Effect of chlorhexidine and benzalkonium chloride on the long-term push-out bond strength of fiber posts.

Background and Aim: Fiber posts are widely used in endodontically treated teeth with extensive loss of coronal structure. The purpose of this study was to investigate immediate and the long-term effects of chlorhexidine (CHX) and benzalkonium chloride (BAC) application, on the push-out bond strength of fiber posts. Material and Methods: Sixty mandibular premolars were decoronated, and root canal treatment was performed. After post space preparation, the specimens were divided into three groups according to the post space-surface pretreatment (n = 20); no surface treatment (control group-Group 1), 2% CHX application (Group 2), and 1% BAC application (Group 3). A self-curing adhesive cement and an etch and rinse adhesive were used for the cementation of posts. Three sections (one cervical, one middle, and one apical) of 1 mm thickness were prepared from each specimen. A push-out test was performed immediately on the half of the specimen sections (n = 10). The other half of the specimen sections were subjected to 20.000 thermal cycles before applying the push-out test (n = 10). The failure mode of each specimen was observed under a stereomicroscope at ×40 magnification. Results: The data were analyzed by one-way analysis of variance (ANOVA), Tukey Honestly significant difference (HSD), and Tamhane tests (P = 0.05). The cervical thirds displayed the highest, and the apical thirds showed the lowest values in all groups (P < 0.05), except the control-aged group (P = 0.554). The aged control groups' values were found to be significantly lower than the aged CHX and BAC groups (P < 0.001). Aging significantly reduced the bond strength values of specimens in control groups (P < 0.001). However, aging did not significantly affect the push-out bond strength values of CHX and BAC groups (P > 0.050). The failure types were adhesive between the post and cement (type 1) in all groups, except control-aged group (type 2). Conclusion: The application of 2% chlorhexidine or 1% BAC may be an essential step that can be taken to preserve the bond strength of fiber posts.

The frequency of sodium hypochlorite extrusion during root canal treatment: an observational clinical study.

BACKGROUND: To determine the frequency of sodium hypochlorite (NaOCl) extrusion and evaluate the outcome of the injury. METHODS: A total of 1123 teeth indicated root canal treatment were included. An open-ended needle was used during/after the instrumentation. Acute burning pain during irrigation was considered as NaOCl extrusion. Negative aspiration was applied for patients with extrusion, and appropriate treatment was planned due to the symptoms. The number of patients who experienced extrusion and symptoms were recorded. Analysis of variance (ANOVA), at P < 0.05, was used to compare the data groups. RESULTS: NaOCl extrusion rate was found at 0.89%, and the injury with swelling that differential diagnosis of NaOCl accident caused by extrusion rate was 0.18%. The most common findings besides acute pain, as a sign of extrusion (n = 10), were accompanying apical bleeding (n = 6) and swelling (n = 2). According to the number of visits, a significant correlation was found between the symptoms (P = 0.010). No serious injury such as a neurological sign, tissue necrosis or trismus occurred in any patient. CONCLUSIONS: Demographic characteristics of the patients and preoperative condition of teeth were not related to NaOCl extrusion. The increasing number of visits may affect the probability of an accident. Negative aspiration immediately may be crucial in preventing severe injuries.