Zircônia na odontologia: mini-revisão / Zirconia in Dentistry: mini-review

Objetivo: O objetivo deste estudo é fornecer ao cirurgião-dentista conhecimento sobre aspectos gerais da zircônia e abordar a introdução das diferentes gerações. Materiais e métodos: Foi realizada uma pesquisa eletrônica da literatura atual em inglês, incluindo artigos científicos publicados até 2019. Resultados: De acordo com os artigos selecionados, diferenças importantes foram encontradas em relação as novas composições da zircônia, sua microestrutura, diferenças no conteúdo da fase cúbica, e de ítria na fase tetragonal, levando a diferentes propriedades ópticas, mecânicas e de resistência ao envelhecimento. Conclusão: A zircônia é o material mais resistente disponível entre as cerâmicas, com diferenças mecânicas e ópticas entre os materiais disponíveis. A introdução das coroas monolíticas resolveu o problema de lascamento da porcelana de cobertura, mas foram necessárias modificações estruturais para fornecer adequada translucidez.

Purpose: This study aims to provide knowledge to clinicians about general aspects of zirconia and to approach the introduction of different zirconia generations. Methods:An electronic search of the English current literature was conducted including scientific articles published up to 2019. Results: According to the selected articles, important differences were found in terms of the novel compositions of zirconia, microstructures among the materials, differences in cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. Conclusion: Zirconia is the most resistant material available among ceramics with mechanical and optical differences on available materials. The introduction of the monolithic crowns solving the veneering delamination but struc-tural modifications were necessary to provide adequate translucency

A randomized clinical trial of cavity liners after selective caries removal: one-year follow-up

Abstract Alternatives for the treatment of caries disease, such as minimally invasive approaches, have been developed in recent years. Objective: To carry out clinical and radiographic evaluations of three cavity liners after selective caries removal. Methodology: Thirty-six primary molars with deep occlusal caries lesions without pulp involvement (from children of both genders, aged between 5 and 8 years) were randomly divided into the following groups: calcium hydroxide cement (CHC) group; mineral trioxide aggregate (MTA) group and Portland cement with added zirconium oxide (PCZ) group. The following-up period was 6- and 12-month. The clinical and radiographic success rates were evaluated through chi-square test. The radiographic measurements were compared by ANOVA followed by Tukey's test (p<0.05). Results: Thirty-six patients were included, but thirty-four returned for 12-month follow-up. The overall success rate of the therapy for the three groups was 94.11% and no statistically significant differences occurred in the comparison among groups (p>0.05). Nineteen radiographs were selected to measure the dentin barrier thickness. The intragroup comparison presented a statistically significant increase of the dentin barrier for all groups, at 12-month follow-up. However, the MTA group showed increase of the dentin barrier, over time, 6- to 12-month follow-up. The intergroup comparison revealed no statistically significant differences (p>0.05). Conclusion: The clinical and radiographic data showed that all cavity liners provided effective treatment of primary teeth after selective caries removal.

Chemical and Microscopy Characterization of Trans-Endodontic Implants / Caracterización química y microscópica de implantes trans-endodónticos

Abstract Trans-endodontic implants are an artificial extension through root apex anchored in periradicular bone tissue. The aim is to improve the crown-root ratio and to provide stability to dental organ present. Zirconium oxide (ZrO2) is a material of great technological importance, having good natural color, high strength, high toughness, high chemical stability, does not suffer any corrosion, chemical and microbial resistance and excellent esthetic properties. Objective: The aim of this study was to evaluate chemical and microscopy of surface conditions of ZrO2 trans-endodontic implant. Materials and Methods: A blocks of ZrO2 were manufactured for produce trans-endodontic implants and divided in two groups: monoclinic and tetragonal phase. They were evaluated using Scanning Electroning Microscope (SEM), EnergyDispersive X-ray Spectroscopy (EDS), and Atomic Force Microscope (AFM) and Vickers Micro hardness. Results: The Monoclinic phase through AFM analysis showed roughness Ra = 0.320μm, whereas in the Tetragonal phase was 0.126μm, SEM/EDX indicated that the phases are not properly uniform and the addition of the Yttrium to favor the stabilization of the Tetragonal phase. The Vickers hardness analysis showed a value of 1500HV. Conclusion: The characterization of the surface of trans-endodontic zirconium oxide implants provides a guideline to know the surface characteristics of the material, since a greater roughness on the surface of the implant will favor the Osseo-integration capacity.

