Masticatory muscle hypertrophy (MMH) is a rare clinical phenomenon of uncertain etiology, characterized by a soft swelling near the angle of the jaw. This abnormal enlargement of the masseter muscle can alter the facial profile, leading to aesthetic concerns. Moreover, MMH may also have significant functional repercussions, including pain in the masseter region, often associated with temporomandibular disorders, fatigue, and discomfort during mastication. Non-conservative approaches offer an effective and minimally invasive solution by inducing localized muscle relaxation and reducing hypertrophy. Botulinum neurotoxin type A (BoNT/A) represents a therapeutic option for managing MMH, considering that injections can effectively reduce the masseter muscle volume, improving both facial aesthetics and related symptoms. Currently, the standard non-surgical management of MMH is BoNT/A injections, although consensus on the average dosage has not been definitely reached; on the other hand, there are data available in the literature about the injection technique of BoNT/A for lower face contouring. Therefore, the present comprehensive review aimed at exploring in detail the role of BoNT/A in the treatment of masseter muscle hypertrophy, describing its mechanism of action, the administration protocols, the clinical effects, and any side effects.
- MeSH
- Botulinum Toxins, Type A * therapeutic use administration & dosage MeSH
- Hypertrophy drug therapy MeSH
- Humans MeSH
- Masseter Muscle * drug effects pathology abnormalities MeSH
- Neuromuscular Agents therapeutic use MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
This longitudinal study was aimed to evaluate the electromyographic activity (EMG) of the masticatory muscles during mandibular tasks in women with grade II and III obesity, who were eligible for bariatric surgery. Twenty-one patients were followed up for 3 and 6 months after the Roux-en-Y gastric bypass. The EMG included analyses of the masseter and temporalis muscles during rest, right and left laterality, protrusion, and dental clenching at maximal voluntary contraction with and without parafilm. Data were tabulated and submitted for statistical analysis using the repeated measures test (P<0.05) with the Bonferroni post-test. Significant differences were observed between the right temporal muscle during maximal voluntary contraction (P=0.003) and maximal voluntary contraction with Parafilm M for the right masseter (P=0.01), left masseter (P=0.03), right temporal (P=0.002), and left temporal (P=0.03) muscles. There was gradual decrease in the resting EMG of the masticatory muscles 6 months after surgery. There was an increase in the EMG of the muscles that are the most active in the neuroanatomical movements of laterality and protrusion 6 months after surgery. There was an increase in EMG in maximal voluntary contraction with and without parafilm, 3 and 6 months after surgery. This study suggests that women with severe obesity who underwent bariatric surgery had better functional results of the masticatory muscles 3 and 6 months after the procedure, which is an important parameter in surgical planning, functional recovery, and nutritional status.
- MeSH
- Bariatric Surgery methods MeSH
- Adult MeSH
- Electromyography * methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Longitudinal Studies MeSH
- Obesity, Morbid surgery physiopathology MeSH
- Masseter Muscle * physiopathology MeSH
- Temporal Muscle * physiopathology MeSH
- Obesity physiopathology surgery MeSH
- Muscle Contraction physiology MeSH
- Gastric Bypass methods MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Rheumatoid arthritis and osteoarthritis both affect the articular cartilage, and are characterized by signs and symptoms that can affect the functions of the human body. This cross-sectional observational study evaluated electromyographic activity in the masseter and temporalis muscles, molar bite force, and mandibular mobility in adult women with rheumatoid arthritis or osteoarthritis. A total of 42 women were distributed into 3 groups: rheumatoid arthritis group (ARG, n=14); osteoarthritis group (OAG, n=14); and a healthy control group (CG, n=14). Electromyography was used to evaluate mandibular tasks at rest, right and left laterality, protrusion, and dental clenching during maximum voluntary contraction, with and without parafilm, and a dynamometer was used to analyse the right and left molar bite forces. A digital caliper was used to measure the range of mandibular movement for maximum mouth opening, right and left laterality, and protrusion. Statistical analyses were performed, including analysis of variance and Tukey's test (P<0.05). Electromyography showed no significant differences between the groups when evaluating the masticatory muscles during the mandibular tasks. Significant difference was observed between the ARG and CG, however, in the maximum right (P=0.007) and left (P=0.02) molar bite forces. Significant difference was observed in the maximum mouth opening of the ARG and OAG groups compared with that of the CG (P=0.009), suggesting that adult women with rheumatoid arthritis or osteoarthritis experience functional alterations in the stomatognathic system, particularly in molar bite force and maximum mouth opening.
