CAD/CAM system influence marginal fit of different ceramic types?

OBJECTIVE: This study aimed to evaluate the marginal fit of zirconia and lithium disilicate ceramic restorations processed by computer-aided design (CAD)/computer-aided manufacturing (CAM) system. MATERIALS AND METHODS: Ten models were prepared from a metal die, on which scanning was carried out to obtain the virtual model for the processing of zirconia and lithium disilicate ceramics using the CAD/CAM technique. Gypsum models were fabricated and used for scanning the restorations. The infrastructures were designed using software, and CAD/CAM was used to fabricate the restorations (n = 10). The analysis of the marginal discrepancy was measured at 12 points of the margin using the original metallic die. For each crown, an arithmetic average of the discrepancy values was obtained. RESULTS: The marginal fit of the copings of lithium disilicate was 133.10 ± 26.87 µm and zirconia was 127.34 ± 47.97 µm. There was no statistically significant difference (P = 0.7709) between the materials. CONCLUSION: The marginal fit is similar between lithium disilicate and zirconia ceramics milled in the CAD/CAM system used.

O OSCE na avaliação clínica odontológica: relato de experiência com estudantes de graduação / OSCE in Dental clinical evaluation: the report of an experience with undergraduate students

O Exame Clínico Objetivo e Estruturado (OSCE) é um exame organizado em estações que simulam a realidade clínica e os estudantes são avaliados em tarefas específicas como anamnese, exame físico, comunicação com paciente, procedimentos clínicos não invasivos, entre outras. É realizado o rodízio de alunos e um ou dois examinadores pontuam o desempenho dos mesmos em cada tarefa, com critérios e tempo previamente determinados. O objetivo desse estudo foi relatar a experiência de aplicação do OSCE na graduação e como estruturá-lo. O primeiro OSCE aplicado pelo curso de Odontologia da Universidade do Oeste Paulista (UNOESTE) para alunos de graduação foi no ano de 2016, com o objetivo de avaliação de competências dos alunos que ingressariam nas clínicas no semestre seguinte. A avaliação foi aplicada aos 70 alunos do final do terceiro ano e os conteúdos selecionados foram Dentística, Periodontia, Endodontia, Radiologia, Biossegurança, Anestesiologia e Diagnóstico Bucal. O OSCE pode ser considerado uma técnica de avaliação adequada para o alcance de competências clínicas na formação de cirurgiões-dentistas, por proporcionar ao aluno de graduação a vivência de atividades similares à realidade que enfrentará no atendimento clínico e em sua futura atuação profissional. Esse método de avaliação propicia aos estudantes a oportunidade de serem avaliados de forma mais objetiva e poder aprender com o feedback do seu desempenho no exame (AU).

The Objective and Structured Clinical Examination (OSCE) is an exam organized in stations that simulate clinical reality and students are evaluated in specific tasks such as anamnesis, physical examination, communication with patients, noninvasive clinical procedures, among others. Students rotated through stations, and one or two examiners score their performance in each task, with predetermined criteria and time. The objective of this study was to report on the experience of applying the OSCE in undergraduate and how to structure it. The first OSCE applied for Dental undergraduate students at Universidade do Oeste Paulista (UNOESTE) was in 2016, with the objective of evaluating the competencies of the students who would enter the clinics in the following semester. The evaluation was applied to 70 students at the end of the third year and the contents selected were Restorative Dentistry, Periodontics, Endodontics, Radiology, Biosafety, Anesthesiology and Oral Diagnosis. The OSCE can be considered an adequate evaluation technique for the attainment of clinical competences in the training of dental surgeons, as it provides the undergraduate student with the experience of activities similar to the reality he will face in clinical care and his future professional performance. This assessment method gives students the opportunity to be evaluated more objectively and to learn from feedback on their exam performance (AU).

