Effect of low fluency dentin conditioning on tensile bond strength of composite bonded to Er:YAG laser-prepared dentin: a preliminary study

Micro-Morphological Features of the Er:YAG-Lased Interface in Primary Teeth: 12 Months Randomized Split-Mouth Trial

Despite considerable improvements in oral health, dental caries remains a public health issue. The most frequently used technique to remove caries is through rotating drills. New minimally invasive strategies were introduced into dental practice, such as the use of lasers to perform highly controlled tissue ablation while limiting pain and discomfort, as well as overcoming drill phobia. The objective was to assess and compare treatment with Er:YAG laser versus a conventional rotary treatment during cavity preparation in children with regard to bond interface quality. In a randomized trial using a split-mouth design, 40 (9-12 year-old) children with 80 carious primary molars were included. The cavity in one quadrant was treated conventionally using a bur, while the cavity in the other quadrant was prepared using an Er:YAG laser. Twenty restored teeth were extracted after one year. The SEM histological evaluation of bond interface results demonstrated no statistically significant differences between restorations placed following bur preparation and those placed following the Er:YAG laser preparation, and both treatments demonstrated promising results. Over a one-year period, no statistically significant differences in the bond interface quality were observed following class I cavity preparation in primary teeth with either Er:YAG laser or a conventional rotary bur.

Effect of Er: YAG laser irradiation with additional low energy on resin-dentin bonding and morphology of bonded interface

OBJECTIVES

To examine the micro tensile bond strength (μTBS) and the resin-dentin interface on a laser-irradiated dentin surface using two different irradiation methods, with or without additional low-energy irradiation.

METHODS

The flat bovine dentin surface was divided into three groups: i). control group (C group, no irradiation), ii) 80 mJ/pulse Er: YAG laser group (80 group), iii) 80 + 30 mJ/pulse Er: YAG laser group (80 + 30 group, with an additional 30 mJ/pulse). After the roughness of the dentin surface was recorded, Clearfil SE Bond 2 or Clearfil Universal Bond Quick (Kuraray Noritake Dental Inc., Tokyo, Japan) was applied. After the μTBS testing, the failure mode was observed. The bonded interface was assessed using Rhodamine-dye incorporated adhesives and observed by optical coherence tomography.

RESULTS

The dentin surface showed opened dentinal tubules without a smear layer after irradiation. For both adhesives, the μTBS was significantly higher in 80 + 30 group than in the 80 group (p < 0.05). In the 80 group, the thickness of the adhesive layer was not uniform, and the dentin surface was occasionally in direct contact with the composite resin. The failure mode images showed that most of the fractures in the 80 group were at the sub-surface of irradiated dentin. The adhesive layers of the 80 + 30 groups were homogeneous.

CONCLUSIONS

The dentin surface was rough and irregular by 80 mJ irradiation, which might result in an inadequate resin-dentin interface and the weak μTBS. The bonded integrity was mitigated by additional irradiation.

Effects of Er:YAG and Er,Cr:YSGG laser irradiation and adhesive systems on microtensile bond strength of a self-adhering composite

This study was aimed to evaluate the effects of Er:YAG and Er,Cr:YSGG laser irradiation and adhesive systems on the microtensile bond strength of Fusio Liquid Dentin (FLD) which is a self-adhering composite (SAC). Twenty-four freshly extracted human molar teeth were collected, and the enamel was removed from the occlusal surface to obtain a flat dentin surface. Twenty-four teeth were randomly divided into eight groups: Group 1: only Fusio Liquid Dentin (FLD) (Petron Clinical, Orange, California, USA) was applied to the dentin surface; Group 2: 37% Phosphoricacid (i-GEL, Medicinos Linija UAB, Lithuania) + FLD; Group 3: Single Bond Universal (SBU) (3 M ESPE, Germany) + FLD; Group 4: Adper Easy One (AEO) (3 M ESPE, Germany) + FLD; Group 5: Er:YAG laser + AEO + FLD; Group 6: Er:YAG laser + SBU + FLD; Group 7: Er,Cr:YSGG laser + AEO + FLD; and Group 8: Er,Cr:YSGG laser + SBU + FLD. After thermocycling, 1 × 1 mm2 sticks were used for the µTBS test (n = 10). Two sticks per group were used for SEM analysis. Fractured sample surfaces were evaluated using a stereomicroscope. Group 8 showed the highest µTBS value (13.70 MPa), whereas Group 1 showed the lowest μTBS value (5.60 MPa). There were no significant differences between Groups 2, 3, and 4 (P = 0.324), but Groups 5-8 showed statistically significant results that were higher than Groups 1-4 (P = 0.012). Adhesive failure mode was predominant followed by mixed failure. The evaluation of bonding of the FLD to dentin showed that the combined use of Er:YAG and Er,Cr:YSGG lasers with SBU and AEO on dentin surfaces improved the dentinal bond strength of the FLD.

