YSGG Laser Research Articles

Evaluation of Er,Cr:YSGG LASER in flapless functional crown lengthening (A randomized controlled clinical trial with microbial analysis)

Evaluation of Er,Cr:YSGG LASER in flapless functional crown lengthening (A randomized controlled clinical trial with microbial analysis)

Influence of Er,Cr:YSGG and Diode Lasers on The Microhardness of Enamel at Fissure area: (An in vitro Study)

Influence of Er,Cr:YSGG and Diode Lasers on The Microhardness of Enamel at Fissure area: (An in vitro Study)

Application of laser on enamel surface with three types of bioactive glasses-based resin infiltrants: An in vitro study

ObjectiveThe study aimed to evaluate and compare the surface micro-hardness, roughness, color, and morphology of enamel after Er,Cr:YSGG laser irradiation, followed by application of three types of bioactive glasses-based resin infiltrants, and the samples groups were challenged with the pH cycle. MethodologyExperimental photoactivated resin infiltrants were synthesized using dimethacrylate resins, whereby three different types of bioactive glasses (BGs), i.e., 45S5, fluoridated-BG (F-BG), and borosilicate-BG (B-BG), were incorporated into the resin system. Initially, white spot lesions were created artificially on the toosth enamel surface, then irradiated with Er,Cr:YSGG laser. Then, the resin-only and BG-based resins were infiltrated on the enamel surface. All samples were pH challenged for 14 days, and the micro-hardness, surface roughness, surface morphology, and color stability (ΔE) analyses were conducted before and after the 14 days pH challenge. ResultsAfter laser irradiation, the micro-hardness was significantly high with 45S5 group compared to resin-only (p = 0.021), F-BG (p = 0.042), and B-BG (p = 0.001) groups. After the pH challenge, the micro-hardness values for all groups were reduced significantly (p ≤ 0.05). The surface roughness was least with the resin-only group and showed a non-significant difference with F-BG (p = 0.34) and significant differences with both B-BG (p = 0.005), and 45S5 (p = 0.010) groups. After the pH cycle, the roughness of all groups was increased significantly (p ≤ 0.05), except B-BG group showed a non-significant difference (p = 0.528). The B-BG group showed significantly high ΔE between day 0 and baseline compared to resin-only (p = 0.0008), F-BG (p = 0.017), and 45S5 (p = 0.029), whereas between day 14 and baseline, the lowest ΔE value was observed for B-BG (14.2 ± 2.10) and maximum for the resin-only (20.57 ± 2.47) group. The SEM images showed pitting on the surface of all resin infiltrant groups after 14 days of pH challenge. ConclusionThe morphological difference was observed after the laser irradiation on the enamel surface. The differences in micro-hardness, surface roughness, and color were observed after the application of experimental resin infiltrants and significant differences were observed after the pH challenge.

Influence of lithium disilicate pretreatment using photodynamic therapy, non-thermal plasma, and laser treatment on surface roughness and bond strength

AimsTo assess the shear bond strength (SBS) and surface roughness (Ra) of lithium disilicate ceramic (LDC) after using different pretreatment methods i.e., Non-Thermal Plasma (NTP), self-etching ceramic primer (SECP), curcumin photosensitizer (CP), Er and Cr: YSGG lasers (ECL) in comparison to hydrofluoric acid + Silane (HF + S). Materials and methodsA total of fifty LDC discs were prepared. All the discs were arbitrarily divided into five groups based on the surface conditioning used (n = 10). Group 1: PDT+S, group 2: HF+ S, group 3: NTP + S, group 4: SECP, and group 5: ECL+ S. A confocal optical microscope was used to calculate Ra for each sample. A self-adhesive resin cement was applied followed by LED light curing. A universal testing machine was used to assess SBS and a stereomicroscope was used to determine the failure mode. Two-way analysis of variance (ANOVA), and a Tukey post hoc test was used to analyze data (p = 0.05). ResultsThe highest bond integrity of resin luting bonded to conditioned LDS ceramics were presented by group 2 (HF+ S) (21.48±1.39 MPa) and lowest by group 1 (CP+S) (13.01±1.19 MPa) respectively. Intergroup comparison analysis revealed that group 1(13.01±1.19 MPa) and group 3 (14.28±0.62 MPa) displayed comparable outcomes of bond integrity(p>0.05). Similarly, it was observed that group 2 (21.48±1.39 MPa) and group 5 (21.31±1.85 MPa) exhibited comparable values of bond strength(p>0.05). Specimens conditioned with HF+ S showed the highest Ra (1445.86±0.019 µm). However, discs treated with SECP exhibited the lowest Ra (0139.76±0.081 µm). ConclusionEr, Cr: YSGG laser retains the ability to be used as an LDC surface conditioner as an alternative to HF+ S.Both the methods of pretreatment results in high surface roughness of LDC.

