Effect of deep margin elevation on fracture resistance of premolars restored with ceramic onlay: In vitro comparative study.

Background: This in vitro comparative study aimed to compare the influence of two levels of deep margin elevation (2 and 3 mm) with either bulk-fill flowable composite or short fiber-reinforced flowable composite on the fracture resistance of maxillary first premolars restored with ceramic onlays. Material and Methods: Fifty sound-extracted maxillary first premolar teeth were selected to prepare mesio-occluso-distal cavities with standardized dimensions. The cervical margins were extended 2 mm below the cemento-enamel junction on both mesial and distal sides. These teeth were randomly divided into five groups: Group I: no box elevation (control group). Group II: 2 mm marginal elevation with bulk-fill flowable composite. Group III: 2 mm marginal elevation with short fiber-reinforced flowable composite. Group IV: 3 mm marginal elevation with bulk-fill flowable composite. Group V: 3 mm marginal elevation with short fiber-reinforced flowable composite. After cementation, all teeth were subjected to a fracture resistance test using the universal testing machine, and the mode of failure was analyzed using a digital microscope at 20x magnification. Results: The result showed a non-significant difference in the fracture resistance between 2 and 3 mm marginal elevation (p>0.05) with respect to each restorative material used for deep margin elevation. However, the fracture resistance of teeth elevated with short fiber-reinforced flowable composite was significantly higher than those elevated with bulk-fill flowable composite at both levels 2 and 3 mm, p=0.041 and 0.038 respectively. Conclusions: The fracture resistance of premolars restored with a ceramic onlay was not influenced by the levels of deep margin elevation (2 or 3 mm). However, marginal elevation with short fiber-reinforced flowable composites provided higher fracture resistance than those elevated with bulk-fill flowable composites, and those without marginal elevation. Key words:Fracture Resistance, Short fiber reinforced flowable composite, Bulk-fill flowable composite, Ceramic onlay, Cervical margin elevation.

Comparison of different bioglass applications on root caries - A laboratory-based study.

The aim of this in-vitro study was to assess the effect of bioglass with different concentrations on root caries. Ninety freshly-extracted teeth with root caries were randomly assigned to a single-use prophylaxis paste containing 15 % bioglass for 30 s with 1,450 ppmF toothpaste (15 % bioglass, n = 30), 1,450 ppmF toothpaste with 5 % bioglass (5 % bioglass, n = 30), and toothpaste containing 1,450 ppmF (Control, n = 30). Each sample received a standard brushing procedure for 10 s twice a day using the toothpastes. Teeth were immersed in remineralising solution with pH of 7 at 37 °C for 720 h. Surface roughness (Ra) was measured at baseline and after the application of the products at 0.5, 1, 4, 12, 24, 48, 168, 336 and 720 h. Subsequently, three samples from each group were randomly selected to measure calcium ion release over 15 h immersion in deionised water. These samples were then analysed using the SEM for the qualitative assessment of lesion topography. Repeated measures ANOVA, Wilcoxon paired tests and percentage changes were carried out to assess Ra. Calcium ion release data was analysed using one-way ANOVA and Tukey post-hoc tests. After 720 h, 15 % bioglass had the highest decrease in Ra (Mean-difference = 1.502 µm, p = 0.001), then 5 % bioglass (Mean-difference = 0.723 µm, p = 0.09) whereas the control had the lowest Ra decrease (Mean-difference = 0.518 µm, p = 0.55). The differences in Ra between the groups were highly significant (p < 0.001). The cumulative calcium ion release was significantly high for the 5 % bioglass in comparison to the 15 % bioglass, whilst the control had the lowest release (p < 0.001). SEM analysis showed the presence of bioglass particles only on 15 % bioglass samples. The use of prophylaxis paste with 15 % bioglass and 1,450 ppmF toothpaste was promising to reverse/arrest root caries when compared to the toothpaste containing 1,450 ppmF with 5 % bioglass for a period of 30 days.

