dental materials 35(S1) (2019) e1–e49 e11 Table 1 – The results of color and gloss. Group Color on coated glass Color on shade guide (C4) Color on coated shade guide Difference before and after application on coated shade guide Gloss (GU) L b L b L b L b E A 77.59 ± 0.43 a 7.85 ± 0.65 a 43.46 7.61 75.8 ± 2.20 a 9.21 ± 2.83 a 32.43 ± 2.20 a* 1.60 ± 2.83 a 32.84 ± 2.29 a 0.7 ± 0.5 a B 68.85 ± 0.39 b 6.56 ± 0.57 a 68.35 ± 0.75 b 8.63 ± 0.60 a* 14.13 ± 8.37 b* 1.02 ± 0.60 a 25.63 ± 0.72 bc 5.1 ± 1.1 bc C 75.31 ± 0.40 c 6.46 ± 0.47 a 76.11 ± 0.57 a 9.47 ± 1.17 a* 32.65 ± 0.57 a* 1.86 ± 1.17 a 33.27 ± 0.62 a 2.8 ± 0.9 acd D 66.16 ± 0.78 d 2.21 ± 0.80 b 70.81 ± 0.39 b* 6.83 ± 0.57 a* 27.35 ± 0.39 a* -0.77 ± 0.56 a 27.82 ± 0.40 bd 4.5 ± 0.5 bde* E 89.78 ± 0.86 e 8.64 ± 0.54 c 76.88 ± 1.57 a* 16.24 ± 0.42 b* 33.43 ± 1.58 a* 8.64 ± 0.42 b* 34.54 ± 1.62 a 2.4 ± 0.2 adf* F 68.60 ± 0.27 b -13.20 ± 0.23 d 67.83 ± 0.16 b* -8.51 ± 0.73 c* 24.37 ± 0.15 ab* -16.12 ± 0.73 c* 29.27 ± 0.30 acd 4.6 ± 0.6 bdf* Asterisk marks mean statistical significance between before and after application on coated specimen within each group (p< 0.05). And the same lowercase letter indicates no differences among the groups (p >0.05). Results: L values of A, C and E group ranged from 75.31 to 89.78, gloss values ranged from 0.7 to 2.8. Otherwise, L values of B, D and F group ranged from 66.16 to 70.81, gloss values exhibited between 4.5 and 5.1. It was high values when com- pared with before. L value after applied tooth manicure was significantly increased in all groups and b values differed the most in the between E and F group. Also, E values ranged from 25.63 to 34.54. The setting time was within in the one minute in all groups. The retention rate was ranged from 99.54 to 99.69%. Tooth manicure applied on the tooth surface was not removed after 3 minutes under 150 g pressure. It needs to modify for removing tooth manicure remained on the tooth surface Table 1. Conclusions: In this study, we tried to evaluate the vari- able efficacy of tooth manicure. It is expected the baseline data of evaluation method and safety of consumers can be established by suggesting the guideline of the tooth manicure efficacy testing. Also, these results will be used as a good tool of the tooth manicure efficacy testing. https://doi.org/10.1016/j.dental.2019.08.021 21 Effect of an experimental etchant on dentin bond-strength over time A. Comba 1,∗ , T. Maravic 1 , E. Mancuso 1 , S. Ribeiro Cunha 1,2 , E. Mayer-Santos 1,2 , M. Cadenaro 3 , A. Mazzoni 1 , L. Breschi 1 1 University of Bologna 2 University of Sao Paolo, Brazil 3 University of Trieste Purpose/aim: Dentin demineralization with phosphoric acid greatly depends on its concentration and contact time. To address this issue, a novel, self–limiting etchant has been developed. The aim of this study was to investigate, using micro–tensile bond strength test (TBS) and nanoleakage the performance of an experimental etchant as an alternative to conventional etching of the dentin immediately and over time. Materials and methods: Non–carious teeth (N = 8 per group) were cut to expose middle/deep dentin, assigned to 4 groups and treated according to the manufacturers’ (Ivoclar Vivadent) instructions: G1: dentin was etched with the experimental etching gel and bonded with Adhese Universal (AU); G2: dentin was etched with phosphoric acid gel and bonded with AU (AU control); G3: dentin was etched with the experimental etching gel and bonded with ExciTE F (ExF). G4: dentin was etched with phosphoric acid gel and bonded with ExF (ExF control). Half of the specimens were further subjected to TBS and stressed until failure at baseline, while the second half was aged for 12 months in artificial saliva at 37 ◦ and then stressed until failure. Additional 3 teeth per group were prepared for nanoleakage analysis and the amount of silver-nitrate within the hybrid layer was evaluated using light microscopy both at T = 0 and T = 12. Results: The tree–way Anova test showed that the adhesive system, and the etchant, as well as time significantly influ- enced the results (p< 0.05). Bond strength was significantly higher with the experimental etching gel compared to the con- trol group when AU bond was used. AU showed significantly higher bond strength than the ExF when associated with the experimental etchant. Finally, independently from the adhe- sive procedures, time negatively affected bond strength. There were no differences in the nanoleakage expression between the tested groups. Conclusions: The experimental etchant seems to have a positive influence on resin–dentin bond strength immediately and over time. Hence, the experimental etchant could be rec- ommended as a novel, safe and efficient demineralization technique in the every–day clinical practice. However, further studies on long–term influence of the novel etchant on bond strength are required. https://doi.org/10.1016/j.dental.2019.08.022 22 Effect of Er,Cr:YSGG laser conditions on debonding ysz ceramic L.R. Corby ∗ , D.S. Remley, D.M. Hutto, K.S. Jodha, J.A. Griggs, L. Contreras, S.M. Salazar Marocho University of Mississippi Medical Center, Jackson, USA Purpose/aim: High–speed diamond burs are traditionally used for crown removal, but the polycrystalline nature of yttrium–stabilized zirconia (YSZ) ceramics makes this process time–consuming, expensive and uncomfortable for patients.