Primarily, the intensity of local anesthesia (LA) in mandibular third-molar (M3) surgery is governed directly by lipid solubility of the local anesthetic drug and indirectly by other physical characteristics. However, a patient's demographic, anthropometric, behavioral, and surgical factors may affect these physical characteristics and, therefore, indirectly influence the clinical actions of the local anesthetic drug used. The aim of this study was to investigate patients’ demographic, anthropometric, behavioral, and surgical variables that may predict for the intensity of LA in mandibular M3 surgery among healthy adult patients.

This cross-sectional study included 141 patients with unilateral mandibular M3 teeth indicated for surgical extraction under LA. Patients’ demographic, anthropometric, behavioral, and surgical potential predictor variables were recorded. Lidocaine (2%) with epinephrine (1:100,000) was administered to provide block anesthesia for mandibular M3 surgery. The overall intra-operative pain (intensity of LA) was the outcome variable and was evaluated by the patient after surgery, using a visual analogue scale (VAS). Data were analyzed using univariate analysis and multivariate regression analysis.

The final study population comprised 126 participants: 80 women and 46 men (mean age±SD=29.2±12.3 year). With multivariate regression analysis, age, smoking quantity, and “amount of local anesthetic used” were the only significant (P<0.001) predictors of the intensity of LA in mandibular M3 surgery.

This study suggested that an increase in age, smoking quantity and “amount of local anesthetic used” would predict an increase in the intensity of LA in mandibular M3 surgery.