Surface Sealant Research Articles

The effect of surface sealants with different filler content on microleakage of Class V resin composite restorations.

Objective:Microleakage is still one of the most cited reasons for failure of resin composite restorations. Alternative methods to prevent microleakage have been investigated increasingly. The aim of this study is to evaluate the microleakage in Class V resin composite restorations with or without application of surface sealants with different filler content.Materials and Methods:Ninety-six cavities were prepared on the buccal and lingual surfaces with the coronal margins located in enamel and the cervical margins located in dentin. The cavities restored with an adhesive system (Clearfil SE Bond, Kuraray, Tokyo, Japan) and resin composite (Clearfil Majesty ES-2, Kuraray, Tokyo, Japan). Teeth were stored in distilled water for 24 h and separated into four groups according to the surface sealants (Control, Fortify, Fortify Plus, and G-Coat Plus). The teeth were thermocycled (500 cycles, 5–55° C), immersed in basic fuchsine, sectioned, and analyzed for dye penetration using stereomicroscope. The data were submitted to statistical analysis by Kruskal–Wallis and Bonferroni–Dunn test.Results:The results of the study indicated that there was minimum leakage at the enamel margins of all groups. Bonferroni–Dunn tests revealed that Fortify and GC-Coat groups showed significantly less leakage than the Control group and the Fortify Plus group at dentin margins in lingual surfaces (P < 0.05).Conclusion:The all surface sealants used in this study eliminated microleakage at enamel margins. Moreover, unfilled or nanofilled surface sealants were the most effective in decreasing the degree of marginal microleakage at dentin margins. However, viscosity and penetrability of the sealants could be considered for sealing ability besides composition.

Effect of denture-coating composite on Candida albicans biofilm and surface degradation after disinfection protocol

Denture stomatitis is the most common pathology affecting denture wearers and its main cause is colonisation of dentures with Candida albicans. This study investigated the effectiveness of two commercial composite surface sealants (Biscover(®) LV and Surface Coat(®)) to reduce C. albicans biofilm colonisation on denture resin, as well as their surface integrity after disinfection cycles with 1% sodium hypochlorite solution. Heat-cured acrylic resin specimens were manufactured (10 mm × 10 mm × 1 mm). The specimen surfaces were mechanically polished to simulate rough or smooth denture surfaces. Four surface-treatment groups were tested: smooth surfaces [0.3 μm of mean roughness (Ra)]; rough surfaces (3 μm of Ra); rough surfaces treated with Biscover(®) LV; and rough surfaces treated with Surface Coat(®). Specimens of each group were randomly divided to undergo immersion in distilled water or 1% sodium hypochlorite for 30 or 90 cycles each. Specimens of all groups in each immersion solution were tested using a crystal violet (CV) staining assay for biofilm quantification and by scanning electron microscopy for visual analyses of surface integrity and biofilm structure. CV assay data were analysed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison test (P < 0.05). The effectiveness and surface integrity of Biscover(®) LV-treated surfaces were similar to those of smooth surfaces, whereas Surface Coat(®) -treated surfaces presented a similar performance to rough surfaces in all solutions and cycles. These results suggest the possibility of clinical use of Biscover(®) LV for denture coating on surfaces in which mechanical polish is not indicated, such as the fitting surface.

Effect of sealant agents on the color stability and surface roughness of nanohybrid composite resins

