Correlation between 2D and 3D measurements of cement space in CAD-CAM crowns.

STATEMENT OF PROBLEM: Although the 2D analysis of prosthesis cementation space has been popular, its correlation with volumetric comparison (3D data) of cement space is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the cement space in computer-aided design and computer-aided manufacturing (CAD-CAM) crowns of different materials and correlate 2D measurements of cement space with their corresponding 3D values (volume of cement space) by using microcomputed tomography (µCT) analysis of regions of interest. MATERIAL AND METHODS: Ten molar crowns were milled in lithium disilicate (LD), resin nanoceramic (RN), and zirconia (Z) ceramics. Silicone replicas were produced and used as the analog cement layer and scanned with a desktop X-ray microfocus CT scanner. Twenty-eight slices were evaluated in 3 regions: marginal, axial, and occlusal (n=84 measurement points/specimen). After 3D reconstruction of the cement space, the volume was calculated. Data were statistically evaluated through 2-way ANOVA and Bonferroni test (α=.05). The Pearson correlation test was used to investigate the correlation between the 2D and 3D data. RESULTS: The volumes of the occlusal (LD 10 ±1 mm3; RN 9 ±1 mm3) and axial regions (LD 9 ±2 mm3; RN 8 ±1 mm3) were significantly higher than the volume of the marginal region for LD and RN specimens (LD 6 ±2 mm3; RN 4 ±1 mm3) (both P<.001). For the Z group, the axial region had the highest volume (19 ±2 mm3), followed by the volumes of the occlusal (15 ±1 mm3) and marginal regions (12 ±1 mm3). The Pearson correlation test determined a moderate positive correlation of the marginal area (r=0.606, P<.001) and of the axial region (r=0.588, P<.001). However, a moderate negative correlation was found between volume and thickness of the occlusal area (r=-0.437, P=.016). CONCLUSIONS: Z showed more volume of cement space, as well as thicker cement space than LD and RN. The µCT analysis is an efficient method of analyzing cement thickness and volume in ceramic crowns at the selected regions of interest. A moderate positive correlation was found between the 2D and 3D analyses for the axial and marginal regions of ceramic crowns.

Comparison of marginal adaptation and internal fit of monolithic lithium disilicate crowns produced by 4 different CAD/CAM systems.

OBJECTIVES: To evaluate the marginal adaptation and internal space of crowns produced by 4 CAD/CAM systems using microcomputed tomography (µCT) and replica technique (RT). MATERIALS AND METHODS: Monolithic lithium disilicate crowns were milled (Ceramill, Cerec, EDG, and Zirkonzahn) (n = 10). The cement film obtained with low viscosity silicone was scanned by the µCT system and captured by a stereomicroscope, according to RT. Two-way ANOVA followed by Tukey's test were used for statistical analysis (α = 0.05). A uniformity index (UI) was idealized to describe the distribution of crowns' internal space and submitted to the Kruskal-Wallis and Tukey's test (α = 0.05). The correlation between µCT and RT was performed by Pearson's Correlation Coeficient (α = 0.05). RESULTS: Marginal adaptation and internal space were statistically significant different between the experimental groups for the µCT and RT (p < 0.05). The medians of the 4 systems tested were within clinically acceptable range and the mean (± SD) highest marginal discrepancy was recorded in the Ceramill group at 133.0 ± 71.5 µm (µCT) and 90.6 ± 38.5 µm (RT). For internal fit, the UI disclosed a better distribution of the internal space for the Zirkonzahn group (p < 0.001). There was a strong correlation between the methods (p = 0.01 and r = 0.69). CLINICAL RELEVANCE: Because of the variability of the CAD/CAM systems available, evaluating their accuracy is of clinical interest. The 4 systems are capable to produce restorations adaptated within clinically appropriate levels. The µCT and RT are efficient adaptation methodologies.

Analysis of correlation between optical and microtomography measurements of cementation space in CAD-CAM ceramic crowns.

