Fatigue methods for evaluating translucent dental zirconia.

OBJECTIVE: To investigate fatigue methods for the evaluation of translucent zirconia and to associate in vitro failures with clinically reported ones. DATA: Studies published in English that used fatigue tests on dental translucent zirconia. SOURCES: Two databases (MEDLINE/PubMed and Scopus) were electronically searched without any restriction on year of publication. STUDY SELECTION: A total of 4555 studies were identified. After removal of duplicates (78) and irrelevant articles (4316) that did not meet the inclusion criteria, 161 articles were considered eligible based on their titles and abstracts. These articles were fully read, leading to the inclusion of 41 studies in the review. RESULTS: The most widely used fatigue method for evaluation of translucent zirconia was step-stress (18 articles), followed by staircase (seven articles), and step-wise (two articles). Most studies had been conducted in a wet environment with the use of a stainless steel piston to apply load to cemented structures on a dentin-like substrate. Most fracture analyses indicated the fracture originated on the cementation or contact surface where the load was applied. Moreover, studies that utilized anatomical structures (dental crowns) reported fractures starting at the cervical margin of the crowns. CONCLUSION: Most studies used the step-stress method. Only three studies reported failures similar to those found in clinical trials that used translucent zirconia restorations. CLINICAL SIGNIFICANCE: The study findings can assist on correlating clinical failures to the ones observed in vitro.

Longevity of different abutments placed on narrow diameter implants: Assessment of structural damage and loosening.

OBJECTIVES: To evaluate structural damage and loosening of abutments placed on narrow diameter implants after cyclic fatigue. METHODS: Sixty Morse taper narrow diameter implants (Neodent, Brazil) received two types of abutments (1PA- one-piece abutment or 2PA- two-piece abutment), which were randomly divided into 3 fatigue experiments (n = 10). The implants were placed into a customized supporting holder and a software-assisted digital torque wrench secured the manufacturer recommended torque for each abutment. Cone beam computed tomography (CBCT) scans were acquired, before and after fatigue, and post-processed (software e-Vol DX) to assess damage and abutment displacement. The boundary fatigue method was adapted to use 2 × 106 cycles, 2 Hz of frequency and constant peak load of 80 N (first experiment) that varied according to the failure rate of previous specimens (second and third experiments). Failure was evaluated using CBCT scans and removal torque values. Data were used to estimate long-term torque degradation, probability of failure and Weibull modulus (software ALTA PRO9). RESULTS: All 2PA specimens became loosen independently of the applied fatigue load, and structural bending was observed in 14 abutments. Eight 1PA got loosen during the fatigue experiment. The Weibull analysis showed a lower modulus (m = 1.0; 0.7, 1.4) for 1PA than for 2PA (m = 2.6; 2, 3.4) resulting in longer predicted lifetimes and slower torque degradation for 1PA than for 2PA specimens. SIGNIFICANCE: 1PA showed greater long-term survival probability than 2PA. Predicting the lifetime and mechanical behavior of implant-abutment systems are useful information to clinicians during the decision-making process of oral rehabilitations.

The influence of filler load in 3D printing resin-based composites.

OBJECTIVE: To evaluate the influence of the barium glass (BG) filler in 3D printing resin-based composites for restorative structures. METHODS: Experimental 3D printing resin-based composites were formulated with UDMA 70%wt, Bis-EMA 20%wt, and TEGDMA 10%wt. Photoinitiators TPO and DFI (2%wt) were used. BG was incorporated at 40%wt and 50%wt. 0%wt BG was used as negative control and the VarseoSmile Crownplus (Bego) was used as a commercial control. Specimens were printed using a 3D printer. Subsequently, specimens were washed and submitted to post-curing with 405 nm at 60ºC for 2 × 20 min at FormCure (FormLabs). 3D printing resin-based composites were evaluated by flexural strength, degree of conversion, softening in solvent, radiopacity, and cytotoxicity against gingival fibroblasts. Data were statistically analyzed using one-way ANOVA (α = 0.05). RESULTS: No significant differences in flexural strength were showed between BG40% (90.5 ± 5,4 MPa), BG50% (102.0 ± 11.7 MPa) and VA (105.2 ± 11.7 MPa). Addition of 40% and 50% of BG showed no influence in the degree of conversion compared to VA (p > 0.05). All groups showed softening in solvent after immersion in ethanol (p < 0.05). All groups showed more than 1mmAl of radiopacity. BG50% showed significantly higher radiopacity (2.8 ± 0.3 mmAl) than other groups (p < 0,05). Cytotoxicity evaluation showed gingival cell viability higher than 80% for all groups. SIGNIFICANCE: Addition of up to 50%wt of barium glass in experimental 3D printing resin-based composites showed promising results for long-term restorative structures.

