Implant-supported prosthesis following Brånemark protocol on electromyography of masticatory muscles

Summary This research evaluated the effects of Brånemark protocol on electromyography of the masseter and temporal muscles. The patients were divided into two groups: Group I: patients who wore an implant‐supported prosthesis in the mandibular arch following Brånemark protocol, and maxillary removable complete dentures; Group II: dentate individuals (control). Electromyography was carried out at rest, right (RL) and left (LL) laterality, protrusion and maximum voluntary contraction (MVC). Data were compared by t‐test. At rest, a higher electromyographic (EMG) activity was observed in Group I, and the values were significant in the right masseter and left temporal muscles. In RL, there were statistically significant differences for right masseter (P < 0·01), left masseter and temporal muscles and for the left temporal muscle in LL (P < 0·05). In protrusion, Group I presented a higher EMG activity, and there was a statistically significant difference for the right masseter muscle (RM) (P < 0·05). In MVC, the EMG values were higher in Group II (control), but significant just for the right temporal muscle (P < 0·05). In conclusion, individuals with mandibular fixed dentures supported according to the Brånemark protocol and maxillary removable complete dentures showed a higher activity of masticatory muscles during the mandibular postural clinical conditions examined; however, in the MVC, Group I presented lower values when compared to dentate group. Despite presenting different EMG values in all of the clinical conditions, both groups showed similar EMG patterns of muscle activation which demonstrates that the proposed treatment can be considered as a good option for oral rehabilitation.     

Does malocclusion affect masticatory performance?

This purpose of this study was to evaluate the largely untested assumption that malocclusion negatively affects masticatory performance. A sample of 185 untreated subjects (48% male and 52% female) from 7 to 37 years of age, representing subjects with normal occlusion (n = 38), Class I (n = 56), Class II (n = 45), and Class III (n = 46) malocclusion, were evaluated. Masticatory performance was evaluated objectively using artificial (CutterSil, median particle size and broadness of the distribution) and real foods (number of chews for jerky and almonds), and subjectively using a visual analog scale. The results showed no significant differences in age or the body mass index (Wt/Ht2) between the occlusion groups. Subjects with normal occlusion had significantly smaller particle sizes (P = .001) and broader particle distributions (P < .001) than subjects with malocclusion. Compared with the normal occlusion group, the median particle sizes for the Class I, II, and III malocclusion groups were approximately 9%, 15%, and 34% larger, respectively. There were also significant group differences in their subjective ability to chew fresh carrots or celery (P = .019) and firm meat (P = .003). Class III subjects reported the greatest difficulty, followed by Class II subjects, Class I subjects, and subjects with normal occlusion, respectively. We conclude that malocclusion negatively affects subjects' ability to process and break down foods.     

Parkinson’s disease impairs masticatory function

Objective

To evaluate masticatory function in individuals with Parkinson’s disease (PD) during levodopa “on” period using new removable dental prosthesis.

Materials and methods

A total of 34 elderly individuals with PD (n = 17, mean age = 69.41 ± 4.65 years) or without PD (n = 17, mean age = 70.71 ± 4.65 years) were recruited for this study. Participants received new complete dentures and/or removable partial dentures. Two months after the subjects were free of any prostheses discomfort, masticatory function was assessed. A kinesiographic device was used to measure the range of jaw motion and jaw movements while chewing a silicone test material (Optocal). Masticatory performance was determined by median particle size (X₅₀) of the Optocal after 40 masticatory cycles. Maximum bite force was assessed by a strain sensor placed in the bilateral first molars region. Data were analyzed by t test (P < 0.05).

Results

The PD group showed a decreased range of jaw motion, longer duration and slower velocity of the masticatory cycle (P < 0.05), higher X₅₀ value, and lower maximum bite force (P < 0.05).

Conclusion

PD patients have impaired masticatory function during levodopa “on” periods compared to controls.

Clinical relevance

Knowledge that PD is associated with impaired masticatory function is important to dental professionals in decision making related to prosthetics and general dental treatment.

     

Comparison of masticatory efficacy among complete denture wearers with two adhesives and dentate individuals: A randomized,crossover, double-blind clinical trial

Statement of problem

The masticatory efficacy between dentate and edentulous individuals with and without the use of dental adhesives has been little studied. A comparative study of the addition of various agents of synthetic adhesion (vinyl methyl ether versus polyvinyl acetate) to these adhesives is needed.

An anatomical study of muscle-bone junction in human masticatory muscles —Macroscopic, immunohistochemical and scanning electron microscopic analyses—

In this study, seventy adult humans were selected at autopsy from donations at Nippon Dental University for macroscopic, histochemical, and scanning microscopic analyses of the muscle-bone junction in mandible. The following results were obtained.