STATEMENT OF PROBLEM: Identical computer-aided design (CAD) parameters may be used to mill a variety of ceramic materials for computer-aided design and computer-aided manufacture (CAD-CAM) crowns. Whether milled crown spacing matches the designed parameters when more than a single evaluation method is applied is unknown. PURPOSE: The purpose of this in vitro study was to correlate the stereomicroscope and the microcomputer tomography (µCT) 2-dimensional analysis of the cementation space with the replica technique in assessing 3 different ceramic materials. MATERIAL AND METHODS: The specimens were milled in lithium disilicate, resin nanoceramic, and zirconia (n=30). The cement space was measured at the marginal, axial, and occlusal regions. One hundred twenty measurements of each material were used to correlate the methodologies. Data were statistically evaluated with 2-way repeated measures ANOVA and the Tukey test (α=.05). The Pearson correlation coefficient was used for each region for both methodologies (µCT and optical microscopy) separately. RESULTS: For the µCT analysis, no differences were observed (P>.05) among the materials, but the axial region showed a positive correlation with the marginal (r=0.957) and occlusal regions (r=0.349); the same was observed between the occlusal and marginal regions (r=0.338). However, for stereomicroscope evaluation, resin nanoceramic and zirconia present similar cementation space (P=960), both being different from lithium disilicate (P<.05). The marginal region presented a positive correlation with axial (r=0.149) and occlusal regions (r=0.344), but the axial region showed negative correlation with the occlusal surface (r=-0.205). CONCLUSIONS: The measurements of the scanned replicas were accurate when thinner sections were under measurement. Although the same space parameters were set in the CAD software program, definitive internal dimensions varied among the milled crowns.

Prótese total mandibular imediata sobre implantes cone-morse / Immediate mandibular full arch prosthesis with Morse taper connection implant: clinical case

A perda total dos dentes ainda é um problema enfrentado por grande parcela da população. Nesse sentido, a Odontologia vem desenvolvendo novos métodos para a reabilitação desses pacientes. As próteses totais mucossuportadas foram amplamente utilizadas sem apresentarem, no entanto, estabilidade e retenção satisfatórias, principalmente na mandíbula. Com os estudos desenvolvidos por Brånemark, que culminaram com o aparecimento dos implantes osseointegráveis, um novo conceito de tratamento de pacientes desdentados totais surgiu: próteses totais implantossuportadas. A partir desse conceito, modificações foram realizadas no protocolo original com o intuito de tornar o tratamento mais rápido, efetivo, barato e menos traumático. Assim, pesquisas foram desenvolvidas para viabilizar o carregamento imediato dos implantes. Outro novo conceito que busca a melhora dos resultados em reabilitações orais é o sistema cone-morse, que apresenta maior resistência mecânica, melhor distribuição e transmissão de forças ao longo do implante para o tecido ósseo, redução do gap, com diminuição da possiblidade de invasão bacteriana na interface do implante intermediário, além da redução do afrouxamento e fraturas de parafusos. Fundamentado nessas considerações, este artigo tem como objetivo apresentar um caso clínico de reabilitação com prótese total imediata implantossuportada por implantes do tipo cone-morse na mandíbula. O resultado mostrou-se bastante satisfatório tanto em relação à estética quanto à função e, principalmente, ao conforto do paciente.

The edentulous condition is still a problem faced by most of the population. In this sense, dentistry has developed new methods for the rehabilitation of these patients. Initially, mucoussupported total prostheses have been widely used however without demonstrating satisfactory stability and retention, particularly in the jaw. With the studies developed by Brånemark culminating in the appearance of modern dental implants, a new concept emerged to treat edentulous patients: total implant-supported fixed prosthesis. From this concept, modifications were made in the original protocol in order to make the treatment faster, effective, inexpensive, and less traumatic. Thus, research has been developed to enable the immediate implant activation. Another new concept that aims to provide better results in the oral rehabilitation is the Morse taper system that has greater mechanical strength, better force distribution and transmission along the implant to the bone tissue, reducing the gap with less chance of bacterial invasion in the prosthetic-implant interface, and still with less loosening and screw fractures. Based on these considerations, this article aims to present a case of an immediate implant-supported mandibular total prosthesis on Morse taper implants. The result was quite satisfactory both in relation to aesthetics, function, but especially for patient's comfort.

