Evaluation of oxidative stress cycle in healthy and inflamed dental pulp tissue: a laboratory investigation.

OBJECTIVES: The purpose of this study was to investigate the oxidative stress cycle consisting of reactive oxygen molecules (ROS), glutathione (GSH) and glutathione S-transferase (GST) in caries-related pulp inflammation. METHODOLOGY: Fifty-four pulp tissue samples were collected from healthy donors with the diagnosis of reversible pulpitis, symptomatic irreversible pulpitis, and healthy pulp. Twelve pulp samples from each group were homogenized and total protein, ROS, GSH, and GST were measured by spectrophotometer. The remaining 6 samples from each group were prepared for paraffin block and used for the histopathologic and immunohistochemical evaluation of oxidative stress parameters and TUNEL labeling. Data were analyzed statistically. RESULTS: The results revealed that total protein levels significantly decreased; however, ROS levels increased in both reversible and irreversible pulpitis compared to the healthy pulp (p < 0.01). Also, as inflammation increases, GST enzyme levels decrease while GSH levels increase significantly (p < 0.05). It was found that the number of TUNEL (+) cells was increased in irreversible pulpitis samples compared to healthy and reversible pulpitis groups (p < 0.05). GSTP1 and GSH immunoreactivity were also observed in irreversible pulpitis samples. CONCLUSIONS: It has been revealed that caries-related inflammation alters the oxidative stress cycle in dental pulp tissue. The increase in GSH levels in the inflamed dental pulp due to the increase in ROS levels may improve the defensive ability of the dental pulp. CLINICAL RELEVANCE: There is a relationship between oxidative stress and inflammation. Control of excessive oxidative stress in pulpitis can stimulate reparative and regenerative processes. The present findings may provide an overview of the management of oxidative stress in cases with pulpitis during regenerative treatments.

Evaluation of the surface free energy on root canal dentine walls treated with chelating agents and NaOCl.

AIM: To evaluate ex vivo the effects of combined and single use of EDTA, RC-Prep and NaOCl on the surface free energy of canal wall dentine using the captive bubble technique. METHODOLOGY: Eighteen extracted human pre-molar teeth were sectioned at the crown and the apical third, the remaining mid-root portion were bisected longitudinally. Thereafter, the root halves were embedded in resin blocks that exposed the dentine surface of the canal wall. The specimens were randomly assigned to six experimental groups (n = 6) after polishing. The root dentine surfaces of the first two groups were treated with 17% EDTA or RC-Prep followed by 2.5% NaOCl irrigation. Groups 3, 4 and 5 were treated with either 17% EDTA, RC-Prep or 2.5% NaOCl alone. Control specimens were irrigated with saline solution. The surface free energies of experimental groups were calculated by measuring air and octane contact angles on the canal wall dentine. Statistical analysis was performed using the Mann-Whitney U and Bonferroni post-tests at P = 0.05. RESULTS: Compared with the control group; combined and single use of EDTA, RC-Prep and NaOCl irrigation significantly decreased the surface free energy of canal wall dentine surfaces (P < 0.05). Among all groups tested, the use of NaOCl as a final flush following RC-Prep treatment yielded increased wettability. Nevertheless, this value remained lower than that of the control group. CONCLUSION: Use of chelating agents alone or in combination with NaOCl decreased the wettability of root canal wall dentine.