Impression in fixed prosthesis: fabrication of impression cap

O objetivo do artigo foi descrever a técnica de confecção de uma moldeira individual para moldagem de preparo total para coroa, também conhecida como casquete de moldagem, além de discutir fatores e princípios envolvidos no tema. Na presente técnica, é obtido um modelo de gesso da região do preparo e um alívio em cera é realizado em suas paredes axiais. Após a aplicação de um isolante, o casquete é confeccionado utilizando pó e líquido de resina acrílica ativada quimicamente indicada para confecção de restaurações provisórias. A resina acrílica é aplicada na região cervical utilizando um pincel, e em seguida, o restante do preparo é preenchido. Após finalizado o corpo do casquete, a área de retenção é criada (chapéu do casquete), a face vestibular é demarcada, e realizado acabamento e polimento.The aim of this manuscript was to describe the technique for manufacturing an individual impression cap for tooth preparation impression on the processing of full-contour prosthetic restorations, besides discussing factors and principles involved on this topic. In the present technique, first, a stone partial model is obtained, considering the region to be restored, and then a wax relief is created on its axial region to grant space for the impression material. After applying a resin isolator, the impression cap is obtained by incremental technique using a brush with chemically activated acrylic resin. Finally, a retention portion is created on the top of the obtained cap, the vestibular face is marked and then finishing and polishing are executed

Possibilidades restaurativas usando cerâmica de zircônia para coroas unitárias.

Two clinical cases are presented to explore technical differences and discusses the advantages and disadvantages of using veneered or monolithic zirconia to manufacture posterior single crowns. The first case describes the clinical steps in manufacturing a monolithic crown on a mandibular left second premolar using high translucency zirconia. It shows the use of a conservative tooth preparation based on the superior mechanical properties that this material presents as well as the final optical characteristics achieved by shading and staining. In the second case, a conventional bilayer restorative treatment was made using zirconia framework followed by veneering with feldspar ceramic on a mandibular left first molar. Recent literature indicates that each of these restorative alternatives presents specific advantages and disadvantages. Factors such as mechanical performance, fracture, esthetic characteristics, clinical success, complication rates, adhesion and antagonist wear performance are discussed comparing the two restorative assemblies. The data highlight that monolithic crowns prevent a major problem reported on bilayer restorations: the chipping of veneering ceramic. Monolithic crowns also allow minimally invasive tooth preparations, thus increasing tooth remnant preservation. However, data that support esthetic performance similarity between monolithic and bilayer assemblies are lacking, thus the predictability of use is restricted for the posterior region, as cases demanding high esthetic appeal continue to fundamentally use bilayer restorations. Failures were not found, and patient satisfaction was reported in both techniques after the 12-month follow up.Dois casos clínicos são apresentados para explorar as diferenças técnicas e discutir as vantagens e desvantagens do uso de zircônia folheada ou monolítica para confeccionar coroas únicas posteriores. O primeiro caso descreve as etapas clínicas na fabricação de uma coroa monolítica em um segundo pré-molar inferior esquerdo usando zircônia de alta translucidez. Mostra a utilização de um preparo dentário conservador baseado nas propriedades mecânicas superiores que este material apresenta, bem como nas características ópticas finais alcançadas pelo sombreamento e coloração. No segundo caso, foi realizado um tratamento restaurador convencional em bicamada com estrutura de zircônia seguida de estratificação com cerâmica de feldspato no primeiro molar inferior esquerdo. A literatura recente indica que cada uma dessas alternativas restauradoras apresenta vantagens e desvantagens específicas. Fatores como desempenho mecânico, fratura, características estéticas, sucesso clínico, taxas de complicações, desempenho de adesão e desgaste do antagonista são discutidos comparando os dois conjuntos restauradores. Os dados destacam que as coroas monolíticas evitam um grande problema relatado nas restaurações de duas camadas: o lascamento da cerâmica de recobrimento. As coroas monolíticas também permitem preparações dentárias minimamente invasivas, aumentando assim a preservação do remanescente dentário. No entanto, faltam dados que sustentem a similaridade do desempenho estético entre as montagens monolítica e bicamada, sendo a previsibilidade de uso restrita para a região posterior, pois casos que demandam alto apelo estético continuam a utilizar fundamentalmente as restaurações bicamada. Não foram encontradas falhas, e a satisfação do paciente foi relatada em ambas as técnicas após o acompanhamento de 12 meses

Advancements in Dental Care: The Evolving Landscape of Prosthetic Dentistry

In the dental field, the specialty of prosthodontics stands out as the frontline of innovation, continually pushing the boundaries to enhance both function and aesthetics for optimal oral rehabilitation [...

Effect of grinding and heat treatment on the mechanical behavior of zirconia ceramic

Abstract The present study investigated the effect of grinding on roughness, flexural strength, and reliability of a zirconia ceramic before and after heat treatment. Seven groups were tested (n = 15): a control group (labeled CG, untreated), and six groups of samples ground with diamond discs, simulating diamond burs, with grits of 200 µm (G80); 160 µm (G120), and 25 µm (G600), either untreated or heat-treated at 1200°C for 2 h (labeled A). Yttria tetragonal zirconia polycrystal discs were manufactured, ground, and submitted to roughness and crystalline phase analyses before the biaxial flexural strength test. There was no correlation between roughness (Ra and Rz) and flexural strength. The reliability of the materials was not affected by grinding or heat treatment, but the characteristic strength was higher after abrasion with diamond discs, irrespective of grit size. The X-ray diffraction data showed that grinding leads to a higher monoclinic (m) phase content, whereas heat treatment produces reverse transformation, leading to a fraction of m-phase in ground samples similar to that observed in the control group. However, after heat treatment, only the G80A samples presented strength similar to that of the control group, while the other groups showed higher strength values. When zirconia pieces must be adjusted for clinical use, a smoother surface can be obtained by employing finer-grit diamond burs. Moreover, when the amount of monoclinic phase is related to the degradation of zirconia, the laboratory heat treatment of ground pieces is indicated for the reverse transformation of zirconia crystals