Influence of Low-Level Laser Modification and Adhesive Application Mode on the Bonding Efficiency of Universal Adhesives to Er:YAG Laser-Ablated Dentin

Introduction: Erbium laser ablation as a method of tooth preparation and conditioning has shown promising results. Although previous studies have adopted various combinations of different laser parameters and several dentin adhesive systems, very few have investigated combining high-level and low-level ER:YAG lasers with Universal adhesives. This study aimed to assess the impact of using low-energy irradiation on the surface micro-topography and shear bond strength (SBS) of universal adhesive (UA) to the erbium:yttrium-aluminum-garnet (Er:YAG) laser-ablated dentin substrate, bonded in etch-and-rinse or self-etch adhesive mode. Methods: Eighty-seven extracted molars were sectioned to expose flat occlusal dentin surface; 60 teeth were divided equally into three groups according to the surface treatment; bur-cutting (B), Er:YAG high-energy laser cutting (L₁ - 200 mJ, 20 Hz, 50 μs pulse), or L₁ followed by low-energy laser modification (L₁ /L₂ - 80 mJ, 10 Hz, 50 μs pulse). Then each group was equally divided into two groups (n=10) according to the mode of application of the universal adhesive; either etch-and-rinse (ER) or self-etching (SE). The samples were subjected to thermocycling (5000 cycle between 5°C and 55°C), and SBS was tested. Two-way ANOVA and Tukey post hoc test were used to analyze the results. The remaining 27 samples were used to investigate the effect of the treatment on the topography of the treated dentin surfaces using a scanning electron microscope (SEM). Results: B/SE recorded the highest SBS (25.48 ± 2.6 MPa) followed by B/ER (23.20 ± 6.8 MPa) and L₁ /L₂ /SE (22.94 ± 4.1 MPa) and with no statistically significant difference between these groups (P >0.05). The lowest SBS results (P <0.05) were recorded for L₁/SE (12.22 ± 3 MPa). No statistical differences were found between the SBS of L₁ /L₂ /ER and L₁ /ER groups or between the SBS of L₁ /L₂ / ER and L₁ /L₂ /SE groups. Conclusion: A subsequent treatment of the Er:YAG laser-ablated dentin with low-energy laser modification mode (LMM) enhances the SBS of the tested UA when applied in SE mode.

Effect of Er:YAG laser etching on topography, microstructure, compressive strength, and bond strength of a universal adhesive to calcium silicate cements

OBJECTIVE

To evaluate the effect of Er:YAG etching on topography, microstructure, compressive strength, and shear bond strength (SBS) of All-Bond Universal adhesive to mineral trioxide aggregate-Angelus (AMTA) and Biodentine (BD).

METHODS AND MATERIALS

Sixty cylindrical specimens of each cement (AMTA and BD) in five groups were prepared and stored for 72 h. The control groups were non-etched, and four other groups were acid-etched and laser-etched with a pulse energy of 60, 80, or 100 mJ, followed by compressive strength testing. Surface micromorphology and topography were evaluated. Similar groups were bonded using All-Bond Universal with self-etch and etch-and-rinse (acid-etch) approaches, and laser-etch 60, 80, and 100 mJ, and SBS was tested. Data were analyzed using two-way and one-way ANOVA and the Bonferroni post hoc tests (α = 0.05).

RESULTS

BD had a significantly higher compressive strength and SBS (except for laser-etch 100) compared to AMTA, regardless of the etching method (p < 0.001). Acid etching and laser etching 100 of both cements and laser etching 80 of BD alone produced a significantly lower compressive strength than that for the other groups. Contrary to BD, for AMTA, all the treatments significantly increased SBS compared to that of the self-etch group.

CONCLUSIONS

Etching of AMTA was needed for stronger bonding; laser etching with 60 or 80 mJ without compromising compressive strength was recommended. Etching not only did not improve bonding ability of BD, but it also negatively affected the strength of BD.

