UV-curable hyperbranched polyester sealant with tunable mechanical properties.

Different types of wounds have different requirements of a wound sealant. One of the requirements of concern is the adaptability of the mechanical properties of biomaterials to native tissues. However, the mechanical properties of current sealant are untunable or adjustable in a small range normally. Therefore, the scope of application of these sealant is limited. In this study, we developed hyperbranched polyester (HBP)-based UV-curable sealant with tunable mechanical properties. This sealant was cured under UV-light for 2 minutes and exhibited strong adhesion with tissues. The shear adhesive strength of it to the porcine skin ranged between 20-30 kPa, which was higher than the fibrin glue (∼10 kPa). Moreover, the elastic modulus of the sealant in a tensile test ranged between 27-54 MPa, depending on the degree of acrylation of the HBPs. Additionally, we assessed the biocompatibility of the sealant by co-culturing it with mouse mesenchymal stem cells (mMSCs) for 7 days and discovered that the cell viability was unaffected. This sealant with a tunable elastic modulus might be a promising candidate for treating wounds with different elastic moduli.

Ion release and recharge from a fissure sealant containing amorphous calcium phosphate.

To assess- the release of calcium and phosphate ions from a fissure sealant containing amorphous calcium phosphate (ACP), and to determine the re-release capacity of these ions when charged with a solution containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). Nine blocks of ACP resin-based sealant were prepared and immersed in three solutions at different pH (4.0, 5.5, 7.0), and calcium and phosphate ion release was measured with ion chromatography at 1, 3, 5, 7, 14, 21 and 28 days after immersion. Sixty days after immersion, each block was charged with CPP-ACP solution in three 7-day cycles to investigate the re-release of these ions, which was measured on days 1, 3, and 7. No difference was observed in initial calcium ion release at pH 4.0 and pH 5.5. At both values, ion release was significantly higher than at pH 7.0 (p<0.001). Initial phosphate release was significantly different among the three pH values (p<0.001). After re-charging the specimens, calcium ion re-release was greater than phosphate ion release. Initial ion release from ACP resin-based sealant was greatest at the lowest pH. Ion release decreased with time. As the number of recharge cycles increased, ion re-release also improved. Phosphate ion re-release required more recharge cycles than calcium ion re-release.

Anti-biofilm activity of a novel pit and fissure self-adhesive sealant modified with metallic monomers.

Dental plaque is a biofilm composed of a complex oral microbial community. The accumulation of plaque in the pit and fissures of dental elements often leads to the development of tooth decay (dental caries). Here, potent anti-biofilm materials were developed by incorporating zinc methacrylates or di-n-butyl-dimethacrylate-tin into the light-curable sealant and their physical, mechanical, and biological properties were evaluated. The data revealed that 5% di-n-butyl-dimethacrylate-tin (SnM 5%) incorporated sealant showed strong anti-biofilm efficacy against various single-species (Streptococcus mutans or Streptococcus oralis or Candida albicans) and S. mutans-C. albicans cross-kingdom dual-species biofilms without either impairing the mechanical properties of the sealant or causing cytotoxicities against mouse fibroblasts. The findings indicate that the incorporation of SnM 5% in the experimental pit and fissure self-adhesive sealant may have the potential to be part of current chemotherapeutic strategies to prevent the formation of cariogenic oral biofilms that cause dental caries.

Sealing Carious Fissures with Resin Infiltrant in Association with a Flowable Composite Reduces Immediate Microleakage?

Abstract Objective: To compare the immediate microleakage of carious fissures sealed with a caries infiltrant covered by a flowable composite or solely with a flowable composite. Material and Methods: Extracted carious molars (n=20) were selected and paired among the experimental groups according to caries progression scores. Experimental groups (n=10) were divided according to the following sealing techniques: 1) caries infiltrant (Icon) + flowable composite (Z350 flow); 2) flowable composite (Z350 flow). Specimens were immersed in 3% methylene blue and evaluated in a stereomicroscope. Microleakage scores were attributed independently by two calibrated evaluators and the mode value was considered as the mean for the specimen. Binomial tests were used to test differences between two independent sample proportions at 5% significance level. Results: In the flowable composite group, a higher prevalence of dye penetration along the full depth of the fissure was observed, compared with caries infiltrant + flowable composite (p<0.05). For specimens showing dye penetration up to half of the fissure, in caries infiltrant + flowable composite group, all specimens showed dye penetration into the sealant, but not over the infiltrant. Conclusion: Using caries infiltrant as sealing material under a flowable composite cover is effective to improve the immediate sealing ability in carious fissures compared to sealing with flowable composite.

