Medial Pterygoid Research Articles

Recurring myositis ossificans traumatica of temporal muscle: A case report

Introduction. Myositis ossificans traumatica (MOT) refers to a benign, localized ectopic bone formation within skeletal muscle bundles related to a traumatic injury. MOT rarely affects masticatory muscles, and it represents a major diagnostic and therapeutic problem for clinicians. Currently, the treatment of choice is complete excision of the calcified mass after bone maturation and resection of the affected bone. Case report. A 47-year-old male presented with a month-long severe restriction of mouth opening that was followed by extraction of the right lower third molar tooth under local anesthesia. A computed tomography (CT) scan revealed ectopic bone formation in the right temporal muscle extending to the right coronoid process. Surgical excision of the calcified mass was performed. Six years after the surgery, the patient reported the same symptoms. The CT scan revealed a calcified mass of the right temporal muscle extending to the medial pterygoid muscle. The patient was reoperated, and sent for the postoperative physical treatment. Conclusion. MOT represents a major diagnostic and therapeutic challenge for surgeons due to unclear etiology and frequent recurrences after surgical treatment. Further research is needed to clarify the mechanisms of ossification in MOT in order to develop conservative treatment approaches.

Counter-Clockwise Rotation of Maxillomandibular Complex and Customized Joint Reconstruction as a Single Stage Management for Facial Deformity in Temporomandibular Joint Ankylosis: A 2 Year Follow-Up

Study Design: A case report with 2 year follow up. Objective: The aim of this paper is to present a case of bilateral TMJ ankylosis with coexisting dentofacial deformity and occlusal cant, and 2 years follow-up evaluation for changes and relapse in the facial skeletal and airway. Methods: The patient was planned preoperatively by computer simulation for bilateral interposition arthroplasty and surgical jigs, coronoidectomy, detachment of masseter and medial pterygoid muscles from ramus, LeFort 1 osteotomy, temporary maxillomandibular fixation, counter-clockwise rotation of the maxillomandibular complex, maxillary fixation and iliac crest graft, reconstruction of bilateral TMJ with custom-made total joint prosthesis, dermal fat interposition in the joint, reattachment of muscles, maxillomandibular fixation, and active physiotherapy. Results: Average ramal length improved by 28.35 mm (81%) in the immediate postoperative and 25.6 mm (73.45%) at 2 years, showing 2.75 mm (4.4%) vertical bone resorption at the angle region. Point A advanced by 1.3 mm, but showed 4.5% horizontal relapse; Point B advanced by 10.2 mm, but showed 9.5% relapse at 2 years. Pogonion advanced by 26.3 mm (70%) but presented 7 mm (10.9%) horizontal relapse; and menton by 28.6 mm (89%) with 5.4 mm (8.9%) relapse at 2 years. The mean mandibular plane angle decreased by 33.5° (42%) after surgery and by 32° (40%) at 2 years. Pharyngeal airway increased by 49% after surgery and by 75.6% at 2 years follow-up. Conclusion: This computer simulated approach for the management of bilateral TMJ ankylosis with facial deformity and occlusal cant improves aesthetics, function and airway in a single surgery, thereby reducing the management cost and time, and deliver precise results.

Malignant melanoma of the nasal mucosa

Nose's Paranasal sinus & malignant melanoma are rarely seen, bold tumor with a prevalence rates of 0.68 percent across every malignant tumor. The neuroectodermal cells which are termed as Melanomas are found in skin's base layer, iris’s vascular intraocular coat, skin adnexa, & infrequently into outer covering of mucous. Blockage feeling of nose & bleeding from the nose are the symptoms which are most commonly reported, however patient may have symptoms that are nonspecific, leading to a delay in diagnosis which results in appropriate prediction of treatment's outcome. This study defines a 70 years female with the history of nose blockage feeling. Physicians suggest performing Nose’s CT scan, in which they came to know that large polypoidal portion in right nostril, extending to the nasopharynx, and eroded part of the sinus wall, septum and right medial pterygoid plate. Immunochemical study done revealed positive results for S100, vimentin, & HMB-45, which made the outcome suitable for tumor. An individual suffering from this will have no recurrence.

