The effect of different condylar positions on masticatory muscle electromyographic activity in humans

Hickman, D.; Cramer, Richard D.

doi:10.1016/s1079-2104(98)90392-4

Cited by 26 publications

(21 citation statements)

References 18 publications

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“…The TMJ is a complex joint and is important for occlusion and mastication [91], [92]. The position of the TMJ can influence bite strength and muscle activation [93]. The position of the TMJ along the anterior-posterior axis tends to lie closer to the plane of the tooth row in carnivorous taxa [11].…”

Section: Discussionmentioning

confidence: 99%

Virtual Reconstruction and Prey Size Preference in the Mid Cenozoic Thylacinid, Nimbacinus dicksoni (Thylacinidae, Marsupialia)

et al. 2014

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Thylacinidae is an extinct family of Australian and New Guinean marsupial carnivores, comprizing 12 known species, the oldest of which are late Oligocene (∼24 Ma) in age. Except for the recently extinct thylacine (Thylacinus cynocephalus), most are known from fragmentary craniodental material only, limiting the scope of biomechanical and ecological studies. However, a particularly well-preserved skull of the fossil species Nimbacinus dicksoni, has been recovered from middle Miocene (∼16-11.6 Ma) deposits in the Riversleigh World Heritage Area, northwestern Queensland. Here, we ask whether N. dicksoni was more similar to its recently extinct relative or to several large living marsupials in a key aspect of feeding ecology, i.e., was N. dicksoni a relatively small or large prey specialist. To address this question we have digitally reconstructed its skull and applied three-dimensional Finite Element Analysis to compare its mechanical performance with that of three extant marsupial carnivores and T. cynocephalus. Under loadings adjusted for differences in size that simulated forces generated by both jaw closing musculature and struggling prey, we found that stress distributions and magnitudes in the skull of N. dicksoni were more similar to those of the living spotted-tailed quoll (Dasyurus maculatus) than to its recently extinct relative. Considering the Finite Element Analysis results and dental morphology, we predict that N. dicksoni likely occupied a broadly similar ecological niche to that of D. maculatus, and was likely capable of hunting vertebrate prey that may have exceeded its own body mass.

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Section: Discussionmentioning

confidence: 99%

Virtual Reconstruction and Prey Size Preference in the Mid Cenozoic Thylacinid, Nimbacinus dicksoni (Thylacinidae, Marsupialia)

et al. 2014

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“…Biteforces used in previous studies varied from maximum or 'bite hard', 8 'firmly', 9,10 'moderate', 11 to 'comfortable' 12 or 'swallowing force'. 13 Williamson et al, 5 showed that there was no significant difference in superior condyle placement when an LG was used with different bite-forces, from 'biting easy' to 'biting hard'.…”

Section: Introductionmentioning

confidence: 99%

The influence of the leaf gauge and anterior jig on jaw muscle electromyography and condylar head displacement: a pilot study

Santosa¹,

Azizi²,

Whittle³

et al. 2006

Australian Dental Journal

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Background: A leaf gauge and an anterior jig may be used to assist the recording of a reproducible jaw position for restorative and prosthodontic treatment. This study investigated possible condylar displacement using an opto-electronic jaw-tracking device and a leaf gauge or anterior jig. The effect of a leaf gauge and anterior jig on jaw muscle electromyography was also examined. Methods: Five healthy adults without symptoms of temporomandibular disorders were selected. Condylar displacement during clenching were recorded simultaneously with electromyographic activity of superior and inferior heads of the lateral pterygoid, anterior and posterior temporalis, masseter, and suprahyoid muscles. Subjects were trained to bite at maximum and half-maximum biteforce using an anterior jig incorporating a force transducer. Results: No consistent condylar displacement was observed in x, y and z axes between different biteforces although there was a trend towards superior displacement. Comparison of maximum intercuspal clench and maximum clench on a leaf gauge and an anterior jig produced significant decrease in anterior temporalis activity (p<0.05), whilst an anterior jig with maximum clench significantly decreased posterior temporalis muscle activity. Conclusion: Within the limits of this pilot study, no consistent change in condylar position was identified with these appliances.Key words: Leaf gauge, recording technique, EMG, lateral pterygoid muscle.Abbreviations and acronyms: AJ = anterior jig; CT = computer tomography; EMG = electromyographic; IHLP = inferior head of lateral pterygoid; IP = intercuspal position; LG = leaf gauge; MIPT = mid-incisal point; SHLP = superior head of lateral pterygoid; TMD = temporomandibular disorders; TMJ = temporomandibular joint.

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“…Crawford (18) showed condylar position to be strongly correlated with TMD symptomatology. Numerous studies investigated CR–CO differences (19–24). It is generally accepted that in most individuals CO is anteroposteriorly 1–2 mm away from CR (25, 26).…”

Section: Introductionmentioning

confidence: 99%

Comparison of deep bite and open bite cases: normative data for condylar positions, paths and radiographic appearances

Ari-Demirkaya

Biren

Ozkan

et al. 2004

J of Oral Rehabilitation

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To compare normal overbite, deep bite and open bite cases with clinically healthy temporomandibular joints (TMJ) regarding the difference between condylar positions in centric relation (CR) and habitual or centric occlusion (CO), condylar paths and radiographic findings of condylar appearance in order to establish normative data. Three study groups of normal overbite, deep bite and open bite cases consisted each of 30 subjects with no detectable clinical signs of temporomandibular disorder. The CR-CO differences and axiographic tracings were recorded using the School Artikulator of Mack (SAM) diagnostic system. Condylar shape was evaluated on panoramic radiographs. The CR-CO differences were greater in the vertical plane in open bite cases, and direction of movements from CR to CO showed great variability. Open bite cases had significantly shorter condylar paths. Radiographic findings exhibited that 23% of the total sample showed evidence of erosion and 83% evidence of flattening of condyles. The erosion rates were higher in the open bite group, but flattening was seen more often in the deep bite group. Results of this study showed that open bite cases show larger vertical CR-CO slides and, shorter protrusion paths than normal and deep overbite cases. The radiographic appearance of condyles in non-patients may also differ significantly according to vertical incisor guidance type. Deep bite cases demonstrated a higher incidence of condylar flattening. This study indicates that the clinician should be paying special attention to the TMJ status of open bite patients.

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The effect of different condylar positions on masticatory muscle electromyographic activity in humans

Cited by 26 publications

References 18 publications

Virtual Reconstruction and Prey Size Preference in the Mid Cenozoic Thylacinid, Nimbacinus dicksoni (Thylacinidae, Marsupialia)

Virtual Reconstruction and Prey Size Preference in the Mid Cenozoic Thylacinid, Nimbacinus dicksoni (Thylacinidae, Marsupialia)

The influence of the leaf gauge and anterior jig on jaw muscle electromyography and condylar head displacement: a pilot study

Comparison of deep bite and open bite cases: normative data for condylar positions, paths and radiographic appearances

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