Efetividade do clareamento dentário com peróxido de carbamida a 10% e avaliação dos efeitos adversos sobre o esmalte dentário

The aim of the present study was to assess the effectiveness and adverse effects on dental enamel caused by nightguard vital bleaching with 10% carbamide peroxide. This was accomplished through the interaction of researchers from different areas such as dentistry, materials engineering and physics. Fifty volunteers took part in the doubleblind randomized controlled clinical trial. They were allocated to an experimental group that used Opalescence PF 10% (OPA) and a control group that used a placebo gel (PLA). Fragments of human dental enamel from the vestibular surface of healthy premolars, extracted for orthodontic reasons, were fixed to the vestibular surface of the first upper molars of the volunteers for in situ observation. Bleaching was performed at night for 21 days. The observation periods included Baseline (BL), T0 (21 days), T30 (30 days after treatment) and T180 (180 days after treatment, only for the OPA group). Tooth color was assessed by comparing it with the Vita® scale and by the degree of satisfaction expressed by the volunteer. We also assessed adverse clinical effects, dental sensitivity and gingival bleeding. The study of adverse effects on enamel was conducted in vivo and in situ, using the DIAGNOdent® laser fluorescence device to detect mineral loss. Scanning electron microscopy (SEM) was used to check for superficial morphological alterations, energy dispersive spectrophotometry (EDS) to semiquantitatively assess chemical composition using the Ca/P ratio, and the x-ray diffraction (XRD) technique to observe alterations in enamel microstructure. The results showed that nightguard vital bleaching with 10% carbamide peroxide was effective in 96% of the cases, versus 8% for the PLA group. Dental sensitivity was present in 36% (9/25) of the cases. There was no significant association between gingival bleeding and the type of gel used (p = 1.00). In vivo laser fluorescence analysis showed no difference in values for the control group, whereas in the OPA group there was a statistically significant difference between baseline values in relation to the subsequent periods (p<0.01), with lower mean values for post-bleaching times. There was a significant difference between the groups for times T0 and T30. Micrographic analysis showed no enamel surface alterations related to the treatment performed. No significant alteration in Ca/P ratio was observed in the OPA group (p = 0.624) or in the PLA group (p = 0.462) for each of the observation periods, nor between the groups studied (p=0.102). The XRD pattern for both groups showed the presence of three-phase Hydroxyapatite according to JCPDS files (9-0432[Ca5(PO4)3(OH)], 18-0303[Ca3(PO4)2.xH2O] and 25-0166[Ca5(PO4)3(OH, Cl, F)]). No other peak associated to other phases was found, independent of the group analyzed, which reveals there was no disappearance, nucleation or phase transformation. Neither was there any alteration in peak pattern location. With the methodology and protocol used in this study, nightguard vital bleaching with 10% carbamide peroxide proved to be an effective and safe procedure for dental enamel

Immunohistochemical expression of E-cadherin and beta-catenin in ameloblastomas and tooth germs

OBJECTIVE: The aim was to analyze the expression of E-cadherin and beta-catenin in ameloblastomas and tooth germs to determine their roles in cell differentiation processes and invasiveness compared with odontogenesis. STUDY DESIGN: Twenty-one ameloblastoma cases (16 solid and 5 unicystic tumors) and 5 tooth germs were submitted to the immunohistochemical detection of E-cadherin and beta-catenin. Immunoreactivity was evaluated using descriptive and semiquantitative analysis, investigating the location and intensity of staining. The Fisher exact test was performed, and P values of <.05 were considered to indicate statistical significance. RESULTS: There was no statistically significant difference in the expression of E-cadherin and beta-catenin between solid and unicystic ameloblastomas (P = .59; P = .63; respectively). The same was found when comparing solid and unicystic ameloblastomas with the tooth germs for both E-cadherin (P = .53; P = .44; respectively) and beta-catenin (P = .12; P = .16; respectively). Nuclear staining of beta-catenin was observed in only 4 cases (3 solid and 1 unicystic tumor). CONCLUSION: The results showed no differences in the expression of E-cadherin or beta-catenin between tooth germs and solid and unicystic ameloblastomas. The expression of these molecules seems mainly to be related to the process of cell differentiation.

Immunoexpression of integrins in ameloblastoma, adenomatoid odontogenic tumor, and human tooth germs

The expression of integrins alpha2beta1, alpha3beta1, and alpha5beta1 in 30 ameloblastomas (20 solid and 10 unicystic tumors), 12 adenomatoid odontogenic tumors (AOTs), and 5 human tooth germs in different stages of odontogenesis was analyzed. The distribution, location, pattern, and intensity of immunohistochemical expression were evaluated. Intensity was analyzed using scores (0 = absence, 1 = weak staining, and 2 = strong staining). No difference in the immunoexpression of the integrins was observed between solid and unicystic ameloblastomas. When these two ameloblastoma types were pooled into a single group, the following significant differences were found: immunoexpression of integrin alpha2beta1 was stronger in ameloblastomas than in AOTs and tooth germs, and the expression of integrin alpha5beta1 was stronger in ameloblastomas than in AOTs. The lack of detection of integrin alpha3beta1 in tooth germs and its detection in the odontogenic tumors studied suggest that this integrin might be used as a marker of neoplastic transformation in odontogenic tissues.

Immunoexpression of integrins in ameloblastoma, adenomatoid odontogenic tumor, and human tooth germs

The expression of integrins alpha2beta1, alpha3beta1, and alpha5beta1 in 30 ameloblastomas (20 solid and 10 unicystic tumors), 12 adenomatoid odontogenic tumors (AOTs), and 5 human tooth germs in different stages of odontogenesis was analyzed. The distribution, location, pattern, and intensity of immunohistochemical expression were evaluated. Intensity was analyzed using scores (0 = absence, 1 = weak staining, and 2 = strong staining). No difference in the immunoexpression of the integrins was observed between solid and unicystic ameloblastomas. When these two ameloblastoma types were pooled into a single group, the following significant differences were found: immunoexpression of integrin alpha2beta1 was stronger in ameloblastomas than in AOTs and tooth germs, and the expression of integrin alpha5beta1 was stronger in ameloblastomas than in AOTs. The lack of detection of integrin alpha3beta1 in tooth germs and its detection in the odontogenic tumors studied suggest that this integrin might be used as a marker of neoplastic transformation in odontogenic tissues.