Removal of organic debris with Er:YAG laser irradiation and microleakage of fissures sealants in vitro.

The current study was conducted to improve fissure sealing by pre-treatment with Er:YAG laser irradiation in order to remove organic debris. The surface morphology, surface roughness of fissure cavities, and the degree of microleakage after laser treatment were compared with those after bristle brush treatment in vitro. Sixty extracted human teeth were used in this study. The teeth were randomly divided into two groups of 30 each. Artificial fissures were prepared in all teeth into which artificial organic debris was placed. The debris in 30 teeth of one group was removed by means of Er:YAG laser system and the remaining 30 teeth were cleaned using a bristle brush with prophylaxis paste. Surface morphology and surface roughness of were analyzed in ten samples from each group by color laser three-dimensional (3D) microscopy and by scanning electron microscopic examination. The remaining samples were then filled with sealant and subjected to a microleakage test under thermocycling. Statistical analysis was performed using the Mann-Whitney U test; a value of p < 0.05 was considered significant. Morphologically, most of the debris was removed by Er:YAG laser treatment, whereas some fissures were not cleaned by bristle brush. However, microleakage test of both laser and etched brush methods showed similar results. Laser technique might facilitate good adaptation of resin sealant to enamel, because of an increase in surface roughness and favorable surface characteristics.

Effects of mineral trioxide aggregate on the differentiation of rat dental pulp cells.

The effect of mineral trioxide aggregate (MTA) on the odontoblast-like differentiation of pulp cells was evaluated using heat-shock protein 25 (hsp25) as a marker for odontoblast differentiation. The cells were cultured with tooth-colored MTA or calcium hydroxide-containing cement (Dycal). The effects of the materials on the pulp cells were observed using a confocal laser scanning microscope. The cells were labelled immunocytochemically using polyclonal antibodies against hsp25 and actin. The mRNA expression of hsp25 and dspp in the pulp cells at 2 days were examined by quantitative reverse transcription-polymerase chain reaction (RT-PCR). Most of the cells cultured with MTA showed an intense immunolabelling for hsp25 and the mRNA expressions of hsp25 and dspp at 2 days were higher than those cultured with Dycal. These findings indicate that MTA is an effective pulp capping material and is able to induce the differentiation of odontoblast-like cells and the formation of reparative tertiary dentin with minimum apoptosis.