Search

Background/purpose While scan delay may affect the measurements of an occlusal pressure-sensitive film, Dental Prescale II (DPS2), the duration of scan delay was rarely reported in previous studies. This study aimed to clarify the effect of scan delay on DPS2 measurements. Materials and methods Two experiments were performed to clarify the effect of 0- to 10-min scan delay after DPS2 force registration. In both experiments, 11 loads were applied separately on a DPS2 film at 1-min interval between loads. Scanning was performed immediately after the 11th load in the 1-scan experiment and immediately after each load in the 11-scan experiment. A 300-N load was applied with a universal testing machine on 10 DPS2 films in each experiment and the DPS2 film was scanned with Bite Force Analyzer. Load measured, contact area, mean pressure, and maximum pressure were reported. ANOVA and Scheffe test were performed to compare the effect of number of scans and delay scan duration on these measurements with the critical value set at P ≤ 0.05. Results Number of scans had no significant effect on the four measurements studied. However, all measurements, except contact area, were significantly affected by scan delay; the longer the scan delay, the greater the increase in measurements. The load measured showed a rapid increase (13%) in the first 2 min, followed by a gradual increase from 2 min to 10 min (10%). Conclusion Scan delay does affect DPS2 measurements, and it is important to standardize and report scan delay duration in clinical studies.

The aim of the current study was to document the long-term clinical results of the use of two prosthetic techniques for the rehabilitation of completely edentulous maxillae according to the “All-on-Four” concept: Fixed, screw-retained prosthesis mounted on a chrome-molybdenum framework with (1) metal-ceramic veneers and (2) Acrylic prosthesis with acrylic resin prosthetic teeth. A total of 34 patients were assigned to subgroups according to their own preference of the superstructure type (ceramics [n: 17] or acrylic resin [n: 17]). Prosthetic complications, marginal bone loss, plaque accumulation, bleeding on probing, bite force and oral-health-related quality of life were assessed over a period of 6 years. Marginal bone loss around implants of the ceramic group remained well within the limits for ‘success’, as defined by the 2007 Pisa consensus over the time (1.43 ± 0.35 mm). However, marginal bone loss was significantly more pronounced around the implants in the acrylic group (2.15 ± 0.30) and the difference between two groups was statistically significant (p: 0.00). Bleeding on probing and plaque accumulation showed also positive correlation with marginal bone loss. Both acrylic and ceramic suprastructures appeared to be equivalent after 6 years; however, ceramic suprastructures revealed superior clinical results in terms of bone loss and plaque accumulation. Current study determines the long-term clinical outcomes of different prosthetic management alternatives in All-on-Four and aids to increase dental professionals’ ability to meet the patients’ expectations.

Decreases in masticatory function are believed to be related to the development of cardiovascular disease (CVD) through inappropriate nutritional intake. This study focused on maximum bite force (MBF), which is an objective, quantitative index of masticatory function, and its association with the development of CVD (stroke and coronary heart disease) was investigated. The subjects were 1547 participants of the Suita study with no history of CVD who underwent medical and dental health examinations between June 2008 and June 2013. In addition to undergoing a basic physical examination at baseline, their MBF was measured. They subsequently underwent follow-up surveys for the development of CVD (mean follow-up, 3.5 years). The association between baseline MBF and the development of CVD was investigated by multivariate adjustment using a Cox proportional hazards model. CVD developed in 32 subjects during follow-up. The trend test showed a significant association between baseline MBF and CVD in a model that combined men and women. When analysed by sex, the trend test found a significant association between baseline MBF and CVD in women. Low MBF, which is an objective and quantitative index of masticatory function, may be a risk factor for the development of CVD.

Objectives: Many authors’ have advocated a minimum of two implants to support a mandibular overdenture, but financial restraints specifically among the geriatric population in developing countries made this treatment plan economically difficult. Hence, this study was planned to assess the symphyseal (midline) single implant-assisted complete overdenture for patient satisfaction and masticatory performance. Materials and Methods: In this clinical study, 12 edentulous first-time denture wearers underwent placement of a single implant in the mandibular symphyseal region. After 1 week, new complete dentures were fabricated and delivered to the patients. Post 3 months, the denture was fixed with a nylon cap-ball attachment to the anchor implant. Patients were questioned about comparison in the level of satisfaction and complaint before loading the implant (control group) and after 1 week, 1 month, and 3 months. The implant-assisted overdenture was fabricated with the help of a questionnaire. Masticatory performance was calculated with the help of a bite force measuring device at the same time intervals. SPSS 17.0 statistical software was used to analyze the data. Results: It was found that single implant anchorage of the mandibular complete denture resulted in a significant increase (P < 0.05) in patient's subjective satisfaction and a decrease (P < 0.05) in complaints at the end of 3 months. There was a significant (P < 0.01) increase in bite force in implant overdenture after 3 months (5.459 kgf) as compared to that of the complete denture (3.406 kgf). Conclusion: Single implant-assisted overdenture can be an appropriate treatment modality to treat edentulousness in the geriatric population. It insinuates the remarkable improvement of prosthesis function and oral comfort with minor surgical procedures.

Aim and Objectives: This in vivo cross-sectional study aimed to measure and correlate the average and maximum bite forces between cleft and noncleft individuals. Materials and Methods: The study was conducted on thirty cleft and thirty noncleft lip and palate patients who were belonging to the age group of 14–30 years with unrepaired unilateral cleft lip and palate under treatment at the Craniofacial Center, Yenepoya Dental College, Mangalore, and G. S. R Craniofacial Center, Hyderabad, India. Dental Prescale® sheet was used to record the bite force of the patients and the test sheet was scanned with an Epson v330 color HD photo scanner, and the bite force was evaluated by an FDP 8010 analyzing system. The data were analyzed statistically by the Student's data t-test. Results: The control group had a statistically significantly higher mean pressed area on the left side (P = 0.034), maximum pressure on the left side (P < 0.001), mean maximum pressure on the right side (P = 0.024), and mean average pressure on the left side (P = 0.038). There was no statistically significant difference in the mean pressed area on the right side (P = 0.569) and average pressure on the right side of the control and study groups (P = 0.358). Conclusions: There was a statistically significant difference in the mean maximum pressure (P = 0.001) and average pressure (P = 0.039) among cleft lip and palate patients when compared with that of the control group. There was no significant difference between male and female subjects of both the groups.

Background: Muscle fatigue or the inability to maintain muscle strength is a protective mechanism to prevent muscle injury. Phototherapy or low-level laser therapy (LLLT) and therapeutic ultrasound are non-invasive and non-pharmacological forms of treatment modalities that have demonstrated effective and affirmative results when used to prevent muscle fatigue. Aim: The study evaluated the effect of phototherapy and therapeutic ultrasound in reducing muscle fatigue when administered before the induction of fatigue. Methodology: The study design was a blind, randomized, and sham-controlled clinical trial on laser and therapeutic ultrasound. The study sample consisted of 100 healthy young participants randomly allocated to four different groups of lasers, sham laser, therapeutic ultrasound, and sham ultrasound. All the individuals were subjected to clinical examination to record the bite force by the bite force dynamometer, maximum interincisal distance (MID) by using digital vernier calipers, and muscle fatigue by using EMG Retrainer's Device. The laser and therapeutic ultrasound were given on the masseter and anterior temporalis muscle on both sides and both sham groups were submitted to the same procedure but with the devices in the switch-off mode. All the individuals were instructed to chew two pieces of gum (one on each side) for 6 min to induce muscle fatigue and MID, the bite force and muscle fatigue were re-evaluated. Results: Statistically significant improvement was observed between the pre-and post-bite force, MID, and muscle fatigue in both the laser and Therapeutic ultrasound group as compared to the sham control groups with the P-value equal to 0.000. No, statistically significant difference was observed in the improvement of the muscle fatigue when both the treatment groups, i.e., laser and therapeutic ultrasound were compared with a P value >0.05. Conclusion: Muscle fatigue can be effectively reduced if any one of the physical modalities, either laser or therapeutic ultrasound is administered before the long-duration treatments; enabling administration of treatment comfortably and effectively in one appointment.

