Posterior scissors‐bite: masticatory jaw movement and muscle activity

Tomonari, Hiroshi; Kubota, Takeshi; Yagi, Takakazu; Kuninori, Takaharu; Kitashima, Fumiaki; Uehara, Sawako; Miyawaki, Shouichi

doi:10.1111/joor.12148

Cited by 38 publications

(30 citation statements)

References 38 publications

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“…Standard 5‐g gummy jelly was specially prepared for this study. The shape of the gummy jelly was similar to that of a truncated cone (5‐g gummy jelly: height, 11 mm; top diameter, 12 mm; base diameter, 22 mm).…”

Section: Methodsmentioning

confidence: 99%

First molar cross‐bite is more closely associated with a reverse chewing cycle than anterior or pre‐molar cross‐bite during mastication

Tomonari

Ikemori

Kubota

et al. 2014

J of Oral Rehabilitation

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A posterior cross-bite is defined as an abnormal bucco-lingual relationship between opposing molars, pre-molars or both in centric occlusion. Although it has been reported that patients with unilateral posterior cross-bite often show unique chewing patterns, the relationship between the form of cross-bite and masticatory jaw movement remains unclear in adult patients. The objective of this study was to investigate masticatory jaw movement among different forms of cross-bite. One hundred and one adults were recruited in this study: 27 had unilateral first molar cross-bite (MC group); 28, unilateral pre-molar cross-bite (PC group); 23, anterior cross-bite (AC group); and 23, normal occlusion (control group). Masticatory jaw movement of the lower incisor point was recorded with six degrees of freedom jaw-tracking system during unilateral mastication. Our results showed that the reverse chewing ratio during deliberate unilateral mastication was significantly larger in the MC group than in the PA (P < 0.001), AC (P < 0.001) and control (P < 0.001) groups. These findings suggest that compared to the anterior or pre-molar cross-bite, the first molar cross-bite is more closely associated with a higher prevalence of a reverse chewing cycle.

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Section: Methodsmentioning

confidence: 99%

First molar cross‐bite is more closely associated with a reverse chewing cycle than anterior or pre‐molar cross‐bite during mastication

Tomonari

Ikemori

Kubota

et al. 2014

J of Oral Rehabilitation

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“…This depends on whether the selection of the chewing side is regulated primarily by peripheral asymmetries or is an expression of cerebral dominance, like other functional lateralities. Peripheral factors that have been found to be related to masticatory laterality include asymmetry of several characteristics of occlusion, bite force and masticatory performance, missing posterior teeth and temporomandibular disorders , most of them are interrelated . However, other studies have failed to find a significant association between some of these peripheral factors and the PCS .…”

Section: Introductionmentioning

confidence: 99%

Peripheral, functional and postural asymmetries related to the preferred chewing side in adults with natural dentition

Rovira-Lastra

Flores-Orozco

Ayuso‐Montero

et al. 2015

J of Oral Rehabilitation

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Summary The aim of this cross‐sectional study was to determine the preferred chewing side and whether chewing side preference is related to peripheral, functional or postural lateral preferences. One hundred and forty‐six adults with natural dentition performed three masticatory assays, each consisting of five trials of chewing three pieces of silicon placed into a latex bag for 20 cycles, either freestyle or unilaterally on the right‐ or left‐hand side. Occlusal contact area in the intercuspal position, maximum bite force, masticatory performance and cycle duration were measured and the lateral asymmetry of these variables was calculated. Laterality tests were performed to determine handedness, footedness, earedness and eyedness as functional preferences, and hand‐clasping, arm‐folding and leg‐crossing as postural lateral preferences. The preferred chewing side was determined using three different methods: assessment of the first chewing cycle for each trial, calculation of the asymmetry index from all cycles and application of a visual analogue scale. Bivariate relationship and multiple linear regression analyses were performed. Among unilateral chewers, 77% of them preferred the right side for chewing. The factors most closely related to the preferred chewing side were asymmetry of bite force, asymmetry of masticatory performance and earedness, which explained up to 16% of the variance. Although several functional or postural lateral preferences seem to be related to the preferred chewing side, peripheral factors such as asymmetry of bite force and of masticatory performance are the most closely related to the preferred chewing side in adults with natural dentition.

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“…Tomonari et al showed that lateral excursion on the scissors bite side was poor due to occlusal interferences in patients with unilateral posterior scissors bite. 19 In the current patient, lateral excursive jaw movements on both sides were irregular for incisor and bilateral condyle movements, and a CR-CO discrepancy was observed at initial presentation. As a result of treatment, satisfactory lateral excursive movements and CR-CO coincidence were achieved, and the maximum open-close movement was maintained.…”

Section: Discussionmentioning

confidence: 55%

Nonsurgical orthodontic treatment of a hypodivergent adult patient with bilateral posterior scissors bite and excessive overjet

Nakamura

Kawanabe

Adachi

et al. 2018

The Angle Orthodontist

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This report illustrates successful nonsurgical orthodontic treatment of a hypodivergent adult patient with bilateral posterior scissors bite (Brodie bite) and excessive overjet. A 26-year-old woman primarily reported maxillary incisor protrusion. She was diagnosed with Class ll division 1 malocclusion with skeletal Class I, short face, low mandibular plane angle and bilateral posterior scissors bite. A lingual arch with anterior bite block and posterior miniscrews with preadjusted edgewise appliances were used to improve the bilateral scissors bite. After achieving molar occlusion, the maxillary first premolars were extracted, and six miniscrews were used to improve the anterior-posterior and vertical discrepancies. After active treatment for 56 months, the convex facial profile with excessively protruded lips was improved and good interdigitation with ideal incisor relationship was achieved. Additionally, the irregular movements of the incisal path and the bilateral condyles during lateral excursion were improved. At 13 months of retention, a satisfactory facial profile, occlusion, and jaw movements were maintained. The treatment results suggest that miniscrews and fixed bite blocks were effective and efficient to facilitate correction of the bilateral scissors bite, excessive overjet, and vertical relationship correction in this nonsurgical orthodontic treatment.

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Posterior scissors‐bite: masticatory jaw movement and muscle activity

Cited by 38 publications

References 38 publications

First molar cross‐bite is more closely associated with a reverse chewing cycle than anterior or pre‐molar cross‐bite during mastication

First molar cross‐bite is more closely associated with a reverse chewing cycle than anterior or pre‐molar cross‐bite during mastication

Peripheral, functional and postural asymmetries related to the preferred chewing side in adults with natural dentition

Nonsurgical orthodontic treatment of a hypodivergent adult patient with bilateral posterior scissors bite and excessive overjet

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