ABSTRACT
@#Resin-based pit fissure sealants (RBS) are used to prevent occlusal caries in children. The success of RBS in preventing dental caries is largely influenced by its retention on the tooth surface, which is also affected by its physicomechanical properties. The physicomechanical properties of RBS can be enhanced through the addition of fillers. With the advent of nanofillers, the physicomechanical properties were improved without altering RBS flowability. The present study developed an RBS with a 70 wt% resin matrix and 30 wt% nanofillers. The resin matrix consisted of urethane dimethacrylate (55 wt%), triethylene glycol dimethacrylate (45 wt%), camphoroquinone (0.3 wt%), and 2-(dimethylamino) ethyl methacrylate (0.7 wt%). Silane-treated rice husk-derived nanosilica (20 wt%) and nanohydroxyapatite (10 wt%) were added as fillers. Clinpro, Fissurit FX, and an unfilled sealant were controls. All RBS were tested for surface roughness, Vickers hardness, flexural strength, and flowability. Statistical analysis with oneway ANOVA revealed significant differences between groups in surface roughness, hardness, flowability (p < 0.001), flexural strength, and flexural modulus (p < 0.05). Experimental sealants had higher flexural strength (78 MPa) and flow distance (29.05+1.16 mm) than commercial controls.However, the surface roughness of experimental sealants (0.25+0.08 μm) was higher than Clinpro (0.087+0.027 μm) but lesser than Fissurit FX (0.35+0.19 μm). The Vickers hardness of experimental sealants (23+1.63 VHN) was less than Fissurit FX (28.80+1.69 VHN) but higher than Clinpro (21.74+1.68 VHN). This novel RBS had physicomechanical properties comparable to commercial sealants. The use of nanosilica from rice husk makes this pit and fissure sealer sustainable and environmentally friendly in dentistry.
ABSTRACT
Background: 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. Aims: To evaluate if different immersion methods and surface treatments influence the color stability of resin‑based specimens. Methodology: 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. Statistical Analysis: Two‑way ANOVA and Tukey’s post hoc tests (α =0.05). Results: 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. Conclusions: 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.
ABSTRACT
OBJECTIVES: In 2002, the Ministry of Health and Welfare initiated a national sealant program (NSP) in public health centers in order to promote oral health among children in rural areas as well as among children with low socio-economic status in urban areas. However, this program was terminated in 2009 and substituted with the national insurance coverage of sealants (NICS). The aim of this study is to evaluate the impact of the change from NSP to NICS on regional inequality. METHODS: Based on data obtained from the 2010 and 2012 Korea National Oral Health surveys conducted, we analyzed the average number of permanent teeth with sealants (mean sealant) on the first molars and the prevalence of active dental caries in permanent teeth (D rate), segregated by region, in 8-year-old children. Analyses were performed using SPSS 21.0 (SPSS Inc., Chicago, IL, USA) after taking into consideration the complex design of the samples. RESULTS: The D rate of rural children was higher than that of those in metropolitan and city areas. Compared to the 2010 data on the mean sealants on the first molars, a 14.4% and 48.1% increase was observed in the mean sealants in children in the metropolis and in cities in 2012, respectively. However, this number decreased by 7.5% only in the rural areas. CONCLUSIONS: Accessibility to dental services was limited in the rural areas as compared than in other areas; this result is based on the fact that the D rate in rural areas was higher than that in other areas. The NSP has decreased this regional inequality with regard to the accessibility to dental services. However, it was suggested that the mean sealant on the first molars was reversed due to a change from NSP to NICS.