Laser Group Research Articles

The effect of bone remodeling with photobiomodulation in dentistry: a review study.

Photobiomodulation (PBM) has been emerging as a promising alternative therapy in dentistry. However, various parameters of PBM are used in different studies, and there is limited cumulative data on PBM for improving bone formation in clinical trials. The aim of this review was to evaluate the effectiveness of PBM in the process of bone remodeling in dentistry using randomized controlled trials. Initially, a total of 1,011 articles published from January 2008 to December 2021 were retrieved from five electronic databases (PubMed, Scopus, Cochrane Library, EMBASE, and CINAHL). After a two-step review, nine articles met the inclusion criteria. The parameter of PBM, group, treatment sessions, assessment times and outcomes of the included studies were reviewed. Eighty-nine percent of the studies revealed positive effects on bone formation between the laser group and the control group. Only one article reported that light-emitting diode did not significantly enhance osteogenesis. Additionally, the present study shows that Gallium aluminum arsenide of near infrared (NIR) laser with continuous mode is the most commonly used form of PBM. The biostimulatory effects are dependent on several parameters, with wavelength and dose being more important than others. Based on this review, it is suggested that the NIR range and an appropriate dose of PBM could be used to increase the efficiency of stimulating bone healing and remodeling. However, standardization of treatment protocols is needed to clarify therapeutic strategies in dentistry.

Carbon dioxide laser therapy for the management of genitourinary syndrome of menopause: A meta‑analysis of randomized controlled trials.

Genitourinary symptoms of menopause (GSM) affect ~50% of women after menopause. Recently, CO2 laser therapy has been used for managing GSM but without high quality evidence. The present review assessed the effectiveness of CO2 laser therapy in the management of GSM. PubMed, Embase, Web of Science, CENTRAL and Scopus databases were searched for randomized controlled trials (RCTs), published up to June 30, 2023, comparing CO2 laser and sham laser treatments for GSM management. The outcomes of interest included Female Sexual Function Index (FSFI), Vaginal Health Index (VHI) and visual analog scale (VAS) for dyspareunia, dryness, burning, itching and dysuria. A total of seven RCTs were included in the review and meta-analysis, with 6/7 studies using three sessions of laser therapy, 4-8 weeks apart. Meta-analysis demonstrated no statistically significant difference in FSFI [mean difference (MD), -1.48; 95% CI, -5.85, 2.89; I2=45%] and VHI scores (MD, -0.18; 95% CI, -1.66, 1.31; I2 =72%) between laser and control groups. Meta-analysis also demonstrated no statistically significant difference in VAS scores for dyspareunia (MD, -1.63; 95% CI; -4.06, 0.80; I2=91%), dryness (MD, -1.30; 95% CI, -3.14, 0.53; I2=75%), burning (MD, -0.76; 95% CI, -2.03; 0.51 I2=56%), itching (MD, -0.28; 95% CI, -0.95, 0.38; I2=0%) and dysuria (MD, 0.15; 95% CI, -0.37, 0.67; I2=23%) between the groups. The included RCTs had low risk of bias. In conclusion, meta-analyses of high-quality sham-controlled RCTs indicated that CO2 may not have any beneficial effect on GSM. Limited data and high heterogeneity in meta-analyses in this area of research are important limitations that need to be addressed by future RCTs.

Comparative evaluation on the effect of different cavity disinfectant nano gels; Chlorohexidine, Propolis, Liquorice versus Diode Laser in terms of composite microleakage (comparative in vitro study)

IntroductionThe application of different cavity disinfectants is an essential step that eliminates bacteria after cavity preparation. However, some of these materials may affect restoration sealing ability.AimThis study aimed to assess the degree of microleakage at the tooth restoration interface after using different nano prepared cavity disinfectants versus Diode Laser.Materials and methodsThree disinfectants were prepared on the nanoscale; Propolis, Liquorice and Chlorhexidine. A total of 40 extracted premolars with standard class V cavities were prepared on the facial surface. Teeth were divided into five groups according to the applied cavity disinfection protocol; no treatment, Chloehexidine, Propolis, Liquorice, and Diode Laser. After application of composite resin restoration, all teeth were subjected to thermocycling, afterwords the degree of microleakage was measured in micrometers. Data were analyzed by one-way analysis of variance (ANOVA) test, followed by Bonferroni’s and Tukey’s post hoc test.ResultsThe highest mean microlekage value was recorded in no treatment group, followed by Liquorice, Propolis. While Diode Laser group showed the lowest degree of microleakage.ConclusionDiode Laser cavity disinfectant has no negative effect on the restoration sealing ability. Nano prepared Propolis showed comparative results to nanoChloehexidine as both had low degree of microleakage.