Orofacial pain or tenderness is a primary symptom associated with temporomandibular joint (TMJ) disorders (TMDs). To understand the pathological mechanisms underlying TMDs, several mouse models have been developed, including mechanical stimulus-induced TMD and genetic mouse models. However, a lack of feasible approaches for assessing TMD-related nociceptive behaviours in the orofacial region of mice has hindered the in-depth study of TMD-associated mechanisms. This study aimed to explore modifications of three existing methods to analyse nociceptive behaviours using two TMD mouse models: (1) mechanical allodynia was tested using von Frey filaments in the mouse TMJ region by placing mice in specially designed chambers; (2) bite force was measured using the Economical Load and Force (ELF) system; and (3) spontaneous feeding behaviour tests, including eating duration and frequency, were analysed using the Laboratory Animal Behaviour Observation Registration and Analysis System (LABORAS). We successfully assessed changes in nociceptive behaviours in two TMD mouse models, a unilateral anterior crossbite (UAC)-induced TMD mouse model and a β-catenin conditional activation mouse model. We found that the UAC model and β-catenin conditional activation mouse model were significantly associated with signs of increased mechanical allodynia, lower bite force, and decreased spontaneous feeding behaviour, indicating manifestations of TMD. These behavioural changes were consistent with the cartilage degradation phenotype observed in these mouse models. Our studies have shown reliable methods to analyse nociceptive behaviours in mice and may indicate that these methods are valid to assess signs of TMD in mice.

Osteoarthrosis is a disorder of synovial joints, resulting from destruction of the cartilage and subchondral bone. The present study is aimed to investigate the molar bite force, thickness and efficiency of the masseter and temporalis muscles of subjects with osteoarthrosis. A total of forty-eight subjects participated in the study. They were distributed into two groups: with osteoarthrosis (n=24) and asymptomatic controls (n=24). Subjects were analyzed on the basis of maximal molar bite force (right and left side), thickness (mandibular rest and dental clenching in maximal voluntary contraction) and electromyographic activity of masticatory cycles through the linear envelope integral in habitual (raisins and peanuts) and non-habitual (Parafilm M) chewing of the masseter and temporalis muscles. All the data were analyzed statistically using t-test with a significance level of p≤0.05. There was no difference between groups in maximal molar bite force, muscle thickness and non-habitual chewing. Differences were found on the raisins (p=0.02) and peanuts (p=0.05) chewing for right temporal muscle, with reduced masticatory muscle efficiency in osteoarthrosis subjects. This study showed that osteoarthrosis induces negative changes in habitual chewing, highlighting the efficiency of the right temporalis muscles. The greater temporal muscle activity in subjects with osteoarthrosis may compromise chewing and consequently the nutritional status of adult subjects.

Background The aim of this study was to analyse the stomatognathic system of adult women with chronic allergic rhinitis by means of molar bite force and electromyographic activity of the masseter and temporalis muscles. Material and Methods A total of 26 subjects were screened and divided into two distinct groups: chronic allergic rhinitis group (n = 13) and healthy control group (n = 13). Subjects were assessed by maximal molar bite force (right and left) and normalized electromyographic activity of mandibular tasks (rest, right and left laterality, protrusion and maximal voluntary contraction). Data were submitted to Student's t test (p< .05). Results There was significant difference in right (p = .03) and left (p = .04) maximal molar bite force with force reduction in the chronic allergic rhinitis group. There was significant difference in normalized electromyographic activity in maximal voluntary contraction in the right (p =.01) and left (p = .01) temporalis muscles, with increased electromyographic activity in the masticatory muscles for the chronic allergic rhinitis group. Conclusions The results suggest that chronic allergic rhinitis in adult women promoted negative changes in the electromyographic activity of temporalis muscles in maximal voluntary contraction and maximal molar bite force. Key words:Rhinitis, occlusal force, electromyography, masticatory muscles.

Jaw-muscle architecture is a key determinant of jaw movements and bite force. While static length-force and force-velocity relationships are well documented in mammals, architecture dynamics of the chewing muscles and their impact on muscle performance are largely unknown. We provide novel data on how fiber architecture of the superficial anterior temporalis (SAT) varies dynamically during naturalistic feeding in tufted capuchins (Sapajus apella). We collected data on architecture dynamics (changes in muscle shape or the architectural gear ratio) during the gape cycle while subjects fed on foods of different mechanical properties. Architecture of the SAT varied with phases of the gape cycle, but gape distance accounted for the majority of dynamic changes in architecture. In addition, lower gear ratios (low muscle velocity relative to fascicle velocity) were observed when animals chewed on more mechanically resistant foods. At lower gear ratios, fibers rotated less during shortening resulting in smaller pinnation angles, a configuration that favors increased force production. Our results suggest that architectural dynamics may influence jaw-muscle performance by enabling the production of higher bite forces during the occlusal phase of the gape cycle and while processing mechanically challenging foods.

Objectives This proof‐of‐principle, single‐center, randomized, examiner‐blind, crossover study compared two experimental polyvinyl acetate (PVA)‐based denture adhesives (Test Adhesives 1 and 2) with a marketed reference polymethyl vinyl ether/maleic anhydride (PMV/MA)‐based adhesive and no adhesive using incisal bite force area over baseline over 12 hr (AOB0–12) in participants with an at least moderately well‐fitting complete maxillary denture. Previous in vitro studies suggested the experimental denture adhesives provided superior performance. Materials and Methods Participants were randomized to a treatment sequence such that each received each treatment once. Prior to treatment application (baseline) and at 0.5, 1, 3, 6, 9, and 12 hr following the application, participants bit on a force transducer until their maxillary denture dislodged. Between‐treatment differences in AOB0–12 were analyzed using analysis of covariance. For study validity, the reference adhesive was compared with no adhesive. Participants were asked to rate sensory experiences and ease of denture removal. Results Twenty‐three participants were included in the modified intent‐to‐treat population. Although Test Adhesives 1 and 2 had a higher mean AOB0–12 than no adhesive, differences were not statistically significant. No statistically significant difference was also found between the reference adhesive and no adhesive; hence, study validity was not attained. Participants did not report any clear differences between the test or reference adhesives in terms of taste or feel; however, dentures were easier to remove with the test adhesives versus reference. No treatment‐related adverse events were reported. Conclusion Neither the experimental PVA‐based denture adhesives nor the PMV/MA‐based reference product demonstrated a statistically significant difference in incisal bite force AOB0‐12 compared with no adhesive. The reasons for these unexpected results is unclear; they suggest that findings of in vitro tests for denture adhesive performance are not always translated to in vivo performance (http://Clinicaltrials.gov: NCT02937870).

