Light Curing Research Articles

The Potential of Silver Diamine Fluoride in Non-Operative Management of Dental Caries in Primary Teeth: A Systematic Review

Background and Objectives: Dental caries has seen an increase in untreated cases, leading to significant health and quality-of-life impacts, necessitating innovative approaches like the promising non-operative management with silver diamine fluoride. This study aimed to evaluate the mechanisms of action of silver diamine fluoride on arresting dental caries in primary teeth. Materials and Methods: A systematic search was conducted across MEDLINE (PubMed), Google Scholar, and Wiley Online Library, including both in vivo and in vitro studies published from 1 January 2017 to 16 October 2022. The Cochrane Risk of Bias Tool assessed bias in in vivo studies, while the Quality Assessment Tool for In Vitro Studies evaluated the methodological quality of in vitro studies. Results: Nineteen publications met the inclusion criteria. Two studies indicated that silver diamine fluoride application significantly alters oral microflora, contributing to caries arrest. Additionally, two studies reported increased mineral density and mineral content in demineralised primary teeth, emphasising silver diamine fluoride’s role in promoting remineralisation. Three studies demonstrated significant improvements in surface microhardness, enhancing tooth resistance. However, no significant qualitative changes in bacterial species composition were noted. Modified silver diamine fluoride application techniques, including light curing or laser irradiation, enhanced efficacy, with light curing notably increasing surface microhardness. Based on a limited number of studies, no statistically significant differences in clinical effectiveness were observed with higher silver diamine fluoride concentrations or extended application durations. Conclusions: Silver diamine fluoride effectively induces quantitative changes in oral microflora and enhances the microhardness and mineral density of enamel and dentine in primary teeth, with modified application methods showing potential for improved outcomes.

In Vitro Testing of Protective Eye Wear in Blocking Blue Light from Dental Light Curing Unit

Aim: To evaluate the ef?cacy of wearing protective eyewear in preventing harmful Dental light-curing units (LCUs). Background: Dental light-curing units generate blue light, capable of inducing soft-tissue burns and ocular harm like retinal damage. The intensity of blue light emitted by dental Light Curing Units is substantially higher, thereby potentially constituting a significant "blue light hazard." Material and Methods: To study the effect of protective glasses, reverse methodology was followed as the effect of blue light on the eye is difficult to measure; Circular composite disc samples were grouped into two, one of which was polymerized directly while the other had protective glass in between, Fourier transform infrared spectroscopy (FTIR) analysis was done and the degree of conversion was calculated. Results: Data obtained were analysed using One Way ANOVA. The mean values for "Degree of Conversion" in Group I (Without Protective Glass) is 1.334 +512 and for Group II (with protective glass) is -2.623 + 1.544 .One Way ANOVA revealed statistically significant difference between Group I and Group II (p=0.000) Conclusion: Within the limitations of this in vitro study, it can be concluded that the protective glasses are successful in filtering the harmful blue light emitted by LCU and should be used in day-to-day practice to improve the amount of light they deliver to the restoration from the LCU and prevent any harm to the ocular tissues. Clinical implications: Blue light filtering glasses in a dental operatory provide optimum protection, and the operator can safely watch and improve the amount of light delivered to the restoration from the LCU.

Effect of Surface Treatments on Shear-bond Strength of Glass Ionomer Cements to Silver Diamine Fluoride-treated Simulated Carious Dentin.

This study investigated the effect of different surface treatments on the shear bond strength (SBS) and failure modes of self-cured (SC) and light-cured (LC) high-viscosity glass ionomer cements (HVGICs) to silver diamine fluoride (SDF)-treated simulated carious dentin (SCD). Extracted human premolars were sectioned and pH cycled for 10 days to simulate carious dentin. The demineralized specimens were treated with 38% SDF (Riva Star) for 2 minutes, washed, stored in deionized distilled water at 37°C for 2 weeks, and subjected to the following surface treatments (n=14): T1 - no treatment (control); T2 - 10 seconds polyacrylic acid (PAA); T3 - 5 seconds phosphoric acid (PPA); T4 - 5 seconds PPA plus universal adhesive (Zipbond); and T5 - 5 seconds PPA plus resin-modified GIC adhesive (Riva bond LC). SC (Riva Self-cure HV) and LC (Riva Light-cure HV) HVGICs were applied to the conditioned specimens and stored in artificial saliva at 37°C for 1 week. SBS and failure modes were subsequently determined. Statistical analyses were performed using Kruskal-Wallis/post-hoc Mann-Whitney U and Chi-square tests (α=0.05). The highest SBS was observed when SC and LC were restored with T2 and T5, respectively. Significant differences in SBS were as follows: SC - T2, T1 > T5, T3; LC - T5, T4, T3 > T2. SC generally exhibited adhesive failures, while LC presented both adhesive and mixed failures. The preferred method for preparing SDF-treated carious dentin before restoration application is PAA for SC and PPA plus RMGIC adhesive for LC HVGICs.