Influence of printing orientation on mechanical properties of aged 3D-printed restorative resins.

OBJECTIVE: To evaluate the influence of printing orientation on flexural strength (σf) and elastic modulus (E) of different 3D printing dental restorative resins. METHODS: Bar-shaped specimens (n = 20) were fabricated from two SLA-printed resins (FT- Formlabs Temporary, and FP- Formlabs Permanent) and two DLP-printed resins (DFT- Detax Freeprint Temp, and GCT- GC Temporary) using two building orientations (0º and 90º). The 3D-printed structures were aged (14 d) before submitted to three-point bending in 37ºC distilled water at a crosshead speed of 1.0 ± 0.3 mm/min until fracture to calculate the σf and the E values. The fractured surfaces were evaluated using stereomicroscopy and scanning electron microscopy (SEM) following fractography principles. Data were statistically analyzed using two-way ANOVA and Tukey post-hoc (α = 0.001). RESULTS: FP and FT showed significantly higher E values than DFT and GCT, irrespectively of printing orientation (p < 0.001). There was no statistical difference between the building orientations (0º and 90º) for the mean σf and E values for the resin materials evaluated. Fractographic characteristics were similar for the surface fracture from all the materials evaluated, showing typical brittle fracture behavior. SIGNIFICANCE: Printing orientation did not influence of flexural strength and elastic modulus values for the 3D-printed resin structures evaluated. Surface topography was mostly governed by the 3D printer type.

Brazilian primary dental care in a universal health system: Challenges for training and practice.

OBJECTIVES: To report the challenges for training and practice for the Brazilian primary dental care in a universal health system. METHODS: Health, education and protection rights against poverty are guaranteed by the 1988 Brazilian Constitution and public health in Brazil is provided by the Unified Health System (SUS), one of the largest public health systems in the world. According to SUS, every Brazilian citizen has the right to free primary oral health care as secondary and tertiary care, offering a unique opportunity to integrate oral care within general health care. RESULTS: The Brazilian undergraduate Dental curriculum was updated in 2021 aiming to graduate general practitioners with a major in comprehensive health care in primary health care, integrated with public and general health. This curriculum update requires at least 20% of the academic hours to be exercised outside the university walls (extramural or community work), preferably within the SUS. CONCLUSIONS: Considering the World Health Organization (WHO) agenda, Brazil needs to advance the innovative oral health workforce, the integration of oral health into primary care, the population access to essential dental medicines and optimal fluorides for caries control. CLINICAL SIGNIFICANCE: It is necessary political action and the engagement of multiple stakeholders, mainly from the health and education sectors, to improve primary health care.

Biomechanical Behavior of a 3D-Printed Denture Base Material.

PURPOSE: To evaluate relevant material properties (flexural strength [σf], elastic modulus [E], water sorption [Wsp] and solubility [Wsl], and biocompatibility) of an additive manufacturing (AM) polymer vs a heat-curing acrylic resin (AR; control) for the manufacture of complete dentures, testing the hypothesis that fabrications from both materials would present acceptable material properties for clinical use. MATERIALS AND METHODS: The σf, E, Wsp, and Wsl were evaluated according to the ISO 20795-1:2013 standard, and the biocompatibility was evaluated using MTT and SRB assays. Disk-shaped specimens were fabricated and used for Wsp (n = 5), Wsl (n = 5), and biocompatibility (n = 3) testing. For assessment of σf and E, bar-shaped specimens (n = 30) were fabricated and stored in 37°C distilled water for 48 hours or 6 months before flexural testing in a universal testing machine with a constant displacement rate (5 ± 1 mm/minute). Data from σf, E, Wsp, Wsl, and biocompatibility tests were statistically analyzed using Student t test (α = .05). Weibull analysis was also used for σf and E data. RESULTS: Significant differences between the two materials were found for the evaluated material properties. Water storage for 6 months did not affect the flexural strength of the AM polymer, but this material showed inadequate σf and Wsl values. CONCLUSIONS: Despite adequate biocompatibility and strength stability after 6 months of water storage, the AM polymer recommended for complete dentures needs further development to improve the material properties evaluated in this study.

