Novel approaches for caries lesion removal and treatment have been proposed. This study evaluates the combined use of an experimental ultrasound, aPDT (antimicrobial photodynamic therapy) and bioactive glasses on the removal, decontamination and remineralization of dentin caries lesions. A biological model created with a duo species biofilm (Streptococcus mutans and Lactobacillus acidophilus) was used for the development of a caries-like lesion over the dentin for 7 days. Bovine dentin specimens (4 × 4 × 2 mm) were randomized according to the following caries removal techniques: bur (BUR) or ultrasound (ULT), decontamination (with or without aPDT) and remineralization materials (45S5 or F18 bioactive glasses). The following different groups were investigated: caries lesion (control); sound dentin (control); BUR; BUR + aPDT; ULT; ULT + aPDT; BUR + 45S5, BUR + F18; ULT + 45S5; ULT + F18; BUR + aPDT + 45S5; BUR + aPDT + F18; ULT + aPDT + 45S5; and ULT + aPDT + F18. Transverse microradiography (TMR), cross-sectional microhardness (CSH), FT-Raman spectroscopy and confocal microscopy (CLSM) were performed. A two-way ANOVA and Tukey’s test were used (α = 0.05). (3) Results: The TMR revealed a lesion depth of 213.9 ± 49.5 μm and a mineral loss of 4929.3% vol.μm. The CSH increases as a function of depth, regardless of the group (p < 0.05). Removal with BUR (24.40–63.03 KHN) has a greater CSH than ULT (20.01–47.53 KHN; p < 0.05). aPDT did not affect the CSH (p > 0.05). No difference was observed between 45S5 or F18 (p > 0.05), but a change was observed for ULT (p > 0.05). The FT-Raman shows no differences for the phosphate (p > 0.05), but a difference is observed for the carbonate and C-H bonds. The CLSM images show that aPDT effectively inactivates residual bacteria. A combination of ULT, aPDT and bioactive glasses can be a promising minimally invasive treatment.

The aim of this study was to evaluate the efficacy of an ultrasound device and the dentin surface morphology after removal of the caries dentin lesions by removal rate and scanning electron microscopy (SEM). The Knoop hardness test on the bovine dentin blocks (n = 20, 4x4x2mm) was performed to standardize the samples and only those with 38 ± 2 KHN were included. The dentin blocks were submitted to induction of artificial caries lesions, using the bacterial model. Strains of Streptococcus mutans and Lactobacillus acidophilus were used for 7 days. The caries dentin lesion was removed for 1 min, according to two methods: G1 - carbide bur under low-speed rotation (control group) and G2 - ultrasound device under refrigeration. For the removal rate, the samples were weighed 3 times: T0 (before induction), T1 (after induction) and T2 (after removal). Morphology evaluation of the residual dentin surface was performed by SEM. Data normality was verified by Shapiro-Wilk test (p ≥ 0.240). T-test for independent samples was applied to evaluate the removal rate. A significance level of 5% was adopted. G2 provided lower removal rate than G1 (G1: 3.68 mg and G2 = 2.26 mg). SEM images showed different morphological characteristics between the groups. G2 showed absent of smear layer, while G1 showed a visible smear layer over the surface. We concluded that ultrasound device provides minimally invasive removal with residual dentin exhibiting open dentin tubules and no smear layer formation and no bacteria, which infer the removal of the infected tissue.

Objective: To evaluate the efficacy and cytotoxicity of in‐office bleaching gels with hyaluronic acid (HA) or carbomer 940 (CAR), titanium dioxide nanoparticles co‐doped with nitrogen and fluorine (NF_TiO ₂ ), and hydrogen peroxide (HP; H ₂ O ₂ ) at 1.5% and 6% with violet LED irradiation. Materials and Methods: 48 bovine enamel/dentin discs (5 × 3 mm) stained with black tea for 24 h were assigned to six groups ( n = 8): HA‐1.5%HP + LED, HA‐6%HP + LED, CAR‐1.5%HP + LED, CAR‐6%HP + LED, 35%HP‐commercial (control), and a negative control (no treatment). The discs were placed in artificial pulp chambers (APCs) and underwent three 30‐min bleaching sessions with 20 violet LED cycles (1‐min activation, 30‐s pause) at 7‐day intervals. Extracts were applied to MDPC‐23 cells, assessing color change (ΔE ₀₀ ), whiteness index (ΔWI _D ), H ₂ O ₂ diffusion, cell viability (CV), oxidative stress (OxS), and cell morphology (SEM). Data were analyzed by one‐way ANOVA and Tukey post hoc test ( α = 0.05). Results: Gels with HA showed no statistical difference in ΔE ₀₀ and ΔWI _D compared with 35%HP‐commercial ( p > 0.05). H ₂ O ₂ diffusion and oxidative stress were lower in 1.5% and 6% HP groups. Cell viability was higher in 1.5% HP groups ( p < 0.05). There were no changes in cell morphology. Conclusion: Bleaching gels with HA, NF_TiO ₂ NPs, low H ₂ O ₂ concentrations, and violet LED irradiation reduced cytotoxicity without compromising efficacy. Clinical Relevance: Experimental bleaching gels with hyaluronic acid, NF_TiO ₂ nanoparticles, low H ₂ O ₂ concentrations, and combined with violet LED irradiation achieve similar efficacy to high‐H ₂ O ₂ gels (35%). This approach also promises to reduce cytotoxic damage, providing a safer in‐office bleaching option.