NHMS (p=0.0), but not on the non-working side: HMS (p=0.9) and NHMS (p=0.3). The increase in electrical activity was about 35% higher in the masseter than in the temporal muscle.

CONCLUSIONS

Mastication side preference does not significantly impact electrical activity of the anterior temporal and masseter muscles during mastication or in postural position.

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 force.

Assessment of swallowing and masticatory performance in obturator wearers: a clinical study

PURPOSE

To assess function by identifying changes in swallowing and masticatory performance in maxillary obturator prosthesis wearers.

MATERIALS AND METHODS

Sixty subjects were recruited for the study, of which 20 were obturator wearers, 20 were completely dentulous and 20 had removable partial/complete dentures with similar Eichner's Index. Swallowing ability was evaluated with and without obturator using the "Water Drinking Test"; Masticatory performance was evaluated with the Sieve test; and maximum occlusal force was recorded with the help of a digital bite sensor. The data was analyzed using the Statistical Package for Social Science version 15.0 with a confidence level at 95%.

RESULTS

Profile, behavior of drinking and time taken to drink were significantly improved (P<.001) in subjects after wearing obturator. Masticatory performance was not significantly different (P=.252) in obturator wearer when compared with dentulous or removable partial/complete denture wearer, but significantly (P<.001) high inter group difference in maximum occlusal force existed. Correlation between masticatory performance and maximum occlusal force was not significant (P=.124).

CONCLUSION

Swallowing ability was significantly improved after wearing obturator but masticatory performance was not significantly different from those having similar occlusal support zone in their dentition.