Princípios técnicos para o recontorno cosmético de dentes anteriores após finalizacão ortodôntica / Technical principies for the cosmetic contouring of anterior teeth after orthodontic treatment

A integração entre a ortodontia e a dentística restauradora são essenciais para alcançar uma perfeita harmonia funcional e estética do paciente. O caso clínico apresentado descreve um protocolo restaurador e os princípios técnicos para o recontorno cosmético com resinas compostas diretas em dentes anteriores. Um protocolo fotográfico, enceramento diagnóstico, uma técnica de estratificação com resinas compostas e procedimentos de acabamento e polimento foram utilizados para a reabilitação estética de uma paciente que apresentava diastemas generalizados após finalização do tratamento ortodôntico num caso de discrepância do tamanho dentário de Bolton. A abordagem multidisciplinar foi necessária para obter resultados estéticos satisfatórios e alcançar as expectativas da paciente

The integration between orthodontics and restorative dentistry is essential to achieve a perfect functional and aesthetic harmony for the patient. The clinical case presented hereby describes a restorative protocol and related technical principies for the cosmetic contouring of anterior maxillary teeth using direct resin composite restorations. A photographic protocol, a diagnostic wax-up, a resin composite stratification technique and finishing and polishing procedures were employed for the aesthetic rehabilitation of a patient presenting generalized homogeneous diastemas after orthodontic treatment due to Bolton tooth size discrepancy. A multidisciplinary approach was necessary to achieve successful aesthetic results and to satisfy the patient's expectations

The suitability of different FEA models for studying root fractures caused by wedge effect.

Finite element analysis (FEA) utilizing models with different levels of complexity are found in the literature to study the tendency to vertical root fracture caused by post intrusion ("wedge effect"). The objective of this investigation was to verify if some simplifications used in bi-dimensional FEA models are acceptable regarding the analysis of stresses caused by wedge effect. Three plane strain (PS) and two axisymmetric (Axi) models were studied. One PS model represented the apical third of the root entirely in dentin (PS-nG). The other models included gutta-percha in the apical third, and differed regarding dentin-post relationship: bonded (PS-B and Axi-B) or nonbonded (PS-nB and Axi-nB). Mesh discretization and material properties were similar for all cases. Maximum principal stress (sigma max) was analyzed as a response to a 165 N longitudinal load. Stress magnitude and orientation varied widely (PS-nG: 10.3 MPa; PS-B: 0.8 MPa; PS-nB: 10.4 MPa; Axi-B: 0.2 MPa; Axi-nB: 10.8 MPa). Axi-nB was the only model where all sigma max vectors at the apical third were perpendicular to the model plane. Therefore, it is adequate to demonstrate the tendency to vertical root fractures caused by wedge effect. Axi-B showed only part of the sigma max perpendicular to the model plane while PS models showed sigma max on the model plane. In these models, sigma max)orientation did not represent a situation where vertical root fracture would occur due to wedge effect. Adhesion between post and dentin significantly reduced sigma max.

Shear versus micro-shear bond strength test: a finite element stress analysis.

OBJECTIVES: This study aimed at comparing the stress distribution in shear and micro-shear test set-ups using finite element analysis, and suggesting some parameter standardization that might have important influence on the results. METHODS: Two-dimensional plane strain finite element analysis was performed using MSCPatran and MSCMarc softwares. Model configurations were based on published experimental shear and micro-shear test set-ups and material properties were assumed to be isotropic, homogeneous and linear-elastic. Typical values of elastic modulus and Poisson's ratios were assigned to composite, dentin and adhesive. Loading conditions considered a single-node concentrated load at different distances from the dentin-adhesive interface, and proportional geometry (1:5 scale, but fixed adhesive layer thickness in 50microm) with similar calculated nominal strength. The maximum tensile and shear stresses, and stress distribution along dentin-adhesive interfacial nodes were analyzed. RESULTS: Stress distribution was always non-uniform and greatly differed between shear and micro-shear models. A pronounced stress concentration was observed at the interfacial edges due to the geometric change: stress values farther exceeded the nominal strength and tensile stresses were much higher than shear stresses. For micro-shear test, the relatively thicker adhesive layer and use of low modulus composites may lead to relevant stress intensification. An appropriate loading distance was established for each test (1mm for shear and 0.1mm for micro-shear) in which stress concentration would be minimal, and should be standardized for experimental assays. SIGNIFICANCE: The elastic modulus of bonded composites, relative adhesive layer thickness and load application distance are important parameters to be standardized, once they influence stress concentration.