Efficacy of different remineralizing agents on primary teeth exposed to therapeutic gamma radiation: An in vitro randomized control study

BackgroundTherapeutic radiation-induced caries is a major side effect. Dental and oral heath are adversely affected by the direct effects of radiotherapy. Preventive procedures are preferred to reinforce dental tissue resistance against radiation damage. ObjectiveResearch aim is to test the impact of different remineralizing protocols on the mineral content of deciduous enamel exposed to a therapeutic dose of gamma radiation. MethodsThirty deciduous enamel specimens were divided randomly into three experimental categories based on the type of remineralizing agent used. Group I (gamma irradiated teeth, then painted with fluoride varnish), Group II (gamma irradiated teeth, then treated with bioactive glass) and Group III (gamma irradiated teeth, and then treated with a diode laser 980 nm). Prepared specimens were assessed for mineral content by environmental Energy Dispersive X-ray Analysis. SEM photomicrographs were performed simultaneously. Results were investigated concerning pre- and post-irradiation values difference. The paired-samples t-test was performed to compare the atomic and weight percentages of the selected elements obtained from the samples in the control groups before and after therapeutic radiation. One-way analysis of variance and post hoc Tukey tests were used to compare between the categories regarding weight and atomic percentages. ResultsCalcium/Phosphorus (Ca/P) ratio and Fluoride content decreased significantly after radiotherapy. Fluoride content significantly increased after remineralizing agents' application with the greatest increase in Bioactive glass group followed by fluoride varnish (F.varnish) group and the least increase was in diode laser group. Significant increase in Ca/P ratio in bioactive glass group followed by insignificant increase in F.varnish group (I) with the least increase noticed in the Diode laser group. ConclusionTherapeutic radiation caused marked decrease in enamel mineral content. However, the reminralizing agents applied have an improving effect on the caused damage.

Ceramic Bond Strength of Various Metal Substrate Using Traditional and Digital Methods

Purpose: The aim of this study was to investigate the bond strength of cobalt-chromium (Co-Cr) metal frameworks prepared with three different production techniques with dental porcelain. Methods: In this study, a total of thirty disc samples divided to Three groups (n = 10/group) of metal cylinders (10 mm diameter x 4mm thickness with ring base (12 mm diameter x 1mm thickness) were fabricated by casting (Co–Cr), CAD CAM milling blank(Co–Cr) and by selective laser sintering SLM (Co–Cr) and abraded with airborne-particles then feldespathic porcelain was applied for all discs (10mm diameter x 2mm thickness), before the shear bond strength (SBS) test, the Surface characteristics of the dental alloys were observed by scanning electron microscopy (SEM) to determine the thickness of the oxide layer then surface roughness tester using TR220 portable roughness tester The average surface roughness (Ra) was determined for each group. SBS test-values and failure modes were recorded. Data were analyzed using ANOVA, Tukey’s HSD (a = 0.05). Result: no statistically significant difference of the metal-ceramic bond strength of the test roughness used between casting, milling, and laser no statistically significant difference of the metal-ceramic bond strength of the SBS test between casting compare with milling, and laser groups SBS test statistically significant difference of the metal-ceramic bond strength of the test between milling, and laser technique. The mode of failure shows was mainly cohesive and mixed for all specimens. Conclusion: Within the scope of this research, the CAD/CAM milling Co-Cr alloy has a shear bond strength comparable to the castable alloy. For metal-ceramic restorations, the CAD/CAM milling Co-Cr alloy is an alternative to the castable alloy. Co-

Laser Therapy for Vulvar Lichen Sclerosus, a Systematic Review.

