Removal of third molars is a common surgical procedure performed in maxillofacial and oral surgery. Patients with wisdom tooth extractions have the highest dental anxiety levels (1, 2). Preoperative dental anxiety results in a delay or avoidance of dental treatment and, consequently, poorer oral health and oral health-related quality of life (3, 4). Recent studies have shown that psychological anxiety leads to the activation of the body's stress reaction and slower postoperative recovery (5). Dental anxiety has also been shown to be associated with postoperative pain (5–7).

Recently, patient recovery has attracted considerable attention in the field of third molar surgery (8–12). Questionnaires on evaluating the severity of postoperative symptoms have become more useful and are widely used (13–15). Additionally, a previous study found that patient anxiety affects the difficulty of impacted lower third molar extraction (16). The surgical difficulty is frequently associated with considerable postoperative adverse effects such as pain, edema, and trismus (9, 17, 18). Previous studies have also indicated that the complexity of the surgical operation has been associated with postoperative symptoms (14). These results suggest that preoperative dental anxiety may be associated with postoperative symptoms. However, the specific relationship between preoperative dental anxiety and the severity of postoperative symptoms remains unclear.

Several studies have evaluated the association between dental anxiety and LM3 surgery (19–21). Patients with high dental anxiety experience greater trismus and more pain (19). Onwuka et al. reported that preoperative dental anxiety is more common in women (21). However, confounding factors have not been fully incorporated into multivariable regression models for control (19). A direct independent association between preoperative dental anxiety and postoperative symptoms in patients undergoing lower third molar removal is still unestablished. Moreover, the significance of the non–linear relationship still requires further clarification. Therefore, exploring the non–linear relationships between anxiety and postoperative symptoms using non–linear methods is important.

The present study assessed the relationship between preoperative dental anxiety and postoperative symptoms after lower third molar (LM3) extraction surgery.

A total of 213 patients were enrolled in this study (Figure 1). The baseline patient characteristics are shown in Table 1. The proportion of dental anxiety was as follows: No anxiety, 7.5%; Some unease, 46.9%; Anxious, 31.0%; Very anxious, 14.6%; Overall, the mean (SD) dental anxiety score was 10.56 (3.57), the median (IQR) age was 27.5 (22.0–31.5) years, and 35.7% (76 of 213) were males. The mean (SD) dental anxiety score was 10.22 (3.94) in males and 10.75 (3.34) in females.

The DAS-TMS revealed good internal consistency (Cronbach's α = 0.905) and temporal stability (ρ = 0.67; p < 0.001). The score was significantly correlated with the IDAF-4C score (ρ = 0.63, p < 0.001), supporting good criterion-related and discrimination validity. For construct validity, the CFA revealed that the data from the DAS-TMS fit well with the two-factor model (χ² = 0.654, P = 0.419, with a root mean square error of approximation = 0, comparative fit index = 1.001, goodness of fit index = 0.998, normed fit index = 0.999).

The prevalence of serious postoperative symptoms across the categories of DAS-TMS scores was 2.8% for 4–5 points, 45.3% for 6–10 points, 34.9% for 11–15 points, and 17.0% for 16–20 points. The distribution of DAS-TMS based on sex was statistically significant (P = 0.02). Age, Winter classification, Pell-Gregory occlusal position, Pell-Gregory ramus classification, and operation time were not significantly different across the categories of DAS-TMS (all P values > 0.05) (Table 1).

As shown in Table 2, a higher DAS-TMS level was associated with a higher incidence of postoperative symptoms before multivariate adjustment (Table 2). The multivariate-adjusted ORs (95% CIs) for postoperative symptom severity across categories of DAS-TMS were 1, 3.63 (0.90, 14.68), 5.29 (1.25, 22.33), and 4.75 (1.02, 22.18). The results of the secondary analysis did not significantly change the estimated associations (Figure 2). The forest plot for DAS-TMS with postoperative symptoms as a continuous variable is shown in Figure 3.