Structural and torque changes in implant components of different diameters subjected to mechanical fatigue.

OBJECTIVES: To evaluate torque maintenance and structural damage in implant components of different diameters subjected to a fatigue challenge. METHODS: Thirty 10-mm-long, morse taper connection, titanium dental implants and their corresponding one-piece abutments were divided into three groups (n = 10) according to implant diameter: 4.3 mm (I4.3), 3.5 mm (I3.5), and 2.9 mm (I2.9). The implants were placed into a load-bearing fixture simulating bone tissue (modified G10), and the abutments were screwed into the implants to a final torque of 20 Ncm for the I4.3 and I3.5 and 15 Ncm for I2.9. The torque was secured by a digital torque meter. Cone-beam computed tomography (CBCT) scans were acquired and post-processed (e-Vol DX software) for all implant/abutment sets before and after subjecting them to fatigue in 37 °C distilled water (2 million cycles, constant load and frequency). The removal torque was measured using the same digital torque meter to calculate the difference in torque before and after fatigue. RESULTS: I2.9 showed substantial structural deformation compared with the other implant diameters (I3.5 and I4.3). However, the experimental groups did not show statistical differences for abutment loosening. SIGNIFICANCE: Implants smaller than 3.5 mm in diameter have a higher probability of structural deformation than standard-diameter implants. The association between tomographic scans and e-Vol DX software showed satisfactory consistency with the direct assessment using the digital torque meter, offering an additional tool to evaluate implant component loosening and structural deformations.

Genotoxicity in the oral cells of older people from a Brazilian rural area: a population-based study

Abstract The purpose of this population-based, observational, and cross-sectional study was to evaluate alterations in the oral cells of a population of older people from a Brazilian rural area, using the micronucleus technique to investigate possible associated genotoxic factors. A questionnaire was applied and clinical examination and collection of oral mucosal cells were performed for all older people (≥ 60 years) from a town in southern Brazil. Demographic and socioeconomic variables, deleterious habits (drinking and tobacco use), presence of gastro-oesophageal reflux disease (GERD), and the use of proton pump inhibitors (PPIs) were considered the exposure variables, whereas metanuclear changes (MCs) and the prevalence of cell micronuclei (MN) were considered outcomes. Out of 489 older people, 447 were included in the study, among whom 50.8% were men with a mean age of 70.9 years and 83.9% had a monthly family income greater than US$ 500.00. GERD symptoms were present in 36.2% of the individuals, and 29.1% used PPIs daily, 53.3% consumed alcoholic beverages, and 46.7% used tobacco. The analysis of 1,000 oral mucosal cells per subject showed a MN frequency of 0-2 per individual, and MCs were detected with an average of 15 units per individual (median = 11 per individual). Poisson regression did not show statistical association between the exposure variables and the outcomes (presence of MN and MCs), except for the use of PPIs, which was a protective factor for the prevalence of MN [PR 0.6 (CI 0.3-0,9)]. Age, sex, family income, tobacco use and drinking, and GERD were not associated with the number of MN and MCs in oral mucosal cells of the investigated older people.

A atuação da Odontologia em unidades de terapia intensiva no Brasil / The practice of dentistry in intensive care units in Brazil

RESUMO Objetivo: Avaliar a atuação odontológica em unidades de terapia intensiva. Métodos: Estudo observacional de enquete, por meio do envio de questionários via plataforma on-line de colaboração de pesquisa em terapia intensiva no Brasil (AMIBnet). A pesquisa foi realizada de junho a outubro de 2017. Os questionários, envolvendo 26 questões fechadas sobre os hospitais e a atuação odontológica nas unidades de terapia intensiva foram enviados para 4.569 profissionais de diversas especialidades atuantes nas unidades. Resultados: Obtivemos 203 questionários respondidos, resultando em uma taxa de resposta de 4,44%. A maior parte das respostas teve origem em unidades de terapia intensiva na Região Sudeste do país (46,8%). Hospitais públicos (37,9%) e privados (36,4%) tiveram participação semelhante nos resultados. Dos respondentes, 55% apontaram que um serviço de Odontologia à beira de leito estava presente, sendo prestado de maneiras diversas. Conclusão: Presença de Serviço de Odontologia e de treinamentos e protocolos de prestação de serviço em saúde bucal estiveram correlacionados. Os métodos de cuidados orais variaram sobremaneira entre as em unidades de terapia intensiva pesquisadas.

