Soft tissue replication in single unit implant impressions-A three dimensional clinical study.

OBJECTIVE: Comparison of soft tissue replication between conventional and digital impressions for definitive single unit implant rehabilitation in the esthetic zone. MATERIALS AND METHODS: Six patients were recruited according to inclusion criteria for this cross-over pilot study and submitted to a conventional silicone implant impression with customized coping and a digital impression with an intraoral scanner. Stereolithography files obtained from the same patient were superimposed with appropriate software and trueness evaluated between methods at predetermined locations (56 in hard and soft tissues and 18 in the emergence profile, per patient). Results were presented as mean root mean square (RMS) ± 95% confidence interval and effect size calculated with Hedges' g ± 95%. Mann-Whitney and Kruskal-Wallis were performed when appropriate and α was set at .05. RESULTS: Trueness between methods equated to 51.08[45.68;56.47] µm and 60.46[52.29;68.62] µm in hard and soft tissues, respectively. Soft tissue replication by intraoral scanner acquisition corresponded to a statistically significant RMS of 243.89[209.15;278.63] µm equating to a Hedges' g of 1.52[1.22;1.82] which corresponded to a large effect size. CONCLUSIONS: The proposed method could be considered for soft tissues assessment and the results suggest that intraoral impression techniques produce statistically significant changes in peri-implant soft tissue replication, although below the clinically detectable threshold. CLINICAL SIGNIFICANCE: The proposed technique allows for the 3D determination of peri-implant tissues changes in digital models with higher sensitivity than visual techniques, thus presenting itself as a promising alternative in clinical studies and that the use of an intraoral scanner obtained significant differences in the soft tissue emergence profile replication when compared with the gold standard.

Influence of Preparation Reconstruction on the Compressive Strength of CAD/CAM Ceramic Inlays.

The aim of this study was to evaluate whether the compressive strength of lithium dissilicate ceramic inlays is influenced by the substrate (dentin or composite resin build-up) and to compare it to nonrestored teeth. Thirty freshly extracted human maxillary third molars were selected and randomly ascribed to three groups (n=10). Standardized Class II MOD preparations were made (bucco-palatal width = 2/3 of the intercuspal width and 2/3 of the width at the tooth equator for the proximal boxes), varying the extension of the preparations (Group 2: preparation limited to tooth structure; Group 3: pulpal floor of the preparation rebuilt with composite resin, IPS Empress Direct, restored with lithium dissilicate CAD/CAM ceramic inlays (e.max CAD) and cemented with a resin cement (Variolink II)). All groups were subjected to compressive strength test (1mm/min crosshead speed). The results showed that the fracture strength of G1 (control group) was significantly higher than G2 and G3, while within these groups there were no statistically significant differences. Both groups restored with lithium dissilicate restorations did not reach the fracture strength of the sound teeth but were statistically equivalent and sufficient to withstand physiologic masticatory forces.

Evaluation of the fracture resistance of premolars with extensive and medium cavity preparations restored with direct restoring systems.

CONTEXT: Studies have been conducted to measure the fracture resistance of restored teeth with the current restorative materials. However, most of those studies disregard the cavity size as an influencing variable. AIMS: To evaluate the fracture resistance of prepared and restored maxillary premolars with medium and large preparations. MATERIALS AND METHODS: Seventy superior and sound premolars were randomly divided: G1 (control) - sound tooth; G2, G3, and G4 received a Class II mesial-occlusal-distal (MOD) preparation with an occlusal box width 1/3 of the intercuspal distance, and were restored with Filtek Z350 XT, IPS Empress Direct, and Charisma Diamond, respectively; G5, G6, and G7 received a Class II MOD preparation with an occlusal box width 2/3 of the intercuspal distance, and were restored with Filtek Z350 XT, IPS Empress Direct, and Charisma Diamond, respectively. After storage in water, at 37°C, the specimens were subjected to a fracture test under compression in a universal testing machine where the loads were applied vertically and at a speed of 0.5 mm/min. STATISTICAL ANALYSIS USED: Data were analyzed with two-way ANOVA and Tukey's multiple comparison post hoc test (P < 0.05). RESULTS: G1 presented a fracture resistance significantly higher (P = 0.005) than any other experimental groups. Among the experimental groups, only G5 showed a significantly low fracture resistance (P = 0.019) when compared to the other groups. For the other resins, the change in intercuspal distance from 1/3 to 2/3 the intercuspal distance did not significantly reduce the fracture resistance (P > 0.05). CONCLUSIONS: The cavity preparation weakens the remaining tooth structure; however, its resistance could be partially restored using direct adhesive restorations.

