Objective To explore the risk factors of temporomandibular disorders (TMD) in patients with mandibular third molar impaction, and to establish a risk nomogram model.

Methods A total of 209 patients with mandibular third molar impaction were selected and divided into TMD group (n=54) and non-TMD group (n=155) based on the occurrence of TMD.Univariate analysis and multivariate logistic regression analysis were used to analyze the risk factors of TMD, and a nomogram prediction model was established.

Results Univariate analysis showed that there were significant differences in gender, Pell-Gregory classification, unilateral mastication, and SAS scores between the two groups (P < 0.05 to P < 0.01).Multivariate logistic regression analysis showed that female, type Ⅲ impaction, low impaction, unilateral mastication and SAS scores more than 50 points were independent risk factors for TMD in patients with mandibular third molar impaction (P < 0.05 to P < 0.01).Based on this, a TMD risk nomogram model was established.The model verification results showed that the C-index was 0.745, the calibration curve was almost the ideal curve, the area under the ROC curve was 0.753 (95%CI: 0.714-0.792), and the nomogram had a net benefit of 10%-75%.

Conclusions Female, type Ⅲ impaction, low impaction, unilateral mastication and SAS scores more than 50 points increase the risk of TMD in patients with mandibular third molar impaction.Nomogram model based on this can effectively predict the risk probability of TMD in patients with mandibular third molar impaction.