Resumen Los implantes trans-endodónticos son una extensión artificial a través del ápice radicular anclado en el tejido óseo periradicular. El objetivo es mejorar la relación corona-raíz y proporcionar estabilidad al órgano dental presente. El óxido de zirconio (ZrO2) es un material de gran importancia tecnológica, con buen color natural, alta resistencia, alta tenacidad, alta estabilidad química, no sufre corrosión, resistencia química y microbiana y excelentes propiedades estéticas. Objetivo: El objetivo de este estudio fue evaluar las condiciones superficiales de ZrO2 para su aplicación clínica a los implantes transendodónticos. Materiales y Métodos: se trituraron bloques de ZrO2 en implantes trans-endodónticos y se dividieron en: monoclínico y tetragonal. Luego se evaluaron mediante microscopía electrónica de barrido (SEM), espectroscopia de rayos X de energía dispersiva (EDS) y microscopio de fuerza atómica (AFM) y microdureza vickers. Resultados: La fase monoclínica a través del análisis AFM presenta Ra = 0.320 μm, mientras que en la fase Tetragonal es 0.126 μm, SEM / EDS muestra que las fases no son adecuadamente uniformes y la adición del Ytrio para favorecer la estabilización de la fase tetragonal. El análisis de microdureza mostro un valor de 1500HV. Conclusión: La caracterización de la superficie de los implantes trans-endodónticos de óxido de zirconio, brinda una pauta para conocer las características superficiales del material, ya que al haber una mayor rugosidad en la superficie del implante se verá favorecida la capacidad de oseointegración.

Durasphere® EXP: a non-biodegradable agent for treatment of primary Vesico-Ureteral reflux in children

ABSTRACT Introduction: Durasphere® EXP (DEXP) is a compound of biocompatible and non--biodegradable particles of zirconium oxide covered with pyrolytic carbon. The aim of this study is to evaluate the durability of off-label use of DEXP in the treatment of primary vesicoureteral reflux in children. Materials and Methods: Patients who underwent subureteric injection of DEXP for the correction of primary VUR were retrospectively reviewed. Patients aged >18 years as well as those who had grade-I or -V VUR, anatomic abnormalities (duplicated system, hutch diverticulum), neurogenic bladder or treatment refractory voiding dysfunction were excluded. Radiologic success was defined as the resolution of VUR at the 3rd month control. Success was radiographically evaluated at the end of the first year. Results: Thirty-eight patients (9 boys, 29 girls; mean age, 6.3±2.7 years) formed the study cohort. Forty-six renal units received DEXP (grade II: 22; grade III: 18; grade IV: 6). Mean volume per ureteric orifice to obtain the mound was 0.70±0.16mL. First con- trol VCUG was done after 3 months in all patients. After the first VCUG, 6 patients had VUR recurrence. Short-term radiologic success of DEXP was 84.2%. Rate of radiologic success at the end of the first year was 69.4% (25/32). Lower age (p:0.006) and lower amount of injected material (p:0.05) were associated with higher success rates at the end of 1 year. Conclusion: This is the first study to assess the outcomes of DEXP for treatment of primary VUR in children. After 1 year of follow-up, DEXP had a 69.4% success rate.

Implantes cerâmicos - evidências científicas para o seu uso / Ceramic implants - scientific evidence for its use

A cerâmica de zircônia (ZrO) vem sendo objeto de muitas pesquisas biomédicas pela excelente biocompatibilidade e estabilidade química. Nos últimos anos tem sido utilizada como uma opção aos implantes dentários metálicos, principalmente pelas qualidades estéticas e periointegração. O propósito desta revisão bibliográfica é destacar as características das cerâmicas Y-TZP (zircônia tetragonal policristalina estabilizada com ítria) e ATZ (zircônia tenacificada por alumina), citando algumas limitações do uso como materiais alternativos na Implantodontia, baseadas em evidências científicas. Muitas pesquisas in vitro e in vivo demonstraram que as cerâmicas Y-TZP apresentam vantagens estéticas e biológicas sobre outros biomateriais. Os valores de resistência à fratura são clinicamente aceitáveis, sendo mais elevados nos compósitos ATZ. Alguns testes de carga cíclica com implantes dentários ATZ mostraram resistência igual ou superior aos de titânio (Ti). Novos tratamentos de superfície na cerâmica estão abreviando o tempo de cura, possibilitando carga imediata. Os experimentos com animais confirmaram o bom potencial de osseointegração das cerâmicas, com quantidade de BIC equiparável ao Ti e com menor acúmulo de biofilme. Estudos de até 5 anos com implantes dentários Y-TZP de peça única em humanos apresentaram índices de sucesso de 84,4 a 100%, enquanto que a taxa de sobrevida em 7 anos com ATZ foi de 99%. Apesar dos bons resultados com implantes dentários Y-TZP e ATZ, os autores sugerem cautela nas indicações e mais estudos prospectivos de longo prazo.