Purpose: The purpose of this study was to observe the impact of oral oncological treatment, including the recovery of several tongue functions (force, mobility, and sensory functions), and to determine the influence of these functions on masticatory performance. Materials and methods: Masticatory performance and tongue force, mobility, and sensory functions were determined in 123 patients with oral cavity cancer. The assessments were performed 4 weeks before treatment and 4 to 6 weeks, 6 months, 1 year, and 5 years after treatment. Generalized estimation equations and mixed model analyses were performed, correcting for previously identified factors in the same population. Results: A significant deterioration in tongue mobility and sensory function was observed in patients with mandible and tongue and/or floor-of-mouth tumors. Better tongue force and sensory function (thermal and tactile) positively influenced masticatory performance, and this effect was stronger where fewer occlusal units were present. The effect of both the tongue force and maximum bite force was weaker in dentate patients in comparison with patients with full dentures. A web-based application was developed to enable readers to explore our results and provide insight into the coherence between the found factors in the mixed model. Conclusions: Tongue function deteriorates after oral oncological treatment, without statistically significant recovery. Adequate bite and tongue forces are especially important for patients with a poor prosthetic state. Patients with sensory tongue function deficits especially benefit from the presence of more occluding pairs.

Aim To compare and evaluate biting force and chewing efficiency of all-on-four treatment concept, implant-supported overdenture, and conventional complete denture. Settings and design Invivo - comparative study. Materials and methods A total of 12 edentulous patients were included in the study and conventional complete dentures were fabricated. Patients were divided into two groups. In Group 1, complete dentures were replaced with implant-supported overdenture, and in Group 2, complete dentures were replaced with hybrid denture supported by all-on-four treatment concept. The biting force was assessed using a bite force sensor and electromyographic recordings were made by electromyogram for masticatory muscles when chewing three different consistencies of foods. Statistical analysis used The data was statistically analyzed using software SPSS version 22.0. Paired t-test was used for intra-group comparison and unpaired t-test was used for intergroup comparison. Results The difference in biting force and chewing efficiency for all-on-four treatment concept was statistically significant for overdenture and complete denture. The highest biting force and chewing efficiency were observed for all-on-four treatment concept, followed by implant-supported overdenture and complete denture. Conclusion The study concluded that the completely edentulous individuals with atrophic posterior alveolar ridges can be rehabilitated successfully with improved biting force and chewing efficiency by All-on-four treatment concept.

Aim: The narrowing of the mandible during opening and protrusion movements is defined as median mandibular flexure (MMF). MMF is caused by the attachment of mandibular muscles; therefore, it can be assumed that a greater amount of maximum occlusal force (MOF) may cause more flexion and could affect the survival of dental and implant restorations. The purpose of this study was to evaluate any relationship between MOF and MMF in a sample of adults. Settings and Design: In vivo – comparative study. Materials and Methods: In this descriptive, cross-sectional, nondirectional study, a sample of 90 volunteers were recruited (45 men and 45 women). MOF was measured by applying the strain gauge receptor to the first molar region, and MMF was measured by calculating the variation in the intermolar distance by a digital caliper with an accuracy of 0.01 mm using an impression and resulted in the stone cast during the maximum opening and closed-jaw positions. The body mass index (BMI) also was calculated. Statistical Analysis: Data were analyzed using the SPSS software (version 23) inferential and descriptive statistics, linear regression, and Pearson correlation coefficient. P < 0.05 was considered statistically significant. Results: There was no statistically significant relationship between MOF and MMF (P = 0.78), but there was a significant association between MOF and BMI (P < 0.001, r = 0.475) and gender. Conclusion: Although MOF and MMF are both important and effective factors in the success of prosthetic restorations, one cannot be expected by the other and both should be considered in the treatment plan separately.

Purpose: To determine the Maximum voluntary bite force among patients having different personality traits. Methods: In total, 323 patients were given the big-five inventory (BFI) questionnaire to fill and allotted to the various personality traits. The patients in the Agreeableness (n = 62) and Neuroticism traits (n = 62) were included in the study. They were categorized into groups as Group 1a – Neuroticism male (41 patients) and Group 1b – Neuroticism Female (21 patients) and Group 2a – Agreeableness male (26 patients) and Group 2b – Agreeableness female (36 patients). Highest value of the maximal voluntary bite force (MVBF) was recorded using FlexiForce sensor (B 201) (Tekscan, USA). The statistical data were analyzed by independent t-test (P < 0.05). Results: The mean bite force values for Neuroticism male was 778.66 N, Agreeableness male was 699 N, Neuroticism female was 686.24 N, and for Agreeableness female was 565.47 N. Statistically significant differences in the bite forces between the male and female groups of both the groups with the males showing significantly higher bite force values in both groups was seen. Also, the bite force in Neuroticism male was significantly higher than Agreeableness male and bite force in Neuroticism female was higher than Agreeableness female. Conclusion: In this study, the highest bite force was seen in Neuroticism males. Additionally, this study infers that personality has significant influence on the quantum of bite force. Thus, personality assessment of the patient can assist the clinician in planning the appropriate treatment.

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pain in masticatory muscles is one of the most frequent symptoms in patients with temporomandibular disorders (TMD) and can lead to changes in the patterns of neuromuscular activity of masticatory muscles and decrease in bite force. This study assesses the effects of three eight-week exercise programs on pain intensity, neuromuscular activation, and bite force of masticatory muscles in patients with TMD. Forty-five patients were divided into three groups: a therapeutic exercise program (G1), a therapeutic and aerobic exercise program (G2), and an aerobic exercise program (G3). The masticatory muscles’ pain was evaluated using the numeric pain rating scale (NPRS), surface electromyographic (sEMG) activity of the masseter was recorded during maximum voluntary contraction and at rest, and bite force was evaluated using a dynamometer. These parameters were evaluated twice at baseline (A01/A02), at the end of the eight-week intervention period (A1), and 8–12 weeks after the end of the intervention (A2). After intervention, G2 showed the best results, with a significantly decrease in masticatory muscles’ pain and increase in bite force. These results suggest that interventions to reduce pain in patients with TMD should be multimodal. info:eu-repo/semantics/publishedVersion

Background: Digital bite measurement systems such as the T-Scan III allow for the computerized measurement of occlusal force distribution. This study aimed to establish the relationship between dentofacial vertical pattern and bite force distribution among children in late mixed dentition. Materials and Methods: In total, 86 children (45 male, 41 female) aged between 9 and 11 years with short (n = 28), medium (n = 28), and long (n = 30) facial heights were included in this study. The height, weight, age, and gender were recorded. Occlusal bite force distribution and time of occlusal cycle were recorded using a T-Scan III device (Tekscan Corp. Boston, MA, USA). The bite force distribution was compared among facial types using a One-Way ANOVA and post hoc test, a linear regression model with time of occlusion as dependent variable was developed. Results: No significant differences were observed in occlusion time between genders. Children with long facial height had a significantly lower anterior bite force distribution (p &lt, 0.05) and significantly higher posterior bite force distribution (p &lt, 0.05) than those with average or short facial height. Age, gender, height, and weight had no significant association with time of the occlusal cycle. Conclusion: Children with an increased vertical facial height have a more posterior distribution of force than children with average or short facial heights in the late mixed dentition.