Adhesive bond of Bioactive and bulk fill resin to disinfected caries affected dentin (lactobacillus specie) with laser and photodynamic therapy

AimsTo evaluate the antimicrobial effectiveness of cavity disinfectants chlorhexidine gluconate (CHX), Er, Cr, YSGG laser (ECL), and curcumin photosensitizer (CP) against Lactobacillus and shear bond strength (SBS) of Bioactive (BA) and bulk fill composite (BFC) restorative material bonded to carious affected dentin (CAD). Materials and MethodsSixty human mandibular molars scored 4 and 5 on the International Caries Detection and Assessment System (ICDAS) were included. After inoculating the specimens with lactobacillus specie all the samples were arbitrarily divided into three groups based on the disinfection regime used (n=20). Groups 1 and 2: CAD disinfection using ECL, Groups 3 and 4: CAD disinfection using CP, and Groups 5 and 6: CAD disinfection using CHX. After cavity sterilization, the survival rate was estimated and each group was further divided into two sub-groups based on the restorative material used. Groups 1, 3, and 5 (n = 10) were restored using BFC restorative material, and groups 2, 4, and 6 (n = 10) were restored using a conventional bulk-fill resin material. A universal testing machine (UTM) was used to determine the SBS and debonded surfaces were examined under a stereomicroscope to determine the modes of failure. Kruskal-Walis, ANOVA, and Post Hoc Tukey were applied to investigate the survival rate and bond strength values. ResultsECL group displayed the highest survival rate (0.73±0.13) of Lactobacillus. The least survival rate (0.17±0.09) was demonstrated by CP activated by PDT. Group 1 (ECL+ BA) treated specimens exhibited the maximum value of SBS (18.31 ± 0.22 MPa). However, group 3 (CP + BA) revealed the minimum values of bond strength (14.05 ± 1.02 MPa). The intergroup comparison revealed that group 1, group 2 (ECL+BFC) (18.11 ± 0.14 MPa), group 5 (CHX+ BA) (18.14 ± 0.36 MPa), and group 6 (CHX+BFC) (18.18 ± 0.35 MPa) displayed comparable outcomes of bond integrity (p>0.05). ConclusionCaries-affected dentin disinfected with Er, Cr: YSGG, and chlorhexidine improve bond scores of bioactive and conventional bulk-fill restorative material.

Adjunctive use of Er, Cr: YSGG laser, Potassium titanyl Phosphate laser, and photosensitizer on extrusion bond strength of radicular dentin to bioceramic sealers.

