The bond strength between veneering ceramic and zirconia framework is the weakest link in the layered structure. To investigate the shear bond strength (SBS) of veneering ceramics to zirconia, four types of zirconia ceramics (Zirkonzahn, Cercon, Lava, DC-Zirkon) were selected. For each zirconia system, 30 disk specimens were layered with IPS e.max Ceram, Vita VM9, and a manufacturer-recommended veneering ceramic. SBS test was conducted, and fracture surface analysis was also performed to determine the failure modes. One-way ANOVA, two-way ANOVA, and Tukey's HSD tests were used to analyze the data. On shear bond strength between zirconia and their recommended veneering ceramics, statistically significant differences were observed among the different zirconia systems (p 0.05). In conclusion, the bonding of manufacturer-recommended veneering ceramic to the zirconia framework differed according to zirconia type.

In vitro evaluation of shear bond strength of veneering ceramics to zirconia

Versch. in: Journal of Oral Rehabilitation 2003 30; 265–269 Ceramic-fused-to-metal restorations are widely used in dentistry with a high degree of general success. Fracture of the ceramic eneers as a result of oral function or trauma is not an uncommon problem in clinical practice. Although fractures of such restorations do not necessarily mean the failure of the restoration, the renewal process is both costly and time consuming and therefore remains a clinical problem. Fractures in the anterior region pose an aesthetic problem but when they are in the posterior, chewing function could also be affected. The published literature reveals that reasons for failures cover a wide spectrum from iatrogenic factors to laboratory mistakes or because of factors related to the inherent structure of the ceramics or simply to trauma.

Fracture reasons in ceramic-fused-to-metal restorations (Review)

Statement of problem Limited information is available regarding the metal-ceramic bond strength of dental Co-Cr alloys fabricated by casting (CAST), computer numerical control (CNC) milling, and selective laser melting (SLM). Purpose The purpose of this in vitro study was to evaluate the metal-ceramic bond characteristics of 3 dental Co-Cr alloys fabricated by casting, computer numerical control milling, and selective laser melting techniques using the 3-point bend test (International Organization for Standardization [ISO] standard 9693). Material and methods Forty-five specimens (25×3×0.5 mm) made of dental Co-Cr alloys were prepared by CAST, CNC milling, and SLM techniques. The morphology of the oxidation surface of metal specimens was evaluated by scanning electron microscopy (SEM). After porcelain application, the interfacial characterization was evaluated by SEM equipped with energy-dispersive spectrometry (EDS) analysis, and the metal-ceramic bond strength was assessed with the 3-point bend test. Failure type and elemental composition on the debonding interface were assessed by SEM/EDS. The bond strength was statistically analyzed by 1-way ANOVA and Tukey honest significant difference test (α=.05). Results The oxidation surfaces of the CAST, CNC, and SLM groups were different. They were porous in the CAST group but compact and irregular in the CNC and SLM groups. The metal-ceramic interfaces of the SLM and CNC groups showed excellent combination compared with those of the CAST group. The bond strength was 37.7 ±6.5 MPa for CAST, 43.3 ±9.2 MPa for CNC, and 46.8 ±5.1 MPa for the SLM group. Statistically significant differences were found among the 3 groups tested ( P =.028). The debonding surfaces of all specimens exhibited cohesive failure mode. Conclusions The oxidation surface morphologies and thicknesses of dental Co-Cr alloys are dependent on the different fabrication techniques used. The bond strength of all 3 groups exceed the minimum acceptable value of 25 MPa recommended by ISO 9693; hence, dental Co-Cr alloy fabricated with the SLM techniques could be a promising alternative for metal ceramic restorations.

Evaluation of metal-ceramic bond characteristics of three dental Co-Cr alloys prepared with different fabrication techniques.