Functional properties of single motor units in the human medial pterygoid muscle: Thresholds.

Little is known regarding the functional properties of single motor units (SMUs) in the medial pterygoid muscle (MPt) during jaw movements. The aims are (a) to report the thresholds of onset of MPt SMUs during 4 goal-directed jaw movement tasks, and (b) to determine whether the threshold of onset of SMU activation varies with the velocity of jaw movement and the location within the muscle. Intra-muscular electrodes were inserted in the right MPt of 18 participants performing ipsilateral (right), contralateral, protrusive and opening-closing jaw movements recorded at 2 velocities. Task phases were as follows: BEFORE, OUT, HOLDING, RETURN and AFTER. SMU onset thresholds were determined from the displacement (mm) of the lower mid-incisor point. Electrode location within 4 arbitrary muscle divisions was determined with computer tomography. Statistical tests: Spearman's correlations, Kruskal-Wallis tests; significance accepted at P<.05. A significant inverse relation occurred between velocity and threshold for the RETURN of the ipsilateral movement (n=62 SMU thresholds), while a significant positive relation occurred for the OUT of the contralateral movement (n=208); there were no significant associations for the protrusive (n=131) and opening-closing (n=58) tasks. Significant threshold differences occurred across the 4 muscle divisions only during the OUT of the contralateral and protrusive movements. Some evidence was provided for gender differences in MPt SMU properties. The absence of a significant inverse relation between velocity and SMU threshold for most recorded movements suggests the MPt acts as a stabilizer of the jaw in horizontal and opening-closing jaw movements.

Correlation between mandibular morphology and masticatory muscle thickness in normal occlusion and mandibular prognathism.

ObjectivesThe aim of this study was to evaluate the relationship between masticatory muscle thickness and mandibular morphology in young Korean adults with normal occlusion and mandibular prognathism.Patients and MethodsMultidetector computed tomography (MDCT) was used to measure the masticatory muscle thickness on the right side in 100 Korean young adults (50 normal occlusion group, 50 mandibular prognathism group). Cephalometric analysis was done to measure mandibular morphology. Pearson correlation analysis was done to investigate the relationship between the masticatory muscle thickness and mandibular morphometry.ResultsThe four masticatory muscles showed positive correlation with intergonial width in all subjects. All muscles, except temporalis, positively correlated with height of the ramus and mandibular length. Positive correlation was also observed in all muscles, except medial pterygoid, with thickness of the ramus. In the normal occlusion group, all four masticatory muscles showed positive correlation with intergonial width and ramus thickness. Positive correlation was also observed in all muscles (except lateral pterygoid) with mandibular length. Masseter and lateral pterygoid positively correlated with height of the ramus. In the mandibular prognathism group, all masticatory muscles, except lateral pterygoid, showed positive correlation with intergonial width. The masseter muscle showed negative correlation with ANB.ConclusionThe results suggest a positive correlation of the thickness of masticatory muscles with both horizontal and vertical dimensions of the mandible. However, thickness of the masseter was found to decrease in patients with increasing severity of mandibular prognathism.

Trismus: an unusual cause and its implications

AbstractSystemic diseases can manifest in many ways and subtle clues to these processes can often declare themselves in the maxillofacial region. This report highlights one usual and rare presentation of such case. A 64‐year‐old woman, presented to her general practitioner with worsening right‐sided jaw pain and trismus. She was referred to the local maxillofacial services and her mouth opening was measured at 1cm at presentation. An orthopantomogram (OPG) taken was unremarkable. She underwent an MRI of the head and neck that showed a soft tissue mass invading the right lateral and medial pterygoid muscles and plate with involvement of the ramus of the mandible. A staging CT was performed that revealed a mass of the proximal sigmoid colon. A colonoscopy performed with biopsy revealed a poorly differentiated squamous cell carcinoma with extensive metastasis, including the right masticatory space. She was presented at the multi‐disciplinary meeting where it was decided to treat her palliatively and she died 6 weeks after her diagnosis.