To assess the impact of adjunctive final root canal disinfection regime curcumin photosensitizer (CP) activated by Photodynamic therapy (PDT), Er, Cr: YSGG laser (ECL), and Potassium titanyl Phosphate (KTP) laser on the bond integrity of two endodontic Bioceramic (BC) sealers. Decoration of eighty human single-rooted teeth was performed up to a cementoenamel junction. After instrumentation, all samples were irrigated with 2.25% NaOCl solution followed by 17% EDTA. The specimens were divided arbitrarily into 8 groups (n=10) based on the adjunctive final irrigation method used. Group 1 and 5 (Control): No adjunctive regime, cleaned using 2.25% NaOCl+17% EDTA, group 2 and group 6: CP activated by PDT, Group 3 and Group 7 using ECL, Group 4 and Group 8: KTP laser. Following disinfection samples in groups 1, 2, 3, and 4 were obturated using Sankin apatite root canal sealer (SARS). Specimens in groups 5, 6, 7, and 8 were obturated using Pro-root endo sealer (PRES). Sectioning of samples was performed. The sectioned specimens were subjected to a compressive loading exerted via a steel plunger moving at a 0.5mm/min crosshead speed till debonding. Means and standard deviations (SD) of EBS of BC sealer with the root canal dentin were assessed using one-way analysis of variance (ANOVA) and Post Hoc Tukey multiple comparison tests. The level of significance was measured at p=0.05. The coronal section of samples in group 5 (Na-E-PRES) exhibited the highest bond value. The lowest PBS was displayed by the middle third of specimens in group 6. Group 1 (Na-E-SARS), group 3 (Na-E-ECL-SARS), group 5 (Na-E-PRES), and group 7 (Na-E-ECL-PRES) exhibited comparable bond values (p>0.05). Whereas, group 2 (Na-E-PDT-SARS) and group 4 (Na-E-PTPL-SARS), group 6 (Na-E-PDT-PRES), and group 8 (Na-E-PTPL-PRES) were found to be comparable (p>0.05). Adjunctive use of Er, Cr: YSGG laser displayed better extrusion bond strength with BC root canal sealer compared to CP activated by PDT and KTP laser. Bond strength is influenced by the type of irrigation.

Adjunctive use of different lasers Er, Cr: YSGG, femtosecond, potassium titanyl phosphate and photodynamic therapy on radicular disinfection bonded to glass fiber post.

The aim of this study was to evaluate and compare the effect of different laser prototypes [Er, Cr: YSGG laser (ECYL), potassium titanyl phosphate laser (KTP), and Femtosecond laser (FSL)]and curcumin photosensitizer (CP) activated by Photodynamic therapy (PDT) on the bond strength of Pre-fabricated fiber reinforced composite (PFRC) post-bonded to radicular dentin. A total of fifty mandibular single-rooted closed apex teeth were extracted carefully, assembled, and decoronated up to the cementoenamel junction. The working length of all specimens was determined by using a 10 K patency file and later, were cleaned and shaped with Protaper NiTi system using the crown down approach, dried, and obturated with gutta-percha using an AH Plus sealer. Post space was prepared by guiding peeso-reamer. Based on the method of disinfection, the samples were allocated to five groups (n=10) at random: samples in group 1: curcumin photosensitizer (CP) activated by PDT, samples in group 2 disinfected using 5.25% NaOCl+17% EDTA, samples in group 3 disinfected using 5.25% NaOCl+17% EDTA+FSL, specimens in group 4 sterilized using 5.25% NaOCl+17% EDTA+KTP and samples in group 5 cleaned with 5.25% NaOCl+17% EDTA+ECYL. The fiber post was cemented via self-etch resin cement into the post space. All specimens with posts were dissected perpendicularly into apical, middle, and coronal dentin and subjected to the universal testing machine for push-out bond strength (PBS) testing. Statistical analysis was performed using a One-Way analysis of variance and Post Hoc Tukey multiple comparison tests. The highest PBS was corroborated when the radicular canal was disinfected with 5.25% NaOCl +17% EDTA+ ECYL at all three root levels (coronal, middle, and apical) and the lowest was adjudicated by decontamination with CP activated by PDT at all inspected root levels. Intergroup comparison presented that specimens in group 2: 5.25% NaOCl+17% EDTA (control) and group 4: 5.25% NaOCl+17% EDTA+KTP revealed comparable PBS outcome to group 5 (p>0.05) while samples in group 3 revealed the equivalent PBS values to group 1 (p<0.05) at all three root levels. Er, Cr: YSGG laser and potassium titanyl phosphate laser when used in combination with the conventional canal disinfection 5.25% NaOCl and 17% EDTA demonstrated the highest push-out bond strength values at coronal, middle, and apical levels of the root.