ABSTRACT Objective: To evaluate the practice of dentistry in intensive care units. Methods: An observational survey study was conducted in which questionnaires were sent via the online platform for collaboration in intensive care research in Brazil (AMIBnet). The study was carried out from June to October 2017. The questionnaires, which contained 26 closed questions about hospitals and dentistry practices in the intensive care units, were sent to 4,569 professionals from different specialties practicing in the units. Results: In total, 203 questionnaires were returned, resulting in a response rate of 4.44%. Most of the responses were from intensive care units in the Southeast region of the country (46.8%). Public hospitals (37.9%) and private hospitals (36.4%) had similar participation rates. Of the respondents, 55% indicated that a bedside dentistry service was present, and they were provided in different ways. Conclusion: The presence of dentistry services and oral health service delivery training and protocols were correlated. The oral care methods varied greatly among the intensive care units surveyed.

Influence of Different Intellectual Disability Levels on Caries and Periodontal Disease

Abstract Oral health care is fundamental to preserve the individual integrity and consequently influences the general health. This observational, cross-sectional and analytical study evaluated the oral condition of 129 intellectually disabled individuals from the Association of Parents and Friends of Exceptional Children (APAE) in three southern Brazilian cities. Dental caries (DMFT and dmft indices) and periodontal disease (PSR index) were evaluated considering the intellectual disability level. A questionnaire on socioeconomic status (income and education level) and the last visit to a dentist was answered by the subjects' parents/guardians. The data were statistically evaluated using analysis of variance (ANOVA) and Tukey test (α=0.05). The mean DMFT values were 2.27, 3.76 and 0.58 (p<0.05), and the mean dmft values were 1.48, 1.55 and 2.75, respectively for subjects with mild, moderate and severe disabilities. Regarding the PSR index, 43% of the subjects presented gingivitis without retention factor (no calculus or defective margins) with no significant differences among the three disability levels. Considering the population and the limitations of this study, the subjects presenting severe disabilities showed significantly lower mean DMFT values compared to other disability levels, probably because the caretakers are responsible for the oral hygiene of such subjects.

Resumo Os cuidados com a saúde bucal são de fundamental importância para a preservação da integridade do indivíduo e, consequentemente, refletem na saúde geral. Este estudo transversal, observacional e analítico avaliou a situação bucal de 129 alunos com deficiência intelectual matriculados na Associação de Pais e Amigos dos Excepcionais (APAE) de três municípios do sul do Brasil. Cárie dentária (índices CPO-D e ceo-d) e doença periodontal (índice PSR) foram avaliados considerando o nível de deficiência intelectual. Um questionário das condições socioeconômicas (renda e escolaridade) e última visita ao dentista foi respondida pelos pais/responsáveis. Os dados foram avaliados estatisticamente utilizando análise de variância (ANOVA) e teste Tukey (α=0,05). As médias no índice CPO-D foram de 2,27, 3,76 e 0,58 (p<0,05) e no índice ceo-d foram de 1,48, 1,55 e 2,75 para os alunos com deficiência leve, moderada e severa, respectivamente. Com relação ao índice PSR, 43% dos alunos apresentou gengivite sem fator de retenção (sem cálculo ou defeitos marginais), não tendo diferença estatística entre os três níveis de deficiência. Considerando a população e as limitações do estudo, observou-se que alunos com deficiência severa apresentaram índice CPO-D significativamente menor comparado com outros níveis de deficiência, provavelmente devido à higiene oral ser realizada pelos cuidadores/responsáveis.

