Reverse-sequencing chewing patterns before and after treatment of children with a unilateral posterior crossbite
TL;DR: The results showed that, before therapy, the percentage of reverse-sequencing chewing cycles on the crossbite side was significantly higher than that on the normal side (P < 0.001) with both the soft and hard bolus.
Abstract: SUMMARY The aim of this study was to compare the percentage of reverse-sequencing chewing cycles in 22 children [9 boys and 13 girls; mean age ± SD, 8.6 ± 1.3 and 8.8 ± 1.5 years, respectively), with a unilateral right or left posterior crossbite, before and after therapy. The chewing cycles were recorded using a kinesiograph while the subjects masticated a soft and a hard bolus on both the crossbite and non-crossbite side. Chewing data were acquired before and 6 months after orthodontic treatment of the crossbite with an orthodontic functional appliance, the ‘ Function Generating Bite ’ . The results showed that, before therapy, the percentage of reverse-sequencing chewing cycles on the crossbite side was signifi cantly higher than that on the normal side ( P < 0.001) with both the soft and hard bolus. In addition, the percentage of reverse-sequencing chewing cycles on the crossbite side before therapy was signifi cantly greater than after therapy with both a soft and hard bolus ( P < 0.001). No signifi cant differences were found in the percentage of reverse-sequencing chewing cycles on the noncrossbite side, before or after therapy, either with a soft or hard bolus.
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TL;DR: Critically review evidence for a possible association between malocclusion, orthodontic treatment and TMD.
Abstract: Temporomandibular Disorder (TMD) is the main cause of pain of non-dental origin in the oro-facial region including head, face and related structures. The aetiology and the pathophysiology of TMD is poorly understood. It is generally accepted that the aetiology is multifactorial, involving a large number of direct and indirect causal factors. Among such factors, occlusion is frequently cited as one of the major aetiological factors causing TMD. It is well known from epidemiologic studies that TMD-related signs and symptoms, particularly temporomandibular joint (TMJ) sounds, are frequently found in children and adolescents and show increased prevalence among subjects between 15 and 45 years old. Aesthetic awareness, the development of new aesthetic orthodontic techniques and the possibility of improving prosthetic rehabilitation has increased the number of adults seeking orthodontic treatment. The shift in patient age also has increased the likelihood of patients presenting with signs and symptoms of TMD. Because orthodontic treatment lasts around 2 years, orthodontic patients may complain about TMD during or after treatment and orthodontists may be blamed for causing TMD by unsatisfied patients. This hypothesis of causality has led to legal problems for dentists and orthodontists. For these reasons, the interest in the relationship between occlusal factors, orthodontic treatment and TMD has grown and many studies have been conducted. Indeed, claims that orthodontic treatment may cause or cure TMD should be supported by good evidence. Hence, the aim of this article is to critically review evidence for a possible association between malocclusion, orthodontic treatment and TMD.
188 citations
Cites background from "Reverse-sequencing chewing patterns..."
...reverse sequence chewing pattern (50, 51) have been reported....
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TL;DR: The current knowledge regarding the importance of fiber-type diversity in masticatory muscles versus supra- and infrahyoid muscles, and versus limb and trunk muscles is discussed and new information regarding the adaptive response and specific genetic variations of muscle fibers on the functional significance of the masticatories is highlighted.
Abstract: The masticatory muscles achieve a broad range of different activities such as chewing, sucking, swallowing, and speech. In order to accomplish these duties, masticatory muscles have a unique and heterogeneous structure and fiber composition, enabling them to produce their strength and contraction speed largely dependent on their motor units and myosin proteins that can change in response to genetic and environmental factors. Human masticatory muscles express unique myosin isoforms, including a combination of thick fibers, expressing myosin light chains (MyLC) and myosin class I and II heavy chains (MyHC) -IIA, -IIX, α-cardiac, embryonic and neonatal and thin fibers, respectively. In this review, we discuss the current knowledge regarding the importance of fiber-type diversity in masticatory muscles versus supra- and infrahyoid muscles, and versus limb and trunk muscles. We also highlight new information regarding the adaptive response and specific genetic variations of muscle fibers on the functional significance of the masticatory muscles, which influences craniofacial characteristics, malocclusions, or asymmetry. These findings may offer future possibilities for the prevention of craniofacial growth disturbances.
66 citations
TL;DR: The results provide kinematic and EMG adaptations to bolus hardness in healthy subjects and can be used as normative data in the development of methods for early diagnosis of impaired chewing function.
62 citations
TL;DR: The knowledge of the periodontal mechanoreceptors is summarized, and it is concluded that they are very refined neural receptors, deeply involved in the activation and coordination of the masticatory muscles during function.
61 citations
Cites background from "Reverse-sequencing chewing patterns..."
...…may explain the so-called “reverse sequencing chewing cycles” that have been shown, with high prevalence, in posterior unilateral crossbite patients, during chewing on the crossbite side (Piancino, Bracco, Vallelonga, Merlo, & Farina, 2008; Piancino et al., 2012; Piancino et al., 2006) (Figure 7)....
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...There is evidence that the muscular activation output and coordination, during chewing on the crossbite side, is altered, being the electromyographic amplitude of the masseter of the crossbite side, significantly lower than the contralateral (Piancino et al., 2009; Piancino et al., 2006)....
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TL;DR: The results suggest that the morphology of the maxilla modulates the transmission of forces generated during mastication to the rest of the cranium by deforming less in individuals with the ability to generate proportionately larger temporalis muscle forces.
