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PubMed1989

A new, simple and accurate method for evaluating masticatory ability.

A new method has been devised to measure masticatory ability. Pigment-coated granules were prepared, and 730 mg (730-740 granules) were sealed in a rubber capsule. This capsule was used as a test material and was chewed by the subject under standardized conditions. The masticatory ability, defined as the joules of work performed, was calculated based on the concentration of pigment leaked from the crushed granules during the process of mastication. The procedure is rapid, simple and reliable, and can be used for a large number of clinical samples and studies. The measurement error, defined as the coefficient of variation, was 2.1%. The intra-individual variation of measurements of twenty volunteers ranged from 3.6 to 16.9%. A series of tests in each subject was necessary to obtain a reliable value of masticatory ability.

Adult↗

PubMed1991

Mandibular movement and velocity in relation to state of dentition and age.

Parameters of mastication, such as mandibular displacement, velocity and chewing cycle duration, were investigated in relation to age and rehabilitation with complete dentures. Two groups of elderly subjects (mean age 80 years), one with natural dentition and the other with complete dentures, and one group of young dentate adults (mean age 26 years) participated. Three-dimensional records of masticatory mandibular movements were obtained using the Selspot movement analysis system. There were no differences in the duration of the total or individual components of a chewing cycle, except for the closing phase, which was significantly longer in the complete denture group. Mandibular closing velocity was significantly lower in the two groups of elderly subjects than in the group of young adults. There was a high degree of inter-individual variation in mandibular displacement in all groups, but the mean vertical amplitude was smaller in the elderly groups compared to the group of young adults. For many of the parameters the variation was significantly greater in the groups of elderly subjects than in the younger group. Ageing thus appeared to have a more important effect than the state of the dentition on the parameters studied.

Adult↗

PubMed1992

Longitudinal study on occlusal force distribution in lower distal-extension removable partial dentures with circumferential clasps.

In this study, longitudinal changes of the occlusal force distribution ratio were examined in lower distal extension removable partial dentures with cast circumferential clasps. Occlusal force applied to the denture base and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 4 months after. Two rates of loading were chosen. One was simulated mastication (fast loading rate) and the other was 10 Ns-1 (slow loading rate). Location of the loading points were first premolar (P1), second premolar (P2) and first molar (P3) of the denture. The occlusal force distribution ratio to the retainers was calculated when a load of 20N was applied to the loading point. The results are summarized as follows: (1) The occlusal force distribution ratio at fast loading rate on P1 and P2 was changed until 1 or 1 1/2 months after the insertion of the new dentures, and then became constant. This constant value was 30% on P1, 20% on P2 and 10% on P3. (2) Slow loading rate produced a greater ratio than the fast loading rate on P2 and P3 while there were no remarkable differences in the ratio between both loading rates on P1.

Aged↗

PubMed1992

The masticatory pattern as an adjunct for diagnosis and treatment.

The sagitally-viewed masticatory pattern was investigated in 125 dentate patients. In 25 patients, the phenomenon of an incisal guided phase during mastication was observed. Clinical examination of these cases revealed slight to severe incisal attrition or various degrees of flaring. The hypothesis that the incisal guided phase contributes to this phenomenon and should therefore be taken into consideration during treatment is put forward.

Adult↗

PubMed1993

Comminution of two artificial test foods by dentate and edentulous subjects.

An experimental artificial test food with low fracture strength (Optocal) was compared with Optosil with respect to the comminution during mastication by complete denture wearers and subjects with natural dentitions. The comminution of both test foods revealed large differences between the denture wearers and the dentate subjects. These differences were larger with Optosil than with Optocal. The differences in comminution between Optocal and Optosil were larger in the denture wearers than in the dentate subjects. The differences in comminution between the denture wearers and the dentate subjects as well as the differences in comminution between Optocal and Optosil within each group were largely established in less than 20 chewing strokes. The results indicate that differences in selection contributed substantially to the differences in comminution. Since Optocal appeared to be much easier to chew than Optosil, it may be preferred to Optosil for measuring masticatory performance in complete denture wearers.

Adult↗

PubMed1995

Electromyographic analysis of the masticatory muscles of patients after complete rehabilitation of occlusion with protection by non-working side contacts.