Randomized clinical trial of 2 nonvital tooth bleaching techniques: A 1-year follow-up.

STATEMENT OF PROBLEM: Controlled clinical trials comparing the effectiveness of the walking bleaching (WB) technique and the inside-outside (I-O) technique used in a short daily regimen are lacking. PURPOSE: The purpose of this randomized clinical trial was to investigate the effectiveness of WB with that of the I-O technique conducted over 4 weeks and to compare color changes after 1 year. MATERIAL AND METHODS: Discolored and endodontically treated anterior teeth received a cervical seal and were randomly divided into groups according to the technique. In the WB group (n=9), a mixture of sodium perborate and 20% hydrogen peroxide was applied in the pulp chambers and replaced weekly up to 4 weeks. For the I-O group (n=8), participants applied 10% carbamide peroxide in the pulp chambers and wore custom-fitted trays for 1 hour per day over 4 weeks. CIELab parameters were obtained using a spectrophotometer at baseline, during bleaching (1, 2, 3, and 4 weeks) and after 1 year. Changes in color (ΔE), lightness (ΔL*), green-red axis (Δa*), blue-yellow axis (Δb*), and absolute color parameters (L*, b*, and a*) for each evaluation time were calculated and analyzed by repeated measures analysis of variance (ANOVA) and post hoc Bonferroni test (α=.05). RESULTS: No significant differences between WB and I-O techniques were observed for ΔE, ΔL*, Δa*, Δb*, L*, a*, or b* values (P>.05); however, significant differences were observed among the evaluation times (P<.05). Color changes observed after 2 weeks were stable after 1 year; ΔL* and Δa* values after 1 year were not significantly different from the 1-week evaluation, and significant changes in Δb* after 3 weeks were maintained at the 1-year follow-up. The same trend was observed for the absolute CIELab color parameters. CONCLUSIONS: Both WB and I-O regimens were similarly effective as shown by significant ΔE after 2 weeks and no color regression after 1 year.

Evaluation of a technique for color correction in restoring anterior teeth.

OBJECTIVE: This study aimed to evaluate the ability of the proposed technique in producing restorations that exhibit mimesis with tooth structure and to define a restorative clinical protocol. MATERIALS AND METHODS: For this study a typodont was used. The right upper central incisor with Class IV lesion was restored with the layering technique (reference tooth, RT). For the left upper central incisor with Class IV lesion, six teeth were restored monochromatically (test teeth, TT), using DA3.5 (n = 3) and DA4 (n = 3) composite resins-resulting in six unsatisfactory color restorations. TT were divided into six groups depending on the color of unsatisfactory restoration and preparation depth. First, a preparation was realized on the labial surface with 0.5 mm, 0.7 mm or 1.0 mm of depth. A second preparation was then performed to reproduce the dentinal mamelons. Next, adhesive procedures were performed and the teeth restored. Opaque halo, opalescent halo and vestibular enamel were then reproduced by the addition of different composite resins. The RT and TT were photographed side by side in typodont to obtain six photographic prints. The photographs of the groups were subjected to visual evaluation by 120 volunteers via a questionnaire. Data were analyzed by the prevalence of answers, and Chi-square test was used to investigate the association between variables at .05 significance. Furthermore, ΔE of groups was evaluated in comparison RT. RESULTS: The results demonstrated that the moderate intensity restorations (DA3.5) with depths of 0.5 mm and 0.7 mm had the highest prevalence of acceptance. For severe intensity restorations (DA4), the preparation depth of 1.0 mm obtained better acceptance. CONCLUSIONS: The technique was able to modify the final color of Class IV restorations, producing satisfactory color restorations. CLINICAL SIGNIFICANCE: This technique can be used for color correction in cases of Class IV restorations, in situations where there is no time for immediate layered restoration, and as a restorative technique.