Statement of problemThe effect of sealant agents on the surface roughness and color stability of nanohybrid composite resins is unknown. PurposeThe purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of 4 nanohybrid composite resin materials. Material and methodsForty disks (10×2 mm) were fabricated for each nanohybrid composite resin material (Z-550, Tetric EvoCeram, Clearfill Majesty, Ice) (N=160) and divided into 4 surface treatment groups: 1 conventional polishing (control) and 3 different sealant agent (Palaseal, Optiglaze, BisCover) coupling groups (n=10). The specimens were thermocycled, and surface roughness (Ra) values were obtained with a profilometer. Scanning electron microscope images were also recorded. CIELab color parameters of each specimen were measured with a spectrophotometer before and after 7 days of storage in a coffee solution. Color differences were calculated by the CIEDE 2000 (ΔE00) formula. The data were statistically analyzed by 2-way ANOVA and by the Tukey HSD test (α=.05). ResultsThe surface treatment technique significantly affected the Ra values of the composite resins tested (P<.001). The interaction between the surface treatment technique and composite resin material was also significant for ΔE00 values (P<.05). Within the composite resin groups, significant decreases in Ra were observed only for the Palaseal agent coupled composite resin groups (except Ice) compared with the control groups (P<.05). Scanning electron microscope images revealed rougher surfaces with conventionally polished groups compared with test groups. Conventionally polished groups had the highest ΔE00 (3.09 to 3.49) values for each composite resin group, except for BisCover applied Clearfill Majesty (P<.05). Within the composite resin groups, significant differences were observed between the color change seen with BisCover and other sealants for Clearfill Majesty composite resin (P<.05). ConclusionsUsing Palaseal agent on all tested composite resins except for Ice produced smoother surfaces. All surface sealant agents provided less discoloration of nanohybrid composite resins after coffee staining compared with conventional polishing except for BisCover applied Clearfill Majesty composite resin.

Color stability of a resin composite: Effect of the immersion method and surface treatments.

In vitro staining methods expose the entire specimen to staining solutions. In a real clinical situation, this is not observed, since one should consider that the bonded surface is not exposed to the oral environment. Theoretically, the clinical condition would be the best simulated if the specimens were exposed to staining solutions by partial immersion. To evaluate if different immersion methods and surface treatments influence the color stability of resin-based specimens. A stainless steel matrix was used to prepare 30 disc-shaped specimens that were randomly allocated in three groups: Without polishing, polishing with abrasive discs, and surface sealant. Half of the specimens were isolated to maintain only the upper surface exposed to staining (partial immersion) and the other half was totally immersed in coffee solution for 48 h (total immersion). The coordinates ΔE*, ΔL*, Δa*, Δb* were assessed by spectrophotometer. Two-way ANOVA and Tukey's post hoc tests (α =0.05). Specimens submitted to partial immersion showed lower values of ΔE*, ΔL*, Δa*, Δb*, in comparison to total immersion (P = 0.000). Specimens covered by a surface sealant presented lower ΔE* values regardless of the immersion method. Specimens totally immersed in staining solutions could in somehow overestimate the color change, once that in most clinical conditions not all of the restoration surfaces are exposed to the oral environment. Moreover, as the surface sealant application produces color change values that are clinically acceptable, it might be used in esthetic restorations as an adjunct treatment.

Investigating Effects of Water Conditioning on the Adhesion Properties of Crack Sealant

This paper investigates the effect of water exposure on three different crack sealants commonly used in cold, moderate and hot climates. It is hypothesized that water penetrates into the interface between crack sealant and substrates causing progressive adhesion failure and that the rate of failure varies depending on the sealant’s surface chemistry as relates to its interaction with water molecules in different environmental conditions. Accordingly, this paper measures the change in sealant’s adhesion strength and surface energy before and after water conditioning. To study adhesion strength and its change due to water conditioning, three different types of sealant were tested using Direct Adhesion Tester (DAT). It was found that the adhesion strength of all three crack sealants reduces due to water exposure. In addition, to evaluate the surface properties and water phobicity of each sealant, the contact angle between a droplet of water and sealant surface was measured before and after conditioning at different temperature. The objective of the latter experiment was to determine whether sealants susceptibility to water would vary with pavement surface temperature. To do so, a sessile drop method utilizing FTA-1000 was used to determine the contact angle for each of the aforementioned water-sealant pairs at different temperatures. The results obtained were further used to calculate the work of adhesion at each scenario to be correlated to mechanical adhesion strength measured with DAT.