Esthetic rehabilitation with zirconia on tooth and morse taper implant: case report / Reabilitação estética em zircônia sobre dente e implante cone morse: caso clínico

Among the ceramic materials used in dentistry, Zirconia presents the ideal opacity for cases where the clinical challenge is to neutralize the difference in the colors of the substrates. The "ceramic steel", so called by some authors, guarantees to Zirconia resistance and hardness similar to a metal, but with aesthetic advantages superior to the metal-ceramic restorations, which can exhibit exposure of the metal band over time. This article describes a complex rehabilitation treatment involving dental elements with different substrates: 11 - vital tooth with large crown damage; 21 ­ endodontically treated tooth and cast metal core; 22 - Morse taper implant. The selection of a completely zirconia-based ceramic system allowed masking the different conditions of substrates, so achieving the esthetic expectations. Moreover, considering the patient's high smile line, excellent gingival esthetics was obtained with an internal connection Morse taper implant associated with an individualized anatomic abutment.

Dentre os materiais cerâmicos utilizados na Odontologia, a Zircônia apresenta a opacidade ideal para os casos em que o desafio clinico é neutralizar a diferença nas cores dos substratos. O "aço cerâmico", assim chamado por alguns autores, garante à Zircônia resistência e dureza semelhantes a um metal, mas com vantagens estéticas superiores às restaurações metalocerâmicas, as quais podem apresentar exposição da cinta metálica ao longo do tempo. Este artigo descreve um tratamento reabilitador complexo, envolvendo elementos dentários com diferentes substratos: 11 - dente vital com ampla destruição coronária; 21 - dente com tratamento endodôntico e núcleo metálico fundido; 22 ­ ausente, reabilitado com implante do tipo cone morse. A seleção do sistema totalmente cerâmico à base de zircônia, permitiu mascarar as diferentes condições dos substratos atingindo as expectativas estéticas. Além disso, diante do sorriso alto gengivoso presente neste caso, a excelência na estética gengival foi obtida utilizando implante com conexão interna do tipo cone morse associado a um pilar anatômico individualizado.

Técnica dos 5 dedos ­ desmistificando a seleção dos pilares protéticos nas próteses implanto retidas / 5-Fingers technique: desmystifying the selection of prosthetic abutments in implanted supported prosthesis

A seleção de pilares protéticos é um desafio para o cirurgião-dentista, sendo essencial para o sucesso da reabilitação oral sobre implantes, visando à previsibilidade e longevidade. Essa seleção deve obedecer a um planejamento multidisciplinar reverso para obter sucesso estético e biomecânico. Este trabalho tem como finalidade apresentar uma técnica idealizada para desmistificar a escolha de componentes protéticos sobre implantes disponíveis no mercado, auxiliando o cirurgião-dentista a selecionar corretamente os pilares protéticos, bem como suas indicações e contraindicações. A Técnica dos 5 dedos atribui à cada dedo da mão um componente protético e também à cada dedo um fator a ser verificado nessa escolha: distância interoclusal, sulco periimplantar, angulação, elementos isolados ou múltiplos, próteses cimentadas ou aparafusadas. Permitindo, portanto, uma seleção objetiva e simples (AU).