Lichen sclerosus (LS) is a chronic inflammatory disease that mainly affects the anogenital area, with a higher incidence in post-menopausal women. In the long term, it can lead to loss of vulvar architecture or progress to squamous cell carcinoma. The evidence-based treatment involves high-potency topical corticosteroids in long regimens. However, second-line treatments are not well-established, including laser therapy. This current study aims to assess the level of evidence supporting this therapy. We conducted a search for primary-level studies published before April 2023 through MEDLINE/PubMed, Embase, Web of Science, Scopus, and CENTRAL, with no restrictions on the publication language or date. The methodological quality and risk of bias of the included studies were evaluated using the updated Cochrane Collaboration's tool for assessing risk of bias (RoB-2). Six studies (177 patients) met our eligibility criteria. Laser therapy was compared to topical corticosteroid treatment in five out of six studies. No significant histological differences were found, except for an increase in collagen production in the laser group. A greater reduction in itching, pain, and dyspareunia at 1 and 3 months of treatment in the laser group, as well as in the Skindex-29 at 6 months, was reported. Patient satisfaction was significantly higher among those who received laser therapy. Tolerability was excellent. No significant differences were observed in any of the previous aspects in the study compared to the placebo. In conclusion, there is not enough evidence to recommend laser therapy as a standalone treatment.

Clinical and radiographic evaluation of low-level laser therapy in primary teeth pulpotomy treatment: a randomized clinical trial

Aim. The aim of this study was to compare the effectiveness of diode laser and low-level laser therapy (LLLT) in primary pulpotomy treatments with deep dentinal caries. Materials and methods. The study comprised 90 patients (42 females and 48 males) aged 6–9 years with deep dentin caries in the lower second molar. The patients were assigned to the following treatment groups: the diode laser group (n^S= 45) or the LLLT group (n^S= 45). The appointments were scheduled 3, 6, and 12 months after the treatment, and both clinical and radiographic follow-ups were performed. Results. The diode laser group had a clinical success rate of 95.6% and a radiological success rate of 93.3% at 12 months, while the LLLT group had a clinical success rate of 97.7% and a radiological success rate of 90.9%. There were no statistically significant differences in the success rates of the two groups. Conclusions. LLLT+CH may be a good treatment alternative for pulpotomy instead of devital diode laser pulpotomy.

Evaluation of a low-level laser protocol for the control of postoperative pain, trismus, and edema in retained third molar surgeries

This split mouth double-blind randomized trial was aimed to evaluate the effect of low‑level laser therapy (LLLT) on pain, trismus, and swelling used in the postoperative period of surgery of third molars retained. Fifteen patients with symmetrically impacted mandibular third molars were randomized in two groups: LLLT group received only single‑dose intraoral and extraoral immediately after surgery; another group, received LLLT placebo on the other side. They were evaluated on the second and seventh days after surgery, the pain was evaluated in the first day too. There was no statistical difference in trismus, edema and pain between groups when examining data in the postoperative period of one, two or seven days. The pain level was significantly lower from the first day to seventh day in both groups. The laser group presented a delay or decreasing use of analgesics in the first postoperative day. Despite the statistically insignificant difference results, clinically it has been observed improvement of symptoms of discomfort related by patients. The results suggest that further studies are necessary for protocols consolidation and suggest explore combinations of photodynamic therapies.

Surface Roughness of Er, Cr: YSGG Laser Etched Enamel Compared to Acid Etching: An In Vitro Study

Objectives: Erbium-based lasers have been used in dentistry with different parameters for enamel conditioning with controversial results on the optimum parameter. This study aims to compare the surface roughness of enamel after conditioning by erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser or 37% phosphoric acid and after remineralization, using a scanning electron microscope (SEM). Materials and Methods: Forty-five extracted premolars for orthodontic purposes were divided into three groups according to the conditioning technique. Group 1 conditioning by Er, Cr: YSGG laser 4.5 watts/30 Hz, Group 2 conditioning by Er, Cr: YSGG laser 4.5 watts/ 20 Hz, and Group 3 conditioning by 37% phosphoric acid. Surface roughness was measured using SEM after conditioning and after remineralization using Recaldent GC MI Paste Plus. Statistical analysis was done by one-way analysis of variance ANOVA test used to compare between groups, followed by Tukey’s post hoc test. Results: Enamel surface conditioned by Er, Cr: YSGG 4.5 watts/20 Hz laser had significantly less surface roughness than 37% phosphoric acid conditioned. After remineralization both the laser groups produced significantly lower surface roughness compared to acid conditioning. Conclusion: Er, Cr: YSGG laser conditioning of enamel surfaces (with 4.5 watts and 20 Hz/ 30 Hz frequency) produced less surface roughness which could be used as a promising alternative for acid conditioning. Clinical Relevance: laser conditioning of enamel using Er, Cr: YSGG with 4.5 watts could be a promising alternative for acid conditioning since it produces less surface roughness, less plaque accumulation on the surface, and less bacterial adhesion.

