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

Study on the mechanical and aging properties of an antibacterial composite resin loaded with fluoride-doped nano-zirconia fillers

Preventing the occurrence of secondary caries serves as one of the significant issues in dental clinic, thus make it indispensable to improving the properties of conventional composite resin (CR) by developing a novel CR. In present study, two groups of experimental CRs loaded with different contents of fluoride-doped nano-zirconia fillers (25 wt% and 50 wt%) were fabricated. The surface topography, mechanical performance, fluoride release, antibacterial effect, aging property and cytotoxicity of the experimental CRs were evaluated subsequently. A uniform distribution of the F-zirconia fillers over the whole surface of resin matrix could be observed. The experimental CRs showed continuous fluoride release within 28 days, which was positively correlated with the content of F-zirconia fillers. Moreover, the amount of fluoride release increased in the acidic buffer. Addition of F-zirconia fillers could improve the color stability, wear resistance and microhardness of the experimental CRs, without reducing the flexure strength. Furtherly, the fluoride ions released continuously from the experimental CRs resulted in effective contact and antibacterial properties, while they showed no cytotoxicity. As a consequence, considerations can be made to employ this new kind of composite resin loaded with fluoride-doped nano-zirconia fillers to meet clinical requirements when the antimicrobial benefits are desired.

Clinical effectiveness of resin-modified glass ionomer-based fluoride varnish for preventing occlusal caries lesions in partially erupted permanent molars: A randomised active-controlled trial

BACKGROUND

Deep pits and fissures in partially erupted permanent molars are vulnerable to dental caries.

AIM

To assess the clinical effectiveness of resin-modified glass ionomer-based fluoride varnish (RMGI-F varnish: Clinpro XT™ varnish) in preventing occlusal caries lesions in partially erupted permanent first molars.

DESIGN

In this randomised active-controlled superiority trial with a single-blind parallel design, 74 children with 182 partially erupted first permanent molars were allocated into two groups: Group 1: RMGI-F varnish; and Group 2: GI sealant (active control), with an application of 0.1% sodium fluoride varnish for all other teeth. The primary outcome was ICDAS score ≥1 at 12 months of follow-up. Data were analysed using adjusted Chi-square test and GEE regression for binary outcomes.

RESULTS

Group 1 (15.7%) and Group 2 (13.8%) did not differ significantly in ICDAS ≥1 scores at 12 months of follow-up (adjusted χ²  = 0.373, p = .541). There was no significant difference in retention between Group 1 (48.3%) and Group 2 (20.7%) at 12 months of follow-up (adjusted χ²  = 0.1, p = .752). Mean application time per tooth (16 ± 5.9 vs 20.2 ± 5.4 min) was significantly different (t = 5.26, p = .014).

CONCLUSIONS

RMGI-F varnish was not superior to GI sealant in preventing occlusal caries lesions in partially erupted molars.

Remineralizing Effects of Resin-Based Dental Sealants: A Systematic Review of In Vitro Studies

The incorporation of remineralizing additives into sealants has been considered as a feasible way to prevent caries by potential remineralization through ions release. Thus, this systematic review aimed to identify the remineralizing additives in resin-based sealants (RBS) and assess their performance. Search strategies were built to search four databases (PubMed, MEDLINE, Web of Science and Scopus). The last search was conducted in June 2020. The screening, data extraction and quality assessment were completed by two independent reviewers. From the 8052 screened studies, 275 full-text articles were assessed for eligibility. A total of 39 laboratory studies matched the inclusion criteria. The methodologies used to assess the remineralizing effect included microhardness tests, micro-computed tomography, polarized-light microscopy, ions analysis and pH measurements. Calcium phosphate (CaP), fluoride (F), boron nitride nanotubes (BNN), calcium silicate (CS) and hydroxyapatite (HAP) were incorporated into resin-based sealants in order to improve their remineralizing abilities. Out of the 39 studies, 32 studies focused on F as a remineralizing agent. Most of the studies confirmed the effectiveness of F and CaP on enamel remineralization. On the other hand, BNN and CS showed a small or insignificant effect on remineralization. However, most of the included studies focused on the short-term effects of these additives, as the peak of the ions release and concentration of these additives was seen during the first 24 h. Due to the lack of a standardized in vitro study protocol, a meta-analysis was not conducted. In conclusion, studies have confirmed the effectiveness of the incorporation of remineralizing agents into RBSs. However, the careful interpretation of these results is recommended due to the variations in the studies’ settings and assessments.

