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At least 1,117 records · Page 62Linked to original sources
PubMed1997

[The effects of soft denture liners applied to complete dentures on masticatory functions].

The soft denture liner was applied to dentures for the edentulous patients with poor residual ridge and thin mucosa. It is useful for minimizing the soreness caused by the denture during mastication, however, its effect on masticatory functions has been rarely investigated. The purpose of this study was to determine the effect of a soft liner applied to complete dentures on masticatory functions. Five edentulous volunteers who were satisfied with their new complete dentures took part in this study. The lower dentures were lined with a soft liner. Comparison of occlusal force, masticatory performance, masseter muscular activity, and mandibular movement were made between new dentures and relined dentures. The results of applying soft materials to lower dentures obtained by comparison with complete dentures using hard acrylic resin bases were follows: 1. Occlusal forces were significantly larger (p < 0.01). 2. Masticatory performance in chewing peanuts increased slightly. The number of strokes and time for masticating a peanut decreased significantly (p < 0.01). 3. Masticatory muscles functioned more rhythmically and mandibular movements became smoother. 4. Integrated EMGs per stroke of all patients was similar.

Aged↗
PubMed1997

Simulation of jaw-movements for the musculoskeletal diagnoses.

Simulations of static and dynamic aspects of the functionality of the human body are getting more important as the complexity of operations increases. The preoperative planning of maxillofacial operations like the repositioning of the jaw is an example for such operation. Here, but also in other medical fields, simulation can help to estimate the results of a procedure or can facilitate the diagnosis through a better view of the anatomy and pathology of the patient. A virtual view on the pathology and the possibility of simulating the postoperative results simplifies and improves the preoperative planning. The goal of our research is the development of a graphical simulation of the human mastication system to give the surgeon an impression on the inner anatomy of his patient. This simulation allows him to predict the aesthetic and functional outcome of his operation. The main focus of this paper is the introduction of a kinematic model of the temporomandibular joint. This kinematic model describes the geometrical and analytical movement of the jaw by specially defined axes. It is the basis for an animated simulation of the mandible movement. Through integration of the muscles and muscle forces, we come to a realistic dynamic simulation of the whole mastication system.

Computer Simulation↗
PubMed1976

[Problems of prosthetic treatment following preprosthetic measures in the maxilla].

The experiences with prosthetic treatment of the maxilla, following praeprosthetic surgery have been examined. It is of significance that this surgical intervention does not always result in a more favorable jawform and interalveolar relationship, factors which help determine the stability of the denture during mastication. The postoperative prosthodontic treatment of maxillary resorption remains problematical quite often becoming still more complicated because of additional problems in part undiagnosed by the dentist. Some of these problems and their solutions are discussed in a clinical case. The importance of denture stability during mastication independent of other retentive factors is emphasized as well as an occlusion coordinated with the "condyle in fossacentric" and the chewing strokes. The disregard of these stabilizing and retentive factors is too frequently the cause of praeoperative as well as postoperative failure in addition to contributing to accelerated residual ridge resorption.

Bone Resorption↗
PubMed1998

The measurement of physiological tooth displacement in function.

The purpose of this work was to investigate the physiological tooth displacement in function. We developed the tooth displacement transducer Type M-3 and measured the three dimensional displacement of the upper and lower left first molars in function. The summary is as follows: 1. Magnesensors were used in the tooth displacement transducer Type M-3. Its total weight was 48.7 g. and the measuring pressure was kept less than 0.4 g. It was fixed at the labial surface of the anterior teeth using a paraocclusal splint. 2. The linearity error of the transducer was less than 2% within a range of +/-200 microm. 3. The upper left first molar showed displacement in the palatal and apical direction during clenching at the intercuspal position with habitual occlusal force or during the biting of articulating papers. The displacement varied between 40 and 136 microm. 4. The lower left first molar showed displacement in the apical and lingual direction during clenching at the intercuspal position or during the biting of articulating papers. The displacement varied between 29 and 65 microm. 5. The upper left first molar showed displacement in the palatal and apical direction during mastication. The displacement varied between 68 microm and 79 microm. The upper teeth moved first in the apical direction, then moved toward the labial direction. 6. In the lingual direction, the lower left first molar showed displacement ranging from 11 to 71 microm and 17 to 39 microm in the buccal direction during mastication.

Adult↗
PubMed2001

[The effect of the hyper-erupted third molar on chewing movement].