Surface electromyography was used to study the function of the anterior temporal, surface masseter, deep masseter and anterior digastric muscles of 14 patients after complete rehabilitation of occlusion with fixed prostheses and/or removable partial prostheses. All patients had a balanced occlusion with protection by non-working side contacts during lateral excursion. Mean resting myoelectric activity was 2.5-3.8 microV, showing no hypertonia or muscular spasm. When patients clenched their teeth (i.e. exerted maximum voluntary occlusal force in centric occlusion), the anterior temporal muscles were the most active, followed by the surface masseters; the digastrics were significantly less active. During lateral displacements, the muscles exhibiting significantly higher potentials than the other muscles monitored were the working side anterior temporal muscle and the contralateral surface masseter. During mastication, the muscle that was most active in relation to its contralateral homologue was the working side surface masseter, the difference between the two being statistically significant.

Adult↗

PubMed1995

Automated optical scanning for rapid sizing of chewed food particles in masticatory tests.

Analysis of the reduction in sizes of particles after chewing has been a standard method for assessing masticatory efficiency for over 40 years, but the sizing of particles with sieves is very time consuming. A rapid simple method of measuring chewed almond particle sizes by an optical scanning method has been developed and is described. The aim of this study is to validate the accuracy, repeatability and speed of the application of an optical scanning system in measuring chewed particles. To determine the accuracy, paper circles were measured and compared with the travelling microscope measurements. The effect of orientation of the images were assessed by measuring three irregular shaped pieces of paper and three different sized pieces of chewed almonds. Measurements were taken singly at 18 degrees increments from 0-180 degrees orientations with each piece of paper. To assess the repeatability of measuring chewed particles, the particles from a single masticated almond washed with water and absolute alcohol were spread, separated and measured by the optical scanning system. The samples were then remeasured 10 times. The reproducibility of the method was investigated using three repeated masticatory tests for each subject in a group of 13 young dentate subjects. The speed of spreading the particles and of measurement was assessed. The absolute error range for a mean area of 31 mm2 was 2.85% to 7.32% with a mean of 3.86%. The relative accuracy of measurement was higher for larger particles but in no case was the standard deviation > 0.4 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1995

Asymmetry of masticatory muscle activity during intercuspal maximal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome.

The present study investigated the asymmetry of masticatory muscle activity during maximal intercuspal clenching in healthy subjects and subjects with stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome, unilateral mastication and the asymmetry of masticatory muscle activity appear to be related to each other. The asymmetry of masseter muscle activity was greater as stomatognathic dysfunction became increasingly severe. Because fatigue and pain are produced more quickly by unilateral clenching than bilateral clenching, clenching under conditions of left and right muscular imbalance can further aggravate stomatognathic dysfunction. It is suggested the asymmetry of masseter muscle activity during maximal clenching correlates with the onset of the stomatognathic dysfunction syndrome. Stomatognathic dysfunction syndrome is closely related to the asymmetry of masseter muscle activity and only slightly related to the asymmetry of temporal muscle activity. The asymmetry of anterior temporal muscle activity appears to have little clinical significance.

Adolescent↗

PubMed1995

The effect of the slope inclination of buccal polished surface of mandibular denture base on food retention.

The accumulation of food debris in the buccal vestibule can inhibit normal mastication and appears to be a factor that can cause patient discomfort. This study focused on the effect of the slope inclination of the buccal polished surface of the mandibular denture base on the ability to expel test-food particles from the buccal vestibule. It was revealed that an inclination of the slope steeper than 80 degrees markedly inhibits the normal ability to expel foods from the vestibule. It was revealed that the most appropriate inclination of the buccal slope is approximately 60 degrees or 70 degrees. These results could be utilized for constructing a denture prosthesis.

Adult↗

PubMed1996

Patterns of jaw muscle activity during voluntary chewing.

Mastication is controlled by central rhythm and burst generators, but whether this control is similar under automatic and voluntary chewing is not clear. Our first aim was to determine whether increased chewing frequency led to a proportional decrease in both the burst duration (the time of muscle activity) and the interburst interval (time of inactivity) of each muscle or to a minimal decrease in the burst duration and a substantial decrease in the interburst interval. Our second aim was to determine whether these two manifestations of control differed between the opening and closing muscles. Electromyograms from digastric, medial pterygoid, masseter and anterior temporalis muscles were obtained during gum chewing by five subjects at four frequencies. A nearly fourfold decrease in total cycle duration (TCD) with increased chewing frequencies was accompanied by minimal changes in burst duration in the digastric muscle but proportional changes in the jaw closing muscles. The onset latency of the digastric muscle as a percentage of TCD decreased and became negative (i.e. occurred before opening started) as the TCD decreased. The onset latencies of the jaw closing muscles remained roughly 10-20% of the TCD for the three lower chewing frequencies. Control of the opening muscle appears to differ from control of the closing muscles.