Influence of palatal coverage on oral function: – Oral stereognostic ability and masticatory efficiency

PurposeOral sensorimotor function performs an important role in mastication. This study investigated the influence of wearing experimental palatal plates on masticatory efficiency and oral stereognostic ability (OSA), and the relationship between these two functions.MethodsFifteen young adults with healthy dentitions (mean age, 26.4 years) participated in this study. Masticatory efficiency was determined using a sieving method and OSA test was conducted by 12 shaped forms. These tests were performed in random order under three different conditions: control (without experimental plate), Plate-A (a horseshoe-shaped and 10 mm in width from the gingival cuff) and Plate-B (the entire palate was covered). The thickness of experimental plate was 1.5 mm. The statistical significance level was set at P < 0.05.ResultsMasticatory efficiency was significantly reduced with Plate-B, but not with Plate-A, compared with control. OSA scores were not significantly influenced by the presence of either plate. A significant positive correlation existed between masticatory efficiency and OSA score in control and with Plate-A, but not with Plate-B.ConclusionWe suggest that wearing Plate-A had no influence on masticatory efficiency and did not disturb oral sensorimotor control of the masticatory mechanism, while wearing Plate-B reduced masticatory efficiency and might have an effect on the relationship between OSA and mastication in young dentate adults.     

Psychological stress-relieving effects of chewing — Relationship between masticatory function-related factors and stress-relieving effects —

Purpose

The objective of the present study was to investigate the relationship between masticatory function-related factors (masticatory performance, occlusal contact area, maximum bite force, number of chewing strokes, and muscle activity) and the stress-relieving effects of chewing.

Rhythm and amplitude of rhythmic masticatory muscle activity during sleep in bruxers – comparison with gum chewing

Objectives: The aim of this study was to elucidate characteristics of rhythmic masticatory muscle activity (RMMA) during sleep by comparing masseteric EMG (electromyogram) activities of RMMA with gum chewing.

Method: The parts of five or more consecutive phasic bursts in RMMA of 23 bruxers were analyzed. Wilcoxon signed-rank test for matched pairs and Spearman’s correlation coefficient by the rank test were used for statistical analysis.

Results: Root mean square value of RMMA phasic burst was smaller than that during gum chewing, but correlates to that of gum chewing. The cycle of RMMA was longer than that of gum chewing due to the longer burst duration of RMMA, and variation in the cycles of RMMA was wider.

Discussion: These findings suggest that the longer but smaller EMG burst in comparison with gum chewing is one of the characteristics of RMMA. The relation between size of RMMA phasic bursts and gum chewing is also suggested.     

Patterns of cervical and masticatory impairment in subgroups of people with temporomandibular disorders–an explorative approach based on factor analysis

Objectives: To identify clinical patterns of impairment affecting the cervical spine and masticatory systems in different subcategories of temporomandibular disorder (TMD) by an explorative data-driven approach.

Methods: For this observational study, 144 subjects were subdivided according to Research Diagnostic Criteria for TMDs into: Healthy controls, temporomandibular joint (TMJ) signs without symptoms, TMJ affected, temporomandibular muscles affected, or TMJ and muscles affected. Factor analysis and linear regression were applied to cervical spine and masticatory data to identify and characterize clinical patterns in subgroups.

Results: Factor analysis identified five clinical dimensions, which explained 59% of all variance: Mechanosensitivity, cervical movement, cervical and masticatory dysfunction, jaw movement, and upper cervical movement. Regression analysis identified different clinical dimensions in each TMD subgroup.

Conclusion: Distinct clinical patterns of cervical spine and masticatory function were found among subgroups of TMD, which has clinical implications for therapeutic management.     

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

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

The eligibility of the free fibula graft for masticatory rehabilitation using monocortical implants insertion—a morphologic and biomechanical study

The use of the vascularized fibula graft has already been established for reconstruction of the mandible following ablative surgery. In order to reconstruct the vertical height of the alveolar process and improve implant position as well as angulation, some therapeutic options are available, including primary use of the fibula as a double-barrel graft and vertical distraction as well as later augmentation with avascular bone grafts. We analyzed the anatomic and morphologic features in 40 fibula bones of 20 cadavers and provided the mean cortical thickness of different transplant sites. Furthermore, we investigated the primary implant stability of dental implants inserted monocortically in harvested fibula segments using established biomechanical methods as well as Periotest?. The minimal bone height of the clinically relevant segments of the fibula transplant measured 9.06 ± 0.45 mm, which was assessed in the most distal part. In contrast, a maximal total bone height of 15.46 ± 0.78 was observed in the middle segment of the fibula bone. We assessed sufficient primary stability in all inserted implants as well as a reliable relative micro-movement of the implants in the fibula bone. Fibula graft as a single-barrel graft alone may provide through monocortical implant insertion a further refinement of the method to fit complex requirements and shorten prolonged therapeutic procedures. Monocortical implant insertion in the fibula graft would simplify oral rehabilitation after ablative surgery of the jaw and reduce costs as well as therapy period.     