After adjusting for these possible factors related to postoperative symptoms, a non–linear relationship between DAS-TMS and postoperative symptoms was observed (Figure 4). The risk of serious postoperative symptoms increased with the dental anxiety level up to 7 points (adjusted OR 1.94, 95% CI 1.12–3.74; P = 0.012). When the dental anxiety level exceeded 7 points, the level of DAS-TMS was not associated with the risk of serious postoperative symptoms (OR 0.98, 95% CI 0.88–1.08; P = 0.756) (Table 3).

Dental anxiety is a common problem in patients undergoing third molar extraction (30). Dental anxiety is a significant problem for both patients and dental professionals. Information provided to the patient and dentist concerning dental anxiety is important and based on scientific evidence. Our findings indicate that dental anxiety is associated with postoperative symptoms during third molar extraction surgery. Previous studies indicated that dental anxiety is associated with surgical difficulties and postoperative pain (5, 6, 19). Management of postoperative complications is important for faster recovery. Identifying the relationship between preoperative dental anxiety and associated postoperative symptoms can help minimize and prevent postoperative complications.

Patients with high dental anxiety often require longer operation times (19). Studies have also reported that operation time is related to postoperative analgesia and the severity of postoperative complications (13). The “Very anxious” category of dental anxiety was associated with a high incidence of postoperative symptoms (OR 4.75, 95% CI 1.02–22.18) after multivariate adjustments. This also supports the conclusion that preoperative anxiety is related to postoperative symptoms. The effect of dental anxiety on the risk of serious postoperative symptoms weakened after additional adjustment, indicating that these confounders may be associated with serious postoperative symptoms.

Our results may be due to inflammatory reactions. Preoperative dental anxiety can lead to the change of prostaglandin E2 (PGE2) (31, 32). PGE2 is thought to enhance inflammation by causing vasodilation and increasing the local blood flow (33). An increase in blood PGE2 concentration caused by preoperative anxiety may affect the severity of postoperative complications. Additionally, preoperative anxiety can significantly change the release of Serotonin (5-HT) (34), which is manifested by the increased secretion of 5-HT by platelets, mast cells, and chromaffin cells. Among them, 5-HT3 can directly excite nociceptors or sensitize them through the internal messenger system. 5-HT2A acts on 5-HT2A receptors at the terminals of primary afferent fibers, resulting in aggravation of pain and edema.

In our research center, 54.4% of the patients had a DAS-TMS score of 10 or less. Our research showed that preoperative anxiety is related to the severity of postoperative symptoms. More importantly, the data further show that the risk of severe postoperative symptoms increases with an increase in DAS-TMS levels of up to 7 points. It also shows that early intervention for preoperative dental anxiety is significant in preventing the occurrence of severe postoperative symptoms. Whether the use of preoperative anxiolytic drugs affects postoperative symptoms merits further exploration.

This study has several limitations. First, the sample was selected from only one local hospital. The patients included in this study were relatively young, which may have caused a selection bias. The representativeness of the sample might be limited, and our results may have poor generalizability. Second, the exposure and outcome variables were collected through self–completed questionnaires, which may not reflect the real situation. Third, despite controlling and adjusting many confounders, the existence of residual confounding factors may have affected the results.

Our findings suggest that preoperative dental anxiety is associated with a risk of serious postoperative symptoms following LM3 extraction surgery. The degree of dental anxiety in patients before LM3 extraction surgery should be of concern to clinicians.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Ethics Committee of Stomatology Hospital of Tianjin Medical University (Tianjin, China) (No: TMUhMEC20210508). The patients/participants provided their written informed consent to participate in this study.

FQ and DZ contributed to the study concept and design. Material preparation, data collection and analysis was performed by FQ, MZ, and TZ. The first draft of the manuscript was written by FQ. All authors contributed to the article, commented on previous versions of the manuscript and approved the submitted version.

This work was supported by the Science and Technology Project of Tianjin Health Committee (Grant Number: ZC20134) and the Joint Research Fund of Tianjin Medical University-DeepWise Health care (Grant Number: 1KQ026).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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