The Preoperative assessment of extraction difficulty of mandibular third molar is very important for both patients and clinicians. In the last years, many new difficulty-estimating indices had been proposed, evaluating radiographical parameters alone (Kim et al. index, and Lainez et al. index) or considering additional clinical and demographic factors (Zhang et al. index and Pernambuco index). This study aimed to evaluate the effect of considering non-radiographical factors in the prediction of extraction difficulty. Four scales predicted extraction difficulty of a series of 50-impacted mandibular third molar preoperatively. The postoperative difficulty was assessed by Parant scale and the time required for surgery. The proposed indices had low to moderate sensitivity (21%-37%, 41%-67%) and variable in their specificity (21%-86%, 36%-85%). Only three out of four evaluated indices have shown a statistically significant correlation with both, the operation time and the surgical technique; namely, Lainez et al., Zhang et al., and Pernambuco indices. Considering clinical and demographic factors in preoperative difficulty assessment scales in wisdom tooth surgery may improve prediction accuracy of these scales.