Mineral deposition promoted by resin-based sealants with different calcium phosphate additions.

The aim of this study was to evaluate the influence of different calcium phosphates (CaPs) on the physical, biological, and remineralizing properties of experimental resin-based sealants (RBSs). Triethylene-glycol dimethacrylate (90wt%) and bisphenol A-glycidyl methacrylate (10wt%) were used to produce resin-based sealants. Hydroxyapatite (SHAp), α-tricalcium phosphate (Sα-TCP) and octacalcium phosphate (SOCP) were added to the sealants in a 10wt% concentration. One group without CaPs was used as the control group (SCG). The degree of conversion (DC) was assessed with Fourier-transformed infrared spectroscopy, whereas cytotoxicity was tested with the HaCaT keratinocyte cell line. The ultimate tensile strength (UTS) was used to assess the mechanical strength of the experimental RBSs. Sealed enamel was used for colorimetric assay. Mineral deposition was assessed with Raman spectroscopy after 7, 14, and 28 days of sample immersion in artificial saliva. Scanning electron microscopy was used to analyze the surface morphology after 28 days of immersion. The addition of 10wt% of fillers significantly reduced the DC of sealants. SOCP groups showed reduced cell viability. Higher UTS was found for Sα-TCP and SHAp. The color analysis showed that SGC and demineralized teeth presented higher mismatches with the sound tissue. Mineral deposition was observed for SHAp and Sα-TCP after 7 days, with increased phosphate content and mineral deposits for SHAp after 28 days. RBS with the addition of 10% HAp promoted increased mineralization in vitro after 28 days, and did not affect cell viability, DC, mechanical properties, or RBS color in the enamel.

Microcavitated (ICDAS 3) carious lesion arrest with resin or glass ionomer sealants in first permanent molars: A randomized controlled trial.

OBJECTIVES: Although there is some consensus that carious lesions in early stages (non-cavitated) could be treated using sealants, neither the type of materials nor their use in lesions with localized enamel breakdown (microcavitated) has been reported To compare the efficacy of resin or glass ionomer (GI) sealants in arresting microcavitated carious lesions (ICDAS 3) in first permanent molars. MATERIALS AND METHODS: A double-blinded randomized controlled clinical trial was conducted in 41 healthy 6 to 11-year-old children. At the baseline examination, each subject had at least one carious lesion classified as ICDAS 3 on the first permanent molar. One hundred fifty-one lesions were randomized into: Group 1: resin sealants (76 lesions) and Group 2: GI sealant (75 lesions). Carious lesion progression was assessed clinically and radiographically. Progression and retention failure were the outcomes used for group comparisons at p-value<0.05. RESULTS: After a two-year follow-up, only one lesion progressed to ICDAS 5, without statistically significant differences between the groups (χ2(1) = 0.90, p = 0.53). Radiographically, 100 lesions (98%) were arrested and 2 (2%) showed radiographic progression, without differences between groups (χ2(1) = 0.93, p = 0.93). At 2 years, complete retention was observed in 77% of the resin-based and in 83% of the GI sealants, without statistical differences between type of sealant (χ2(1) = 0.71, p = 0.48). The multilevel mixed model demonstrated that location and type of sealant did not affect retention rates (χ2(1) = 24,98, p < 0.001). CONCLUSION: Sealing ICDAS 3 carious lesions in permanent molars appears to be effective in arresting lesions after a two-year follow-up. Clinicaltrials.gov: RCTICDAS3/2015. CLINICAL SIGNIFICANCE: Minimally invasive approaches for carious lesion management have been promoted. Using sealants for the treatment of microcavitated lesions (ICDAS 3) appears predictable in the routine practice, without predilection for resin or glass ionomer materials. In addition to preserving tooth structure, this strategy reduces chair-time, dental fear and costs, and increases coverage to dental care.

