Rogério Lacerda-Santos

In vivo biocompatibility versus degree of conversion of resin-reinforced cements in different time periods

This study focused on test the null hypothesis that there is no difference between the degree of conversion and biocompatibility of different resin reinforced glass ionomer cements (RRGICs). Forty‐eight male Wistar rats were used, distributed into four groups (n = 12), as follows: Group C (Control, polyethylene), Group FOB (Fuji Ortho Band), Group UBL (Ultra band Lok), and Group MCG (Multicure Glass), in subcutaneous tissue. The events of edema, necrosis, granulation tissue, multinuclear giant cells, young fibroblasts, and collagen formation were analyzed at 7, 15, and 30 days. The degree of conversion was evaluated by the Fourier method. Biocompatibility and degree of conversion were assessed using the Kruskal–Wallis and Dunn tests, and ANOVA and Tukeys test, respectively (P < 0.05). It was observed that, there was significant difference between Groups FOB and UBL for the presence of young fibroblasts at 15 days (P = 0.034) and between the Control and MCG Groups for the presence of multinucleated giant cells at 30 days (P = 0.009). Monomer conversion increased progressively until day 30, with significant difference between Group FOB and Groups UBL and MCG (P = 0.013) at 15 days. The null hypothesis was partially accepted, Fuji Ortho Band showed a less monomer conversion and a smaller number of young fibroblasts in the time of 15 days. Microsc. Res. Tech. 77:335–340, 2014.

Effect of degree of conversion on in vivo biocompatibility of flowable resin used for bioprotection of mini-implants.

OBJECTIVE To test the hypothesis that there is no difference between the biocompatibility and degree of monomer conversion of flowable resins used as bioprotective materials of orthodontic mini-implants. MATERIALS AND METHODS Forty-eight male Wistar rats were divided into four groups (n  =  12). Group Control (polyethylene), Group Wave, Group Top Comfort, and Group Filtek. The animals were sacrificed after time intervals of 7, 15, and 30 days and tissues were analyzed under optical microscopy for inflammatory infiltrate, edema, necrosis, granulation tissue, multinucleated giant cells, and collagen formation. The degree of conversion was evaluated by the Fourier method. Biocompatibility and degree of conversion were evaluated by the Kruskal-Wallis and Dunn tests, and analysis of variance and the Tukey test, respectively (P < .05). RESULTS An intense inflammatory infiltrate was observed on the seventh day, with Groups Top Comfort and Filtek differing statistically from Group Control (P  =  .016). Edema, necrosis, granulation tissue, and giant cells showed greater expressiveness at 7 days, without statistical difference between them (P > .05). For the presence of collagen fibers, Group Top Comfort was shown to differ statistically from Group Control (P  =  .037) at 15 days and from Groups Filtek and Control (P  =  .008) at 30 days. Monomer conversion ranged from 62.3% in Group Top Comfort at 7 days to 79.1% in Group Filtek at 30 days. CONCLUSIONS The hypothesis was rejected. The resin Top Comfort demonstrated lower tissue repair capacity with a lower number of collagen fibers compared with Filtek and Wave resins. The resin Top Comfort showed the lowest conversion values during the experiment.

Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion

The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM). Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10). The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva). Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukeys test and Students t test (α = 0.05). After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish.

Esthetic perception of facial profile after treatment with the Thurow appliance

The objective of this article was to investigate the perception of esthetic changes in the facial profile of bilateral Class II patients treated with the Modified Thurow Appliance for extraoral treatment. Silhouettes were traced of profiles of patients who initially presented a bilateral Class II molar relationship and who, post-treatment, presented molars in a Class I relationship. Three groups were formed: the first composed of patients with maxillary protrusion (SNA >84°), the second with maxillary retrusion (SNA <80°), and the third with a well-positioned maxilla (SNA 80-84°). A panel of 200 lay evaluators judged the profile esthetics by a randomized drawing of the silhouettes. The multiple analysis results showed that the profile esthetic scores for the three positions of the maxilla were greatly influenced by significant interactions with the characteristics (like sex and age) of the evaluators: retrusive maxilla (Score *Age Group, p < 0.001), normal maxilla (Score *Sex, p = 0.024; Score *Age Group, p = 0.050) and protrusive maxilla (Score *Age Group, p < 0.001). It was observed that the profile of Class II patients with protrusion, normal relationship and retrusion of the maxilla, improved in their esthetic post-treatment result; however, the evaluators showed greater satisfaction with the groups of protrusion and normal position of the maxilla. The Modified Thurow Appliance provided significant improvements in the esthetics of the profile of patients who presented protrusion and normal position of the maxilla. However, its use was not the best treatment option for patients with maxillary retrusion.

Optimizing Esthetics and Function in a Case of Moderate Reduced Bone Support.

The aim of this article is to report the orthodontic treatment of a woman aged 53 years 6 months whose chief complaint involved her facial esthetics and crowding. She presented a moderate reduction in bone support, but no periodontal disease, over the past 15 years. The maxillary left first premolar and both mandibular first premolars were extracted. The dental protrusion was reduced and all the spaces were closed, resulting in a significant improvement in facial esthetics. After 16 months, the satisfactory results in terms of the functional position of the teeth were maintained with the bone level remaining unchanged.