Masseter Muscle Thickness Research Articles

Ultrasonographic Assessment of Masseter and Anterior Temporal Muscle Thickness and Internal Structure in Young Adult Patients With Bruxism.

The current study is a comparative cross-sectional analysis study to determine the thickness and internal structure of the masseter muscle (MM) and anterior temporal muscle (ATM) in patients with bruxism by ultrasonography (USG). A total of 100 patients (36 males, 64 females), 50 with bruxism and 50 without bruxism, aged 20-30 years were included in the study. All patients were investigated with MM and ATM USG. The thickness of the muscles was measured at rest and during clenching and the internal structure at rest was classified as Type I, II, and III. Differences in the internal structure between bruxism and non-bruxism groups were determined using the Chi-square test (p < 0.05). The most common internal structure in bruxism was Type 2 in MM (74%) and Type 1 in ATM (46%), whereas in non-bruxism, Type 1 in MM (58%) and Type 1 in ATM (80%) were found most frequently. While there was a statistically significant difference in the internal echogenic pattern in the right MM and ATM in bruxism (p < 0.05), no significant difference was observed on the left side (p > 0.05). Bruxism patients had higher rest and clench thicknesses than non-bruxism patients on both sides in MM and ATM, however, this did not result in a statistically significant difference (p > 0.05). The results obtained showed that the evaluation of internal structure and thickness differences via USG is crucial in understanding the nature of the bruxism process affecting the masseter and ATM, facilitating its clinical diagnosis and leading to its treatment.

Effects of gum chewing training on occlusal force, masseter muscle thickness and mandibular shape: A randomised controlled clinical trial.

Masticatory muscle training by chewing gum can be performed easily and improve masticatory muscle function and strength. However, increased masticatory muscle activity and function may alter the mandibular shape. We aimed to investigate the effects of gum chewing training on the occlusal force, masseter muscle thickness (MMT) and mandibular shape in healthy adults. We conducted a prospective randomised controlled trial from January 2020 to September 2020 at the Yonsei University College of Dentistry. Fifty-eight participants were randomly assigned to the training and control groups. The training group chewed gum three times a day for 6 months, while the control group received no training. Changes in the maximum occlusal force and MMT were evaluated at baseline and after 1, 3 and 6 months. Changes in the mandibular shape were evaluated at baseline and after 6 months. The mean maximum occlusal force of the training group at 3 months was significantly higher than that at baseline, which was also significantly different from that in the control group (p < .001). As the maximum occlusal force increased, the occlusal contact area also increased (p = .020). There was no statistically significant difference in MMT or mandibular shape compared to the baseline. Mastication training using gum increases maximum occlusal force due to an increase in occlusal contact area but has no effect on MMT or mandibular shape.

Hard and Soft Tissue Facial Landmarks for Mandibular Angle Reduction: A Clinical Study.

Square faces, which are influenced by genetic factors and structural features, are considered undesirable among the Asian population. Surgical interventions, such as mandibular angle reduction, aim to alter these characteristics, though complications may arise. We aimed to investigate the morphology of the mandibular angle and masseter muscle thickness using computed tomography (CT) and to analyze hard and soft tissue correlations to enhance surgical outcomes for patients with square faces. This retrospective clinical study included 100 Taiwanese patients aged 18-50 years. CT was used to analyze key clinical parameters, including bilateral mandibular width, mandibular divergence angle, ramus height, distance from the mandibular angle to the inferior alveolar nerve (IAN), and the thickness of the masseter muscle. Significant correlations were noted between the patients' physical height and weight, mandibular width, ramus height, masseter thickness, and distance from the angle to the IAN. Males exhibited a significantly longer and thicker ramus height (66.48 ± 4.28 mm), greater masseter thickness (15.46 ± 2.35 mm), and greater safety range for mandibular angle reduction surgery (18.35 ± 3.19 mm) (p < 0.00008). Significant correlations were observed among all parameters, except between mandibular width and gonial angle and the distance from the angle to the IAN and between mandibular divergence and masseter muscle thickness (p > 0.1). Our study highlighted the complex interplay among factors that contribute to square facial morphology. Careful preoperative assessments and customized surgical planning are essential for addressing this multifaceted clinical challenge.

Assessment of Reliability, Agreement, and Accuracy of Masseter Muscle Ultrasound Thickness Measurement Using a New Standardized Protocol.