Efficacy of denture cleaners on the surface roughness and Candida albicans adherence of sealant agent coupled denture base materials.

This study investigated the effect of denture cleansers on the surface roughness and Candida albicans adherence of surface sealant agent coupled denture base resins. One hundred and twenty specimens were fabricated from 2 polymethyl methacrylate (PMMA) (Meliodent; Acron MC) and 1 polyamide (Deflex) denture base materials, coated with a sealant agent (Palaseal) and divided into 4 groups (n=10) according to overnight cleaning procedures: distilled water (control), 5% sodium hypochlorite (NaOCl) and two different sodium perborate (Corega; Rapident). The surface roughness values were measured with a profilometer before (Ra0) and after 90 days immersion in denture cleaners (Ra1). Specimens were incubated with Candida albicans suspension and Candida colony- forming units (CFU) (Cfu/mm) were counted. Significant differences were found, between the Ra0 and Ra1 values of 5% NaOCl applied Acron MC, Deflex and also Rapident applied Deflex groups (p<0.05). Denture cleaning procedures had no significant effects on the quantitiy of Candida albicans.

Effect of different surface treatment methods on the surface roughness and color stability of interim prosthodontic materials

Statement of problemThe effects of surface sealant agents on the surface roughness and color stability of interim crown materials are unknown. PurposeThe purpose of this in vitro study was to evaluate the effects of different polishing methods on the surface roughness and color stability of 4 interim crown materials. Material and methodsA total of 160 specimens were fabricated from 2 poly(methyl methacrylate) (PMMA; Tab 2000, Dentalon Plus) and 2 bis-acryl (Tempofit, Protemp 4) interim crown materials and divided into 4 groups (n=10) according to applied surface treatment procedures: conventional polishing (control) and 3 surface sealant (Palaseal, Optiglaze, Biscover) coupling methods. Surface roughness (Ra) values were measured with a profilometer. Color parameters were measured with a spectrophotometer before and after staining in coffee. Color differences (CIEDE 2000 [ΔE00]) were calculated. Data were statistically analyzed with 2-way ANOVA and the Tukey honest significant differences test (α=.05). ResultsThe Ra values of Tempofit with Biscover were significantly lower than their control group, Tab 2000 and Dentalon Plus control groups (P<.05). The highest ΔE00 was calculated for Tempofit control (P<.05). The Dentalon Plus control group had significantly higher ΔE00 values than the other groups, except for the Tempofit and Tab 2000 control groups.The Tab 2000 control ΔE00 was significantly higher than the other groups, except for Dentalon Plus with Palaseal and Dentalon Plus with Optiglaze. ConclusionsAll specimens had a surface roughness higher than the plaque accumulation threshold (0.20 μm). Smoother surfaces were observed for Tempofit with Biscover when compared with theTempofit control. The color change observed with the Dentalon Plus, Tab 2000, and Tempofit control groups was clinically unacceptable. Nonperceivable color changes were seen with Protemp 4 with Optiglaze, Tempofit with Optiglaze, and Tempofit with Biscover. Perceivable but clinically acceptable color changes were observed when sealants were used for all other test groups and Protemp 4 control.

Chemical, mechanical and biological properties of contemporary composite surface sealers