The Effect Of Er,Cr:YSGG Laser Conditioning on Dentin Bond Strength and Nanoleakage of Universal Adhesive Systems: An In Vitro Study.

To investigate the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser conditioning on dentin bond strength and nanoleakage of different universal and self-etch adhesives. A total of 84 intact human third molar teeth were cut at the dentin level, and half of them were laser conditioned. The specimens were divided into three groups; two different universal resins and one self-etch adhesive resin were applied and composite resin restorations were created. For the microtensile bond strength (µTBS) test, 20 microspecimens were prepared from the laser and control group of each adhesive (n = 20) and tested with a universal device. For nanoleakage observation, 10 specimens were prepared from each group (n = 10) and stored in silver nitrate solution, and then the amount of nanoleakage was analyzed by field emission scanning electron microscopy (FESEM). Data were analyzed with two-way ANOVA, Tukey's honestly significant difference, and chi-square tests. The mean dentin bond strength of all adhesives in the laser groups was found to be statistically significantly lower than those of the control groups (P < .05). No difference was found between the mean bond strength of the adhesives in the laser and control groups (P > .05). Higher nanoleakage was observed in all adhesives in the laser groups compared to the control groups (P < .05). Irradiation of the dentin surface with Er,Cr:YSGG could adversely affect the µTBS and nanoleakage, likely by affecting the structure of the hybrid layer.

Assessment of clinical outcomes and patient response to gingival depigmentation using a scalpel, ceramic bur, and diode laser 980 nm

ObjectiveThis research compares the clinical outcomes of gingival depigmentation procedures with conventional scalpel, ceramic trimmer bur, and diode laser techniques.Materials and methodsTwenty-four individuals with physiologic gingival hyperpigmentation received random allocation to one of three treatment groups: scalpel, ceramic bur, or diode laser. Pain score, operation time, bleeding index, degree of epithelialization, wound healing, Dummett-Gupta Oral Pigmentation Index (DOPI), and Takashi Index score changes were all investigated at different time points.ResultsAt 12-h follow-up, significant variations in pain scores were seen between the laser and scalpel groups (p = 0.003) but not between the laser and ceramic bur groups. The diode laser group completed the procedure significantly quicker than the scalpel and ceramic bur groups (p = 0.004 and p = 0.001, respectively). The ceramic trimmer bur and diode laser groups showed significantly less bleeding tendency than the scalpel group. Wound healing and the degree of epithelialization were similar in all groups. DOPI and Takashi indices significantly decreased compared to baseline in all groups, with no significant difference recorded between all groups.ConclusionWhile diode lasers are a safe and effective treatment option for gingival hyperpigmentation, providing optimal aesthetics with reduced discomfort to patients, a ceramic trimmer bur can also be used as a simple and affordable alternative to a laser in gingival depigmentation procedures.Clinical relevanceGingival hyperpigmentation is a major aesthetic issue for many individuals. Laser and ceramic trimmer bur treatments produce equivalent aesthetic outcomes for gingival hyperpigmentation.

Comparison of freehand technique and a novel laser-guiding navigation system in femoral neck-cannulated screw fixation: a randomized controlled trial

Cannulated screw fixation is essential in treating femoral neck fractures, and the widely used freehand technique has several limitations. Therefore, we designed a new laser-positioning and navigation system and compared its efficacy with that of the traditional freehand technique in the cannulated screw fixation of femoral neck fractures. This randomized controlled single-blind trial recruited patients with femoral neck fracture, who were treated using either the newly designed laser-navigation device or the freehand technique. In in-vitro experiments, using the femoral neck model, the laser group was better than the freehand group in terms of operation time (P = 0.0153) and radiation exposure time (P < 0.001). In in-vivo experiments, involving 30 patients (15 in each group), the laser group was better than the freehand group in terms of operation time (P < 0.001), radiation exposure time (P < 0.001), blood loss (P < 0.001) and first success rate (P = 0.03). There was no difference in visual analog scale score, Harris score, and fracture-healing time between the two groups. In conclusion, the novel laser-guiding navigation system resulted in shorter operation time, less radiation exposure, and higher first success rate compared with the freehand technique. Further qualified investigations with a larger number of patients and longer follow-up are required in the future.