Influence of Teeth Preparation Finishing on the Adaptation of Lithium Disilicate Crowns.

The polishing step of teeth preparations for crowns is a step often performed, so that there is an increased time during the clinical procedure. The aim of this study is to evaluate the marginal and internal adaptation of all-ceramic CAD/CAM lithium disilicate crowns in polished preparations for crown and nonpolished preparations for crowns. For this purpose, 20 first molars were selected, which were divided into two groups (n = 10) G1, teeth that received surface roughening similar to preparation without polishing, and G2 (control), polished preparations. After the preparations were completed the teeth were scanned (Cerec Bluecam, Sirona, Bensheim, Germany), and the crowns were designed and machined using CAD/CAM technology (Sirona, Bensheim, Germany). The adaptation of the pieces was evaluated using polyvinyl siloxane replicas and stereomicroscope photographs with 70x magnifications. The normality test indicated a nonnormal result, so a Man-Whitney nonparametric test was performed. One out of the 24 measured regions showed a statistically significant difference (p = 0.0494). With this study it can be concluded that crowns fabricated by CAD/CAM technology performed on unpolished preparations are not influenced by the internal marginal adaptation and the ceramic part and are different from polished preparations.

Evaluation of microtensile bond strength of self-etching adhesives on normal and caries-affected dentin.

The purpose of this study was to evaluate the µTBS (microtensile bond strength) of currently available self-etching adhesives with an experimental self-etch adhesive in normal and caries-affected dentin, using a portable hardness measuring device, in order to standardize dentin Knoop hardness. Normal (ND) and caries-affected dentin (CAD) were obtained from twenty human molars with class II natural caries. The following adhesive systems were tested: Mega Bond (MB), a 2-step self-etching adhesive; MTB-200 (MTB), an experimental 1-step self-etching adhesive (1-SEA), and two commercially available one-step self-etching systems, G-Bond Plus (GB) and Adper Easy Bond (EB). MB-ND achieved the highest µTBS (p<0.05). The mean µTBS was statistically lower in CAD than in ND for all adhesives tested (p<0.05), and the 2-step self-etch adhesive achieved better overall performance than the 1-step self-etch adhesives.

Modeling and validation of a 3D premolar for finite element analysis / Modelagem e validação 3D de um premolar para análise de elementos finitos

Introduction: The development and validation of mathematical models is an important step of the methodology of finite element studies. Objective: This study aims to describe the development and validation of a three-dimensional numerical model of a maxillary premolar for finite element analysis. Material and method: The 3D model was based on standardized photographs of sequential slices of an intact premolar and generated with the use of SolidWorks Software (Dassault, France). In order to validate the model, compression and numerical tests were performed. The load versus displacement graphs of both tests were visually compared, the percentage of error calculated and homogeneity of regression coefficients tested. Result: An accurate 3D model was developed and validated since the graphs were visually similar, the percentage error was within acceptable limits, and the straight lines were considered parallel. Conclusion: The modeling procedures and validation described allows the development of accurate 3D dental models with biomechanical behavior similar to natural teeth. The methods may be applied in development and validation of new models and computer-aided simulations using FEM.

Introdução: O desenvolvimento e validação de modelos matemáticos é uma importante etapa da metodologia de estudos de elementos finitos. Objetivo: Este estudo tem o objetivo descrever o desenvolvimento e validação de um modelo numérico tridimensional de um pré-molar superior para análise em elementos finitos. Material e método: Fotografias padronizadas de cortes sequenciais de um pré-molar hígido serviram de referência para o desenvolvimento do modelo 3D, que foi construído por meio do programa SolidWorks (Dassault, França). A fim de validar o modelo testes de compressão e simulação numérica foram realizados. Os gráficos de carga versus deslocamento de ambos os ensaios foram comparados visualmente, a percentagem de erro calculada e homogeneidade dos coeficientes de regressão testada. Resultado: Um modelo 3D preciso foi desenvolvido e validado, uma vez que os gráficos apresentavam-se visualmente semelhantes, o percentual de erro ficou dentro dos limites aceitáveis e as retas foram consideradas paralelas. Conclusão: Os procedimentos de modelagem e validação descritos permitem o desenvolvimento de modelos dentários 3D precisos com comportamento biomecânico semelhante aos dentes naturais. Os métodos podem ser aplicados no desenvolvimento e validação de novos modelos e estudos de simulações computacionais por meio do MEF.