ObjectivesTo evaluate the chemical, mechanical, and biological properties of modern composite surface sealers (CSS) having different compositions. MethodsThe CSS products tested were Biscover LV (BC), Durafinish (DF), G-Coat Plus (GC), and Permaseal (PS). The tests performed were: (A): degree of conversion (DC%) by ATR-FTIR spectroscopy; (B): thickness of O2-inhibition layer by transmission optical microscopy; (C): surface hardness, 10min after irradiation and following 1 week water storage, employing a Vickers indenter (VHN); (D): color (ΔE*) and gloss changes (ΔGU) after toothbrush abrasion, using L*a*b* colorimetry and glossimetry; (E): accelerated wear (GC,PS only) by an OHSU wear simulator plus 3D profilometric analysis, and (F): cytotoxicity testing of aqueous CSS eluents on human gingival fibroblast cultures employing the methyl-3H thymidine DNA labeling method. Statistical analyses included 1-way (A, B, ΔE*, ΔGU) and 2-way (C, F) ANOVAs, plus Tukey post hoc tests. Student's t-test was used to evaluate the results of the accelerated wear test (α=0.05 for all). ResultsThe rankings of the statistical significant differences were: (A) PS (64.9)>DF,BC,GC (56.1–53.9) DC%; (B) DF,PS (12.3,9.8)>GC,BC (5.2,4.8) μm; (C): GC (37.6)>BC,DF (32.6,31.1)>PS (26.6) VHN (10min/dry) and BC,DF (29.3,28.7)>GC(26.5)>PS(21.6) VHN (1w/water), with no significant material/storage condition interaction; (D): no differences were found among GC,DF,BC,PS (0.67–1.11) ΔE*, with all values within the visually acceptable range and PS,BC (32.8,29.4)>GC,DF (19.4,12.9) ΔGU; (E): no differences were found between GC and PS in volume loss (0.10,0.11mm3), maximum (113.9,130.5μm) and mean wear depths (30.3,27.5μm); (F): at 1% v/v concentration, DF showed toxicity (23% vital cells vs 95–102% for others). However, at 5% v/v concentration DF (0%) and BC (9%) were the most toxic, whereas GC (58%) and PS (56%) showed moderate toxicity. SignificanceImportant chemical, mechanical, and biological properties exist among the CSS tested, which may affect their clinical performance.

The effect of bonding and surface sealant application on postoperative sensitivity from posterior composites.

The purpose of the study was to evaluate the postoperative sensitivity of posterior Class I composite restoration at short-term, restorated with two different all-in-one self-etch adhesives with or without surface sealant application. 44 restorations were inserted in 11 patients who required Class I restorations in their molars. Each patient received 4 restorations, thus four groups were formed; (1) G-Aenial Bond (GC, Japan); (2) Clearfil S3 Bond (Kuraray, Japan); (3) G-Aenial Bond+Fortify Plus (Bisco, USA), (4) Clearfil S3 Bond+Fortify Plus. Sensitivity was evaluated at 24h, 7, 15, and 30 days using cold air, ice, and pressure stimuli using a visual analog scale. Comparisons of continuous variables between the sensitivity evaluations were performed using the Friedman's One-Way Analysis of Variance with repeated measures test (p<0.05). The type of adhesive used and the application of a surface sealant had no significant effects in postoperative sensitivity (p>0.05). The use of Clearfil S3 Bond resulted in almost the same level of postoperative sensitivity as did the use of G-Aenial Bond. The highest sensitivity scores were observed for the surface sealant applied teeth without any statistical significance (p>0.05). Self etch adhesives displayed postoperative sensitivity. The sensitivity scores slightly decreased at the end of 30 days (p>0.05). Surface sealant application did not result in a decrease in sensitivity scores for either dentin adhesives.

Novel storage technologies for raw and clarified syrup biomass feedstocks from sweet sorghum (Sorghum bicolor L. Moench)

