Effect of a CO2 Laser on the Inhibition of Root Surface Caries Adjacent to Restorations of Glass Ionomer Cement or Composite Resin: An In Vitro Study.

This study investigated the effect of CO2 laser irradiation on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement (GIC) or composite resin (CR) restorations. 40 dental blocks were divided into 4 groups: G1 (negative control): cavity preparation + adhesive restoration with CR; G2: (positive control) cavity preparation + GIC restoration; G3: equal to group 1 + CO2 laser with 6 J/cm(2); G4: equal to group 2 + CO2 laser. The blocks were submitted to thermal and pH cycling. Dental demineralization around restorations was quantified using microhardness analyses and Light-Induced Fluorescence (QLF). The groups showed no significant differences in mineral loss at depths between 20 µm and 40 µm. At 60 µm, G2 and G3 ≠ G1, but G4 = G1, G2 and G3. At 80 µm, G4 ≠ G1, and at 100 µm, G4 = G2 = G1. At 140 and 220 µm, G2, G3, and G4 = G1. The averages obtained using QFL in groups 1, 2, 3, and 4 were 0.637, 0.162, 0.095, and 0.048, respectively. QLF and microhardness analyses showed that CO2 laser irradiation reduced mineral loss around the CR restorations but that it did not increase the anticariogenic effect of GIC restorations.

Effect of enamel preparation method on in vitro marginal microleakage of a flowable composite used as pit and fissure sealant.

OBJECTIVES: The aim of this in vitro study was to evaluate the microleakage in occlusal surfaces, after preparation with Er:YAG laser and compared to the diamond-bur conventional technique. METHODS: Thirty premolars were divided into three groups: I - high-speed handpiece + 37% phosphoric acid; II - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + 37% phosphoric acid; and III - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + Er:YAG laser (80 mJ, 4 Hz, and 25 mJ/cm(2)). All cavities received the same adhesive system and were restored with flowable composite according to manufacturer's instructions. Teeth were submitted to thermal cycling and immersed in 50% silver nitrate solutions for 8 h in total darkness. Specimens were sectioned longitudinally in the bucco-lingual direction, in slices of 1 mm thick. Each slice was immersed into photo developing solution and was photographed, and microleakage was scored from 0 to 7, by three calibrated examiners. RESULTS: A statistically significant difference (P < 0.0001) was observed between Er:YAG laser prepared and etched specimens and those in the other groups. CONCLUSIONS: It can be concluded that no significant difference was noted between the two types of enamel preparation when etching was performed. Preparing and treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.

Validity and reproducibility of different combinations of methods for occlusal caries detection: an in vitro comparison.

This study assessed the validity and reproducibility of different combinations of occlusal caries detection methods: visual examination (VE), laser fluorescence (LF) and radiographic examination (RE). Intra- and interexaminer reproducibilities were also assessed. Forty-seven extracted human molars were used and 121 sites, either suspected or not to be carious, were chosen. Occlusal surfaces were examined by 8 volunteers, assigned to three groups according to their level of knowledge and clinical experience on dental practice: group I, undergraduate students; group II, postgraduate students; group III, professors. Three combinations of methods were tested: A: VE+LF, B: VE+RE, C: VE+LF+RE. The examiners scored the sites using ranking scales and chose a final score based on their clinical experience. The gold standard was determined by histological examination of the sites. In general, LF and RE yielded poorer results than the combinations of methods. For combination A, group III showed the highest sensitivity, while group II showed the highest specificity. For combination B, group II showed moderate sensitivity whereas groups I and III exhibited low sensitivities; all groups of examiners reached substantial specificity. For combination C, all groups exhibited moderate sensitivity and substantial specificity. Interexaminer reproducibility ranged from fair to moderate for combinations A and C, while for combination B kappa values indicated moderate interexaminer reproducibility. It may be concluded that individual exams presented inferior performance than the conjunction of them. Combination C (VE+LF+RE) resulted in the best accuracy for all groups. The knowledge background of the examiners influenced their ability to detect caries lesions and affected interexaminer reproducibility.