Accuracy of color measurement of endondontically treated teeth after aging / Precisão da medição de cor de dentes tratados endodonticamente após envelhecimento

Objective: The aim of this study was to compare the accuracy of three different modes of a spectrophotometer (Vita Classical, 3D-Master and CIE L*a*b* system) in the evaluation of color alteration in endodontically treated teeth. Material and Methods: The root canal treatment of forty-five sound human canines was performed. Color measurements were performed before the endodontic treatment (baseline), and after 6 months of water storage. Shade matching was performed using a spectrophotometer (Vita Easyshade) in three different modes: Vita Classical, 3D-Master and CIE L*a*b* coordinates. The color change (ΔE value) for the three methods were assessed in each sample and analyzed by multiple linear regression analysis. L*, a* and b* values were analyzed by t-test. The significance level was set at 5%. Results: According to the digital evaluation, no statistically significant differences were found between the CIE L*a*b*,Vita Classical and 3D-Mastermodes. However, a significant difference was found (p < 0.001) for the ΔE values, with the CIE L*a*b* mode presenting greater accuracy to detect color alterations. Conclusion: CIE L *a*b* method properly correlates to Vita Classical and 3D-Master modes. However, Easyshade can easier detect color changes if used in the CIE L*a*b* mode, which leads to more accurate results.

Objetivo: O objetivo deste estudo foi comparar a precisão de três modos diferentes de um espectrofotômetro (Vita Classical, 3D-Master e sistema CIE L*a*b*) na avaliação da alteração de cor em dentes tratados endodonticamente. Materiais e Métodos: O tratamento endodôntico de quarenta e cinco caninos humanos foi realizado. Medições de cor foram realizadas, antes do tratamento endodôntico (imediatamente), e após 6 meses de armazenamento em água. Análise de cor foi realizado utilizando um espectrofotômetro (Vita Easyshade) em três diferentes modos: Vita Classical, 3D-Master e sistema CIE L*a*b*. A mudança de cor (valor ΔE) para os três métodos foram avaliadas em cada amostra e analisados através de análise de regressão linear múltipla. Valores de L*, a* e b* foram analisados através do teste-t. O nível de significância estabelecido foi de 5%. Resultados: De acordo com a avaliação digital, não foram encontradas diferenças significativas entre os métodos CIE L*a*b*,Vita Classical e 3D-Master. No entanto, uma diferença significativa foi encontrada (p < 0,001) para os valores de ΔE, com o modo CIE L*a*b* apresentando uma maior precisão para detectar alterações de cor. Conclusão: O método CIE L *a*b* correlaciona corretamente para os modos Vita Classical e 3D-Master. No entanto, o Easyshade pode detectar alterações de cor, mais facilmente quando utilizado no modo CIE L *a*b*, permitindo resultados mais precisos.

Uso de fibrina rica em plaquetas (PRF) no tratamento de perfurações da membrana sinusal / Use of platelet-rich fibrin (PRF) to treat sinus membrane perforations

A reabilitação de áreas edântulas sempre foi um desafio para os profissionais, em especial a posterior de maxila, pela pneumatização dos seios maxilares. Uma das complicações durante os procedimentos de levantamento sinusal são as perfurações da membrana. A fibrina rica em plaquetas (PRF), um concentrado de fatores de crescimento obtido a partir da centrifugação do sangue do paciente, tem a propriedade de acelerar o processo cicatricial, reparar as perfurações na membrana schneideriana e funcionar como material de preenchimento. O objetivo do presente estudo foi revisar a literatura e relatar um caso de selamento de perfuração de membrana sinusal utilizando membrana de fibrina (PRF) associada … hidroxiapatita bovina

Rehabilitation of edentulous areas has always been a challenge for dentists, especially on the posterior maxilla due to the pneumatization of the maxillary sinus. One of the complications during sinus lifting procedures is perforation of the membrane. The platelet-rich fibrin (PRF) is a complex of growth factors obtained from centrifuging the patient’s blood. It has the ability to accelerate the healing process and repair damages in the Schneiderian membrane, therefore, functioning as a filling material. The aim of this study was to perform a literature review and report a clinical case of sealing membrane perforation using PRF associated with bovine hydroxyapatite

Atendimento odontológico de pacientes surdo-cegos: enfrentando desafios / Dental care for deafblind patients: facing challenges