- MeSH
- Adult MeSH
- Electromyography * MeSH
- Middle Aged MeSH
- Humans MeSH
- Mandible physiopathology MeSH
- Masseter Muscle physiopathology MeSH
- Temporal Muscle physiopathology MeSH
- Osteoarthritis * physiopathology diagnosis MeSH
- Cross-Sectional Studies MeSH
- Arthritis, Rheumatoid * physiopathology MeSH
- Aged MeSH
- Bite Force * MeSH
- Case-Control Studies MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Observational Study MeSH
Objective: To discover the extent of the connection between occlusal plane asymmetry and the rest tone of the four muscle groups of the orofacial region with temporomandibular joint pathology.Methods: Eighty-seven subjects were divided into two groups. The following methods were applied: clinical examination, roentgenological examination, and electromyography. Data were evaluated and statistically analyzed.Results: The variability of occlusal plane inclination in relation to the porion plane was 0-4.6o.The tonus of masseter muscle was higher in the experimental group: 1.45 mV more than in the control group: 1.23 mV (p < 0.05).Conclusion: Asymmetry of the occlusal plane inclination was found for nearly all subjects in both groups. It can be compensated for by adaptation mechanisms and does not cause temporomandibular joint disorders. Undertaken research shows the existence of a proven correlation between TMJ disorders and the resting tonus of the masseter muscle.
BACKGROUND: The recovery of the spontaneous smile has become a primary focus in facial reanimation surgery and its major determinant is the selected neurotizer. We aimed to compare the spontaneity outcomes of the most preferred neurotization methods in free functional muscle transfer for long-standing facial paralysis. METHODS: The Embase, Ovid Medline, and PubMed databases were queried with 21 keywords. All clinical studies from the last 20 years reporting the postoperative spontaneity rate for specified neurotization strategies [cross-face nerve graft (CFNG), contralateral facial nerve (CLFN), motor nerve to the masseter (MNM), and dual innervation (DI)] were included. A meta-analysis of prevalence was performed using Freeman-Tukey double arcsine transformation, I2 statistic, and generic inverse variance with a random-effects model. Risk Of Bias In Non-randomized Studies of Interventions and Newcastle-Ottawa scale were used to assess bias and study quality. RESULTS: The literature search produced 2613 results and 473 unique citations for facial reanimation. Twenty-nine studies including 2046 patients were included in the systematic review. A meta-analysis of eligible data (1952 observations from 23 studies) showed statistically significant differences between the groups (CFNG: 0.94; 95% confidence interval [CI], 0.76-1.00, CLFN: 0.91; 95% CI, 0.49-1.00, MNM: 0.26; 95% CI, 0.05-0.54, DI: 0.98; 95% CI, 0.90-1.00, P < 0.001). In pairwise comparisons, statistically significant differences were found between MNM and other neurotization strategies (P < 0.001 in CFNG compared with MNM, P = 0.013 for CLFN compared with MNM, P < 0.001 for DI compared with MNM). CONCLUSIONS: DI- and CLFN-driven strategies achieved the most promising outcomes, whereas MNM showed the potential to elicit spontaneous smile at a lower extent. Our meta-analysis was limited primarily by incongruency between spontaneity assessment systems. Consensus on a standardized tool would enable more effective comparisons of the outcomes.
- MeSH
- Facial Paralysis * surgery MeSH
- Humans MeSH
- Masseter Muscle innervation MeSH
- Nerve Transfer * methods MeSH
- Facial Nerve surgery MeSH
- Smiling physiology MeSH
- Facial Expression MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Meta-Analysis MeSH
- Systematic Review MeSH
Intervertebral disc degeneration is a pathological condition associated with the intervertebral disc and is related to functional alterations in the human body. This study aimed to evaluate the maximum molar bite force and masseter and temporal muscles thickness in individuals with intervertebral disc degeneration. Thirty-two individuals were divided into two groups: those with degeneration of intervertebral discs (n=16) and those without degeneration (n=16). The maximum molar bite force (on the right and left sides) was measured using a dynamometer. Masseter and temporal muscle thickness during mandibular task rest and dental clenching in maximum voluntary contraction were analysed using ultrasound. Significant differences in the left molar bite force (p=0.04) were observed between the groups (Student's t-test, p<0.05). The intervertebral disc degeneration group had a lower maximum molar bite force. No significant differences in muscle thickness were observed between the masseter and temporal muscles in either group. However, based on clinical observations, the group with intervertebral disc degeneration presented less masseter muscle thickness and greater temporal muscle thickness in both mandibular tasks. Degenerative disease of the intervertebral discs promoted morphofunctional changes in the stomatognathic system, especially in maximum molar bite force and masticatory muscle thickness. This study provides insight into the interaction between spinal pathology and the stomatognathic system, which is important for healthcare professionals who treat patients with functional degeneration.
- MeSH
- Intervertebral Disc Degeneration * MeSH
- Electromyography MeSH
- Humans MeSH
- Masseter Muscle diagnostic imaging MeSH
- Temporal Muscle * MeSH
- Bite Force MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Musculus masseter je párový čtyřhranný vícezpeřený masivní žvýkací sval, rozepjatý od jařmového oblouku po úhel a dolní části ramene dolní čelisti. Má zásadní význam v estetice obličeje, je důležitým znakem pohlavního dimorfismu. Je to jeden z nejsilnějších žvýkacích svalů, tvořený převážně červenými svalovými vlákny. Společně s musculus pterygoideus medialis provádí elevaci mandibuly, v rámci pterygomaseterového poutka. Kromě toho se podílí na protruzi, retruzi a laterotruzi mandibuly. Hraje zásadní roli v etiopatogenezi kraniomandibulárních parafunkcí, dislokaci zlomenin mandibuly, relapsu po ortognátních operacích. Je velmi dobře vyšetřitelný palpačně i sonograficky, terapeuticky jej lze dobře ovlivnit přímými i nepřímými fyzioterapeutickými technikami.
