Salivary antioxidant enzymes associated with oral toxicity in haematopoietic cell transplantation: An observational study.

BACKGROUND: In haematopoietic cell transplantation (HCT), oral mucositis and xerostomia are related to conditioning-related oxidative stress. The role of salivary antioxidant enzymes in oral toxicity is poorly described. The aim of this study was to verify the association between salivary antioxidant enzymes and oral mucositis and xerostomia in HCT. DESIGN: Saliva from autologous and allogeneic HCT patients (n = 77) was selected before conditioning (T0), during the neutropenia period (T1) and after marrow engraftment (T2). Salivary flow, total salivary proteins, and superoxide dismutase, catalase and glutathione reductase activities were measured. RESULTS: There were no significant differences in salivary flow, total salivary proteins and catalase at the three HCT time points. Glutathione reductase levels were reduced at T1 compared to T0 (P = .013) and T2 (P = .001). Superoxide dismutase levels were increased from T0 to T2 (P = .013). Neither of these enzymes was associated with oral mucositis. Increased superoxide dismutase levels were associated with xerostomia frequency. Levels of this enzyme also showed significant correlation with days of xerostomia in T2 (ρ = .40, P = .002). CONCLUSIONS: Salivary antioxidant enzymes changed before and during early periods after HCT. The increase in salivary superoxide dismutase suggested partial activation of the salivary antioxidant system and was associated with xerostomia.

In vitro evaluation of enamel demineralization after Er:YAG and Nd:YAG laser irradiation on primary teeth.

OBJECTIVE: This in vitro study evaluated the influence of both Er:YAG and Nd:YAG laser irradiation on deciduous enamel demineralization. BACKGROUND DATA: Although there are still few studies on the use of the high-intensity laser for caries prevention in deciduous teeth, it is believed that its use on the dental structure can lead to a more acid-resistant surface. METHODS: Forty enamel samples obtained from 22 deciduous first molar teeth were ground and randomly divided into four groups (n = 10): group 1 (G1), no treatment (negative control); G2, fluoride (positive control); G3, Er:YAG laser (2 Hz, 60 mJ, 40.3 J/cm(2)); G4, Nd:YAG laser (80 mJ, 10 Hz, 0.8 W). After the surface treatment, the samples were submitted to an acid challenge that consisted of a 5-day immersion in demineralizing (3 h) and remineralizing solution (21 h). Next, a microhardness test was preformed. RESULTS: Analysis of variance (ANOVA) and Student Newman Keuls tests were performed (alpha = 5%). The percentage of lesion inhibition for each group was as follows: G2, 59.4%; G3, 35.7%; and G4, 40.4%. As regards the percentage loss of mineral volume, there was no statistical difference between groups G2 (444.37 +/- 146.42) and G3 (441.81 +/- 207.08) when compared with group G1 (281.03 +/- 134.57). All experimental groups presented a lower mineral loss compared with the non-irradiated samples (G4). CONCLUSION: The findings of the present study revealed that both Nd:YAG and Er:YAG lasers can be an alternative tool for enhancing deciduous enamel acid resistance.