Attention is currently focused on developing sustainable supply chains of sugar biomass feedstocks for new, flexible biorefineries. Fundamental processing needs identified by industry for the large-scale manufacture of biofuels and bioproducts from sweet sorghum (Sorghum bicolor L. Moench) include stabilization and concentration of juice into syrup for long-term storage, year-round supply, efficient transport, and acceptable end-product yields. Pilot plant studies were conducted to evaluate the storage (up to 160 days at ∼25 °C) of raw and clarified syrups from sweet sorghum hybrid and commercial cultivars. Clarified syrups were manufactured after clarification of juice (80 °C; 5 ppm polyanionic flocculant) at various target limed pHs (6.1–6.8) followed by vacuum evaporation. All 70 Brix raw syrups were susceptible to microbial deterioration on the surface during storage, and raw syrups were more susceptible than clarified syrups. Surface deterioration was mainly fungal since bacterial growth was inhibited by low water activity. Juice clarification reduced the loss of fermentable sugars during the evaporation stage and, generally, allowed for better storage of syrup up to 80 days. Target clarification pH had a dramatic effect on the storage of clarified 70 Brix syrups with more acidic pHs reducing fungal deterioration. Further studies are now warranted on the post-evaporation pH adjustment of raw and clarified syrups to <6.1 for long-term storage. Inexpensive soy bean oil and candellila wax showed promise as surface sealants to preserve syrups for at least 80 days of storage at ∼25 °C, also warranting further investigation.

Alkali–Silica Reaction Identification and Remediation at Northwest Arkansas Regional Airport

AbstractNorthwest Arkansas Regional Airport (International Air Transport Association Code, XNA) opened in 1998. XNA is a regional airport serving the northwest Arkansas area. Alkali silica reaction (ASR) was detected at XNA’s runway 16/34 in 2002, and in 2012 the runway was closed for replacement. The airport includes a single runway; therefore, runway replacement required the construction of a temporary alternate landing surface (ALS). Consequently, costs related to the premature runway replacement were substantial. XNA is experiencing significant pavement distress caused by ASR. Therefore, in addition to the runway, taxiways and apron areas will require replacement. The article reviews ASR, causes of ASR at XNA, and a preliminary investigation to develop a remediation approach to ASR at XNA. For ASR remediation, the authors are investigating various surface sealants for their effectiveness to retard ASR, to provide XNA operators additional time before future pavement replacement is warranted.

EFFECT OF SURFACE SEALING ON STAIN RESISTANCE OF A NANO-HYBRID RESIN COMPOSITE

This study investigated the influence of sealant application on stain resistance of a nanohybrid resin composite compared to the efficacy of a bonding agent used as a surface sealant on prolonging color stability of the resin composite. 28 disc-shaped materials were prepared from a nano-hybrid resin composite Filtek Z550 and assigned to four groups: G1K: nonsealed; G2:Adper Single Bond; G3: Fortify ; G4: Biscover LV. After 24 h storage in distilled water at 37˚C, all specimens were subjected to thermocycling and immersed into coffee solution. Color measurements were performed using spectrophotometer (VITA Easyshade; Vident) according to CIEL*a*b* system. Color change values were significantly different among the groups in each evaluation period except for after thermocycling (p<0.05). For 7 days evaluation period, the difference between G3 and G4 group was statistically significant while G4 exhibited statistically significant differences (p<0.05 and p<0.0001 respectively) compared to control (G1) in 14 day whereas no significant difference was found between GI and GII in 28-day evaluation period. However, ΔE values of sealed specimens (GIII, GIV) differed significantly from non-sealed (GI) specimens after 28 days of immersion in coffee solution (p<0.05 and p<0.0001 respectively). It may be concluded that using a bonding agent as a surface sealant does not increase stain resistance of resin composites of the sealants evaluated. Biscover LV showed the highest efficacy to prolong color stability of the resin composite.

Influence of surface sealant agents on the surface roughness and color stability of artificial teeth

