Showing papers on "Bite force quotient published in 1998"

The variability of bite force measurement between sessions, in different positions within the dental arch.

Abstract: The effect of measuring bite force with different patterns of transducer on different occasions was studied. Maximum voluntary bite force was measured in eight volunteers. Three transducer positions, each with a different pattern of transducer, were used; between the anterior teeth, between the second premolar and the first molar on one side and between the second premolars and first molars on both sides. Visual feedback of force was provided. Two sets of five maximum clenches were recorded with a rest period in between. This sequence was repeated for each transducer and the experiment was repeated on three different days. The highest forces were measured with the bilateral posterior transducer (mean 580 N, s.d. 235) and the lowest on the anterior transducer (mean 286 N, s.d. 164). The standard deviations of the bite force mean values were used as an indication of the variability and were subjected to a non-parametric anova (Kruskal-Wallis). The forces recorded with each transducer position were significantly different between the transducers (P or = 0.05) when measured in the same position within the dental arch, whichever of the three positions that may be.

Bite Forces with Mandibular Implant-retained Overdentures

Abstract: Sensitivity or pain of the mucoperiosteum covering the mandibular edentulous ridge is often thought to limit bite forces in complete-denture wearers. Therefore, bite forces with mandibular implant-retained overdentures may depend on the degree of implant support. This study analyzed the effects of different degrees of support for the mandibular denture on bite forces measured four years after denture treatment as part of a randomized controlled clinical trial. All subjects had received new maxillary dentures and (1) mainly implant-borne overdentures on a transmandibular implant (TMI), (2) mucosa-borne overdentures on two cylindric permucosal IMZ implants, or (3) new conventional dentures in the mandible. Fifty-three women and 15 men (mean age, 59.1 yrs; range, 41 to 77) participated in this trial. Both unilateral and bilateral bite forces were recorded at different positions with a miniature strain gauge transducer and a mechanical bite fork, respectively. The subjects were asked to bite at three force levels. Results indicated that women had significantly lower maximum bite forces than men. Persons with mandibular implant-retained overdentures had significantly higher unilateral and bilateral maximum bite forces than complete-denture wearers. However, bite forces did not differ between the mainly implant-borne (TMI) and mucosa-implant-borne (IMZ) implant systems. Therefore, it appears that differences in support for the mandibular overdenture by dental implants are not reflected in bite force capabilities.

Mandibular corpus strain in primates : further evidence for a functional link between symphyseal fusion and jaw-adductor muscle force

Abstract: Previous work indicates that compared to adult thick-tailed galagos, adult long-tailed macaques have much more bone strain on the balancing-side mandibular corpus during unilateral isometric molar biting (Hylander [1979a] J. Morphol. 159:253-296). Recently we have confirmed in these same two species the presence of similar differences in bone-strain patterns during forceful mastication. Moreover, we have also recorded mandibular bone strain patterns in adult owl monkeys, which are slightly smaller than the galago subjects. The owl monkey data indicate the presence of a strain pattern very similar to that recorded for macaques, and quite unlike that recorded for galagos. We interpret these bone-strain pattern differences to be importantly related to differences in balancing-side jaw-adductor muscle force recruitment patterns. That is, compared to galagos, macaques and owl monkeys recruit relatively more balancing-side jaw-adductor muscle force during forceful mastication. Unlike an earlier study (Hylander [1979b] J. Morphol. 160:223-240), we are unable to estimate the actual amount of working-side muscle force relative to balancing-side muscle force (i.e., the W/B muscle force ratio) in these species because we have no reliable estimate of magnitude, direction, and precise location of the bite force during mastication. A comparison of the mastication data with the earlier data recorded during isometric molar biting, however, supports the hypothesis that the two anthropoids have a small W/B jaw-adductor muscle force ratio in comparison to thick-tailed galagos. These data also support the hypothesis that increased recruitment of balancing-side jaw-adductor muscle force in anthropoids is functionally linked to the evolution of symphyseal fusion or strengthening. Moreover, these data refute the hypothesis that the recruitment pattern differences between macaques and thick-tailed galagos are due to allometric factors. Finally, although the evolution of symphyseal fusion in primates may be linked to increased stress associated with increased balancing-side muscle force, it is currently unclear as to whether the increased force is predominately vertically directed, transversely directed, or is a near equal combination of these two force components (cf. Ravosa and Hylander [1994] In Fleagle and Kay [eds.]: Anthropoid Origins. New York: Plenum, pp. 447-468).

Self-assessed masticatory ability in relation to maximal bite force and dental state in 80-year-old subjects.

