Association between bacterial load and volumetric bone loss in teeth with persistent apical periodontitis: A cone‐beam computed tomography segmentation‐based observational study

AIM: To quantitatively compare the bacterial DNA load in root apices and periapical lesions surgically retrieved from teeth with failed root canal treatment, and to investigate the association between bacterial DNA load in both anatomical locations and the three-dimensional (3D) volumetric extent of periapical bone loss, as well as relevant clinical and demographic variables. METHODOLOGY: Root apices and periapical lesions were surgically obtained from patients with failed root canal treatments. Samples were cryopulverized and bacterial DNA was quantified by q-PCR assay. The volume of the periapical lesions was calculated by cone-beam computed tomography (CBCT) images segmentation using Blue Sky Bio software. Demographic and clinical data including gender, age, previous retreatment, tenderness to percussion, tooth position, and periapical healing after 1 year were preliminarily associated with the lesion volume. Normality of the variables was analyzed by the Shapiro Wilk test, and global comparisons were explored by ANOVA when variances were similar. The Student t test was used for pair-by-pair comparisons. RESULTS: Seventy-nine samples (40 root apices and 39 lesions) were successfully amplified. A greater number of DNA copies was found in apices as compared with apical lesions (p < 0.05). Analysis by lesion volume showed that a higher bacterial load in apices was associated with larger apical lesions, as well as in lesions of patients under 50 years old (p < 0.05). Clinical parameters such as tooth position and patient age showed an association with the volume of apical lesions (p < 0.05). CONCLUSIONS: Root apices harbour higher bacterial DNA than periapical lesions, regardless of the volume of apical bone loss. Apices associated with large volume lesions present a greater amount of bacterial DNA. Preliminary associations were identified between certain clinical and demographic factors (age and tooth position) and increased lesion volume.