Clinical evaluation of different desensitizing agents in home-bleaching gels.

STATEMENT OF PROBLEM: The influence of different compositions of desensitizing agents in whitening gels should be evaluated. PURPOSE: The purpose of this clinical trial was to compare the effectiveness of 4 carbamide peroxide (CP)-based bleaching gels containing desensitizing agents regarding the degree of bleaching, tooth sensitivity, degree of participant satisfaction, and gingival irritation. MATERIAL AND METHODS: The maxillary arch of the 50 participants was bleached using a split mouth, home-bleaching technique. The participants were divided into 2 groups: G1, 10% CP (Opalescence PF; Ultradent Products, Inc) (right) and 10% CP (Power Bleaching 10%; BM4) (left); and G2, 15% CP (Opalescence PF) (right) and 16% CP (Power Bleaching 16%) (left). Each gel was used in a 2-hour daily regimen for 45 days. The shade of the 6 maxillary anterior teeth was recorded with a shade guide and spectrophotometer at baseline, and after 15, 30, 45, and 180 days of treatment. Statistical differences were analyzed with ANOVA for repeated measures followed by the Bonferroni and Student t tests (α=.05). Tooth sensitivity was evaluated with a visual analog scale (rated on a 0 to 10 scale). Participant satisfaction was evaluated by using participant reports of their personal satisfaction or dissatisfaction with the shade. Gingival irritation was evaluated using the Löe index scores. RESULTS: Color change was found to be statistically significant for all treatment periods evaluated, both by the objective and the subjective analyses, regardless of the composition and the concentration of the bleaching agent (P<.001). After 45 days, all participants were satisfied with the shade obtained. No clinically diagnosed gingival irritation was noted. Neither of the 10% CP products caused sensitivity during treatment, and 16% CP containing 3% potassium oxalate showed lower sensitivity than 15% CP containing potassium nitrate. CONCLUSION: The association of 3% potassium oxalate with fluoride was effective in reducing tooth sensitivity during and after bleaching, particularly with the 16% CP product, and did not compromise the effectiveness of treatment.

Comparison of treatment time versus patient satisfaction in at-home and in-office tooth bleaching therapy.

STATEMENT OF THE PROBLEM: There are different approaches and treatment times to achieve tooth whitening. PURPOSE: The purpose of this study was to evaluate the efficacy of different agents and the treatment time required to achieve participant satisfaction with at-home and in-office tooth whitening. MATERIAL AND METHODS: Thirty participants were selected based on the shade of the anterior teeth (between A2 and A3.5; Vita Classic Shade Guide). Each participant received both in-office and at-home bleaching agents in a split-mouth design at both arches. In-office bleaching was performed in the maxillary quadrants, applying 35% hydrogen peroxide (HP35%) (right) and 35% HP with calcium (HP35%Ca) (left) for 40 minutes/week. Home bleaching was performed in mandibular quadrants using carbamide peroxide 10% (CP10%) (right) and CP22% (left) for 2 hours/day. Bleaching treatments were performed until participant satisfaction was achieved (maximum 6 sessions [S] in the dental office or 6 weeks [W] in the home). The shade was measured with a spectrophotometer before treatment, then at 2 and 4 weeks, and at the last week for at-home bleaching; and 1 week after the second, fourth, and last sessions for in-office bleaching. Student t and Tukey-Kramer tests were used (α=.05). RESULTS: All bleaching agents were effective for vital tooth whitening. No significant differences were observed for color changes between CP10% and CP22% or between HP35% and HP35%Ca for all periods. Treatment times required to achieve patient satisfaction for the in-office bleaching technique were 4S (12 participants), 5S (10 participants), and 6S (8 participants); and 4W (6 participants), 5W (8 participants), and 6W (16 participants) for the at-home bleaching technique. CONCLUSIONS: Treatment time to participant satisfaction ranged from 4 to 6 weeks regardless of the bleaching agent used in at-home and in-office therapy.