BIOMECHANICAL EVALUATION OF RECONSTRUCTED EXTENSIVE MANDIBULAR DEFECTS BY DIFFERENT MODELS USING FINITE ELEMENT METHOD

Rehabilitation of major mandibular defects after tumor resection has become a serious challenge for surgeons. In this research, four various models were designed to repair a critical mandibular lateral defect. Biomechanical behavior of the models was assessed by Finite Element Method. These models are including Fibular-Free Flap (FFF), Customized Prosthesis (CP), Tray Implant without Bone Graft (TI-wo-BG), and Tray Implant with Bone Graft (TI-w-BG). FFF is a subset of microvascular free flap technique in which some segments of patient’s fibula bone are used to restore mandibular defects. CP is a hollow and light prosthesis which is fabricated using Additive Manufacturing technology from Ti alloy powder. TI-wo-BG is similar to a crib which is designed according to the geometry of the patient’s mandible. TI-w-BG, in fact, is a TI-wo-BG which is filled with small cortico-cancellous chips in order to benefit potential profit of bone grafting. The chewing operation and loading on the mandible was simulated considering the three mandibular muscular forces including masseter, medial pterygoid, and temporalis. The result of FEM analysis of TI-wo-BG and TI-w-BG showed that in both models, screw number 6 endured a strain of 5684 and 2852[Formula: see text][Formula: see text]m/m which exceeded pathological and mild overload risk, respectively. This may increase the probability of screw loosening and system failure. The results proved the stability of the FFF and CP models. In addition, it can be concluded that stress and strain on the screw’s interfaces can decrease by improving the plate and increasing the friction at the interface of plate, bone and screw.

Intraosseous neurofibroma of the mandible involving masticator space

Neurofibroma is a benign, heterogenous peripheral nerve sheath tumor arising from the connective tissue of peripheral nerve sheaths, especially the endoneurium. Its intraoral occurrence is uncommon and its occurrence within mandible is extremely rare. A case of solitary intraosseous neurofibroma of the mandible involving masticator space in a 8-year-old male is reported. He was referred from a private local clinic with a chief complaint of limitation in opening of the mouth. Panoramic and cone-beam computed tomographic images showed unilocular radiolucent lesion with scalloped border at the right mandibular ramus, connected posteriorly to the enlarged mandibular foramen and anteriorly to the mandibular canal. T1-weighted magnetic resonance images showed soft tissue mass of isointensity compared with muscles. Contrast-enhanced T1-weighted images showed peripheral enhancement and T2-weighted images showed the heterogeneous hyperintense mass with extension between lateral and medial pterygoid muscles. The tumor was surgically removed under general anesthesia and diagnosed to be neurofibroma at the biopsy.

Morphological changes in temporomandibular joint dysfunction and effectiveness of different treatment methods

Objectives: Temporomandibular joint dysfunction (TMD) results in changes in anatomical structures. The aim of this study was to examine the morphological changes using magnetic resonance imaging (MRI) and evaluate the effectiveness of different treatment methods in patients with TMD. Methods: 34 TMD patients (18–62 years of age) were randomly divided into two treatment groups. Group A (n=18) was subjected to dry needling (DN) and mobilization for 10 sessions, Group B (n=16) was instructed to use occlusal splint with home exercises for one month. The control group included MRIs of 17 healthy adults that were randomly selected from the archives of Radiology Department of Mustafa Kemal University. The length and width of the masseter, lateral and medial pterygoid muscles and the depth of the mandibular fossa were measured and mandibular condyle types were recorded. Range of motion of each temporomandibular joint was evaluated in pre- and post-treatment periods to test the effectiveness of the treatment methods. Results: The size of the masticatory muscles in TMD group was significantly smaller than the control group (p&lt;0.05). The depth of the mandibular fossa was significantly shallower in the TMD group (p&lt;0.05). The most commonly encountered condylar shape was convex in the TMD group (63.6%), but flat (58.8%) in the control group. No statistically significant relationship was observed between condyle type and fossa depth (p&gt;0.05). However, the fossa depth showed a significant correlation with muscle size (p&lt;0.05) and this correlation decreased with dysfunction. Dry needling and mobilization significantly decreased pain and increased mandibular movements (p&lt;0.05); however, there was no significant change for Group B. Conclusion: The anatomical structures associated with the temporomandibular joint seems to be affected in patients with TMD. We suggest that the limited movement of the temporomandibular joint may cause atrophy of the masticatory muscles, affecting the range of motion of the joint. Dry needling and mobilization techniques might be a more effective alternative than occlusal splint in the treatment of TMD.