A plataforma Moodle no treinamento de estudantes de Odontologia na avaliação de restaurações classe II em resina composta / Dental students training on the evaluation of class II composite restorations using the Moodle platform

O objetivo do estudo foi analisar o padrão de conduta de acadêmicos de Odontologia frente a restaurações classe II em resina composta cuja situação clínica seja de caráter duvidoso. Deste modo, pode-se detectar dificuldades comuns dos estudantes na tomada de decisão da conduta clínica, por meio de critérios de avaliação padronizados, bem como aperfeiçoar uma metodologia auxiliar de ensino digital baseada na plataforma Moodle. Participaram da pesquisa 65 estudantes da disciplina de Dentística que já haviam recebido treinamento teórico sobre critérios clínicos para avaliação de restaurações conforme FDI (World Dental Federation). A coleta de dados foi feita por meio de questionários disponíveis no site Aprender Unoeste (plataforma Moodle). Os estudantes analisaram 22 imagens de restaurações classe II em resina composta disponíveis no site observando os seguintes itens: parâmetros estéticos (brilho superficial, manchamento superficial e marginal, correspondência de cor e translucidez), parâmetros funcionais (fratura do material e retenção, adaptação marginal, forma anatômica proximal/contorno) e parâmetros biológicos (recorrência de cáries e integridade dental). A média de acertos dos alunos foi 6,3±0,7 (sobre pontuação máxima = 10), sendo que os parâmetros estéticos apresentaram menor percentual de acertos. Após o preenchimento do questionário os estudantes obtinham o feedback imediato de suas avaliações, tendo então a possibilidade de verificar seus erros e qual seria a resposta adequada. O estudo detectou dificuldades dos estudantes de Odontologia na análise de restaurações em resina composta e possibilitou que estes adquirissem experiência visual clínica, desenvolvendo seu senso crítico, como auxílio de novas metodologias de ensino-aprendizagem (AU).

The study aimed to evaluate the clinical conduct of dental undergraduate students regarding unsatisfactory Class II composite restorations with doubtful prognosis, in order to detect their difficulties and to improve learning methods using a Moodle online platform. A total of 65 sixth semester students were enrolled, they were attending Operative-Restorative Dentistry discipline and received previous theoretical training on restorations evaluation according FDI (World Dental Federation) criteria and randomly selected as volunteers. Data was collected using a questionnaire available on a specific online Moodle platform. Students analyzed 22 digital images of class II composite restorations observing aesthetic parameters (i.e., surface gloss, surface and marginal staining, color matching and translucency), anatomical aesthetic form, functional parameters (i.e., restoration fracture and retention, marginal adaptation, proximal anatomical shape/contour) and biological parameters (i.e., recurrence of caries and tooth integrity). The maximum individual score for correct answers was established as 10 points. Immediate feedback was provided allowing students to check the appropriate responses once the questionnaire was finished. The average of correct answers was 6.3 (0,7 standard deviation). Graduation students present a considerable high difficulty to determine the clinical success of composite restorations. The proposed new teaching/learning methodology enhances the visual experience and the critical contributes to accelerate the learning curve on this topic (AU).

Optical impression systems for CAD-CAM restorations.

Computer-aided design/computer-aided manufacturing images can be taken through either direct or indirect imaging. For the indirect systems, the digitalization is obtained from the impression material or cast, and for the direct ones the image is taken directly from the mouth using intraoral scanners.The direct acquisition systems have been constantly improved because these are less invasive, quicker, and more precise than the conventional method. Besides, the digital images can be easily stored for a long time. Therefore, the aim of this paper was to describe and discuss based on the literature the main direct image acquisition systems available on the market: CEREC Bluecam (Sirona), Lava C.O.S. System (3M ESPE), iTero System (Cadent/Straumann), and E4D System (D4D Technologies).

Caracterização in vitro de um novo sistema de resina composta de laboratório / In vitro characterization of a new laboratory composite resin

Objetivo: este estudo caracterizou algumas propriedades de uma resina composta de processamento laboratorial (Resilab, Wilcos do Brasil), indicada para confecção de coroas com e sem metal, pontes anteriores e posteriores, inlays, onlays e facetas laminadas. Metodologia: as propriedades avaliadas foram rugosidade superficial, dureza, resistência à flexão, resistência adesiva a três ligas metálicas (Au, NiCr e CoCr) e microinfiltração da interface resina/metal. Todos os espécimes foram submetidos a dois ciclos de polimerização, conforme instruções do fabricante. Dez espécimes circulares (4x3 mm) foram preparados para os testes de dureza (VHN) e rugosidade superficial (Ra). A resistência flexural em três pontos (MPa) foi medida a partir de espécimes retangulares (10x5x2 mm), sob velocidade de 1 mm/min. Os ensaios que envolveram ligas metálicas (resistência adesiva e microinfiltração) foram submetidos à análise estatística (p<0,05) (Anova, Tukey, Kruskal-Wallis). Resultados: não houve diferenças entre as médias de resistência de união. Quanto à infiltração marginal, o grupo CoCr diferiu dos grupos Au e NiCr em espécimes sem retenção mecânica e submetidos a ciclagem térmica. Conclusão: considerando os resultados deste estudo in vitro e a literatura pesquisada, o sistema Resilab mostrou comportamento satisfatório quanto às propriedades estudadas. A resistência de união não dependeu da liga metálica utilizada.