There is no validated method of assessing masseter muscle thickness (MMT) by ultrasound imaging (US). However, this is important to ensure study and measurement quality of MMT by US in future studies, as MMT differs depending on the examined area. Thus, this study's aim was to present a new standardized method for assessing the MMT by US and to evaluate the reliability, consistency, and accuracy of its measurements. We also compared the results of MMT measurements obtained by US and computer tomography (CT). The study included nine healthy adults. The US and CT scans were collected in a supine rest position with the mandible in relaxed position. US measurements were determined according to a new standardized protocol (with precise probe location). The MMT measured by CT and US over a seven-day interval showed excellent intra-rater reliability. The mean MMT measured by CT was 12.1 mm (1.74) on the right side and 11.9 mm (1.61) on the left side. The mean MMT measured by US was 12.7 mm (2.00) on the right side and 11.5 mm (1.37) on the left side. The mean percent error in MMT measurement between CT and US was below 6%. A strong linear relationship was found between the CT and US measurements of the MMT on both body sides (p < 0.001, r ≥ 0.93). The proposed method of MMT measurement using US demonstrated excellent reliability, yielding results similar to those obtained from CT images. We recommend the use of this standardization protocol in further studies where precise assessment of MMT by US is expected.

Comparison between botulinum toxin type A injection on masseter muscle only and additional injection on anterior belly of digastric muscle in sleep bruxism patients: A clinical trial.

This study aims to evaluate the effects on bite force and muscle thickness of the botulinum toxin (BoNT) injection for patients with sleep bruxism (SB) by comparing injections into the masseter muscle only and both the masseter and the anterior belly of the digastric muscle (ABDM) in a clinical trial. Twelve SB patients received BoNT-A injections using US-guided techniques into the masseter muscle only (Group A), while the remaining 12 SB patients received injections into both the masseter and ABDM (Group B). Bite force and muscle thickness were measured before injection, as well as 1 and 2 months after injection. The bite force and masseter muscle thickness decreased in both Group A and Group B before injection, and at 1 and 2 months after injection. However, there was no significant difference (p > .05, repeated measures analysis of variance) between the two groups, and there was also no significant difference in ABDM thickness (p > .05, repeated measures analysis of variance). This study is the first to assess the short-term effects of BoNT injected into ABDM for SB control. Results show no influence on SB reduction, suggesting the need for further research on BoNT's effectiveness in controlling intense ABDM contractions during sleep and assessing suprahyoid muscle potential impact on rhythmic masticatory muscle activity occurrence.

Examination of the masseter muscle in patients with hemifacial microsomia using high-frequency ultrasound and shear wave elastography

BackgroundThis study aimed to prospectively investigate the reference values for masseter muscle thickness and hardness using ultrasonography and shear wave elastography, respectively, in patients with hemifacial microsomia (HFM). MethodsWe enrolled 51 patients, aged 5–20 years, with HFM including 31 males and 20 females. The upper-lower, left-right, and anterior-posterior diameters of 102 masseter muscles and stiffness of 98 masseter muscles were determined by examining the unaffected and affected sides of each participant’s face. ResultsThe upper-lower, left-right, and anterior-posterior diameters of the masseter muscle were significantly smaller at rest (4.26 ± 0.83, 2.94 ± 0.75, and- 0.80 ± 0.25 cm, respectively) and during contraction (3.95 ± 0.78, 2.71 ± 0.78, and 0.87 ± 0.29 cm, respectively) in the affected side than those in the healthy side (5.45 ± 0.66, 3.87 ± 0.49, and 0.97 ± 0.20 cm, respectively, at rest and 4.99 ± 0.45, 3.49 ± 0.53, and 1.07 ± 0.23 cm, respectively, during contraction, p < 0.05). In the resting state, the hardness of the masseter muscle on the affected side (0.77 ± 0.66 m/s) was significantly greater than that on the healthy side (0.42 ± 0.41 m/s; p < 0.05). The magnitude of changes in the upper-lower, left-right, and anterior-posterior diameters of the biting muscle in the occlusal state were significantly smaller on the affected side (−0.30 ± 0.27, −0.23 ± 0.17, and 0.08 ± 0.08 cm, respectively) than those in the healthy side (−0.47 ± 0.38, −0.37 ± 0.25, and 0.10 ± 0.12 cm, respectively, p < 0.05). ConclusionsThe knowledge of these values allows for better understanding of the disease characteristics of HFM, which may be used for its diagnosis, treatment, and prognosis. Patients experiencing different severity levels exhibited significant differences in the morphology and function of the masseter muscle on the affected-side (p < 0.05). Evidence levelLevel III.

