Prevalence of Radicular Sclerotic Dentin in Young and Old

Objectives: Size of apical enlargement has been controversial. One strong argument for a larger apical preparation is to facilitate apical healing by mechanically removing infected apical dentin. Radicular sclerotic dentin (rSD) is highly mineralized and it has been shown to prevent the penetration of root canal sealers. Our central hypothesis is that the presence of rSD could also prevent bacterial penetration. To begin testing this hypothesis, the prevalence of rSD was examined in this project.
Methods: Extracted teeth from two age groups (Y: <30-year; O: >60-year) with the presence (I) or absence (H) of apical radiolucency on radiographs were collected, prepared and processed for H & E staining. The location of rSD in apical 1/3 (A), middle 1/3 (M) and cervical 1/3 (C) of each root was identified on longitudinal sections. Data were analyzed using a logistic regression split-plot model with fixed effects age and location for comparing OI (N=9) with YI (N=11).
Results: A significantly higher prevalence (p=0.0071) of rSD was observed in OI (84.0%) than YI (8.2%) with a high preference in A (95.4%) than M (36.8%, p<0.0001) or C location (2.6%, p<0.0001). Effects of apical radiolucency and location of rSD were analyzed similarly when comparing OH (N=8) with OI (N=9). There was no difference in rSD prevalence between OH (96.4%) and OI (79.8%). Both O groups exhibited a higher prevalence of rSD in A (99.6%) than M (93.8%, p=0.0024) or C location (21.1%, p<0.0001).
Conclusions: Apical 1/3 has the highest prevalence of rSD than its corresponding M and C locations in our samples. The severity of periapical destruction does not seem to affect the prevalence of rSD in O groups. A higher prevalence of rSD in apical location in O groups would support a smaller apical preparation if rSD in apical 1/3 could prevent bacterial invasion of dentinal tubules.