Silmara Aparecida Milori Corona

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.

Microleakage of a resin sealant after acid-etching, Er:YAG laser irradiation and air-abrasion of pits and fissures.

OBJECTIVE The aim of this in vitro study was to assess microleakage underneath a filled pit-and-fissure sealant bonded to occlusal surfaces treated by four enamel etching techniques. SUMMARY BACKGROUND DATA There has been no report of a study assessing microleakage of a pit-and-fissure sealant, comparing acid-etching, Er:YAG laser and air-abrasion for treating enamel surface. METHODS Forty extracted human third molars were selected and randomly assigned into four groups of ten teeth: group I, the occlusal surfaces were acid-etched; group II, a very short pulsed Er:YAG laser was used to treat the surfaces; group III, aluminum oxide air-abrasion was associated with acid-etching; group IV, Er:YAG laser was associated with acid-conditioning. The surfaces were sealed and the teeth were stored for 7 days in distilled water. Then, specimens were thermocycled, immersed in a 0.2% rhodamine solution, sectioned, and analyzed for leakage using an optical microscope connected to a video camera. The images were digitized and analyzed by software that allowed microleakage assessment in millimeters. RESULTS Statistical analysis showed that occlusal surfaces treated exclusively by the Er:YAG laser (group II) provided the poorest marginal sealing and that acid-etching (group I) was statistically similar to aluminum oxide air-abrasion + acid etching (group III) and to Er:YAG laser + acid-etching (group IV). CONCLUSIONS The results suggest that complementing either air-abrasion or Er:YAG laser irradiation with a subsequent acid-conditioning did not lessen microleakage at the enamel-sealant interface when compared with an acid-etched group. It was also observed that treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.

Assessing Microleakage on Class V Composite Resin Restorations after Er:YAG Laser Preparation Varying the Adhesive Systems

OBJECTIVE The aim of this study was to assess the performance of three bonding agents in preventing microleakage of class V cavities prepared and treated by Er:YAG laser associating with acid etching. BACKGROUND DATA There has been very little research comparing the efficiency of single-component and self-etching adhesive systems in preventing microleakage of cavities prepared and conditioned with Er:YAG laser. MATERIALS AND METHODS Thirty cavities - with occlusal margin in enamel and cervical in dentin/cementum - were prepared in sound human third molars using a short pulsed Er:YAG laser (500 mJ/5 Hz) The enamel and dentin surfaces were conditioned for 30 sec using lower dosimetries (120 mJ/4 Hz), and the samples were randomly assigned into three groups, according to the adhesive system: (I) Bond-1; (II) Prime & Bond NT; and (III) Etch & Prime 3.0. Groups I and II were acid-etched for 15 sec, and group III did not receive any acid treatment once a self-etching system was employed. Cavities were restored with a light-cured composite resin (JEK-Z250 Filtek-250), and after finishing, the samples were thermocycled, isolated with epoxy resin and nail varnish, immersed in a 0.2% Rhodamine B solution for 24 h, and sectioned longitudinally. The sections obtained were analyzed for leakage using an optical microscope connected to a computer and a video camera. We digitized the images using a special software program that allowed a quantitative evaluation of microleakage in millimeters. RESULTS Statistical analysis using the Kruskal-Wallis test showed statistically significant difference between both margins, and the occlusal region presented better marginal sealing. Comparing the three resin bonding systems, Prime & Bond NT entirely sealed both margins, while Etch & Prime 3.0 provided the poorest overall results, showing a statistically significant difference (p < 0.01). CONCLUSION It may be concluded that, for all the tested materials, microleakage values were higher in cervical (dentin/cementum) margins. Additionally, Prime & Bond NT provided a complete elimination of marginal infiltration at both margins, after treating the dental surface with laser irradiation associated with a sequent acid-etching.

Water flow on erbium:yttrium-aluminum-garnet laser irradiation: effects on dental tissues

Since lasers were introduced in dentistry, there has been considerable advancement in technology. Several wavelengths have been investigated as substitutes for high-speed air turbine. Owing to its high absorbability in water and hydroxyapatite, the erbium:yttrium–aluminum–garnet (Er:YAG) laser has been of great interest among dental practitioners and scientists. In spite of its great potential for hard tissue ablation, Er:YAG laser effectiveness and safety is directly related to an adequate setting of the working patterns. It is assumed that the ablation rate is influenced by certain conditions, such as water content of the target tissue, and laser parameters. It has been shown that Er:YAG irradiation with water coolant attenuates temperature rise and, hence, minimizes the risk of thermally induced pulp injury. It also increases ablation efficiency and enhances adhesion to the lased dental tissue. The aim of this review was to obtain insights into the ablation process and to discuss the effects of water flow on dental tissue ablation using Er:YAG laser.