Temporal and masseter muscle evaluation by MRI provides information on muscle mass and quality in acromegaly patients

PurposeThe impact of GH/IGF-1 levels on skeletal muscle in acromegaly is still controversial. Temporal (TMT) and masseter muscle (MMT) thickness has been recently demonstrated as a reliable measure of muscle mass. We aimed to investigate the relationship between TMT, MMT and clinical/biochemical characteristics in patients with acromegaly.MethodsSingle center retrospective longitudinal study including 69 patients with at least one available brain/sella turcica MRI and matched clinical data. TMT, MMT, and muscle fatty infiltration (modified Goutallier score) were evaluated in all patients at baseline (first available MRI) and over time (182 MRIs analyzed).ResultsAt baseline, both TMT and MMT were higher in males than females (p = 0.001 and p = 0.016, respectively). TMT and MMT were positively associated (β 0.508, p < 0.001), and they were positively correlated with IGF-1 xULN (TMT, p = 0.047; MMT, p = 0.001). MMT had a positive correlation with patients’ weight (p = 0.015) and height (p = 0.006). No correlation was found between TMT, MMT and the presence of hypogonadism. Considering all available MRIs, sex and IGF-1 xULN were significant determinants of TMT and MMT at multivariable analysis (female sex: β -0.345/-0.426, p < 0.001; IGF-1 xULN: β 0.257/0.328, p < 0.001). At longitudinal evaluation, uncontrolled patients at baseline showed a significant reduction of MMT over time (p = 0.044). Remarkable fatty infiltration was observed in 34–37% of MRIs; age was the main determinant (temporal muscle: OR 1.665; p = 0.013; masseter muscle: OR 1.793; p = 0.009).ConclusionMale patients with higher IGF-1 values have thicker temporal and masseter muscles, suggesting that sex and IGF-1 have a significant impact on muscle mass in acromegaly.

Exploring botulinum toxin’s impact on masseter hypertrophy: a randomized, triple-blinded clinical trial

The present study aimed to assess the effectiveness and functional adverse effects of a single and multiple injections of botulinum toxin A (BoNT-A) for masseter hypertrophy (MH). Twenty-six women complaining about lower third facial enlargement due to MH, received 75 U of BoNT-A (abobotulinum toxin) in each masseter muscles. After 3 months, patients were randomly assigned to receive a second treatment session of Saline Solution: (G1; n = 11) or BoNT-A: (G2; n = 12). Muscle thickness (ultrasound), electrical activity (electromyography; EMG), masticatory performance, and subjective perception of MH were evaluated. Follow-up was performed at 1, 3 and 6 months. Muscle thickness, EMG activity, and masticatory performance were analyzed using ANOVA two-way and Sidak test as post-hoc. Masticatory performance was analyzed by the Friedman’s test and Mann–Whitney test. Regarding inter-groups comparisons, there was a significant decrease in the left masseter muscle thickness in the G2 group at the 6 month follow-up (p < 0.02). For EMG, significant differences were evident at the 6 month assessment, with higher masseter activity for G1 (p < 0.05). For masticatory performance, no significant differences were observed throughout the study (p > 0.05) and a higher improvement in subjective perception of MH was observed in the 1 month follow-up for G2 (p < 0.05). In conclusion, BoNT-A is effective for MH, however multiple injections cause functional adverse effects in masseter muscle.

Morphological Changes of the Temporomandibular Joint and Masseter Muscle After Mandibular Angle Osteotomy.

Mandibular angle osteotomy with outer cortex grinding is an effective cosmetic procedure for correcting square faces. However, morphological changes in the mandible may also cause temporomandibular joint (TMJ) disorders. This retrospective study aimed to investigate the morphological stabilization of the TMJ and changes in masseter muscle thickness after mandibular angle osteotomy to evaluate the safety of the procedure. Data from patients who underwent mandibular angle osteotomy with outer cortex grinding between January 2016 and January 2019 were retrospectively reviewed. Preoperative and long-term follow-up (~1 y) computed tomography data were collected from these patients, and morphological changes in the TMJ and masseter muscle were analyzed. The results from the computed tomography data showed that the condylar length and condylar height were significantly reduced 1 year after the operation ( P < 0.05). In addition, the morphology of the TMJ was stable, and the distance between the mandibular condyle and the glenoid fossa did not change significantly. No significant difference was observed in masseter muscle thickness before and after the operation. After mandibular angle osteotomy with outer cortex grinding, the length and height of the mandibular condyle were functionally restored without any disorders of the TMJ. Moreover, the masseter muscle exhibited stable function. In conclusion, the procedure is safe for occlusal function and suitable for popularization.

