Recycling CAD/CAM lithium disilicate ceramic: effect of surface treatment and aging on the bond strength to resin cement.

PURPOSE: To investigate the effect of recycling of lithium disilicate (LD), surface treatment and thermocycling (TC) on the bond strength (SBS) to resin cement. MATERIALS AND METHODS: Blocks of LD were made according to the recycling cycle, with 24 blocks for each strategy: Control-conventional sintering; 1R (1 recycling cycle) and 3R (3 recycling cycles). For the recycling groups, blocks were waxed (10x10x3mm), mounted in a silicone ring, poured with investment material, and then residues of sintered LD blocks were pressed by the lost wax technique. The residual LD was reused as described until reach 3R. Afterwards, the blocks were embedded in acrylic resin, sanded and divided (n=15) according to the factors "surface treatment" (HF20s+Silane and HF120s+Silane and Monobond Etch&Prime- MEP) and TC (with/10.000 cycles and without). After surface treatment, cylinders (Ø:2mm) of resin cement were made and submitted to SBS test (100KgF,1mm/min). Data (MPa) were analyzed by 3-way ANOVA, Tukey's test (5%) and Weibull analysis. Failure analysis was performed with stereomicroscope. RESULTS: ANOVA revealed that all factors were significant (P=.000*). The group 3RMEP(105.09±19.49) presented the highest SBS among the experimental groups. 1RHF20sTc(7.50±1.97) group had the lowest SBS, similar to the CHF20sTc(15.69±3.77), 1RHF20s(15.12±3.03), 1RHF120sTc(14.60±3.43) and 3RHF20sTc(15.65±0.97). The Weibull modulus and characteristic strength varied among the experimental groups (P=0.0). Failure analysis revealed adhesive and mixed types. CONCLUSION: The recycling of DL ceramics increases the SBS to resin cement when the ceramic is treated with HF120s+S or MEP.

Effect of dentifrices with different pH and fluoride concentrations on fluoride levels in biofilm and nails: an RCT.

PURPOSE: to evaluate the effect of dentifrice pH and fluoride concentration ([F]) on fluoride uptake on the biofilm and nails of children from a non-fluoridated area. METHODS: two hundred and twenty-eight two- to four-year-old children were randomly allocated into 3 groups according to the type of dentifrice: G1: 1100 µg F/g, pH 4.5 (n = 76); G2: 750 µg F/g, pH 4.5 (n = 74); and G3: 1100 µg F/g, pH 7.0 (n = 78). Nails were collected at 4, 8, and 12 months after starting dentifrice use and biofilm was collected 5 and 60 minutes after toothbrushing. The concentrations of F in nails and biofilm were analyzed by HMDS facilitated diffusion. Data were analyzed by Kruskal-Wallis/Mann-Whitney's test and the comparison between biofilm collection times was done using Wilcoxon test (p £ 0.05). RESULTS: a significant reduction of [F] in biofilm was observed 60 minutes after toothbrushing, regardless of the dentifrice used. However, 5 minutes after toothbrushing, G1 had a significantly higher [F] compared to G2 and G3, and 60 minutes after toothbrushing, [F] was significantly higher for G1 and G2 compared to G3. G1 and G3 had significantly higher [F] in the nails compared to G2. CONCLUSION: a lower dentifrice concentration is a relevant factor for the reduction of excessive fluoride intake. The use of a low-F acidified dentifrice combines the reduction of fluoride uptake with caries prevention by leading to greater incorporation of F into the biofilm over time.

Effect of dentifrices with different pH and fluoride concentrations on fluoride levels in biofilm and nails: an RCT

Abstract: Purpose: to evaluate the effect of dentifrice pH and fluoride concentration ([F]) on fluoride uptake on the biofilm and nails of children from a non-fluoridated area. Methods: two hundred and twenty-eight two- to four-year-old children were randomly allocated into 3 groups according to the type of dentifrice: G1: 1100 μg F/g, pH 4.5 (n = 76); G2: 750 μg F/g, pH 4.5 (n = 74); and G3: 1100 μg F/g, pH 7.0 (n = 78). Nails were collected at 4, 8, and 12 months after starting dentifrice use and biofilm was collected 5 and 60 minutes after toothbrushing. The concentrations of F in nails and biofilm were analyzed by HMDS facilitated diffusion. Data were analyzed by Kruskal-Wallis/Mann-Whitney's test and the comparison between biofilm collection times was done using Wilcoxon test (p £ 0.05). Results: a significant reduction of [F] in biofilm was observed 60 minutes after toothbrushing, regardless of the dentifrice used. However, 5 minutes after toothbrushing, G1 had a significantly higher [F] compared to G2 and G3, and 60 minutes after toothbrushing, [F] was significantly higher for G1 and G2 compared to G3. G1 and G3 had significantly higher [F] in the nails compared to G2. Conclusion: a lower dentifrice concentration is a relevant factor for the reduction of excessive fluoride intake. The use of a low-F acidified dentifrice combines the reduction of fluoride uptake with caries prevention by leading to greater incorporation of F into the biofilm over time.

