Effect of photo-thermal acceleration on in-office bleaching

Feasibility and Safety of Adopting a New Approach in Delivering a 450 nm Blue Laser with a Flattop Beam Profile in Vital Tooth Whitening. A Clinical Case Series with an 8-Month Follow-Up

A prospective observational case series included six patients who presented with discoloured upper and lower teeth extending from the right second premolar to the left second premolar. The photoactivation dosimetry and treatment protocol were as follows: λ 450 nm, 1 W, CW; flattop beam profile; 1 cm2; 15 J/spot; 10 irradiated spots; an irradiation time of 15 s/spot; three whitening cycles in a single session. Blanc One ULTRA+ was the bleaching agent. A visual analogue scale (VAS) was utilised to evaluate the pain intensity and dental hypersensitivity during treatment immediately after complete treatment (T1), 24 h (T2), and 8 h (T3) postoperatively, and at an 8-month follow-up timepoint (T4), whereas the dental colour shade change was assessed using the VITA colour shade guide pre-treatment (T0), T1, and T4. The Gingival index and modified Wong Baker faces scale were utilised to evaluate gingival inflammation and patients' treatment satisfaction, respectively. Our findings revealed a reduction in the dental colour shade of the six cases between 2 and 10- fold (average of 3.5-fold) at T1 and maintained at T4, indicating significant improvement in the colour shade change with optimal outcomes. The percentage of this improvement for all the patients was ranged between 16.6% and 33.3%. At all timepoints, a "0" score was provided for pain intensity, dental hypersensitivity, and gingival inflammation. Our study demonstrates the feasibility and safety of a λ 450 nm laser delivered with a flattop handpiece to achieve optimal whitening outcomes without adverse effects. This offers a useful guide for dental clinicians for vital in-office tooth whitening. Extensive clinical studies with large data are warranted to validate our study protocol.

Effect of Laser and Conventional Office Bleaching and Polishing on the Color Change of Stained Nanohybrid and Microhybrid Composite Resin

Aim

The present study investigated the effects of laser and conventional in-office bleaching, and polishing on the color of stained composite resin.

Materials and Methods

A microhybrid composite (Clearfil AP-X) and a nanohybrid composite (Grandio) were selected. Twenty-four discs (2 × 10 mm) for each composite were prepared. The samples were immersed in coffee solution (25 g of coffee in 250 mL water) for seven days. Then the samples were divided into three groups (n = 8) and the stains were removed using bleaching (with Opalescence Xtra Boost), diode laser irradiation with Heydent material and a Sof-Lex polishing kit. The L ∗a ∗b ∗ color parameters were determined using a spectrophotometer before and after immersion and after stain removal procedures, and the overall color changes (ΔE) were calculated. The data were analyzed with two-way analysis of variance.

Results

In the Clearfil composite resin group, the mean ΔE compared to the baseline using in-office bleaching, laser irradiation, and Sof-Lex polishing kit were 3.31, 3.35, and 4.93, respectively. These values with the Grandio composite resin were 3.31, 6.35, and 4.57, respectively. The highest capacity to remove stains was related to the conventional in-office bleaching method. Grandio composite resin underwent more color changes than Clearfil composite resin significantly (P-value < 0.05).

Conclusion

Both composite resins exhibited color changes after immersion in the discoloring solution. However, after staining-removing procedures, the ΔE values decreased. Decreases in the ΔE values were not sufficient to restore the color to that before immersion in the discoloring solution with any stain-removing methods.