IADR Abstract Archives
Effect of Botulinum Toxin-a on Mandibular Bone: Systematic Review/Meta-Analysis
Objectives: Botulinum Toxin-A (BTX), one of the most potent toxins known to man, is used in dental practice to temporarily paralyse muscles and reduce hyperfunction implicated in temporo-mandibular disorders (TMDs). BTX use in TMDs remains off-label and potential adverse effects are understudied. In animal models of paralysis, BTX is known to induce significant bone loss. The objective of this study is to systematically review the literature for articles investigating changes in mandibular bone structure following BTX injections and meta-analyse available data on reported bone outcomes.
Methods: Comprehensive search of 3 databases retrieved 934 articles. Following screening, 20 articles quantitatively describing changes in mandibular bone structure after BTX injection in masseter and/or temporalis muscles in humans (6 articles), rabbits, rats or mice (14 articles) were included. Study charachterstics and covariates were identified and tabulated. Means and variance of meta-analyzable parameters were collected and effect sizes calculated. Meta-analysis was conducted using random effects model and heterogeniety was assessed.
Results: For humans, 86% of participants received BTX for myofascial TMDs, with 96% of all participants being females 27 – 55 years of age. For animals, injections in young to skeletally mature mice, rats and rabbits were reported, with balanced male/female ratio. BTX doses varied from 0.2-10U in animal studies, and 50-240U for human participants. Meta-analysis of human participant data revealed decreased cortical thickness of mandibular regions following BTX injection, with percent difference compared to baseline being -9.0% [Confidence Interval (CI);-15.3; -2.7], while bone volume was not significantly affected (-2.5%[-13.0; 7.9]). Subgroup analysis by mandibular regions suggested higher cortical bone loss in condyle. In animals, significant loss of mandibular cortical thickness (-12.3%[-18.9; -5.6]) and trabecular density (-40.9%[-50.0; -31.8]) in BTX-injected compared to contralateral site.
Conclusions: We demonstrated that BTX injection in the masticatory muscles induced mandibular bone loss in human participants and in animal models. Data scarcity was evident for all species. Meta-analytic estimates of the effect size and variance produced in this study will help in designing future trials.
Methods: Comprehensive search of 3 databases retrieved 934 articles. Following screening, 20 articles quantitatively describing changes in mandibular bone structure after BTX injection in masseter and/or temporalis muscles in humans (6 articles), rabbits, rats or mice (14 articles) were included. Study charachterstics and covariates were identified and tabulated. Means and variance of meta-analyzable parameters were collected and effect sizes calculated. Meta-analysis was conducted using random effects model and heterogeniety was assessed.
Results: For humans, 86% of participants received BTX for myofascial TMDs, with 96% of all participants being females 27 – 55 years of age. For animals, injections in young to skeletally mature mice, rats and rabbits were reported, with balanced male/female ratio. BTX doses varied from 0.2-10U in animal studies, and 50-240U for human participants. Meta-analysis of human participant data revealed decreased cortical thickness of mandibular regions following BTX injection, with percent difference compared to baseline being -9.0% [Confidence Interval (CI);-15.3; -2.7], while bone volume was not significantly affected (-2.5%[-13.0; 7.9]). Subgroup analysis by mandibular regions suggested higher cortical bone loss in condyle. In animals, significant loss of mandibular cortical thickness (-12.3%[-18.9; -5.6]) and trabecular density (-40.9%[-50.0; -31.8]) in BTX-injected compared to contralateral site.
Conclusions: We demonstrated that BTX injection in the masticatory muscles induced mandibular bone loss in human participants and in animal models. Data scarcity was evident for all species. Meta-analytic estimates of the effect size and variance produced in this study will help in designing future trials.