The influence of pulse duration and exposure time of Er,Cr:YSGG laser on lithium disilicate laminate debonding, an in vitro study

Problem statementGrinding restorations, such as veneers, with rotary instruments, is the conventional removal approach. It may be accompanied by micro-fractures that affect the adjacent healthy dental structures. Differentiation of the veneer from the dental structure, as well as the resin cement, is not a highly selective procedure when rotary instruments are used. Moreover, the rotary instruments may lead to scratches and overheating of the enamel. Patient discomfort is another disadvantage, due to the noise of the drill. PurposeThe purpose of this in vitro study was to examine the effectiveness of a 2790 nm Er,Cr:YSGG laser to debond lithium disilicate laminate, utilizing two distinct pulse durations and various exposure times. The shear bond strength, intrapulpal temperature, and adhesive remaining index were evaluated. Methods and materialsThis study included three groups of 75 extracted permanent mandibular incisors: G1, G2 (laser-treated groups were classified according to the pulse duration) and C (control group). Twenty five samples were regarded for each group. Both test groups were irradiated with a 3 W output power of Er,Cr:YSGG laser, for a variety of time intervals (20 s, 30 s, 40 s, 50 s, and 60 s). Five samples were tested for each time interval. During irradiation, the temperature in the pulp chamber was monitored using a K-type thermocouple connected to a digital multilogger thermometer that was introduced into the prepared sample pulp chamber. Subsequently, the shear bond strength was measured for G1 and G2, in addition to the control group (no irradiation). The adhesive remaining index was examined microscopically. The area was measured and analysed, and then, transformed into scores for comparisons. Finally, One untreated sample and two other samples of the highest power value from laser-treated groups were examined for their surface morphology by scanning electron microscope (SEM). ResultsThe debonding protocols were safe relative to the intrapulpal protocol. The temperature rise after an exposure time of 50 s and 60 s was significantly different from an exposure time of 20 s, 30 s, and 40 s, in both groups (p < 0.05). Both G1 and G2 significantly outperformed the control group in shear bond strength. There was no significant difference between G1 and G2 at any of the tested exposure times (p > 0.05). Nevertheless, the 60 s exposure time showed the lowest shear bond strength. ConclusionRegarding intralpulpal temperature, both modes can be safely used to remove laminate veneers. In sum, an exposure time of 50 s and a pulse duration of 60 μs demonstrated superior results for SBS, adhesive remaining index, and temperature values. Clinical implicationLithium disilicate laminate veneers may be removed quickly, safely, and comfortably. Laser-assisted debonding of porcelain laminate veneer is recommended and does not cause any damage to the veneer or enamel surface.

A Comparison of Laser and Mechanical Surface Pretreatment Methods on Shear Bond Strength of Resin Composite to Resin-Modified Glass Ionomer.