Technical note: Atlas-based Auto-segmentation of masticatory muscles for head and neck cancer radiotherapy.

PurposeThe study aimed to use quantitative geometric and dosimetric metrics to assess the accuracy of atlas‐based auto‐segmentation of masticatory muscles (MMs) compared to manual drawn contours for head and neck cancer (HNC) radiotherapy (RT).Materials and methodsFifty‐eight patients with HNC treated with RT were analyzed. Paired MMs (masseter, temporalis, and medial and lateral pterygoids) were manually delineated on planning computed tomography (CT) images for all patients. Twenty‐nine patients were used to generate the MM atlas. Using this atlas, automatic segmentation of the MMs was performed for the remaining 29 patients without manual correction. Auto‐segmentation accuracy for MMs was compared using dice similarity coefficients (DSCs), Hausdorff distance (HD), HD95, and variation in the center of mass (∆COM). The dosimetric impact on MMs was calculated (∆dose) using dosimetric parameters (D99%, D95%, D50%, and D1%), and compared with the geometric indices to test correlation.ResultsDSCmean ranges from 0.79 ± 0.04 to 0.85 ± 0.04, HDmean from 0.43 ± 0.08 to 0.82 ± 0.26 cm, HD95mean from 0.32 ± 0.08 to 0.42 ± 0.16 cm, and ∆COMmean from 0.18 ± 0.11 to 0.33 ± 0.23 cm. The mean MM volume difference was < 15%. The correlation coefficient (r) of geometric and dosimetric indices for the four MMs ranges between −0.456 and 0.300.ConclusionsAtlas‐based auto‐segmentation for masticatory muscles provides geometrically accurate contours compared to manual drawn contours. Dose obtained from those auto‐segmented contours is comparable to that from manual drawn contours. Atlas‐based auto‐segmentation strategy for MM in HN radiotherapy is readily availalbe for clinical implementation.

Biomechanical Design Application on the Effect of Different Occlusion Conditions on Dental Implants with Different Positions—A Finite Element Analysis

A dental implant is currently the most commonly used treatment for patients with lost teeth. There is no biomechanical reference available to study the effect of different occlusion conditions on dental implants with different positions. Therefore, the aim of this study was to conduct a biomechanical analysis of the impact of four common occlusion conditions on the different positions of dental implants using the finite element method. We built a finite element model that included the entire mandible and implanted seven dental implant fixtures. We also applied external force to the position of muscles on the mandible of the superficial masseter, deep masseter, medial pterygoid, anterior temporalis, middle temporalis, and posterior temporalis to simulate the four clenching tasks, namely the incisal clench (INC), intercuspal position (ICP), right unilateral molar clench (RMOL), and right group function (RGF). The main indicators measured in this study were the reaction force on the temporomandibular joint (TMJ) and the fixed top end of the abutment in the dental implant system, and the stress on the mandible and dental implant systems. The results of the study showed that under the occlusion conditions of RMOL, the dental implant system (113.99 MPa) and the entire mandible (46.036 MPa) experienced significantly higher stress, and the reaction force on the fixed-top end of the abutment in the dental implant system (261.09 N) were also stronger. Under the occlusion of ICP, there was a greater reaction force (365.8 N) on the temporomandibular joint. In addition, it was found that the reaction force on the posterior region (26.968 N to 261.09 N) was not necessarily greater than that on the anterior region (28.819 N to 70.431 N). This information can help clinicians and dental implant researchers understand the impact of different chewing forces on the dental implant system at different positions after the implantation.

Ostmann's Fat Pad-Does it Really Matter?

