Efeito da água ozonizada e gluconato de clorexidina sobre propriedades mecânicas e microbiológicas de materiais utilizados para confecção de próteses odontológicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Multi-step adhesive cementation versus one-step adhesive cementation: push-out bond strength between fiber post and root dentin before and after mechanical cycling

This study evaluated the effects of mechanical cycling on resin push-out bond strength to root dentin, using two strategies for fiber post cementation. Forty bovine roots were embedded in acrylic resin after root canal preparation using a custom drill of the fiber post system. The fiber posts were cemented into root canals using two different strategies (N = 20): a conventional adhesive approach using a three-step etch-and-rinse adhesive system combined with a conventional resin cement (ScotchBond Multi Purpose Plus + RelyX ARC ), or a simplified adhesive approach using a self-adhesive resin cement (RelyX U100). The core was built up with composite resin and half of the specimens from each cementation strategy were submitted to mechanical cycling (45 degree angle; 37 degrees C; 88 N; 4 Hz; 700,000 cycles). Each specimen was cross-sectioned and the disk specimens were pushed-out. The means from every group (n = 10) were statistically analyzed using a two-way ANOVA and a Tukey test (P = 0.05). The cementation strategy affected the push-out results (P < 0.001), while mechanical cycling did not (P = 0.3716). The simplified approach (a self-adhesive resin cement) had better bond performance despite the conditioning. The self-adhesive resin cement appears to be a good option for post cementation. Further trials are needed to confirm these results.

Contribuição ao estudo das relações dos conectores maiores de próteses parciais removíveis com tecidos gengivais

The effect in the gingival tissue of four distinctive types of relationships between the major conector and the gingival margin was investigated in eight subjects in association with the experimental gingivitis model. The subjects wore appliances constructed in acrylic resin (retained by means of embrasure hooks) throughout the day an night, except during meals. After the appliances had been placed, the subjects were abstained from any oral hygiene for twenty-one days. Records of the Plaque Index, Gingival Index and probing deplh were taken at baseline and at each week. Data showed that there was a small increase in the Plaque Index and Gingival Index for the four areas and that the degree of inflammation of the covered areas was higher in the area without relief

Registros posicionais de protrusão e lateralidade em resinaacrílica à partir de diferentes posições iniciais

The lateral movement presents a combination of lateral condylar and protrusive displacement on the non-working side. The objective os this study was to check the differences in the adjustment of the semiadjustable articulator starting from two different initial positions, centric relation an intercuspal position using positional records of rotusion and lateral movements in acrylic resin for the adjustment of condylar guidance as for ennett Angle. Twenty pacients dentate and assintomatic were recruited and their adjustment were performed in the semiadjustable articulator checking the differences among the studied groups, not finding statistically significant differences. Concludes that, in semiadjustable articulator adjustment, starting the montage in centric relation or intercuspal position, the results obtained for the condylar guidande and Bennett Angle aren´t statistically diferents, as well there is no difference in condylar guidance adjustment using lateral or protrusive records.

Considerações relevantes na seleção de dentes artificiais

Nowadays the search for aesthetic in removable dentures is considered a success clinical factor. Besides, both the selection of artificial denture teeth and the characterization of dentures have been based on the facial harmony and cultural factors. But these factors change over time. Therefore, the present study aimed to discuss the selection of artificial denture teeth in relation to patient’s variables such as face shape, skin color, hair color, eye color, age and gender. Moreover, artificial denture teeth’ color, shape and size were presented.

Influência do material oclusal na distribuição de tensões em próteses implantossuportadas unitárias

Objective: the aim of this study was to evaluate the influence of occlusal veneering material in single fixed implant-supported crowns through the 3-D finite element method. Material and methods: Four models were fabricated using the Rhinoceros 4.0, SolidWorks, and InVesalius softwares. Each model represented a block of mandibular bone with an external hexagon implant of 5 mm x 10 mm and different veneering materials including NiCr (1), porcelain (2), composite resin (3), and acrylic resin (4). An axial load of 200 N and an oblique load of 100 N were applied. Results: model (2) with porcelain veneering presented a lower stress concentration for the NiCr framework, followed by the composite resin and acrylic resin. The stress distribution to the implant and bone tissue was similar for all models. Conclusions: there is no difference of stress distribution to the implant and supporting structures by varying the veneering material of a single implant-supported prosthesis.

Influência do material oclusal na distribuição de tensões em próteses implantossuportadas unitárias

Objective: the aim of this study was to evaluate the influence of occlusal veneering material in single fixed implant-supported crowns through the 3-D finite element method. Material and methods: Four models were fabricated using the Rhinoceros 4.0, SolidWorks, and InVesalius softwares. Each model represented a block of mandibular bone with an external hexagon implant of 5 mm x 10 mm and different veneering materials including NiCr (1), porcelain (2), composite resin (3), and acrylic resin (4). An axial load of 200 N and an oblique load of 100 N were applied. Results: model (2) with porcelain veneering presented a lower stress concentration for the NiCr framework, followed by the composite resin and acrylic resin. The stress distribution to the implant and bone tissue was similar for all models. Conclusions: there is no difference of stress distribution to the implant and supporting structures by varying the veneering material of a single implant-supported prosthesis.