Dentin margins have a higher microleakage than enamel in composite restorations due to weaker bond durability. Clinically, most margins are located apical to cementoenamel junction on the dentin or cementum. Different surface preparation methods may have dissimilar effects on the shear bond strength of resin-modified glass ionomer (RMGI) to composite resin, regarding the layering technique employed in restoration of these cavities. This study aimed to investigate the shear bond strength of RMGI to composite resin using different mechanical surface preparation methods. In this in vitro study, 72 RMGI samples were prepared in six groups (n=12): control, acid etching, air abrasion with aluminum oxide (Al2O3), bur, Er: YAG laser, and Er, Cr: YSGG laser groups. Two samples from each group were randomly examined under a scanning electron microscope (SEM). A bonding layer and composite resin were applied and cured. Then the samples were subjected to 5000-cycles thermocycling procedure. The shear bond strength was then evaluated using a universal testing machine. Finally, the failed surface of the samples was evaluated under a light microscope to examine the failure mode. For the statistical analysis, one-way ANOVA and Games-Howell post hoc test was used to compare quantitative variables and chi-squared test to investigate the relationship between the failure mode and the groups. The significant level was set at 0.05. The results showed significant differences between the mean of the strength variable in the groups (p< .001). The acid-etch and air abrasion groups exhibited significantly the lowest and highest values, respectively. The chi-squared test results also showed a significant relationship between the failure mode in the study groups (p= .008). Acid etching before completing RMGI polymerization could adversely affect shear bond strength. The air abrasion and bur methods are among the best methods to increase the shear bond strength between composite resin and RMGI. Using Er, Cr: YSGG and Er: YAG lasers could increase the bond strength results.

Comparison of Er,Cr:YSGG laser and diode laser in the treatment of gingival melanin pigmentation: a randomized clinical trial.

This investigation has aimed to compare the efficiency of clinical depigmentation and repigmentation rate of erbium chromium-doped: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) and diode lasers during a 1-year follow-up and to evaluate patient satisfaction. Twenty-two participants were divided into Er,Cr:YSGG laser and diode laser groups using computer-aided randomization. Dummett Oral Pigmentation Index (DOPI) and photographic assessment with ImageJ Software version 10.2 were performed at the preoperative period and postoperative 1st month, 6th month, and 12th month. Moreover, the study assessed intra- and postoperative intensities of pain and postoperative patient aesthetic satisfaction using the Visual Analog Scale in both groups. The median values of DOPI did not differ statistically between the groups according to time (p > 0.05). In the Er,Cr:YSGG group, the extension of repigmentation was less as compared to the diode group at 1-year follow-up (p = 0.045). In the Er,Cr:YSGG group, the patients felt less intraoperative pain and discomfort compared to the diode group (p = 0.007). No significant differences were found between the two groups in terms of patient aesthetic satisfaction at the 1st and 12th months. The findings indicate that diode and Er,Cr:YSGG lasers can be used safely in depigmentation treatment, while the Er,Cr:YSGG laser has been shown to have superiorities in pain management and patient comfort parameters. Clinical Trial No.: NCT05304624.

2.79 μm Cr,Er:YSGG laser with a high energy realized by thermal bonding and concave end-face

We demonstrate the influence of thermal bonding and concave end-face on the 2.79 μm laser performance of Cr,Er:YSGG crystal. The simulation results of temperature distribution suggest that the two pure YSGG crystals bonded on the Cr,Er:YSGG as end-caps are beneficial to improve the heat dissipation capability. The experimental results of thermal focal length show that the thermal effects of un-bonding, planar thermal bonding, and concave thermal bonding Cr,Er:YSGG crystals are in descending tendency. The maximum output energies and slope efficiencies for concave thermal bonding Cr,Er:YSGG crystal are 3.480 J, 3.33 %@5 Hz; 2.126 J, 3.65 %@10 Hz; 1.384 J, 3.63 %@15 Hz; 1.155 J, 3.65 %@20 Hz, respectively, and the beam quality factors Mx2/ My2 are determined to be 7.68/8.63. The result is much better than the previous work, indicating that the xenon lamp pumped concave thermal bonding Cr,Er:YSGG crystal is a promising method to realize high energy laser output. All the results indicate that the thermal bonding and concave end-faces are promising methods to reduce the thermal effect and improve the laser performance of Cr,Er:YSGG crystal pumped by the xenon lamp.

Remineralization effects of Er,Cr:YSGG and/or bioactive glass on human enamel after radiotherapy-an in vitro study.