Restauração de cavidades de Classe II profundas: a busca da técnica ideal / Restoration of deep class II cavities: searching for the ideal technique

Este artigo traz ao clínico diferentes técnicas usadas para preencher cavidades classe II profundas com resinas compostas. Lista pontos essenciais para criar restaurações posteriores confiáveis, como a localização das margens gengivais em esmalte ou em dentina/cemento e o conhecimento e a habilidade do clínico em relação aos compósitos e às técnicas. Uma técnica restauradora alternativa é apresentada para ser utilizada em consultório com segurança.

Influence of adhesive system and placement technique on microleakage of resin-based composite restorations.

PURPOSE: To analyze the influence of two placement techniques and two adhesive systems on the marginal microleakage of Class II resin-based composite restorations using different resin composite materials. MATERIALS AND METHODS: Two hundred standardized Class II cavities (5 mm x 3 mm x 1.5 mm) were cut in human premolars and restored using five resin composite materials (A.L.E.R.T.-AL, Solitaire-SO, SureFil-SU, Filtek A110-A, and Z100-Z), two adhesive systems (Bond 1-B1 and Etch & Prime 3.0-EP), and two placement techniques (incremental or bulk). Specimens were thermocycled (700 cycles, 5 degrees - 55 degrees C, 1 min dwell time), immersed in 0.5% methylene blue solution for 4 h, and sectioned longitudinally to evaluate the extent of microleakage. Data were submitted to statistical analysis using the Kruskal-Wallis test. RESULTS: It was observed that both adhesive systems presented similar results (p > 0.05), and neither achieved complete marginal sealing. The bulk placement technique led to greater microleakage than the incremental technique (p < 0.001). Restorations prepared using SO resin composite showed greater microleakage than those performed using Z or AL materials. However, SO obtained similar values of microleakage when compared to SU and A materials. CONCLUSION: The use of incremental placement technique resulted in less microleakage for Class II resin-based composite restorations. No difference was observed among adhesive systems regarding prevention of marginal dye penetration. Furthermore, the type of resin composite material employed for restoration may have an influence on the extent of microleakage.

Influence of placement techniques on Vickers and Knoop hardness of class II composite resin restorations.

OBJECTIVES: To analyze the influence of two placement techniques on Knoop and Vickers hardness of class II cavities restored using packable (A.L.E.R.T., Solitaire 2, SureFil) and conventional microfilled and hybrid (Filtek A110 and Z250, respectively) resin composites. METHODS: Fifty standardized class II cavities (5 x 3 x 1.5 mm3) were prepared in human premolars. They were divided into ten groups (n = 5) and restored according to each resin composite material (A.L.E.R.T., Solitaire 2, SureFil, Filtek A110 and Z250) and placement technique (incremental or bulk). After storage in distilled water at 37 degrees C for 24 h, they were thermal cycled (700 cycles/5-55 degrees C, 1 min dwell time) and sectioned longitudinally. One section from each specimen was embedded and polished for Knoop and Vickers hardness measurements. Sixteen indentations were performed for each restoration, eight on the occlusal and eight on the cervical surfaces. RESULTS: Results were submitted to ANOVA and demonstrated that all materials presented lower hardness values at the cervical surfaces when the bulk placement technique was employed, when compared to the occlusal surfaces (p< 0.001) whereas the same did not occur with the incremental technique. Pearson's correlation test demonstrated a positive correlation between Vickers and Knoop hardness numbers. SIGNIFICANCE: The use of bulk placement technique resulted in lower values of hardness at the cervical surfaces of class II restorations. Values obtained using Knoop hardness test showed a high correlation with Vickers hardness measurements.

Influence of the substrate and load application method on the shear bond strength of two adhesive systems.