To compare the size of Ostmann's fat pad (OFP) between healthy ears and ears with chronic otitis media with cholestatoma (COMwC) using magnetic resonance imaging (MRI). Twenty-six patients with unilateral COMwC underwent mastoidectomy. Pre-operative MRI records were reviewed retrospectively. The healthy ears served as the control group. OFP is represented by the maximum diameter of the high intensity area medial to the tensor veli palatini muscle (TVP); M1. A reference diameter was defined from the medial border of OFP reaching the medial border of the medial pterygoid muscle; M2. Values of M1, M2 and the ratio of M1:M2 was compared between the healthy and pathological ear in each patient. All 26 patients (16 females,10 males) had unilateral cholestatoma. Mean age was 37.6 years (range 19-83). In the healthy (H) ears group, mean M1H was 2.04 ± 0.53 mm, mean M2H was 9.57 ± 2.57 mm.In the pathological (P) ears group; mean M1P was 2.03 ± 0.55 mm, mean M2P was 9.86 ± 2.37 mm. A comparison of M1 and M2 values between the healthy and pathological ear groups was not statistically significant (P = .853 and P = .509, respectively).Mean M1H:M2H ratio in the healthy ears group was 0.22 ± 0.05, mean M1P:M2P ratio in the pathological ear group was 0.21 ± 0.06. A comparison between these ratios found no significant statistical correlation (P = .607). The size of Ostmann's fat pad does not affect the development of chronic otitis media with cholestatoma in adults.

Anatomical relationship of pterygoid process pneumatization and vidian canal

IntroductionThe vidian canal acts as landmark for the identification of the petrous carotid artery, especially during extended endoscopic endonasal approaches in cranial base surgeries. In order to localize the canal and to understand the relationship of pneumatization of pterygoid process to the type of vidian canal, this study was designed. ObjectivesThe objective was to describe the anatomical relationship of pneumatization of the pterygoid process with types of vidian canal. The length of vidian canal, relationship to medial plate of pterygoid process and relationship to the petrous part of internal carotid artery were evaluated. MethodsHead computer tomography scans of 52 individuals for suspected paranasal pathology were studied. The degree of sphenoid sinus pneumatization, pterygoid process pneumatization and types of vidian canal (type 1, 2 and 3) were noted. The length of vidian canal, distance from the plane of medial pterygoid plate and relation of vidian canal to the junction of petrous and Gasserian (ascending) part of internal carotid artery was noted. Results46 (92%) sphenoid sinuses were of the sellar variety. Out of 104 sides that were studied, 57 sides demonstrated a pneumatised pterygoid process and 47 were not pneumatised. In 49 sides (47.1%) the vidian canal was on the same plane as that of the medial pterygoid plate in the coronal section. The vidian canal partially protruded into the sphenoid sinus (type 2) was the most common type (50.9%), found both on right and left sides. There is a statistically significant association between the pterygoid process pneumatization and occurrence of type 2 and type 3 vidian canal configuration. The average length of the vidian canal was 16.16 ± 1.8 mm. In 96 sides, the anterior end of vidian canal was inferolateral to petrous part of internal carotid artery in the coronal plane. ConclusionPneumatization of the pterygoid process indicates either type 2 or type 3 vidian canal configuration.

Tomographic assessment of palatal suture opening pattern and pterygopalatine suture disarticulation in the axial plane after midfacial skeletal expansion

ObjectiveThe purpose of this study was to assess the palatal suture opening and the pterygopalatine suture disarticulation pattern in the tomographic axial plane after treatment with midfacial skeletal expander (MSE).Materials and methodsPre- and post-expansion CBCT records of 50 subjects (20 males, 30 females, mean age 18 ± 3 years) who were treated with MSE (Biomaterials Korea, Seoul, Korea) appliance were superimposed and compared using OnDemand software. Reference planes were identified and the angulation of the midpalatal suture opening after expansion was calculated as well as the frequency of the pterygopalatine suture split.ResultsAfter MSE treatment, the mean palatal suture opening angle (SOA) was 0.57°. (− 0.8° to 1.3°). There was no significant difference between males and females in terms of the palatal suture opening pattern (P > 0.05). Only 3 out of 50 (6%) subjects presented SOA above 1 degree. Also, 3 out of 50 (6%) patients presented a negative SOA value. With regard to the pterygopalatine suture split, 84 sutures out of 100 (84%) presented openings between the medial and lateral pterygoid plates on both right and left sides. Partial split was detected with 8 patients (5 females, 3 males). Five patients had split only in the medial pterygoid plates of both pterygomaxillary sutures, and 3 patients exhibited disarticulation on the right side only. No significant differences were found in the frequency of suture opening between males and females (P = 1.000).ConclusionsMSE appliance performed almost parallel expansion in the axial view. Remarkably, this study shows that pterygopalatine suture can be split by MSE appliance without the surgical intervention; the disarticulation of pterygopalatine suture was visible in most of the patients.