Statement of problem New technologies have led to the introduction of new materials, so an evaluation of the adhesion of ceramics to these materials is needed. Purpose The purpose of this study was to compare the shear bond strength of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys, and to investigate the adhesive bond and failure type after thermocycling, 90 metal cylinders (10 mm diameter and 10 mm height) were prepared from cast (30 specimens), milled (30 specimens), and laser-sintered (30 specimens) alloys. Material and methods Ceramic cylinders (2.5 mm diameter and 4 mm length) were fused to the alloy cylinders. For each group, 15 specimens were thermocycled 5500 times at temperatures between 4°C and 60°C before testing. After testing, the specimen surfaces were visually examined to determine the failure mode. Differences in adhesion values according to manufacturing method, testing condition (thermocycling or no thermocycling), and interaction between the factors were evaluated with a 2-way ANOVA. The χ 2 test (95% confidence level) was performed to determine whether the failure mode was associated with the testing condition. Results Adhesion strengths for the nonthermocycled specimens were 42.79 ±14.14 MPa (cast), 37.56 ±9.18 MPa (milled), and 29.09 ±6.95 MPa (laser-sintered), and, for the thermocycled specimens, 16.52 ±8.96 MPa (cast), 22.21 ±13.25 MPa (milled), and 24.28 ±10.13 MPa (laser-sintered). Two-way ANOVA results indicated no statistically significant differences in adhesion among the manufacturing methods ( P =.257), but statistically significant differences were observed according to both testing conditions ( P P =.015). The χ 2 test indicated that the failure mode was not associated with the testing condition (thermocycled, P =.280; nonthermocycled, P =.240). Conclusions The porcelain adhesion values for all the materials were adequate for clinical applications. No significant adhesion differences were observed between cast, milled, and laser-sintered specimens, or among thermocycled and nonthermocycled laser-sintered specimens. However, significant adhesion differences were observed among the thermocycled and nonthermocycled cast and the milled specimens.

Adhesion of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys: shear bond strength and sensitivity to thermocycling.

Statement of problem Cobalt-chromium (Co-Cr) alloys have been widely used for metal-ceramic fixed prostheses and can be fabricated using conventionally cast or new computer-aided technology. However, the effect of different manufacturing methods on the metal-ceramic bond strength needs further evaluation. Purpose The purpose of this in vitro study was to evaluate the metal-ceramic bond strength of a Co-Cr alloy made by casting, milling, and selective laser melting (SLM). Material and methods Co-Cr specimens (25×3×0.5 mm) were prepared using a cast, milled, or SLM method and layered with ceramic (8×3×1.1 mm). Metal-ceramic bond strength was measured by a 3-point bend test according to ISO9693. The area fraction of adherence porcelain (AFAP) was determined by measuring the Si content of the specimens with scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The metal-ceramic bond strength and AFAP results were analyzed using 1-way analysis of variance and the Bonferroni post hoc test (α=.05). SEM/EDS and metallurgic microscopy were also used to study the specimens' morphology, elemental composition, and metallurgic structure. Results No significant differences ( P >.05) were found for the bond strength among cast, milled, and SLM Co-Cr alloys. The milled and SLM groups showed significantly more porcelain adherence than the cast group ( P Conclusions The bond strength between ceramics and Co-Cr alloys is independent of the manufacturing method. However, milling- and SLM-produced alloys had better porcelain adherence.

Bond strengths of porcelain to cobalt-chromium alloys made by casting, milling, and selective laser melting

Univ Estadual Paulista, Fac Odontol Sao Jose Dos Campos, Dept Dent Mat & Prosthodont, Sao Jose Dos Campos Dent Sch, BR-12250000 Sao Paulo, Brazil

