Randomized clinical trial of the effect of NovaMin and CPP-ACPF in combination with dental bleaching

Abstract Objective This randomized, controlled, double-blind clinical study evaluated the effect of calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) on the prevention of post-operative sensitivity and on the effects of clinical bleaching treatment. Material and Methods Sixty volunteers were selected according to inclusion and exclusion criteria and were randomly assigned into three groups (n=20): CG (control group) patients, who were treated with 35% hydrogen peroxide; NOVAG (NovaMin group) patients, who were treated with 35% hydrogen peroxide followed by the application of NovaMin; and CPPG (CPP group) patients, who were treated with 35% hydrogen peroxide followed by the application of CPP-ACPF. Both bioactive agents were applied for five minutes. An evaporative stimulus associated with a modified visual scale was used to analyze sensitivity 24 hours after each bleaching session. The color evaluation was performed on the maxillary central incisors using a spectrophotometer. Associations between the intervention group, bleaching session, and reported sensitivity were tested using Chi-square partitioning. Results Color change values (ΔE) were analyzed using analysis of variance (ANOVA). The significance level used for both tests was 5%. In the intragroup assessment, the Friedman test showed that only the CPP-ACPF group showed no statistically significant difference (p<0.05) between baseline and first bleaching session. In the intergroup assessment, the Kruskal–Wallis test showed that the CPPG had less postoperative sensitivity after the first session, when compared to the other groups (p<0.05). Color change analysis (ΔE) showed a significant difference between the means obtained in the different bleaching sessions in all groups (p<0.05). Conclusions This study showed that the combination of CPP-ACPF with 35% hydrogen peroxide significantly reduced post-operative sensitivity in the first session, compared with the other evaluated treatments. The association of CPP-ACPF and NovaMin did not affect the color change induced by tooth bleaching.


Introduction
Tooth bleaching has become a popular approach because it is conservative and capable of changing tooth color 26 . The use of highly concentrated agents is preferred by many dentists in clinical practice because it affords the professional greater control, ensures greater patient safety, and requires fewer applications 24 .
Bleaching agents have an oxidizing action that leads to the formation of free radicals, reactive oxygen species, and hydrogen peroxide ions. These reactive molecules attack chromophores, causing their degradation and resulting in a bleaching effect 29 .
The most common adverse effect resulting from bleaching is dentinal sensitivity 5 , which is characterized by the manifestation of acute, short-term, or transient pain 16 . Moreover, it is currently believed that oxygen bubbles are formed in the dentinal tubules during the application of peroxides and that these bubbles can nerves, causing post-operative sensitivity 7 . This hypothesis therefore suggests that sensitivity after bleaching is a consequence of peroxide penetration into the internal tooth structure, causing the direct activation of neuronal receptors 18 .
Although saliva has a known remineralizing action 9 , it alone may not be able to increase the levels of available calcium and phosphate in the oral cavity and prevent the incidence of sensitivity 27 . To minimize or remineralizing solutions have been used to maintain a positive balance between demineralization and remineralization 3 . Bioactive agents containing calcium and phosphorus ions have thus been used to treat dentinal hypersensitivity 12 . In the presence of saliva occlude the dentinal tubules and reduce nerve-ending excitability without affecting the tooth bleaching process 25 .
Calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate have been used to promote enamel remineralization 17,20 , and they were therefore combined with bleaching treatments in this study.
An inorganic bioactive glass, known commercially as NovaMin, has also been used for treating dental hypersensitivity and for enamel remineralization.
This material was originally developed to act on bone regeneration because it has a ceramic structure containing amorphous calcium and sodium. NovaMin is therefore a highly water-reactive phosphosilicate obstruct the dentinal tubules 11 .
NovaMin is composed of sodium, phosphate, calcium, and silica, and it quickly releases calcium, phosphorus, and sodium ions when forming the hydroxyapatite layer 10 . NovaMin forms an amorphous layer rich in the ionic compound a 2 +3PO 4-, which is

Population and sample calculation
The software BioEstat ® (Civil Society Mamirauá, AM, Brazil) was used to calculate the sample size using data from a pilot study, which was conducted with ten volunteers and that followed the same procedures as 5%, and a sample loss prediction of 20% at the end of the study were considered for sample size calculation.
The sample calculated for this study was of 20 patients per group, totaling 60 patients.    Table 2).

Study design
The data analysis in Table 2      bleaching.
ppm) may have promoted not only remineralization, but also the formation of a more homogeneous enamel layer, which is less permeable to pigments derived from the diet. By contrast, the high solubility of the ionic layer formed by the NovaMin bioactive likely compromised the longevity of the bleaching treatment in this experimental group.
The results suggest that, under the examined conditions, tooth bleaching with CPP-ACPF causes less sensitivity in treated teeth than a bleaching agent alone or a bleaching agent plus NovaMin. None of the bioactive agents affected the tooth bleaching process.

Conclusion
The combination of CPP-ACPF with a bleaching treatment without a bioactive agent. The combination of NovaMin with bleaching treatment produced results similar to those obtained with bleaching treatment without a bioactive agent, and the association of either CPP-ACPF or NovaMin with 35% hydrogen peroxide did not affect the bleaching process.