CLINICAL RELEVANCE

To achieve successful combined calcium silicate cement-resin material restoration, an adequate bond between the materials is mandatory. This might be provided with the ultramild adhesive through laser etching without compromising compressive strength, depending on cement composition and laser energy level used.

Effect of Er:YAG laser energy densities on thermally affected dentin layer: Morphological study

BACKGROUND AND AIMS

Physical and chemical composition of dentin is subject to modification when irradiated with Er:YAG laser. Temperature rise causes water evaporation and micro-mechanical ablation of dentin. The misuse of laser parameters could affect negatively dentin collagen fibers leading to failure in bonded composite restorations. The aim of this in vitro study was to evaluate the effect of Er:YAG laser radiation at different levels of energy on the morphology of thermally affected dentin layer.

MATERIALS AND METHODS

Forty-eight freshly extracted human third molars were randomly divided into six groups (n = 8). In all groups, except for the control groups, dentin was subject to irradiation with H02 handpiece Er:YAG laser in non-contact mode (SSP mode = 50 µs; 10 Hz; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min) with the following levels of energy (40, 60, 80, 100, and 120 mJ) respectively. Teeth were sliced longitudinally. Photo-ablated cavities were observed. The cavity depth and dentin fiber collagen deterioration were measured.

RESULTS

Laser irradiation increased the depth of dentinal crater from 46.57 µm to 178.2 µm, when energy level increased from 40 mJ to 120 mJ. A superficial black layer, representing dentinal affected collagen fibers, was present in all groups except for control group. When comparing the thickness of the black layer, there was no significant difference between groups. It increased at 40 mJ to 28.17 µm then decreased to 15.19 µm at 60 mJ and then increased again for 80 mJ to 19.93 µm, 100 mJ to 22.87 µm and 120 mJ to 28.53 µm. Only one group (60 mJ) showed low values and significant difference as compared to the other irradiated groups, when multiple comparisons tests (ANOVA) were made using Newman-Keuls test.

CONCLUSION

Dentin organic matrix presented the minimum alteration when Er:YAG laser is used specifically at an appropriate level of energy (60 mJ).

Effect of different modes of erbium:yttrium aluminum garnet laser on shear bond strength to dentin

OBJECTIVES

The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of resin composites to dentin using total etch dentin bonding adhesives.

MATERIALS AND METHODS

Sixty extracted human molars were flattened to obtain dentin surfaces. The samples were divided into three groups (n = 20): Group I: 37% phosphoric acid + optibond FL + resin composite; Group II: Erbium:yttrium aluminum garnet (Er:YAG) laser (medium short pulse [MSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite; Group III: Er:YAG laser (quantum square pulse [QSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite. After the specimens were prepared, the SBS test was performed at a crosshead speed of 0.5 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Statistical analyses were performed with one-way ANOVA and Tukey's honestly significant difference tests. One sample of treated dentin surface from each group was sputter-coated with gold, and scanning electron microscope (SEM) images were captured.

RESULTS

Acid etching showed significantly higher SBS than the other groups (P < 0.05). However, the difference between Er:YAG MSP and QSP mode groups was not statistically significant (P > 0.05). SEM images of the acid-etched dentin surface showed opened dentinal tubule with a regular surface, but Er:YAG MSP mode treated surface was irregular. The surface treated with Er:YAG QSP mode represented wide dentinal tubules with a clean and flat surface.

CONCLUSION

Using different modes (MSP and QSP) of Er:YAG laser for dentin surface treatment before application of total etch adhesives is still not an sufficient alternative compared to acid etching.

Assessment of microleakage of class V restored by resin composite and resin-modified glass ionomer and pit and fissure resin-based sealants following Er:YAG laser conditioning and acid etching: in vitro study

Aim

The aim of this study was to make a comparison between microleakage of conventionally restored class V cavities using acid etchant and the ones conditioned by erbium-doped yttrium aluminum garnet (Er:YAG) laser, and also to assess and compare the effectiveness of enamel surface treatments of occlusal pits and fissures by acid etching and conditioned by Er:YAG laser-etch.

Materials and methods

Seventy-two extracted third molars were used in this study. The samples were divided into two major groups: class V cavities and pit and fissure sealants. Each subgroup was divided into conventional acid etching, Er:YAG laser conditioning and conventional acid etching, and combination with Er:YAG laser conditioning (n=12). The teeth were placed in 2% methylene blue dye solution, were sectioned, and were evaluated according to the dye penetration criteria. Two samples per subgroup were chosen for scanning electron microscopic (SEM) analysis.

