This study evaluated the microleakage of brackets bonded by four different enamel etching techniques. Forty freshly extracted human premolars were divided randomly into four equal groups and received ...the following treatment: group 1, acid etching; group 2, self-etching primer (SEP); group 3, erbium:yttrium–aluminum–garnet (Er:YAG) laser etching; and group 4, erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser etching. After photopolymerization, the teeth were kept in distilled water for 1 month and then subjected to 500 thermal cycles. Then, the specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and examined under a stereomicroscope. In addition, they were scored for marginal microleakage at the adhesive–enamel and bracket–adhesive interfaces from the incisal and gingival margins. Statistical analyses consisted of the Kruskal–Wallis test and the Mann–Whitney U test with Bonferroni correction. Microleakage occurred between the adhesive–enamel and bracket–adhesive interfaces in all groups. For the adhesive–enamel surface, a significant difference was observed between group 1 and groups 2 (
P
= 0.011), 3 (
P
= 0.002), and 4 (
P
= 0.000) on the gingival side. Overall, significant differences were observed between group 1 and groups 3 (
P
= 0.003) and 4 (
P
= 0.000). In dental bonding procedures, acid etching was found to result in the least microleakage. Since etching with a laser decreases the risk of caries and is time-saving, it may serve as an alternative to acid etching.
One of the most challenging issues following restoration is microleakage. The aim of this study was to investigate the effects of Er,Cr:YSGG laser with and without acid etching on microleakage of ...class V composite restorations. A total of 68 human intact premolars were selected, disinfected, and randomly allocated to four experimental groups (
n
= 16) as well as positive and negative controls (
n
= 2 each). Dimensionally, similar class V cavities were prepared on buccal surface of each tooth under the following conditions: group 1, bur cavity preparation and chemical etching (BE); group 2, bur cavity preparation and Er,Cr:YSGG laser conditioning (BLc); group 3, Er,Cr:YSGG laser cavity preparation and chemical etching (LE); and group 4, Er,Cr:YSGG laser cavity preparation and Er,Cr:YSGG laser conditioning (LLc). All samples were restored with composite. The teeth were sealed and immersed in 1 % methylene blue for 48 h before being sectioned. The microleakage evaluation was done under a stereomicroscope (×20). The leakage scores were recorded and Kruskal–Wallis and Mann–Whitney tests were used for statistical evaluations. The highest microleakage score was seen in gingival margins of group 4 (LLc) and the lowest in occlusal margins of group 3 (LE). The overall difference in leakage scores among the groups was statistically significant (
p
< 0.001) with gingival margins showing a significantly higher score than its occlusal counterparts (
p
< 0.001). It was noted that less microleakage could be achieved when cavities were prepared by laser compared to bur. In addition, less microleakage was seen in acid-etched cavities than laser-conditioned counterparts.
The aim of this in vitro study was to evaluate the effects of different types of adhesive systems on the microleakage of compomer restorations in Class V cavities prepared by erbium, chromium: ...yttrium scandium gallium garnet (Er,Cr:YSGG) laser. There were five test groups according to the type of adhesive applied to the cavities: Adper Single Bond 2 (Group 1), Scotchbond Multi-Purpose Plus (Group 2), Xeno III (Group 3), Clearfil Protect Bond (Group 4), Prime&Bond NT (Group 5). Dye penetration was evaluated under a stereomicroscope, and data were statistically analyzed by Kruskal-Wallis and Wilcoxon Signed Ranks tests. Gingival margins showed significantly higher microleakage than occlusal margins in all the test groups (p<0.05). Groups 1 and 2 showed significantly less microleakage than Group 5 (p<0.05), and there were no statistically significant differences among Groups 3, 4, and 5 (p>0.05). None of the dentin bonding agents eliminated microleakage completely, and higher microleakage scores were observed along the gingival margin than the occlusal margin.