Enhanced bone healing of photothermal hydrogel via mild heat stimulation and Zn2+ release

The loss of alveolar bone has caused heavy burden worldwide. In this paper, we have synthesized photothermal hydrogel with sustained release of Zn2+ and repeated mild heat stimulation. The in situ retention of ZnO microspheres (ZnO-MPs) and polydopamine (pDA) have been achieved by loading into the thermosensitive hydrogel network after injection in the subcutaneous tissue. The hydrogel could reach around 42 °C under near infrared light irradiation (for 6 min). And after 2, 4 and 6 days, the in situ hydrogel was proved still photothermal sensitive. Sustained released Zn2+ and mild heat (for 6 min each) promoted BMSCs cell viability and osteogenic differentiation, and after being implanted into the tooth socket after 14 days, micro-CT, HE and masson staining have illustrated that more newly formed bone tissue was observed in the hydrogel + laser group, compared with that of control. This photothermal hydrogel has demonstrated efficient photothermal effects, drug releasing capacity with promising clinical application potential for bone regeneration in the future.

The Effect of 10% Sodium Ascorbate and Er: YAG Laser on the Microtensile Bond Strength of Composite Resin to Bleached Enamel

Background: There are various methods proposed to prevent the reduction of substrate micro tensile bond strength to bleached enamel. Therefore, this study aims to evaluate and compare the effectiveness of two common methods, namely 10% sodium ascorbate and Er:YAG laser irradiation, in increasing the microtensile bond strength of composite resins to bleached enamel. Methods: In this in vitro study, 72 maxillary premolar teeth were divided into four equal groups: bleached control group, unbleached control group, treated with 10% sodium ascorbate, and Er:YAG laser-treated group (60 mJ, frequency = 10 Hz, and power of 0.6 W with a 400-µm diameter tip). The samples were cut by a CNC cutting machine for a microtensile bond strength test. Results: The Er:YAG laser group showed the highest mean bond strength (27.3 MPa), while the bleached control group had the lowest (15.06 Mpa). There was a significant difference between the bleached and unbleached control groups (P&lt;0.001). Samples prepared with 10% sodium ascorbate and the Er:YAG group had higher tensile bond strength than the bleached control group (P&lt;0.0001). Tensile bond strengths were not significantly different between the 10% sodium ascorbate and the Er:YAG laser preparation groups (P=0.361). Conclusion: The findings of this study indicate that the microtensile bond strength of composite resins to bleached enamel can be increased by 10% sodium ascorbate and Er:YAG laser irradiation.

The Effect of Various Lasers on the Bond Strength Between Orthodontic Brackets and Dental Ceramics: A Systematic Review and Meta-Analysis.

Background/objective: This systematic review and meta-analysis aimed to assess how laser conditioning affected brackets bonded to dental ceramics' shear bond strength (SBS). Materials and methods: The study was conducted by searching Pubmed/Medline, Scopus, Embase, Web of Science, the Cochrane Library, and Google Scholar up to September 14, 2022. In addition, the reference lists of the relevant articles were checked manually. Articles that compared SBS of laser-treated feldspathic, lithium disilicate, or zirconia surfaces with other standard techniques for bonding metal or ceramic orthodontic brackets were considered. Using a random-effects model, data pooling was carried out as the weighted mean difference (WMD). Results: This study initially contained 1717 reports, and following review, 32 articles were deemed suitable for our meta-analysis. The pooling results showed that the treatments with lasers such as "Er:YAG" [WMD = -1.12 MPa; 95% confidence interval (CI): -1.93 to -0.31], "Er:YAG + Silane" (WMD = -3.08 MPa; 95% CI: -4.77 to -1.40), and "Nd: YAG + Silane" (WMD = -2.58 MPa; 95% CI: -3.76 to -1.40) had statistically significant lower adhesion values compared with controls. Contrarily, "Ti:Sapphire femtosecond" demonstrated significantly higher bonding values (WMD = 0.94 MPa; 95% CI: 0.29-1.60). In contrast, other interventions obtained no statistically significant difference in SBS. Conclusions: Most of the laser groups showed results comparable with those of conventional approaches. Although more research is necessary for definitive conclusions, laser treatment may be an effective option for treating the surfaces of ceramic materials.