Purpose: to assess the bite force in people with Parkinson’s disease and correlate it with age, sex, stage and time of the disease, dentures use, presence of temporomandibular disorder, side of symptom onset, and masticatory preference. Methods: the Research Diagnostic Criteria for Temporomandibular Disorders and the Hoehn & Yahr Parkinson’s disease scale were used, and the participants’ oral cavity was clinically examined. Then, the bite force was measured with an analog dynamometer, whose bar was adapted for mouth grip. The bite force results and their correlation with the variables were analyzed with the independent t-test (p

Simple Summary The cranial structure is highly variable among mammals and thought to reflect specializations for feeding and echolocation in bats. However, recent analyses of skull structure, feeding behavior and bite force across a wide range of bats suggest that correlations between morphology, performance, and ecology are not as delineated as previously thought. For example, most of the variations in bite force in insectivorous bats have been explained by differences in body size rather than specific cranial traits. We tested several relationships associated with the cranium to ascertain predictors of bite force in different bat species based on in vivo measurements from the Colombian tropical dry forests and museum specimens. Our data show that skull size had a significant contribution to bite force for beetle-eating bats, such as Noctilio albiventris, Molossus molossus, M. coibensis, and Molossops temminckii. Cranial traits and the combined action of the jaw morphology generate a biomechanical comparative advantage that allows these species to feed on “hard” prey, supporting the hypothesis that skull morphology, bite force, and diet are linked in insectivorous bats. Abstract In Neotropical bats, studies on bite force have focused mainly on differences in trophic ecology, and little is known about whether factors other than body size generate interspecific differences in bite force amongst insectivorous bats and, consequently, in their diets. We tested if bite force is related to skull morphology and also to diet in an assemblage of Neotropical insectivorous bats from tropical dry forests in the inter-Andean central valley in Colombia. It is predicted that the preference of prey types among insectivorous species is based on bite force and cranial characteristics. We also evaluated whether skull morphology varies depending on the species and sex. Cranial measurements and correlations between morphological variation and bite force were examined for 10 insectivorous bat species. We calculated the size-independent mechanical advantage for the mandibular (jaw) lever system. In all species, bite force increased with length of the skull and the jaw more than other cranial measurements. Obligate insectivorous species were morphologically different from the omnivorous Noctilio albiventris, which feeds primarily on insects, but also consumes fish and fruits. Our results show that bite force and skull morphology are closely linked to diets in Neotropical insectivorous bats and, consequently, these traits are key to the interactions within the assemblage and with their prey.

Background: Removable partial dentures are a frequently used prosthetic treatment in the elderly population, but different types or RPDs might guarantee different chewing capabilities. In many studies, the relationship between chewing and aging has been reported and it has been shown that efficient chewing can improve the overall quality of life. Objectives: In the present study, the relationship between maximum bite force (MBF) and RPDs was studied. A relationship between the body mass index (BMI) and the type of prosthesis was also analyzed. Methods: 240 elderly patients, 120 males and 120 females, with bilateral posterior edentulism (class 1 of Kennedy classification) who had been wearing an RPD for at least a year, were recruited. Patients were divided into two groups: Group 1: male (n = 60) and female (n = 60) patients with bilateral edentulous areas located posterior to the remaining natural teeth and natural teeth in the opposite dental arch. Group 2: male (n = 60) and female (n = 60) patients with maxillary and mandibular bilateral edentulous areas located posterior to the remaining natural teeth. Their Body Mass Index (BMI) and Maximum bite force (MBF) were measured and compared according to the material and design of their RPD. Results: In both Groups, patients wearing cobalt-chrome alloy RPDs (Co-Cr-RPD) (Group 1: 20.25 ± 6.7 MBF, p &lt, 0.001, Group 2: 16.0 ± 5.7 MBF, p &lt, 0.001) had an increased MBF when compared to polymethylmethacrylate RPD (PMMA-RPD) (Group 1: 12.9 ± 3.36 MBF, Group 2: 10.4 + 2.8 MBF), and Valplast RPD (V-RPD) (Group 1: 14.3 ± 4.7 MBF, Group 2: 11.3 ± 3.4 MBF) users. There were no significant differences in bite force between patients wearing PMMA-RPD and V- RPD in both Groups. Patients in Group 2 showed a lower MBF than those in Group 1 (Group 1: 16.05 ± 6.13 MBF, Group 2: 12.6 ± 4.84 MBF, p &lt, 0.001). Conclusions: A reduction in chewing force can lead to choosing softer foods for nutrition, which can lead to an increase in BMI. Our results show that only CoCr-RPD wearers were able to chew consistent food, whereas PMMA- RPD and V-RPD, due to the properties of the materials, their instability, and the possibility of causing pain during mastication, determined a limitation in the choice of food for many of the participants.

The outcome evaluation method presented in this case study, including Axes I and II findings combined with the results of quantitative bite force and EMG measurements, provides a good tool for proper evaluation of the effect of BoNT‐A on patients with myofascial orofacial pain and changes in jaw muscle function.

Objective. To explore the clinical effect of root canal therapy combined with full crown restoration in patients with cracked teeth and chronic pulpitis. Methods. From May 2018 to June 2020, 87 patients with cracked teeth and chronic pulpitis in our hospital were selected; the patients were randomly divided into the control group and the research group by random number method. The control group only used root canal therapy; the research group used root canal therapy combined with full crown restoration. The therapeutic effect, levels of inflammatory factors, chewing function, periodontal index, complications, and quality of life were compared between the two groups. Results. The total effective rate of the research group (97.78%) was better than the total effective rate of the control group (85.71%) ( P < 0.05 ). Compared with before treatment, the serum levels of interleukin-1β (IL-1β), IL-6, and C-reactive protein (CRP) of the two groups of patients decreased after treatment. After treatment, compared with the control group, the serum levels of IL-1β, IL-6, and CRP in the research group decreased ( P < 0.05 ). Compared with before treatment, the bite force of teeth and chewing efficiency of the two groups of patients increased after treatment. After treatment, compared with the control group, the bite force of teeth and chewing efficiency of the research group increased ( P < 0.05 ). Compared with before treatment, the plaque index (PLI), probing depth (PD), gingival sulcus bleeding index (BI), and gingival index (GI) of the two groups of patients decreased after treatment. After treatment, compared with the control group, the PLI, PD, BI, and GI of the research group decreased ( P < 0.05 ). The total incidence of complications in the research group was (11.11%), and the total incidence of complications in the control group was (16.67%); there was no significant difference between the two groups ( P > 0.05 ). After treatment, compared with the control group, the quality of life scores of the patients in the research group were reduced ( P < 0.05 ). Conclusion. Root canal therapy and full crown restoration have a definite curative effect in patients with cracked teeth and chronic pulpitis, which can improve the inflammatory response, restore chewing function, maintain periodontal health, improve the quality of life, and do not increase the incidence of complications, so it has good application value.

Numerous anthropological studies have been aimed at estimating jaw-adductor muscle forces, which, in turn, are used to estimate bite force. While primate jaw adductors show considerable intra- and intermuscular heterogeneity in fibre types, studies generally model jaw-muscle forces by treating the jaw adductors as either homogeneously slow or homogeneously fast muscles. Here, we provide a novel extension of such studies by integrating fibre architecture, fibre types and fibre-specific tensions to estimate maximum muscle forces in the masseter and temporalis of five anthropoid primates:Sapajus apella(N= 3),Cercocebus atys(N= 4),Macaca fascicularis(N= 3),Gorilla gorilla(N= 1) andPan troglodytes(N= 2). We calculated maximum muscle forces by proportionally adjusting muscle physiological cross-sectional areas by their fibre types and associated specific tensions. Our results show that the jaw adductors of our sample ubiquitously express MHC α-cardiac, which has low specific tension, and hybrid fibres. We find that treating the jaw adductors as either homogeneously slow or fast muscles potentially overestimates average maximum muscle forces by as much as approximately 44%. Including fibre types and their specific tensions is thus likely to improve jaw-muscle and bite force estimates in primates.

