Comparação da desadaptação marginal de infra-estruturas metálicas obtidas com variações na técnica de fundição, revestimentos e material para obtenção dos padrões

Pós-graduação em Odontologia - FOA

Avaliação da adaptação marginal de restaurações cerâmicas inlay após a cimentação

Pós-graduação em Odontologia Restauradora - ICT

Adaptação marginal e resistência à fratura de coroas totais executadas em diferentes sistemas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da concentração do líquido especial e da temperatura do molde de revestimentos na desadaptação marginal de coroas fundidas em titânio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The effect of an Er,Cr:YSGG laser on external adaptation of healthy and decayed cavities

The aim of this study was to evaluate the influence of chlorhexidine and Er, Cr:YSGG laser irradiation on the bond strength and external adaptation in mixed healthy and caries-affected class V cavities before and after thermal cycling. Thirty-six cavity preparations were made in mixed class V buccal human molars, half of them being artificially caries-induced. Any remaining affected dentin was removed from the cavity with a round burr at low speed. The teeth were divided into six groups, according to cleaning agent for both healthy and caries-induced dentin: no treatment, chlorhexidine and erbium, chromium-doped: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser irradiation. A Filtek P90 (3M ESPE, St Paul, MN, USA) silorane adhesive restorative system was used. The specimens were subjected to 5000 thermal cycles (5-55 degrees C 60 min). Epoxy replicas were obtained to characterize the external adaptation under scanning electron microscopy. The average percentages of non-continuous margins were 5.41% and 6.49% in enamel dentin before thermal cycling and 25% and 33.7% after thermal cycling, respectively. The caries-affected and laser irradiated cavities showed higher non-continuous margins. Thermal cycling was able to raise the percentage of non-continuous margin for all groups. Chlorhexidine did not affect the marginal adaptation results, and the Er,Cr:YSGG laser irradiation showed significantly worse results compared with the control group.

Influência do ciclo de sinterização da porcelana na adaptação marginal de infraestruturas de NiCrTi em função da biomecânica do preparo

A metal coping may undergo changes during porcelain firing, which compromises its marginal adaptation. The use of NiCrTi alloy proposes to minimize this effect through the high melting point of titanium present in its composition. This study evaluated the influence of porcelain firing cycle on the marginal adaptation of NiCrTi copings in different preparation designs. Forty standardized metal dies were fabricated with the following combinations finish line/convergence of the axial walls: 1) shoulder/6°; 2) shoulder/20°; 3) sloping shoulder/6°; 4) sloping shoulder/20°. On each die a metal ceramic restoration coping was made. The die/coping set was stabilized with orthodontic elastics, divided into four equidistant areas with three measurement points each and a cementation pressure was simulated. The measurements were taken under a stereomicroscope (32×). After the first measurement, the copings were submitted to sintering cycles simulating porcelain application. For repeated measurements, the same procedures described above were performed. Data were submitted to Student’s-t test, 1-way ANOVA and Tukey´s test (α = 0.05). Adaptation means (µm) before and after porcelain firing in different preparations were: 1) 111.92 and 127.31; 2) 124.15 and 135.48; 3) 122.19 and 138.77; 4) 166.09 and 186.72; respectively. The porcelain firing impaired adaptation, regardless of the preparation design. The preparation in a 20° sloping shoulder provided a worse adaptation when compared with preparations that had 6° and 20° shoulder, which were statistically equal. The 6° sloping shoulder was statistically equal to the other three preparation designs.

Evaluation of dental restorations: a comparative study between clinical and digital photographic assessments

The aim of this study was to compare the efficacy of a direct clinical evaluation method with an indirect digital photographic method in assessing the quality of dental restorations. Seven parameters (color, occlusal marginal adaptation, anatomy form, roughness, occlusal marginal stain, luster, and secondary caries) were assessed in 89 Class I and Class II restorations from 36 adults using the modified US Public Health Service/Ryge criteria. Standardized photographs of the same restorations were digitally processed by Adobe Photoshop software, separated into the following four groups and assessed by two calibrated examiners: Group A: The original photograph displayed at 100%, without modifications (IMG100); Group B: Formed by images enlarged at 150% (IMG150); Group C: Formed by digital photographs displayed at 100% (mIMG100), with digital modifications (levels adjustment, shadow and highlight correction, color balance, unsharp Mask); and Group D: Formed by enlarged photographs displayed at 150% with modifications (mIMG150), with the same adjustments made to Group C. Photographs were assessed on a calibrated screen (Macbook) by two calibrated clinicians, and the results were statistically analyzed using Wilcoxon tests (SSPS 11.5) at 95% CI. Results: The photographic method produced higher reliability levels than the direct clinical method in all parameters. The evaluation of digital images is more consistent with clinical assessment when restorations present some moderate defect (Bravo) and less consistent when restorations are clinically classified as either satisfactory (Alpha) or in cases of severe defects (Charlie). Conclusion: The digital photographic method is a useful tool for assessing the quality of dental restorations, providing information that goes unnoticed with the visual-tactile clinical examination method. Additionally, when analyzing restorations using the Ryge modified criteria, the digital photographic method reveals a significant increase of defects compared to those clinically observed with the naked eye. Photography by itself, without the need for enlargement or correction, provides more information than clinical examination and can lead to unnecessary overtreatment.