Ceramic zirconia (Zr02) has been the subject of many biomedical researches due to its excellent biocompatibility and chemical stability. In recent years it has been used as an alternative to metallic dental implants, and mainly for its aesthetic periointegration qualities. The purpose of this literature review was to evaluate some of the characteristics of ceramic Y-TZP (tetragonal zirconia polycrystalline yttria stabilized) and ATZ (zirconia toughened alumina), pointing its limitations of use as alternative materials in Implantology. Many in vitro and in vivo studies have demonstrated that the ceramics Y-TZP exhibit aesthetic and biological advantages over other biomaterials. The values of fracture toughness are clinically acceptable, being higher in ATZ composites. Some cyclic loading tests with ATZ dental implants showed resistance equal or superior to titanium (Ti). New surface treatments for ceramics have shortened the cure time, allowing immediate loading. Animal experiments have confirmed the good potential for osseointegration of ceramic, with the amount of BIC comparable to Ti and less accumulation of biofilm. Studies up to 5 years with dental implants Y-TZP one-piece in humans have success rates between 84.4 and 100%, whereas the survival rate in 7 years with ATZ implants was 99%. Despite the good results with the ceramic Y-TZP and ATZ, the authors suggest caution in their indications and further long-term prospective studies are required.

Study on nano-structured hydroxyapatite/zirconia stabilized yttria on healing of articular cartilage defect in rabbit

PURPOSE: Articular Cartilage has limited potential for self-repair and tissue engineering approaches attempt to repair articular cartilage by scaffolds. We hypothesized that the combined hydroxyapatite and zirconia stabilized yttria would enhance the quality of cartilage healing. METHODS: In ten New Zealand white rabbits bilateral full-thickness osteochondral defect, 4 mm in diameter and 3 mm depth, was created on the articular cartilage of the patellar groove of the distal femur. In group I the scaffold was implanted into the right stifle and the same defect was created in the left stifle without any transplant (group II). Specimens were harvested at 12 weeks after implantation, examined histologically for morphologic features, and stained immunohistochemically for type-II collagen. RESULTS: In group I the defect was filled with a white translucent cartilage tissue In contrast, the defects in the group II remained almost empty. In the group I, the defects were mostly filled with hyaline-like cartilage evidenced but defects in group II were filled with fibrous tissue with surface irregularities. Positive immunohistochemical staining of type-II collagen was observed in group I and it was absent in the control group. CONCLUSION: The hydroxyapatite/yttria stabilized zirconia scaffold would be an effective scaffold for cartilage tissue engineering.

Implantes de zircônia reforçada com ítria (Y-TZP): avaliação histomorfométrica / Y-TZP dental implants: histomorfometry analysis

O objetivo do trabalho foi avaliar in vivo a osseointegração de implantes produzidos em zircônia reforçada com ítria (Y-TZP) e compará-los com o implante de titânio usinado e com o de superfície jateada com brushita. Para tanto, nas tíbias de 20 coelhos machos (n=10) e fêmeas (n=10) foram implantadas em uma das tíbias o implante Y-TZP (GE-1, n=10 implantes) e na outra tíbia o titânio usinado (GC, n=5 implantes) ou jateado com brushita (GE-2, n=5 implantes). Os animais receberam marcadores ósseos fluorescentes, tetraciclina (14 e 21 dias), alizarina (28 e 35 dias) e calceína (42 e 49 dias) após a cirurgia de implantação. Ao final de 56 dias, a região dos implantes foi coletada e processada histologicamente para obtenção de cortes teciduais não desmineralizados. Nas imagens obtidas no microscópio confocal foi avaliado o percentual de área para cada marcador. Nos cortes corados pelo azul de toluidina foi avaliado morfologicamente a qualidade do tecido ósseo formado e a existência de interposição de tecido conjuntivo entre osso e implante, e morfometricamente determinado o percentual de contato osso-implante (BIC) e o percentual de tecido ósseo próximo à superfície do implante (BA). Os resultados mostraram que, não houve diferenças estatisticamente significantes entre machos e fêmeas quanto aos parâmetros avaliados. Com relação aos grupos, GE-1 e GC apresentaram cortical óssea remanescente íntegra e formação de um tecido ósseo maduro/lamelar na superfície dos implantes. No GE-2 ocorreu intensa reabsorção da cortical óssea pre-existente próxima ao implante e extensa formação óssea mais imatura em relação aos observados no GE-1 e GC. Essa intensa reabsorção e extensa formação óssea fez com que o percentual de área dos marcadores fluorescentes fosse em média 0,73 vezes maior no GE-2 em relação aos grupos GE-1 e GC. Com relação ao BIC não houve diferença entre os grupos, sendo em média de 47,8%, porém, o BA no grupo GC (66,2%) foi 0,33 vezes...