Viability of using enamel and dentin from bovine origin as a substitute for human counterparts in an intraoral erosion model

This study ascertained whether under dental erosion models that closely mimics the real-life situation enamel and root dentin from bovine origin would be reliable substitutes for human counterparts. Through a 2x2 crossover design, in a first trial, 14 volunteers wore a palatal device containing slabs of bovine and human enamel. Half of the participants ingested (4x daily, for 10 days) orange juice first, crossing over to mineral water, while the remainder received the reverse sequence. In a second trial, volunteers wore devices with slabs of bovine and human root dentin. Except for the duration of each intraoral phase, which lasted 2 rather 10 days, the experiment with root dentin run exactly as for enamel. Dental substrates were analyzed for surface microhardness. Two-way ANOVAs (α=0.05) indicated no difference between the microhardness values recorded for human and bovine enamel (p=0.1350), but bovine root dentin had lower microhardness compared to its human counterpart (p=0.0432). While bovine enamel can reliably substitute its human counterpart in in situ dental erosion models, bovine root dentin does not seem to be a viable alternative to the corresponding human tissue.

Tensile Bond Strength of Dentin-Resinous System Interfaces Conditioned with Er:YAG Laser Irradiation

OBJECTIVE The aim of this in vitro study was to assess tensile bond strength of dentin-resinous system interfaces conditioned with Er:YAG laser irradiation. BACKGROUND DATA There are different results reported in the literature which relate to laser Er:YAG effects on dentin surface as a pretreatment during adhesives procedures. MATERIALS AND METHODS Forty-two surfaces of human dentin from third upper molar were used after being extracted and kept in the refrigerator in 0.5% chloramines aqueous solution and then divided into three experimental groups and three control groups. The chosen restorative systems were Alert (Jeneric/Penton), Prodigy (Kerr Co.), and Z-100 (3M Co.), with correspondent dental adhesives Bond 1, Optibond Solo, and Single Bond, respectively. To conduct tensile tests, a special system of pairs of rods aligned in a specific apparatus was used, in accordance with ISO/TR 11405 standard (1994). RESULTS By means of statistical analysis, the Kruskal Wallis test, it was noticed that group IE (laser + acid + Alert), 18.89 MPa, differed considerably from group IC (acid + Alert), 8.03 MPa (p < 0.10), but did not differ from the other groups. Group IIC (acid + Prodigy), 19.88 MPa, differed from group IIE (laser + acid + Prodigy), 12.57 MPa (p < 0.05), but did not differ from groups IIIE (laser + acid + Z-100), 14.11 MPa, and IIIC (acid + Z-100), 19.58 MPa. Group IIIE did not differ statistically from group IIIC. CONCLUSION It was concluded that previous Er:YAG laser treatment on the dentinal structure only improved the tensile bond resistance of the Alert restorative system.

Influence of the Frequency of Er:YAG Laser on the Bond Strength of Dental Enamel

OBJECTIVE The present study had the aim of evaluating the influence of different frequencies of the Er:YAG laser on adhesive resistance of enamel and one restorative system. BACKGROUND DATA There have been no reports of studies assessing the influence of the pulse frequency variation of the Er:YAG laser on adhesive resistance of the enamel/resin interface. MATERIALS AND METHODS Fifty surfaces of enamel from extracted human third molars were planed and divided into five groups at random. Enamel surface treatment was realized by the Er:YAG laser at 80-mJ power and 1-, 2-, 3-, and 4-Hz pulse frequencies, followed by etching. For the control group, only acid conditioning with 37% phosphoric acid for 15 sec was used. The Single Bond/Filtek Z250 system was chosen for the fabrication of the specimens, which were stored in 100% relative humidity for 24 h, at 37 degrees C. The specimens were submitted to tensile resistance tests using a Universal Testing Machine (50 Kgf and 0.5 mm/min). RESULTS The mean values in MPa were 1 Hz, 25.58 (+/-6.16); 2 Hz, 25.58 (+/-3.79); 3 Hz, 21.34 (+/-3.78); 4 Hz, 21.17 (+/-3.13); and phosphoric acid only, 22.44 (+/-7.0). Data were submitted to statistical analysis using ANOVA, and there was no significant difference in tensile resistance between the studied groups. CONCLUSION The results suggest that the Er:YAG laser, with 80-mJ power associated with acid conditioning at 1-, 2-, 3-, and 4-Hz frequencies, did not present significant improvement in tensile bonding of enamel, as compared to acid conditioning only.

