Titanium dioxide nanotubes added to glass ionomer cements affect S. mutans viability and mechanisms of virulence.

This in vitro study evaluated the impact of TiO2 nanotubes (n-TiO2) incorporated into glass ionomer cement (GIC) on Streptococcus mutans (S. mutans) characteristics at cellular and molecular levels. n-TiO2, synthesized by the alkaline method (20 nm in size), was added to Ketac Molar EasyMix® at 0%, 3%, 5%, and 7% by weight. S. mutans strains were cultured on GIC disks with addition or not of n-TiO2 for 1, 3, and 7 days and the following parameters were assessed: inhibition halo (mm) (n=3/group); cell viability (live/dead) (n=5/group); cell morphology (SEM) (n=3/group); and gene expression by real-time PCR (vicR, covR, gtfB, gtfC, and gtfD) (n=6/group). The data were analyzed by the Kruskal-Wallis test, repeated-measures ANOVA or two-way ANOVA, and Tukey's and Dunn's post-hoc tests (α=0.05). The agar diffusion test showed a higher antibacterial property for 5% n-TiO2 compared with 3% and 7% (p<0.05) with no effect of time (1, 3, and 7 days). The cell number was significantly affected by all n-TiO2 groups, while viability was mostly affected by 3% and 5% n-TiO2, which also affected cell morphology and organization. Real-time PCR demonstrated that n-TiO2 reduced the expression of covR when compared with GIC with no n-TiO2 (p<0.05), with no effect of time, except for 3% n-TiO2 on vicR expression. Within-group and between-group analyses revealed n-TiO2 did not affect mRNA levels of gtfB, gtfC, and gtfD (p>0.05). Incorporation of n-TiO2 at 3% and 5% potentially affected S. mutans viability and the expression of key genes for bacterial survival and growth, improving the anticariogenic properties of GIC.

Workflow of digitally guided direct composite resin restorations using ?open source software and 3D printing: a clinical technique.

Objective: To describe how to perform, in a simple manner, a digital wax-up with ?open source software for a clinical application involving direct ?composit?e resin restorations. Report: The clinical technique described presents a simple and highly predictable way of performing direct restorations with the help of a digital wax-up made with ?open source software. ?It uses an open source digital tooth library? to reestablish a more harmonious smile architecture, specifically of teeth that were worn due to parafunction, and restored with direct composite resin restorations.
Conclusions: Thanks to the technology that was used in this case, fast, affordable and accurate results c?ould be obtained. In addition, digital files can be stored, saving material, time, and space, and allowing identical replication of the work either virtually or printed at any time, if needed. (Quintessence Int 2021;52:104-110; doi: 10.3290/j.qi.a45426)

Titanium dioxide nanotubes added to glass ionomer cements affect S. mutans viability and mechanisms of virulence

Abstract This in vitro study evaluated the impact of TiO2 nanotubes (n-TiO2) incorporated into glass ionomer cement (GIC) on Streptococcus mutans (S. mutans) characteristics at cellular and molecular levels. n-TiO2, synthesized by the alkaline method (20 nm in size), was added to Ketac Molar EasyMix® at 0%, 3%, 5%, and 7% by weight. S. mutans strains were cultured on GIC disks with addition or not of n-TiO2 for 1, 3, and 7 days and the following parameters were assessed: inhibition halo (mm) (n=3/group); cell viability (live/dead) (n=5/group); cell morphology (SEM) (n=3/group); and gene expression by real-time PCR (vicR, covR, gtfB, gtfC, and gtfD) (n=6/group). The data were analyzed by the Kruskal-Wallis test, repeated-measures ANOVA or two-way ANOVA, and Tukey's and Dunn's post-hoc tests (α=0.05). The agar diffusion test showed a higher antibacterial property for 5% n-TiO2 compared with 3% and 7% (p<0.05) with no effect of time (1, 3, and 7 days). The cell number was significantly affected by all n-TiO2 groups, while viability was mostly affected by 3% and 5% n-TiO2, which also affected cell morphology and organization. Real-time PCR demonstrated that n-TiO2 reduced the expression of covR when compared with GIC with no n-TiO2 (p<0.05), with no effect of time, except for 3% n-TiO2 on vicR expression. Within-group and between-group analyses revealed n-TiO2 did not affect mRNA levels of gtfB, gtfC, and gtfD (p>0.05). Incorporation of n-TiO2 at 3% and 5% potentially affected S. mutans viability and the expression of key genes for bacterial survival and growth, improving the anticariogenic properties of GIC.

Physical-Mechanical Properties of Bulk Fill Composites Submitted to Biodegradation by Streptococcus mutans.

