Myofascial Temporomandibular Disorders at a Turning Point

Zagury, Julyana Gomes; Ananthan, Sowmya; Quek, Samuel Y.P.; Subramanian, Gayathri

doi:10.1016/j.cden.2022.12.003

Cited by 4 publications

(2 citation statements)

References 68 publications

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“…The mechanism of action of BoNTA, and its impact on skeletal muscle function and shape, has gained attention in clinical dentistry to manage pathological and aesthetic craniofacial conditions [11]. Temporomandibular disorders (TMDs) are the most prevalent musculoskeletal diseases that affect the masticatory system, compromising vital functions such as mastication and speaking at physical and psychosocial levels [12][13][14], and reach as high as 31% in the adult population [15]. Furthermore, due to the COVID-19 pandemic, there was an increase in the prevalence of TMDs among patients affected by this respiratory disease [16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Importantly, public health strategies to control COVID-19 spread, such as the use of surgical masks by the overall population, may impact the electromyographic activity of masticatory muscles such as the masseter and the temporalis, with differences between healthy patients and those affected by TMDs [18]. In particular, electromyography of masticatory muscles has been proposed as a potential diagnostic tool to identify painrelated TMDs such as myofascial pain [13]. Thus, considering the benefits of managing painful TMDs for the oral health-related quality of life, there is interest in implementing effective and safe interventions in this context [19].…”

Section: Introductionmentioning

confidence: 99%

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Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice

Balanta-Melo,

Eyquem-Reyes,

Blanco

et al. 2023

IJMS

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Mice are commonly used to study mandibular dynamics due to their similarity in chewing cycle patterns with humans. Adult mice treated unilaterally with botulinum toxin type A (BoNTA) in the masseter exhibit atrophy of this muscle characterized by an increase in the gene expression of atrophy-related molecular markers, and a reduction in both muscle fiber diameter and muscle mass at 14d. However, the impact of this muscle imbalance on the non-treated masticatory muscles remains unexplored. Here, we hypothesize that the unilateral masseter hypofunction leads to molecular and 3D morphometric signs of atrophy of the masseter and its agonist masticatory muscles in adult mice. Twenty-three 8-week-old male BALB/c mice received a single injection of BoNTA in the right masseter, whereas the left masseter received the same volume of saline solution (control side). Animals were euthanized at 2d, 7d, and 14d, and the masticatory muscles were analyzed for mRNA expression. Five heads were harvested at 14d, fixed, stained with a contrast-enhanced agent, and scanned using X-ray microtomography. The three-dimensional morphometric parameters (the volume and thickness) from muscles in situ were obtained. Atrogin-1/MAFbx, MuRF-1, and Myogenin mRNA gene expression were significantly increased at 2 and 7d for both the masseter and temporalis from the BoNTA side. For medial pterygoid, increased mRNA gene expression was found at 7d for Atrogin-1/MAFbx and at 2d–7d for Myogenin. Both the volume and thickness of the masseter, temporalis, and medial pterygoid muscles from the BoNTA side were significantly reduced at 14d. In contrast, the lateral pterygoid from the BoNTA side showed a significant increase in volume at 14d. Therefore, the unilateral hypofunction of the masseter leads to molecular and morphological signs of atrophy in both the BoNTA-injected muscle and its agonistic non-injected masticatory muscles. The generalized effect on the mouse masticatory apparatus when one of its components is intervened suggests the need for more clinical studies to determine the safety of BoNTA usage in clinical dentistry.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice

Balanta-Melo,

Eyquem-Reyes,

Blanco

et al. 2023

IJMS

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Ultrasonographic characteristics of masseter muscle myalgia: a comparative study

De Nordenflycht,

Molinari,

Soto

et al. 2024

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology

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β₂‐adrenergic receptor activation decreases the mechanical sensitivity of rat masticatory muscle afferent fibres

Cairns,

2024

J of Oral Rehabilitation

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BackgroundActivation of β2 adrenergic receptors reduces cutaneous mechanical pain thresholds in rats. While β2 adrenergic receptor activation may contribute to mechanisms that underlie temporomandibular joint pain, its effect on masticatory muscle pain sensitivity is uncertain.ObjectivesThe current study sought to determine the extent to which β adrenergic receptors are expressed by masticatory muscle afferent fibres, and to assess the effect of local activation of these receptors on the mechanical sensitivity of masticatory muscle afferent fibres in rats.MethodsTrigeminal ganglion neurons that innervate the rat (n = 12) masseter muscle and lower lip were identified by tissue injection of fluorescent dyes and were then stained with antibodies against β1 or β2 adrenergic receptors. Extracellular recordings from 60 trigeminal ganglion neurons that innervate the masticatory muscle were undertaken in a second group of anaesthetised rats of both sexes (n = 37) to assess afferent mechanical activation thresholds. Thresholds were assessed before and after injection of the β adrenergic receptor agonists into masticatory muscle.Resultsβ1 and β2 adrenergic receptor expression was greater in labial skin than in masticatory muscle ganglion neurons (p < .05, one‐way ANOVA, Holm–Sidak test). There was a higher expression of β2 adrenergic receptors in masticatory muscle ganglion neurons in males than in females. The mixed β agonist isoproterenol increased afferent mechanical activation threshold in male but not female rats (p < .05, Mann–Whitney test). In male rats, salbutamol, a β2 selective agonist, also increased afferent mechanical activation threshold but hydralazine, a vasodilator, did not (p < .05, Mann–Whitney test).ConclusionActivation of β2 adrenergic receptors decreases the mechanical sensitivity of masticatory muscle afferent fibres in a sex‐related manner.

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Myofascial Temporomandibular Disorders at a Turning Point

Cited by 4 publications

References 68 publications

Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice

Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice

Ultrasonographic characteristics of masseter muscle myalgia: a comparative study

β₂‐adrenergic receptor activation decreases the mechanical sensitivity of rat masticatory muscle afferent fibres

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Myofascial Temporomandibular Disorders at a Turning Point

Cited by 4 publications

References 68 publications

Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice

Unilateral Hypofunction of the Masseter Leads to Molecular and 3D Morphometric Signs of Atrophy in Ipsilateral Agonist Masticatory Muscles in Adult Mice

Ultrasonographic characteristics of masseter muscle myalgia: a comparative study

β2‐adrenergic receptor activation decreases the mechanical sensitivity of rat masticatory muscle afferent fibres

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Product

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β₂‐adrenergic receptor activation decreases the mechanical sensitivity of rat masticatory muscle afferent fibres