Clinical success of fluoride-releasing fissure sealant in permanent first molars: 5-year retrospective atudy

Background/Aim: It is important to prevent caries on permanent first molars. Fissure sealants are very effective in protecting fissures from caries. The study aimed to determine the clinical success of fluoride-releasing fissure sealants in permanent first molars in the long term. Material and Methods: 64 children with 256 healthy erupted first permanent molars and followed for 5 years, comprised the study. Children who received a fluoride-releasing fissure sealant and came regularly to controls throughout 5 years were evaluated by retention rate and development of new caries and compared with a control group. Results: The complete retention rate of fluoride-releasing fissure sealants was 48.5% and 10.7 % of the sealed teeth had caries after 5 years. 25% of the teeth without fissure sealant were decayed after five years. There was no significant difference between the rate of retention of fissure sealants and the frequency of tooth brushing after 1 year. There was no significant difference between the rate of retention of fissure sealants and oral hygiene status of children after 1 year. Conclusions: The fluoride-releasing fissure sealants were effective for the prevention of caries on pit and fissures of permanent molars and long-term clinical success was satisfying.

Clinical success of fluoride-releasing fissure sealant in permanent first molars: 5-year retrospective study

Background/Aim: It is important to prevent caries on permanent first molars. Fissure sealants are very effective in protecting fissures from caries. The study aimed to determine the clinical success of fluoride-releasing fissure sealants in permanent first molars in the long term. Material and Methods: 64 children with 256 healthy erupted first permanent molars and followed for 5 years, comprised the study. Children who received a fluoride-releasing fissure sealant and came regularly to controls throughout 5 years were evaluated by retention rate and development of new caries and compared with a control group. Results: The complete retention rate of fluoride-releasing fissure sealants was 48.5% and 10.7 % of the sealed teeth had caries after 5 years. 25% of the teeth without fissure sealant were decayed after five years. There was no significant difference between the rate of retention of fissure sealants and the frequency of tooth brushing after 1 year. There was no significant difference between the rate of retention of fissure sealants and oral hygiene status of children after 1 year. Conclusions: The fluoride-releasing fissure sealants were effective for the prevention of caries on pit and fissures of permanent molars and long-term clinical success was satisfying.

Analysis of enamel/restoration interface submitted cariogenic challenge and fluoride release

The treatment of high-risk patients still is a challenge. The understanding and development non-invasive, non-destructive, and non-ionizing techniques, can help to guide the treatment and the diagnosis of primary and recurrent caries. The present study evaluated the behavior of enamel/restoration interface after a cariogenic challenge by Fourier domain optical coherence tomography (FD-OCT), scanning electron microscopy (SEM) examination, and the fluoride release of the different restorative materials. Cavities (1.5 × 0.5 mm) were performed in enamel surface and divided into groups (n = 8): glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), and resin composite (RC). The samples were submitted to pH-cycling, and the solutions analyzed for cumulative fluoride by ion-analyzer. The morphology was analyzed by SEM through replicas. The optical attenuation coefficient (OAC) was calculated through exponential decay from the images generated by FD-OCT. Data were analyzed considering α = 0.05. OAC values increased for all groups after pH-cycling indicating demineralization (p < .05). Considering the remineralizing solution, RMGIC presented higher fluoride release rate, followed by GIC, while RC did not release any fluoride. Yet for the demineralizing solution, RMGIC and GIC released similar fluoride rates, overcoming RC (p < .05). Micrographs revealed no changes on the restorations margins, although enamel detachment was observed for RC and GIC after pH-cycling.