Aim: this study aimed to determine some of the properties of a laboratory composite indicated for metallic and non-metallic crowns, anterior and posterior bridges, inlays, onlays and laminate veneers. Methology: the properties evaluated were surface roughness, flexural strength, shear bond strength to three metal alloys and the microleakage at the composite/ metal interface. All specimens were subjected to cycles of polymerization, according the manufacturer instructions. Ten round specimens (4x3 mm) were prepared for hardness (VHN) and surface roughness tests (Ra). The three-point flexural strength was measured on rectangular shaped specimens (10x5x2 mm), at 1 mm/min speed. The experiments involving dental alloys (bond strength and microleakage) were submitted to statistical analysis (p<0, 05) (Anova, Tukey, Kruskal-Wallis). Results: there were no statistically significant diferences between the bond strength means. As for the marginal leakage, the CoCr group differed of the Au and NiCr groups in specimens without mechanical retention and subjected to thermocycling. Conclusion: according to our results and the literature search, the Resilab system showed satisfactory performance regarding the properties evaluated. The bond strength was not dependable on the metal alloy used.

Adhesive cementation of zirconia posts to root dentin: evaluation of the mechanical cycling effect.

This study evaluated the effect of mechanical cycling on the bond strength of zirconia posts to root dentin. Thirty single-rooted human teeth were transversally sectioned to a length of 16 mm. The canal preparation was performed with zirconia post system drills (CosmoPost, Ivoclar) to a depth of 12 mm. For post cementation, the canals were treated with total-etch, 3-steps All-Bond 2 (Bisco), and the posts were cemented with Duolink dual resin cement (Bisco). Three groups were formed (n = 10): G1 - control, no mechanical cycling; G2 - 20,000 mechanical cycles; G3 - 2,000,000 mechanical cycles. A 1.6-mm-thick punch induced loads of 50 N, at a 45 degrees angle to the long axis of the specimens and at a frequency of 8 Hz directly on the posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis of the teeth, generating 2-mm-thick slices, approximately (5 sections per teeth), which were subjected to the push-out test in a universal testing machine at a 1 mm/min crosshead speed. The push-out bond strength was affected by the mechanical cycling (1-way ANOVA, p = .0001). The results of the control group (7.7 +/- 1.3 MPa) were statistically higher than those of G2 (3.9 +/- 2.2 MPa) and G3 (3.3 +/- 2.3 MPa). It was concluded that the mechanical cycling damaged the bond strength of zirconia posts to root dentin.

Evaluation of light transmission through translucent and opaque posts.

OBJECTIVES: The transmission of light through translucent posts was observed, and the microhardness of light-cured cement used to secure these posts was evaluated at different depths. METHODS: Fifteen single-rooted standard bovine teeth, 16 mm in size, were used. The root canals were prepared using #3 drills Light-Post (five teeth) and Aestheti Post (five teeth) systems (BISCO), with a working-length of 12 mm. In five teeth, translucent posts were cemented (Light-Post #2), while another five teeth received opaque posts (Aestheti Post #2). The roots were painted with black nail varnish to prevent the passage of light through the lateral walls of the roots. The root canals of all the specimens were treated with the All-Bond 2 adhesive system (BISCO) and cemented with light-cured cement (Enforce, Dentsply). All the roots were transversally cut to obtain six specimens 1.5 mm thick. Every two sections corresponded to a specific region of the root (cervical, middle, apical), making it possible to observe the cement microhardness at different levels. The groups (n = 10) were defined as: GI: translucent post (TP)/cervical region; G2: TP/middle region; G3: TP/apical region; G4: Opaque post (OP)/cervical region; G5: OP/middle region; G6: PO/apical region. Five root canals were only filled with cement for use as a control (G7). Then, Vickers microhardness analyses were performed. RESULTS: In G3, G5 and G6, the cement was not sufficiently hard to allow for microhardness analysis. When submitted to the ANOVA test, G1 (35.07), G2 (24.28) and G4 (28.64) presented no statistical differences. When the previous groups were compared to G7 (51.00) using the Kruskal-Wallis test, a statistical difference was found. CONCLUSION: Translucent posts allow cement polymerization up to the middle portion of the root.