Masseter muscle thickness is predictive of cancer cachexia in patients with head and neck cancer.

Cancer cachexia is prevalent in head and neck cancer patients. The L3 skeletal muscle index (SMI) is often used to assess sarcopenia and cachexia but is infrequently able to be measured in this population. Masseter muscle thickness (MT) may serve as an alternative predictor of cachexia. SMI and MT were calculated from 20 trauma (CTRL) and 40 cachectic (CA-CX) and non-cachectic (CA-NCX) head and neck cancer patients. Area Under the Curve of the Receiver Operating Characteristics (AUC-ROC) analysis was performed for SMI and MT. Both SMI and MT were significantly decreased in CA-CX patients (vs. CA-NCX mean difference -19.5 cm2/m2 and -2.06 mm, respectively) and significant predictors of CA-CX (AUC = 0.985 and 0.805, respectively). When analyzed by sex, the same findings were observed for MT in males and trended toward significance in females. Compared with SMI, MT is a good alternative prognostic biomarker to determine CA-CX status in HNC patients.

Investigation of the masseter and temporalis muscles thicknesses in individuals with and without temporomandibular disorders by ultrasonography: A randomized controlled study

Aim: The aim was to evaluate the impact of different temporomandibular disorder (TMD) diagnoses on the thickness of the masseter and temporalis muscles. Materials and Methods: Individuals were divided into four groups: (1) myofascial pain; (2) disc displacements; (3) mixed group; and (4) asymptomatic control group. 53 individuals with TMD and 20 individuals without TMD were recruited. Results: No significant differences were found among groups in masseter and temporalis muscles thickness at rest and maximum contraction (p&amp;gt;0.05). However, the masseter muscle thickness at rest and maximum contraction were greater in asymptomatic individuals than in individuals with TMD (p&amp;lt;0.05). Conclusion: Masseter and temporalis muscles thickness are similar in the TMD subgroups and the asymptomatic control group at rest and maximum contraction.

Evaluation of the thickness of masticatory muscles in patients with chronic periodontitis by ultrasonography.

Periodontitis is one of the most common chronic inflammatory diseases. It causes changes in the biting abilities of individuals. However, periodontal treatment has positive effects on masticatory function. The aim of this study is to determine the effect of periodontitis and periodontal treatment on masticatory abilities by measuring masseter and temporal muscle thicknesses with ultrasonography before and after periodontal treatment in chronic periodontitis patients. The patients included in the study were determined by clinical and radiological examination. The thickness of the masseter and temporal muscles of the patients were measured by ultrasonography. Periodontal measurements and treatments of the patients were completed by a single physician. IBM SPSS 20.0 (IBM Corp., Armonk, NY) statistical program was used for statistical analysis. A statistically significant difference was found between the values of periodontal measurements before and after treatment (p<0.05). In the ultrasonography measurements of the thickness of masseter and anterior temporal muscles, a statistically significant increase was observed in both rest and contraction values at all time intervals (p<0.05). Muscle thicknesses of male patients were higher than female patients. Periodontitis negatively affects the masticatory performance of individuals. Chronic periodontitis patients should be referred for periodontal treatment without wasting time.

Comparison of ultrasonography-based masticatory muscle thickness between temporomandibular disorders bruxers and temporomandibular disorders non-bruxers

