This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or ...sandblasting.
Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores.
The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent.
According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice.
The aim of the present study was to investigate in vitro the effect of Er:YAG laser on bonding to enamel, varying the irradiation distance.
Tensile bond strength of an adhesive restorative system to ...non-irradiated and irradiated enamel surfaces was evaluated. Thirty caries-free human third molars were sectioned in mesio-distal direction and embedded in acrylic resin. Enamel was flattened, and a 3-mm-diameter bonding area was demarcated. Specimens were randomly assigned into six groups: groups I–V were treated with the Er:YAG laser (80
mJ/2
Hz), varying the irradiation distance (11, 12
mm-focused, 14, 16 and 17
mm, respectively), followed by 35% phosphoric acid etching. Control group (VI) received treatment with phosphoric acid alone. Single Bond adhesive system was applied on the conditioned enamel, and composite resin cones, bonded to enamel, were fabricated with Z250. After storage, samples were tested in tensile to failure (50
kgf and 0.5
mm/min).
Means in MPa were: I-9.67 (±3.44); II-13.29 (±2.65); III-13.33 (±2.22); IV-14.87 (±3.58); V-16.43 (±4.52); VI-22.90 (±3.03). ANOVA and Tukey test revealed statistically significant decrease of bond strength in group I (
P<0.05). Groups II–IV presented similar results, as did groups IV and V. Control group (VI) yielded the best overall performance (
P<0.05).
Er:YAG laser irradiation adversely affected adhesion to enamel. However, bond strength was influenced by the irradiation distance, thus being stronger with the increase of distance to the target tissue.
Erosion is an important cause of tooth mineral loss. The combined use of lasers and fluoride has been introduced as a novel modality for the prevention of enamel demineralization. This study aimed to ...assess the effect of Er:YAG laser combined with fluoride application on primary and permanent enamel resistance to erosion.
Eighty enamel specimens of permanent (n=40) and primary (n=40) molars were prepared and randomly assigned to 4 groups: C-control (no pretreatment), F-acidulated phosphate fluoride (APF) gel, FL-APF gel application followed by Er:YAG laser irradiation, and LF-Er:YAG laser irradiation followed by the application of APF gel . The specimens were then submitted to pH cycling using Coca-Cola (pH=2.4). Enamel micro-hardness was measured using the Vickers microhardness tester before pretreatment and after the erosive process. The collected data were analyzed using the Kolmogorov-Smirnov test, two-way ANOVA and repeated measures ANOVA.
The micro-hardness of both permanent and primary enamel specimens significantly decreased after the erosive process (
< 0.05). In the permanent enamel specimens, the greatest reduction in micro-hardness was noted in groups C and F, while the least reduction was noted in group FL. However, these differences were not statistically significant (
> 0.05). In the primary enamel specimens, the greatest reduction in micro-hardness was noted in groups C and LF, while the least reduction was noted in group F. These differences were not statistically significant (
> 0.05).
Within the limitations of this study, Er:YAG laser irradiation combined with fluoride application could not prevent erosion in permanent and primary enamel during the erosive process.
Objective To evaluate the therapeutic effects of erbium ⁃ doped: yttrium aluminium garnet laser (Er: YAG laser) combined with guided bone regeneration (GBR) in the treatment of peri ⁃implantitis bone ...defect. Methods A total of 26 implants in 15 patients with peri ⁃implantitis were selected and divided into experimental group (14 im⁃ plants) and control group (12 implants) randomly. The experimental group was treated with Er: YAG laser combined with GBR, and the control group was treated with mechanical curettage with GBR. Clinical periodontal index test includ⁃ ing plaque index (PI), sulcus bleeding index (SBI), probing depth (PD) and clinical attachment level (CAL) were checked at baseline, 3 months and 6 months. All the above data were statistically analyzed. Results All of the clinical periodontal index were improved after surgery. SBI, PD and CAL of the experimental group was 0.8 ± 0.2 mm, 5.8 ± 0.8 mm, and 2.3 ± 0.7 mm, while they were 1.1 ± 0.2 mm, 6.2 ± 0.6 mm, and 3.6 ± 0.6 mm in the control group. Th
In view of the advantages of 1.6‐μm laser, it has important applications in the fields of laser radar, industry, military, and optical communication. This paper mainly focuses on 1.6‐μm Er: YAG ...solid‐state‐laser for Laser Radar. The references about pulsed 1.6‐μm single‐longitudinal‐mode laser, continuous wave 1.6‐μm Er: YAG single‐longitudinal‐mode seed laser, and pulsed 1.6‐μm Er: YAG Q‐switched amplifier are collected and analyzed. The development status is introduced, the main problems are identified, and the future development direction is clarified. Maybe, this can provide a reference for other scholars.