Statement of problemAlthough various surface sealant agents are available and recommended for chairside polishing procedures, their effect on the surface roughness and color stability of denture teeth is not clear. PurposeThe purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of various denture tooth materials. Material and methodsEighty disk-shaped specimens were prepared for each type of denture tooth material (SR Vivodent, PMMA; Vitapan, reinforced-PMMA; SR Phonares II, composite resin). The specimens were assigned to 4 groups according to the surface treatment used (n=20): surface sealant agents (Palaseal; Heraeus Kulzer GmbH, Optiglaze; GC Corp Biscover; Bisco Inc) and a conventional laboratory polishing technique (control group). A thermal cycling procedure was applied for half of the specimens (n=10). The surface roughness (Ra) values of thermocycled and nonthermocycled specimens were measured with a profilometer. The CIELab color parameters of both thermocycled and nonthermocycled specimens were measured with a spectrophotometer at baseline and after 7-day storage in a coffee solution. The color differences were calculated from the CIEDE2000 (ΔE00) formula. Data were statistically analyzed with 3-way ANOVA and the Tukey HSD test (α=.05). ResultsThe type of tooth material, surface treatment technique, and their interactions were significant for Ra values, and each variable and their interactions were also significant for ΔE00 values (P<.05). Thermal cycling had a significant effect only on ΔE00 values (P<.05). ConclusionsPalaseal and Optiglaze sealant agents provided smoother and more color-stable denture tooth surfaces than the conventional polishing technique. The use of the Biscover agent with SR Vivodent and Phonares II teeth increased the Ra values. The color of conventionally polished SR Vivodent and Phonares II teeth changed more with thermal cycling.

Influence of Surface Sealers on the Properties of Internally Cured Cement Mortars Containing Saturated Fine Lightweight Aggregate

AbstractTo date, internal curing (IC) has been widely accepted as a promising way to mitigate the autogenous shrinkage of high-performance concretes (HPCs). While extensive studies have confirmed the benefits of internal curing to HPCs cured under sufficient moisture, the durability implications of early-age drying remain unclear for internally cured cement-based materials. As such, this work investigates the influence of early-age drying on the properties of internally cured cement mortars containing saturated fine lightweight aggregate (LWA). The tests conducted on cement mortars with or without internal curing include: drying shrinkage, moisture loss, compressive strength, splitting tensile strength, water absorption, and gas permeability. Additionally, two surface sealers were individually applied to mortars and evaluated for their effectiveness in reducing the risk of early-age drying. The results reveal that early-age drying significantly offsets the advantages of internal curing of LWA with respect...

Water sorption, solubility and surface roughness of resin surface sealants

Surface sealants have been suggested as final glaze of the surface of composite restorations. However, little is known about bulk and surface properties of these materials aiming the long-term preservation of the surface integrity of these restorations. AIM: To evaluate the water sorption, solubility and surface roughness of commercial surface sealants for restorations. METHODS: Five disc-shaped specimens 15 mm diameter X 1 mm high were made from the surface sealants Natural Glaze DFL and Permaseal Ultradent and were light cured according to the manufacturer's instructions. The specimens were finished with 1500-grit SiC paper. Water sorption WS and solubility SL were assessed as recommended by the ISO 4049/2000 and were expressed in µg/mm3. Surface roughness was evaluated before and after WS and SL, and was expressed in µm as R1 before WS and SL and R2 after WS and SL. It was obtained from three parallel measurements along a 4mm length. Data were analyzed using t-test and paired t-test α=0.05. RESULTS: Water sorption and solubility of Natural Glaze were significantly lower than that of Permaseal p 0.05. CONCLUSIONS: Surface sealants used in composite restorations undergo hydrolytic degradation; however, this degradation seems not to interfere on surface roughness of these materials.

Fluorescence intensity of composite layering combined with surface sealant submitted to staining solutions.

The aim of this study was to evaluate the fluorescence intensity of a composite in different layering techniques combined to a surface sealant submitted to staining solutions. One surface sealant and one composite resin (shades A2-0, A2, and YE) were tested. Specimens were carried out using layering with different shades of composite, and dental blocks (dentin/enamel) were obtained of human molars. Fluorescence intensity measurement performed using a spectrofluorophotometer, before and after storage in cola, orange juice, red wine, and distilled water. Data were subjected to analysis of variance and Fisher's test (α = 0.05). Initially, only A2-O + A2 layering showed fluorescence intensity statistically similar to the natural tooth. Overall, groups sealed showed the highest fluorescence intensity compared with unsealed groups. The aging decreased the fluorescence intensity compared with initial values. Red wine showed the highest decrease on the fluorescence intensity. The fluorescence of composite restorations is dependent of the layering technique and is affected by the diet. The staining solutions decreased the fluorescence intensity, even when the composite resins were sealed. Different shades of the same composite showed distinct fluorescence values, so there should be greater standardization of this property for tooth reconstruction success by the layering technique with large tissue loss.