The aim was to evaluate the effects of Er,Cr:YSGG and/or bioactive glass 45S5 (BG) on the chemical and physical properties of enamel after radiotherapy. Third molar crowns were cut in half (buccal-lingually), and the mid part of the labial/oral surface was subjected to different protocols. All samples were treated with standard 70Gy. After radiotherapy, enamel was treated with either Er,Cr:YSGG (2780nm; pulse 60μs) and BG or only BG, and control samples were kept in deionized water. Vickers microhardness, scanning electron microscopy (SEM), and characteristic X-ray spectroscopy (EDS) were performed before, after radiotherapy, and after treatment. Analysis of variance (ANOVA) was used. A significant drop in enamel microhardness was observed after radiotherapy (p < 0.001). After Er,Cr:YSGG and BG or BG alone, there was a significant increase in microhardness (p < 0.001), which was on average significantly higher compared to the initial measurements for Er,Cr:YSGG with BG (p < 0.001), but not observed in BG alone (p = 0.331). After radiotherapy, SEM showed increased surface roughness with eroded prisms. Er,Cr:YSGG and BG or BG alone both showed disorderly packed glass particles on the enamel surface. Radiotherapy noticeably reduced the concentrations of calcium and phosphorus. Er,Cr:YSGG and BG treatment increased the concentrations of calcium, sodium, phosphorus, and silicate. BG treatment alone increased the concetration of calcium and phosphorus. Directly induced radiotherapy led to potential damage of enamel, but afterwards treatment with Er,Cr:YSGG laser and BG resulted in a higher increase of enamel microhardness compared to BG alone, reflecting in a possible better remineralization effect.

Evaluating the efficiency of Er,Cr:YSGG laser in removing adhesive remnants from tooth structure after orthodontic brackets debonding

Evaluating the efficiency of Er,Cr:YSGG laser in removing adhesive remnants from tooth structure after orthodontic brackets debonding

Laser Cleaning Improves Stem Cell Adhesion on the Dental Implant Surface during Peri-Implantitis Treatment

Dental implant therapy is a well-accepted treatment modality. Despite good predictability and success in the early stages, the risk of postplacement inflammation in the long-term periods remains an urgent problem. Surgical access and decontamination with chemical and mechanical methods are more effective than antibiotic therapy. The search for the optimal and predictable way for peri-implantitis treatment remains relevant. Here, we evaluated four cleaning methods for their ability to preserve the implant's surface for adequate mesenchymal stem cell adhesion and differentiation. Implants isolated after peri-implantitis were subjected to cleaning with diamond bur; Ti-Ni alloy brush, air-flow, or Er,Cr:YSGG laser and cocultured with mice MSC for five weeks. Dental bur and titanium brushes destroyed the implants' surfaces and prevented MSC attachment. Air-flow and laser minimally affected the dental implant surface microroughness, which was initially designed for good cell adhesion and bone remodeling and to provide full microbial decontamination. Anodized with titanium dioxide and sandblasted with aluminum oxide, acid-etched implants appeared to be better for laser treatment. In implants sandblasted with aluminum oxide, an acid-etched surface better preserves its topology when treated with the air-flow. These cleaning methods minimally affect the implant's surface, so it maintains the capability to absorb osteogenic cells for further division and differentiation.

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) (3M ESPE, Germany) + FLD; Group 4: Adper Easy One (AEO) (3M 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 (13.70MPa), whereas Group 1 showed the lowest μTBS value (5.60MPa). 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.

The effect of Er, Cr:YSGG laser debonding on the bond strength of two ceramic materials to dentin