Abstract: By means of a questionnaire, clinical examination and force recordings, the relationships between self-assessed masticatory ability, dental state and bite force were studied in 160 80-year-old persons, 74 men and 86 women. The subjects were in general satisfied with their masticatory ability and 70% had no problems, while 6% reported three or more problems with mastication. Half of the subjects were dentate without removable prostheses and almost one-third had 20 or more natural teeth. The edentulous persons (about one-fifth of all) reported more problems related to mastication than the other dentition groups. The maximal bite force varied much and exhibited a significant correlation to the number of remaining teeth and dental state. The self-assessed masticatory ability was only weakly correlated with dental state and bite force. It was concluded that many subjects with few or no remaining teeth and/or removable dentures had only few complaints of impaired masticatory function and showed a good adaptation to an impaired dental status and small maximal bite force.

Three-dimensional force measurements with mandibular overdentures connected to implants by ball-shaped retentive anchors. A clinical study.

Abstract: The purpose of this in vivo study was to determine maximum and functional forces simultaneously in three dimensions on mandibular implants supporting overdentures. The anchorage system for overdenture connection was the ball-shaped retentive anchor. Five edentulous patients, each with two mandibular ITI implants, were selected as test subjects. A novel miniaturized piezo-electric force transducer was developed for specific use with ITI implants. Force magnitudes and directions were registered under various test conditions by means of electrostatic plotter records. The test modalities were maximum biting in centric occlusion, maximum biting on a bite plate, grinding, and chewing bread. Maximum forces measured in centric occlusion and on the ipsilateral implant when using a bite plate were slightly increased in vertical and backward-forward dimension (z-, y-axis) compared to the lateral-medial direction (x-axis). On the contralateral implant, equally low values were found in all three dimensions. This may be the effect of a nonsplinted anchorage device. With the use of a bite plate, force magnitudes on the ipsilateral implant were significantly higher on the z- and y-axis than mean maximum forces in centric occlusion (P < .001). Chewing and grinding resulted in lower forces compared to maximum biting, particularly in the vertical direction. The transverse force component in backward-forward direction, however, reached magnitudes that exceeded the vertical component by 100% to 300% during chewing function. This chewing pattern had not been observed in previous investigations with bars and telescopes, and therefore appears to be specific for retentive ball anchors. The prevalent or exclusive force direction registered on both implants in the vertical direction was downward under all test conditions. In the transverse direction during maximum biting the forward direction was more frequently registered, while no obvious prevalence of transverse force direction was observed during chewing and grinding.

Evaluation of prosthodontic treatment by occlusal force distribution: a methodological study.

Abstract: This study describes a new method to apply bite force measurement as an objective evaluation prosthodontic treatment. The occlusal load centre, i.e. the centre of balance of distributed occlusal force on the dentition is used as an index of bite force. The digitised image of the occlusal load centre was superimposed on the digitised image of a standardised maxillary cast. The measurement error for superimposition was small and the method was found to be useful to record and store an objective evaluation of prosthodontic treatment and masticatory function.

Reproducibility of maximal bite force distribution over dentition

Abstract: We have reported that the analysis of the maximal bite force distribution over dentition was available for objective evaluation of prosthodontic treatment. The purpose of this study was to investigate the reproducibility of occlusal force disrtribution in maximal voluntary clenching. The maximal bite forces of 10 normal subjects with complete dentition were measured at close to intercuspation using Dental Prescale System. The measurements were performed two times with an interval of 3 years. The differences of the distributed occlusal force and the location of occlusal load center, i. e., the center of balance of distributed occlusal force, between 1st and 2nd measurement were evaluated by Mann-Whitney signed rank test (p<0.01) . The coefficient of variance was calculated from the results of two measurements in order to assess the measurement error.The statistical significant differences were not found in all measurement protocol and the coefficient of variance of the location of occlusal load center showed a remarkably small value (4.0%) . The mean of absolute differences in the location of occlusal load center between two measurements were almost 4.0 mm anteroposteriorly and right-left.These results suggested that the maximal bite force measurement and the analysis of occlusal force distribution using Dental Prescale System were useful for the longitudinal evaluation of masticatory function and prosthodontic treatment. The analysis of occlusal load center was shown to be the most reliable method for evaluation. The reliable range for the reproducibility of occlusal load center was also shown.