Improvement of Pit-and-Fissure Sealant Bonding to Enamel with Subpressure Treatment.

This research evaluated the effects of subpressure on the shear bond strength (SBS) of 80 specimens with flat enamel surfaces and on AgNO3 microleakage of 40 specimens with flat enamel surfaces and 40 specimens with 1 mm deep cavities before and after thermocycling. The enamel of 168 specimens was grounded to a flat surface. Two types of sealants (E and H) were selected. Sealants were applied to enamel surface (88 specimens, group F) either subjected or not to subpressure. The bonding interfaces were observed using scanning electron microscopy (SEM) and the SBS was examined using a universal testing machine before and after thermocycling. The failure mode was also analyzed. For the microleakage test, 80 specimens were grouped as group A (original enamel flat surface) and group B (a round cavity of 1 mm in depth) (40 per group). Sealants were applied to the teeth either subjected or not to subpressure. The specimens were submitted to a microleakage protocol with AgNO3 and analyzed before and after thermocycling. Statistical analysis was performed for the data. The results showed that subpressure eliminated voids on the interface between the enamel and sealants and significantly enhanced specimens' SBS. Although thermocycling reduced SBS significantly, specimens under subpressure after thermocycling still showed higher SBS than specimens under nonsubpressure before thermocycling. The subpressure groups showed a lower microleakage level compared to nonsubpressure groups, though thermocycling caused deeper silver infiltration. In addition, different sealants showed no significant effect on the SBS and microleakage performance. Overall, subpressure application improves sealant bonding and retention rate and has potential to prevent secondary caries.

Laser versus LED polymerization: Comparison of in vitro preventive sealing procedures.

INTRODUCTION:: The technique of sealing is a widely accepted procedure for prevention of caries. The aim of our in vitro study was to compare the effect of two different curing units (traditional LED source and innovative laser diode lamp) on the integrity of fissure sealant material and its interface with tooth enamel. MATERIALS AND METHODS:: Sixty healthy third molars were randomly assigned to two groups. In group A were teeth intended for polymerization by LED B lamp, and group B comprised teeth to be polymerized by an innovative laser diode. Both groups were treated with the traditional sealing technique, subjected to a metallization process, and analyzed by scanning electron microscope. RESULTS:: Micro-gaps between the sealant and the enamel were found in specimens in both A (43%) and B (40%) groups ( p=0.793), and sealant shrinkage was seen. Significant differences between the groups emerged in the percentage of perimetric micro-erosion sites (80% vs. 100%, p=0.010) and the presence of holes and micro-bubbles on the sealant surface (21% vs. 63%, p=0.001). CONCLUSIONS:: Although macroscopic clinical polymerization occurred with both instruments, the microscopic evaluation showed significant differences between the studied groups in terms of perimetric micro-erosion sites and micro-bubbles, which were higher in laser-cured samples.

Dental Sealants Part 4: Bisphenol A: What dentists should know.

BACKGROUND: Bisphenol A (BPA) is a synthetic chemical resin used worldwide to produce plastic products. It is also a component of the bisphenol A diglycidylether methacrylate (Bis-GMA), which is a monomer found in dental resin-based materials (including resin-based dental sealants, RBSs). The controversy about its possible toxicity begins around the early '30s. Even if the amount of BPA released by dental sealants is well below the limit proposed by the U.S. Environmental Protection Agency and the European Food Safety Authority, we can reduce the risk of exposure, particularly for children, following precautionary measures.

Effects of different resin sealing therapies on nanoleakage within artificial non-cavitated enamel lesions.

The aim of this study was to evaluate nanoleakage within the different lesion-sealing therapies applied to artificial non-cavitated enamel lesions. Thirty-two human anterior teeth were used. Artificial subsurface enamel lesions were produced on the labial surfaces of teeth. The specimens were then randomly divided into three groups (n=10): Group I- Clinpro Sealant application; Group II- ExciTE F adhesive resin application; and Group III- ICON resin infiltrant application. Each group was further divided into two subgroups: control and thermocycler. Nanoleakage was calculated by the digital image analysis software. In the control and thermocycled groups, there was no statistically significant difference between the Groups I, II, and III (p>0.05). The only significant leakage scores were obtained between the Group III control and thermocycler groups (p=0.027). ICON infiltrant can be used as an alternative to dental adhesives and fissure sealants in the sealing of initial non-cavitated enamel lesions. But the resin may become more affected by the water sorption than other resin materials over time. More studies are needed to evaluate long-term durability of resin infiltrants.