Introdução: a odontologia tem um papel muito importante na atenção à saúde dos pacientes surdo-cegos, porém, esbarra na falta de profissionais qualificados e estudos específicos nessa área. Objetivo: essa revisão de literatura tem por objetivo apresentar aos profissionais da odontologia informações sobre a surdo-cegueira, descrevendo conceitos, causas e classificações, assim como relatar os métodos de comunicação, a necessidade da inserção do odontólogo na equipe multiprofissional de atendimento aos surdo-cegos, definindo, por fim, metodologias que auxiliem no atendimento odontológico desses pacientes. Revisão de literatura: a atuação do cirurgião-dentista na equipe multiprofissional proporciona aos pacientes melhorias no seu desenvolvimento, por meio da criação de vínculos e de atividades que propiciem maior autonomia. Além disso, demonstra a deficiência de informação na área da surdo-cegueira, sendo o envolvimento da família fator fundamental para um prognóstico favorável no processo educacional, social e de comunicação. Considerações finais: o profissional, além do conhecimento técnico e científico em sua área de atuação, deve ter domínio do melhor meio de comunicação com seu paciente surdo-cego.

Evidências científicas para o diagnóstico e tratamento da DTM e a relação com a oclusão e a ortodontia / Scientific evidence for the diagnosis and treatment of TMD and its relation to occlusion and orthodontics

Introdução: Vários conceitos envolvem a etiologia da DTM e a relação com a oclusão e a ortodontia, o que tem sido objeto de discussão e controvérsias, dificultando o diagnóstico e a construção de uma terapêutica eficiente para a disfunção. O relacionamento dessas três áreas tem sido amplamente questionado e é muito provável que uma mudança de paradigma esteja acontecendo com relação à DTM. Revisão de literatura: A etiologia é complexa e multifatorial, por isso, a tentativa de isolar uma causa universal não tem sido bem-sucedida. Os sinais e sintomas podem se manifestar de várias formas e, ainda, terapias inadequadas podem gerar iatrogenias, permitindo a cronificação da sintomatologia. O objetivo deste trabalho foi apresentar as informações existentes sobre o universo da DTM, considerando seu caráter fisiológico, etiológico, métodos diagnósticos e as diferentes formas de tratamento. Além disso, apresenta possíveis relações com outras áreas da odontologia, especialmente a oclusão e a ortodontia, por meio de uma revisão de literatura em bases de dados nacionais e internacionais (PubMed, Scielo, Bireme e Google Acadêmico). Considerações finais: Embora controversas, as evidências científicas parecem não suportar a relação ortodontia/DTM, bem como a relação oclusão/DTM. Apesar disso, é importante ressaltar que os tratamentos oclusal e ortodôntico, corretamente conduzidos, tem papel imprescindível na odontologia, pois estão envolvidos em diversos outros aspectos relevantes para a função e estética do sistema estomatognático e, portanto, não devem ser negligenciados pelos profissionais da odontologia.

Histopathological analysis of corticosteroid-antibiotic preparation and propolis paste formulation as intracanal medication after pulpectomy: an in vivo study

Intracanal medication in pulpectomy therapy is used between appointments with the objective of reducing pain and inflammatory processes in pulp and periapical tissues. Propolis has been known as a natural antibiotic and has been subject of medical and dental research due to its therapeutic properties such as antibiotic, analgesic and anti-inflammatory effects. OBJECTIVE: The aim was to carry out an in vivo evaluation of the periapical tissue response to propolis paste when used as an intracanal medication in the teeth of dogs after pulpectomy. MATERIAL AND METHODS: 72 dog's incisors were selected for the experiment. After biomechanical preparation the root canal was filled with a corticosteroid-antibiotic preparation, experimental propolis paste, non-medicament (negative control) or non-pulpectomy at all (positive control). The medications were left inside the root canal for 7, 14 or 28 days. At the end of the experimental period histological sections were prepared and all laboratories processes for Harris hematoxylin and eosin staining was proceeded followed by the analysis using an optical microscope. Sections were classified according to a score representing the inflammatory events observed: the presence of polymorphonuclear neutrophils, polymorphonuclear eosinophils, lymphocytes and plasma cells, macrophages and/or giant cells, fibrous condensation and abscesses. RESULTS: There were statistically significant differences between the tissue reactions caused by the two substances being tested, after different experimental periods, with the periapical tissue that was in contact with propolis paste exhibiting fewer inflammatory reactions in comparison to corticosteroid-antibiotic preparation. CONCLUSIONS: The low tissue responses from propolis paste suggest that this material could be considered as an option for root canal medication after pulpectomy.