Background Measuring mammals’ bite force in laboratory conditions is not a simple task, let alone on wild medium-sized mammals in the field. Thus, morphometric-proxies are usually used to infer morphofunctional properties of musculoskeletal features. For instance, the study of bite force-indexes suggests that different capacities to crack food items reduce the competition between coexistent collared and white-lipped peccaries (Pecari tajacu and Tayassu pecari). The presence of exotic feral hogs (Sus scrofa) in peccaries’ endemic areas gives rise to new ecological interactions between them. An example is the Brazilian Pantanal wetland, where ecomorphological mechanisms may play a role in their ecological relations. Taking this scenario as a case of study, we aimed to verify if the morphometric-proxies are de facto reliable tools, by comparing bite forces-indexes with the in vivo bite forces of these species. Methods We captured 21 collared and white-lipped peccaries and feral hogs in the Brazilian Pantanal to assess their bite force at first molar. The Bite Force Measuring Tube (BiTu) is a robust and simple mechanical device designed to be used in field conditions. Only 11 individuals successfully bit the BiTu before being released. Their body measurements were compared and correlated with their bite force. The in vivo bite forces were compared with bite force-indexes of two papers based on independent morphometric methods and datasets: Sicuro & Oliveira (2002) used classic morphometrics to infer the bite forces of these three species in the Brazilian Pantanal, and Hendges et al. (2019) used geometric morphometrics to compare bite forces-indexes and feeding habits of the extant peccary species. The results of all species were standardized (Z-curves) according to each method. Doing so, we obtained comparable dimensionless comparable values but maintaining the differences between them. Results The morphometric-proxies-based studies presented similar results: collared peccaries present weaker bites than white-lipped peccaries and feral hogs, while these two species presented no significant differences in their bite force-indexes. The in vivo bite force results suggest the same relations predicted by the morphometric models, including the high variation among the feral hogs. We found a significant correlation between the individuals’ weight (kg) and their actual bite force (N) but no significant correlations with the head length. Conclusions The BiTu proved to be a functional and low-cost tool to measure bite force in field conditions. The in vivo results presented a good correspondence with the predictions based on morphometric-proxies by Sicuro & Oliveira (2002) and Hendges et al. (2019). The results denote that these studies succeed in capturing the biomechanical signal of the three species’ skull-jaw systems. This empirical validation confirms that these morphometric-proxies analyses are reliable methods to ecomorphological and evolutionary inferences.

Dental microwear texture analysis (DMTA) is widely used for diet inferences in extant and extinct vertebrates. Often, a reference tooth position is analysed in extant specimens, while isolated teeth are lumped together in fossil datasets. It is therefore important to test whether dental microwear texture (DMT) is tooth position specific and, if so, what causes the differences in wear. Here, we present results from controlled feeding experiments with 72 guinea pigs, which received either fresh or dried natural plant diets of different phytolith content (lucerne, grass, bamboo) or pelleted diets with and without mineral abrasives (frequently encountered by herbivorous mammals in natural habitats). We tested for gradients in dental microwear texture along the upper cheek tooth row. Regardless of abrasive content, guinea pigs on pelleted diets displayed an increase in surface roughness along the tooth row, indicating that posterior tooth positions experience more wear compared with anterior teeth. Guinea pigs feedings on plants of low phytolith content and low abrasiveness (fresh and dry lucerne, fresh grass) showed almost no DMT differences between tooth positions, while individuals feeding on more abrasive plants (dry grass, fresh and dry bamboo) showed a gradient of decreasing surface roughness along the tooth row. We suggest that plant feeding involves continuous intake and comminution by grinding, resulting in posterior tooth positions mainly processing food already partly comminuted and moistened. Pelleted diets require crushing, which exerts higher loads, especially on posterior tooth positions, where bite forces are highest. These differences in chewing behaviour result in opposing wear gradients for plant versus pelleted diets.

BackgroundBite marks attributed to adultTyrannosaurus rexhave been subject to numerous studies. However, few bite marks attributed toT. rexhave been traced to juveniles, leaving considerable gaps in understanding ontogenetic changes in bite mechanics and force, and the paleoecological role of juvenile tyrannosaurs in the late Cretaceous.MethodsHere we present bite force estimates for a juvenileTyrannosaurus rexbased on mechanical tests designed to replicate bite marks previously attributed to aT. rexof approximately 13 years old. A maxillary tooth of the juvenileTyrannosaurusspecimen BMR P2002.4.1 was digitized, replicated in dental grade cobalt chromium alloy, and mounted to an electromechanical testing system. The tooth was then pressed into bovine long bones in various locations with differing cortical bone thicknesses at varying speeds for a total of 17 trials. Forces required to replicate punctures were recorded and puncture dimensions were measured.ResultsOur experimentally derived linear models suggest bite forces up to 5,641.19 N from cortical bone thickness estimated from puncture marks on anEdmontosaurusand a juvenileTyrannosaurus. These findings are slightly higher than previously estimated bite forces for a juvenileTyrannosaurus rexof approximately the same size as BMR P2002.4.1 but fall within the expected range when compared to estimates of adultT. rex.DiscussionThe results of this study offer further insight into the role of juvenile tyrannosaurs in late Cretaceous ecosystems. Furthermore, we discuss the implications for feeding mechanisms, feeding behaviors, and ontogenetic niche partitioning.

Aim: Temporomandibular disorders (TMD) refer to functional disorders of the masticatory system, temporomandibular joint (TMJ) and masticatory muscles. The main objective of this study was to determine whether and to what extent temporomandibular disorders (TMD) affect the maximum bite force (MBF). Methods: The present study included subjects with and without temporomandibular disorder. The presence of TMD was assessed by means of the Helkimo clinical dysfunction index analysis. We measured the maximum bite pressure (MBP) and occlusal contact area (OCA) by means of a Fuji Prescale Pressure measurement film. Based on the MBP and OCA values obtained, MBF values were determined. Results: The MBF values were significantly lower in patients with TMD compared to subjects without TMD (P Conclusion: TMDs have a significant impact on MBF and masticatory muscle action potential. More research is needed to determine the impact of reduced maximum bite force on the functional efficiency of the masticatory system.

Unlike other oral care products, there are limited technologies in the denture adhesive category with the majority based on polymethyl vinyl ether/maleic anhydride (PVM/MA) polymer. Carbomer‐based denture adhesives are less well studied, and there are few clinical studies directly comparing performance of denture adhesives based on different technologies. This single‐centre, randomised, three‐treatment, three‐period, examiner‐blind, crossover study compared a carbomer‐based denture adhesive (Test adhesive) with a PVM/MA‐based adhesive (Reference adhesive) and no adhesive using incisal bite force measurements (area over baseline over 12 hr; AOB0–12) in participants with a well‐made and at least moderately well‐fitting complete maxillary denture. Eligible participants were randomised to a treatment sequence and bit on a force transducer with increasing force until their maxillary denture dislodged. This procedure was performed prior to treatment application (baseline) and at 0.5, 1, 3, 6, 9, and 12 hr following application. Forty‐four participants were included in the modified intent‐to‐treat population. AOB0–12 favoured both Test adhesive to No adhesive (difference: 2.12 lbs; 95% CI [1.25, 3.00]; p

In humans, the incisors and molars have distinct functions during mastication, analogous to the two main types of handgrip, the precision and power grips. In the present study, we investigated cortical activation and masticatory muscle activity during incisal and molar biting via simultaneous functional magnetic resonance imaging and electromyogram (EMG) recordings. We conducted recordings in 15 healthy adult participants while they performed incisal and molar biting tasks at three step-wise force levels using two custom-made splints. Regarding the results of the ROI analysis, we found a significantly stronger positive linear correlation between the blood oxygenation level dependent signal and EMG activity during molar biting than incisal biting, which was particularly prominent in the primary sensorimotor cortex and the cerebellum. We also found a significantly stronger negative linear correlation during incisal biting than molar biting, which was particularly prominent in the rostral cingulate motor area, superior frontal gyrus, and caudate nucleus. These findings indicate that molar biting enables powerful chewing: brain activity in several brain areas related to motor function was increased with increasing bite force levels, while incisal biting enables fine motor control: brain activity in several brain areas related to motor control was increased with reduced bite force levels.