Water sorption, solubility and surface roughness of resin surface sealants

Water sorption, solubility and surface roughness of resin surface sealants

Friction stir lap joining of 2198 aluminum–lithium alloy with weaving and pulsing variants

Lap joints of 2198-T8 Al–Li alloy in 0.063in. sheet thickness were friction stir welded to investigate the combination of this material and assembly method for the manufacturing of aerospace structures. Along with conventional friction stir welding (FSW), weaved FSW and pulsed FSW (PFSW) were evaluated to determine the potential impact of these variant technologies on weld strength. Additionally, a more traditional flat shoulder tool geometry operated with a tilt angle was compared to a tapered shoulder tool geometry operated at a 0° tilt angle, which offers the possibility of simplifying robotic welding operations. Faying surface sealant, the use of which is critical in aerospace applications, was investigated as well, to determine its impact on weld strength and to characterize its interactions with welding parameters and process variants.

Depth of cure of sealants polymerized with high-power light emitting diode curing lights

To determine whether recommended short curing times of three high-power light emitting diode (LED) curing lights are sufficient to polymerize sealant materials. Opaque-unfilled sealant (Delton LC Opaque), opaque-filled sealant (UltraSeal XT plus), and clear-filled sealant (FluroShield) were light cured in a covered slot-mold using the manufacturers' shortest recommended curing times with three high-power LED lights (3-s VALO, 5-s Fusion, 10-s Smartlite). A 40-s cure with a quartz-tungsten halogen (QTH) light was used as control. Vickers hardness was measured 24 h after curing at the sealant surface and through the depth (0.5 mm increments) (N = 10). Results were analyzed with two-way anova (pair-wise multiple comparisons, significance level 0.05). The high-power LEDs did not cure the sealants as deep as the QTH. Delton LC Opaque showed the least depth of cure as hardness values beyond a depth of 0.5 mm were not measurable regardless of the curing light. Even for UltraSeal XT plus, when surface hardness was about the same with all lights, hardness decreased more rapidly with depth for the LEDs. FluroShield showed the slowest decline in hardness through the depth for all lights. Manufacturers' recommendations for shortest possible curing time with high-power LEDs were not sufficient for adequate polymerization of the tested sealants.

Evaluation of a novel approach in the prevention of white spot lesions around orthodontic brackets

The purpose of this study was to evaluate and compare the relative efficacy of a resin fissure sealant, nano-filled self-adhesive protective coating, resin infiltrant, glass ionomer cement (GIC), and GIC containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in preventing the formation of subsurface lesions of enamel (SLE) adjacent to orthodontic brackets by acting as an enamel surface sealant (ESS). Eighty-five enamel specimens with molar tubes bonded at their centre were randomly divided into five groups, each treated with a different material at the bracket's periphery. Specimens were stored in an acetate demineralization solution at pH 4.5 for 7days at 37 °C then imaged using quantitative light-induced fluorescence (QLF) to determine the difference in fluorescence (∆F) between sound- and acid-exposed enamel. Lesion cross-sections were then examined using backscattered scanning electron microscopy (SEM) to measure lesion depth. The use of GIC alone or incorporating CPP-ACP significantly reduced ∆F compared with other materials. Backscattered SEM images showed no measurable demineralization for enamel treated with either GIC material in contrast with other groups, which showed statistically significant demineralization levels. The fluoride-releasing effects and CPP-ACP benefits of the GIC materials show promise as an effective ESS in inhibiting enamel demineralization adjacent to orthodontic brackets.