Radiographic evaluation of furcal perforations sealed with different materials in dogs' teeth

OBJECTIVE: The objective of this work was to evaluate, using radiographic images, the behavior of four materials used to repair root perforations in dogs' teeth. Material and METHODS: Second and third premolars of 6 dogs were used. The 48 teeth were randomly divided into 4 groups (n=12) and the perforations were sealed with one of the following materials: MTA, AH Plus, Vitremer and gutta-percha. Dogs were submitted to general anesthesia, teeth were radiographed and pulp was accessed. Perforations were done, at the maximum curve of the pulp floor, sealed and the accessed coronal cavity was filled with glass ionomer cement (Vidrion R). After 90 days, the dogs were sacrificed and the last x-ray image was taken. Images were analyzed for the presence/absence of periodontal lesions at the perforation region. Data were analyzed statistically by chi-square test at 5 percent significance level. RESULTS: There were no statistically significant differences (p>0.05) among AH Plus, Vitremer and gutta-percha groups. MTA produced the smallest number of periodontal lesions (p<0.05). CONCLUSIONS: It may be concluded that none of the tested materials was able to preserve the integrity of the periodontal tissues in the furcation region, and the use of MTA resulted in the least formation of adjacent periodontal bone lesions revealed by the radiographic comparisons.

Fluoride Release from Restorative Materials

The aim of this study was to evaluate in vitro fluoride (F) release from 4 restorative materials (3M ESPE): Ketak Molar Easymix [KME - conventional glass ionomer cement (GIC)]; Rely-X luting 2 [RL2 - resin-modified GIC (RMGIC)]; Vitremer (VIT- RMGIC); and Filtek Z250 [Z250 - negative control]. Disc-shaped specimens were fabricated according to the manufacturer’s instructions and placed into 10 mL of reverse osmosis water at 37°C until the analyses were done using a liquid membrane for selective F ion electrode (Orion 710). F release was evaluated every 6 h in the first day and thereafter daily during 28 days (d). The results were analyzed statistically by two-way ANOVA and Tukey’s test (α=0.05). Mean F release and standard deviation values (in ppm) were: KME: 6 h- 0.34 ± 0.04; 24 h- 1.22 ± 0.30; 7 d- 0.29 ± 0.09; 14 d- 0.20 ± 0.04; 28 d- 0.16 ± 0.01; RL2: 6 h- 2.46 ± 0.48; 24 h-12.33 ± 2.93; 7 d- 1.37 ± 0.38; 14 d- 0.80 ± 0.13; 28 d- 0.80 ± 0.21; VIT: 6 h- 0.98 ± 0.35; 24 h- 4.35 ± 1.22; 7 d- 0.66 ± 0.23; 14 d- 0.40 ± 0.07; 28 d- 0.39 ± 0.08; Z250: 6 h- 0.029 ± 0.001; 24 h- 0.024 ± 0.009; 7 d- 0.023 ± 0.004; 14 d- 0.025 ± 0.001; 28 d- 0.028 ± 0.001. RL2 RMGIC released more F than the other materials in all periods. The greatest release of F occurred in the first 24 h.