Elemental analysis and micromorphological patterns of tooth/restoration interface of three ion-releasing class V restorations

ObjectivesTo evaluate and compare the ion-releasing capability of three different restorative systems at the restoration/tooth interface elemental analysis using energy-dispersive X-ray technique. Additionally, micromorphological patterns of the restoration/tooth interfaces was investigated.Materials and methodsEighteen freshly extracted sound human premolars were collected for the study. The premolars were randomly assigned into 3 groups (n = 6) based on the type of restorative materials used: Giomer (Beautifill II), ion-releasing composite (Activa Presto), and RMGI (Riva Light Cure). Half of the specimens in each group were tested after 24 h (the “immediate group”), while the remaining half were tested after 6 months of storage in deionized water (the “delayed group”). Standardized box-shaped cavities along the cervical area of teeth crowns and restored them with the assigned restorative material following manufacturers’ instructions. The specimens were sectioned buccolingually into 2 halves. One half of each specimen was subjected to elemental analysis using energy-dispersive X-ray technique (EDX), while the remaining half was sputter coated and underwent micromorphological analysis of the restoration/tooth interface using a scanning electron microscope (SEM). The collected data from elemental analysis test were tabulated and subjected to statistical analysis.ResultsThe two-way ANOVA test showed significant differences in both phosphorus and calcium levels among the tested restorative systems (p < 0.05). In the immediate subgroup, RMGI recorded the highest phosphorus level (0.1527), followed by the ion-releasing composite (0.1172), while Giomer exhibited the least levels (0.0326) (p < 0.05). The ion-releasing composite group had the highest calcium level (0.2797), followed by RMGI (0.248), and Giomer (0.2385) respectively (p < 0.05). In the delayed subgroups, Giomer recorded the highest phosphorus level (0.1526), followed by the ion-releasing composite (0.1058), and RMGI group (0.0466) respectively (p < 0.05). RMGI had the highest calcium level (0.2801), followed by the ion-releasing composite (0.2659), and Giomer had the lowest level (0.1792) (p < 0.05). The micromorphological analysis of the restoration/tooth interfaces showed good adaptation between the composite and tooth substrate in different restorative groups.ConclusionsThe ion-releasing capability of the three restorative systems appears to be comparable. The rate of mineral release and diffusion is affected by time and composition.

Effect of Battery Level During Successive Charging Cycles on the Performance of Certified and Low-cost Uncertified Light-curing Units Available on E-commerce.

To evaluate the influence of battery level on power (mW), emission spectrum (mW/cm2/ nm), and light distribution on the active tip (mW/ cm2) of certified (FDA/ANVISA) and low-cost uncertified light-curing units (LCUs) purchased through e-commerce. Seven LCUs, three certified: VALO Grand (Ultradent); Radii Xpert (SDI); and LED.B (Woodpecker); and four uncertified: 1 Sec; BS 300; LED curing light; and VAFU (VRN, AZDENT), were used. The LCUs were evaluated by calculating the power (mW) after each sequential five exposure cycles of 20 seconds and the emission spectrum (mW/cm2/nm) in the initial and final cycles, using an integrating sphere during three battery charging cycles. Beam profiling was used to check the light distribution on the LCU tip after every 50 exposure cycles until the battery fully discharged. Data were analyzed by linear regression between power and the number of exposure times (R2). The certified LCUs VALO Grand (R2=0.005), LED.B (R2=0.02), and Radii Xpert (R2=0.09) and the uncertified LCU VAFU (R2=0.002) had no significant power reduction during the three battery charging cycles. The uncertified LCUs BS 300 (R2=0.87), 1 Sec (R2=0.60), and LED curing light (R2=0.83) showed significant power reduction, decreasing the emission spectrum (mW/cm2/nm) at the end of the battery charging cycle. The light distribution on the active tip across the level battery was modified significantly with successive exposure times. The certified LCUs (VALO Grand, Radii Xpert, and LED.B) and uncertified LCU (VAFU), maintained power, emission spectrum, and light distributions during the tested battery life cycles. Low-cost certified LCU LED.B exhibited inhomogeneous light concentrated at the center of the tip. Low-cost uncertified LCUs-BS 300, 1 Sec, and LED curing light-had significant power reductions during the battery cycles and increased inhomogeneous light distribution along the successive exposure times.