ObjectivesEvaluating the bond strength of two ceramic materials to dentin after Er,Cr:YSGG laser debonding. Would laser debonding affect the bond strength of ceramic to dentin?Materials and methodsRecently extracted human molars were ground to expose dentin. Forty square shaped samples were prepared from CAD/CAM ceramic blocks. Samples were divided into two groups according to the type of ceramic material; group E: Lithium disilicate and group T: Ultra-translucent Zirconia (n = 20) Each group was divided into two subgroups (n = 10) according to the laser debonding effect (subgroup B: bonded samples, subgroup R: re-bonded samples after laser debonding). Ceramic samples were bonded to dentin using dual cure self-adhesive resin cement. Laser debonding of ceramic samples of subgroups R using Er, Cr:YSGG laser, were then re-bonded again to dentin surface with same resin cement. The Shear bond strength test using Universal testing machine was done. The failure mode was analyzed. Two-way analysis of variance was used to compare the mean bond strength and re-bond strength of two materials. The significance level was set at P ≤ 0.05.ResultsTwo-Way ANOVA showed that ceramic type had a significant effect on the re-bond strength to dentin. The predominant failure mode was adhesive.ConclusionsLaser debonding of Lithium disilicate and Ultra translucent Zirconia decreased the re-bond strength to dentin. Deterioration in re-bond strength for Lithium disilicate ceramics was more pronounced than for Ultra translucent Zirconia. Clinical Relevance Deterioration in the bond strength between ceramics & dentin after laser debonding still needs improvement to allow its clinical use.

Effect of Hydroxyapatite Coating in Combination with Physical Modifications on Microshear Bond Strength of Zirconia to Resin Cement.

Zirconia has been used as a reliable core material in dental restorations for years; however, its bonding to resin cement is a matter of challenge. Physical, chemical, and combinations of these techniques have been investigated to boost the properties of zirconia surface bonding. The objective of this work was to evaluate the effect of hydroxyapatite coating as a chemical therapy in combination with physical modifications on the microshear bond strength of the resin cement over zirconia. In the present research, 60 sintered zirconia blocks (4 × 4 × 4 mm) were randomized into four groups of 15, including Al2O3 particle abrasion (group 1), HA coating (group 2), Al2O3 particle abrasion + HA coating (group 3), and Er, Cr: YSGG laser irradiation + HA coating (group 4). The microshear bond strength was determined by bonding the blocks to the resin cement. The bond strengths (mean ± standard deviation) of modified zirconia surfaces were 16.93 ± 4.94 MPa, 16.14 ± 5.4 MPa, 19.4 ± 5.27 MPa, and 16.21 ± 3.7 MPa in groups 1-4, respectively. Test results of the ANOVA test revealed no significant difference regarding the bond strength values of zirconia surfaces to the resin cement between the studied preparation modalities (p > 0.05). Observations from the present study showed that HA coating can be as effective as the air-borne particle abrasion technique in improving bond strength to zirconia surfaces. Moreover, sandblasting by an aluminum oxide or Er, Cr: YSGG laser irradiation prior to HA coating of zirconia showed no significant effect on the reinforcement of bond strength values when compared to HA coating alone. The clinic hydroxyapatite coating alone or in combination with physical treatments improves the bond strength of zirconia to resin cement.

Passively Q-switched 3 μm erbium-doped solid state lasers using gold nanorods as broadband saturable absorber

The gold nanorods with an average aspect ratio of 30 were grown by the three-step seed-mediated wet chemistry growth method, resulting in a broadband spectral response in 3 μm region. Passive Q-switching operation of LD pumped 2.8 μm Er:YSGG and 2.9 μm Er:YAP laser was successfully realized by using the gold nanorods as saturable absorber. With regard to the Er:YSGG laser, the passively Q-switched pulses at 2796 nm with a maximum average output power of 234 mW, a minimum pulse width of 270.8 ns and a pulse repetition rate of 280.4 kHz were achieved. For the combination of Er:YAP and gold nanorods saturable absorber, a maximum average output power of 415 mW was obtained at 2919 nm. The minimum pulse width and pulse repetition rate were 313.2 ns and 196.8 kHz, respectively. The experimental results show that large-aspect-ratio gold nanorods can be used as a promising broadband saturable absorber to generate 3 μm short pulses.

Comparative Evaluation of Fibrin Network Formation after Root Conditioning using Erbium, Chromium-Doped Yttrium Scandium Gallium and Garnet Laser, Ethylene-Diamine-Tetra-Acetic Acid, and Tetracycline on Dentin: A Scanning Electron Microscopic Study.