Adhesive cementation of zirconia posts to root dentin: evaluation of the mechanical cycling effect

This study evaluated the effect of mechanical cycling on the bond strength of zirconia posts to root dentin. Thirty single-rooted human teeth were transversally sectioned to a length of 16 mm. The canal preparation was performed with zirconia post system drills (CosmoPost, Ivoclar) to a depth of 12 mm. For post cementation, the canals were treated with total-etch, 3-steps All-Bond 2 (Bisco), and the posts were cemented with Duolink dual resin cement (Bisco). Three groups were formed (n = 10): G1 - control, no mechanical cycling; G2 - 20,000 mechanical cycles; G3 - 2,000,000 mechanical cycles. A 1.6-mm-thick punch induced loads of 50 N, at a 45° angle to the long axis of the specimens and at a frequency of 8 Hz directly on the posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis of the teeth, generating 2-mm-thick slices, approximately (5 sections per teeth), which were subjected to the push-out test in a universal testing machine at a 1 mm/min crosshead speed. The push-out bond strength was affected by the mechanical cycling (1-way ANOVA, p = .0001). The results of the control group (7.7 ± 1.3 MPa) were statistically higher than those of G2 (3.9 ± 2.2 MPa) and G3 (3.3 ± 2.3 MPa). It was concluded that the mechanical cycling damaged the bond strength of zirconia posts to root dentin.

Effect of mechanical cycling on the push-out bond strength of fiber posts adhesively bonded to human root dentin.

This study evaluated the effect of mechanical cycling on the bond strength of fiber posts bonded to root dentin. The hypotheses examined were that bond strength is not changed after fatigue testing and bond strength does not present vast variations according to the type of fiber post. Sixty crownless, single-rooted human teeth were endodontically treated, with the space prepared at 12 mm. Thirty specimens received a quartz fiber post (Q-FRC) (DT Light-Post), and the remaining 30 specimens received a glass fiber post (G-FRC) (FRC Postec Plus). All the posts were resin luted (All Bond+Duolink), and each specimen was embedded in a cylinder with epoxy resin. The specimens were divided into six groups: G1- Q-FRC+no cycling; G2- Q-FRC+20,000 cycles (load: 50N; angle of 450; frequency: 8Hz); G3- Q-FRC+2,000,000 cycles; G4- G-FRC+no cycling; G5- G-FRC+20,000 cycles; G6- G-FRC+2,000,000 cycles. The specimens were cut perpendicular to their long axis, forming 2-mm thick disc-samples, which were submitted to the push-out test. ANOVA (alpha = .05) revealed that: (a) Q-FRC (7.1 +/- 2.2MPa) and G-FRC (6.9 +/- 2.1MPa) were statistically similar (p = 0.665); (b) the "no cycling" groups (7.0 +/- 2.4MPa), "20,000 cycles" groups (7.0 +/- 2.1MPa) and "2,000,000 cycles" groups (7.0 +/- 2.0MPa) were statistically similar (p = 0.996). It concluded that mechanical cycling did not affect the bond strength of two fiber posts bonded to dentin.

Effects of mechanical cycling on the bonding of zirconia and fiber posts to human root dentin.