Avaliação in vitro de propriedades mecânicas de resinas compostas com adição de zircônia e de resina composta com adição de zircônia e diatomita utilizadas em restaurações semidiretas / In vitro evaluation of mechanical properties of composite resins with the addition of zirconia and composite resin with the addition of zirconia and diatomite used in semi-direct restorations

INTRODUÇÃO: A incorporação de partículas de carga às resinas compostas tem o papel de melhorar suas propriedades físicas e mecânicas, conferindo uma maior resistência às restaurações. Muitos compósitos possuem nanopartículas incorporadas a sua composição, como quartzo, zircônia, sílica e, mais recentemente, a diatomita, que é uma rocha sedimentar rica em sílica. A adição dessas partículas busca aumentar a área de superfície e promover maior interação com a matriz orgânica. OBJETIVOS: Esse estudo objetivou avaliar resistência de união (RU), padrão de fratura (PF), profundidade de polimerização (PP), resistência a flexão (RF) e módulo de elasticidade (ME) de resinas compostas convencionais com adição de zircônia, com adição de zircônia e diatomita e de incremento único, em restaurações confeccionadas pela técnica semidireta, em dois tempos de envelhecimento (24h e 6 meses). METODOLOGIA: Foram criadas cavidades troncocônicas em dentina de incisivos bovinos (N=136), para confecção de restaurações semidiretas utilizando as resinas: Bulk Fill (BF) (3M ESPE®), Resina Z250 XT (Z250XT) (3M ESPE®), Resina Zirconfill (ZF) (BM4®) e Resina Z350 XT (Z350XT) (3M ESPE®), cimentadas com cimento resinoso dual autocondicionante RelyX Ultimate (3M ESPE®). As amostras foram armazenadas por 24 horas e 6 meses em estufa a 37ºC antes da realização dos testes de RU e PF, sendo as amostras com 24 horas selecionadas para o teste de PP. Para os testes de RF e ME, utilizando uma matriz de silicone, foram confeccionados palitos padronizados (10,0 mm. x 1,0 mm. de altura x 2,0 mm.) para cada resina testada (n=10) e também armazenados em estufa a 37ºC por 24h e 6 meses antes da realização dos testes. RESULTADOS: Na análise imediata, a resina ZF apresentou a maior RU entre os grupos e apresentou diferença estatisticamente significativa com o grupo BF. Já a resina Z350 aumentou sua RU com o tempo de envelhecimento. Não houve diferença entre a RF das resinas analisadas após 24h, porém após 6 meses a Z250 apresentou a menor média, enquanto os demais grupos aumentaram a RF com o tempo, sendo o maior aumento para o grupo da ZF. Com relação ao ME, apenas as resinas Z350 e ZF apresentaram diferença estatisticamente significativa com o tempo de envelhecimento das amostras, aumentando esse valor. As fraturas mistas foram predominantes para todos os compósitos em ambos os tempos de envelhecimento e para PP não foram encontradas diferenças estatisticamente significativas entre os grupos de estudo. CONCLUSAO: As resinas que continham adição de zircônia ou zircônia e diatomita no seu conteúdo inorgânico, bem como a resina de incremento único mostraram comportamentos positivos diante as propriedades de RU, a RF e o ME, principalmente para as resinas Z350XT e ZF. Estudos clínicos são recomendados para comprovar os resultados desse estudo laboratorial (AU).

