Indigenous tooth powders = Covert lead poisoning.

Aim: The present study aimed to measure the concentration of lead in various indigenous preparations of tooth powders available and used locally in and around Udaipur, Rajasthan, India. Materials and Methods: Seven different brands of tooth powders manufactured and/or marketed locally were obtained from stores all over Udaipur city. Some home‑made powders commonly used for cleaning teeth were also collected. The tooth powders were analyzed for lead content by atomic absorption spectrophotometry. Results: All tooth powders tested were found to contain high levels of lead ranging from 21 ppm to 82 ppm, above the maximum permissible level of 20 ppm prescribed by the Bureau of Indian Standards. Conclusion: Indigenous tooth powders contain high levels of lead and thus may be a source of lead poisoning that is often overlooked.

Sealing ability and thermal diffusivity of cavity lining materials: an in vitro study.

AIMS: The purpose of this study was to evaluate and compare the sealing ability and the thermal insulating capability of four different cavity lining materials. MATERIALS AND METHODS: Forty noncarious human mandibular second premolars that were extracted for orthodontic treatment were collected, cleaned, and stored in distilled water. These premolars were randomly divided into four groups of ten teeth each for treatment with the different cavity lining materials. Group I teeth were treated with cavity varnish, group II teeth with amorphous calcium phosphate (ACP), group III teeth with dentin bonding agent, and group IV teeth with resin-modified glass ionomer cement (RMGIC). Electrical resistance and the difference in the time-temperature curve of the external surface and the pulp side [A D -A P ] of each tooth following heat and cold application for 120 s were measured before and after cavity lining placement to determine the sealing ability and thermal insulating property, respectively. Data collected were subjected to statistical analysis. For paired data, paired t-test and Wilcoxon's signed rank test were used. One-way ANOVA was used for comparisons between multiple groups and the Mann-Whitney U test for comparisons between pairs. RESULTS: The mean difference in electrical resistance (in K ohm) of different cavity lining materials were as follows: group I = +3.53, group II = -1.00, group III = +20.43, and group IV = +11.44. The mean differences in the area (A D -A P ) under the time-temperature curve following heat application were as follows: group I = 6.6 mm 2 , group II = 15.3 mm 2 , group III = 130.5 mm 2 , and group IV = 412.0 mm 2 . The mean differences in the area (A D -A P ) under the time-temperature curve following cold application were as follows: group I = 24.5 mm 2 , group II = 3.2 mm 2 , group III = 314.9 mm 2 , and group IV = 480.5 mm 2 . CONCLUSION: Dentin bonding agent and RMGIC provided effective sealing of the dentinal tubules and significant thermal insulation when compared to the other tested cavity lining materials.