To compare masticatory muscle thickness in patients with temporomandibular disorders (TMDs) during rest and clenching, and by body position, using ultrasonography. This prospective study included 96 patients with TMD (67 females, 29 males; mean age: 40.41 ± 17.88 years): group 1, comprising 66 patients with TMD without bruxism (TMD_nonbruxer), and group 2, comprising 30 patients with concurrent TMD and bruxism (TMD_bruxer). In patients with TMD, bruxism was correlated with the presence of tinnitus, muscle stiffness, sleep problems, psychological stress, and restricted mouth opening. The masseter muscle significantly thickened during clenching (11.16 ± 3.03 mm vs 14.04 ± 3.47 mm, p < 0.001), whereas the temporalis muscle showed no significant increase in thickness from resting to clenching in an upright position (7.91 ± 1.98 vs 8.39 ± 2.08, p = 0.103). Similarly, during clenching in the supine position, the masseter muscle was significantly thicker compared with rest (11.24 ± 2.42 vs 13.49 ± 3.09, p < 0.001), but no significant difference was observed in temporal muscle thickness (8.21 ± 2.16 vs 8.43 ± 1.94, p = 0.464). In comparison between two groups, the average thickness of the masseter muscle was greater among TMD_bruxers than among TMD_nonbruxers in both the upright and supine positions (all p < 0.05). In the generalized lineal model, female sex (B = − 1.018, 95% confidence interval [CI] − 1.855 to − 0.181, p = 0.017) and bruxism (B = 0.868, 95% CI 0.567 to 1.169, p = 0.048) significantly predicted changes in masseter muscle thickness. Female sex (B = − 0.201, 95% CI − 0.299 to − 0.103, p = 0.011), increased age (B = − 0.003, 95% CI − 0.005 to 0.000, p = 0.038), and muscle stiffness (B = − 1.373, 95% CI − 2.369 to − 0.376, p = 0.007) were linked to decreased temporal muscle thickness. Comparing TMD nonbruxer and bruxer muscle thicknesses in upright and supine positions revealed significant increased thickness in the masseter muscle during clenching but not in the temporalis muscle. Masseter muscle thickness varied significantly by sex, body position, and resting/clenching, notably influenced by bruxism. These findings emphasize the relevance of these factors in clinical examinations of patients with TMD.

Efficacy and Safety of PrabotulinumtoxinA in Subjects With Benign Masseteric Hypertrophy: A Double-Blind, Randomized, Placebo-Controlled, Multicenter, Phase 3 Trial and Open-Label Extension Study.

Despite the widespread use of botulinum toxin (BTX) injection for the treatment of masseter muscle hypertrophy (MMH), there is no standard treatment option. We report the efficacy and safety for BTX in MMH over a period of 48 weeks. In double-blinded, placebo-controlled phase 3 trials, 180 patients (randomized 1:1) received treatment with placebo (normal saline) or prabotulinumtoxinA (48 units). Masseter muscle thickness (at maximal clenching and resting positions), 3D imaging analysis, and masseter muscle hypertrophy scale grades were analyzed at each time point. After the 24-week CORE study, all patients who met the same criteria of the CORE study at week 24 ( n = 114) received only prabotulinumtoxinA, regardless of previous treatment, for an additional 24 weeks (48 weeks in total) for the open-label extension study. The largest differences in mean and percent changes from baseline in masseter muscle thickness were observed at 12 weeks, and there were significant differences between the 2 groups at all time points (all p < .001). The effect was independent of the number of injections. No serious adverse event was observed. PrabotulinumtoxinA could effectively ameliorate MMH without major complications.

Masseter Muscle Thickness in Relation to Facial Form in Angle’s Normal Occlusion and Malocclusions: An Observational Study

ABSTRACT Background: Various clinical studies performed in adults have shown the relationship between craniofacial morphology and masticatory muscle function. However, the growth of the masticatory muscle has not received such attention, when compared with the volume of studies on the skeletal growth of face. With this background and considering the widespread use of ultrasonography (USG), the following study was undertaken to provide some insights into the relationship between muscle and bone and facial morphology. Methods: This was a prospective, observational study conducted over a period of three years from 2012 to 2015 to assess the correlation between the thickness of the masseter muscle in Angle’s normal occlusion and the various malocclusions of the dental arch as well as the facial form. Patients with a full complement set of teeth, normal tooth morphology, Angle’s normal occlusion, Angle’s class I-III malocclusion, those with a history of third molar extraction, and impaction were included in the study. Those with a history of any prior orthodontic treatment, restorations, or any missing teeth (except the third molar) were exempted from the study. The greater thickness of masseter muscle in relaxed and clenched state was recorded on USG. Facial morphology was determined with the aid of facial photographs. Results: The study was conducted on 140 patients. The class I normal occlusion group had the thickest masseter muscle, while the class III malocclusion group had the thinnest masseter muscle. Facial parameters showed highly significant gender-wise differences in class I normal occlusion, class I malocclusion, and class II division II malocclusion. There was a significant negative co-relation between the thickness of masseter muscle and facial forms in all the categories of Angle’s classification as indicated by a negative regression coefficient B (P &lt; 0.05) Conclusion: The masseter muscle thickness correlated directly with male gender and normal occlusion, and inversely with the degree of malocclusion and facial form.