Effect of double adhesive layer application on micro-tensile dentin bond strength of a universal adhesive

IntroductionAchieving optimal dentin bond strength is crucial for the long-term success of adhesive restorations. This study aims to evaluate the impact of double adhesive layer application, with and without light curing between applications, on the micro-tensile dentin bond strength (µ-TBS) of a universal adhesive, in comparison to the conventional single-layer application.MethodsIntact human molars were divided into three groups (n = 15) according to the adhesive application technique using a universal self-etch adhesive (Tetric N-Bond Universal, Ivoclar) as follows: (1) according to the manufacturer's instructions, (2) double-layer application without light curing between layers, and (3) double-layer application with light curing between layers. Samples were immediately tested for µ-TBS, with failure types recorded as adhesive, cohesive, or mixed. Representative samples were observed by scanning electron microscopy. Data were analyzed using multiple-way ANOVA (α = 0.05).ResultsThe double adhesive layer with and without light curing between layers showed similar μ-TBS to that of the control group (p &amp;gt; 0.05).DiscussionFrom a clinical perspective, these findings suggest that the accurate application of a single layer of a universal adhesive can be as effective as more complex techniques. Additionally, the use of universal bonding agents may have contributed to the outcomes observed in this study. In conclusion, double adhesive layer application and light curing between adhesive layers did not increase the µ-TBS with the universal adhesive agent explored.

Effects of curing lights on polymerization shrinkage of composite attachments in clear aligner treatment: A microcomputed tomography study

This study aimed to investigate the polymerization shrinkage of composite attachments and changes in attachment templates during bonding in clear aligner treatments. A total of 24 extracted teeth were divided into 4 groups, and plaster models were digitized. Attachment templates were produced with beveled attachments on premolars and rectangular attachments on molars. Polymerizations used a halogen curing light (800 milliwatts per square centimeter [mW/cm2] for 20 seconds) and light-emitting diode (LED) curing light in 3 modes (1000 mW/cm2 for 20 seconds, 1000 mW/cm2 for 10 seconds, and 3200 mW/cm2 for 3 seconds). The curing distance was 5 mm, and temperature changes were recorded with a thermal camera. Microcomputed tomography scanning measured volumetric and linear attachments before and after polymerization. Statistical analyses employed a 1-way analysis of variance with Bonferroni corrected Tukey post-hoc for multiple comparisons and the Kruskal-Wallis test for temperature change. Significant differences (P<0.001) were found in temperature among curing lights. The highest temperature was in the LED unit-extra mode, and the lowest was in the halogen curing unit. The LED unit for 20 seconds caused the highest temperature change. A significant difference (P= 0.048) in occlusal attachment length was found between the LED unit for 20 seconds and the LED unit-extra mode. Polymerization resulted in increased attachment template thickness across all groups, with significant changes noted in the halogen unit, LED unit for 20 seconds, and LED unit-extra mode. Temperature generated during polymerization varied between halogen and LED curing lights. Significant differences were found in attachment length at the occlusal level and template thickness postpolymerization. Preferences in attachment bonding protocols may affect the clinical precision of clear aligner treatments.

