Comparative Histopathological Spectrum of Periapical Lesions in Root Canal-Treated and Non-root Canal-Treated Teeth

Periapical lesions represent a spectrum of inflammatory and pathological changes associated with endodontic infection. The histopathological characteristics may differ according to the previous root canal treatment status of the associated tooth. This study aimed to compare the histopathological spectrum and predominant inflammatory patterns of periapical lesions in root canal-treated (RCT) and non-root canal-treated (non-RCT) teeth.

A comparative cross-sectional histopathological study was conducted on 120 periapical tissue specimens comprising 60 RCT and 60 non-RCT specimens. Specimens were obtained during periapical surgery or extraction and examined histopathologically using hematoxylin and eosin staining. The histopathological diagnoses were categorized as periapical granuloma, radicular cyst, periapical abscess, or other/indeterminate. Predominant inflammation was classified as chronic, acute, or mixed acute-on-chronic inflammation. Two blinded oral and maxillofacial pathologists independently evaluated the specimens, and interobserver agreement was assessed using Cohen's kappa. Categorical variables were analyzed using chi-squared or Fisher's exact tests, with odds ratios (ORs) and 95% confidence intervals (CIs) calculated for the individual diagnostic categories.

The mean age was 36.67±10.18 years in the RCT group and 36.86±10.00 years in the non-RCT group (p=0.917). Periapical granuloma occurred in 20 (33.3%) RCT and 32 (53.3%) non-RCT specimens (OR=0.44; 95% CI: 0.21-0.92; p=0.042), whereas radicular cysts occurred in 28 (46.7%) and 14 (23.3%), respectively (OR=2.88; 95% CI: 1.31-6.30; p=0.012). Periapical abscess occurred in eight (13.3%) RCT and 10 (16.7%) non-RCT specimens (OR=0.77; 95% CI: 0.28-2.11; p=0.799). Predominantly, chronic inflammation was observed in 34 (56.7%) RCT and 22 (36.7%) non-RCT specimens, whereas acute inflammation occurred in 8 (13.3%) and 20 (33.3%) specimens, respectively (χ²=7.71; p=0.021). Interobserver agreement was almost perfect for histopathological diagnosis (κ=0.874) and substantial for inflammatory patterns (κ=0.805).

Periapical lesions associated with RCT and non-RCT teeth demonstrated significant differences in histopathological diagnosis and inflammatory patterns. Radicular cysts were more frequent in RCT teeth, whereas granulomas and acute inflammation were more frequent in non-RCT teeth than in RCT teeth. Histopathological assessment provides valuable diagnostic information regarding persistent periapical lesions.