Regeneration of periodontal tissues depend on the adhesion and development of fibrin clots to the root surface. Demineralization of the root surface ensures removal of smear layer uncovering dentin tubules and collagen matrix. Root conditioning agents were introduced to remove the smear layer and enhance the adhesion of blood components. The aim of the study was to determine the effect of erbium, chromium-doped yttrium, scandium, gallium and garnet (Er, Cr: YSGG) laser on smear layer removal (SLR) and fibrin network formation when compared to tetracycline, and ethylene-diamine-tetra-acetic acid (EDTA) for periodontal regeneration. The study was conducted at Amrita school of dentistry and the study design involves in vitro comparative study. Forty dentinal sections were prepared from freshly extracted teeth that were periodontally affected. The samples were divided into four groups: Scaling and root planing (SRP), tetracycline, EDTA, and Er, Cr: YSGG laser. The samples were assessed using a scanning electron microscope and photomicrographs were taken and analyzed for removal of smear layer, blood component adhesion (BCA), and fibrin network formation. Analysis of variance test and Kruskal-Wallis test with P < 0.05 considered to be statistically significant. There was a significant difference between Er, Cr: YSGG laser, tetracycline hydrochloride, and EDTA categories when compared with SRP categories. There was no significant difference between Er, Cr: YSGG laser, tetracycline, and EDTA according to SLR scoring and BCA scoring. It can be concluded that Er, Cr: YSGG laser-treated samples presented complete elimination of smear layer, formation of fibrin network, and BCA along with desensitizing effect for a better reduction in dentin hypersensitivity.

1,25-Dihydroxyvitamin D3: A Positive Factor for the Osteogenic Differentiation of hPDLSCs and for the Tissue Regenerative Activity of Cell Sheets

This study aims to investigate the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2VitD3) on osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and the activity of hPDLSC sheets and the differences in the tissue regeneration activity of hPDLSC sheets on tooth root fragment treated by different methods. Healthy caries-free premolars were collected. The hPDLSCs were obtained by enzymatic digestion. Surface markers of stem cells were analyzed by flow cytometry and the multidirectional differentiation ability of hPDLSCs was detected. During the osteogenic differentiation of hPDLSCs, 1,25(OH)2VitD3 was added and the effect of 1,25(OH)2VitD3 on osteogenic differentiation of hPDLSCs was assessed using Western blotting, quantitative reverse transcription–polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay, cell staining, and immunofluorescence. After hPDLSC sheets were prepared, histology and immunofluorescence analysis of the effect of 1,25(OH)2VitD3 on sheet activity were performed. In addition, root fragments were prepared and treated with scaling, 24% EDTA (ethylenediamide tetraacetic acid), and Er,Cr:YSGG lasers, respectively, and the tissue regeneration activity of hPDLSC sheets on different root fragments were observed. 1,25(OH)2VitD3 promoted the high gene and protein expressions of osteogenic markers ALP (alkaline phosphatase), Runx2, and OPN (osteopontin antibody) in hPDLSCs, along with enhanced ALP activity and staining, alizarin red staining, and immunofluorescence staining, indicating that the osteogenic differentiation ability of hPDLSCs was improved. Extracellular matrix secretion was increased in hPDLSC sheets, along with the positive expressions of the protein markers fibronectin and collagen I, suggesting that 1,25(OH)2VitD3 could enhance these effects. In addition, the root fragments treated by Er,Cr:YSGG laser were more suitable for the attachment and regeneration of hPDLSC sheets, demonstrating that 1,25(OH)2VitD3 could improve the tissue regeneration performance of these sheets. 1,25(OH)2VitD3 can promote osteogenic differentiation of hPDLSCs and thus plays an active role in hPDLSC sheet formation and tissue regeneration. In addition, the Er,Cr:YSGG laser can be used as the recommended treatment method for the root surface regenerated by hPDLSCs.