This study aims to evaluate the composition, micro-structure and inorganic phase alternations of human dentine irradiated by Er,Cr:YSGG laser with water cooling spray system. X-ray diffraction (XRD) ...analysis indicated that the main inorganic phase of dentine before and after laser irradiation were all Hydroxyapatite (HA) structure, approximately 30 nm in size. No significant changes occurred in the average particle size after irradiation in four energy densities (6.18 J/cm2, 8.04 J/cm2, 9.89 J/cm2, 11.1 J/cm2). Atomic force microscope (AFM) phase image and the energy-dispersive spectroscope (EDS) analysis, however, demonstrated that the thermal effects of Er,Cr:YSGG laser with water-cooling spray system on the dentin surface was intense enough to induce notable decrease of the organic matter. Both scanning electron microscopy (SEM) and AFM analysis showed that the irradiated dentine presented rough surface morphology. The surface is clean and dentinal tubules are completely open. The ablation rate of both peri- and intertubular dentine increased at higher energy densities but no significant changes of gross appearance took place. Chemical analysis reveals that laser photothermal effect would decrease significantly the organic content of superficial dentinal layer. We conclude that the Er,Cr:YSGG laser, as a new type clinic laser, would not significantly influence the inorganic phase structure of the surface dentine layer, however, thermal ablation was occurred in organic component. Moreover, the rough ablated surface as well as the opened dentinal tubules induced by irradiation, might be advantageous to the infiltration of the adhesive materials, thus the adhesion of dental restoration could be enhanced. Further studies should focus on the correlation between bond strength and Er,Cr:YSGG lased dentine.
Background: Evaluation of microleakage is important for assessing the success of new methods for surface preparation and new adhesive restorative materials. The aim of this laboratory study was to ...assess microleakage at the margins of composite restorations in Er,Cr:YSGG laser prepared cavities on the cervical aspects of teeth by means of dye penetration, and compare this with conventionally prepared and conditioned cavities.
Methods: Class V cavities were produced on sound extracted human teeth, which had been assigned randomly to one of three groups (N = 10 each), as follows: Group 1 – prepared using a diamond cylindrical bur and then treated with 37% phosphoric acid; Group 2 – irradiated with an Er,Cr:YSGG laser (Biolase Waterlase) and then treated with 37% phosphoric acid; Group 3 – irradiated only with the laser. After application of bonding agent (Excite, Ivoclar Vivadent), all cavities were restored with composite resin (Heliomolar). After polishing the restorations, the teeth were thermocycled from 5–50°C for 500 cycles. Dye leakage was assessed after immersion in methylene blue, by examining longitudinal sections in a stereomicroscope at ×30 magnification.
Results: The extent of dye penetration was lowest in the laser only group (Group 3). Penetration of dye to dentine and axial walls occurred in 80 per cent of conventionally prepared (bur + acid) specimens, but in the laser group, dye penetration to the axial wall occurred in only 30 per cent of cases. There was a strong statistical association between treatment group and the distribution of microleakage scores (Chi‐square, P = 0.0023).
Conclusions: For Class V cavities, with the adhesive materials employed, higher microleakage occurs with phosphoric acid etching of bur‐ or laser‐cut surfaces, than with the surface created by use of the laser alone without additional conditioning.
This study investigates the healing process that takes place in the bone and soft tissue of the maxilla and the mandible after perforation by an Er,Cr:YSGG laser device. The jaws of New Zealand white ...rabbits were irradiated with an Er,Cr:YSGG laser, forming wounds 0.4 mm in diameter. Irradiation parameters were as follows: repetition rate was 20 pulse/s, pulse duration was 140-200 micros, power was 2 W, exposure time was 10 s, energy density was 80 J/cm(2). After sacrifice at 0-56 days post-surgery, gross observations and histological examinations were performed. Effective hemostasis was achieved after Er,Cr:YSGG laser surgery. There was a minimal delay before the healing began. After 56 days all of the bone defects had been completely replaced by new bone. In conclusion, the Er,Cr:YSGG laser allows precise surgical ablation with minimal thermal damage to adjacent tissues in vivo. The overall subsequent healing was favorable. This laser may potentially be used in minor oral surgery.
The authors conducted an in vitro study to evaluate the shear bond strength of a fissure sealant to enamel pretreated with erbium,chromium:yttrium, scandium,gallium,garnet (Er,Cr:YSGG) laser or air ...abrasion followed by acid etching.
The authors sectioned extracted sound premolars mesiodistally and used the buccal and lingual surfaces for experimental analysis. They divided specimens randomly into three groups of 15 each according to the enamel surface pretreatment methods: group A, 37 percent phosphoric acid; group B, air abrasion followed by acid etching with 37 percent phosphoric acid; group C, irradiation with Er,Cr:YSGG laser followed by acid etching with 37 percent phosphoric acid. After applying a bonding system, the authors bonded cylinders of sealant to the enamel surfaces by using transparent gelatin tubes (0.7 millimeter in diameter and 1 mm in height) and then polymerized them. They stored all specimens in distilled water at 37 degrees C for 24 hours. They tested shear bond strength by using a universal testing machine with a crosshead speed of 0.5 mm per second. The authors analyzed the data by means of one-way analysis of variance and Tukey-Kramer post hoc tests (alpha = .05).
