Toshiki Takamizawa

This study aimed to compare the efficacy of tooth whitening and prevalence of tooth sensitivity between 6% hydrogen peroxide (HP) and 10 % carbamide peroxide (CP) at-home whitening systems. Forty-eight patients were chosen and divided into two groups: 6% HP (Tion Take Home With, WI) and 10% CP (Tion Take Home Platinum, PL). Both groups followed the manufacturer’s instructions. The whitening procedures were performed over a 10 day period of 1 h per day in WI and a 14 day period of 2 h per day in PL. Tooth color changes were measured with a spectrophotometer. The pain intensity was assessed using a numerical rating scale. No significant differences in ΔE*ab, ΔE00, and ΔWID were found between the groups. Tooth sensitivity was more prevalent in WI than in PL. Ten days of 6% HP use was as effective as 14 days of 10% CP.

This study aimed to determine the influence of air abrasion on the shear bond strength (SBS) of universal adhesives when using different abrasive powders. The AquaCare Twin served as the injection device. The prepared bovine dentin specimens were air- abraded with alumina particles or bioactive glass before applying the universal adhesive (All Bond Universal, Clearfil Universal Bond Quick ER, or Scotchbond Universal Plus Adhesive). The resin composite-bonded specimens were stored in distilled water at 37°C for 24 h before measuring the SBS. The roughness and free energy of the adherent surfaces were measured, followed by scanning electron microscopy (SEM) and SEM/Energy dispersive X-ray analyses. Dentin pre-treatment and the adhesives used significantly affected the SBS values (p<0.001). Significant interactions were observed between pre-treatment conditions and the adhesive system (p<0.001). The bond strengths of universal adhesive depended on the surface properties of the dentin and the powder used.

Objective: This clinical study assessed the color stability of combined whitening protocols for up to 2 years when using prefilled at‐home whitening trays during intervals between in‐office whitening sessions.Materials and Methods: In‐office whitening containing 35% hydrogen peroxide was used. A prefilled tray with 6% hydrogen peroxide was used for at‐home whitening. Sixty‐six participants were randomly assigned to three groups: group I, at‐home whitening was performed 10 times between three in‐office whitening sessions; group II, at‐home whitening was performed five times between three in‐office whitening sessions; group III, only in‐office whitening (three sessions) was performed. Tooth color was assessed before whitening treatment and at 1‐day, 3‐month, 6‐month, 1‐year, and 2‐year follow‐ups using a spectrophotometer. The color differences between the color before whitening and at each follow‐up measurement were evaluated based on CIELAB ΔE*_ab, CIE DE2000 ΔE ₀₀, and ΔW _ID.Results: Although the ΔE*_ab and ΔE ₀₀ in all groups gradually decreased over time, the color stabilities vary in different whitening techniques. Groups II and III showed significantly decreased ΔW _ID (p < 0.05) in the early follow‐up periods when compared with that of group I.Conclusions: The use of both in‐office whitening and at‐home whitening using prefilled trays resulted in longer‐lasting whitening efficacy than in‐office whitening alone.

Objectives This study aimed to evaluate the dentin bond performance of various resin luting cement (RLC) systems combined with universal adhesives in different luting strategies. Materials and methods Three self-adhesive resin luting cements (SRLCs) were used with universal adhesives as primers. Twelve specimens per group were prepared to measure shear bond strength (SBS) under distinct luting strategies in etch-&-rinse and self-etch modes. Regarding luting strategies, the bonded specimens were categorized into four groups based on tooth primer application and the curing mode of the SRLC paste: (i) with light irradiation of the tooth primer (wL) + dual-cure mode (DC) of the SRLC paste, (ii) wL + self-cure mode (SC) of the SRLC paste, (iii) without light irradiation of the tooth primer (woL) + DC mode of the SRLC paste, and (iv) woL + SC mode of the SRLC paste. Specimens were also subjected to different storage conditions: 24 h in water (baseline condition) and 10,000 cycles of thermal cycling. Results Luting strategy, storage condition, and SRLC system type significantly influenced dentin SBS values in both etching modes. Notably, certain SRLCs exhibited significantly higher dentin SBS when the primer was light-irradiated compared with no primer irradiation. Conclusion Most SRLCs demonstrated higher dentin bond strength with light-irradiated primers, suggesting potential enhancement of dentin bond performance via primer light irradiation.

Objective: The color matching of single‐shade resin composites after in‐office whitening was investigated.Materials and Methods: Four single‐shade resin composites were used. A total of 35% hydrogen peroxide was used as the whitening agent. The resin composite was placed in a cavity of an artificially discolored bovine tooth. The color differences between the restoration and surrounding enamel before and after whitening were determined based on ΔE*_ab, ΔE₀₀, and ΔWI_D. The color stability, surface roughness (Sa), and surface gloss (GU) of the resin composite alone were also evaluated. Statistical analyses were performed using repeated‐measures analysis of variance with the Tukey–Kramer test.Results: Based on the 50:50% of perceptibility and acceptability thresholds of ΔE*_ab and ΔE₀₀, none of the resin composite restorations were clinically acceptable before or after whitening. Regarding ΔWI_D, although all resin composites showed “acceptable match” in the baseline, they showed “mismatch” after the third session of whitening. Most of the resin composites alone were stable in color against whitening.Conclusions: Although the single‐shade resin composites failed to achieve the expected color matching on discolored teeth either before or after the whitening, the impact of the whitening on the color of the resin composite alone may be negligible.

This study aimed to observe and compare the resin luting cement (RLC)/dentin interfaces of different types of RLC systems with scanning electron microscopy (SEM). This study evaluated six self-adhesive resin luting cement systems (SARLCs), four systems combining a SARLC with a tooth primer (SARLCPs), and six conventional resin luting cement systems (CVRLCs). Cured resin composite rods were bonded to bovine dentin using RLCs in different etching modes. The morphological features at the interfaces were observed using SEM. Although all RLCs in etch-&-rinse (ER) mode showed a clear hybrid layer, most SARLCs had a thinner and more porous hybrid layer than the SARLCPs and CVRLCs. All SARLCPs with primer and CVRLCs showed a thin high-density layer below the primer layer in both etching modes. CVRLCs and SARLCPs with primer treatment systems may be more versatile and reliable when compared to simplified RLC systems.