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.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Pharmacologic management of trigeminal nerve injury after endodontic treatment: A retrospective analysis.

BACKGROUND: Trigeminal nerve injury following endodontic treatment, leading to unpleasant sensations or partial sensory loss in the face or oral mucosa, is uncommon but significant when it occurs. OBJECTIVE: This study analysed the pharmacological management of trigeminal nerve injuries (TNI) in a university-based hospital. METHODS: We conducted a retrospective analysis of 47 patients who visited the Department of Orofacial Pain and Oral Medicine at Yonsei University Dental Hospital, Seoul, Korea, after TNI following endodontic procedures in primary clinics. Both objective tests and subjective evaluations, assessed the extent and duration of sensory injury during the initial visit. The patient's initial symptoms, presumed cause of TNI, referral delay (time interval between TNI and the first visit to our clinic), and medications were analysed to determine whether these factors affected the outcomes. RESULTS: Most patients with TNI experienced dysesthesia with hypoesthesia (70.2%). The mandibular molars were predominantly affected (72.3%), with the inferior alveolar nerve (IAN), lingual nerve (LN), both IAN and LN, and maxillary nerve compromised in 83.0, 12.8, 2.1, and 2.1% of cases, respectively. Causes of TNI included local anaesthesia (29.8%), overfilling/over-instrumentation (25.5%), endodontic surgery (17.0%), and unknown factors (27.7%). A shorter referral delay was associated with better outcomes, with an average delay of 8.6 weeks for symptom improvement compared with 44.1 weeks for no change. The medication regimens included steroids, NSAIDs, topical lidocaine, vitamin B complex, Adenosine Triphosphate (ATP), antiepileptics, antidepressants, and opioids administered alone or in combination, with a mean duration of 20.7 weeks. 53.2% of the patients reported improvement in their symptoms, 27.7% experienced no significant change, and 19.1% had unknown outcomes. CONCLUSIONS: Swift referral to an orofacial pain specialist is recommended for effective recovery in cases of TNI arising from endodontic treatment.

Sihler's staining of the anterior belly of digastric muscle for botulinum toxin injection.

PURPOSE: The anterior belly of the digastric muscle (ABDM) is the target of botulinum toxin injection; however, anatomical considerations related to the injection point are absent. This study used Sihler's staining to analyze the intramuscular nerve distribution of ABDM to identify the most effective botulinum toxin injection points. METHODS: We used 12 specimens from 6 embalmed cadavers in this study. The specimens were manually dissected to preserve the mylohyoid nerve and subjected to Sihler's staining. From the gnathion to and hyoid bone, the ABDM was divided into three equal parts, distinguishing the anterior, middle, and posterior thirds. RESULTS: Only a branch of the mylohyoid nerve entered the ABDM, and its entry point was located in the middle-third region in all cases. The nerve endings were concentrated in the middle third (100%), followed by the anterior third (58.3%) and were not observed in the posterior third. CONCLUSION: The landmarks used in this study (gnathion and hyoid bone) are easily palpable on the skin surface, allowing clinicians to target the most effective injection site (middle third of ABDM). These results provide scientific and anatomic evidence for injection points, and will aid in the management of ABDM injection procedures in clinical practice.