Results

There was a significant difference between occlusal and cervical margin groups. Laser conventional composite cementum group showed more microleakage values compared to other groups. There was no significant difference between occlusal margin groups. However, there was a significant difference between cervical margin groups in terms of microleakage. In sealant groups, there was a significant difference between laser and conventional with/without laser treatment groups in terms of microleakage.

Conclusion

Based on the results reported in this study, it can be concluded that the application of the Er:YAG laser beneath the resin composite, the resin-modified glass ionomers (GIs), and the fissure sealant placement may be an alternative enamel and dentin etching method to acid etching.

Effect of Airborne Particle Abrasion on Microtensile Bond Strength of Total-Etch Adhesives to Human Dentin

Aim of this study was to investigate a specific airborne particle abrasion pretreatment on dentin and its effects on microtensile bond strengths of four commercial total-etch adhesives. Midcoronal occlusal dentin of extracted human molars was used. Teeth were randomly assigned to 4 groups according to the adhesive system used: OptiBond FL (FL), OptiBond Solo Plus (SO), Prime & Bond (PB), and Riva Bond LC (RB). Specimens from each group were further divided into two subgroups: control specimens were treated with adhesive procedures; abraded specimens were pretreated with airborne particle abrasion using 50 μm Al₂O₃ before adhesion. After bonding procedures, composite crowns were incrementally built up. Specimens were sectioned perpendicular to adhesive interface to produce multiple beams, which were tested under tension until failure. Data were statistically analysed. Failure mode analysis was performed. Overall comparison showed significant increase in bond strength (p < 0.001) between abraded and no-abraded specimens, independently of brand. Intrabrand comparison showed statistical increase when abraded specimens were tested compared to no-abraded ones, with the exception of PB that did not show such difference. Distribution of failure mode was relatively uniform among all subgroups. Surface treatment by airborne particle abrasion with Al₂O₃ particles can increase the bond strength of total-etch adhesives.

Dental Adhesion to Erbium-Lased Tooth Structure: A Review of the Literature

OBJECTIVE

The aim of the present study was to conduct a review of the literature about adhesion on erbium laser prepared cavities, related to the specific conditions of the irradiated dentin substrate and the effects on bond strength values.

BACKGROUND DATA

Advances in adhesive restorative techniques significantly influenced modern restorative dentistry. The concept of "minimally invasive dentistry" aims to perform more conservative treatment of cavities in which the removal of sound dentin is no longer necessary. This approach, which relies on the concept of adhesion of restorative materials to the mineralized dental tissues, is considered to be a contemporary outcome in dentistry. Similarly, laser technology in restorative dentistry opened new possibilities and strategies as alternatives to conventional treatment. Considering the clinical aspects of the use of erbium lasers for caries removal, cavity preparations, and substrate conditioning, treatment with lasers can be considered to be an efficient technique with wide acceptance by patients.

METHODS

Computerized and manual searches were conducted for studies through 2015 that addressed the topic.

RESULTS

According to the literature, there is no defined standard protocol concerning the information that articles must provide, making a definitive protocol very difficult to establish. Data varied from the type of adhesive and resin composite used, substrate, and parameters (power, energy density, pulse duration, irradiation time, distance, cooling system) to the bond strength test methodology used.

CONCLUSIONS

Further studies are necessary in order to define a standard protocol with positive results and higher bond strength values when using erbium lasers. Detailed information concerning laser parameters should be implemented. Also, longitudinal clinical studies should be developed in the search for new parameters that behave favorably in the irradiated substrate.

The Effect of Energy Densities on the Shear Bond Strength of Self-Adhering Flowable Composite to Er:YAG Pretreated Dentin

Objective. To investigate the shear bond strength of self-adhering flowable resin composite, to dentin, after exposing it to Er:YAG laser radiation, at different energy densities. Materials and Methods. Sixty freshly extracted human third molars were randomly divided into five groups (n = 12). In the control group, dentin was left unirradiated, whereas, in the other four groups, dentin was irradiated with Er:YAG laser in noncontact mode (MSP mode = 100 µs; 10 Hz; beam diameter: 1.3 mm; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min), and respectively, with the following level of energy (50 mJ, 60 mJ, 80 mJ, and 100 mJ). Then, self-adhering flowable resin composite was bonded to all prepared dentin surfaces. Shear bond strength (SBS) was applied and fractured surfaces were examined using scanning electron microscopy. Results. SBS values showed significant differences in 60 mJ (P < 0.05) compared to other groups. Morphological evaluation revealed tags or plugs in dentinal tubules, especially when 60 mJ and 80 mJ were used. All four groups tended to leave more residues on the dentin surface, than the control group. Conclusion. Er:YAG dentin irradiation may enhance SBS of the self-adhering flowable resin composite when it is used at the appropriate low level of energy density.