OBJECTIVE: To investigate the effect of the hyper-erupted third molar contacting closely to the distal surface of the opposing second molar on the chewing movement. METHODS: Twenty-three university student volunteers, 11 with hyper-erupted third molar teeth and 12 with normal occlusion, were enrolled in present study. There were totally 6 unilateral hyper-erupted third molars (3 upper and 3 lower) and 5 bilateral hyper-erupted third molars (1 bilateral upper and 4 bilateral lower). No other significantly abnormal occlusal phenomenon was observed. Five gum-chewing cycles masticated with an each side were separately recorded by means of K6-I mandibular kinesiograph (MKG) and the chewing cycles were analyzed. Both three-dimensional amplitudes and the related velocities were automatically documented with the instrument. RESULTS: (1) The chewing graphs recorded on both frontal and horizontal planes in controls were typically smooth cycles with clearly occlusal phase tracings. On the sagital plane the opening and closing traces around intercuspal position (ICP) were usually overlapped with each other. (2) 63.6% frontal cycles of the subjects with hyper-erupted third molar had an obvious table (0.2 mm to 1.0 mm in width) around ICP, 50% horizontal cycles of the subjects had a 0.2 mm to 0.5 mm step near to ICP, 72.7% opening and closing traces on the sagital plane separated into anterior and posterior branches. The abnormal traces on the three different planes of the hyper-erupted third molar tooth group appeared to be related each other, implying that they might be caused by the same characteristics of occlusion, namely, the hyper-erupted third molar. (3) Subjects with hyper-erupted third molar masticated in more posterior direction, together with a higher chewing terminal velocity. CONCLUSIONS: The hyper-erupted third molar had a significant effect on the chewing cycles around ICP, as well as on the amplitude and velocity of chewing movement.

Adolescent↗
PubMed2002

Electromyographic study of the masseter muscle in individuals with Class II malocclusion.

The objective of this work was to study the action of the masseter muscle through electromyography and to analyze the difference of action potential generated by several pre-established jaw movements in individuals with Class II malocclusion. It was studied nine young individuals from both sexes, with ages ranging from 17 to 35, with no history of orthodontic treatment and/or having some kind of alteration in the temporomandibular joint (T.M.J.). In order to collect the electromyographic signs we have used a TECA TE-4 Electromygraph and surface electrodes type Beckman. The data were submitted to nonparametric statistical analysis by Friedman test. The response variables left occlusive contact, free protraction, protraction with occlusive contact, incisor mastication, right molar mastication and forced central occlusion movements showed significant outcomes. Thus we have concluded that as the occlusive balance suffers alterations, the malocclusions become predominant and the masseter muscle undergoes functional and structural modifications.

Action Potentials↗
PubMed2002

Effects of a denture adhesive on masticatory functions for complete denture wearers--consideration for the condition of denture-bearing tissues--.

The purpose of this study was to examine effects of a denture adhesive on masticatory functions for complete denture wearers considering the condition of denture-bearing tissues. Sixteen edentulous subjects wearing well-fitting complete dentures volunteered to participate in this study. According to the condition of denture-bearing tissues, subjects were divided into two groups; "good group" and "poor group". Maximum biting forces, masticatory performance, and electromyography of the masseter muscle during mastication were recorded with and without a denture adhesive. Durations of chewing burst and cycle, and coefficients of variation for these variables were calculated using electromyography recordings. Data were analyzed by using two-way repeated-measured ANOVA and paired t-test in order to assess the effect of the use of a denture adhesive. The use of the denture adhesive increased maximum biting force and provided rhythmic masseter muscle activity during mastication for both groups. Masticatory performance was improved and duration of chewing burst was decreased only for "poor group". It was concluded that the effects of the denture adhesive on masticatory functions were observed overall for both groups, and more significant for denture wearers with poor denture-bearing tissues than with good denture-bearing tissues.

Adhesives↗
PubMed2004

Influence of length of food platform on masticatory performance in patients missing unilateral mandibular molars with distal extension removable partial dentures.

Reduction of the size of food platform of a distal extension removable partial denture has been recommended to decrease functional load on the abutment teeth and residual ridges. The purpose of this study was to investigate the influence of shortening food platform on masticatory performance. Eight subjects unilaterally missing mandibular molars participated in the study. A unilateral design was used for the denture framework. The length of the food platform was changed as follows. Initially, (A) was adjusted so that the distal end of the platform was in accordance with the distal end of maxillary second molar. Next, the platform was shortened successively to 15 mm (B) and 10 mm (C). Subjects were asked to masticate 2-colored wax cubes to evaluate masticatory performance. Mixing Ability Index was calculated from the color mixture and the form of masticated cubes. Repeated measures one-way ANOVA indicated significant difference of Mixing Ability Index among platforms (P < 0.0001). The Dunnett's test indicated no significant difference between A (1.27 +/- 0.29) and B (1.36 +/- 0.29), and a significant difference between A and C (0.89 +/- 0.30), (P < 0.001). Masticatory performance decreased significantly when the length of food platform was shortened to 10 mm.