Abstract: The human skull is gracile when compared to many Middle Pleistocene hominins It has been argued that it is less able to generate and withstand high masticatory forces, and that the morphology of the lower portion of the modern human face correlates most strongly with dietary characteristics This study uses geometric morphometrics and finite element analysis (FEA) to assess the relationship between skull morphology, muscle force and cranial deformations arising from biting, which is relevant in understanding how skull morphology relates to mastication The three-dimensional skull anatomies of 20 individuals were reconstructed from medical computed tomograms Maximal contractile muscle forces were estimated from muscular anatomical cross-sectional areas (CSAs) Fifty-nine landmarks were used to represent skull morphology A partial least squares analysis was performed to assess the association between skull shape and muscle force, and FEA was used to compare the deformation (strains) generated during incisor and molar bites in two individuals representing extremes of morphological variation in the sample The results showed that only the proportion of total muscle CSA accounted for by the temporalis appears associated with skull morphology, albeit weekly However, individuals with a large temporalis tend to possess a relatively wider face, a narrower, more vertically oriented maxilla and a lower positioning of the coronoid process The FEAs showed that, despite differences in morphology, biting results in similar modes of deformation for both crania, but with localised lower magnitudes of strains arising in the individual with the narrowest, most vertically oriented maxilla Our results suggest that the morphology of the maxilla modulates the transmission of forces generated during mastication to the rest of the cranium by deforming less in individuals with the ability to generate proportionately larger temporalis muscle forces
59 citations
References
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TL;DR: It is suggested that chewing causes regional increases in brain neuronal activities which are related to biting force, and that chewing of moderately hard gum produced stronger BOLD signals than the chewing of hard gum.
Abstract: Mastication has been suggested to increase neuronal activities in various regions of the human brain. However, because of technical difficulties, the fine anatomical and physiological regions linked to mastication have not been fully elucidated. Using functional magnetic resonance imaging during cycles of rhythmic gum-chewing and no chewing, we therefore examined the interaction between chewing and brain regional activity in 17 subjects (aged 20-31 years). In all subjects, chewing resulted in a bilateral increase in blood oxygenation level-dependent (BOLD) signals in the sensorimotor cortex, supplementary motor area, insula, thalamus, and cerebellum. In addition, in the first three regions, chewing of moderately hard gum produced stronger BOLD signals than the chewing of hard gum. However, the signal was higher in the cerebellum and not significant in the thalamus, respectively. These results suggest that chewing causes regional increases in brain neuronal activities which are related to biting force.
256 citations
TL;DR: It is concluded that unilateral posterior crossbites produce morphological and positional asymmetry of the mandible in young children, and that these asymmetries can be largely eliminated with early expansion therapy.
178 citations
"Reverse-sequencing chewing patterns..." refers background or result in this paper
...( Enlow, 1986 ; Pirttiniemi et al. , 1990 , 1991 ; Lam et al. , 1999 ; Nerder et al. , 1999 ; Santos Pinto et al. , 2001 ; Gazit-Rappaport et al. , 2003 )....
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...A posterior unilateral crossbite is considered a serious asymmetric malocclusion ( Moller and Troelstrup, 1975 ; Pinto et al. , 2001 ; Bracco et al. , 2002 ; Harrison and Ashby, 2003 )....
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...…posterior crossbite exhibit unusual chewing patterns when chewing on the affected side, and this is characterized by an increased frequency of reverse sequencing ( Lewin, 1985 ; Ben-Bassat et al. , 1993 ; Brin et al. , 1996 ; Pinto et al. , 2001; Throckmorton et al. , 2001 ; Saitoh et al. , 2002 )....
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...This was expected and has been confi rmed in previous studies ( Lewin, 1985 ; Ben-Bassat et al. , 1993 ; Brin et al. , 1996 ; Pinto et al. , 2001 ; Throckmorton et al. , 2001 ; Saitoh et al. , 2002 )....
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TL;DR: The condyle path was found to be asymmetric in both the treated and untreated lateral cross-bite groups and to be steeper on the side of the diagnosed or treated cross- bite.
Abstract: The aim of this work was to examine the degree and direction of asymmetry in the condyle path, and its associations with facial and dental midline asymmetry in patients with treated and untreated unilateral cross-bite. The subjects were 22 patients, 16 female and 6 male, aged from 9 to 50 years. Nine patients had a history of treated unilateral cross-bite, the mean age of this group being 11.1 years. The children had been treated with removable or fixed expansion appliances at an age of 5-8 years. Thirteen patients had untreated unilateral cross-bite, their mean age being 23.4 years. The clinical examinations were performed by two orthodontists and standard PA roentgenograms were taken in a cephalostat. The condyle path was recorded from the inversion of a face bow fixed rigidly on the anterior mandibular teeth, the positions of the bow being first recorded with the teeth in maximal intercuspation and then in protrusion with the midline unchanged. The condyle path was found to be asymmetric in both the treated and untreated lateral cross-bite groups and to be steeper on the side of the diagnosed or treated cross-bite. The degree of asymmetry was found to be twice as great in the untreated as in the treated group. The facial asymmetry parameters describing the position of the mandible showed the strongest correlation with condyle path asymmetry. The results stress the importance of early treatment of lateral cross-bites.
162 citations
Additional excerpts
...( Enlow, 1986 ; Pirttiniemi et al. , 1990 , 1991 ; Lam et al. , 1999 ; Nerder et al. , 1999 ; Santos Pinto et al. , 2001 ; Gazit-Rappaport et al. , 2003 )....
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156 citations
Additional excerpts
...( Enlow, 1986 ; Pirttiniemi et al. , 1990 , 1991 ; Lam et al. , 1999 ; Nerder et al. , 1999 ; Santos Pinto et al. , 2001 ; Gazit-Rappaport et al. , 2003 )....
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