Effect of time in hardness test on artificially demineralized human dental enamel

A cross-sectional microhardness (CSMH) test was carried out in human dental enamel exposed to a demineralizing solution in order to evaluate two different times of indentation in sound tissue and artificially induced caries. Twenty caries-free extracted human molars had one of their smooth surfaces sectioned and the enamel surface was isolated with nail polish except for an area of 6 mm2. These specimens were submitted to artificially induced enamel caries on a lactate buffer containing 0.1 ppm fluoride (F) during 28 days. All specimens were bisected to create groups A and B in which CSMH test was performed employing a Knoop indenter with a 25g load for 5 or 10 s, respectively. Student's paired t-test (p<0.05) was used to determine statistically significant differences between group A and B in 7 depths. There were no significant differences between any of the analyzed depths. Since the present experiment showed no significant difference when comparing indentations made with a 25 g load during either 5 or 10 s in different depths, this method can be used with either one of the time intervals tested without compromising a CSMH test on artificially demineralized human enamel.

Influence of the construction bite vertical and horizontal dimensions on dentoskeletal structures induced by the Klammt appliance in Class II treatment

Aim: To evaluate the influence of construction bite in the dentoskeletal changes induced by Klammt Appliance. Methods: The sample consisted of 17 children, with Class II malocclusion and initial mean age of 8.5 years. The construction bite was obtained using an Exactobite on edge-toedge anteroposterior relationship with 3 mm interincisal clearance. The height of the acrylic was determined by initial overbite associated to interincisal clearance and measured with digital caliper. The amount of advancement was obtained and measured by initial overjet in the lateral radiography. Pearson's correlation, linear regression and ANOVA were used to determine the relationship between dentoskeletal and construction bite variables. Results: The increase in the height of the acrylic promotes a greater inhibition of the forward displacement of the nasal spine and reduction in the facial growth index. The increase in the mandibular advancement induces more downward displacement of nasal spine and pogonion; a counter-clockwise rotation of palatine plane; an increase in mandibular length, maxillary alveolar height and interincisal angle; a decrease in mandibular alveolar height, the intermaxillary discrepancy and overjet; and palatal tipping of upper incisors. Conclusions: The different dimensions of the construction bite influence the dentoskeletal changes induced by the appliance in Class II treatment.

Use of grape polyphenols against carcinogenesis: Putative molecular mechanisms of action using in vitro and in vivo test systems

Polyphenols are present in foods and beverages and are related to sensorial qualities such as color, bitterness, and astringency, which are relevant in wine, tea, grape juice, and other products. These compounds occur naturally in forms varying from simple phenolic acids to complex polymerized tannins. Thus, it is reasonable to expect that grape-derived products elaborated in the presence of skins and seeds, such as wine and grape juice, are natural sources of flavonoids in the diet. Carcinogenesis is a multistep process that is characterized by genetic, epigenetic, and phenotypic changes. With increasing knowledge of these mechanisms, and the conclusion that most cases of cancer are preventable, efforts have focused on identifying the agents with potential anticancer properties. The use of grape polyphenols against the carcinogenesis process seems to be a suitable alternative for either prevention and/or therapeutic purposes. The aim of this article is to show the molecular data generated from the use of grape polyphenols against carcinogenesis using in vivo and in vitro test systems. © Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition.

Long-term skeletal and dental effects and treatment timing for functional appliances in Class II malocclusion

Objective: To analyze the long-term skeletal and dentoalveolar effects and to evaluate treatment timing of Class II treatment with functional appliances followed by fixed appliances.Materials and Methods: A group of 40 patients (22 females and 18 males) with Class II malocclusion consecutively treated either with a Bionator or an Activator followed by fixed appliances was compared with a control group of 20 subjects (9 females and 11 males) with untreated Class II malocclusion. Lateral cephalograms were available at the start of treatment (mean age 10 years), end of treatment with functional appliances (mean age 12 years), and long-term observation (mean age 18.6 years). The treated sample also was divided into two groups according to skeletal maturity. The early-treatment group was composed of 20 subjects (12 females and 8 males) treated before puberty, while the late-treatment group included 20 subjects (10 females and 10 males) treated at puberty. Statistical comparisons were performed with analysis of variance followed by Tukey's post hoc tests.Results: Significant long-term mandibular changes (Co-Gn) in the treated group (3.6 mm over the controls) were associated with improvements in the skeletal sagittal intermaxillary relationship, overjet, and molar relationship (similar to 3.0-3.5 mm). Treatment during the pubertal peak was able to produce significantly greater increases in total mandibular length (4.3 mm) and mandibular ramus height (3.1 mm) associated with a significant advancement of the bony chin (3.9 mm) when compared with treatment before puberty.Conclusion: Treatment of Class II malocclusion with functional appliances appears to be more effective at puberty. (Angle Orthod. 2013;83:334-340.)