Influência de técnicas de moldagem e de dois vazamentos na precisão dimensional de modelos de gesso e adaptação marginal de infraestruturas CAD/CAM em Y-TZP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação do selamento de ápices radiculares retrobturados ou recobertos com diferentes materiais mediante infiltração marginal por corante e análise da interface em microscopia eletrônica de varredura

The purpose of this study was to evaluate the apical sealing ability and the marginal adaptation of five dental materials used in retrofillings or applied to the bevelled root surface. One hundred and forty extracted single rooted human teeth were used, divided into seven groups of twenty each. ln the first, second, third and fourth groups, the teeth were apicoectomized, submitted to cavity preparations and retrofilled with one of the following materiais: zinc free silver amalgam, a dentin bonding system plus composite resin, a glass ionomer cement ora compomer. In the fifth, sixth and seventh groups, the teeth were apicoectomized and capped on the bevelled root surface with one of the following materiais: a dentin bonding system plus composite resin, a glass ionomer cement or a compomer. Two specimens of each experimental group were evaluated for the marginal adaptation using scanning electron microscopy. The remaining 126 specimens were immersed in 2% methylene blue dye, stored for one week at 37ºC and the infiltration was evaluated with a stereomicroscope. The results showed that the glass ionomer cement presented the lowest values of marginal infiltration when used as retrofilling material, with a significant statistical difference when compared with the others tested materials. When used as apical capping, the glass ionomer cement and the compomer were equivalent and significantly better than the dentin bonding system plus composite resin. Using scanning electron microscopy, all the materials showed some slight adjustment problem. ln the retrofilling, the smallest marginal gaps were observed with the compomer and the dentin bonding system plus composite resin, while the largest were observed with the glass ionomer cement and zinc free silver amalgam. ln the apical capping, the smallest marginal gaps were observed with the compomer and the dentin bonding system plus composite resin and ...

Kinetic parameters and monomeric conversion of different dental composites using standard and soft-start photoactivation modes

This paper evaluates the photopolymerization kinetics and degree of conversion of different commercial dental composites when photoactivated by a LED curing unit using two different modes (standard and soft-start mode). The investigation was performed on with RelyX ARC (dual-cured), Filtek Z-350 (Nanocomposite), Filtek Z-250 (Hybrid), and Filtek Z-350flow (Flowable) resin composites. The analysis used was attenuated total reflection with a Fourier transform infrared (ATR-FTIR). The RelyX ARC resin demonstrated the highest degree of conversion with both LED photoactivation modes. For this resin a 28% decrease in maximum rate was observed and the time to reach its highest rate was almost 2.3 times higher than when the soft-start photoactivation light curing was used. Z-350flow resin recorder a higher maximum rate using the soft-start mode rather than the standard mode. In contrast, the Z-250 showed a higher value using the standard mode. Although Z-250 and Z-350 showed a higher total degree of conversion effectiveness using the soft-start mode, RelyX and Z-350flow achieved a higher value using the standard mode.

Avaliação da adaptação marginal de diferentes tipos de restaurações obtidas por CAD/CAM e métodos convencionais

The past few decades have brought many changes to the dental practice and the technology has become ready available. The result of a satisfactory rehabilitation treatment basically depends on the balance between biological and mechanical factors. The marginal adaptation of crowns and prosthetic structures is vital factor for long-term success. The development of CAD / CAM technology in the manufacture of dental prostheses revolutionized dentistry, this technology is capable of generating a virtual model from the direct digital scanning from the mouth, casts or impressions. It allows the planning and design of the structure in a computered software. The virtual projects are obtained with high precision and a significant reduction in clinical and laboratory time. Thus, the present study (Chapters 1, 2 and 3) computed microtomography was used to evaluate, different materials, different CAD/CAM systems, different ways of obtaining virtual model (with direct or indirect scanning), and in addition, also aims to evaluate the influence of cementing agent in the final adaptation of crowns and copings obtained by CAD / CAM. Furthermore, this study (Chapter 4, 5 and 6) also aims to evaluate significant differences in vertical and horizontal misfits in abutment-free frameworks on external hexagon implants (HE) using full castable UCLAs, castable UCLAs with cobalt-chromium pre-machined bases and obtained by CAD / CAM with CoCr or Zirconia by different scanning and milling systems. For this, the scanning electron microscopy and interferometry were used. It was concluded that the CAD / CAM technology is capable to produce restorations, copings and screw-retained implant-supported frameworks in different materials and systems offering satisfactory results of marginal accuracy, with significative reduction in clinical and laboratory time.

