Correlations between additional roots in maxillary second molars, maxillary first premolars, mandibular first molars and mandibular first premolars: a retrospective cone-beam computed tomography analysis

This study aimed to determine the prevalence of additional roots in maxillary second molar (MSM), maxillary first premolar (MxFP), mandibular first molar (MnFM) and mandibular first premolar (MnFP) teeth and evaluate the correlations between the number of roots for these teeth. Images of 630 Turkish patients, in which all dental groups examined in the study were present bilaterally, were analyzed using cone-beam computed tomography. The images for the presence of the fourth root in MSMs, third root in MxFPs, distolingual root in MnFMs and complicated-root structure in MnFPs were assessed and divided additional roots into subgroups. The Chi-square test was used for categorical variables such as sex and tooth position. Logistic regression analysis was performed to understand the predictor variability of other teeth in teeth with extra roots. A p < 0.05 was considered statistically significant. Prevalence of the fourth root in MSMs was 1.75%, third root in MxFPs was 6.35%, third root in MnFMs was 3.57%, and complicated root in MnFPs was 21.9%. Positive correlations were observed between MSM, MxFP and MnFP teeth for increasing root numbers (P < 0.05). There was no significant correlation between root numbers of MnFM teeth and other tooth groups (P > 0.05) In the tooth groups examined, there was at least one explanatory variable (except for the right MnFM) tooth in addition to the contralateral tooth for the presence of additional roots.