Acrylic Resins↗
PubMed2004

[Determination and analysis of masticatory performance of nonfree-end removable partial denture].

OBJECTIVE: The purpose of this study was to evaluate the changes of masticatory performance of the cases wearing dentures and relative factors. METHODS: The changes of masticatory performance of the cases wearing dentures were studied before and after wearing by using the light absorption method and peanuts as test food. RESULTS: The mastication performance of the experimental groups was predominantly lower than that of the control groups. The masticatory performance was gradually improved with wearing denture period increasing. Factors relating to the masticatory performance were age, number of occlusal units lost and the kind of denture, and the number of chewing etc. CONCLUSION: The mastication performance of the experimental groups was dominantly lower than that of the control groups, but gradually improved with wearing denture period increasing. Varied factors affect the masticatory performance of experimental groups.

Adult↗
PubMedDate not supplied

Relationship between duration of unilateral masticatory cycles and the type of lateral dental guidance: a preliminary study.

PURPOSE: This study assessed the duration of different phases of the chewing cycle and the height of the masticatory cycle in relation to the type of lateral guidance. MATERIALS AND METHODS: Fifty-three subjects with the same type of lateral guidance on both sides were categorized into 3 groups: anterior protected articulation, canine protection, and group function. Overbite was measured clinically. Border jaw movements were recorded using a Sirognathograph, and the lateral guidance angle in the frontal plane was measured. Jaw movements during unilateral chewing of peanuts were recorded on the frontal plane using the Sirognathograph connected to an electrocardiograph used for transcription. A single masticatory cycle was divided into opening, closing, and occlusal-level phases. Masticatory parameters were analyzed by one-way analysis of variance, correlations, the paired Student t test, and multiple linear regression. RESULTS: Women showed significantly longer total cycle duration than men. Subjects with canine protection showed the highest lateral guidance angle and the highest chewing cycle duration. Subjects with anterior protected articulation exhibited significantly longer occlusal-level phases. Fifty-nine percent of the variation in duration of the occlusal-level phase can be explained by the type of lateral dental guidance, gender, and lateral guidance angle. Only overbite was a predictor of height of mastication. CONCLUSION: The type of lateral guidance, gender, and frontal guidance angle are correlated with the duration of the occlusal-level phase during unilateral chewing of peanuts. The height of mastication cannot be explained by the type of lateral guidance.

Adult↗
PubMed1991

Effect of the infraorbital nerve transection on the sensory input subsystem in the masticatory system of newborn mice.

To confirm a hypothetical idea that the masticatory system will play a fundamental function in the postnatal growth of the body, the centripetal mastication-related information flowing in the system was interrupted by cutting the infraorbital nerve on the newborn mice. The sham- and axotomy-operation mice were returned to their mother. 20 days after the operation the sensory input unit was studied in the serial frontal section histologically. On the other hand the body weight was measured every 5 days after the operation and the significant level was examined statistically. The results obtained are as follows: 1) The sensory input units (primary and secondary sensory neurons) have completely reduced to disappear in situ. 2) The significant differences between both groups were seen at the level of P less than 0.001 from the period of 20-day after the operation. In comparison with that of the sham-operation mice, the axotomy-operation mice have decreased about 20 to 30% in the body weight and so reduced in shape, characterized by the smaller head, a shorter trunk and limbs and a shorter, thinner tail. The experimental data suggest that the centripetal mastication-related information plays an important role in the postnatal growth of the masticatory system and the other functional systems of the body.

Animals↗
PubMed1991

[Median inter-incisor line. Clinical symptomatology].

Since unilateral mastication causes asymmetry of mouth and face, a child's interincisal midline can reveal the first signs of alteration of masticatory function. Early detection of the functional pathology, preferably before it has established itself as such, allows the clinician to correct it by means that are relatively unburdensome for the patient, thereby forestalling severe organic alteration and favouring proper, balanced occlusal development. Centering the mandible in stable centric occlusion, together with simple treatment promoting alternating bilateral mastication, allows the correct development of the growing patient's stomatognathic system.

Centric Relation↗
PubMed1990

[Homage to Pedro Planas].