The aim of this study was to evaluate the Streptococcus mutans biofilm influence on the roughness (Ra), gloss (GU), surface hardness (KHN) and flexural strength (FS) of high viscosity bulk fill composites. Filtek Bulk Fill (FBF), Tetric N Ceram Bulk Fill (TNC), X-tra fil Bulk Fill (XF) and Filtek Z350 (FZ) were used. Ten discs of each composite were prepared for Ra, KHN and GU and 20 bars for the FS. After 24 h, specimens were polished and initial analyzes performed. Samples were sterilized and subjected to biodegradation for 7 days and final analyzes performed. Representative samples of each group were evaluated in Scanning Electron Microscope. Data were submitted to ANOVA two factors and Tukey test. XF presented the highest values (p<0.05) of Ra before and after biodegradation (0.1251; 0.3100), and FZ (0.1443) the lowest after biodegradation (p<0.05). The highest GU values (p<0.05) were observed for FZ (71.7; 62) and FBF (69.0; 64.6), and the lowest (p<0.05) for TNC (61.4; 53.3) and XF (58.5; 53.5), both before and after biodegradation. For KHN the highest values were obtained by XF (151.7; 106), and the (p< 0.05) lowest values for TNC (62.2; 51.8), both before and after biodegradation. The highest values (p<0.05) of FS were observed for FZ (127.6) and the lowest (p<0.05) for TNC (86.9); after biodegradation, XF (117.7) presented the highest (p<0.05) values compared to TNC and FZ." In conclusion, biodegradation increased Ra and decreased GU and KHN for all. Concerning FS, degradation provided a significant decreased value only for FZ.

Surfactin application for a short period (10/20 s) increases the surface wettability of sound dentin.

The aim of this study was to evaluate the effect of spreading the lipopeptide surfactin, for short time (10/20 s), on dentin wettability. Study groups were surfactin: 2.8; 1.4; 0.7; 0.35; and 0.175 mg/mL and a control group that received no treatment. Dentin discs (4 mm height) were prepared and polished with 600-grit SiC paper. Contact angle determinations were carried out after microbrush spreading of surfactin on dentin specimens for, respectively, 10 and 20 s. Excess liquid was removed, and after 60 s, the specimens were analyzed in a goniometer using the sessile drop method to measure the contact angle. Results were analyzed by two-way ANOVA (concentration × time) and t student, with α = 0.05. Lower contact angles were obtained for surfactin (0.7 mg/mL) spread for 10 s. However, no statistical difference was observed for surfactin (2.8 mg/mL) applied during 20 s. Higher contact angles were observed for surfactin (0.7 mg/mL) spread for 20 s. In conclusion, dentin wettability is dependent on spreading time and surfactin concentration.

Enhancing bond strength on demineralized dentin by pre-treatment with selective remineralising agents.

Bonding to demineralized dentin of a diseased tooth has shown to be a significant clinical issue. This study evaluated the effect of 0.2% NaF-(NaF), MI Paste™-(CPP-ACP) and the self-assembling peptide 'P11-4' (Ace-QQRFEWEFEQQ-NH2) contained in Curodont™ Repair, have on microtensile bond strength-(µTBS) of two different adhesive systems (Adper™ Single Bond-(SB) or Clearfil™ SE Bond (CSE)) and wettability of demineralized dentin slices after remineralising agents were applied. The highest µTBS were found for the demineralized dentin-(DD) treated with CPP-ACP; both adhesives systems (p < 0.05) did not significantly difference from P11-4 treatment associated with SB, and also presented higher values than sound dentin-(SD/SB) (p < 0.01). DD treated with P11-4 associated with CSE did not differ from DD/CSE (p > 0.05). The NaF treatment associated with CSE recovered the bond strength values of SD/CSE and associated with CSE demonstrated lower µTBS than other groups, although significantly higher than DD (p < 0.05). P11-4 and CPP-ACP increased significantly the wettability of demineralized dentin (p < 0.05); etching acid improved wettability for all groups (p < 0.05), whilst NaF did not affect the wettability of demineralized dentin (p > 0.05). Morphological analysis of the dentin surface and dentin-resin interface revealed unique features of the applied remineralizing agent. The results indicated that self-assembling peptide P11-4 associated with SB and CPP-ACP associated with SB or CSE significantly enhanced the bond strength to demineralized dentin (p < 0.05). We conclude that by modifying the dentine surface and restoring conditions found on sound dentin, this can enhance the interfacial bonding.

In vitro effect of S. mutans biofilm on fluoride/MDPB-containing adhesive system bonded to caries-affected primary dentin.

PURPOSE: To evaluate the effect of storage in S. mutans culture or water on the durability of fluoride and MDPB-containing adhesive system on artificial caries-affected primary dentin. METHODS: Dentin flat surfaces of primary molars were submitted to artificial caries development using S. mutans biofilm. CAPD cavities were restored with Adper Scotchbond Multi-Purpose (SBM) or Clearfil Protect Bond (CPB) and they were serially sectioned into sticks (1 mm2 cross-sectional area) and stored in S. mutans biofilm for 3 days, in deionized water for 3 months and afterwards subjected to microtensile bond strength (µTBS) test. A control group was submitted to immediate TBS testing. Two-way ANOVA and Tukey's tests were used. Failure sites were observed by SEM and classified as cohesive (dentin or resin) and adhesive failures. RESULTS: The control group showed the highest µTBS values (MPa) for both SBM (25.2 ± 8.5) and CPB (15.6 ± 6.1) adhesive systems. A significant decrease in µTBS values after S. mutans biofilm and water storage was observed for SBM (18.7 ± 5.7 and 17.4 ± 4.1, respectively) and CPB (13.9 ± 5.2 and 13.7 ± 4.8, respectively), but no difference was found between them. The highest percentage of adhesive failure was observed for all groups. However, cohesive failure in dentin was observed in a higher percentage for SBM than CP.