Opalescence and Fluorescence of 46 Resin-Based Composites Exposed to Ultraviolet Light

Identifying the boundary between the tooth and the resin-based composite (RBC) is difficult when replacing restorations. Ultraviolet (UV) light has been reported to assist the viewer by causing the RBC to fluoresce. Using a laboratory-grade fiberoptic spectrometer, 46 RBCs were exposed to UV light from the Woodpecker O-Star curing light. The opalescence and fluorescence were measured relative to a human tooth that contained just dentin and a tooth that contained both enamel and dentin. After these quantitative measurements, 10 RBCs with large differences in light emittance were compared qualitatively to assess their brightness when exposed to UV light compared to the dentin specimen and the specimen containing both enamel and dentin. It was found that, when exposed to UV light, some of the RBCs were less bright compared to the two samples of teeth used for comparison, but most were brighter; some were up to six times brighter. The filler appears to affect the opalescence peaks, while the resin appears to affect the fluorescence peaks. It was concluded that because RBCs emit very different levels of opalescence and fluorescence, UV light from the Woodpecker O-Star cannot be relied upon to detect all brands of RBC on the tooth. The opalescence and fluorescence can also be used to detect changes in the formulation of the RBC.

Solid polymer electrolytes with dual salts enhance lithium-metal interfacial stability for long cycle performance of lithium batteries

Solid-state lithium metal batteries (LMBs) are considered to be the ideal energy storage system for achieving higher energy density and high safety. However, poor physical contact at the interface between the solid-state electrolyte and lithium metal, as well as the growth of dendrites make the cycling stability of LMBs challenging. Therefore, we developed a multifunctional ionic liquid-based polymer electrolyte including montmorillonite (MMT) and double salts (NaFSI and LiTFSI). The self-concentration effect of MMT lithium ions, combined with the electrostatic shielding effect of the double salts, resulted in homogeneous ion deposition, reducing dendritic lithium generation and improving lithium battery performance, with lithium batteries achieving a stable cycling rate of 1000 cycles at 1 C. Moreover, Due to the integrated assembly of the battery assembly process using light curing, the physical interface between the positive electrode-electrolyte-negative electrode achieves good contact and wettability. NaFSI achieves the enhancement of solid electrolyte interface (SEI) by introducing NaF/LiF to SEI of lithium metal, and the optimization of ion deposition pattern at the interface can be achieved by electrostatic shielding effect. Ultimately, stable ion transport at the solid-solid interface for lithium metal solid-state batteries can be realized. Notably, the ionic liquid-based polymer electrolyte with high ionic conductivity (1.2 × 10−3 S cm−1) and high oxidative stability (5.2 V vs. Li/Li+) at room temperature. In addition, the good flame retardant properties of the electrolytes indicate that dual-salt polymer electrolytes are an effective strategy for achieving high safety and long cycle stability of LMBs.

The dark art of light curing in dentistry

ObjectiveThis study was designed to show that the commonly reported irradiance values that are quoted in most publications inadequately describe the light output from light curing units (LCUs). MethodsThe total spectral radiant power (mW) output from 12 contemporary LCUs was measured with a fiberoptic spectroradiometer and a calibrated integrating sphere. Five recordings were taken for each LCU and exposure mode. In addition, the irradiances (mW/cm²) delivered at 0-mm, 5-mm and 10-mm distances were recorded through a 6-mm diameter aperture and the radiant exposures (J/cm²) from the LCUs were calculated. Light beam profiles from the LCUs were recorded using a beam profiler, and the images were overlaid on a molar tooth to simulate a clinical setting. Data were analyzed using ANOVA followed by Tukey post-hoc test (α = 0.05). ResultsThe mean power outputs from the LCUs ranged from 380 to 2472 mW (p < 0.0001). The highest irradiance was recorded from the Cicada CV 215-G7 (3091 mW/cm² in its highest mode) and the lowest from the Radii Cal CX (731 mW/cm²). The emission spectra differed, even among the multi-peak and single-peak LCUs. Radiant exposures from the entire light tip ranged from 18.3 J/cm², Radii Cal CX, in its standard 25 s exposure mode to 3.9 J/cm² from the Monet Laser in a 3 s exposure setting. Half (50 %) of the measured irradiance values from the LCUs differed from the manufacturers' value by more than 10 %. There were significant differences in the impact of distance from the tip. The beam profiles visually highlighted the varying effects of distance from the LCU tip among different units. ConclusionThere were significant differences in the emission spectra, power outputs, tip diameters, irradiances, radiant exposures, and the effect distance from the light tips. These differences underline the importance of manufacturers and researchers correctly measuring and reporting the output from the LCU to ensure that research is reproducible and that patients receive acceptable dental restorations. Clinical SignificanceThis article alerts clinicians, researchers and journal editors that providing only the tip irradiance (radiant exitance) value from the LCU is no longer sufficient. Manufacturers and researchers should include information on the spectral radiant power, emission spectrum, tip diameters, and also the effect of distance on the irradiance and radiant exposure, beam profiles and tooth access information when describing an LCU.