INTRODUCTION: The incorporation of filler particles in composite resins has the role of improving their physical and mechanical properties, providing greater resistance to restorations. Many composites have nanoparticles incorporated into their composition, such as quartz, zirconia, silica and, more recently, diatomite, which is a silica-rich sedimentary rock. The addition of these particles seeks to increase the surface area and promote greater interaction with the organic matrix. OBJECTIVES: This study aimed to evaluate bond strength (RU), fracture pattern (PF), polymerization depth (PP), flexural strength (RF) and elasticity module (ME) of conventional composite resins with zirconia addition, with addition of zirconia and diatomite and single increment, in restorations made by the semi-direct technique, in two aging times (24h and 6 months). METHODOLOGY: Trunk-cone cavities were created in dentin of bovine incisors (N = 136), for the manufacture of semi-direct restorations using resins: Bulk Fill (BF) (3M ESPE®), Resin Z250 XT (Z250XT) (3M ESPE®), Resin Zirconfill (ZF) (BM4®) and Z350 XT Resin (Z350XT) (3M ESPE®), cemented with RelyX Ultimate self-etching dual resin cement (3M ESPE®). The samples were stored for 24 hours and 6 months in an oven at 37ºC before the RU and PF tests were carried out, and the samples with 24 hours were selected for the PP test. For the RF and ME tests, using a silicone matrix, standard toothpicks (10.0 mm. X 1.0 mm. High x 2.0 mm.) Were made for each tested resin (n = 10) and also stored in an oven at 37ºC for 24h and 6 months before testing. RESULTS: In the immediate analysis, the ZF resin showed the highest RU among the groups and showed a statistically significant difference with the BF group. The Z350 resin increased its RU with the aging time. There was no difference between the RF of the resins analyzed after 24 hours, but after 6 months the Z250 showed the lowest average, while the other groups increased the RF over time, with the greatest increase for the ZF group. Regarding ME, only resins Z350 and ZF showed a statistically significant difference with the aging time of the samples, increasing this value. Mixed fractures were predominant for all composites in both aging times and for PP, no statistically significant differences were found between the study groups. CONCLUSION: The resins that contained added zirconia or zirconia and diatomite in their inorganic content, as well as the single-increment resin showed positive behaviors in relation to the properties of RU, RF and ME, mainly for resins Z350XT and ZF. Clinical studies are recommended to confirm the results of this laboratory study (AU).

Violência contra crianças e adolescentes: conhecimentos dos odontopediatras da capital paraibana: estudo piloto / Violence against children and teens: knowledge of the dentists of the capital of Paraiba: pilot study

O Cirurgião-Dentista tem a obrigação ética e legal na identificação/notificação dos casos de maus-tratos. Objetivo: Objetivou-se com esse estudo analisar o conhecimento dos Odontopediatras da cidade de João Pessoa-PB sobre maus-tratos infantis. Tratou-se de um estudo quantitativo, exploratório, bibliográfico e descritivo. O universo dessa pesquisa compreendeu 44 Cirurgiões-Dentistas regularmente inscritos no Conselho Regional de Odontologia da Paraíba, com especialidade em Odontopediatria, em qualquer faixa etária de ambos os sexos. Para realização do cálculo amostral foi considerado grau de confiança de 95%, ficando uma amostra de 40 Odontopediatras. Métodos: Aplicou-se um questionário com 11 questões que atendiam aos objetivos da pesquisa. Os dados coletados foram tabulados em uma plataforma do Microsoft Excel e analisados mediante estatística descritiva (valores de frequência absoluta e percentual) no software IBM SPSS (21.0). Resultados: A maioria dos profissionais é do sexo feminino (93,5%) e 48,39% têm mais que a 4a década de vida. 51,61% definiram maus-tratos infantis de forma incompleta, 51,6% classificaram de forma completa, conforme a Associação Brasileira Multiprofissional de Proteção à Infância e à Adolescência; os sinais/sintomas bucais mais citados foram fraturas dentárias (41,07%), queimaduras (21,43%), lacerações (14,29%) e hemato¬mas (12,5%); já os sinais/sintomas corporais mais citados foram hematomas (35,6%), queimaduras (20,34%), fraturas (15,25%) e lacerações (10,17%). A maioria dos pesquisados relatou saber agir diante de casos de maus-tratos (93,5%), entre eles 76,92% denunciariam ao conselho tutelar e 54,8% demonstram interesse em capacitação. Conclusão: De forma geral, houve conhecimento parcialmente satisfatório dos Odontopediatras inscritos no CRO-PB sobre maus-tratos infantis.

The Dentist has ethical and legal obligation to identify/report cases of abuse. Objective: The objective of this study is to analyze the knowledge of dentists in the city of João Pessoa-PB-Brazil, on child abuse. The research carried out a quantitative, exploratory, bibliographic and descriptive study. The research universe comprises 44 pediatric dentists regularly registered in the Regional Council of Dentistry, specialized in pediatric dentistry in any age group of both genders. For performing the sample calculation was considered a confidence level of 95%, getting a sample of 40 dentists. Methods: They received a questionnaire with 11 questions that met the research objectives. The collected data were typed into a Microsoft Excel platform and analyzed using descriptive statistics (absolute and percentage frequency values) in IBM SPSS software (21.0). Results: Most professionals are female (93,5%), (48,39%) of these corresponded to more than four decades of life. 51.61% of the interviewed people defined child abuse incompletely, 51.6% rated child abuse completely, signs/symptoms most cited were oral dental fractures (41.07%), burns (21.43%), lacerations (14.29%) and he¬matomas (12.5%), the physical signs/symptoms most cited were hematomas (35.6%), burns (20.34%), fractures (15.25%) and lacerations (10.17%). 93.5% of respondents would know how to act on cases of child abuse, among them 76.92% would denounce the tutelary assistance and 54.8% have an interest in training. Conclusion: Overall, there was partially adequate knowledge of the registered dentists in the CRO-PB on child abuse.