Qualitative analysis of dental material ingredients, composite resins and sealants using liquid chromatography coupled to quadrupole time of flight mass spectrometry.

Since 2011, the World Health Organization has encouraged a global phase-down of the use of dental amalgam and actively supported the use of alternative, resin-based dental materials. The resins consist of (meth)acrylate monomers derived from Bisphenol A (BPA), such as Bisphenol A glycidyl methacrylate (BisGMA) and Bisphenol A ethoxylate methacrylate (BisEMA) or triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) which lack the BPA backbone. Besides monomers, other compounds such as photoinitiators and stabilizing agents can be present in the dental resin matrices. The current study consists in the development of an analytical method for the separation and identification of dental material components using LC-QTOF-MS. The developed method was applied on several dental material ingredients, unpolymerized composite resins, and a common dental sealant. The acquired high resolution accurate-mass data was analyzed using suspect screening with an in-house developed library. Next to the main components, various isomers and impurities related to the production of the main component have been detected and identified in the dental material ingredients. In total, 39 chemicals have been identified in the analyzed dental materials. On average 15 chemicals have been identified. Major components, such as BisEMA, BisGMA and TEGDMA were identified although they were not always stated in the material safety data sheets. Minor components included photoinitiators, such as ethyl 4-dimethyl aminobenzoate (EDMAB) and (meth)acrylates impurities originating from production of main ingredients.

Investigation of the chemical profile and cytotoxicity evaluation of organic components eluted from pit and fissure sealants.

The aim of this study was to identify organic components eluted from five resin dental sealants using gas chromatography and mass spectrometry (GC/MS) after 1-day and 40-days storage and the effect of sealants on cell survival of cultured fibroblasts. Five resin materials were studied: BeautiSealant (SHOFU), Clinpro (3M/ESPE), Conseal F (SDI), Grandio Seal (VOCO) and Helioseal Clear (Ivoclar/Vivadent). The organic monomers detected were butylated hydroxytoluene (BHT), bis-phenol-A (BPA), camphoroquinone (CQ), diethylenglycoldimethacrylate (DEGDMA), 4N, N-dimethylaminobenzoic acid butylethoxyester (DMABEE), hydroxyethylmethcrylate (HEMA), hydroquinone monomethylether (MEHQ), triethylene glycol dimethacrylate (TEGDMA), tetrabutylammonium tetrafluoroborate (TBATFB), triphenylstibane (TPSb). The main monomer detected was TEGDMA, whereas BHT and DEGDMA were detected at lower concentrations. Higher monomer concentrations were detected after 40 days storage. The eluting chemical profiles of the tested materials differ qualitative and quantitative. For cytotoxicity evaluation, NIH/3T3 cells were exposed to eluates of sealants and cell viability was assessed by a quantitative technique at two observation periods. Decreased cell viability was observed. The cytotoxicity and the release of monomers from dental materials examined depends on the type of material and the observation time point. Resin-based dental materials have raised public concerns regarding possible adverse biological effects, thus it is essential to evaluate possible side effects for human health.

Dental Sealants Part 3: Which material? Efficiency and effectiveness.

Determining the best choice between the different sealant materials might be complicated. The products that dentists can choose have different properties, such as caries' preventive effect, fluoride release and retention rate. According to the literature, fissure sealant materials fall into two main categories: resin-based sealants and glass ionomer sealants. Even if the "fluoride-releasing resin sealants" are better than "glass ionomer", with regards to retention of the material, the literature shows that their effectiveness in preventing fissure caries in permanent molars does not differ significantly over 24 months.

Assessing abrasion of orthodontic surface sealants using a modified ophthalmic optical coherence tomography device.