The selection of prosthetic abutments is a challenge for the dentist, being essential for the success of oral rehabilitation on implants, aiming predictability and longevity. This selection must obey a reverse multidisciplinary planning for aesthetic and biomechanical success. This work aims to present an idealized technique to demystify the choice of prosthetic components on implants available in the market, helping the dentist to correctly select prosthetic abutments, as well as their indications and contraindications. The 5-fingers technique defines a prosthetic component to each finger and also to each finger a factor to be checked in this choice: interocclusal distance, periimplantar sulcus, angulation, isolated or multiple elements, cemented or bolted prosthesis. Thus allowing an objective and simple selection (AU).

Correlação da tensão no intermediário e as medidas de comprimento, altura e angulação de infraestruturas de próteses sobre implantes / Correlation of abutment tension and measures of length, height and angle of implant-supported prostheses framework

A adaptação passiva e estabilidade têm sido descritos como pré-requisitos importantes na escolha dos materiais e técnicas de confecção em prótese implantossuportada. A proposta deste trabalho foi estudar, com auxílio dos strain gauges, a deformação média gerada nos intermediários após a aplicação de carga axial em infraestruturas confeccionadas por três diferentes materiais. Além disso, através da microscopia confocal a laser, avaliar as medidas de comprimento, altura e angulação desses espécimes e mini pilares. Esses dados foram submetidos à análise estatística, a fim de encontrar possível correlação entre a deformação gerada e as medidas internas das infraestruturas com as externas dos intermediários em que foram parafusadas. Para essa investigação foi utilizado um modelo em poliuretano com dois implantes, hexágono externo, posicionados nas áreas dos dentes 43 e 45. A partir deste modelo, 12 infraestruturas de três elementos foram fabricadas e divididas em 3 grupos (n=4) de acordo com a técnica utilizada: (C) fundição convencional em Ni-Cr; (U) usinada em zircônia por CAD/CAM e (S) sinterizada a laser em Co-Cr pelo CAD/CAM. Durante a aplicação de carga axial, as tensões geradas foram registradas por extensômetros unidos aos intermediários, e avaliadas quantitativamente e qualitativamente. De maneira geral, houve um predomínio de áreas de compressão, sendo que as poucas áreas de tração apresentaram baixos valores. O grupo sinterizado a laser foi o único que apresentou forças compressivas para todos os sensores. Os grupos usinado e convencional apresentaram comportamento semelhante, diferindo apenas em uma região. Posteriormente, as infraestruturas e os intermediários foram submetidos à microscopia confocal para avaliação de ângulo, comprimento e altura de suas paredes internas (infraestruturas) e externas (intermediários), nas regiões correspondentes à localização dos strain gauges. Para a angulação, todos os grupos mostraram valores...

The passive adaptation and stability have been described as important prerequisites in the choice of materials and manufacturing techniques in implant-supported prosthesis. The aim of this work was to study, with the aid of strain gauges, the average deformation generated in the abutment, after application of axial load on frameworks made up of three different materials. Besides, through confocal laser microscopy, assess the length, height, and angle of these specimens, and abutment. These data were statistically analyzed in order to find possible correlation between the deformation generated, and the internal measures of the framework and the external measure of the abutments they were screwed on. For this research, a model made of polyurethane with two external hexagon implants, positioned in the areas of teeth 43 and 45 was used. From this model, 12 three-element frameworks were fabricated and divided into 3 groups (n = 4), according to the technique used: (C) conventional Ni-Cr casting; (U) machined zirconia CAD / CAM and (S) laser sintered Co-Cr by CAD / CAM. During application of axial load, the tensions generated were recorded by strain gauges attached to the abutments, and evaluated quantitatively and qualitatively. In general, there was a predominance of compression areas, and the few areas of traction showed low values. The laser sintered group was the only one with compressive forces for all sensors. The milled and conventional groups behaved similarly, differing only in a region. Subsequently, the framework and the abutment were analyzed by confocal microscopy for evaluation of angle, length and height of the inner (framework) and outer (abutment) walls in regions corresponding to the location of strain gauges. For the variable angle, all groups showed similar values among themselves and greater than the abutments. As for the variables length and height, all values were different. Regarding the abutments, the values were higher in height and...