Evaluation of Er,Cr:YSGG Laser Effect on Microshear Bond Strength of a Self-Adhesive Flowable Composite in the Dentin of Permanent Molar: An In Vitro Study

Aim and Background. Recently, new restorative materials such as self-adhesive flowable composites, because of their simple use and no need to bonding and etching, are considered important, particularly in pediatric dentistry. The aim of this study is to evaluate the effect of Er,Cr:YSGG laser on microshear bond strength of self-adhesive flowable composite on permanent teeth dentin in vitro. Material and Methods. In this experimental study, 40 dentin sections were prepared from healthy third molars and divided into two groups according to their surface preparation by Er,Cr:YSGG laser or without laser, only with silicon carbide paper. In each group, two groups of 10 teeth were treated with self-adhesive flowable composite (Dyad) and conventional flowable composite (acid etch and bonding). Samples were stored in normal saline and after 48 hours their bond strength was measured. The failure mode of samples was observed on stereomicroscope. In order to analyse the results, the one way ANOVA and Tukey's test for multiple comparisons were used. Result. The maximum bond strength was related to conventional flowable composite with laser preparation group (24/21 Mpa). The lowest one was seen in Dyad composite without laser emitting (9/89 Mpa). The statistical difference between this two groups was significant (P value = 0/0038). The microshear bond strength differences between Dyad composite groups with laser preparation (mean = 16/427 ± 1/79) and without laser preparation (mean = 12/85 ± 1/90) were statistically significant too (P value = 0/01). Conclusion. Self-adhesive flowable composite has lower microshear bond strength than conventional flowable composite. Moreover, the laser irradiation as a surface treatment can improve this bond strength.

A Comparative Study of Microleakage on Dental Surfaces Bonded with Three Self-Etch Adhesive Systems Treated with the Er:YAG Laser and Bur

Aim. This study sought to compare the microleakage of three adhesive systems in the context of Erbium-YAG laser and diamond bur cavity procedures. Cavities were restored with composite resin. Materials and Methods. Standardized Class V cavities were performed in 72 extracted human teeth by means of diamond burs or Er-YAG laser. The samples were randomly divided into six groups of 12, testing three adhesive systems (Clearfil s³ Bond Plus, Xeno® Select, and Futurabond U) for each method used. Cavities were restored with composite resin before thermocycling (methylene blue 2%, 24 h). The slices were prepared using a microtome. Optical microscope photography was employed to measure the penetration. Results. No statistically significant differences in microleakage were found in the use of bur or laser, nor between adhesive systems. Only statistically significant values were observed comparing enamel with cervical walls (p < 0.001). Conclusion. It can be concluded that the Er:YAG laser is as efficient as diamond bur concerning microleakage values in adhesive restoration procedures, thus constituting an alternative tool for tooth preparation.

Short-pulse Er:YAG laser increases bond strength of composite resin to sound and eroded dentin

This study evaluated the influence of the irradiation with a short-pulse Er:YAG laser on the adhesion of composite resin to sound and eroded dentin (SD and ED). Forty-six samples of occlusal dentine, obtained from human molars, had half of their surface protected, while the other half was submitted to erosive cycles. Afterward, 23 samples were irradiated with Er:YAG laser, resulting in four experimental groups: SD, sound irradiated dentine (SID—Er:YAG, 50  μs 50  μs , 2 Hz, 80 mJ, and 12.6  J/cm 2 12.6  J/cm2 ), ED, and eroded irradiated dentin (EID—erosion + Er:YAG laser). A self-etching adhesive system was used, and then cylinders of composite resin were prepared. A microshear bond strength test was performed after 24 h storage (n=20 n=20 ). The morphology of SD and ED, with or without Er:YAG laser irradiation, was evaluated under scanning electron microscopy (n=3 n=3 ). Bond strength values (MPa) were subjected to analysis of variance followed by Tukey’s test. Statistically significant differences were found among the experimental groups: SD (9.76±3.39  B 9.76±3.39  B ), SID (12.77±5.09 A 12.77±5.09 A ), ED (5.12±1.72 D 5.12±1.72 D ), and EID (7.62±3.39 C 7.62±3.39 C ). Even though erosion reduces the adhesion to dentin, the surface irradiation with a short-pulse Er:YAG laser increases adhesion to both ED and SD.