Can oral health promotion help develop masticatory function and prevent dental caries?

OBJECTIVE: In an effort to promote adequate development of the masticatory system and prevent dental diseases, the Oral Health Promotion Project (OHPP), which focuses on diet, was started in 1984. The intervention was carried out over eight years and then followed up for a further nine years, in a district with no regular dental service, on Miyako Island, Okinawa, Japan. The aims of this study were to evaluate the project's effect on dental caries and masticatory function. RESEARCH DESIGN: Longitudinal data on the complete deciduous dentitions(IIA) at age 4 (n=163) and on the permanent dentition (IVA) at age 13-15 (n=112) were compared to control age-matched groups, aged 4 (n=105) and aged 13-15 (n=70). The control data were collected from a neighbouring district. Instructions on diet were gradually introduced to those in charge of the subjects' food regimes. RESULTS: Mothers reported that children born after the OHPP was begun took less snacks and caloric drinks (p<0.001) and more fibre-rich food (p<0.05) than those who born before the start of the project. The number of carious teeth decreased significantly among subjects born after the start of the project. The masticatory function was summarized in one factor using chewing performance, bite force, muscle activity duration time (using EMG) and mean amplitude of muscle activity. The factor score was higher for those born after 1984 than for those born in 1981-1983 and for those in the control district (GLM, p<0.001). CONCLUSION: It is suggested that OHPP can promote the masticatory function and prevent dental caries, but that it would be crucial to begin intervention soon after birth.     

Does a mandibular RDP and new maxillary CD improve masticatory efficiency and quality of life in patients with a mandibular Kennedy class I arch?

Objectives

To evaluate the change in masticatory efficiency and quality of life of patients treated with mandibular Kennedy class I removable partial dentures (RPDs) and maxillary complete dentures at the Department of Dentistry of the Federal University of Rio Grande do Norte.

Materials and methods

A total of 33 Kennedy class I patients were rehabilitated with maxillary complete dentures, and mandibular RPDs were selected for this non-randomized prospective intervention study. The patients had a mean age of 59.1 years. Masticatory efficiency was evaluated by colorimetric assay using fuchsin capsules. The measurements were conducted at baseline and 2 and 6 months after prosthesis insertion. Quality of life was evaluated using the Oral Health Impact Profile (OHIP-14) at baseline and 6 months after denture insertion. The Kolmogorov-Smirnov normality test was applied. Masticatory efficiency was evaluated by repeated measures ANOVA. Oral health-related quality of life was compared using the paired t test.

Results

There was no statistically significant difference in masticatory efficiency after denture insertion (p?=?0.101). Significant differences were found (p?=?0.010) for oral health-related quality of life. A significant improvement in psychological discomfort (p?<?0.01) and psychological disability (p?<?0.01) was observed. Mean difference value (95 % confidence interval) was 6.8 (3.8 to 9.7) points, reflecting a low impact of oral health on quality of life, considering the 0–56 range of variation of the OHIP-14 and a Cohen’s d of 1.13.

Conclusion

According to the results of the present study, rehabilitation with Kennedy class I RPDs and complete dentures did not influence masticatory efficiency but improved oral health-related quality of life.

Clinical relevance

The association between the patient’s quality of life and the masticatory efficiency is important for treatment predictability.

     

Natural mediotrusive contact: does it affect the masticatory and neck EMG activity during tooth grinding?

Objectives: There is scarce knowledge regarding the influence of a natural mediotrusive contact on mandibular and cervical muscular activity. The purpose of this study was to analyze the EMG activity of the anterior temporalis (AT) and sternocleidomastoid (SCM) muscles during awake grinding in healthy subjects with or without a natural mediotrusive occlusal contact.

Method: Fifteen subjects with natural mediotrusive occlusal contact (Group 1) and 15 subjects without natural mediotrusive occlusal contact (Group 2) participated. Bilateral surface EMG activity of AT and SCM muscles was recorded during unilateral eccentric or concentric tooth grinding tasks. EMG activity was normalized against the activity recorded during maximal voluntary clenching in intercuspal position (IP) for AT muscles and during maximal intentional isometric head-neck rotation to each side, for SCM muscles.

Results: EMG activity of AT and SCM muscles showed no statistical difference between groups. EMG activity of AT muscle was higher in the working side (WS) than in the non-WS (NWS) in Group 1 during concentric grinding (0.492 vs 0.331, p?=?0.047), whereas no difference was observed in Group 2. EMG activity of SCM was similar between working and NWSs in both groups and tasks. Asymmetry indexes (AIs) were not significantly different between groups.

Discussion: These findings in healthy subjects support the assumption that during awake tooth grinding, central nerve control predominates over peripheral inputs, and reinforce the idea of a functional link between the motor-neuron pools that control jaw and neck muscles.