Relação entre materiais dentários e o complexo dentino-pulpar

Despite the strong valorization of the esthetics and its relationship with restorative materials, the biological principles of any clinical procedure are extremely important to maintain the vitality of the dentin-pulp complex. Dentin and pulp tissue are susceptible to different kinds of irritants such as toxins from microorganisms, traumatic procedures of cavity preparation, as well as toxic components released by restorative materials applied in non recommended clinical situations. Initially, the pulp responds to irritation by starting an inflammatory reaction which involves outward movement of dentinal fluid and intratubular deposition of immunoglobulins, upregulation of odontoblast activities, presence of immune cells and their cytokines as well as local expression of neuropeptides and chemokines. After these initial events, the inflammation process can be resolved associated or not to sclerotic dentin formation and reactionary dentin deposition. If high intensity offensive stimuli are applied to the dentin-pulp complex, death of odontoblasts takes place and consequently pulp ageing or even partial necrosis of this tissue may occurs. Thereby, clinicians need to be aware about the physiological and pathological features of the dentin-pulp complex as well as the possible biological consequences of different clinical procedures. In this way, the dentists should be able to carry out minimally aggressive operative techniques and to select the more appropriate restorative materials for each specific clinical situation in order to obtain excellent clinical results associated to the maintenance of pulp vitality.

Fracture resistance of teeth submitted to several internal bleaching protocols

Aim: The aim of this study was to evaluate the fracture resistance of teeth submitted to several internal bleaching protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP), 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser or sodium perborate (SP). Materials and methods: After endodontic treatment, fifty bovine extracted teeth were divided into five groups (n = 10): G1-unbleached; G2-35HP; G3-37CP; G4-15HPTiO2 photoactivated by LED-laser and G5-SP. In the G2 and G4, the bleaching protocol was applied in 4 sessions, with 7 days intervals between each session. In the G3 and G5, the materials were kept in the pulp teeth for 21 days, but replaced every 7 days. After 21 days, the teeth were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until teeth fracture. The data were submitted to ANOVA and Tukey tests (α = 5%). Results: The 35HP, 37CP, 15HPTiO2 and SP showed similar fracture resistance teeth reduction (p > 0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p < 0.05). Conclusion: All bleaching protocols reduced the fracture resistance of endodontically-treated teeth, but there were no differences between each other. Clinical significance: There are several internal bleaching protocols using hydrogen peroxide in different concentrations and activation methods. This study evaluated its effects on fracture resistance in endodontically-treated teeth.

Human dental enamel and dentin structural effects after Er:yag laser irradiation

Ideally projected to be applied on soft tissues, infrared lasers were improved by restorative dentistry to be used in hard dental tissues cavity preparations-namely enamel and dentin. This paper evidentiates the relevant aspects of infrared Erbium laser's action mechanism and its effects, and characterizes the different effects deriving from the laser's beams emission. The criteria for use and selection of optimal parameters for the correct application of laser systems and infuence of supporting factors on the process, such as water amount and its presence in the ablation process, protection exerted by the plasma shielding and structural factors, which are indispensable in dental tissues cavity preparation related to restorative technique, are subordinated to optical modifcations caused by the interaction of the energy dissipated by these laser light emission systems in the targeted tissue substrate. Clinical relevance: Differences in the action of infrared Erbium laser system in regard to the nature of the ablation process and variations on the morphological aspects observed in the super-fcial structure of the target tissue irradiated, may be correlated to the structural optical modifcations of the substrate produced by an interaction of the energy propagated by laser systems.

