Whitening Treatment Combined With Bioactive Materials - In Situ Study

Objectives: This study investigated the influence of bioactive materials on whitened surfaces of enamel and dentin; data was analyzed using Knoop hardness test.

Methods: Eight human third molars were sectioned into five wafers each. All wafers had their baseline Knoop Hardness Number (KHN) of enamel (E0) and dentin (D0) measured. Each wafer of the tooth was assigned to a group (n=8). The wafers were mounted in intra-oral palatal retainers, used by 8 volunteers during 24h/day for 14days. The treatments applied in each retainer were: 1: OPF, whitening treatment (WT) with Opalescence PF, 15% carbamideperoxide (CP) (Ultradent); 2: NWA, whitening treatment with NiteWhite ACP, 16% CP (Discus Dental); 3: OPF&Bio (Biosilicate®, Vitrovita) mixed; 4: OPF+BioBiosilicate® applied for 5 minutes once a week after WT; 5: OPF+RelACP, Relief ACP (Discus Dental) applied 30 min per day after WT. The bleaching gels were applied for 8h per day, according to manufacturers’ instructions. Subsequently, KHN were measured for enamel (E1) and dentin (D1).

Results: Final KHN ​​were compared with baseline values. Statistical analysis using Paired t-test (p>0.05) is shown in table below.

Treatment	E0	E1	D0	D1
OPF	281.4 (+-6.5)*	267.8 (+-10.6)*	47.2 (+-6.4)*	38,9 (+-2.4)*
NWA	279.7 (+-4.5)	279.6 (+-10.8)	45,2 (+-7.6)	42.5 (+-7.0)
Opal&Bio	289.1 (+-5.0)	289.6 (+-7.2)	46.4 (+-8.1)	44.3 (+-4.3)
Opal+Bio	279.3 (+-9.2)*	265.8 (+-6.9)*	43.0 (+-5.9)	40.5 (+-4.1)
Opal+RelACP	277.0 (+-15.1)	278.5 (+-14.9)	45.2 (+-7.4)	41.4 (+-5.7)

Values with asterisk, in the same line, are statistically different (p<0.05).

Conclusions: OPF caused hardness decrease on enamel and dentin (p<0.05). NWA and the bioactive materials had a positive influence on the hardness of bleached enamel and dentin, except for the effect on enamel of the Biosilicate® material when applied for 5 min, 1x per week which showed a decrease in KHN.