Chewing Gum↗

PubMed1996

Long-term follow-up of cross-arch fixed partial dentures in patients with advanced periodontal destruction: evaluation of occlusion and subjective function.

The study aimed to investigate occlusal factors in fixed partial dentures (FPDs) still in service for more than 10 years, and to assess the patients' opinions regarding oral function with these constructions. Thirty-four patients with 43 FPDs were examined clinically concerning occlusion and by means of a questionnaire on functional aspects. The most common occlusal contact pattern was group function (51% on both sides, 7% on one side) while canine protected occlusion was recorded in 16% on both sides, 7% on one side. Balanced occlusion (19%) was mainly found when the FPD occluded against a complete denture and when there were few abutments and a small amount of abutment supporting tissue. The number and intensity of the occlusal contacts were assessed by means of thin occlusal sheets (50 microns). On average, one occlusal contact was observed on each dental unit with antagonist. The average number of sheets that could be introduced between the antagonists when the patient bit hard in the intercuspal position was two without significant differences between different areas (anterior/posterior) or type of dental unit (abutment, pontics, cantilever section). In the cantilever sections there were looser contacts (more interocclusal sheets) more distally. The great majority of patients were satisfied with the function of their FPDs (mastication, phonetics, aesthetics, comfort, and hygiene). Subjective function was not significantly influenced by FPD design, occlusal factors or number of FPD units. The only significant difference observed was that patients with a small amount of supporting tissues said they had more difficulties with hard foods than the others had. Although a stable occlusion was found in all FPDs, none of the other occlusal parameters examined were related to the long-term results.

Aged↗

PubMed2004

Effect of age on salivary flow obtained under feeding and non-feeding conditions.

Age, health status and disease treatments are thought to influence salivary flow. In this study, age effect on salivation was compared in non-feeding (at rest and during parafilm chewing) and feeding (during meat chewing) conditions for two groups of healthy subjects, 25 young subjects (mean age 27.4 years) and 20 old subjects (mean age 71.2 years). In non-feeding conditions, parotid flow was assessed at rest (3 min) and during parafilm chewing (1 min) from the absorptive capacity of a cotton roll placed in front of the upper duct apertures. Remaining saliva emanating mainly from the submandibular/sublingual glands was determined at rest by a sublingual cotton roll. In order not to impede in the chewing process during parafilm chewing, no cotton roll was placed in the lower part of the mouth and the remaining saliva was simply spit out for evaluation. Assessments were made under feeding conditions during the mastication of meat of different textures. The saliva content of the bolus was evaluated at different stages of the chewing process by weighing the mouth contents after spitting. No direct age effect was found on the different salivary flow rates measured during different conditions of stimulation. However, a significant correlation was found between the salivary flow rates at rest and those obtained during meat chewing in the elderly group but not in the young group. In elderly adults, rest salivary flow rate appears as a good predictor of salivary flow during the consumption of food. Within each group, significant correlations were found between salivation elicited by meat and by parafilm chewing. These results confirm the lack of direct global age effect on salivary flow rate by chewing in the 3 min after the stimulation, although adaptations to the measurement conditions are different between both groups of subjects.

Adult↗

PubMed2004

Chewing side preference as a type of hemispheric laterality.

Chewing side preference is a factor that could effect prosthodontic treatment. The purpose of this study was to determine whether chewing side was another type of hemispheric lateralization comparable with footedness, handedness, eyedness and earedness. Chewing side preference was tested in 189 subjects of whom 84 were partially edentulous, 98 had a full compliment of dental units (81 included implant-supported restoration restoring the missing teeth and 17 with fully intact dentitions), and seven were fully edentulous, restored with complete dentures. Laterality tests were carried out for the first cycle of mastication, handedness, footedness, earedness and eyedness and patient questionnaire. Most patients preferred chewing on the right side (78b3%) and were right sided. Chewing side preference correlated with other tested hemispherical lateralities. Missing teeth, occlusion type, lateral guidance, gender, implant-supported restorations and complete dentures do not affect the side preference for chewing. This presents a strong argument that chewing side preference is centrally controlled and provides food for thought regarding its significance in prosthodontics.

Adult↗

PubMed2006

Evaluation of transitional implant stabilized overdentures: a case series report.