Efficacy of photobiomodulation in the treatment of oral mucositis in patients undergoing antineoplastic therapy: systematic review and meta-analysis.

To evaluate the effectiveness of photobiomodulation in the treatment of oral mucositis. Systematic review and meta-analysis encompassing in the electronic databases: LILACS, MEDLINE, EMBASE, COCHRANE, SCOPUS, WEB OF SCIENCE, and CINAHL and in http://clinicaltrials.gov . Eligibility criteria were randomized, non-randomized, and observational studies that used photobiomodulation for the treatment of oral mucositis. The endpoints were reduction in the severity of oral mucositis, duration of lesions, and pain reduction. For data analysis, the Review Manager 5.4 program was used. A total of 316 studies were identified, 297 in the electronic databases and 19 in http://clinicaltrials.gov . After removing duplicates, 260 studies were selected for title and abstract reading, of which 223 were excluded. A total of 37 studies were chosen for full reading, of which 6 were included in the review, totaling 299 patients. The treatment used was photobiomodulation. The patients were divided into two groups: the laser group used only photobiomodulation or associated with other therapies, and the control group did not use photobiomodulation. For the endpoint reduction in the severity of oral mucositis (OM), the chance of reduction of the OM was greater in the laser group as compared to the control group. For the endpoints duration of OM lesions and pain reduction, it was not possible to carry out a meta-analysis due to the high heterogeneity between studies. In the interpretation of the meta-analysis, the reduction in the severity of oral mucositis was greater in the group that received photobiomodulation. Photobiomodulation was effective in the treatment of oral mucositis.

Anti-infective Efficacy of Mechanical Debridement with Adjunctive Modalities on Clinical and Cytokine Parameters in Treatment of Chronic Periodontitis: Randomized Controlled Clinical Trial.

Periodontal debridement involves conventional scaling and root planing (SRP) along with variant forms of adjunctive therapies. In the present clinical trial, we investigated if the adjunctive use of HybenX gel or diode laser along with SRP could provide a favorable outcome for the treatment of chronic periodontitis. The present study involved 60 subjects diagnosed with chronic periodontitis who were randomly assigned as test groups (laser or HybenX) or control group (SRP alone). The primary outcomes of the clinical trial were pocket probing depth (PPD) and clinical attachment level (CAL), which was evaluated at baseline and at third-month time interval. Additionally, secondary outcomes included estimation of reduction in inflammatory mediators interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) in gingival crevicular fluid using enzyme-linked immunosorbent assay at baseline and third-month intervals. Normality determination was checked using Shapiro-Wilk test. Since the data was not normally distributed, nonparametric tests were applied. The comparison of clinical parameters between the groups was analyzed with Kruskal-Wallis test. Wilcoxon sign rank test was used to compare the pairwise comparison of clinical parameters among the groups from baseline to third-month follow-up. The inflammatory mediators at various time points were compared using a One-way analysis of variance test, and the inflammatory mediators in each study group were compared using a paired t-test. Both the test groups demonstrated a decrease in PPD and CAL. However, the HybenX group exhibited statistically significant reduction at the end of the third-month study interval compared to the laser group and SRP alone. Further, the secondary outcome IL-1β and TNF-α analysis exhibited statistically significant reduction in all the groups posttherapy. The adjunctive application of HybenX gel yielded an advantage compared to laser and SRP for the treatment of chronic periodontitis. Adjunctive use of the oral tissue desiccant (HybenX gel) combined with SRP improved the periodontal pocket disinfection process and enhanced tissue healing devoid of adverse effects.

Long-term longitudinal retinal changes after conventional and pattern scan laser panretinal photocoagulation in diabetic retinopathy

PurposeComparison the effect of conventional and pattern scan laser (PASCAL) panretinal photocoagulation (PRP) on macula and optic disk in diabetic retinopathy (DR). MethodsThis retrospective study included 57 patients. In the conventional laser group, PRP was completed using the LightMed LightLas 532 laser device in accordance with the ETDRS protocol. In the pattern laser group, it was completed in a single session using PASCAL device with 20 ms pulse duration and multispot pattern. Central macular thickness (CMT) and retinal nerve fiber layer (RNFL) thickness were evaluated before laser treatment and at 1, 6 and 12 months after treatment. ResultsThere were 30 eyes in the conventional laser group and 27 eyes in the PASCAL group. There was no significant difference between the groups in terms of age (p = 0.560), sex (p = 0.866), duration (p = 0.498) and stage (p = 0.503) of diabetes, visual acuity (p = 0.104) and intraocular pressure (p = 0.963).In both groups, CMT increased significantly (p ˂0.001), while RNFL thickness decreased significantly (p ˂0.001) at 12 months. While CMT and mean RNFL thickness increased in the first month in both groups, it decreased progressively until the 12th month. ConclusionConventional and pattern laser systems used in the treatment of DR................ cause an increase in CMT and thinning of RNFL thickness in the long term. This change is more in the conventional laser group compared to the pattern laser.