It has been known since the time of Claude Bernard that the "function makes the organ" and ensures its development. However, it took Planas to discover that the masticatory function is the principal factor related to the development of the jaw! Nonetheless, this function only attains its objective if it is physiologically normal, grinding of food taking place by alternative laterality, which can only occur according to Gysi with a balanced occlusion, in conformity with Hanau's rules: opening-closing type mastication as a result of another type of occlusion leads to maxillo-alveolar sub-development and lack of sufficient space. Neuro-Occlusal Rehabilitation (N.O.R.) attempts to detect the type of mastication and occlusion at an early age, to correct it as from the age of 3 years by selective grinding in order to establish alternative laterality: true prophylaxis. If the grinding function is not adequate because it has been corrected too late, Planas appliances are used. Post-orthodontic stability is remarkable as the treatment uses natural and normal means of development.

Adolescent↗
PubMed1990

[In vivo radiotelemetric study of strain on the rabbit mandible].

Using strain transducer to measure bone strain and stress in vitro on-line techniques are more popular. In this article, the radiotelemetric method is selected for measuring living tissue mechanic properties. The angle of rabbit mandible serves as tested site. The transducer is minutely foil type electrical resistance strain gage. The measuring instruments are KYOWA telemeter for strain measurement MRT-200 series. When the mandible is in rest position, the tested site shows no change of strain; when the mandible acts without eating any food, small change of strain appear; when the rabbit mastication two kinds of food, the tested site shows the regular change of tension strain and compressive strain, the former is about 150 microstrain and latter is about 30 microstrain. The rates of strain are different when the animal mastication the different foods. Comparing with the on-line technique method, the radiotelemetric method has significant advantages, and is the better test way for studying mechanic properties of living tissue.

Animals↗
PubMed1990

[Cases of prosthodontic tissue reconditioning in geriatric dentistry].

In elderly patients, recurrent fractures of the lower denture must raise the question of a neurological deficit as cause of the occluso-prosthetic imbalance. Hypotonicity of the peri-oral mastication musculature, especially the masseters, may explain the alteration of the prosthetic supporting surface due to shriveling of the mandibular arch, along with an osseogenesis at the point of flexion of the mandible. The rest and activity muscular imbalance, resulting from unilateral mastication, may cause lingual dysfunction and deviation of the tongue at rest. If this problem is not controlled within an acceptable period of time, one should expect psychological, biological and physiological consequences affecting the patient's physical condition. The restoration of the denture fracture is insufficient. Reconditioning must be performed in order to replace the existing prosthesis in the patient's function, allowing him/her to recover a normal psychological, biological and physiological balance. In conclusion, in geriatric dentistry, the objective of reconditioning is, not only to restore a functional occlusion, but also the psychological, biological and physiological balance of the patient. This is an unvaluable advantage, especially if this contributes to maintain or restore an often precarious health.

Aged↗
PubMed1990

[Quantitative analysis of the rythm of feeding and merycismal activities].

The nycterohemeral eating and ruminating patients were studied in 6 heifers given ad libitum access to grass or corn silage in a 2 period cross-over design. Rhythm components (no of cycles/24 h) were characterized by the finite Fourier transform of hourly means of the 24 h mastication activities. Rhythm components 1, 3 and 4 contributed considerably to explaining the total dispersion of 24 h eating and ruminating mastication series.

Animals↗
PubMedDate not supplied

[A new method of evaluation of the masticatory function in humans].

A method is proposed to estimate mastication by three indices: chewing effect, chewing performance, chewing efficiency. Definitions are given for these terms. A new chewing test is described, permits studying the influence of the number of chewing strokes, chewing force and volume of test portion on the mastication using a group of 25 dentate persons aged 17-25 years with class I occlusion. A new approach to the estimation of chewing efficiency changes traditional views. A strong positive correlation is first found between chewing effect (A) and integrated bioelectrical activity (J) of chewing muscles with the constant number of chewing strokes. A relation between A and J is established when the number of chewing strokes increases.

Action Potentials↗
PubMed1989

Prosthetic rehabilitation of mandibulectomy and glossectomy patients.

The prosthodontic prognosis in patients with lateral discontinuity defects of the mandible is dependent on a number of complex factors. In some patients only esthetics can be improved, whereas in others mastication and speech improvement can be achieved. Two patients who had undergone the same surgical interventions but presented with different problems are described. The first patient had difficulty with mastication and mandibular movements, which was resolved by building a ramp on a maxillary prosthesis. The second patient had severe speech and swallowing problems, which were corrected with an acrylic, hollow speech prosthesis. In both patients the end result was satisfactory.

Adult↗