Dental anxiety: prevalence and evaluation of psychometric properties of a scale

Aim: To estimate the reliability and validity of the Dental Anxiety Scale (DAS) and identify the prevalence and the effect of the socio-demographic characteristics of dental anxiety, in a sample of 212 adults. Methods: The psychometric sensitivity of the scale was assessed. A confirmatory factor analysis was performed, and the convergent validity and internal consistency were determined. The prevalence of anxiety was estimated, and the effect of socio-demographic variables on anxiety was assessed using structural equation modelling. Results: The participants’ mean age was 33.5 (SD = 15.6) years, and 62.3% were female. There was an adequate factorial adjustment of the scale in this sample. The convergent validity and internal consistency were adequate in the one-factor model. Regarding two-factor model, there was a high correlation (r) among the factors, which jeopardized the discriminant validity. A total of 47.6% of the participants (IC95% = 40.9 - 54.4) presented low levels of anxiety, 32.5% (IC95% = 26.2 - 38.9) moderate levels, and 12.3% (IC95% = 7.8 - 16.7) exacerbated levels. There was a non-significant effect of gender, age and education on the anxiety levels of this sample. Conclusion: We concluded that the one-factor model presented better psychometric qualities, that anxiety was highly prevalent and there was no significant effect of the demographic variables on anxiety, in this sample

Cytotoxic Effects of Zoledronic Acid on Human Epithelial Cells and Gingival Fibroblasts

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dental and skeletal components of Class II open bite treatment with a modified Thurow appliance

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

In Vitro Alkaline pH Resistance of Enterococcus faecalis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Three-dimensional dental arch changes of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of random/aligned nylon-6/MWCNT fibers on dental resin composite reinforcement

The aims of this study were (1) to synthesize and characterize random and aligned nanocomposite fibers of multi-walled carbon nanotubes (MWCNT)/nylon-6 and (2) to determine their reinforcing effects on the flexural strength of a dental resin composite.Nylon-6 was dissolved in hexafluoropropanol (10 wt%), followed by the addition of MWCNT (hereafter referred to as nanotubes) at two distinct concentrations (i.e., 0.5 or 1.5 wt%). Neat nylon-6 fibers (without nanotubes) were also prepared. The solutions were electrospun using parameters under low- (120 rpm) or high-speed (6000 rpm) mandrel rotation to collect random and aligned fibers, respectively. The processed fiber mats were characterized by scanning (SEM) and transmission (TEM) electron microscopies, as well as by uni-axial tensile testing. To determine the reinforcing effects on the flexural strength of a dental resin composite, bar-shaped (20 x 2 x 2 mm(3)) resin composite specimens were prepared by first placing one increment of the composite, followed by one strip of the mat, and one last increment of composite. Non-reinforced composite specimens were used as the control. The specimens were then evaluated using flexural strength testing. SEM was done on the fractured surfaces. The data were analyzed using ANOVA and the Tukey's test (alpha=5%).Nanotubes were successfully incorporated into the nylon-6 fibers. Aligned and random fibers were obtained using high- and low-speed electrospinning, respectively, where the former were significantly (p<0.001) stronger than the latter, regardless of the nanotubes'presence. Indeed, the dental resin composite tested was significantly reinforced when combined with nylon-6 fibrous mats composed of aligned fibers (with or without nanotubes) or random fibers incorporated with nanotubes at 0.5 wt%. (C) 2015 Elsevier Ltd. All rights reserved.

Multidisciplinary approach in the teaching of dental sculpture and anatomy

The purpose of the Dental Sculpture and Anatomy discipline is to introduce undergraduate students to the study of the anatomic and morphological characteristics of permanent and primary human dentition, through classes, books and cognitive and psychomotor activities. This discipline supports the teaching of specific knowledge necessary for a more extensive education, involving interdisciplinarity as a means of knowledge exchange among several areas of dentistry, to achieve comprehensive professional education. Students must recognize the dental morphology from samples of preserved teeth, and reproduce the morphology through three-dimensional models made of stone or wax blocks. In this article, the authors describe the process for producing teeth collars and macro dental models made of stone, their importance and benefits of utilization. The purpose of the study was to encourage the teaching of Dental Sculpture and Anatomy toundergraduate students of the Bauru School of Dentistry, University of Sao Paulo, through activities that would associate theory, practice and the development of manual skills.