Cerâmicas anteriores: como e quando indicá-las / Anterior ceramics: how and when to indicate

Desde a introdução do primeiro sistema bem-sucedido de cerâmica fundida a metal, há uma crescente demanda de restaurações cerâmicas, pois se trata de um material de grande propriedade estética, devido à disponibilidade de uma ampla gama de matizes e efeitos de translucidez. O desenvolvimento das cerâmicas levou a uma gama maior de indicações e transformou o desenho dos preparos clássicos de facetas em desenhos estendidos e orientados pelo defeito prévio do remanescente dental, as chamadas “facetas estendidas”. No entanto, mesmo que atualmente as facetas clássicas e estendidas possam ser soluções alternativas aos preparos para coroa total, elas não devem ser sempre a primeira escolha para todas as situações clínicas, porque vários fatores devem ser considerados antes da elaboração de um plano de tratamento. Portanto, fazer a escolha certa entre coroas, facetas clássicas e estendidas na dentição anterior para cada situação clínica é elemento-chave para um tratamento conservador e longevo. Neste artigo uma classificação de acordo com o conteúdo das cerâmicas odontológicas é descrita, e são abordadas importantes considerações baseadas em evidência, relacionadas ao plano de tratamento de reabilitações nos dentes anteriores com coroas e facetas cerâmicas...

Since the introduction of the first porcelain-fused-to-metal system, there has been a growing demand for ceramic restorations, since it is a material that provides good aesthetics, wide range of shades and translucency effects. The development of new reinforced ceramics has led to a broader range of indications and changed the conventional veneer preparations into extended defect-oriented preparation designs, the so called “extended veneers”. However, even though classical and extended veneers can be an alternative to full crown preparations, they should not always be the first choice for every clinical situations because several factors must be taken into consideration before elaborating a treatment planning. Therefore, making the right choice between all-ceramic crowns, conventional and extended veneers in the anterior dentition is key for a conservative and long-lasting treatment for each individual situation. This article describes a classification of the ceramic systems, addressing important evidence-based considerations regarding the treatment planning rehabilitation of the anterior dentition using all-ceramic crowns and veneers...

Effect of ceramic thickness and composite bases on stress distribution of inlays--a finite element analysis.

The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred.

Effect of Ceramic Thickness and Composite Bases on Stress Distribution of Inlays - A Finite Element Analysis

The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred.

O objetivo do estudo foi avaliar o efeito da profundidade da cavidade, da espessura da cerâmica e da presença de bases de resina, com os diferentes módulos de elasticidade na distribuição de tensões de von Mises em inlays cerâmicos. Modelos geométricos tridimensionais foram desenvolvidos com o software SolidWorks. As diferenças entre os modelos foram: a profundidade da parede pulpar, a espessura da cerâmica e a presença de bases de resina composta com diferentes espessuras e módulos de elasticidade. Os modelos geométricos foram engastados nas superfícies proximais e base do osso maxilar e uma carga de 100 Newton foi aplicada. O padrão de distribuição de tensões foi analisado com diagramas de tensão de von Mises. O valor de tensão máxima de von Mises foi variável entre os modelos e situou-se na faixa entre 176 e 263 MPa. O maior valor foi encontrado nos modelos restaurados com bases de resina composta de 1 mm e inlay cerâmico de 1 mm de espessura. Valores intermediários (249-250 MPa) ocorreram nos modelos com bases de resina composta de 2 mm e inlays de 1 mm de espessura e nos modelos com bases de resina composta de 1 mm e inlays de 2 mm. Os menores valores foram observados nos modelos restaurados exclusivamente com inlay cerâmico (176-182 MPa). Verificou-se que inlays com maior espessura distribuem o estresse de forma mais favorável e bases com baixo módulo de elasticidade aumentam a concentração de tensões na superfície interna do inlay de cerâmica. O aumento da espessura do material cerâmico tende a apresentar uma distribuição de tensões mais favorável, principalmente quando cimentadas diretamente sobre o preparo cavitário, sem a existência de materiais intermediários. Em situações em que o emprego de materiais de base é necessária, deve-se preferir resinas compostas com alto módulo de elasticidade e espessura reduzida.