O objetivo deste estudo foi avaliar, in vitro, a liberação de flúor (F) de 4 materiais restauradores (3M-ESPE): KME cimento de ionômero de vidro convencional (CIV) (Ketak Molar Easymix); RX2- GIC modificado por resina (RMGIC) (Rely-X luting 2); VIT-RMGIC (Vitremer); -resina composta Z250 (controle negativo) (Filtek Z250). As amostras foram confeccionadas de acordo com as instruções do fabricante e colocadas em 10 mL de água destilada 37°C até as leituras, que foram feitas utilizando um eletrodo de íon seletivo de fluoreto de membrana líquida (Orion 710). A liberação de flúor foi avaliada a cada 6 h no primeiro dia e, diariamente durante 28 dias (d). Os resultados foram analisados estatisticamente usando ANOVA a dois critérios e teste de Tukey. A média e desvio padrão de liberação de F, valores (em ppm) foram: KME: 6 h- 0,34 ± 0,04; 24 h- 1,22 ± 0,30; 7 d- 0,29 ± 0,09; 14 d- 0,20 ± 0,04; 28 d- 0,16 ± 0,01; RL2: 6 h- 2,46 ± 0,48; 24 h- 12,33 ± 2,93; 7 d- 1,37 ± 0,38; 14 d- 0,80 ± 0,13; 28 d- 0,80 ± 0,21; VIT: 6 h- 0,98 ± 0,35; 24 h- 4,35 ± 1,22; 7 d- 0,66 ± 0,23; 14 d- 0,40 ± 0,07; 28 d- 0,39 ± 0,08; Z250: 6 h- 0,029 ± 0,001; 24 h- 0,024 ± 0,009; 7 d- 0,023 ± 0,004; 14 d- 0,025 ± 0,001; 28 d- 0,028 ± 0,001. Concluiu-se que RL2 liberou mais F do que os outros materiais em todos os períodos. A maior liberação de F ocorreu nas primeiras 24 h.

Influence of different restorative techniques on marginal seal of class II composite restorations

OBJECTIVE: To evaluate the gingival marginal seal in class II composite restorations using different restorative techniques. MATERIAL AND METHODS: Class II box cavities were prepared in both proximal faces of 32 sound human third molars with gingival margins located in either enamel or dentin/cementum. Restorations were performed as follows: G1 (control): composite, conventional light curing technique; G2: composite, soft-start technique; G3: amalgam/composite association (amalcomp); and G4: resin-modified glass ionomer cement/composite, open sandwich technique. The restored specimens were thermocycled. Epoxy resin replicas were made and coated for scanning electron microscopy examination. For microleakage evaluation, teeth were coated with nail polish and immersed in dye solution. Teeth were cut in 3 slices and dye penetration was recorded (mm), digitized and analyzed with Image Tool software. Microleakage data were analyzed statistically by non-parametric Kruskal-Wallis and Mann-Whitney tests. RESULTS: Leakage in enamel was lower than in dentin (p<0.001). G2 exhibited the lowest leakage values (p<0.05) in enamel margins, with no differences between the other groups. In dentin margins, groups G1 and G2 had similar behavior and both showed less leakage (p<0.05) than groups G3 and G4. SEM micrographs revealed different marginal adaptation patterns for the different techniques and for the different substrates. CONCLUSION: The soft-start technique showed no leakage in enamel margins and produced similar values to those of the conventional (control) technique for dentin margins.

Flexural strength and hardness of direct and indirect composites

The objective of this study was to evaluate the flexural strength (óf) and hardness (H) of direct and indirect composites, testing the hypotheses that direct resin composites produce higher óf and H values than indirect composites and that these properties are positively related. Ten bar-shaped specimens (25 mm x 2 mm x 2 mm) were fabricated for each direct [D250 - Filtek Z250 (3M-Espe) and D350 - Filtek Z350 (3M-Espe)] and indirect [ISin - Sinfony (3M-Espe) and IVM - VitaVM LC (Vita Zahnfabrik)] materials, according to the manufacturer's instructions and ISO4049 specifications. The óf was tested in three-point bending using a universal testing machine (EMIC DL 2000) at a crosshead speed of 0.5 mm/min (ISO4049). Knoop hardness (H) was measured on the specimens' fragments resultant from the óf test and calculated as H = 14.2P/l², where P is the applied load (0.1 kg; dwell time = 15 s) and l is the longest diagonal of the diamond shaped indent (ASTM E384). The data were statistically analyzed using Anova and Tukey tests (á = 0.05). The mean óf and standard deviation values (MPa) and statistical grouping were: D250 - 135.4 ± 17.6a; D350 - 123.7 ± 11.1b; ISin - 98.4 ± 6.4c; IVM - 73.1 ± 4.9d. The mean H and standard deviation values (kg/mm²) and statistical grouping were: D250 - 98.12 ± 1.8a; D350 - 86.5 ± 1.9b; ISin - 28.3 ± 0.9c; IVM - 30.8 ± 1.0c. The direct composite systems examined produce higher mean óf and H values than the indirect composites, and the mean values of these properties were positively correlated (r = 0.91), confirming the study hypotheses.