Fabrication techniques for ocular prostheses: an overview

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da resistência adesiva de diferentes sistemas resinosos de colagem ortodôntica

Recent orthodontic bonding materials have aimed to reduce the working time of the clinician, by simplifying the acid etching procedure by applying self-etching primer adhesive systems. However, the adhesion quality of these materials still demands investigation. Thus, the present study aimed to evaluate the bond strengths of three different adhesive systems. A hundred and eighty bovine lower incisors were cut and embebbed in acrylic resin matrices, in which orthodontic brackets were bonded with Transbond XT (2n = 60), Transbond XT Self Etching Primer (2n = 60) e Tyrian (2n = 60). For each composite, bond strength tests were executed immediately (n = 30) and 24 hours (n = 30) after the bonding, in the assay machine Versat 2000 (Pantec), by applying 500 Kgf of load at 1mm/min of velocity. Transbond XT, Transbond XT Self Etching Primer and Tyrian presented, respectively, average values of bond strength of 7.43, 7.09 and 3.41 MPa at the time immediately, and 7.42, 8.81 and 5.35 MPa at 24 hours after the bonding, where differences were statistically significant at 5% between Tyrian and Transbond groups at both observation times. It was concluded that Tyrian was the material that presented significant lower bond strength with regard to Transbond groups that were similar.

Biocompatibilidade de primers e adesivo utilizados na confecção de próteses maxilofaciais implantorretidas: análise in vitro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework

The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods: Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results: The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion: The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant.

Efeitos de lasers de alta potência na superfície de cerâmicas vítreas de dissilicato de lítio e sua resistência de união à dentina humana

Pós-graduação em Odontologia Restauradora - ICT

Efeitos de lasers de alta potência na superfície de cerâmicas vítreas de dissilicato de lítio e sua resistência de união à dentina humana

Pós-graduação em Odontologia Restauradora - ICT

Influence of artificial accelerated ageing on the colour stability of paints used for ocular prosthesis iris painting

Objectives: To evaluate the colour stability of paints used for ocular prosthesis iris painting submitted for accelerated artificial ageing (AAA). Materials and methods: Forty specimens of acrylic resin for sclera (16 x 2 mm) were made and separated into eight groups (n = 10) according to the type of paint (gouache, GP; oil, OP; acrylic AP; and composite resin for characterisation, CR) and the colours used (blue/brown). After drying (72 h), a new layer of colourless acrylic resin was applied and the initial colour readout was performed (Spectrophotometer PCB 6807). New colour readouts were performed after AAA, and Delta E was calculated. Results: Statistical analysis (two-way ANOVA-Bonferroni, p < 0.05) demonstrated that the brown colour showed lower Delta E means in comparison with the blue colour, with statistically significant difference for AP only. Blue colour showed no statistically significant difference with regard to the type of paint used. Brown AP showed lower Delta E than the other groups, with significant difference for OP and GP. GP showed greater alteration in Delta E for the brown colour, being statistically similar only to OP. Conclusions: Only the AP group for brown pigment shows clinically acceptable values for colour stability after AAA.

IMPROVEMENT TO THE MARGINAL COPING FIT OF COMMERCIALLY PURE TITANIUM CAST IN PHOSPHATE-BONDED INVESTMENT BY USING A SIMPLE PATTERN COATING TECHNIQUE

Statement of problem. Coatings of zirconite, Y2O3 or ZrO2 on wax patterns before investing in phosphate-bonded investments have been recommended to reduce the reaction layer in titanium castings, but they are not easily obtainable. Spinel-based investments are relatively stable with molten titanium and could be used as coatings to improve the quality of castings made with those investments. Purpose. The purpose of this study was to evaluate the effect of pattern coating with a commercial spinel-based investment before investing in 1 of 3 phosphate-bonded investments on the marginal coping fit and surface roughness of commercially pure titanium castings. Material and methods. Ten square acrylic resin patterns (12 x 12 x 2 mm) per group were invested in the phosphate-bonded investments Rematitan Plus (RP), Rema Exakt (RE), and Castorit Super C (CA) with or without a coating of the spinel-based investment, Rematitan Ultra (RU). After casting, the specimens were cleaned and the surface roughness was measured with a profilometer. Copings for dental implants with conical abutment were invested, eliminated, and cast as previously described. The copings were cleaned and misfit was measured with a profile projector (n=10). For both tests, the difference between the mean value of RU only and each value of the phosphate-bonded investment was calculated, and the data were analyzed by 2-way ANOVA and Tukey's HSD test (alpha=.05). In addition, the investment roughness was measured in bar specimens (30 x 10 x 10 mm), and the data (n=10) were analyzed by 1-way ANOVA and Tukey's HSD post hoc test (alpha=.05). Results. Two-way ANOVA for casting surface roughness was significant because of the investment, the coating technique, and the interaction between variables. One-way ANOVA was performed to prove the interaction term, and Tukey's post hoc test showed that RP with coating had the lowest mean, while RP had the highest. CA with coating was not different from RP with coating or CA without coating. RE with coating was similar to CA, while RE was different from all groups. For coping marginal fit, the 2-way ANOVA was significant for the investment, the coating technique, and the interaction between variables. The interaction was analyzed by1-way ANOVA and Tukey's HSD test that showed no significant difference among the coated groups, which had better marginal fit than the groups without coating. Among the groups without coating, CA had significant lower marginal misfit than RP, while RE was not different from CA and RP. For the investment surface roughness, the 1-way ANOVA was significant. CA and RU were smoother than RE and RP (P<.001). Conclusions. The coating technique improved the quality of castings fabricated with phosphate-bonded investments. (J Prosthet Dent 2012;108:51-57)