Is canal overinstrumentation able to produce apical root dentinal microcracks in extracted teeth?

AIM: To assess the impact of mechanical overinstrumentation of root canals in extracted teeth on the development of dentinal microcracks in the apical portion of the root by means of micro-computed tomographic (micro-CT) analysis. Root canal preparation short of the canal terminus and at the apical foramen (AF) were used as controls. METHODOLOGY: Twenty 2-rooted maxillary premolars with two canals were selected, scanned in a micro-CT device and the root canals prepared sequentially using Reciproc M-Wire R25 instruments to working lengths: 1 mm short of the AF (AF - 1 mm), at the AF (AF), and overinstrumentation (AF + 1 mm). A micro-CT scan of each specimen was performed after each time point. After reconstruction and co-registration procedures, the images were screened from the cementoenamel junction to the apex (n = 55 352) to identify the presence of dentinal microcracks in the apical third of the root. RESULTS: After the analyses of 55 352 slices, dentinal microcracks were visualized in 12.45% of the images (6892 slices), with 5.73% (3174 slices) in the cervical, 3.57% (1976 slices) in the middle and 3.15% (1740 slices) in the apical third. All dentinal microcracks observed at all time points (AF - 1 mm, AF and AF + 1 mm) were already present in the corresponding images before canal instrumentation. Therefore, no new microcracks were detected, regardless of the working length used for canal instrumentation. CONCLUSION: Reciprocating root canal preparation either short, at or beyond the AF (overinstrumentation) did not create dentinal microcracks in the roots of extracted 2-rooted maxillary premolars.

Association between chronic apical periodontitis and low-birth-weight preterm births.

INTRODUCTION: The objective of this study was to investigate the association between chronic apical periodontitis (CAP) and low-birth-weight preterm births (LBWPB). METHODS: Sixty-three women in postpartum period were included in this case-control study. The case group consisted of mothers of LBWPB infants (n = 33), and the control group was represented by mothers of newborns at term (n = 30). The CAP diagnosis was performed by using periapical radiographs through the periapical index in postpartum period. The χ(2) test, Fisher exact test, and linear and logistic regression were used for statistical analysis. RESULTS: It was observed that CAP was present in 54.5% of mothers in the case group and 20.0% in the control group (P = .004); postpartum women with CAP had about 3.5 times greater odds of LBWPB newborns than women without CAP (adjusted odds ratio, 3.52; 95% confidence interval, 1.01-12.32). Postpartum women who reported 6 or more prenatal consultations reduced odds of LBWPB newborns in 80% (adjusted odds ratio, 0.20; 95% CI, 0.06-0.69). It can be estimated that the increase of 1 unit of periapical index had a significant association with the reduction of 1½ gestational weeks in the crude analysis (ß = -1.5, P = .010) and the reduction of 211 g in birth weight after the adjusted analysis (ß = -211, P = .058). CONCLUSIONS: Prematurity and low birth weight were associated with radiographically detected CAP. Women with CAP in postpartum period had greater odds of LBWPB.