Direct Composite Restorations on Permanent Teeth in the Anterior and Posterior Region - An Evidence-Based Clinical Practice Guideline - Part 2: Recommendations for Composite Processing.

Part 2 of this German S3 clinical practice guideline provides recommendations for the process of manufacturing composite restorations. It covers key aspects like caries removal, field isolation, matrix and adhesive techniques, as well as light curing and polishing. The outcomes of interest include survival rates and restoration quality. A systematic literature search was conducted by two methodologists using MEDLINE and the Cochrane Library via the OVID platform, including studies up to December 2021. Additionally, the reference lists of relevant manuscripts were manually reviewed. Six PICO questions were developed to guide the search. Consensus-based recommendations were for- mulated by a panel of dental professionals from 20 national societies and organizations based on the collected evidence and ex- pert opinion. The guideline advocates for one-stage selective caries removal near the pulp and underscores the effectiveness of various isolation techniques, adhesive systems, and the crucial role of light polymerization. The use of anatomically pre- formed sectional matrices and phosphoric acid etching is recommended to enhance restoration quality. Additionally, polish- ing composite restorations is advised to improve surface finish. This guideline provides comprehensive recommendations that inform clinicians on optimizing the composite restor- ation manufacturing processes. The adoption of these best practices can improve the quality and longevity of dental restorations.

Effect of Curing Light with Different Intensities on the Penetration of Silver and Fluoride Ions and Dentin Hardness in Primary Carious Molars Following Silver Diamine Fluoride Application: A Comparative Microscopic Ex Vivo Study.

A paradigm shift from surgical to medical approach for caries management has popularized silver diamine fluoride (SDF) as a preventive and interim caries arrest medicament. Few studies conducted have explored the effect of curing light on SDF's microbial property, its penetration, and effect on dentin. However, there is a research gap regarding the effect of different intensities of curing light on SDF performance. To determine the effect of different curing light intensities on SDF penetration depth and dentin hardness in carious lesions of primary molars. Silver diamine fluoride was applied on 30 extracted carious primary molars. Teeth were randomly allocated into three groups-(1) control group, no light curing after application of SDF; (2) light curing of SDF with low intensity (1000 mW/cm2); and (3) light curing of SDF with high intensity (2500 mW/cm2). A scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis was performed to check ion penetration after 1 week, and a Vickers hardness test was used to assess dentin hardness of both infected and affected dentin layers at 1-week and 1-month intervals. Based on the distribution of data, parametric and nonparametric tests were applied. Statistical Package for the Social Sciences (SPSS) version 26 was used for statistical analysis. The level of significance was set at 5%. Silver diamine fluoride penetrated beyond the carious lesion in all three groups. The mean silver ion precipitation in infected dentin in group III (16.90 ± 0.68) was maximum, whereas it was found to be minimum in group II (7.31 ± 0.63). The mean fluoride ion precipitation in affected dentin in group III (4.06 ± 0.41) was highest and least in group II (3.09 ± 0.58). A considerable increase in mean dentin hardness of infected dentin was observed in all three groups (214.00 ± 89.06, 218.00 ± 75.17, 231.00 ± 98.86, respectively; p < 0.001) after 1 month. Applying SDF to carious lesions using a high-intensity dental curing light induced more silver ion precipitation in infected dentin and increased its hardness. Bhatt R, Patel M, Thakkar A, et al. Effect of Curing Light with Different Intensities on the Penetration of Silver and Fluoride Ions and Dentin Hardness in Primary Carious Molars Following Silver Diamine Fluoride Application: A Comparative Microscopic Ex Vivo Study. Int J Clin Pediatr Dent 2024;17(7):766-772.

