Department of Oral and Maxillofacial Surgery, Jiangyin People's Hospital Affiliated to Nantong University, No.163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China.
Department of Oral Mucosal Diseases, The Affiliated Stomatological Hospital of Nanjing Medical University, 136 Hanzhong Road, Nanjing, 210000, Jiangsu, China.
BMC Oral Health. 2023 Jul 18;23(1):499. doi: 10.1186/s12903-023-03179-5.
Observational studies have shown that body mass index (BMI) is highly correlated with the occurrence of temporomandibular disorders (TMDs). However, these studies failed to present a causal relationship. Thus, we aimed to performed a Mendelian randomization (MR) study to investigate causality between BMI and TMDs.
We performed a two-sample bidirectional MR analysis using large-scale genome-wide association studies (GWAS). Data were obtained from a large-scale BMI dataset (N = 322,154), TMDs dataset (N = 134,280). The causal effects were estimated with inverse-variance weighted (IVW) method, MR Egger, weighted median. Sensitivity analyses were implemented with Cochran's Q test, MR-Egger intercept test, MR-PRESSO, leave-one-out analysis and the funnel plot.
In the forward MR analysis, a genetic prediction of low BMI was causally associated with a higher risk of TMDs (IVW OR: 0.575, 95% CI: 0.415-0.798, p: 0.001). Similar results were obtained using other complementary methods (MR Egger OR: 0.270, 95% CI: 0.104-0.698, p: 0.009; weighted median OR: 0.496, 95% CI: 0.298-0.826, p: 0.007). In the reverse MR results, TMDs was shown to have no significant effect on BMI (all p > 0.05). No pleiotropy and heterogeneity were detected in the bidirectional analysis (p > 0.05).
A lower BMI might be causally associated with increased risk of TMDs, supporting the importance of weight control for the prevention of TMDs. Clinicians should pay more attention to the low-BMI patients among those seeking medical advice due to temporomandibular joint discomfort.
观察性研究表明，体重指数（BMI）与颞下颌关节紊乱（TMD）的发生高度相关。然而，这些研究未能表明两者之间存在因果关系。因此，我们旨在进行孟德尔随机化（MR）研究，以探讨 BMI 与 TMD 之间的因果关系。
我们使用大规模全基因组关联研究（GWAS）进行了两样本双向 MR 分析。数据来自大规模 BMI 数据集（N=322154）和 TMD 数据集（N=134280）。使用逆方差加权（IVW）法、MR Egger、加权中位数来估计因果效应。采用 Cochran's Q 检验、MR-Egger 截距检验、MR-PRESSO、逐一剔除分析和漏斗图进行敏感性分析。
在正向 MR 分析中，低 BMI 的遗传预测与 TMD 风险增加相关（IVW OR：0.575，95%CI：0.415-0.798，p=0.001）。使用其他互补方法也得到了类似的结果（MR Egger OR：0.270，95%CI：0.104-0.698，p=0.009；加权中位数 OR：0.496，95%CI：0.298-0.826，p=0.007）。在反向 MR 结果中，TMD 对 BMI 没有显著影响（均 p>0.05）。双向分析中未检测到明显的异质性（p>0.05）。
较低的 BMI 可能与 TMD 风险增加存在因果关系，支持控制体重对于预防 TMD 的重要性。对于因颞下颌关节不适而就诊的患者，临床医生应更加关注低 BMI 患者。