Quantitative and qualitative evaluation of the masseter muscle by ultrasonography and correlation with whole body health status.

[Purpose] Ultrasonography can be used to non-invasively analyze any cross-section of the human body and to measure tissue elasticity, thickness, and brightness. This study was performed to examine the quantitative and qualitative changes in the masseter muscle at rest and at maximal occlusion, and to evaluate the relationship between these changes and the general health of the individual. [Participants and Methods] The study cohort comprised 30 healthy adults. Correlations between basic participant information (sex, age, height, body weight, body mass index, body fat, maximum bite force, handgrip strength, and tongue pressure) and masseter muscle ultrasonographic data were examined. [Results] Masseter muscle thickness was significantly greater in males than in females. Body weight and body mass index correlated positively with masseter muscle thickness. Body mass index and body fat percentage correlated positively with masseter muscle brightness. Tongue pressure correlated positively with handgrip strength. [Conclusion] Our analyses of muscle thickness and brightness suggest that ultrasonography may be useful in evaluating masseter muscle quantity and quality, and that the condition of the masseter muscle may correlate with the overall health status of the individual.

Dextrose neuroprolotherapy and occlusal splint treatment outcomes in occlusal trauma: Evaluation through ultrasound imaging.

Occlusal trauma has become a common phenomenon among individuals today. Its primary source is bruxism, which involves unusual activities such as clenching and grinding during the day or sleep. The hypothesis is that with 5% dextrose neuroprolotherapy, both the trigger points and affected nerves will be healed, and the muscle will be relieved by eliminating the pain. This study aimed to compare the short-term ultrasonographic results of patients treated with occlusal splint and 5% dextrose neuroprolotherapy for bruxism. Patients were divided into two groups: the dextrose neuroprolotherapy group and the occlusal splint group. In the first group, patients were administered 5% dextrose three times at one-week intervals using the dextrose neuroprolotherapy method. Impressions for both jaws were made using a high-viscosity irreversible hydrocolloid impression material in the second group. An occlusal splint was tailored to fit the upper jaw. Patients were assessed for masseter muscle thickness and strain ratio using ultrasonography before and 3 months after the treatment. No statistically significant differences were found between the two groups for all measures. Statistically significant differences were observed in the strain ratio of the left musculus massetericus in the resting position and the thickness of the left musculus massetericus in the contracted position exclusively in the neuroprolotherapy group (p=0.001, p=0.011, respectively). Differences in the strain ratio of both sides of the contracted musculus massetericus were demonstrated in both groups (neuroprolotherapy group: right side p<0.001, left side p=0.007, splint group: right side p=0.005, left side p=0.012). This study demonstrates that 5% dextrose neuroprolotherapy is an effective treatment comparable to an occlusal splint. Objectively visualizing changes in the masseter muscle through ultrasound provides clear results in the context of occlusal trauma and bruxism.

Impact of different cephalometric skeletal configurations on anatomic midface parameters in adults

ObjectivesSkull morphology and growth patterns are essential for orthodontic treatment, impacting clinical decision making. We aimed to determine the association of different cephalometric skeletal configurations on midface parameters as measured in 3D CT datasets.Materials and methodsAfter sample size calculation, a total of 240 fully dentulous patients between 20 and 79 years of age (mean age: 42 ± 15), who had received a CT of the skull within the scope of trauma diagnosis or intracranial bleeding, were retrospectively selected. On the basis of cephalometric analysis, using MPR reconstructions, patients were subdivided into three different vertical skull configurations (brachyfacial, mesofacial, dolichofacial) and the respective skeletal Class I, II, and III relationships. Anatomic parameters were measured using a three-dimensional post-processing console: the thickness of the maxillary and palatine bones as well as the alveolar crest, maxillary body and sutural length, width and height of the hard palate, maxillary facial wall thickness, and masseter muscle thickness and length.ResultsIndividuals with brachyfacial configurations had a significantly increased palatal and alveolar ridge thicknesses compared to those with dolichofacial- or mesofacial configurations. Brachyfacial configurations presented a significantly increased length and thickness of the masseter muscle (4.599 cm; 1.526 cm) than mesofacial (4.431 cm; 1.466 cm) and dolichofacial configurations (4.405 cm; 1.397 cm) (p < 0.001). Individuals with a skeletal Class III had a significantly shorter palatal length (5.313 cm) than those with Class I (5.406 cm) and Class II (5.404 cm) (p < 0.01). Sutural length was also significantly shorter in Class III (p < 0.05).ConclusionsSkeletal configurations have an impact on parameters of the bony skull. Also, measurable adaptations of the muscular phenotype could result.Clinical relevanceThe association between viscerocranial morphology and midface anatomy might be beneficial for tailoring orthodontic appliances to individual anatomy and planning cortically anchored orthodontic appliances.