Avaliação in vitro da adaptação marginal e interna de coroas de cerâmica e resina composta fabricadas com o sistema CAD/CAM utilizando duas câmeras intraorais de moldagem digital

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Ciências da Saúde, 2015.

Correlation between margin fit and microleakage in complete crowns cemented with three luting agents

Microleakage can be related to margin misfit. Also, traditional microleakage techniques are time-consuming. This study evaluated the existence of correlation between in vitro margin fit and a new microleakage technique for complete crowns cemented with 3 different luting agents. Thirty human premolars were prepared for full-coverage crowns with a convergence angle of 6 degrees, chamfer margin of 1.2 mm circumferentially, and occlusal reduction of 1.5 mm. Ni-Cr cast crowns were cemented with either zinc phosphate (ZP) (S.S. White), resin-modified glass-ionomer (RMGI) (Rely X Luting Cement) or a resin-based luting agent (RC) (Enforce). Margin fit (seating discrepancy and margin gap) was evaluated according to criteria in the literature under microscope with 0.001 mm accuracy. After thermal cycling, crowns were longitudinally sectioned and microleakage scores at tooth-cement interface were obtained and recorded at ×100 magnification. Margin fit parameters were compared with the one-way ANOVA test and microleakage scores with Kruskal-Wallis and Dunn's tests (alpha=0.05). Correlation between margin fit and microleakage was analyzed with the Spearman's test (alpha=0.05). Seating discrepancy and marginal gap values ranged from 81.82 µm to 137.22 µm (p=0.117), and from 75.42 µm to 78.49 µm (p=0.940), respectively. Marginal microleakage scores were ZP=3.02, RMGI=0.35 and RC=0.12 (p<0.001), with no differences between RMGI and RC scores. The correlation coefficient values ranged from -0.27 to 0.30 (p>0.05). Conclusion: Margin fit parameters and microleakage showed no strong correlations; cast crowns cemented with RMGI and RC had lower microleakage scores than ZP cement.

Microleakage in conservative cavities varying the preparation method and surface treatment

OBJECTIVE: To assess microleakage in conservative class V cavities prepared with aluminum-oxide air abrasion or turbine and restored with self-etching or etch-and-rinse adhesive systems. Materials and Methods: Forty premolars were randomly assigned to 4 groups (I and II: air abrasion; III and IV: turbine) and class V cavities were prepared on the buccal surfaces. Conditioning approaches were: groups I/III - 37% phosphoric acid; groups II/IV - self-priming etchant (Tyrian-SPE). Cavities were restored with One Step Plus/Filtek Z250. After finishing, specimens were thermocycled, immersed in 50% silver nitrate, and serially sectioned. Microleakage at the occlusal and cervical interfaces was measured in mm and calculated by a software. Data were subjected to ANOVA and Tukey's test (α=0.05). RESULTS: Marginal seal provided by air abrasion was similar to high-speed handpiece, except for group I. There was SIGNIFICANT difference between enamel and dentin/cementum margins for to group I and II: air abrasion. The etch-and-rinse adhesive system promoted a better marginal seal. At enamel and dentin/cementum margins, the highest microleakage values were found in cavities treated with the self-etching adhesive system. At dentin/cementum margins, high-speed handpiece preparations associated with etch-and-rinse system provided the least dye penetration. CONCLUSION: Marginal seal of cavities prepared with aluminum-oxide air abrasion was different from that of conventionally prepared cavities, and the etch-and-rinse system promoted higher marginal seal at both enamel and dentin margins.

Elastic modulus of posts and the risk of root fracture

The definition of an optimal elastic modulus for a post is controversial. This work hypothesized that the influence of the posts` elastic modulus on dentin stress concentration is dependent on the load direction. The objective was to evaluate, using finite element analysis, the maximum principal stress (sigma(max)) on the root, using posts with different elastic modulus submitted to different loading directions. Nine 3D models were built, representing the dentin root, gutta-percha, a conical post and the cortical bone. The softwares used were: MSC.PATRAN2005r2 (preprocessing) and MSC.Marc2005r2 (processing). Load of 100 N was applied, varying the directions (0 degrees, 45 degrees and 90 degrees) in relation to the post`s long axis. The magnitude and direction of the sigma(max) were recorded. At the 45 degrees and 90 degrees loading, the highest values of sigma(max) were recorded for the lowest modulus posts, on the cervical region, with a direction that suggests debonding of the post. For the 0 degrees loading, the highest values of sigma(max) were recorded for higher modulus posts, on the apical region, and the circumferential direction suggests vertical root fracture. The hypothesis was accepted: the effect of the elastic modulus on the magnitude and direction of the sigma(max) generated on the root was dependent on the loading direction.