The Riddle of the Large Loss in Bite Force after Fast Jaw-closing Movements

Abstract: In unloading experiments (in which the resistance to a forceful static bite is suddenly removed), it is shown that the residual bite force (when the jaw system is arrested shortly after the unloading) is remarkably small. For example, of a 100-N initial bite force, only 18 N is left after a jaw travel distance of 5.0 mm. The present experiments were designed to study whether the magnitude of the low residual bite force is dependent on the initial bite force, the initial degree of mouth opening, and the distance of jaw travel. Furthermore, we analyzed whether the low magnitude of the residual force can be attributed to reflex events of the jaw muscles or to the force-length properties of the jaw-closing muscles. It was found that the residual forces are largely dependent on the distance of jaw travel and are barely sensitive to variations in initial mouth-opening. The relative residual forces are independent of the magnitude of the initial bite force. The maximum residual forces are on the order of 25% of ...

Comparative study of craniofacial morphology and bite force in Fijians and Japanese

Abstract: An anthropological survey was conducted in Fiji in 1994 and 1995 to study dental arch form, craniofacial morphology, and bite force of Fijians. Measurements were obtained from dental casts, cephalograms, and thin pressure-sensitive sheets (Dental Prescale®) for bite force analysis. Results were compared with those of Japanese. In every direction, the size of the dental arch in Fijians was larger than in Japanese. Fijians displayed longer palates, longer mandibles, and bimaxillary protrusion. There was no significant difference in upper and lower facial heights. FH to lower incisor angle in Fijians was significantly larger than in Japanese. Fijians were characterized by a small palatal plane angle, occlusal plane angle and mandibular plane angle, and were thus brachyfacial. The Japanese tended to be more dolichofacial. The distances from the Cd line to the pterygoid muscles, masseter muscles, and teeth in Fijians were significantly longer than in Japanese. Occlusal contact areas of Fijians were also greater than those of Japanese. The results indicate that the masticatory muscles and craniofacial morphologies supporting them would be better integrated in Fijians than in Japanese. Am. J. Hum. Biol. 10:63-72, 1998. © 1998 Wiley-Liss, Inc.

Study of Bite Force during Sleep Associated Bruxism.

Abstract: Nocturnal bite force during sleep associated bruxism was measured in ten subjects. Hard acrylic dental appliances were fabricated for each subject's upper and lower jaws. Miniature strain-gauge transducers were mounted on the right and left sides in the first molar regions of the upper dental appliance. Thin metal plates that contact strain-gauge transducers were also attached to the lower dental appliance. Nocturnal bite force was measured for three nights at each subject's home after one-week familiarization of these appliances. Bite force signals were obtained with dynamic data logger, and then transferred to a computer. In this study, we defined bruxism event by using the following criteria: 1) Elevations of bite force signal above 5 kgf were selected as bruxism events; 2) When the inter-events interval was equal to or less than 2 seconds, these events were linked and treated as a single event ; and 3) When the duration of the event was less than 2 seconds, the event was rejected.Four hundred ninety-nine bruxism events that satisfied the above criteria were selected from recordings for a total of 30 nights. The maximum voluntary bite force during the daytime was also measured with this system. The mean amplitude of detected bruxism events was 22.5 kgf (s.d. 13.0 kgf), and the mean duration was 7.1 sec (s.d. 5.3 sec). The mean amplitude of the highest nocturnal bite force in individual subjects was 42.3 kgf (range 15.6-81.2 kgf). The mean maximum voluntary bite force during the daytime was 79.0 kgf (range 51.8-99.7 kgf) and the mean ratio of nocturnal/daytime maximum bite force was 53.1%(range 17.3-111.6%). These data suggested that nocturnal bite force during bruxism can exceed the amplitude of maximum voluntary bite force during the daytime.

Comparative in vivo and in vitro studies on the biomechanics of maxillary partial dentures. A methodological and experimental study.

Abstract: Biomechanical aspects are generally agreed to be significant, particularly during the planning of restorative treatments and the design of prosthetic appliances. However, comparative in vivo/in vitro studies show wide differences in the magnitudes and patterns of functional strains in prosthetic devices. The general aim of this study was to investigate some aspects of the biomechanical behavior of maxillary partial dentures in vivo and in vitro. This study also verified the validity, precision and accuracy of in vivo reflection photoelasticity and bite force sensors based on force sensing resistors. Conical crown retained dentures of 7 subjects were prepared for reflection photoelasticity and strain gauge recordings. Three in vitro models with simple, intermediate and advanced anatomical simulation features were manufactured for each subject. In vivo and in vitro loading experiments were performed using bite force sensors. Several variables were tested in this study such as the occlusal loading position, sex, distribution of abutment teeth, palatal height index, in vitro models, and denture structural design. The results indicate that the bite force sensor was able to accurately detect bite force levels in the range of 50 N to 300 N. The bite forces registered with the new sensor were dependent on the loading position, sex and test subject. The reliability of the new sensor for submaximum bite forces was calculated to be 93%. Strain gauge results showed that the new sensor generated strain patterns of low variance during biting tests. In vivo reflection photoelasticity experiments showed that coated areas accessible to normally incident light produced valid, reliable and accurate data of the stress/strain distribution in prosthetic appliances. Comparative in vivo/in vitro data showed that all the studied models failed to reproduce the in vivo functional strain patterns. Anatomical simulation of in vitro models is insufficient to allow for accurate mechanical analyses of maxillary RPDs, therefore, only simple verifications of the strain levels in prosthetic appliances can be attained in vitro. The magnitudes and distribution of stress fields in dentures with different structural design revealed that the palatal major connector and the denture bases mucosal contacts contribute significantly to the rigidity and stability of RPDs retained by conical crowns. Patients with a high palatal height index are less dependent on major connectors for denture stability and rigidity than patients with a low palatal height index. (Less)