The aim of this study was to investigate the fracture behaviour of fissural dental enamel under simulated occlusal load in relation to various interacting factors including fissure morphology, cuspal angle and the underlying material properties of enamel. Extended finite element method (XFEM) was adopted here to analyse the fracture load and crack length in tooth models with different cusp angles (ranging from 50° to 70° in 2.5° intervals), fissural morphologies (namely U shape, V shape, IK shape, I shape and Inverted-Y shape) and enamel material properties (constant versus graded). The analysis results showed that fissures with larger curved morphology, such as U shape and IK shape, exhibit higher resistance to fracture under simulated occlusal load irrespective of cusp angle and enamel properties. Increased cusp angle (i.e. lower cusp steepness), also significantly enhanced the fracture resistance of fissural enamel, particularly for the IK and Inverted-Y shape fissures. Overall, the outcomes of this study explain how the interplay of compositional and structural features of enamel in the fissural area contribute to the resistance of the human tooth against masticatory forces. These findings may provide significant indicators for clinicians and technicians in designing/fabricating extra-coronal dental restorations and correcting the cuspal inclinations and contacts during clinical occlusal adjustment.

OBJECTIVE: This study aimed to characterize amplitude topographies for masseter motor units (MUs) three-dimensionally, and to assess whether high-density surface electromyography (HDsEMG) is able to detect MU samples that represent the masseter's entire MU pool.METHODS: Ten healthy adult volunteers participated in the study, which combined three EMG techniques. A HDsEMG grid covering the entire masseter, and intramuscular fine-wire electrodes were used to obtain two independent MU samples for comparison. The MUs' amplitude profiles in the dimension of muscle depth were determined using scanning EMG. All data were recorded simultaneously during a low, constant contraction level controlled by 3D force feedback.RESULTS: The median medio-lateral diameter of 4.4 mm (range: 1.2-7.9 mm) for MUs detected by HDsEMG did not differ significantly (Mann-Whitney-U test, p = 0.805) from that of 3.9 mm (0.6-8.6 mm) for MUs detected by fine-wire EMG. For individual subjects, the medio-lateral diameters of all HDsEMG-detected MUs spanned 70.5% (19.2-75.1%) of the masseter's thickness.CONCLUSIONS: HDsEMG is able to examine small and large MUs from a great masseter proportion in one single measurement.SIGNIFICANCE: Clinical application of HDsEMG might contribute to a better understanding of neuromuscular adaptations in patients with temporomandibular disorders (TMD) and could allow for monitoring treatment effects.

Background/purpose: Acupuncture is well known to be effective for pain relief and muscle relaxation, and hence it is feasible that acupuncture treatment could change the occlusal forces and mandibular movements in subjects with deep-bite malocclusion. The purpose of this research was to determine the distribution of occlusal force and the border movement of the mandible in patients with deep-bite malocclusion before and after acupuncture treatment. Materials and methods: This study involved 17 volunteers with deep-bite malocclusion and aged 20–30 years. Before and after acupuncture treatment, the distribution of the occlusal-force percentage at each tooth was measured and the percentage biting force in the first molar area during maximal clenching was recorded. Additionally, the mandibular movements including the maximum mouth opening and maximum lateral border movement were also evaluated. All of the data were analyzed statistically using the Wilcoxon signed-rank test. Results: The percentage biting force at the first molar differed significantly between before and after the acupuncture treatments (P = 0.017). However, no treatment effects were seen for the maximum mouth opening and the maximum lateral border movement. Conclusion: Although the mandibular border movements did not change significantly, this study has confirmed that acupuncture treatment may become an alternative choice on improving the occlusal force of deep-bite patients. Keywords: Deep-bite malocclusion, Acupuncture treatment, Occlusal-force percentage, Mandibular border movement

Aim: The aim of this study was to compare the bite force and sedation score in moderate/conscious sedation for minor oral surgical procedure. Materials and Methods: A sample size of 30 was selected in each group (group M [midazolam] and group D [dexmedetomidine]). Results: Dexmedetomidine group had a statistically significant sedation score than midazolam. A statistically significant increase in the bite force was observed in both midazolam and dexmedetomidine groups, but there was no significant difference between the two groups. Conclusion: Dexmedetomidine and midazolam significantly increased the bite force because of the loss of proprioceptive function of periodontal ligament, but there was no significant difference between the drugs regarding bite force.

In dental research, bite force has become an important curative effect evaluation index for tooth restoration, periodontal treatment, and orthodontic treatment. Bite force is an important parameter to evaluate the efficacy of the masticatory system. Physicians obtain the therapeutic basis for occlusal adjustment by measuring the bite force and the dynamic changes in occlusal contact at different stages of treatment and objectively evaluate the therapeutic effect. At present, many devices are used to record the bite force. Most of these devices use force transducers to detect bite force, such as strain gauge transducers, piezoresistive transducers, piezoelectric transducers, optical fiber transducers, and pressure-sensitive films. This article summarizes the various equipment used to record bite force, related materials and the characteristics of this equipment. It provides a reference for physicians to make choices during the clinical process and at the same time provides a basis for the development of new occlusal force measurement materials.

Background In children with juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) can be involved, resulting in dysfunction of the masticatory system. Bite force is one of the variables that reflects the function of the masticatory system. The aim of this study was to compare maximum bite force in children with JIA, with and without TMJ involvement and with healthy children. Methods Children with JIA and healthy children between the ages 6 and 18 were included in this cross‐sectional study. The clinical examination consisted of measuring the anterior maximum voluntary bite force (AMVBF), assessment of the TMJ screening protocol items and TMJ, masseter and temporal muscle palpation pain. Unadjusted linear regression analyses were performed to evaluate the explanatory factors for AMVBF. Two adjusted models were constructed with corrections for age and gender differences: model 1 to compare children with JIA and healthy children and model 2 to compare children with JIA with and without TMJ involvement. Results In this cross‐sectional study, 298 children with JIA and 169 healthy children participated. AMVBF was 24 Newton (N) lower in children with JIA, when compared with healthy children (95%CI: −35.5–−12.4, p = .000). When children with JIA also had clinically established TMJ involvement, AMVBF was reduced 42 N (component JIA:−16.78, 95% CI −28.96–−4.59, p = .007 and component TMJ involvement:−25.36, 95% CI −40.08–−10.63, p = .001). Age and male gender increased AMVBF. Conclusion Children with JIA had a reduction in the AMVBF compared with healthy children. In children with JIA and clinically established TMJ involvement, AMVBF was more reduced., This study found a considerable bite force reduction and less functioning of the TMJ in children with JIA compared to healthy children, and even more reduction of these issues in children with JIA and TMJ involvement compared to JIA without TMJ involvement. For all children, the demographic variables age, length and male gender increased the maximum bite force.

The jaw system in canids is essential for defence and prey acquisition. However, how it varies in wild species in comparison with domestic species remains poorly understood, yet is of interest in terms of understanding the impact of artificial selection. Here, we explored the variability and interrelationships between the upper and lower jaws, muscle architecture and bite force in the red fox (Vulpes vulpes). We performed dissections and used 3D geometric morphometric approaches to quantify jaw shape in 68 foxes. We used a static lever model and bite force estimates were compared with in vivo measurements of 10 silver foxes. Our results show strong relationships exist between cranial and mandible shape, and between cranial or mandible shape on the one hand and muscles or estimated bite force on the other hand, confirming the strong integration of the bony and muscular components of the jaw system. These strong relationships are strongly driven by size. The functional links between shape and estimated bite force are stronger for the mandible, which probably reflects its greater specialisation towards biting. We then compared our results with data previously obtained for dogs (Canis lupus familiaris) to investigate the effect of domestication. Foxes and dogs differ in skull shape and muscle physiological cross-sectional area (PCSA). They show a similar amount of morphological variation in muscle PCSA, but foxes show lower variation in cranial and mandible shape. Interestingly, the patterns of covariation are not stronger in foxes than in dogs, suggesting that domestication did not lead to a disruption of the functional links of the jaw system.

