Intramuscular Injection of Botulinum Toxin as an Adjunct to Total Joint Replacement in Temporomandibular Joint Ankylosis: Preliminary Reports

Botulinum toxin A in dentistry and orofacial surgery: an evidence-based review - part 1: therapeutic applications

Objective An evidence-based review on the safety and efficacy of botulinum toxin type-A (BoNTA) in orofacial conditions, focusing on the therapeutic applications and role of BoNTA as an adjuvant treatment.Data source and selection Data was collected using PubMed (Medline), Cochrane Library of Systematic Reviews and Cochrane Central Register of Controlled Trials electronic databases. Having satisfied the search parameters, 32 studies for therapeutic applications and 26 for BoNTA as an adjunctive treatment were included. The quality of relevant studies was assessed using the Best Evidence Topics (BETs) Critical Appraisal Tool.Data extraction The highest level of evidence (LOE) behind BoNTA safety and efficacy was for wound healing and scar management in the orofacial surgery context, where BoNTA was presented as an adjunctive modality. Level-I evidence was controversial for temporomandibular disorders and bruxism. However, it showed promising results for painful temporomandibular disorders of myogenic origin refractory to conservative therapies, and to decrease muscle contraction intensity in sleeping bruxism. There was only one level-II study for persistent recurrent aphthous stomatitis. Data showed limited level-III evidence for orofacial pain conditions (temporomandibular joint recurrent dislocation and pain, burning mouth syndrome or atypical odontalgia), oral cancer complications, or as an adjuvant to maxillofacial and orthognathic surgeries. Benefits of BoNTA in prosthodontics had weak level-IV evidence. No evidence was found among the periodontology field.Conclusion There is growing evidence to support the safety and efficacy of BoNTA in the investigated orofacial pathological conditions, with high levels of satisfaction from the patient and clinician perspective. However, there are some inconsistencies and limited high-quality evidence available. Well-designed controlled clinical trials are necessary to evaluate long-term safety, efficacy and cost-effectiveness before BoNTA is widely adopted with irrefutable evidence-based clinical guidelines.

Effect of botulinum toxin-A on pain and mouth opening following surgical intervention in oral submucous fibrosis - A controlled clinical trial

The purpose of this trial was to study the effect on pain and mouth opening of intramuscular injection of botulinum toxin-A into masticatory muscles following surgical intervention in oral submucous fibrosis (OSMF) cases. Injections of either botulinum toxin A (BTX-A) (study group) or normal saline (control group) were given 2 weeks prior to surgical intervention in OSMF patients, into the bilateral masseter and temporalis muscles. All patients were evaluated for pain and ease of active physiotherapy at 1 week and 1, 3, and 6 months after surgery using a numerical rating scale and appropriate questionnaires, with comparisons made between the study and control group patients. Electromyographic studies of the masticator muscles were also carried out in all patients before injection, and at 1 month and 6 months after injection. 20 OSMF patients were equally divided into study and control groups (n = 10 each). At 1, 3, and 6 months after surgery, the study group patients showed significantly greater decreases in pain (p-values of 0.007, 0.001, and 0.005, respectively) and greater ease in physiotherapy compared with the control group. EMG recordings of masticator muscles showed a transient drop in microvolt value in the study group 1 month after injection, unlike the control group recordings. It was concluded that preoperative BTX-A injection was a good addition to surgical therapy in the patient group.

Comparative evaluation of thickness of jaw-closing muscles in patients with long-standing bilateral temporomandibular joint ankylosis: a retrospective case-controlled study

OBJECTIVES

The aim of the study was to compare the thickness and cross-sectional area (CSA) of masseter and medial pterygoid muscles in young patients with long-standing bilateral temporomandibular joint ankylosis (bTMJA) in relation to controls.

METHODS

Axial sections of computed tomography scans of patients with bTMJA from two tertiary care university hospitals were reviewed from 1995 to 2010 and compared to age- and sex-matched controls. The outlines of masseter and medial pterygoid muscles corresponding to a predefined reference plane were traced onto acetate paper. The thickness and CSA of the muscles were calculated using an image-analyzing software and calibrated according to the scale provided in the CT scan slides.

RESULTS

Out of a total of 167 cases of temporomandibular joint ankylosis (TMJA), 15 fulfilled the inclusion criteria. The mean thickness and CSA of masseter and medial pterygoid muscles in cases of bTMJA were 19.4 mm (SD 2.3), 734.9 mm(2) (SD 156.7), 11.53 mm (SD 1.35), and 267.4 mm(2) (SD 65.35), respectively. For the control group, respective values were 10.5 mm (SD 1.8), 430.1 mm(2) (SD 66.8), 9.2 mm (SD 1.2), and 254.6 mm(2) (SD 45.7). There was a statistically significant increased thickness and CSA of the muscles in cases of bTMJA as compared to control as evaluated by Mann-Whitney U test.

CONCLUSIONS

The results show that thickness and CSA of masseter and medial pterygoid muscles in patients with bTMJA were larger as compared to controls. This may suggest that, muscular hyperactivity, may be a cofactor in the pathogenesis of TMJA.

CLINICAL SIGNIFICANCE

Although temporomandibular joint ankylosis is one of the most restrictive musculoskeletal disorder in the maxillofacial region, there is little information on the form and function of jaw muscles in this condition. This study evaluates thickness and cross-sectional areas of jaw elevator muscles and indicates that muscle hyperactivity might be associated with ankylosis, thereby providing a probable hypothesis on the etiopathogenesis of this condition.