Influence of sodium hypochlorite and edta on the microtensile bond strength of a self-etching adhesive system

Chemical substances used during biomechanical preparation of root canals can alter the composition of dentin surface and affect the interaction with restorative materials. Objective The purpose of this study was to evaluate the microtensile bond strength (µTBS) of a self-etching adhesive system to dentin irrigated with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (eDTA). Material and Methods Thirty human third molars were sectioned 3 mm below the occlusal surface, polished with 600- to 1200-grit silicon carbide papers, and randomly divided into 3 groups: G1 (control): no irrigating solution; G2: 1% NaOCl; and G3: 1% NaOCl followed by the application of 17% eDTA. The specimens received the self-etching adhesive system (XeNO III - Dentsply), restored with microhybrid composite resin (Z250 - 3M ESPE), sectioned and trimmed to create 4 hourglass-shaped slabs of each tooth. The slabs were tested in microtensile strength in a universal testing machine (emic DL 2000) at a crosshead speed of 0.5 mm/min until fracture. The results were analyzed statistically by ANOVA and Newman-Keuls test. Results Mean µTBS values and standard deviations in MPa were: G1 = 11.89 ± 4.22; G2 = 19.41 ± 5.32; G3 = 11.34 ± 4.73. 1% NaOCl increased the adhesive resistance significantly (p<0.001/ F=22.5763). The application of 1% NaOCl/17% eDTA resulted in statistically similar µTBS to the control group. Conclusions None of the irrigants affected negatively the µTBS of XeNO III to dentin. The use of 1% NaOCl alone resulted in higher bond strength than the other treatments. The combination of 1% NaOCl and 17% eDTA produced similar bond strength to that of untreated dentin.

Microhardness and SEM after CO2 laser irradiation or fluoride treatment in human and bovine enamel

Background: It remains uncertain as to whether or not CO2 laser is able to hinder demineralization of enamel. The possibility to use bovine instead of human teeth on anticariogenic studies with laser has not yet been determined. Purpose: To compare the ability of CO2 laser and fluoride to inhibit caries‐like lesions in human enamel and to test whether a similar pattern of response would hold for bovine enamel. Study Design: Ninety‐six enamel slabs (2 × 2 × 4 mm) (48 from bovine and 48 from human teeth) were randomly distributed according to surface treatment (n = 12): CO2 laser, 5% sodium fluoride varnish (FV), 1.23% acidulated phosphate fluoride (APF) gel, or no treatment (control). Specimens were subjected to a 14‐day in vitro cariogenic challenge. Microhardness (SMH) was measured at 30 μm from the surface. For ultrastructural analysis, additional 20 slabs of each substrate (n = 5) received the same treatment described earlier and were analyzed by SEM. Results: ANOVA and Tukey test ascertained that CO2 laser promoted the least mineral loss (SMH = 252a). Treatment with FV resulted in the second highest values (207b), which was followed by APF (172c). Untreated specimens performed the worst (154d). SEM showed no qualitative difference between human and bovine teeth. APF and control groups exhibited surfaces covered by the smear layer. A granulate precipitate were verified on FV group and fusion of enamel crystals were observed on lased‐specimens. Conclusions: CO2 laser may control caries progression more efficiently than fluoride sources and bovine teeth may be a suitable substitute for human teeth in studies of this nature. Microsc. Res. Tech. 73:1030–1035, 2010.

Influence of cavity preparation with Er:YAG Laser on enamel adjacent to restorations submitted to cariogenic challenge in situ: A polarized light microscopic analysis

Er:YAG laser has been used for caries removal and cavity preparation, using ablative parameters. Its effect on the margins of restorations submitted to cariogenic challenge has not yet been sufficiently investigated. The aim of this study was to assess the enamel adjacent to restored Er:YAG laser‐prepared cavities submitted to cariogenic challenge in situ, under polarized light microscopy.