OBJECTIVE: Optical coherence tomography (OCT) is a clinical standard in ophthalmology. Currently, its application in dentistry is gaining increasing interest. In this study, we tested the possibility to use a modified commercially available spectral domain OCT (SD-OCT) to assess the layer thickness of orthodontic surface sealants. MATERIALS AND METHODS: Reference samples of surface sealants for calibration and repeatability testing were measured using a micrometer screw. SD-OCT measurements were compared with micro-CT and light microscopic analyses. After validating the calibration of the SD-OCT, surface sealant layer thickness after aging (thermo cycling) and simulation of professional tooth cleaning (PTC) was assessed using the SD-OCT on 45 extracted teeth assigned to three test groups (n = 15 each): Light Bond™ Sealant, Pro Seal®, and Opal® Seal. RESULTS: SD-OCT showed excellent repeatability and accuracy for measurements of surface sealant layer thickness. Compared with micro-CT, SD-OCT showed better accordance with the reference measurements. The analysis of surface sealants after thermo cycling and PTC revealed poor resistance of Light Bond after only aging and demonstrated substantial wear of all sealants after aging and PTC. CONCLUSION: Imaging using commercially available ophthalmic SD-OCT might represent a suitable non-invasive methodology for longitudinal assessments of surface sealant layer thickness in vitro and in vivo. CLINICAL RELEVANCE: SD-OCT might be a suitable non-invasive method for longitudinal assessments of surface sealant durability in clinical trials.

Comparison of resin-based and glass ionomer sealants with regard to fluoride-release and anti-demineralization efficacy on adjacent unsealed enamel.

This study compared resin-based and glass ionomer sealants with regard to their fluoride-release behavior and anti-demineralization potential on adjacent unsealed enamel surfaces. Sealant cavities prepared on bovine enamel blocks were filled with fluoride-containing resin sealants [TeethmateF-1 (TF), ClinproTM (CP)], and glass ionomer sealant [Fuji VII (FVII)]. Specimens were then incubated in artificial saliva for 14 days to measure fluoride. Thereafter, demineralization was performed for 10 days, and the anti-demineralization efficacy was assessed by Swept Source Optical Coherence Tomography (SS-OCT), and cross-sectional nanohardness. All data were statistically analyzed by using ANOVA. FVII exhibited the highest fluoride release. SS-OCT and nanohardness findings indicated that anti-demineralization efficacy of TF was the greatest, whereas FVII was not significantly different from that of CP. Resin sealants released a lower amount of fluoride but exhibited anti-demineralization effects on the adjacent unsealed enamel surfaces that were comparable to that of a glass ionomer sealant.

Shear bond strength and microleakage of a new self-etch adhesive pit and fissure sealant.

This study aimed to evaluate the shear bond strength (SBS) and microleakage of a new self-etch adhesive-based fissure sealant (EG) on aprismatic enamel in comparison to conventional fissure sealing with 30 s acid etching (CG). The fissures were sealed according to the manufacturer's instructions. Each group was divided into 3 subgroups: 1-day water storage, 3-month water storage, and 5,000× thermocycling. After measuring SBS using the Ultradent method, failure mode was analyzed. In additional 16 teeth, microleakage was tested using dye penetration method. Pairwise comparisons were analyzed using Mann-Whitney U-Test. Multiple linear regression was performed to assess the factors influencing on SBS. EG had significantly lower mean SBS (4.1 MPa±2.1) than the CG (17.6 MPa±6.4). CG (1.1%) performed significantly better than the EG (12.8%) in microleakage analysis. The tested EG yielded significantly inferior results and its clinical use should be decided after weighing its pros and cons.

Effect of Er:YAG laser enamel conditioning and moisture on the microleakage of a hydrophilic sealant.