Transitional implants (TI) can immediately improve the stability and retention of existing unstable mandibular complete dentures. This study evaluated the improvement of mandibular complete denture stability and retention with the use of TI. Three TIs were placed in the intraforaminal region of the edentulous mandible of seven patients (three men, four women; mean age 69.7 years). The patients' existing mandibular complete dentures were immediately modified to TI-stabilized overdentures. Their masticatory movements (mandibular movements during mastication) were measured using a commercially available tracking device (BioPACK, Bioresearch, Japan), both before TI placement and about 1 month after delivery of the TI-stabilized overdentures. The mean time of each chewing phase (opening, closing, and occluding) and coefficients of variation were calculated. The patients also completed a questionnaire about the foods they could chew and indicated on a 100 mm Visual Analog Scale (VAS) their personal levels of comfort, ease of chewing, speech, and stability. For masticatory movements, there were no significant differences (P > 0.05) between the TI-stabilized overdentures and existing complete dentures. However, the number of foods that could be chewed increased, and the stability and comfort were reported as improved with the TI-stabilized overdentures. Using TIs, the stability and comfort of the existing mandibular complete dentures studied in this report could be immediately improved.

Aged↗

PubMed2006

Individual difference in the number of chewing strokes and its determinant factors.

This study was carried out to clarify the distribution and individual variation of the number of chewing strokes before last swallowing (NCS), as well as to assess the factors that affect NCS, when dentulous adults masticate the same type of food. NCS was measured in 75 dentulous adults using gummy candies. Measurements were repeated five times to obtain the average and variation. Moreover, the correlation of NCS with various physiological factors (lateral width and vertical distance of chewing loop, angle of opening and closing path, opening and closing time, occlusal time, masticatory performance, number of occlusal contact points, occlusal contact area, occlusal force, flow rate of whole saliva and viscosity of whole saliva) and 28 personality factors were analysed by both of the single variate analysis and the multivariate analysis. The results showed that the average NCS was 41.0 +/- 16.0, and the coefficient of variation was 0.090 +/- 0.040. Additionally, the correlation between NCS and each factor was investigated, and found that any of these factors did not function as a single determinant for NCS. Following, determinant factors were further examined by the stepwise method of linear multiple regression analysis. From these analysis we found that when opening and closing time and four personality factors were combined, they were significantly involved in determining NCS (P < 0.01). Therefore, we conclude that individual NCS until last swallowing is not determined by a sole, specific physiological factor but is affected by multiple factors including personality.

Adult↗

PubMed2006

Measuring chewing ability in randomized controlled trials with edentulous populations wearing implant prostheses.

In this article, the authors review methods commonly used to measure the masticatory ability of patients wearing conventional and implant prostheses. Measurement approaches are viewed in two broad categories: laboratory based and patient based. The laboratory based measures discussed are mastication time, particle size, force measurements, patterns of jaw movement and electromyographic (EMG) bursts and total EMG activity. Patient based measures include satisfaction and chewing difficulty. Oral health-related quality of life measures and diet/nutrition variables are briefly mentioned. Patient-based outcomes are recommended as the most appropriate variables of masticatory efficiency.

Bite Force↗

PubMed2006

Sensory-motor function of human periodontal mechanoreceptors.

Natural teeth are equipped with periodontal mechanoreceptors that signal information about tooth loads. In the present review, the basic force-encoding properties of human periodontal receptors will be presented along with a discussion about their likely functional role in the control of human mastication. Microneurographic recordings from single nerve fibres reveal that human periodontal receptors adapt slowly to maintained tooth loads. Most receptors are broadly tuned to the direction of force application, and about half respond to forces applied to more than one tooth. Populations of periodontal receptors, nevertheless, reliably encode information about both the teeth stimulated, and the direction of forces applied to the individual teeth. Information about the magnitude of tooth loads is made available in the mean firing rate response of periodontal receptors. Most receptors exhibit a markedly curved relationship between discharge rate and force amplitude, featuring the highest sensitivity to changes in tooth load at very low force levels (below 1 N for anterior teeth and 4 N for posterior teeth). Thus, periodontal receptors efficiently encode tooth load when subjects contact and gently manipulate food using the teeth. It is demonstrated that signals from periodontal receptors are used in the fine motor control of the jaw and it is clear from studies of various patient groups (e.g. patients with dental implants) that important sensory-motor functions are lost or impaired when these receptors are removed during the extraction of teeth.

Adaptation, Physiological↗

PubMed1996

[The transverse movement of the temporo-mandibular joint (translation movement) of the dog, also with reference to dysplasia of this joint in the dachshund].

Contrary to the accepted opinion, transverse movement is possible in the temporo-mandibular joint of the dog. This movement is arched and is important for mastication. Analysis of transverse movement of the temporo-mandibular joint was done in 20 dog breeds. Accidentally dysplasia of the temporo-mandibular joint was found in the dachshund, a phenomenon which has not been described before.

Animals↗