Being composed mainly of red muscle fibers, the masseter is one of the strongest muscles of mastication. The masseter muscle is a paired, quadrangular multipennate in structure. It originates from zygomatic arch and runs to angle and lower part of the mandibular ramus. It has a crucial role in facial aesthetics representing an important sign of sexual dimorphism. The masseter helps with mandibular protrusion, retrusion and laterotrusion; together with medial pterygoid muscle it provides mandibular elevation, as a part of pterygomasseteric sling. When in dysfunction, the masseter has a crucial role in etiopathogenesis of craniomandibular parafunctions, dislocations of mandibular fractures and relapses after orthognathic surgical approaches. Examination of the masseter can be carried out by palpation and sonography. Therapeutically, the masseter can be well influenced by both direct or indirect physiotherapeutical techniques.
- MeSH
- Humans MeSH
- Masseter Muscle * anatomy & histology physiology innervation blood supply MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
The aim of this study was to evaluate the stomatognathic system of individuals with controlled systemic hypertension through comparison with a disease-free control group. Seventy individuals (44 female and 26 male) were divided into two groups: a controlled systemic hypertension (n=35) and a disease-free control (n=35). The individuals were evaluated on the basis of masticatory cycle efficiency of the value of the ensemble-averaged integrated linear envelope to the electromyographic signal of the masseter and temporalis muscles in the habitual (peanuts and raisins) and non-habitual chewing (Parafilm M); molar bite force (right and left) and ultrasound images from the bilateral masseter and temporal muscles at rest and maximum voluntary contraction. The data obtained were tabulated and submitted to statistical analysis (p<0.05). There was a significant difference between groups in the habitual (peanuts and raisins) and non-habitual (Parafilm M) chewing with reduced muscle activity to controlled systemic hypertension group. Muscle thickness occurred significant difference between groups at rest and maximum voluntary contraction of the temporalis muscles. There was no significant difference between groups in maximum molar bite force. The present study findings indicate that the controlled systemic hypertension promotes functional changes of the masticatory system, especially with respect to its masticatory efficiency and muscle thickness.
- MeSH
- Electromyography MeSH
- Hypertension * MeSH
- Humans MeSH
- Masseter Muscle MeSH
- Temporal Muscle * diagnostic imaging MeSH
- Stomatognathic System MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- MeSH
- COVID-19 complications diagnosis physiopathology MeSH
- Adult MeSH
- Diabetes Complications complications physiopathology MeSH
- Middle Aged MeSH
- Humans MeSH
- Masseter Muscle physiopathology MeSH
- Temporal Muscle physiopathology MeSH
- Facial Pain etiology physiopathology therapy MeSH
- SARS-CoV-2 isolation & purification MeSH
- Aged MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Letter MeSH
- Research Support, Non-U.S. Gov't MeSH
Sub-condylar fractures of the temporomandibular joint can be treated by an extraoral or intraoral approach. Trans-masseteric antero-parotid approach (TMAP) is an extraoral approach utilising a retromandibular incision. The authors evaluated patients' status and any complications of using TMAP from the years 2013-2017. There were 39 patients (44 fractures). When using TMAP, in 43 fractures the fragments were favourably positioned, in one case the position was compromised. Of the complications, postoperative palsy of the facial nerve was reported 6.8% - in all cases this was only temporary. Late occlusion had an equal number of complications (in 2 cases this was as a result of an infectious complication of the wound, and in 2 cases due to resorption of the proximal fragment). Muscular pain and dysfunction of the temporomandibular joint following trauma were observed consistently in 6.8% of patients. Sialocoele, a non-conforming scar, and infectious complications were observed in 4.5% of patients. TMAP allows rapid surgical performance, with a good view for perfect repositioning and fixation of fragments of sub-condylar fractures of the temporomandibular joint. The complications associated with this approach are, for the most part, temporary, the aesthetic handicap of a scar is considered by patients to be acceptable. Overall, it is possible to evaluate retromandibular TMAP as safe, and the authors recommended it for treatment of sub-condylar fractures of the mandible.
- MeSH
- Mandibular Fractures complications surgery MeSH
- Humans MeSH
- Masseter Muscle * surgery MeSH
- Parotid Gland * surgery MeSH
- Postoperative Complications * MeSH
- Mandibular Condyle surgery MeSH
- Retrospective Studies MeSH
- Temporomandibular Joint surgery MeSH
- Treatment Outcome MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
