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

The purpose of this study was to evaluate and compare the sealing ability and the thermal insulating capability of four different cavity lining materials.

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.

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 .

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.