Deep learning vs. atlas-based models for fast auto-segmentation of the masticatory muscles on head and neck CT images

BackgroundImpaired function of masticatory muscles will lead to trismus. Routine delineation of these muscles during planning may improve dose tracking and facilitate dose reduction resulting in decreased radiation-related trismus. This study aimed to compare a deep learning model with a commercial atlas-based model for fast auto-segmentation of the masticatory muscles on head and neck computed tomography (CT) images.Material and methodsPaired masseter (M), temporalis (T), medial and lateral pterygoid (MP, LP) muscles were manually segmented on 56 CT images. CT images were randomly divided into training (n = 27) and validation (n = 29) cohorts. Two methods were used for automatic delineation of masticatory muscles (MMs): Deep learning auto-segmentation (DLAS) and atlas-based auto-segmentation (ABAS). The automatic algorithms were evaluated using Dice similarity coefficient (DSC), recall, precision, Hausdorff distance (HD), HD95, and mean surface distance (MSD). A consolidated score was calculated by normalizing the metrics against interobserver variability and averaging over all patients. Differences in dose (∆Dose) to MMs for DLAS and ABAS segmentations were assessed. A paired t-test was used to compare the geometric and dosimetric difference between DLAS and ABAS methods.ResultsDLAS outperformed ABAS in delineating all MMs (p < 0.05). The DLAS mean DSC for M, T, MP, and LP ranged from 0.83 ± 0.03 to 0.89 ± 0.02, the ABAS mean DSC ranged from 0.79 ± 0.05 to 0.85 ± 0.04. The mean value for recall, HD, HD95, MSD also improved with DLAS for auto-segmentation. Interobserver variation revealed the highest variability in DSC and MSD for both T and MP, and the highest scores were achieved for T by both automatic algorithms. With few exceptions, the mean ∆D98%, ∆D95%, ∆D50%, and ∆D2% for all structures were below 10% for DLAS and ABAS and had no detectable statistical difference (P > 0.05). DLAS based contours had dose endpoints more closely matched with that of the manually segmented when compared with ABAS.ConclusionsDLAS auto-segmentation of masticatory muscles for the head and neck radiotherapy had improved segmentation accuracy compared with ABAS with no qualitative difference in dosimetric endpoints compared to manually segmented contours.

Mandibular ramus fracture: A rare fracture of maxillofacial region

Mandibular ramus fracture: A rare fracture of maxillofacial region - JOOO- Print ISSN No: - 2395-6186 Online ISSN No:- 2395-6194 Article DOI No:- 10.18231/j.jooo.2020.017, Journal of Oral Medicine, Oral Surgery, Oral Pathology and Oral Radiology-J Oral Med Oral Surg Oral Pathol Oral Radiol

Practical Guide for Identification of Internal Carotid Artery During Endoscopic Nasopharyngectomy.

View Supplementary Video 1 Laryngoscope, 2020

Evaluation of the Pterygomaxillary Separation Pattern in Le Fort I Osteotomy Using Different Cutting Instruments