Impact of Quantity of Resin, C-factor, and Geometry on Resin Composite Polymerization Shrinkage Stress in Class V Restorations

Objective: This study evaluated the effect of quantity of resin composite, C-factor, and geometry in Class V restorations on shrinkage stress after bulk fill insertion of resin using two-dimensional finite element analysis.Methods: An image of a buccolingual longitudinal plane in the middle of an upper first premolar and supporting tissues was used for modeling 10 groups: cylindrical cavity, erosion, and abfraction lesions with the same C-factor (1.57), a second cylindrical cavity and abfraction lesion with the same quantity of resin (QR) as the erosion lesion, and then all repeated with a bevel on the occlusal cavosurface angle. The 10 groups were imported into Ansys 13.0 for two-dimensional finite element analysis. The mesh was built with 30,000 triangle and square elements of 0.1 mm in length for all the models. All materials were considered isotropic, homogeneous, elastic, and linear, and the resin composite shrinkage was simulated by thermal analogy. The maximum principal (MPS) and von Mises stresses (VMS) were analyzed for comparing the behavior of the groups.Results: Different values of angles for the cavosurface margin in enamel and dentin were obtained for all groups and the higher the angle, the lower the stress concentration. When the groups with the same C-factor and QR were compared, the erosion shape cavity showed the highest MPS and VMS values, and abfraction shape, the lowest. A cavosurface bevel decreased the stress values on the occlusal margin. The geometry factor overcame the effects of C-factor and QR in some situations.Conclusion: Within the limitations of the current methodology, it is possible to conclude that the combination of all variables studied influences the stress, but the geometry is the most important factor to be considered by the operator.

Presence of Cytoplasmic Organelle chromatoid body in class Insecta

In the present work we made a review on the cytoplasmic organelle chromatoid body (CB) in the Insecta class. We note that the CB has been described in 14 orders of insects. However, we emphasize the importance of new orders should be analyzed, since the detailed knowledge of the reproductive biology of insects may help in understanding taxonomic, evolutionary and mainly contribute to the development of tools that minimize the populations of vectors and insect pests, contributing directly to human welfare.

Cone-beam evaluation of pharyngeal airway space in class I, II, and III patients

The purpose of this study is to make a 3-dimensional (3-D) evaluation of the pharyngeal airway space (PAS) in patients with class I, II, and III malocclusion. Sixty patients were evaluated. The patients were divided in 3 groups according to their occlusion classification. The volume and area of PAS were evaluated using the software Dolphin 3-D Imaging in the preoperative period for orthognathic surgery. PAS volume and area were influenced by different patterns of malocclusion. The mean volume and area for class III patients were statistically bigger than for classes I and II patients (P < .001). There was also a significant difference for volume values between class I and II patients, being the bigger volume for the class I patients (P < .05). It was possible to conclude that the class III patients presented a bigger PAS compared with classes I and II patients.

Masticatory efficiency in class II and class III dentofacial deformities

Masticatory efficiency may be impaired in individuals with dentofacial deformities. The objective of the present study was to determine the condition of masticatory efficiency in individuals with dentofacial deformities. 30 patients with class II (DG-II) and 35 patients with class III (DG-III) dentofacial deformity participated in the study, all had an indication for orthognathic surgery. 30 volunteers (CG) with no alterations of facial morphology or dental occlusion and with no signs or symptoms of temporomandibular joint dysfunction also participated. Masticatory efficiency was analysed using a bead system (colorimetric method). Each individual chewed 4 beads, one at a time, over 20 s measured with a chronometer. The groups were compared in term's of masticatory efficiency using analysis of variance (ANOVA), with the level of significance set at P < 0.05. Masticatory efficiency was significantly greater in CG (P < 0.05) than in DG-II and DG-III in all chewing tasks tested, with no significant difference between DG-II and DG-III (P > 0.05). It was observed that the presence of class II and class III dentofacial deformity affected masticatory efficiency compared to CG, although there was no difference between DG-II and DG-III.

Prospective study of dentoskeletal changes in class II division malocclusion treatment with twin force bite corrector

Objective: To evaluate the dentoskeletal changes of Class II malocclusion treatment with the Twin Force Bite Corrector (TFBC). Materials and Methods: The sample comprised 86 lateral cephalograms obtained from 43 subjects with Class II division 1 malocclusion; the subjects were divided into two groups. The experimental group comprised 23 patients with a mean initial age of 12.11 years who were treated with the TFBC for a mean period of 2.19 years. The control group included 40 lateral cephalograms from 20 Class II nontreated patients, with an initial mean age of 12.55 years and a mean observation period of 2.19 years. The lateral cephalograms were evaluated before and after orthodontic treatment in group 1 and in the beginning and end of the observation period in group 2. t-Tests were used to compare the initial and final cephalometric characteristics of the groups as well as the amount of change. Results: The experimental group presented greater maxillary growth restriction and mandibular retrusion than the control group, as well as greater maxillomandibular relationship improvement and greater labial tipping of the mandibular incisors. The results also showed a greater decrease in overbite and overjet in the experimental group, and there were no statistically significant differences in the craniofacial growth pattern between groups. Conclusions: The TFBC promotes restriction of anterior maxillary displacement without significant changes in mandibular length and position and improvement of maxillomandibular relationship without changes in facial growth and significant buccal tipping of mandibular incisors. Class II correction with the TFBC occurred primarily as a result of dentoalveolar changes.

Extraction of maxillary first molars improves second and third molar inclinations in Class II Division 1 malocclusion

The aim of this study was to assess the changes in inclination of the maxillary second (M2) and third (M3) molars after orthodontic treatment of Class II Division 1 malocclusion with extraction of maxillary first molars.

How minimal grade goals and self-control capacity interact in predicting test grades

The present research examined the prediction of school students' grades in an upcoming math test via their minimal grade goals (i.e., the minimum grade in an upcoming test one would be satisfied with). Due to its significance for initiating and maintaining goal-directed behavior, self-control capacity was expected to moderate the relation between students' minimal grade goals and their actual grades. Self-control capacity was defined as the dispositional capacity to override or alter one's dominant response tendencies. Prior to a scheduled math test, 172 vocational track students indicated their minimal grade goal for the test and completed a measure of self-control capacity. The test grade was assessed at a second time of measurement. As expected, minimal grade goals more strongly predicted the actual test grades the higher the students' self-control capacity. Implications can be seen in terms of optimizing the prediction and advancement of academic performance.