The major causes of oral candidiasis include decreased salivary flow rate and the use of ill-fitting dentures. However, the relationships among prosthetic treatment, saliva, and Candida albicans have not been elucidated. This study aimed to examine the effects of prosthetic treatment and changes in saliva (mainly the salivary flow rate) on oral candidiasis symptoms. Participants requiring prosthetic treatment underwent testing for C. albicans, salivary flow rate, intraoral symptoms, and bite force at the initial visit and four months after treatment to evaluate pretreatment and post-treatment changes. The relationships among C. albicans, salivary flow rate, dentures, and intraoral symptoms were analyzed using multiple regression analysis. Denture treatment improved activity against C. albicans as well as the salivary flow rate, intraoral symptoms, and masticatory function. Multiple regression analysis revealed that changes in the stimulated salivary flow rate due to prosthetic treatment significantly improved C. albicans detection (p = 0.011), intraoral symptoms (p = 0.037), and bite force (p = 0.031). This study showed that prosthetic treatment improved salivary flow and intraoral symptoms and confirmed the influence of stimulated salivary flow rate changes.

Objectives. Bitewing radiographs are mainly used to confirm clinical findings in caries diagnostics. The objective here was to investigate the quality of bitewing radiographs after short brush-up training and additional findings besides caries in a low-caries population. Methods. The material of this cross-sectional study comprised 377 pairs of bitewing radiographs of 19- to 20-year-olds taken by dentists. Radiography was considered indicated if one dentinal caries lesion was present on clinical examination. A senior oral radiologist evaluated quality and diagnosed the findings afterwards unaware of clinical status. The association between variables was analysed using cross tabulation and chi-squared testing. Results. Almost half of the images were of compromised quality (44.1%). Dentinal caries lesions were detected in 82.3% and enamel lesions in 73.5% of the subjects. On average, the subjects had 1.7 (SD 0.52) dentinal lesions. Fillings were found in 81.8%, fractures/cracks in 11.7%, and attrition in 7.4% of the subjects. Signs of excessive bite force were recorded in 19.4%, whereas marginal bone loss was detected in 6.4%. No significant correlation was detected between fractures, attrition, and excessive bite forces. Conclusions. Effort must be taken to ensure high quality of bitewing radiographs. In addition to caries detection, bitewing radiographs offer additional value, such as detecting excessive bite forces, tooth wear, and marginal bone loss among young adults.

This longitudinal study aimed to clarify the relationship of oral health in infancy with that in adulthood among participants who were the subjects of the oral health promotion project (OHPP) conducted in Miyako Island, Okinawa Prefecture, Japan, since 1984. Twenty-seven subjects, around 35 years of age, were examined for dental caries, periodontal diseases (community periodontal index), dental plaque, occlusion, and bite-force and compared with those at 4 and 13–15 years of age. The dental caries status and maximum bite force in adulthood was significantly reflected for those at 4 and 13–15 years of age (p &lt, 0.05). CPI in adulthood was related to the dental caries status at 4 and 13–15 years of age but not to the gingival score at 4 years of age, and it was weakly related to the gingival score at 13–15 years (r = 0.264, p &gt, 0.05). Most of the normal occlusion at 4 years of age became normal permanent occlusion in adulthood (88.9%). Most of the cases involving the discrepancy factor retained the same condition in both the deciduous and permanent dentitions (83.3%) (p &lt, 0.001). Those who participated in the OHPP soon after birth showed significantly fewer DMFT (p &lt, 0.05) compared with those who did not. This study revealed that oral health at 4 years of age was related to that in adulthood, suggesting that fostering good oral health soon after birth is of great importance.

Dental implants are not routinely used for rehabilitation in veterinary dentistry. For some veterinarians, further studies are necessary to be considered for clinical use in animals. The objective of the present in vitro study was to evaluate static fatigue of dental implants and to correlate that with the bite strength of dogs described in the literature. Sixty implants and abutments were used with the smallest diameter of each brand of implant utilized in the study. Three groups ( n = 20) were created on the basis of the implant diameter, all with external hex connector: 3.30 mm (group 1), 4.0 mm (group 2) and 5.0 mm (group 3). All groups were subjected to quasi-static loading at 30° to the implant's long axis in a universal machine (model AME-5 kN). The mean fracture strength for group 1 was 964 ± 187 N, for group 2 was 1618 ± 149 N and for group 3 was 2595 ± 161 N. Significant differences between the groups with respect to resistance after the load applications were observed ( P

(1) Background: This study aimed to investigate maximum bite force (MBF) in elderly patients with natural full dentition (FD), patients rehabilitated with Traditional Complete Dentures (CD), with overdentures (IRO) and edentulous patients (ED). We also tested whether MBF changes are associated with gender, age of the patients and body mass index (BMI) as result of altered food, (2) Methods: Three hundred and sixty-eight geriatric patients were included. We studied two types of prostheses: (a) IRO with telescopic attachments. (b) CD (heat polymerized polymethyl methacrylate resin). The MBF was measured using a digital dynamometer with a bite fork., (3) Results: We found that MBF is higher in males than females, regardless of teeth presence or absence (p &lt, 0.01). In patients with CD or IRO, there are no differences between males and females, prostheses improve MBF compared to edentulous patients (p &lt, 0.0001) and this effect is greater with IRO prostheses (p &lt, 0.0001), the chewing force of FD subjects remains greater (p &lt, there are no differences among chewing strength based on different BMI categories, although FD subjects have a reduced incidence of obesity, there is a significant negative correlation between MBF and age (p = 0.038, R = 0.145), and no correlation between MBF and BMI., (4) Conclusions: This study showed that MBF improves more in patients using IRO prostheses, although not reaching the MBF of FD subjects. MBF does not correlate with BMI, although we found increased percentages of obesity in edentulous subjects or those with prostheses. Thus, old people wearing prostheses require special attention by a nutritionist to avoid risk of malnutrition.

The base fit between a removable partial denture (RPD) and the underlying soft tissue plays a significant role in its performance. The application of a denture adhesive is hypothesized to result in better retention of RPDs and, as a result, contribute to lower stress on the oral mucosa. The objectives of this study were to observe and compare the distribution of simulated bite forces applied to the RPD through the abutments and soft tissue for models with and without the use of a denture adhesive. Furthermore, we evaluated the possible benefit of using a denture adhesive in lowering stresses on the oral mucosa. The RPD, mandible, oral mucosa, abutment teeth supporting the RPD, and the corresponding abutment periodontal ligaments (PDLs) were modelled as 3D volumes based on computer tomography (CT) datasets. A viscoelastic adhesive layer between the RPD and oral mucosa was incorporated into this base model using Prony series approximation. The layer was developed as a volume extract using the denture surface. Finite element (FE) simulations were performed for the bite force on one of the RPD segments, with the resulting force and moments experienced by the dental structures and oral mucosa compared between the model with the adhesive layer and the base model without. As a result, the contact pressure on the oral mucosa for the model with the denture adhesive decreased to 0.15 MPa as compared to 0.25 MPa for the model without the adhesive. The potential role of denture adhesives in leading to a better fit between the RPD and oral mucosa as well as lowering contact pressures could be used to improve comfort in patients wearing RPDs.