Reversal of Root Caries with Casein Phosphopeptide-Amorphous Calcium Phosphate and Fluoride Varnish in Xerostomia.

Different formulas of topical fluoride have been used to manage root carious lesions. This clinical trial aimed to investigate the efficacy of a dental varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride compared with fluoride alone in reversing/arresting root caries in xerostomic patients over 1 year. A total of 80 patients (age range 45-92 years) with primary root caries (n = 184 root carious lesions) and unstimulated salivary flow rate of <0.2 mL/min were randomly allocated to receive either dental varnish containing CPP-ACP and 5% fluoride (group 1: MI varnish; GC, Japan) (n = 41, 83 lesions), or dental varnish with 5% fluoride alone (group 2: NUPRO White; Dentsply, USA) (n = 39, 101 lesions). Clinical assessments with Severity Index (SI) for root caries, DIAGNOdent measurements, and varnish application were carried out at baseline, 3, 6, and 12 months. Standard oral hygiene instructions with 1,450 ppm fluoride toothpastes were provided for both groups. After 3 months, 63.9% (n = 46) of root caries in group 1 became hard (SI: 0) compared with 39.3% (n = 35) in group 2 (p < 0.01). After 6 and 12 months, the differences in SI were insignificant (group 1, n = 60, 83.3%) (group 2, n = 66, 74.2%) (p = 0.36), and (group 1, n = 60, 89.6%) (group 2, n = 67, 81.7%, n = 1 soft, 1.2%) (p = 0.29), respectively. In both groups, noncavitated leathery lesions were more likely to become hard when compared to the cavitated root caries. A significant decrease in plaque index, surface roughness, lesion dimension, and DIAGNOdent readings with a significant increase in lesion distance from the gingival margin was reported in both groups (p < 0.05). This study has provided evidence that fluoride dental varnish either with or without calcium and phosphate has the potential to arrest/reverse root caries, especially noncavitated lesions for patients with xerostomia.

A comparative evaluation of ion release characteristics of three different dental varnishes containing fluoride either with CPP-ACP or bioactive glass.

OBJECTIVE: To compare ion release characteristics of three different dental varnishes either containing CPP-ACP and fluoride (CPP-ACPF, MI Varnish GC, Japan), bioactive glass and fluoride (BGAF, Dentsply Sirona USA) or fluoride alone (NUPRO White, Dentsply Sirona USA) using fluoride-Ion Selective Electrode (F-ISE), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), 19F and 31P Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). METHODS: A thin layer (0.0674±0.0005g) of each varnish (20×25mm in area) was spread on a roughened glass slide (n=7). They were separately immersed in 10ml Tris buffer (0.06M, pH=7.30), and changed after 1, 2, 4, 6, 24 and 48h. Fluoride-ion concentration at each time using the F-ISE, whilst calcium and phosphate release were investigated using ICP-OES. XRD, FTIR. MAS-NMR analyses were also performed before and after immersion. RESULTS: The cumulative F-ion release was significantly higher in CPP-ACPF (1.113mmol/g)>BGAF(0.638)>F(0.112) (p<0.001). The cumulative calcium and phosphorus were higher in the CPP-ACPF (0.137mmol/g, 0.119) than BGAF (0.067, 0.015) (p<0.001) respectively. The XRD and 19F MAS-NMR confirmed the presence of NaF peaks in all cases before immersion. There were less prominent signal and appearance of fluorapatite crystals after immersion. 19F MAS-NMR revealed CaF2 formation after immersion in both CPP-ACPF and BGAF. 31P MAS-NMR showed phosphate signals in both CPP-ACPF and BGAF before immersion. FTIR failed to show any signs of apatite formation. SIGNIFICANCE: Both CPP-ACP and bioactive glass enhanced ion release without compromising the bioavailability of fluoride. The CPP-ACPF varnish had the most promising ion release.