Diversity of short-term DC outcomes in bulk-fill RBCs subjected to a 3 s high-irradiance protocol

ObjectivesTo determine the short-term (5 min) initial effects of a high-irradiance light-curing (LC) protocol on light transmission (LT%), radiant exposure (RE) and degree of conversion (DC%) of different bulk-fill resin-based composites (RBCs). Materials and methodsSix bulk-fill composites with different viscosities were investigated: OBF (One Bulk Fill, 3 M), EB (Estelite bulkfill,Tokuyama), PFill, PFlow, ECeram and EFlow (PowerFill, Poweflow, Tetric EvoCeram bulkfill, Tetric Evoflow bulkfill, Ivoclar), subjected to different LC protocols: one ultra-high-intensity (3 W/cm2 −3 s via PowerCure LCU) and two conventional (1.2 W/cm2 −10 s and 20 s via PowerCure and Elipar S10 LCUs). Specimens (n = 5) were polymerized within their molds (ϕ5 mm × 4 mm depth) to determine LT% and RE at 4 mm using a MARC-LC spectrometer. For real-time DC% measurements by FTIR, similar molds were utilized. Data were analyzed by one-way ANOVA and Tukey post-hoc tests at 5 % significance. ResultsRegardless of the applied LC protocols, OBF and low-viscosity RBCs (EB, PFlow and EFlow) had the lowest and highest LT%, RE, DC% and RPmax, respectively. RE results of all RBCs were in the same sequence: Elipar-20 s > PCure-10 s > PCure-3 s. DC% of PFill and PFlow displayed no significant difference between the applied LC protocols (p > 0.05). The polymerization kinetic in all materials was well described by an exponential sum function (r2 varied between 0.85 and 0.98), showing a faster polymerization with the PCure-3 s protocol. SignificanceThe measurement of LT% and DC% at 5 min gave an insight into the developing polymerization process. The initial response of these bulk-fill composite to a high-irradiation protocol varied depending on their composition and viscosity, being faster for low viscosity materials. Nevertheless, even though multiple resin composites are designed to be efficient during photopolymerization, care should be taken when selecting materials/curing protocol.

A comprehensive review on impact of post-harvest management and treatment practices on the quality of garlic (Allium sativum L) during storage

Garlic (Allium sativum L.) plays a crucial role in global agriculture due to its culinary and medicinal uses, but it faces significant post-harvest losses due to moisture, temperature fluctuations, and pest infestations. Proper storage and handling practices can mitigate these losses, yet conventional methods like curing, dehydration, cryopreservation, and vacuum sealing still result in 25–40 % losses during storage. This review investigates the types, factors, and causes of garlic losses, focusing on biological factors such as microbial infections pest infestations, and premature sprouting which cause decay and deformities. Physical factors such as mechanical damage, inadequate curing, temperature fluctuations, humidity, and prolonged light exposure also contribute to deterioration. This review explores practices and treatments to minimize losses, detailing their mechanisms, benefits, and commercial potential. It compares thermal and non-thermal technologies such as irradiation, ozone treatment, nanotechnologies, edible coatings, and films. Irradiation is effective against pathogens but may lead to nutrient loss, ozone treatment provides microbial control with minimal residue. Nanotechnologies, edible coatings, and films help extend shelf life by reducing microbial growth and moisture loss, with considerations for safety and consumer acceptance. The review highlights the need for innovative solutions to reduce losses and preserve the nutritional value and safety, contributing to sustainable garlic production and food security. Additionally, it evaluates the implications of these management practices for sustainability and circular economy. The findings highlight the need for further research to enhance the efficiency, cost-effectiveness, and environmental sustainability of post-harvest technologies to ensure the long-term viability and profitability of garlic production.

Effect of different surface treatments and adhesive cementation on the surface topography and flexural strength of translucent and ultra-translucent monolithic zirconia.