The Potential of a Bioactive, Pre-reacted, Glass-Ionomer Filler Resin Composite to Inhibit the Demineralization of Enamel in Vitro

CLINICAL RELEVANCE

A prereacted, glass-ionomer filler fluoride-containing resin composite had lower remineralization potential than glass-ionomer cements but was able to inhibit enamel demineralization; thus, it may be an option for restoring dental surfaces for patients at high risk of caries.

SUMMARY

Evidence is lacking on the use of surface prereacted glass-ionomer filler resin composites to inhibit demineralization and that simulate real clinical conditions. The present laboratory study evaluated the potential of such composites to prevent demineralization and quantified fluoride (F) and other ions released from restorative materials after a dynamic pH-cycling regimen applied to the tooth material interface in vitro. The pH-cycling regimen was assessed by measuring surface hardness (SH) along with energy dispersive X-ray spectroscopy (EDX).

METHODS AND MATERIALS

Ninety blocks of bovine enamel were subjected to composition analysis with EDX, and were further categorized based on SH. The blocks were randomly divided into 6 treatment groups (n=15 each): F IX (Fuji IX Extra; GC Corporation); IZ (Ion Z, FGM); F II (Fuji II LC, GC Corporation); B II (Beautifil II, Shofu); F250 (Filtek Z250 XT, 3M ESPE); and NT (control, no treatment). The blocks were subjected to a dynamic pH-cycling regimen at 37°C for 7 days concurrently with daily alternations of immersion in demineralizing/remineralizing solutions. EDX was conducted and a final SH was determined at standard distances from the restorative materials (150, 300, and 400 μm).

RESULTS

The EDX findings revealed a significant increase in F concentration and a decrease in Ca2+ in the enamel blocks of group B II after the pH-cycling regimen (p<0.05). SH values for groups F IX, IZ, and F II were greater than those for groups B II, F250, and NT at all distances from the materials.

CONCLUSIONS

The results suggest that each of 3 restorative materials, F IX, IZ, and F II, partially inhibited enamel demineralization under a dynamic pH-cycling regimen.

Assessment of Demineralization Inhibition Effects of Dentin Desensitizers Using Swept-Source Optical Coherence Tomography

The purpose of this study was to evaluate the mechanism of action and the inhibiting effects of two types of desensitizers against dentin demineralization using pre-demineralized hypersensitivity tooth model in vitro. In this study, we confirmed that a hypersensitivity tooth model from our preliminary experiment could be prepared by immersing dentin discs in an acetic acid-based solution with pH 5.0 for three days. Dentin discs with three days of demineralization were prepared and applied by one of the desensitizers containing calcium fluoro-alumino-silicate glass (Nanoseal, NS) or fluoro-zinc-silicate glass (Caredyne Shield, CS), followed by an additional three days of demineralization. Dentin discs for three days of demineralization (de3) and six days of demineralization (de6) without the desensitizers were also prepared. The dentin discs after the experimental protocol were scanned using swept-source optical coherence tomography (SS-OCT) to image the cross-sectional (2D) view of the samples and evaluate the SS-OCT signal. The signal intensity profiles of SS-OCT from the region of interest of 300, 500, and 700 µm in depth were obtained to calculate the integrated signal intensity and signal attenuation coefficient. The morphological differences and remaining chemical elements of the dentin discs were also analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. SS-OCT images of CS and NS groups showed no obvious differences between the groups. However, SS-OCT signal profiles for both the CS and NS groups showed smaller attenuation coefficients and larger integrated signal intensities than those of the de6 group. Reactional deposits of the desensitizers even after the additional three days of demineralization were observed on the dentin surface in NS group, whereas remnants containing Zn were detected within the dentinal tubules in CS group. Consequently, both CS and NS groups showed inhibition effects against the additional three days of demineralization in this study. Our findings demonstrate that SS-OCT signal analysis can be used to monitor the dentin demineralization and inhibition effects of desensitizers against dentin demineralization in vitro.