Influence of the location of the bite point on the electrical efficiency of human jaw elevator muscles.

Abstract: Bite force decreases as bite points change posteroanteriorly along the dentition; this raises questions about how the efficiency of the jaw elevator muscles is affected. The objective of this study was to determine the relation between bite force and the EMG/Force characteristics of the jaw elevator muscles as the bite point is changed posteroanteriorly during maximal (MVBF) and submaximal (30%MVBF) isometric clenching efforts. Seven fully dentate subjects without any history of craniomandibular dysfunction, mean age 30.8±2.4 volunteered for this study. Bilateral surface bipolar EMG activity from the superficial masseter (SM) and anterior temporal (AT) muscles was recorded simultaneously to alternate antagonistic vertical bite force measurements from the right and left first molar, first premolar, canine and anterior incisor teeth. The subjects clenched three times for 2 seconds each time to a requested level (MVC; 30%MVBF) on a force transducer. EMG/Force ratio (E/F) values for working (W) and balancing (B) muscles were calculated and normalized for each task. Statistical differences among unilateral bite points were analyzed with Two-way ANOVA. The magnitude of bite forces were similar to those proposed by other authors. Changing posteroanteriorly the bite point induced a gradual and significant (MVBF: p<0.01; 30%MVBF: p<0.001) increase of the corresponding working and balancing SM E/F values, with the latter being either the same or higher than the working ones. The E/F registered at the MVBF and 30%MVBF molar and anterior bite points were different in a proportion of 1: 2 in all subjects. At MVBF the AT's E/Fs also increased corresponding to the anteroposterior shift of the bite point (p<0.01) ; however, the 1: 2 proportion of the molar vs the anterior bite point was not observed; at 30%MVBF there was not any evident pattern, and the E/F were not significantly different among bite points. From these results it can be concluded that the EMG/Force ratio of the working and balancing superficial masseter and anterior temporal muscles is a posteroanterior increasing function and therefore has an inverse relationship with bite force, condition which may induce a negative effect in the electrical efficiency of the jaw elevator muscles.The results of this study have been previously presented at the following meetings:74th General Session of the International Association for Dental Research.20th Annual Conference of the European Prosthodontic Society.96th Meeting of the Japan Prosthodontic Society.44th Annual Meeting of the Japanese Association for Dental Research.75th General Session of the International Association for Dental Research.Annual Meeting of the Niigata Dental Association, July 1997.

The variability of bite force measurement between sessions, in different positions within the dental arch

Abstract: SUMMARY The effect of measuring bite force withdifferent patterns of transducer on differentoccasions was studied. Maximum voluntary biteforce was measured in eight volunteers. Threetransducer positions, each with a different patternof transducer, were used; between the anterior teeth,between the second premolar and the first molar onone side and between the second premolars and firstmolars on both sides. Visual feedback of force wasprovided. Two sets of five maximum clenches wererecorded with a rest period in between. Thissequence was repeated for each transducer and theexperiment was repeated on three different days.The highest forces were measured with the bilateral Introduction The measurement of bite force is often necessary toassess jaw-closing muscle function and also to comparemuscle activity between subjects in a wide variety ofexperimental situations. However, this measurement isnotoriously difficult and the reliability of the resultdepends on a number of factors, such as design andcomfort of the transducer and the position of thetransducer within the dental arch.Previous studies relating to bite strength with naturaland artificial dentitions, using different measuringdevices under varying test conditions have shown awide range of forces (for review see Hagberg, 1987). InWestern populations the average maximum bite forcebetween the molar teeth is usually reported to be inthe range of 600–750 N (Hagberg, 1987). Forces