To evaluate the effect of different surface treatments and adhesive cementation on the miniflexural strength (MFS) of monolithic zirconia. Two-hundred and forty (240) sintered bars of translucent zirconia (ZT) and ultra-translucent zirconia (ZUT) were obtained (8 mm ×2 mm ×1mm). The bars were divided into 16 groups (n = 15) according to the factors "Zirconia" (ZT and ZUT), "Cementation" (Cem) and "surface treatment" (Ctrl:Control, Al:Aluminum oxide/Al2O3 50 µm, Si:Silica/SiO2 coated alumina particles oxide 30 µm, Gl:Glazing+hydrofluoric acid). Half of the bars received an adhesive layer application, followed by application of resin cement and light curing. The surface roughness was measured in non-cemented groups. All the bars were subjected to the MFS test (1.0mm/min; 100 kgf). Scanning electron microscopy was used for qualitative analyses. MFS data (MPa) and roughness (µm) were statistically evaluated by three-way and two-way ANOVA respectively and Tukey's test (5%). The surface treatment and the interaction were significant for roughness. Glazing promoted less roughness compared to silicatization. Regarding MFS, only the zirconia and surface treatment factors were significant. For ZT, the sandblasted groups had an increase in MFS and glazing reduced it. There was no difference between the groups without cementation for the ZUT; however, ZUT.Si/Cem, and ZUT.Al/Cem obtained superior MFS among the cemented groups. Sandblasting increases the flexural strength for ZT, while glaze application tends to reduce it. Applying resin cement increases the flexural strength of ZUT when associated with sandblasting. Sandblasting protocols promote greater surface roughness.

Preparation and Performance of Chitosan-gallic acid/Methacrylic Anhydride Composite Antibacterial Hydrogel

Firstly, chitosan-gallic acid derivative (GA-CS) was prepared by reacting chitosan (CS) with gallic acid (GA), which was combined with chitosan (CM) modified by methacrylic anhydride (MA) acylation as an antibacterial modifier, and the composite hydrogel was prepared by light curing. The mechanical properties, swelling rate, surface contact angle, water retention and micromorphology of the hydrogel were tested to explore the effect of GA-CS on the antibacterial effect of the composite hydrogel. The results showed that the compressive strength of the composite hydrogel was 225kPa, and with the addition of the antimicrobial monomer GA-CS, the antibacterial effect and water retention rate of the composite hydrogel increased. However, the surface contact angle with water increased compared with that without GA-CS, and the swelling rate decreased. When the mass ratio of GA-CS to CM was 2:98, the diameter of the inhibition zone increased from 9.85mm to 13.96mm of the pure chitosan sample, the surface contact angle with water was 17.6°, the swelling rate of the sample was 79.32% in 24 hours, and the water content of more than 50% could be maintained for about 7 hours.

Effects of light curing on silver diamine fluoride-treated carious lesions: A systematic review.

This systematic review aims to evaluate the potential benefits and underlying mechanisms of combining SDF with light curing, based on available studies. A systematic search of publications was conducted with the keywords "silver diamine fluoride" or "silver fluoride" and "dental light curing," "LED curing," "dental laser," and "dental polymerization" in 4 databases: PubMed, EBSCO, Scopus, and Google Scholar to identify English-language articles published up to March 2023. Duplicate publications were deleted. Two reviewers screened the titles and abstracts and excluded irrelevant publications. The full text of the remaining publications was retrieved. Studies investigating the effect of light-curing on SDF-treated carious lesions were included. The 175 publications initially found included 5 laboratory studies investigating the effects of light curing on 38% SDF-treated dentine carious lesions, but no clinical study was found. Four of these studies were conducted on extracted primary teeth, and one was on extracted permanent teeth. SDF with light curing increased microhardness (n = 3, p < .05) showed a higher mineral density (n = 1, p < .041) and had more silver ion precipitation in infected dentine (n = 1, p < .016) compared to SDF without light curing. Moreover, no significant differences in the antibacterial activity were observed between SDF with light curing and SDF alone (n = 1, p > .05). Drawing from the limited number of laboratory studies, incorporating light curing subsequent to the SDF application yields potential favorable outcomes that include augmented microhardness, elevated mineral density, and heightened silver ion precipitation within infected dentine. Future clinical research is required to confirm or refute the benefit of light curing on SDF-treated carious lesions.