Two-year clinical performance of a two-step etch-and-rinse adhesive in non-carious cervical lesions: Influence of subject's age and dentin etching time.

AIM: The aim of this study was to evaluate the influence of the subject's age and dentin etching time on the clinical performance of a two-step etch-and-rinse adhesive in class V non-carious cervical lesions (NCCLs). MATERIALS AND METHODS: Forty patients with NCCLs (classified as degrees 2 and 3 of dentin sclerosis) were enrolled in this study. The lesions were selected and assigned into two groups (n = 70/group) according to the subject's age: (G1) between 21-35 years old and (G2) between 40-54 years old. Each group was randomly divided into two subgroups (n = 35/group) according to dentin etching time using recommended application time (15 s) and an extended application time (30 s). A total of 140 restorations with XP Bond (Dentsply DeTrey, Germany) were placed. The composite resin Esthet X (Dentsply) was placed incrementally. All restorations were evaluated using the modified USPHS criteria. Data was analyzed by the McNemar and chi-square tests (p < 0.05). RESULTS: At the end of 2 years, 132 restorations (94.2% recall rate) were evaluated. The 24-month retention rates (%) were 93.5 for G1(15), 97.1 for G1(30), 93.9 for G2(15), and 97.0 for G2(30). There were no statistical differences in the retention rates in each recall period among groups. CONCLUSION: For the selected age groups, neither the subject's age nor the etching time had any influence on the clinical performance of XP Bond adhesive in NCCLs over a 24-month period. CLINICAL RELEVANCE: The clinical effectiveness of the XP Bond was excellent after 2 years of clinical service. Long-term clinical evaluations are necessary to confirm this finding.

Dupla polarização da luz: um meio para entendermos os dentes naturais: parte 2 / Dual polarization of light: a means to understand the natural teeth: part 2

A óbvia diferença estrutural entre o esmalte humano e os materiais restauradores estéticos explica a alta dificuldade de emulação da cor dental, pois esses se relacionam com a luz natural de maneiras extremamente distintas. O esmalte dental, quando iluminado, produz efeitos ópticos baseados nos princípios de birrefringência. Esse tecido interage com a luz e a decompõe em distintos feixes de diferentes comprimentos de onda, o que gera mudanças dinâmicas de cor, dependendo do ângulo de incidência da luz e de sua trajetória dentro do corpo prismático tridimensional do esmalte. Nesse sentido, é necessário estudar os meios para explorar e entender melhor como os dentes naturais têm suas expressões cromáticas estabelecidas. Neste segundo artigo sobre dupla polarização da luz, a metodologia necessária para a produção dessa técnica de extração e registro dos variados efeitos ópticos do esmalte é descrita.

The obvious structural difference between human enamel and the esthetic restorative materials explains the high complexity in achieving shade matching and color reproduction, since such substrates interact with natural light through highly different ways. Enamel yields optical effects based on principles of birefringence when illuminated. The tissue decomposes light into distinct rays and wavelengths which produces dynamic hue changes depending on the light incidence angle and on its trajectory within the tridimensional prismatic enamel body. Accordingly, it is necessary further studies on the interrelation between teeth and light, in order to better explore and understand how the chromatic expressions of natural teeth are set. The aim of this second paper on double light polarization was to describe the methodology required to carry out this technique of obtaining and recording the multiple optical effects of natural teeth.

Dupla polarização da luz: um meio para vermos e entendermos os dentes naturais: parte 1 / Double light polarization: a means to see and understand the natural teeth: part 1

Uma série de dois artigos (Parte 1 e 2) sobre dupla polarização da luz é apresentada. Nesta primeira parte (Parte 1), destaque especial é dado às fotografias obtidas pela técnica de dupla polarização da luz, bem como aos múltiplos detalhes de translucidez dos tecidos duros de dentes naturais extraídos. Uma fonte de luz branca, uma câmera fotográfica Nikon D60, uma lente Nikkor 105 mm e filtros de polarização da luz (HOYA 62 mm PL- -CIR) foram utilizados para a obtenção das fotografias aqui apresentadas...

