Botulinum toxin type A injection into the masticatory muscles and its effects on mandibular bone resorption and density. A systematic review.

OBJECTIVE: This systematic review aims to summarize and synthesize the evidence that investigates the secondary effects of the application of botulinum toxin (BT) into the masticatory muscles and its effects on bone density. MATERIALS AND METHODS: Database searches were conducted until March 19th, 2024. The quality of the studies was assessed by the Cochrane tool risk of bias for the randomized controlled trials and the ROBINS-I tool for non-randomized studies. The Cochrane Grading of Recommendations Assessment Development and Evaluation (GRADE) was used to evaluate the confidence in the overall evidence. RESULTS: Five studies looking at the effects of botulinum toxin on bone density and resorption when applied to masticatory muscles were found. No significant changes were observed in most of the studies when looking at the effects of botulinum toxin on mandibular condyle volume, density, mandibular angle thickness, and coronoid process volume. The only finding that was statistically and clinically relevant was the difference between patients who received a double application of BT when compared with patients who received a single application (SMD: -0.99 [95%CI: -1.94,-0.05]) on the volume of the mandibular angle. CONCLUSIONS: There is no clear pattern on whether the application of botulinum toxin is associated with bone resorption or not. Although some studies show statistical significance of the findings, the magnitude of the changes in bone density and their clinical significance are not completely clear. CLINICAL RELEVANCE: To understand the effectiveness of the use of botulinum toxin into the masticatory muscles and its possible secondary adverse effects on the density of the mandible.

Guided Genioplasty: Comparison between Conventional Technique and Customized Guided Surgery.

BACKGROUND: Genioplasty as an isolated surgical technique is a highly demanded procedure in the maxillofacial surgery area. Advances in facial reconstructive surgery have been associated with less morbidity and more predictable results. In this paper, "conventional" genioplasty and genioplasty by means of virtual surgical planning (VSP), CAD-CAM cutting guides, and patient custom-made plates are compared. METHODS: A descriptive observational study was designed and implemented, and 43 patients were treated, differentiating two groups according to the technique: 18 patients were treated by conventional surgery, and 25 patients were treated through virtual surgical planning (VSP), CAD-CAM cutting guides, STL models, and titanium patient-specific plates. RESULTS: The operation time ranged from 35 to 107 min. The mean operative time in the conventional group was 60.06 + 3.74 min.; in the custom treatment group it was 42.24 + 1.29 min (p < 0.001). The difference between planned and obtained chin changes in cases of advancement or retrusion was not statistically significant (p = 0.125; p = 0.216). In cases of chin rotation due to asymmetry, guided and personalized surgery was superior to conventional surgery (p < 0.01). The mean hospital stay was equal in both groups. A decrease in surgical complications was observed in the group undergoing VSP and customized treatment. CONCLUSIONS: Multi-stage implementation of VSP with CAD-CAM cutting guides, STL models, and patient-specific plates increased the accuracy of the genioplasty surgery, particularly in cases of chin asymmetry, reducing operation time and potential complications.

Cadaveric and ultrasonographic validation of needling placement in the obliquus capitis inferior muscle.

BACKGROUND: Evidence suggests that suboccipital musculature plays an important role in headache. Proper therapeutic approaches targeting this muscle are needed. OBJECTIVE: Our aim was to determine with fresh cadavers and ultrasound imaging if a solid needle is able to properly penetrate the obliquus capitis inferior muscle during the application of dry needling. DESIGN: A cadaveric and human descriptive study. METHODS: Needling insertion and ultrasound imaging of the obliquus capitis inferior muscle was conducted on 10 pain-free healthy subjects and 5 fresh cadavers. Needling insertion was performed using a 40 mm needle inserted midway between the spinous process of C2 and transverse process of C1. The needle was advanced from a posterior to anterior direction into the obliquus capitis inferior muscle with an inferior-lateral angle to reach the lamina of C2. For the cadaveric study, the obliquus capitis inferior placement was verified by resecting the superficial upper trapezius, splenius capitis, and semispinalis capitis muscles. For ultrasographic study, a linear transducer was aligned with the long axis of the obliquus capitis inferior muscle after needle insertion. RESULTS: Both the cadaveric and ultrasonic studies showed that the needle penetrated the obliquus capitis inferior muscle during its insertion and that the tip of the needle rested against C2 laminae, thereby reaching the targeted muscle. CONCLUSION: This anatomical and ultrasound imaging study supports the assertion that needling insertion of the obliquus capitis inferior muscle can be properly conducted by an experienced clinician.