Pterygomaxillary separation (PMS) is considered the main reason for serious complications associated with Le Fort I osteotomy. The aim of this study was to evaluate whether a piezo surgery, ultrasonic bone scalpel, or conventional bur used in Le Fort I osteotomy has an influence on PMS patterns. Using a retrospective cohort study design, we enrolled a sample composed of patients who underwent orthognathic surgery. The primary predictor variables were the cutting instruments (ultrasonic bone scalpel, piezo surgery, and Lindeman bur) used to perform Le Fort I osteotomy. Other variables were demographic and anatomic parameters. The outcome variable was the type of PMS pattern, classified as follows: type 1, PMS at the pterygomaxillary junction (ideal PMS); type 2, PMS at the greater palatine foramen; type 3, PMS from the posterior wall of the maxillary sinus; and type 4, PMS with lateral or medial pterygoid fracture. Anatomic parameters, that is, the thickness and width of the pterygomaxillary junction and distance of the greater palatine foramen, were measured on preoperative cone-beam computed tomography images. The pattern of PMS was evaluated on postoperative cone-beam computed tomography. Data were analyzed using analysis of variance and the Pearson χ2 test. P<.05 was considered statistically significant. This study sample was composed of 96 PMSs in 48 patients. The most common type of PMS was type 1 (58), followed by type 4 (21), type 2 (10), and type 3 (7). A statistically significant relation was found between the cutting instrument and the ideal separation (type 1 PMS) pattern (P=.032), and the highest rate of the ideal separation pattern was seen in the ultrasonic bone scalpel group, at 24 of 32, compared with 22 of 38 in the piezo surgery group and 12 of 26 in the conventional bur group. According to the study, the ultrasonic bone scalpel is safer than other cutting instruments in terms of the ideal separation of the pterygomaxillary junction.

Oral intramuscular myxoma: case report and brief review of the literature

Myxomas are rare benign mesenchymal soft tissue tumors that seldom affect the head and neck area. The present report describes a rare case of intramuscular myxoma of the oral cavity and briefly reviews the literature regarding the occurrence of these lesions in the maxillofacial area. A 59-year-old patient was referred for the development of a slow-growing tumefaction in the right buccal mucosa in the previous 12 months. Magnetic resonance imaging was performed to characterize the lesion's dimensions and its relationship with the surrounding structures, and it revealed intramuscular localization in correspondence with the medial pterygoid muscle. Incisional biopsy was carried out to aid in the final diagnosis. Histology revealed the presence of an intramuscular myxoma, characterized by discontinuous margins and locally infiltrating muscular fibers. A second surgery was performed to totally remove the lesion. Follow-up at 6 months did not show any signs of recurrence. A literature search was performed to retrieve data on the incidence of oral intramuscular myxomas. To the best of our knowledge, this is the first case of intramuscular myxoma of the medial pterygoid muscle reported in the literature. Although rarely encountered, intramuscular myxomas should be considered when performing differential diagnoses of soft tissue masses at the level of the masticatory muscles.

Beneficial effects of benzodiazepine on masticatory muscle dysfunction induced by chronic stress and occlusal instability in an experimental animal study

Psychological stress and occlusal alteration are important etiologic factors for temporomandibular/masticatory muscular disorders. In particular, the exact physiologic mechanism underlying the relation by occlusal alteration and temporomandibular disorders remains unclear. Our purpose was to test the hypothesis that benzodiazepine therapy is able to prevent metabolic and vascular changes in the medial pterygoid muscle of rats under chronic stress after 14 days of unilateral exodontia. Adult Wistar rats were submitted to unpredictable chronic mild stress (10 days) and/or unilateral exodontia and their plasma and medial pterygoid muscles were removed for analysis. A pre-treatment with diazepam was used to verify its effect on stress. The parameters evaluated included anxiety behavior, plasma levels of corticosterone, metabolic activity by succinate dehydrogenase, capillary density by laminin staining and ultrastructural findings by transmission electron microscopy. Occlusal instability induced anxiety-like behavior on elevated plus-maze test and diazepam administration blocked the appearance of this behavior. Unilateral exodontia promoted in the contralateral muscle an increase of oxidative fibers and capillaries and modification of sarcoplasmic reticulum. Chronic stress caused increased glycolytic metabolism, reduced capillary density and morphological changes in mitochondria on both sides. Association of both factors induced a glycolytic pattern in muscle and hemodynamic changes. Pharmacological manipulation with diazepam inhibited the changes in the medial pterygoid muscle after stress. Our results reveal a preventive benzodiazepine treatment for stress and occlusal instability conditions affecting masticatory muscle disorders. In addition, provide insights into the mechanisms by which chronic stress and exodontia might be involved in the pathophysiology of masticatory muscular dysfunctions.