Purpose: Er: YAG laser is often used for dental treatment as it has been shown to be excellent for preparing the hard tissues of teeth. However, it has been reported that the bond strength of ...composite restorations is adversely affected in dentin irradiated by Er: YAG laser compared with non-irradiated dentin. The denatured layer formed on the laser irradiated dentin surface is considered to be the cause. In this study, we examined the effect of pre-conditioning methods with clinical instruments for removing the denatured layer formed on the irradiated dentin surface, on the bond strength of composite resin for laser irradiated dentin. Methods: A dentin flat surface was formed on the labial side of extracted bovine lower incisors. The specimens were divided into seven groups according to the type of surface treatment given 1) non-irradiation (Control), 2) laser irradiation of 100 mJ, 10 pps (LI), 3) laser irradiation and etching with phosphoric acid (PA), 4) laser irradiation and cutting with a steel burr (RB), 5) laser irradiation and cutting with a spoon excavator (SE), 6) laser irradiation and air abrasion (AA), and 7) laser irradiation and cutting with a smart burr (SB) (n=5). An adhesive system (Clearfil Mega Bond) was applied after each pre-conditioning method following the manufacturer’s instructions. The tensile bond strengths (TBSs) were measured and data were evaluated for statistical analysis by the one-way layout ANOVA and Scheffé’s test (p<0.05). Results: The TBSs of the RB and AA groups were lower than those of the Control group, but no significant difference was found. The TBSs of the LI, PA, SE and SB groups were significantly lower than those of the LI group. The TBSs of the RB group were significantly higher than those of the LI, SE and SB groups. Conclusion: We found that the bond strength of composite resin restorations for Er: YAG laser irradiated dentin was improved by removing the denatured dentin layer with a steel burr or air abrasion.
The aim of this study was to evaluate adolescents’ acceptance and pain perception of Er-YAG laser preparation in comparison to conventional mechanical preparation. Material and methods: Forty four ...adolescents between the age of 16 and 18 years with bilateral matched pairs of carious permanent molars participated in this study. In each patient one of the 2 cavities was prepared conventionally, the other with the Er-YAG laser. All cavities were restored with light-cured composite resin following the application of acid etch and a bonding agent. The patients were instructed to rate pain (sensitivity) during treatment according to visual analogue scale and to decide which method they would prefer for their future caries treatment. Results: The patients rated lower pain perception during laser treatment. It was found that 86.36 % of the adolescents indicated that they would prefer the Er:YAG laser preparation for further caries treatment. Conclusion: The application of the Er-YAG laser for carious tissue removal, compared to conventional mechanical preparation, is perceived as more comfortable and the adolescents prefer it for a future treatment.
The present study examined the effects on dentin ablation efficiency arising from various pulse durations of Er: YAG laser at a fixed energy fluence. Ten flat human dentin disks were prepared and ...exposed to an Er: YAG laser at 1 pps for three seconds at pulse durations of 100—500 μsec with 150 mJ/pulse (40.0 J/cm2•pulse). The depth and diameter of the ablated dentin were measured and the ablation volume was estimated. Irradiated surfaces and cross-sections were observed using a SEM. Depth of the removed dentin increased and the diameter of the spot decreased without a change in the estimated volume at increased pulse durations. SEM observation of the irradiated surfaces revealed that there were no morphological differences when the pulse duration was changed. When the specimens were cross-sectioned, the ablated dentin had a dome shape and there was a dark layer under the irradiated surface.
Composite scaffolds obtained by the combination of biodegradable porous scaffolds and hydroxyapatite with bone regeneration potential are feasible materials for bone tissue engineering. However, most ...composite scaffolds have been fabricated by complicated procedures or under thermally harsh conditions. We have previously demonstrated that hydroxyapatite coating onto various substrates under a thermally mild condition was achieved by erbium-doped yttrium aluminum garnet (Er: YAG) pulsed laser deposition (PLD). The purpose of this study was to prepare a polycaprolactone (PCL) porous scaffold coated with the hydroxyapatite by the Er: YAG-PLD method. Hydroxyapatite coating by the Er: YAG-PLD method was confirmed by morphology, crystallographic analysis, and surface chemical characterization studies. When cultured on PCL porous scaffold coated with hydroxyapatite, rat bone marrow-derived mesenchymal stem cells adhered, spread, and proliferated well. The micro-CT and staining analyses after the implantation of scaffold into the critical-sized calvaria bone defect in rats indicate that PCL porous scaffold coated with hydroxyapatite demonstrates accelerated and widespread bone formation. In conclusion, PCL porous scaffold coated with hydroxyapatite obtained by the Er: YAG-PLD method is a promising material in bone tissue engineering.
This study evaluated the effect of chitosan on dentin treatment after selective removal of caries lesions with Er:YAG laser in reducing
Streptococcus mutans
, as well as its effect on the performed ...restorations. The sample consisted of children (aged 7 to 9 years) with active carious lesions and dentin cavitation located on the occlusal surface of deciduous molars. Eighty teeth were randomly distributed into 4 groups according to the caries removal method: Er:YAG laser (250 mJ/4 Hz) or bur and dentin surface treatment: 2.5% chitosan solution or distilled water. The bacterial load of caries-affected dentin was quantified by counting CFU/mg (
n
= 10). The teeth were restored and evaluated at 7 days, 6 months, and 12 months using modified USPHS criteria (
n
= 20). Microbiological data was analyzed by Mann–Whitney and clinical analyses were done using Kruskal–Wallis and Dunn test (
α
= 0.05). The results showed that the Er:YAG laser significantly reduced the amount of
Streptococcus mutans
(
p
= 0.0068). After dentin treatment with chitosan, there was a significant reduction in the amount of
Streptococcus mutans
for both removal methods (
p
= 0.0424). For the retention and secondary caries criteria, no significant differences were observed along the evaluated time (
p
> 0.05). The laser-treated group was rated “bravo” for discoloration (
p
= 0.0089) and marginal adaptation (
p
= 0.0003) after 6 and 12 months compared to baseline. The Er:YAG laser reduced the amount of
Streptococcus mutans
and the chitosan showed an additional antibacterial effect. After 1 year, the Er:YAG laser-prepared teeth, regardless of the dentin treatment, showed greater discoloration and marginal adaptation of the restorations.
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