Resistance to tetracycline and β-lactams and distribution of resistance markers in enteric microorganisms and pseudomonads isolated from the oral cavity

This study evaluated the occurrence of enteric bacteria and pseudomonads resistant to tetracycline and beta-lactams in the oral cavity of patients exhibiting gingivitis (n=89); periodontitis (n=79), periodontally healthy (n=50) and wearing complete dentures (n=41). Microbial identification and presence of resistance markers associated with the production of beta-lactamases and tetracycline resistance were performed by using biochemical tests and PCR. Susceptibility tests were carried out in 201 isolates of enteric cocci and rods. Resistance to ampicillin, amoxicillin/clavulanic acid, imipenem, meropenem and tetracycline was detected in 57.4%, 34.6%, 2.4%, 1.9% and 36.5% of the isolates, respectively. beta-lactamase production was observed in 41.2% of tested microorganisms, while the most commonly found beta-lactamase genetic determinant was gene bla(TEM). Tetracycline resistance was disseminated and a wide scope of tet genes were detected in all studied microbial genus.

Effects of dental bleaching on the color, translucency and fluorescence properties of enamel and dentin

The objective of this study was to evaluate the color, translucency and fluorescence of bovine enamel and dentin submitted to different bleaching modalities. Pairs of enamel and dentin discs (3 mm in diameter) were obtained from 150 bovine teeth. In 75 of the pairs, one specimen had the enamel removed (Dentin Group). The dentin was removed from one specimen of the remaining 75 pairs (Enamel Group) and the other specimen was left unaltered (Enamel + Dentin). The evaluation of color, translucency and fluorescence was performed with a spectrophotometer using the CIE L* a* b*. Each group was subdivided into three subgroups: Control, composed of specimens that were not bleached, and two experimental subgroups, bleached with either 10% carbamide peroxide (CP10%) or 35% hydrogen peroxide (HP35%). The CP10% bleaching gel was applied 2 h/day for 14 days. The HP35% bleaching agent was applied using two applications of 30 min each, with a one week interval between each application. When not being bleached, the specimens were immersed in artificial saliva. The color, translucency and fluorescence ratings were assessed using spectrophotometry 7 days after the treatment. Regarding color, significant differences were found between bleaching techniques in the groups Enamel and Enamel + Dentin, with a higher color difference for HP35%. Bleaching did not change the translucency of the dental tissues. There were significant differences for fluorescence for the HP35% subgroups of Dentin and Enamel + Dentin, and for the CP10% subgroup of Enamel. Dental bleaching changed the color and fluorescence of the dental tissues, however translucency was not affected.

Influence of dental chair backrest inclination on the registration of the mandibular position

Varying the inclination of the dental chair backrest might alter the distribution of occlusal contact points. The purpose of this study was to identify the influence of backrest inclination on the registration of the mandibular position. Ten participants aged between 18 and 30 years with a complete permanent dentition, uncompromised motor function, no tooth mobility, and no temporomandibular disorders were selected. To register interocclusal contacts, an autopolymerizing methylmethacrylate device was adapted to the maxillary anterior teeth and a composite resin increment was added to the mandibular central incisors. Contacts were registered with the following variations in the inclination of the dental chair backrest: 90 degrees, 120 degrees, and 180 degrees. A standardized digital photograph was made of each mark in each backrest position, and the images were superimposed to measure the distances in registration from 90 to 120 and from 90 to 180 degrees. Data were analyzed with the Student paired t test (α=.05). When the chair was inclined from the 90-degree to the 120-degree position, the mandible was repositioned posteriorly by a mean of 0.67 mm, but the difference was not statistically significant. When the chair was inclined from the 90-degree to the 180-degree position, however, the mandible was repositioned posteriorly by a statistically significant mean of 1.41 mm. Mandibular position is influenced by increasing inclination, and this influence was statistically significant at a 180-degree incline.

Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)