Effect of different surface treatments on the shear and microtensile bond strength of resin-modified glass ionomer cement to dentin

OBJECTIVE

The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (μTBS) and shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) to dentin.

MATERIALS AND METHODS

Fifty-two extracted human molars were flattened to obtain dentin surfaces. For SBS assessment 40 teeth were divided into four groups according to their surface treatments (acid etching, Er:YAG laser QSP mode, Er:YAG laser MSP mode and control-SiC) (n = 10). A plastic cylinder was placed over the differently treated dentin surfaces and RMGIC was placed into the rings and polymerized. Twelve teeth were used for the μTBS test. The treated dentin surfaces described above were restored with 4 mm high RMGIC and light cured; then, the specimens were sectioned into serial sticks (n = 15) and μTBS and SBS were tested for failure in a testing machine with a 1 mm/min crosshead speed. The data were analyzed by one-way ANOVA and Tukey HSD tests (α = 0.05).

RESULTS

Acid etching showed significantly higher SBS than the other groups (p < 0.05). Er:YAG QSP and MSP-treated groups showed higher SBS values than the control group, but the difference was not statistically significant (p > 0.05). Er:YAG MSP showed the highest μTBS value followed by acid etching, whereas the control group exhibited the lowest value (p < 0.05) and the differences between the control group and Er:YAG QSP were not significant (p > 0.05).

CONCLUSIONS

The application of Er:YAG MSP mode and acid etching to dentin can be used for improving the bond strength of RMGIC.

Effect of different surface treatments on the microtensile bond strength of two self-adhesive flowable composites

The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (μTBS) of two different self-adhesive flowable composite materials (SACs) to dentin. Forty extracted human molars were horizontally flattened to expose the dentin surfaces. The teeth were divided into eight groups according to the surface treatments (acid etching, Er:YAG laser quantum square pulse (QSP) mode, and Er:YAG laser medium-short pulse (MSP) mode at 10 Hz, 1.2 W, 120 mJ, and control-SiC) and SAC type (Vertise Flow and Fusio Liquid Dentin) (n = 5). Light cured 4-mm-high composite build-ups were made on the dentin surfaces, and the specimens were sectioned into serial sticks (n = 15). Later, the specimens were attached to microtensile testing machine and tensile force was applied at a crosshead speed of 1 mm/min until failure occurred. The failure modes were evaluated using a stereomicroscope at ×40 magnification, and one sample from each group was used for scanning electron microscopy (SEM) evaluation. The data were analyzed with two-way ANOVA and Tukey's HSD test (α = 0.05). In all surface treatment groups along with the control groups, Vertise Flow showed better μTBS than the Fusio Liquid Dentin with the exception of the Er:YAG MSP mode surface treatment (p < 0.05). Etching with phosphoric acid and the Er:YAG QSP mode surface treatment significantly increased the μTBS of Vertise Flow (p < 0.05). Etching with phosphoric acid, Er:YAG QSP mode surface treatment, and Er:YAG MSP mode surface treatment significantly increased the μTBS of Fusio Liquid Dentin (p < 0.05). The μTBS of Vertise Flow was higher than the μTBS of Fusio Liquid Dentin. The Er:YAG laser irradiation increased the μTBS of both self-adhesive flowable resin composites in two pulse modes tested (MSP or QSP). However, the highest μTBS was recorded when Vertise Flow was applied with acid etching.

Comparison of tensile bond strengths of four one-bottle self-etching adhesive systems with Er:YAG laser-irradiated dentin

This study aimed to investigate the interaction of current one-bottle self-etching adhesives and Er:YAG laser with dentin using a tensile bond strength (TBS) test and scanning electron microscopy (SEM) in vitro. Two hundred and thirteen dentin discs were randomly distributed to the Control Group using bur cutting and to the Laser Group using an Er:YAG laser (200 mJ, VSP, 20 Hz). The following adhesives were investigated: one two-step total-etch adhesive [Prime & Bond NT (Dentsply)] and four one-step self-etch adhesives [G-Bond plus (GC), XENO V (Dentsply), iBond Self Etch (Heraeus) and Adper Easy One (3 M ESPE)]. Samples were restored with composite resin, and after 24-hour storage in distilled water, subjected to the TBS test. For morphological analysis, 12 dentin specimens were prepared for SEM. No significant differences were found between the control group and laser group (p = 0.899); dentin subjected to Prime & Bond NT, XENOV and Adper Easy One produced higher TBS. In conclusion, this study indicates that Er:YAG laser-prepared dentin can perform as well as bur on TBS, and some of the one-step one-bottle adhesives are comparable to the total-etch adhesives in TBS on dentin.

