Comparative cutting effectiveness of an ultrasonic diamond tip and a high-speed diamond bur.

AIM: The aim of this in vitro study was to compare an ultrasonic diamond tip to a high-speed conventional diamond bur regarding the cutting effectiveness in enamel and dentin of human teeth. METHODS: Twenty permanent molars were longitudinally sectioned in the buccal-lingual plane giving 40 specimens, 20 for enamel and 20 for dentin groups. One cavity was performed in each specimen using a spherical diamond tip (83231, CVDentus(R), CVDVale, São José dos Campos, SP, Brazil) coupled with an ultrasound device or a conventional spherical diamond bur (1013, KG Sorensen, São Paulo, Brazil)) coupled with a high-speed turbine. A modified measurement analysis using the Radiocef 4.0 software (Radiocef Memory) was applied to determine the width and the depth of the cavities on scanning electron microscopy (SEM) at x50 magnification micrographs. The features of the cavities and the characteristics of the cutting instruments were also examined under different magnifications by SEM. RESULTS: Statistical analysis by Kruskal-Wallis non-parametric and Dunn post hoc tests (P < or = 0.05) showed that cavities prepared in enamel and dentin with the ultrasonic diamond tip were shallower and narrower than those prepared with conventional diamond bur. The internal walls of cavities prepared in dentin by the ultrasonic diamond tip reproduced the superficial aspect of the diamond, however, scratches were observed in the internal walls of the dentin cut by high-speed conventional diamond bur. CONCLUSIONS: Both instruments were effective in enamel and dentin cutting; however, cavities prepared with a high-speed conventional diamond bur showed more invasive characteristics.

Evaluation of the microtensile bond strength of composite resin restoration in dentin prepared with different sizes of aluminum oxide particles, using the air abrasion system.

AIM: The purpose of this in vitro study was to evaluate the influence of the abrasive technique on the microtensile bond strength of composite resin restorations. In addition, any differences in the microtensile bond strength were observed when different aluminum oxide particle sizes were used. METHODS: Flat coronal dentin surfaces were randomly distributed into 3 groups, according to surface treatment: Group A27 Air-abraded dentin with 27 microm aluminum oxide particles; Group A50-Air-abraded dentin with 50 microm aluminum oxide particles; Group HS cut dentin with a #1013 diamond bur in high-speed rotary instrument. After the bonding procedure (Single Bond/Z100), the teeth were stored in distilled water at 37 masculineC for 48 h prior to sectioning. Then, each bonded tooth was longitudinally sectioned producing sticks with a cross-sectional area of 0.81 mm2. The tensile load was applied at a crosshead speed of 0.5 mm/min, until the stick fractured. The data were analyzed by one-way ANOVA and post hoc multiple comparisons using Tukey's test. RESULTS: No difference was observed in composite bond strength when 27 and 50 microm aluminum oxide particles were used for dentin surface preparation using an air abrasion system. However, air-abraded dentin, using 27 microm aluminum oxide particles, demonstrated a higher bond strength when compared to dentin prepared by the conventional method (bur in high-speed). CONCLUSIONS: The air-abraded dentin, using 27 microm alumina powder, demonstrated higher composite bond strength when compared to bur-cut dentin, raising the possibility that this method may increase restoration longevity.

Restoration of severely decayed primary incisors using indirect composite resin restoration technique.

Caries of primary incisors is a common problem in paediatric dentistry in some countries. The restoration of primary incisors which have been severely damaged by early childhood caries or trauma is also a difficult challenge for clinicians. This case report describes an indirect technique for the restoration of primary anterior teeth using composite resin reinforced with a fibre-glass post. Over a one-year period, the crowns have demonstrated good retention and aesthetic results. The restorations were provided in two short chair-side sections, with satisfactory patient cooperation.

In vitro evaluation of probiotics microorganisms adhesion to an artificial caries model.

OBJECTIVE: This in vitro study compared the adhesion of two probiotics microorganisms (Lactobacillus casei Shirota and Lactobacillus acidophilus) to an artificial caries model. METHOD: In total, 30 bovine teeth were longitudinally sectioned, excluding the lingual half surface. The specimens were covered with nail varnish, except for an area of 3 by 5 mm in dentin, suspended in an artificial caries solution promoted by Streptococcus mutans, and incubated at 37 degrees C. After 14 days, the specimens were separated equally into two groups and transferred to a brain heart infusion culture media containing L. acidophilus (group A) and L. casei Shirota (group S), at 37 degrees C. After 48 h, the exposed area of dentin was washed with 1 ml of distilled water and the caries dentin was removed and dispersed in 1 ml of saline solution. The samples of distilled water and caries dentin were diluted and inoculated in Rogosa selective Lactobacillus agar. The results in CFU/ml were analysed by the Mann-Whitney test. RESULTS: There was no significant difference between Groups A and S for the lactobacilli count in samples of distilled water (P = 0.237). CONCLUSIONS: The amount of L. acidophilus in the artificially caries dentin was significantly superior compared to L. casei Shirota (P = 0.047), suggesting an inferior adhesion potential for this microorganism.