Hydrogen peroxide penetration into the pulp chamber during conventional in-office bleaching and diode laser-assisted bleaching with three different wavelengths

BACKGROUND AND AIMS

Penetration of hydrogen peroxide into the pulp chamber and subsequent tooth hypersensitivity is a common concern in dental bleaching. The aim of this study was to assess the penetration of hydrogen peroxide (H2O2) into the pulp chamber in diode-laser activated bleaching with different laser wavelengths.

MATERIALS AND METHODS

Fifty extracted human maxillary anterior teeth were collected and divided into five groups(n = 10). Group 1: conventional in-office bleaching using Opalescence Boost gel. Group 2: Bleaching with Biolase Laser White 20 gel activated by 980 nm diode laser. Group 3: Bleaching with Biolase Laser White 20 gel activated by 810 nm diode laser. Group 4: Bleaching with Biolase Laser White 20 gel activated by 940 nm diode laser. Group 5: No bleaching control group.After bleaching, the solution into the pulp chamber was collected and analyzed using a spectrophotometer. The recorded data were compared with a standard sample and the results were analyzed and compared using one-way ANOVA and Tukey's HSD tests.

RESULTS

In all bleached groups, H2O2 had infiltrated into the pulp chamber. The highest level of penetration was noted in group 2 (2.32 ± 0.25 µg), while the lowest level was noted in group 3 (1.85 ± 0.33 µg). The difference in this regard was significant between groups 2 and 3 (P = 0.024), but the differences between other groups were not statistically significant (P ≥ 0.42).

CONCLUSION

Considering the results of this study, it can be stated that hydroge peroxide penetration in to pulp chamber in diode laser activation of bleaching agent according to manufactures instruction is not higher than in-office bleaching. The wavelength of diode laser had significant effect on penetration of hydrogen peroxide into pulp chamber.

Protein tyrosine phosphatase 1B (PTP1B) is required for cardiac lineage differentiation of mouse embryonic stem cells

Protein tyrosine phosphatase 1B (PTP1B) has been shown to regulate multiple cellular events such as differentiation, cell growth, and proliferation; however, the role of PTP1B in differentiation of embryonic stem (ES) cells into cardiomyocytes remains unexplored. In the present study, we investigated the effects of PTP1B inhibition on differentiation of ES cells into cardiomyocytes. PTP1B mRNA and protein levels were increased during the differentiation of ES cells into cardiomyocytes. Accordingly, a stable ES cell line expressing PTP1B shRNA was established. In vitro, the number and size of spontaneously beating embryoid bodies were significantly decreased in PTP1B-knockdown cells, compared with the control cells. Decreased expression of cardiac-specific markers Nkx2-5, MHC-α, cTnT, and CX43, as assessed by real-time PCR analysis, was further confirmed by immunocytochemistry of the markers. The results also showed that PTP1B inhibition induced apoptosis in both differentiated and undifferentiated ES cells, as presented by increasing the level of cleaved caspase-3, cytochrome C, and cleaved PARP. Further analyses revealed that PTP1B inhibition did not change proliferation and pluripotency of undifferentiated ES cells. Taken together, the data presented here suggest that PTP1B is essential for proper differentiation of ES cells into cardiomyocytes.

Suitable bone markers assessing bone status in patients with both coronary artery disease and diabetes

Background

We aimed to investigate the bone turnover markers in coronary artery disease (CAD) patients with and without type 2 diabetes (T2DM) in comparison with control subjects without CAD and T2DM.

Methods

This cross-sectional study was performed on 45 subjects undergoing elective heart surgery; either for coronary artery bypass grafting or for valve surgery. According to angiographic results, participants were grouped in two groups with CAD (n = 33) and without CAD (n = 12).

The serum levels of osteocalcin (OC), procollagen I aminoterminal propeptide (P1NP) and carboxy-terminal collagen crosslinks (CTX), as bone turnover markers, as well as serum levels of 25 (OH) vitamin D3, PTH, and common metabolic factors were analyzed in all participants.

Results

Serum levels of bone markers did not differ in patients with CAD compared to non-CAD subjects. Regarding metabolic factors, serum levels of FBG had invert correlation with OC in CAD patients (p = 0.004). The data of subgroup analysis showed serum levels of OC and CTX were statistically significant lower in CAD-DM than CAD-non DM (p < 0.05). There were not any significant differences in the P1NP levels between groups.

Conclusions

Our data suggest that CTX and OC would be used as suitable bone markers in CAD patients with T2DM. However, further clinical studies need to establish the role of these markers in CAD patients with diabetes.