Injury responses of Sprague-Dawley rat jaw muscles to an experimental unilateral anterior crossbite prosthesis.

OBJECTIVE: Dental occlusion are frequently changed in clinic. Molecular responses in jaw muscles to aberrant dental occlusion are changes are attractive, yet remain are obscure. DESIGN: Unilateral anterior crossbite (UAC) prostheses were applied to Sprague-Dawley rats and then ceased after two weeks to detect the reactions of the masseter, a representative jaw elevator, and the lateral pterygoid muscle (LPM), a representative jaw depressor. RESULTS: Two weeks of UAC elicited mild injury of the two muscles. Myogenesis and protective reactions were detected as increases in αB-crystallin expression in the masseter after 3 days and in the LPM after 2 weeks, and increases in desmin expression in both muscles after 2 weeks. A switch in fibre types from IIb to IIx occurred in the LPM but not in the masseter. Inflammatory responses, shown by the infiltration of inflammatory cells and increases in TNF-α mRNA expression, and fibrosis responses, shown by increased mRNA expression of Type I and III collagens, appeared very mild in the two muscles. These responses were partially recovered by the cessation of UAC. During the whole process, no obvious changes were observed in mitochondrial function, as indicated by the levels of proliferator-activated receptor γ coactivator 1α, mitofusin-2 and voltage-dependent anion channel. CONCLUSIONS: UAC causes injury and very limited inflammatory and fibrosis adaption in the masseter and LPM. Both muscles respond with myogenesis and protective activity. The LPM responds also with muscle fibre isoform alternations. These alterations were partially recovered by the cessation of dental stimulation at an early stage.

Prevention and treatment for the rare complications of arthroscopic surgery in the temporomandibular joint.

PURPOSE: To analyze the rare complications of arthroscopic surgeries in the temporomandibular joint (TMJ) and to investigate the preventive and treating methods. PATIENTS AND METHODS: In this study, 2,034 consecutive patients (2,431 joints), diagnosed as TMJ internal derangement, were treated by arthroscopic surgeries when visiting the TMJ clinic at the Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, between May 2001 and September 2009. The clinical complications were analyzed to investigate cause, prevention, and control measures. RESULTS: Of all 2,034 cases, the complications were shown as follows: 5 joint hemorrhages of the lateral pterygoid muscle vascular, injuries of the lateral pterygoid muscle nerve in 5 joints, 3 joints with broken instruments, rejection reaction in 2 joints, and perforation of tympanic membrane in 2 joints. CONCLUSIONS: Arthroscopic surgery was a safe and effective method to treat TMJ internal derangement; its complications were limited and acceptable, but an experienced operator was required for this surgical technique.

Orthodontics-related foreign body causing trismus.

A previously healthy 13-year-old female patient presented with a 7-day history of otalgia, pharyngitis and trismus without fever, dysphagia or dyspnea. Contrast-enhanced computed tomography revealed an orthodontic archwire penetrating the pterygoid musculature. This case highlights the importance of performing a thorough workup in cases involving unusual symptoms.

Post-surgical unilateral temporomandibular joint dislocation treated by open reduction followed by orthodontic treatment.

A case of prolonged unilateral temporomandibular joint (TMJ) dislocation, which was treated by open surgical reduction and post-surgical orthodontic therapy, is presented. A 58-year-old woman presented complaining of facial asymmetry and malocclusion. She had received surgery for a malignant tumour in the right retromolar region 7 years previously. It was considered that contraction of the pterygoid muscle by surgical injury caused anterior meniscal displacement and TMJ dislocation. Since manual manipulation failed, direct open reduction was performed after separation of the lateral pterygoid muscle from the condylar head and removal of the intra-articular scar tissues. Although the condylar head was returned to the glenoid fossa, optimal occlusion was not obtained because of compensatory tooth movement and inclination. Satisfactory occlusion and symmetric facial appearance were brought about by post-surgical orthodontic therapy.

Myositis ossificans traumatica of the medial pterygoid muscle: a case report.

In this report, we present a case of myositis ossificans traumatica (MOT) of the medial pterygoid muscle that had developed after mandibular block anesthesia administered for endodontic treatment of the lower right second molar, demonstrating typical features of this condition. MOT should be considered as a differential diagnosis when there is severe limitation of jaw opening and an associated trauma. Panoramic radiographs and axial and coronal computed tomography (CT) scans can effectively delineate the calcified mass. Other imaging studies that may be helpful include magnetic resonance imaging (MRI), bone scans, and ultrasound. As shown in our case, calcified masses were found in the right mandibular angle, which severely limited jaw opening. Some earlier reported cases of MOT were treated by extraoral surgical approaches with complete removal of the evolving muscle. The aim of this case report is to present only the diagnostic imaging aspects of myositis ossificans traumatica.

Bursitis of the hamular process. Part II: Diagnosis, treatment and report of three case studies.

In the first part of this series of two papers, the bursa of the tendon of the tensor veli palatini muscle was demonstrated and described histologically. In Part II, the symptoms and the process of diagnosis of bursitis of the hamular process is presented. Additionally, recommended treatment options will be discussed. The article presents three case reports.

Surgical treatment of the fractured and dislocated condylar process of the mandible.

Most fractures of the mandible can be managed conservatively. This report is a retrospective evaluation of the clinical and radiological results in 17 patients with 21 dislocated fractures submitted to open reduction and fixation, employing steel wires and maxillomandibular fixation. Follow-up ranged from 7 to 55 months, (mean 29.5). Functional assessment showed good opening movements (mean 41.9 mm). There were no cases of ankylosis, pain, or paralysis of the facial nerve. Radiological assessment was normal when the lateral pterygoid muscle was maintained adherent to the fractured proximal segment. Radiological signs of bone resorption occurred when the fractured segment was detached from the lateral pterygoid muscle. In our opinion, dislocated condylar process fractures can be managed surgically and with steel wire ligatures and maxillomandibular fixation. Whenever possible, the lateral pterygoid muscle should be inserted into the fractured proximal segment, i.e. as an osteomuscular flap.

Barbed needle and inexplicable paresthesias and trismus after dental regional anesthesia.

The tips of 100 needles that had been used clinically for the administration of mandibular block anesthesia (50 by students and 50 by staff) were examined individually under a dissecting microscope. Sixty percent of these needles were found to be barbed. With the use of an animal laboratory simulation, it has been shown that the tips of standard needles as used in general dental practice will barb if allowed to touch bone (medial aspect of the mandibular ramus) during the administration of a mandibular block for dentistry using the direct approach and that a relationship exists between the pattern of this barbing, the disposition of the bevel of the needle at the time of its insertion, and the likelihood of lingual or inferior dental nerve involvement on withdrawal of the barbed needle. Simple precautions are advanced for reducing the possibility of nerve or other tissue damage from this source.

Asymptomatic myositis ossificans of the medial pterygoid muscles: a case report.

Traumatic myositis ossificans, also known as myositis ossificans circumscripta or fibrodysplasia ossificans circumscripta, is a form of dystrophic calcification leading to heterotopic ossification of intramuscular connective tissue. This is usually due to a single severe injury or repeated minor injuries to muscle, although cases without a history of injury have been reported. Heterotopic ossification is rare in the orofacial region, especially in the medial pterygoid muscles. A case of medial pterygoid myositis ossificans with unique computed tomography findings is described.