Effect of pretreatment on Er:YAG laser-irradiated dentin

Erbium:yttrium-aluminum-garnet (Er:YAG) laser preparation of tooth cavities for restoration is an increasingly popular method, but its compatibility with existing composite material bonding protocols has not been fully defined. This study evaluated the effect of laser and etchant pretreatments on the performance of one-bottle self-etch adhesives in Er:YAG laser-prepared dentin. Eight groups of 20 extracted teeth were established to investigate bonding in tested dentin disks. Various combinations of laser preparation (with/without), pretreatment (none/acid-etch/low-fluence Er:YAG irradiation), and self-etching adhesive (G-Bond Plus or Xeno V) were tested. Samples were then restored with composite resin and subjected to a tensile bond strength (TBS) test. We also performed scanning electron microscopy (SEM) on dentin disks from some of these groups before and after adhesive application to evaluate their microscopic morphological appearance. Statistical analysis (Dunnett T3 test coupled with the general linear model at 5% significance level) revealed that the laser preparation of dentin did not impact on TBS (p = 0.914), whereas pretreatment with either phosphoric acid (p < 0.0001) or low-fluence Er:YAG laser irradiation (p < 0.0001) significantly increased TBS, although there was no difference between them in their respective elevation of TBS. SEM analysis demonstrated that both acid and laser pretreatments reduced irregularities and produced a more homogeneous surface. Er:YAG laser preparation does not compromise the efficacy of one-step self-etch dentin adhesives, and pretreatment with phosphoric acid or low-fluence Er:YAG laser can significantly increase the TBS of adhesion to this irradiated dentin.

Influence of Er:YAG and Ti:sapphire laser irradiation on the microtensile bond strength of several adhesives to dentin

The aim of the present study was to evaluate the influence of erbium:yttrium-aluminum-garnet (Er:YAG) and Ti:sapphire laser irradiation on the microtensile bond strength (MTBS) of three different adhesive systems to dentin. Flat dentin surfaces from 27 molars were divided into three groups according to laser irradiation: control, Er:YAG (2,940 nm, 100 μs, 2.7 W, 9 Hz) and Ti:sapphire laser (795 nm, 120 fs, 1 W, 1 kHz). Each group was divided into three subgroups according to the adhesive system used: two-step total-etching adhesive (Adper Scotchbond 1 XT, from now on XT), two-step self-etching adhesive (Clearfil SE Bond, from now on CSE), and all-in-one self-etching adhesive (Optibond All-in-One, from now on OAO). After 24 h of water storage, beams of section at 1 mm(2) were longitudinally cut from the samples. Each beam underwent traction test in an Instron machine. Fifteen polished dentin specimens were used for the surface morphology analysis by scanning electron microscopy (SEM). Failure modes of representative debonded microbars were SEM-assessed. Data were analyzed by ANOVA, chi-square test, and multiple linear regression (p < 0.05). In the control group, XT obtained higher MTBS than that of laser groups that performed equally. CSE showed higher MTBS without laser than that with laser groups, where Er:YAG attained higher MTBS than ultrashort laser. When OAO was used, MTBS values were equal in the three treatments. CSE obtained the highest MTBS regardless of the surface treatment applied. The Er:YAG and ultrashort laser irradiation reduce the bonding effectiveness when a two-step total-etching adhesive or a two-step self-etching adhesive are used and do not affect their effectiveness when an all-in-one self-etching adhesive is applied.