The bond strength of group B specimens was statistically higher than those of group A and group C specimens (P < .05). The authors found no statistically significant differences in shear bond strength between surfaces treated with Er,Cr:YSGG laser and those treated with acid etching alone (P > .05).
Pretreatment of enamel surfaces with air abrasion increased the bond strength of fissure sealant, but pretreatment with Er,Cr:YSGG laser did not increase the effectiveness of conventional acid etching of enamel in sealant bonds.
summary In the present study, the compositional changes and knoop hardness of the cavity floor prepared by Er,Cr:YSGG laser irradiation was compared with that of the conventional bur cavity. Fifteen ...laser and 15 bur cavities were cross‐sectioned, and subjected to atomic analysis by SEM‐EDX and knoop hardness test. Statistical analyses were performed using the Mann–Whitney U‐test; a value of P < 0·01 was considered significant. Surface characteristics of the prepared cavities were also investigated by light microscopy and scanning electron microscopy (SEM). The results showed that the quantities of Ca (Ca weight %) and P (P weight %) were increased significantly in the laser cavity floor but no significant differences were found between the Ca/P ratio and knoop hardness number of laser and bur cavities. The SEM observation revealed that the lased cavity surface was irregular and there was also the absence of a smear layer; the orifice of dentinal tubules was exposed. Er,Cr:YSGG laser device is considered as one of the most effective and safe devices for cavity preparation because of its many advantages. This includes easy delivery system, minimal thermal damage to the surrounding tissues, minimal thermal‐induced changes of dental hard tissue compositions, and favourable surface characteristic.
The aim of this in vitro study was to analyze hybrid layer and nanoleakage of composite resin restorations in cavities prepared by either Er,Cr:YSGG laser or bur, followed by acid etching in primary ...teeth. Ten extracted primary molar teeth were randomly allocated into two groups consisting of ten cavities according to surface treatment regimen: Er,Cr:YSGG laser + acid etching(group 1) and bur + acid etching(group 2). Restorations of all samples were completed. Then, teeth were sectioned and immersed to ammoniacal silver nitrate solution. After polishing, hybrid layer thicknesses were examined under scanning electron microscopy (SEM) and ion analysis was carried out with SEM/energy dispersive X-ray spectroscopy preparation in terms of nanoleakage. Hybrid layer thickness and the amount of silver ions were assessed for the acid-etched groups. The collected data were analyzed with independent sample
t
test and Spearman’s rank correlation. In groups 1 and 2, the mean hybrid layer thicknesses were 4.25 ± 1.41 and 5.24 ± 1.07 μm and the silver ion percentages were 10.97 ± 13.81 and 22.79 ± 21.62 %, respectively. Although no significant correlation was observed between the increase of hybrid layer thickness and the amount of silver ions, more silver ions were observed in group 2 (
p
< 0.05). According to the results of this study, acid-etched cavities prepared with laser promoted better results when compared to the acid-etched cavities prepared with bur.
Aim
This study was designed to compare the bond strength of composite resin restorations on the buccal surface of primary human canine after conditioning by conventional acid etching and Er,Cr:YSGG ...laser.
Methods
Twenty sound primary canines were cut buccolingually into two halves and each half was randomly placed in Er,Cr:YSGG laser or acid etch group. The samples in the acid etch group were etched with 37 % phosphoric acid for 30 s. The samples in the laser group were prepared by Er,Cr:YSGG laser. The G6-Tips and 600 µm diameter were used with a 1.5 W of power output, pulse duration of 140 µs and repetition rate of 20 Hz. The bonding agent was applied on the buccal surface of each sample and layers of resin composite were placed. The samples’ bond strengths were evaluated by a microtensile test instrument.
Results
The mean of microtensile bond strength was 18.55 ± 6.41 in the laser group and 24.62 ± 5.56 in acid etch group. Microtensile bond strength achieved by laser conditioning was significantly lower than microtensile bond strength achieved by the conventional acid etching.
Statistics
To compare the results between the acid etch and laser group, the paired
t
test was performed (
p
value < 0.001).
Conclusion
Conditioning enamel in primary teeth by Er,Cr:YSGG laser, cannot be used as an alternative method for acid etching and cannot substitute this conventional method.
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