For a given sealant, successful pit and fissure sealing is principally governed by the enamel conditioning technique and the presence of moisture contamination. A new generation of hydrophilic resin sealants is reported to tolerate moisture. This study investigates the impact of Er:YAG laser pre-conditioning and moisture contamination on the microleakage of a recent hydrophilic sealant. Occlusal surfaces of extracted human molars were either acid etched (n = 30), or successively lased and acid etched (n = 30). Ten teeth from each group were either air-dried, water-contaminated, or saliva-contaminated prior to sealing with UltraSeal XT® hydro™. Samples were inspected for penetration of fuchsin dye following 3000 thermocycles between 5 and 50 °C, and the enamel-sealant interfaces were observed by scanning electron microscopy (SEM). Significant differences in microleakage were evaluated using the Mann-Whitney U test with Bonferroni adjustment (p = 0.05). Laser pre-conditioning significantly reduced dye penetration irrespective of whether the enamel surface was moist or dry. Microleakage of water-contaminated acid etched teeth was significantly greater than that of their air-dried or saliva-contaminated counterparts. SEM analysis demonstrated good adaptation in all groups with the exception of water-contaminated acid etched teeth which exhibited relatively wide gaps. In conclusion, this hydrophilic sealant tolerates the presence of saliva, although water was found to impair its sealing ability. Laser pre-conditioning significantly decreases microleakage in all cases.

Evaluation of the influence of time and concentration of sodium hypochlorite on the bond strength of glass fibre post.

This study evaluated the effect of time and concentrations of sodium hypochlorite on the bond strength of a glass fibre post cemented in a root canal with resin cement. A total of 45 single-rooted extracted human teeth were prepared with Protaper® universal files, randomly allocated into nine groups and then subjected to 1% or 4% NaOCl for a period of 1 min or 2 min. Fibre posts were then bonded into the root canal, sectioned and the bond strength tested using a push-out test. A longer irrigation time resulted in a significant reduction (P < 0.05) in bond strength, while a final additional irrigation with distilled water significantly reduced bond strength. The concentration of NaOCl did not significantly affect bond strength. Within the limitations of this study, it was observed that regardless of the concentration of NaOCl used, shorter irrigation times favoured better fibre post bonding.

Microleakage and penetration depth of different fissure sealant materials after cyclic thermo-mechanic and brushing simulation.

The aim of the study was to evaluate microleakage and the penetration-depths of different fissure-sealant materials applied with/without enameloplasty after cyclic aging. One-hundred-sixty mandibular molars were divided into non-invasive and enameloplasty preparation groups and eight material subgroups, including: flowable composites (microhyrid, nanohybrid, and nanofilled), three resin-based (unfilled, filled, and highly-filled), a giomer-based, and a glass-ionomer-based fissure sealant. Specimens were subjected to two-year cyclic chewing and brushing simulation. After 5% basic-fuchsin dye penetration, specimens were sectioned and scored under stereomicroscope. Kruskal-Wallis statistical data showed that preparation type significantly affected the penetration of all tested materials (p<0.05), but not significantly affected microleakage (p>0.05). Flowable composites showed the best and the glass-ionomer-based sealant showed the worst penetration and microleakage. Slight preparation of fissures is not important in microleakage. However, enameloplasty significantly enhanced the depth of penetration of the sealants. Flowable composites offer promising results at the fissure sealing.

Assessment of monomer release from 3 different fissure sealants.

BACKGROUND: Light-activated resin-based dental fissure sealants are the most widely accepted among clinicians. The objective of this study was to determine monomer release of 3 different light-curing fissure sealants in vitro: Control Seal (Voco, Germany), Fissurit FX (Voco, Germany) and R&D Series Fissured Nova (Imicrly, Turkey). METHODS: Each material was polymerized with a curing light: Valo Cordless (Ultradent) LED in standard mode for 20 seconds (n = 27) and 40 seconds (n = 27) and in Xtra power mode (plasma arc) for 3 seconds (n = 27). High-performance liquid chromatography (HPLC) was used to measure the amount of monomers released over 1, 3 and 7 days. RESULTS: Plasma arc groups showed the highest release of monomers at 1, 3 and 7 days in the 3 fissure sealant groups (p<0.001). The greatest release of bisphenol A glycidyl methacrylate (bis-GMA) determined for R&D Series Fissured Nova both with LED 20 seconds and LED 40 seconds and for Control Seal was with the plasma arc. With time, release of the monomer was reduced for all polymerization systems. CONCLUSIONS: Efficiency of the polymerization system and applying the recommended curing time for light-activated resin-based dental materials are very important to protect the patient from potential hazards of residual monomers.