The aim of this work was evaluate in vivo the osseointegration of implants produced with yttria stabilized zirconia (Y-TZP) and compare it with machined titanium implant and sandblasted surface with brushita titanium. Therefore, on the tibia of 20 rabbits males (n=10) and female (n=10) were implanted in one of the tibias the implant Y-TZP (GE-1, n=10 implants) and on the other tibia the machined titanium (GC, n=5 implants) or sandblasted surface with brushita titanium (GE-2, n=5 implants). The animals received fluorescent bone markers, tetracycline (14th and 21th days), alizarin (28th and 35th days) and calcein (42th and 49th days). At the end of 56 days, the implants regions were collected and histomorphometrically processed to obtain tissue sections not demineralized. On images obtained from confocal microscopy was evaluated the percentage of area for each bone markers. On slides stained with toluidine blue was measured morphologically the quality of formed bone tissue and the existence of interposition of connective tissue between bone and implant, and was morphometrically determined the percentage of bone-implant contact (BIC) and the percentage of bone tissue next to the implant surface (BA). The results showed that there were no statistically significant differences between male and female regarding to evaluated parameters. Concerning to the groups, GE-1 and GC exhibited wholesome remaining cortical bone and formation of mature/lamellar bone tissue on implants surface. In GE-2 ocurred intense reabsorption of preexisting cortical bone next to the implant and extensive bone formation more immature than GE-1 and GC. This intense reabsorption and extensive bone formation made the GE-2 area percentage for fluorescent markers 0.73 times higher on average when compared to GE-1 and GC. About the BIC, there were no differences between the groups, with an average of 47.8%, however, the BA on GC group (66.2%) was 0.33 higher compared to GE-1...

A systematic review of zirconia as an implant material.

The purpose of this systematic review was to assess the published data concerning zirconia dental implants from various aspects. To identify relevant literature an electronic search was performed of PubMed. Titles and abstracts were screened and articles that fulfilled the inclusion criteria were selected for a full-text reading. Articles were divided into four groups: 1) studies evaluating the mechanical properties of zirconia implants, 2) studies on osseointegration of zirconia, 3) studies on peri-implant tissue response to zirconia implant, and 4) studies on plaque accumulation with zirconia. Review of the selected articles showed that zirconia implants are reliable for placement in the jaw bone. Furthermore, zirconia implants present a material surface that is compatible with the peri-implant tissue and relatively less attractive to plaque. Based on the reviewed literature, it appears that zirconia has the potential to become the dental implant material of choice, especially for aesthetic restorations; however, some issues need to be studied further.

Cimentação adesiva de cerâmicas à base de zircônia / Adhesive cimentation of circonia ceramics

As cerâmicas de alto conteúdo cristalino, como a zircônia, apresentam ótimas propriedades mecânicas quando comparadas às cerâmicas convencionais, sendo cada vez mais empregadas como materiais restuaradores indiretos. Entretanto, seu sucesso também depende da formação de uma união confiável com os agentes de cimentação. O aumento do conteúdo cristalino modificou as características de adesão entre cerâmica e cimento resinoso, não existindo um protocolo de cimentação bem estabelecido na literatura...

Zirconium for esthetic rehabilitation: An overview.

The demand for esthetic restorations has resulted in an increased use of dental ceramics for anterior and posterior restorations. A few decades ago, all-ceramic restorations were restricted to treatment in the anterior region, but now all-ceramic restorations can be made anywhere in the dentition. The properties of traditional ceramic materials, however, have limited their use to single crowns; larger restorations have been inadvisable because of insufficient strength. In attempts to meet the requirements for dental materials and improve strength and toughness, several new ceramic materials and techniques have been developed during the past few decades The paper reviews the current literature on dental zirconia with respect to survival, properties, marginal fit, cementation, esthetics and suggests clinical recommendations for their use.

Adaptação marginal das cerãmicas à base de zircônia

O objetivo deste estudo é fazer, através de um levantamento bibliográfico, uma avaliação compartiva da adaptação marginal dos diferentes tipos de cerâmicas à base de zircônia...