Determination of masseter and temporal muscle thickness by ultrasound and muscle hardness by shear wave elastography in healthy adults as reference values.

The purpose of this study is to prospectively investigate the reference values of masseter and temporal muscle thicknesses by ultrasonography and muscle hardness values by shear wave elastography in healthy adults. The sample of the study consisted of a total of 160 healthy individuals aged between 18 and 59, including 80 women and 80 men. By examining the right and left sides of each participant, thickness and hardness values were obtained for 320 masseter muscles and 320 temporal muscles in total. The mean masseter muscle thickness was found to be 1.09 cm at rest and 1.40 cm in contraction. The mean temporal muscle thickness was found to be 0.88 cm at rest and 0.98 cm in contraction. The thickness values of the masseter and temporal muscles were significantly greater in the male participants than in the female participants (P < .001). While there were significant differences between the right and left masseter muscle thickness values at rest and in contraction, the values of the temporal muscles did not show a significant difference between the sides. While the resting hardness (rSWE) of the masseter muscle was transversally 6.91 kPa and longitudinally 8.49 kPa, these values in contraction (cSWE) were found, respectively, 31.40 and 35.65 kPa. The median temporal muscle hardness values were 8.84 kPa at rest and 20.43 kPa in contraction. Masseter and temporal muscle hardness values at rest and in contraction were significantly higher among the male participants compared to the female participants (P < .001). In this study, reference values for the thickness and hardness of the masseter and temporal muscles are reported. Knowing these values will make it easier to assess pain in the masseter and temporal muscles and determine the diagnosis and prognosis of masticatory muscle pathologies by allowing the morphological and functional assessments of these muscles, and it will identify ranges for reference parameters.

Influence of Digit Sucking Habit on Masseter Muscle Thickness and Upper Airway Dimensions in Nigerian Children

Background: Digit sucking habit (DSH) generates functional forces that can influence craniofacial morphology. Although the dental effects have been widely reported, its influence on the masseter muscle thickness (MMT) and upper airway (UA) dimensions is not well known.&#x0D; &#x0D; Methods: Thirty (30) children selected from the orthodontic clinic (OAUTHC), with a DSH were matched with a group of 30 children without a DSH. Each group comprised of 16 males and 14 females. Ultrasonographic evaluation of the masseter muscle (MM) was performed to measure the left and right MMT in the relaxed and contracted states. Lateral cephalometric radiographs were obtained and 6 UA variables were measured on the x-ray. Data was analysed using SPSS version 20.0. Statistical significance was set at p&lt;0.05.&#x0D; Inferential statistics was done using independent sample t test to compare means.&#x0D; Results: Participants in the DS group had a mean age of 7.7 ± 2.2 years, whereas those in the non-DS group had a mean age of 8.1 ± 2.1 years. The MM was generally thicker among the DS group, both in the contracted and relaxed states when compared with the non-DS group, but these differences were not statistically significant (p&gt;0.05). The mean measurement of the width of the nasopharynx (P1) was significantly decreased among the DS group when compared with the non-DS group (p&lt;0.05). There was no statistically significant difference in the mean values for the width of the oropharynx (P2), hypopharynx (P3), soft palate length (PNS-U1) and thickness (MPT) and the posterior bony boundary of the nasopharynx (PNS-Ba) between both groups. (p&gt;0.05).&#x0D; Conclusion: Digit sucking habit caused a statistically significant narrowing of the width of the nasopharynx (p&lt;0.05). The MMT did not differ significantly between the DS and non-DS groups both in the relaxed and contracted states.