Scalable production of double-layer superhydrophobic coating with superior adhesion and high corrosion resistance via screen printing and UV curing

This study addresses the challenges of mass production and extensive application of superhydrophobic coatings, focusing on adhesion and durability. We propose an innovative solution utilizing screen printing and UV curing techniques, offering a simple, replicable, and scalable process. Our two-step strategy involves applying a polyurethane diacrylate (PUA-2) adhesion layer to the glass surface through screen printing and UV curing to ensure superior adhesion. Next, a polyurethane hexaacrylate (PUA-6) based formulation is applied over the adhesion layer and subjected to light curing, resulting in excellent hydrophobicity, scratch resistance, and corrosion resistance. This method withstands a pullout force exceeding 5 MPa, achieving a water contact angle of 164.3° and a sliding angle of 1.6°. The coating maintains favorable superhydrophobicity after 80 rounds of sandpaper friction and demonstrates promising corrosion resistance in a 3.5 % NaCl solution. Notably, this approach streamlines large-scale production and delivers exceptional, well-defined performance, providing a promising avenue for widespread and sustainable applications of superhydrophobic coatings.

Effect of shade and thickness on the microhardness of resin-based composite specimens at different points considering curing light beam’s inhomogeneity

BackgroundRecent studies have reported the inhomogeneity in the light emitted by dental light-curing units (LCUs). It is essential to understand how this uneven light distribution affects the physical properties of resin-based composites (RBCs) at various points across their surfaces. This study aimed to evaluate the effect of LCU beam’s inhomogeneity on the microhardness of RBCs with different shades and thicknesses.MethodsFour body (A1B, A2B, A3B, and A4B), one dentin (A3D), and one enamel shade (A3E) of RBC (Filtek Z350 XT) were examined. The specimens were fabricated in four thicknesses (1, 2, 3, and 4 mm) and subjected to a 40-second light-curing. Vickers microhardness testing was performed at the center point, and 3 mm left and right from the center at the bottom surface of each sample. The LCU beam profile was characterized using a beam profiler, while irradiance after specimen passage was measured using a spectrometer. One-way analysis of variance (ANOVA) and Tukey’s post-hoc tests were used to analyze the effects of shades and thicknesses on irradiance and microhardness, respectively. One-way repeated-measures ANOVA was used to compare the microhardness across different points. Pearson’s correlation analysis examined the relationship between irradiance and microhardness.ResultsThe beam profile of LCU revealed inhomogeneous light distribution. Light irradiance was decreased with both the increase in thickness and darker shade of the specimens (p < 0.05). Microhardness was found to decline with an increase in sample thickness (p < 0.05), and was consistently higher at the center point compared to the periphery, particularly in thicker (3 and 4 mm) and darker shades (A3B, A4B, and A3D). A positive correlation was found between the irradiance and microhardness across all evaluated points (p < 0.05).ConclusionsInhomogeneous light emission from LCU significantly influences the microhardness of RBC samples, depending on the thicknesses and shades. The findings underline the importance of considering LCU beam inhomogeneity in clinical settings to ensure optimal polymerization of RBC.

The Effect of the Initiator/Activator/Accelerator Ratio on the Degree of Conversion, Film Thickness, Flow, and Cytotoxicity of Dual-Cured Self-Adhesive Resin Cements.

Although self-adhesive resin cements are convenient and less technique-sensitive materials for dental clinicians, they exhibit a lower degree of conversion due to acidic components in their composition. Supplementation of the initiator, accelerator, and activator in self-adhesive resin cements has been suggested to compensate for the lower degree of conversion. This study aimed to evaluate the effects of different combinations of self-curing initiators, self-curing activators, and accelerators on the degree of conversion (DC) of self-adhesive resin cements. A dual-cured self-adhesive resin was prepared using six combinations of initiators, activators, and accelerators. The change in the DC over time was evaluated with and without light curing. The film thickness, flow properties, and cytotoxicity of each formulation were assessed. The results showed that all supplemental components had an effect on increasing the DC, but a greater increase in the DC was observed in the following order: activator, accelerator, and initiator. The cytotoxicity of the resin cements was related to the DC values, as resin cements with lower DC values exhibited higher cytotoxicity. The film thickness met the ISO standards for all groups. The results suggest that utilizing an activator is the most effective approach to enhance the DC in self-adhesive resin cement and that cytotoxicity tended to increase with lower DC values, whereas film thickness and flow properties demonstrated no correlation with DC values.