The Effect of Femtosecond Laser Surface Patterns on the Effectiveness of Resin Composite to Zirconia Bonding.

This laboratory study aimed to evaluate the effect of different surface patterns using femtosecond laser treatment on the enclosed mold shear bond strength (EM-SBS) of resin composite to zirconia (ZrO2) surfaces and to contrast it with the widely used tribochemical silica coating (TBC) surface conditioning method. A set of fifteen rectangular ZrO2 blocks were randomly divided into five groups according to surface pretreatment: Control G0-no treatment; G1-TBC with silane application; G2-femtosecond laser irradiation with horizontal lines 30 µm apart; G3-femtosecond laser irradiation with horizontal lines 15 µm apart; and G4-femtosecond laser irradiation with cross lines 30 µm apart. The pretreated surfaces were characterized by a surface profilometer, tensiometer and scanning electron microscope. The EM-SBS of resin composite stubs to ZrO2 was measured followed by fractographic analysis. The surface roughness and water contact angle were observed to be statistically higher among the femtosecond laser groups compared to the TBC and control groups. The G4 group exhibited the highest EM-SBS among all the groups, irrespective of the ageing conditions used. At the end of 5000 thermocycles, G4 exhibited EM-SBS of 14.05 ± 4.21 MPa compared to 13.80 ± 3.01 MPa in G1 and 5.47 ± 0.97 MPa in G0. The two-way ANOVA revealed a significant effect of both study groups and ageing conditions on the EM-SBS (p < 0.001). Utilization of femtosecond laser technology holds promise as a potential and alternative mechanical retention approach for enhancing the bonding strength of the resin composite to ZrO2.

Evaluation of the relationship between metallurgical properties and metal-ceramic bond characteristics of Co-Cr alloys manufactured by different techniques

Metal-ceramic restorations made from cobalt chromium (Co-Cr) alloy have been increasing, but studies on the effects of different manufacturing techniques on metal-ceramic interface characteristics and metal-ceramic bond strength are sparse. The purpose of this in vitro study was to examine the metal-ceramic interface and the metal-ceramic bond strength of a Co-Cr alloy produced by casting, milling, and selective laser melting (SLM) with or without thermal cycling. Co-Cr alloys were prepared by casting, milling, and SLM. Two different SLM devices were used. Ninety-six specimens (25×3×0.5mm) were manufactured. The structure of the oxidation surface of Co-Cr specimens was examined by scanning electron microscopy (SEM) and by X-ray fluorescence spectroscopy (XRFS). After porcelain application, selected specimens were thermal cycled, and the strength of the metal-ceramic bond was measured by the 3-point bend test. All specimens were analyzed for failure type with a stereomicroscope. The elemental composition and morphology of the metal-ceramic interface were examined by XRFS and SEM with energy-dispersive X-ray (EDX). The results of bond strength were analyzed using a 2-way analysis of variance (ANOVA) for manufacturing methods and testing conditions and the Tukey honest significant difference (HSD) test (α=.05). The main effect of the interactions of the testing condition and manufacturing method variables on the bond strength variable was not statistically significantly different. No significant differences were found among the testing conditions tested (P=.638). Significant differences were found among the manufacturing methods tested statistically (P<.001). Statistically significant differences were found in the CAD-CAM and CONSEPT LASER groups, the CAD-CAM and SLM LASER groups, the CAD-CAM and CAST groups, and the CAST-SLM LASER groups (P<.05). Differences were observed among the interface morphologies of casting, milling, and the two SLM groups. The bond strength between Co-Cr alloy and ceramic is affected by the manufacturing method. The metal-ceramic bond strength is independent of thermal cycling. The bond strength value in all groups was over 25MPa, which has been considered clinically acceptable. The interface metallurgical structures of Co-Cr alloys were affected by different manufacturing techniques.