Effect of laser preparation on bond strength of a self-adhesive flowable resin

The aim of this in vitro study was to evaluate the effect of laser treatment on shear bond strength of a self-adhesive flowable resin composite to human dentin. Eighty extracted sound human molar teeth were used for the study. The teeth were sectioned mesiodistally and embedded in acrylic blocks. The dentin surfaces were ground wet with 600-grit silicon carbide (SiC) paper. They were randomly divided into two preparation groups: laser (Er:YAG laser, with 12 Hz, 350 mJ energy) and control (SiC). Each group was then divided into two subgroups according to the flowable resin composite type (n = 20). A self-adhesive flowable (Vertise Flow) and a conventional flowable resin (Premise Flow) were used. Flowable resin composites were applied according to the manufacturer's recommendations using the Ultradent shear bond Teflon mold system. The bonded specimens were stored in water at 37 °C for 24 h. Shear bond strength was tested at 1 mm/min. The data were logarithmically transformed and analyzed using two-way analysis of variance and Student-Newman-Keul's test at a significance level of 0.05. The self-adhesive flowable resin showed significantly higher bond strength values to laser-prepared surfaces than to SiC-prepared surfaces (p < 0.001). The conventional flowable resin did not show such differences (p = 0.224). While there was a significant difference between the two flowable resin composites in SiC-prepared surfaces (p < 0.001), no significant difference was detected in laser-prepared surfaces (p = 0.053). The bond strength of a self-adhesive flowable resin composite differs according to the type of dentin surface preparation. Laser treatment increased the dentin bonding values of the self-adhesive flowable resin.

The effect of erbium family laser on tensile bond strength of composite to dentin in comparison with conventional method

The purpose of this study was to evaluate the effect of Er:YAG and Er,Cr:YSGG laser on tensile bond strength of composite resin to dentine in comparison with bur-prepared cavities. Fifteen extracted caries-free human third molars were selected. The teeth were cut at a level below the occlusal pit and fissure plan and randomly divided into three groups. Five cavities were prepared by diamond bur, five cavities prepared by Er:YAG laser, and the other group prepared by Er,Cr:YSGG laser. Then, all the cavities were restored by composite resin. The teeth were sectioned longitudinally with Isomet and the specimens prepared in dumbbelled shape (n = 36). The samples were attached to special jigs, and the tensile bond strength of the three groups was measured by universal testing machine at a speed of 0.5 mm/min. The results of the three groups were analyzed with one-way ANOVA and Tamhane test. The means and standard deviations of tensile bond strength of bur-cut, Er:YAG laser-ablated, and Er,Cr:YSGG laser-ablated dentine were 5.04 ± 0.93, 13.37 ± 3.87, and 4.85 ± 0.93 MPa, respectively. There is little difference in tensile bond strength of composite resin in Er,Cr:YSGG lased-prepared cavities in comparison with bur-prepared cavities, but the Er:YAG laser group showed higher bond strength than the other groups.

Micromorphology and adhesive performance of Er:YAG laser-treated dentin of primary teeth

This study evaluated (1) the micromorphology by scanning electron microscopy (SEM) and (2) the adhesive performance by microtensile bond strength (μTBS) of diamond bur-treated dentin compared to Er:YAG laser-treated dentin of human primary teeth. (1) For qualitative SEM evaluation, dentin of 18 second primary molars (n = 3/method) was treated with either diamond bur as a control (group 1a: 40 μm diamond bur only (clinical situation); group 1b: grinding + 40 μm diamond bur) or with Er:YAG laser (group 2a (clinical situation, manufacturer's settings): 200 mJ/25 Hz (5 W) + 100 mJ/35 Hz (3.5 W) laser only; group 2b (experimental setting "high"): grinding + 400 mJ/20 Hz (8 W); group 2c (manufacturer's setting "finishing"): grinding + 100 mJ/35 Hz (3.5 W); group 2d (experimental setting "low"): grinding + 50 mJ/35 Hz (1.75 W)). (2) For evaluation of adhesive performance, 64 second primary molars were divided into four groups and treated as described for group 1b and groups 2b/c/d (n = 16/method), and μTBS of Clearfil SE/Clearfil Majesty Esthetic to dentin was measured. The SEM micrographs were qualitatively analyzed. The μTBS values were compared with a Kruskal-Wallis test. The significance level was set at α = 0.05. SEM micrographs showed the typical micromorphologies with a smear layer for the diamond bur groups and open dentin tubules for all laser-treated groups. However, in group 2d, the laser beam had insufficiently irradiated the dentin area, rendering the underlying ground surface partly visible. There were no statistically significant differences between μTBS values of the four groups (p = 0.394). This suggests that Er:YAG laser treatment of dentin of primary molars provides bond strengths similar to those obtained following diamond bur treatment.