Performance traits implicated in feeding interact directly with the environment and are consequently relevant ecological indicators. However, they have rarely been used to better understand palaeoenvironmental variation. Here, we evaluate the usefulness of a performance (i.e. functional) trait, estimated bite force, in reconstructing the palaeoecology of shrews. We investigate the relationships between mandible morphology, bite force estimates and the ecological context. We use geometric morphometrics to quantify mandible shape diversity in shrews of the archaeological site El Harhoura 2 (Rabat, Morocco), dated from the Late Pleistocene to the Holocene. Morphological groups were used instead of taxa as units of diversity. To explore how phenotypic traits are linked to their environment, they were compared with palaeoenvironmental inferences for the El Harhoura 2 site extracted from the literature. Morphological groups acted as phenotypic response units. Estimated bite force was related to palaeoenvironmental variation over the considered period, with a particular sensibility to arid/humid transitions. The complementarity of morphological and performance indicators allowed us to infer functional convergence and divergence among shrews. Our results suggest that functional traits may be relevant indicators of changes in palaeoenvironments. This approach opens up new possibilities to explore the impact of environmental changes on extinct organisms.

Made available in DSpace on 2021-06-25T10:20:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Objectives: The purpose of this study was to assess the effects of oral rehabilitation with complete dentures on bite force and electromyography of the suprahyoid and sternocleidomastoid muscles, and their correlation with occlusal vertical dimension (OVD). The research questions were “What are the effects of rehabilitation with complete dentures on bite force and electromyography of suprahyoid and sternocleidomastoid muscles, and how are they correlated with OVD?” Materials and methods: Patients who are wearers of unsatisfactory removable complete dentures were attended in three sessions (T0, T1, and T2). At T0, while the patients still wore the old dentures, they were submitted to bite force and surface electromyographic exams of the suprahyoid and sternocleidomastoid muscles. These exams were repeated, and the OVD was measured while the patients wore their old and new prostheses, 30 days after insertion of the new prosthesis (T1). The exams were repeated 100 days after the insertion of the new prosthesis (T2). The data were submitted to the Shapiro-Wilk normality test, analysis of variance (ANOVA), and Pearson correlation and linear regression, all with 5% significance. Results: Fifteen patients participated in the study. No statistically significant difference was observed for bite force or electromyography in T0, T1, or T2. However, the correlation and regression tests showed important interactions between the OVD and maximum voluntary occlusal bite force, as well as the OVD and electromyography during deglutition for the suprahyoid muscles. Conclusion: Rehabilitation did not impact bite force nor the activity of the assessed muscles (electromyography). On the other hand, OVD was shown to be an important factor for bite force, and deglutition of water after rehabilitation. Clinical relevance: This study shows what are the influences of rehabilitation on oral functions and reinforces the importance of corrected reestablishment of OVD because it has been found to be an important factor for bite force and electromyography during deglutition. Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) School of Dentistry Department of Support Production and Animal Health São Paulo State University (UNESP) School of Veterinary Medicine Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) School of Dentistry Department of Support Production and Animal Health São Paulo State University (UNESP) School of Veterinary Medicine

Objective To evaluate the impact of orthognathic surgery on the masticatory system of individuals with repaired cleft lip and palate (CLP) by means of bite force (BF) assessment. Material and methods Forty individuals were prospectively divided into 2 groups: 1) Control group (CON): 20 individuals without CLP (10 males, 10 females, 23.7y±7.4), 2) Cleft lip and palate group (CLP): 20 individuals with complete CLP with indication for orthognathic surgery (OS) (11 males, 9 females, 23.6y±5.6; 10 unilateral CLP; 10 bilateral CLP). The BF was evaluated in the immediate preoperative period (PRE), 3 months postoperatively (POST3M) and 6 months postoperatively (POST6M), using a gnathodynamometer (IDDK Kratos, Cotia-SP, Brazil). Results The BF of the CLP group was significantly lower than that of the CON in all evaluated periods. The BF of individuals with CLP was significantly lower in POST3M compared to PRE. Also, a significant increase in BF was observed between POST3M and POST6M. Though not significant, the BF was increased in POST6M when compared to PRE. The BF of unilateral and bilateral CLP individuals were statistically similar. Males presented a BF almost twice as high as females. Conclusion Cleft lip and palate negatively impacts BF. Although there was a tendency for BF values to increase 6 months after OS, it was still significantly reduced when compared to controls, not reaching normative values.

To compare two pain models of myalgic TMD, delayed-onset muscle soreness (DOMS) and injections of nerve growth factor (NGF), in terms of pain-related and motor function outcomes, as well as activity-related temporal summation. Methods: Fifty age- and gender-matched healthy participants were recruited and randomized into one of three groups: to a repeated eccentric contraction task to cause DOMS (n = 20), to receive NGF injections into the masseter muscle (n = 20), or to a control group (n = 10). Mechanical sensitivity of masticatory muscles, chewing parameters, jaw function limitation, maximum bite force, and activity-related temporal summation were assessed at baseline and at days 1, 2, and 7 following the intervention. Results: Compared to baseline, both model groups showed increased mechanical sensitivity, jaw function limitation, pain on chewing, and decreased chewing efficiency, lasting longer in the NGF group than in the DOMS group (P .05). Conclusion: Both models produced similar pain- related outcomes, with the NGF model having a longer effect. Furthermore, the NGF model showed a more substantial effect on motor function, which was not seen for the DOMS model. Finally, neither of the models were able to provoke activity-related temporal summation of pain. J Oral Facial Pain Headache 2020;34:311–322. doi: 10.11607/ofph.2623

Transcutaneous electrical nerve stimulation (TENS) is a non-invasive treatment modality for acute and chronic pain. However, little information for muscle activity is available on the immediate effects of TENS in masticatory muscle pain related to temporomandibular disorders (TMDs). The present study aimed to evaluate the immediate effects of TENS treatment on TMD-related muscle pain. Thirty-six patients with TMD-related muscle pain and 39 healthy subjects served as TMD and control groups, respectively. For objective evaluations, maximum mouth opening, and maximum bite force were measured before and after TENS. The pain intensity was assessed according to a 100-mm visual analog scale (VAS). TENS was applied to painful muscles for 20 min with frequencies of 100&ndash, 200 Hz. The treatment outcome was evaluated using Global Rating of Change (GRC) scales. In the TMD group, VAS values significantly decreased after TENS. Although there was significant increase in the maximum mouth opening after TENS for only TMD group, the maximum bite force of both groups was significantly greater after TENS. According to GRC scales, one patient with TMD-related muscle pain expressed negative feelings after TENS. Conclusively, TENS treatment might quickly relieve pain in masticatory muscles and improve masticatory functions in patients with TMD-related muscle pain.

Objective This study was performed to determine the maximum voluntary molar bite force (MVMBF) in relation to age, sex, lip competency, midline shifting, dental and skeletal malocclusion, overjet, overbite, and crowding. Methods One hundred Saudi patients with orthodontic malocclusion aged 14 to 25 years (51 male and 49 female patients) were investigated in this cross-sectional study. The baseline MVMBF on the right and left side was evaluated in all patients before commencing any orthodontic treatment. The MVMBF was registered with a portable occlusal force gauge in the first molar region during maximal clenching. Results The MVMBF significantly varied with respect to all nine confounding variables. The MVMBF significantly increased with an age of >18 years, male sex, right-side lip competency, no midline shift, dental and skeletal Class I malocclusion, normal overjet, normal overbite, and mild crowding. Conclusion All nine variables examined in the present study significantly influenced the MVMBF.