Shear bond strength of a ceramic to Co-Cr alloys

O objetivo deste trabalho foi avaliar a resistencia da uniao ao cisalhamento entre uma liga de cobalto-cromo para metalo-cerâmica e uma cerâmica, utilizando diferentes agentes de uniao. A partir de um dispositivo metalico cilindrico, com 4mm de diâmetro e 5mm de altura, foram obtidos trinta padroes em cera e posteriormente fundidos em liga de Co-Cr (New Ceram, CNG). Os corpos-de-prova (cp) foram separados em tres grupos de acordo com o agente de uniao: G1: Controle – superficie jateada com oxido de aluminio (110μm); G2: Wash Opaque Vita Omega 900 (Vita) e G3: Pre Bond Opaque (CNG). Foi utilizado um dispositivo de teflon para compactar a cerâmica, e todos cp receberam aplicacao de revestimento estetico (Vita Omega 900), com 4mm de diâmetro por 4mm de altura. O ensaio mecânico de cisalhamento foi realizado numa maquina EMIC, a 0,5mm/min. As medias de resistencia de uniao para os grupos foram: G1-76,33±5,69MPa, G2-101,13±16,74 MPa e G3-114,55±6,80MPa. Os valores foram submetidos a analise de variância e ao teste de Tukey para comparacao entre os grupos (α = 0,05). Nao houve diferenca estatisticamente significativa entre os grupos tratados, contudo estes apresentaram valores superiores ao grupo controle. Pode-se concluir que os dois agentes de uniao determinaram valores semelhantes de resistencia de uniao entre metal e cerâmica, os quais foram superiores ao grupo controle.

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Avaliação da resistência da união metal-cerâmica utilizando diferentes agentes de união

Introduction: Rett syndrome is a neurodegenerative disease that affects females of all races worldwide. It is the second most frequent cause of mental disability in girls. Objective: To describe the general and oral characteristics at stage three. Case report: A girl aged seven years and seven months, leukoderma, coming from Vallo della Lucania, Salerno, Italy was at the stage three of Rett syndrome. At the first stage, from six to eighteen months of life, the girl ate by herself, but she did not walk. At the second stage, from eighteen months of life, she started the ataxic gait and stopped talking. At the third stage, she had the reduction of the autist behavior, improved the eye contact, smile and communicative abilities. The genetic examination revealed de novo mutation, that is, without inheritance. Conclusion: Rett syndrome lacks specific treatment. Adjuvant therapies include physiotherapy, hydrotherapy, occupational therapy, music therapy, equine therapy, as well as therapies to treat some symptoms. A multidisciplinary treatment is required. The prognosis consists of following-up the individual throughout life, treating the symptoms. Keywords: Autistic Disorder, Chronic disease, Epilepsy, Intellectual Disability, Rett Syndrome.

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General and oral characteristics of Rett syndrome: case report

Avaliação da resistência da união metal-cerâmica utilizando diferentes agentes de união Evaluation of metalceramic bond strength using different bonding agents

Objetivo: verificar a presenca de sinais e sintomas de DTM em individuos em tratamento ortodontico. Material e Metodos: foram avaliados 28 individuos que estavam em tratamento ortodontico na clinica de uma faculdade do estado de Sao Paulo. Para identificar a presenca de DTM foi utilizado o Research Diagnostic Criteria for Temporomandibular Disorders (RDC-TMD). A dor foi avaliada pela Escala Visual Analogica (EVA). A amplitude, dor e ruido durante os movimentos mandibulares, alem da dor a palpacao de musculos intra e extra orais e cervicais foram aferidos pelo Indice Craniomandibular (ICM). O limiar de dor a pressao foi avaliado por meio de algometro. Os valores medios e desvio padrao foram obtidos e a analise foi expressa em porcentagem. Resultados: o RDC-TMD demonstrou que a maioria dos individuos nao apresentaram DTM, que 3,57% apresentaram osteoartrite, 10,71% artralgia, 3,57% deslocamento de disco sem reducao, 7% dor miofascial e 14,28% dor miofascial com limitacao de abertura; A EVA evidenciou dor media de 1,37 cm (DP=1,4). A media do ICM foi de 0,26 (DP=0,14). O limiar de dor a pressao aferido com algometro foi de 3,7 (DP=1,7) para o m. temporal anterior e de 3,00 (DP=1,2) para o feixe superficial do m. masseter inferior. Conclusao : foram observados sinais e sintomas de DTM em 39,13% dos individuos em tratamento ortodontico.

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Renato Morales Jóias

Papers

Shear bond strength of a ceramic to Co-Cr alloys

Avaliação da resistência da união metal-cerâmica utilizando diferentes agentes de união

General and oral characteristics of Rett syndrome: case report

Avaliação da resistência da união metal-cerâmica utilizando diferentes agentes de união Evaluation of metalceramic bond strength using different bonding agents

Evaluation of TMD signals and symptoms in individuals undergoing orthodontic treatment