The difficulty with comparing data obtained from different research centers calls for the standardization of laboratory procedures. This in vitro study compared the shear bond strength (SBS) of two adhesive systems--a self-etching system, Etch&Prime 3.0 and a one-bottle total-etch system, Single Bond--using two methods of load application (orthodontic edge wire loop and knife-edge blade). The hypothesis of substrate influence on the results obtained for both tests was also investigated. Twenty-four recently extracted human teeth were embedded in PVC tubes using acrylic resin and divided into two groups (n=12). A proximal surface of each tooth was wet-ground flat to expose dentin. Etch&Prime 3.0 and Single Bond adhesive systems were applied according to the manufacturers' instructions, and cone-shaped restorations were then built using Z100 resin composite. After storage in distilled water at 37 degrees C for 24 hours, the specimens were submitted to SBS testing using an orthodontic edge wire loop. The same teeth were again embedded in PVC tubes using acrylic resin and the other proximal surface was wet-ground flat to expose dentin. The specimens were prepared as explained above, and after storage in distilled water under the same previous conditions, they were submitted to SBS testing using a knife-edge blade. Two-way ANOVA and Tukey's tests were performed to determine any statistically significant differences among testing conditions. Results indicated that SBS values obtained for Etch&Prime 3.0 were significantly lower than Single Bond for both methods of load application (p<0.001). Regarding the load application method, statistically significant higher values (p<0.01) were obtained for Etch&Prime 3.0 when the knife-edge blade was used, whereas, no significant difference was observed between the two methods for Single Bond. There was a significant correlation between the bond strength values obtained on the same tooth (p<0.05). SEM examination found that Etch&Prime 3.0 demonstrated narrower tags than Single Bond. Moreover, the peritubular dentin was not adequately decalcified when Etch&Prime 3.0 was used.

Microtensile dentin bond strength of self-etching and single-bottle adhesive systems in different cavity configurations.

PURPOSE: To evaluate the bond strength of a self-etching (Clearfil SE Bond) and a single-bottle (Excite) adhesive system using two cavity configurations (C-factors 5 and 1). MATERIALS AND METHODS: Class I cavities (3 x 4 x 2.5 mm) were prepared in 28 extracted human molars using diamond burs under water cooling. Teeth were divided into 4 groups: G1: Excite, C-factor 5; G2: Excite, C-factor 1; G3: Clearfil, C-factor 5; G4: Clearfil, C-factor 1. To determine C-factor 5, systems were applied to all cavity walls according to the manufacturers' instructions (5 bonded, 1 unbonded). For C-factor 1, lateral walls were isolated using nail varnish, and adhesive systems were only applied to the pulpal floor (5 unbonded, 1 bonded). Cavities were restored using Tetric Ceram composite resin (Ivoclar/Vivadent), and bulk light cured for 40 s (500 mW/cm2). Teeth were stored in distilled water for 24 h at 37 degrees C, and then sectioned using a diamond disk, yielding stick-shaped specimens with a bonded area of approximately 0.8 mm2. Specimens were submitted to the microtensile bond test at a rate of 1 mm/min speed in a universal testing machine. RESULTS: Resin-dentin bond strengths (MPa) were submitted to ANOVA and Tukey's tests (p < 0.05) [number of specimens]: G1 = 35.8b [43]; G2 = 48.9a [55]; G3 = 45.9a [60]; G4 = 49.0a [53]. There was no statistically significant difference between adhesive systems for C-factor 1. For C-factor 5, Clearfil SE Bond produced higher values when compared to the other group. CONCLUSION: Changes in C-factor only affected the total-etch adhesive system tested. This may be a result of the different filler volume in the self-etching system, and not of the bonding technique itself.

Microleakage of four simplified adhesive systems under thermal and mechanical stresses.

PURPOSE: To evaluate microleakage at the dentin margins of Class II resin-based composite restorations using four simplified adhesive systems: Etch & Prime 3.0, Prime & Bond NT, Clearfil Liner Bond 2V and Clearfil SE Bond, upon thermal and mechanical stresses. MATERIALS AND METHODS: Forty slot preparations (5mm x 3mm x 1.5mm) were cut in sound human molars with gingival margins below the cement/enamel junction. All adhesive systems were applied strictly according to manufacturers' instructions. Cavities were restored using Clearfil AP-X composite resin. After finishing and polishing, teeth were submitted to thermal (x700, 5-55 degrees C, 60-second dwell time) and consecutively mechanical cycling (100,000 cycle; 8 Kgf load). Specimens were coated with nail polish, immersed in silver nitrate for 2 hours and sectioned longitudinally with a diamond disc. The extent of leakage was ranked using a 0-4 scale. RESULTS: Statistical analysis was performed using Kruskal-Wallis test. Minimal leakage occurred with Clearfil SE Bond. There was a statistically significant difference (P<0.01) between this system and Clearfil Liner Bond 2V, although the latter also showed low values of dye penetration. No statistically significant difference was found between Etch & Prime 3.0 and Prime & Bond NT. Both showed statistically greater leakage than the two other systems (P<0.01).