This two-article series (Parts 1 and 2) on double light polarization is here presented. Part 1 gives special emphasis to those photographs obtained through the technique double light polarization, as well as the multiplicity of translucent details from the hard tissue of extracted natural teeth. A source of white light, a photographic camera (Nikon D60), a 105 mm macro lens (Nikor) and light polarization filters (Hoya 62mm pl-cir philippines) were used for obtaining the photographs presented herein...

Silorane adhesive system: a case report.

Silorane-based composite resin requires a specific adhesive system: a 2-step self-etching adhesive. Clinical protocols are well established and are based on the principles of adhesion to mineralized dental tissues. In this paper, we present a clinical application of the silorane adhesive system in a class-II restoration using silorane-based composite resin.

Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay.

The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n=10): G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p>0.05). All specimens withstood the fatigue protocol (185,000 cycles), representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.

Lesões cervicais não cariosas (LCNCs): parte II: sugestões para a clínica diária / Non carious cervical lesions (NCCLs): part II: suggestions for the daily practice

As LCNCs apresentam etiologia multifatorial e expressão crescente na clínica diária. Seu estudo é cada vez mais necessário, para possibilitar correto diagnóstico, tratamento e prevenção. A resina composta apresenta–se como melhor material para restaurar as LCNCs com estética e funcionalidade. Outra grande vantagem dela é o selamento da dentina cervical exposta, que elimina a sensibilidade e traz, assim, conforto ao paciente. Todavia, a adoção de um protocolo criterioso, especialmente nas etapas do isolamento do campo operatório, aplicação do sistema adesivo, inserção da resina composta, acabamento e polimento, é essencial para o sucesso restaurador. Sendo assim, a parte II desta série apresenta dois protocolos clínicos como sugestões para se obterem resultados mais previsíveis, com base em uma interpretação conservadora da literatura.

NCCLs presente multifactorial etiology and increased prevalence in the daily practice. Its study is increasingly necessary to enable correct diagnosis, treatment and prevention. Composite resin has shown to be material of choice to restore NCCLs with esthetics and function. Another great advantage is sealing of exposed cervical dentin, eliminating tooth sensitivity, thus bringing comfort to the patient. However, the adoption of a careful protocol, especially in the steps of isolation of the operative field, application of adhesive system, insertion of composite resin, finishing and polishing, is essential for successful restorations. Therefore, the second part of this three-part series presents two suggestions of clinical protocols to obtain more predictable results, based on a conservative approach of the literature.

Lesões cervicais não cariosas (LCNCs). Parte 1: considerações básicas / Non carious cervical lesions (NCCLs). Part 1: basic considerations

As lesões cervicais não cariosas (LCNCs) são cada vez mais prevalentes, tanto em jovens quanto em adultos e idosos. Elas são consideradas um dos novos desafios da odontologia. Inúmeras controvérsias ainda perduram na literatura, dificultando o diagnóstico e tratamento desse tipo de lesão. Diversos materiais têm sido utilizados na restauração delas, sendo as resinas compostas a principal opção. Este artigo, que é uma parte de dois, apresenta uma breve revisão da literatura sobre as LCNCs. Nesta parte, são abordados pontos importantes, como definição, epidemiologia, implicações clínicas, tratamento, variáveis que influenciam a adesão e a seleção do material e por que utilizar resina composta.

Non carious cervical lesions (NCCLs) became increasingly prevalent, both in young and adults, and are considered a new challenge in Dentistry. Numerous controversies still exist in the literature, difficulting the diagnosis and treatment of this type of lesion. Various materials have been used to restore these lesions, and composite resins are the material of choice. This article, the first of two-part study, presents a brief review of the literature on NCCLs. This will address important points, such as definition, epidemiology, clinical implications, treatment, variables that influence the adhesion, material selection and why using composite resins.