PURPOSE: To evaluate the effect of cyclical mechanical loading on the bond strength of a fiber and a zirconia post bonded to root dentin. MATERIALS AND METHODS: Forty single-rooted human teeth (maxillary incisors and canines) were sectioned, and the root canals were prepared at 12 mm. Twenty randomly seleced specimens received a quartz fiber post (FRC) (D.T. Light-Post) and 20 others received a zirconia post (ZR) (Cosmopost). The posts were resin luted (All Bond 2 + resin cement Duo-link) and each specimen was embedded in epoxy resin inside a PVC cylinder. Ten specimens with FRC post and 10 specimens with ZR post were submitted to fatigue testing (2,000,000 cycles; load: 50 N; angle of 45 degrees; frequency: 8 Hz), while the other 20 specimens were not fatigued. Thus, 4 groups were formed: G1: FRC+O cycles; G2: FRC+2,000,000 cycles; G3: ZR+O cycles; G4: ZR+2,000,000 cycles. Later, the specimens were cut perpendicular to their long axis to form 2-mm-thick disk-shaped samples (4 sections/specimen), which were submitted to the push-out test (1 mm/min). The mean bond strength values (MPa) were calculated for each tooth (n = 10) and data were submitted to statistical analysis (alpha = 0.05). RESULTS: Two-way ANOVA revealed that the bond strength was significantly affected by mechanical cycling (p = 0.0014) and root post (p = 0.0325). The interaction was also statistically significant (p = 0.0010). Tukey's test showed that the mechanical cycling did not affect the bonding of FRC to root dentin, while fatigue impaired the bonding of zirconium to root dentin. CONCLUSION: (1) The bond strength of the FRC postto root dentin was not reduced after fatigue testing, whereas the bonding of the zirconia post was significantly affected by the fatigue. (2) Cyclical mechanical loading appears to damage the bond strength of the rigid post only.

Effect of surface conditioning methods on the microtensile bond strength of resin composite to composite after aging conditions.

OBJECTIVES: This study evaluated the effect of two different surface conditioning methods on the repair bond strength of a bis-GMA-adduct/bis-EMA/TEGDMA based resin composite after three aging conditions. METHODS: Thirty-six composite resin blocks (Esthet X, Dentsply) were prepared (5 mm x 6 mm x 6 mm) and randomly assigned into three groups for aging process: (a) immersion in citric acid (pH 3.0 at 37 degrees C, 1 week) (CA); (b) boiling in water for 8h (BW) and (c) thermocycling (x5000, 5-55 degrees C, dwell time: 30s) (TC). After aging, the blocks were assigned to one of the following surface conditioning methods: (1) silica coating (30 microm SiO(x)) (CoJet, 3M ESPE)+silane (ESPE-Sil) (CJ), (2) phosphoric acid+adhesive resin (Single Bond, 3M ESPE) (PA). Resin composite (Esthet.X) was bonded to the conditioned substrates incrementally and light polymerized. The experimental groups formed were as follows: Gr1:CA+PA; Gr2:CA+CJ; Gr3:BW+PA; Gr4: BW+CJ; Gr5:TC+PA; Gr6: TC+CJ. The specimens were sectioned in two axes (x and y) with a diamond disc under coolant irrigation in order to obtain non-trimmed bar specimens (sticks, 10 mm x 1 mm x 1 mm) with 1 mm(2) of bonding area. The microtensile test was accomplished in a universal testing machine (crosshead speed: 0.5 mm min(-1)). RESULTS: The means and standard deviations of bond strength (MPa+/-S.D.) per group were as follows: Gr1: 25.5+/-10.3; Gr2: 46.3+/-10.1; Gr3: 21.7+/-7.1; Gr4: 52.3+/-15.1; Gr5: 16.1+/-5.1; Gr6, 49.6+/-13.5. The silica coated groups showed significantly higher mean bond values after all three aging conditions (p<0.0001) (two-way ANOVA and Tukey tests, alpha=0.05). The interaction effect revealed significant influence of TC aging on both silica coated and acid etched groups compared to the other aging methods (p<0.032). Citric acid was the least aggressive aging medium. SIGNIFICANCE: Chairside silica coating and silanization provided higher resin-resin bond strength values compared to acid etching with phosphoric acid followed by adhesive resin applications. Thermocycling the composite substrates resulted in the lowest repair bond strength compared to citric acid challenge or boiling in water.

Microtensile bond strength between a quartz fiber post and a resin cement: effect of post surface conditioning.

PURPOSE: To test the bond strength between a quartz-fiber-reinforced composite post (FRC) and a resin cement. The null hypothesis was that the bond strength can be increased by using a chairside tribochemical silica-coating system. MATERIALS AND METHODS: Thirty quartz-FRCs (Light-Post) were divided into 3 groups according to the post surface treatment: G1) Conditioning with 32% phosphoric acid (1 min), applying a silane coupling agent; G2) etching with 10% hydrofluoric acid (1 min), silane application; G3) chairside tribochemical silica coating method (CoJet System): air abrasion with 30-microm SiOx-modified Al2O3 particles, silane application. Thereafter, the posts were cemented into a cylinder (5 mm diameter, 15 mm height) with a resin cement (Duo-Link). After cementation, the specimens were stored in distilled water (37 degrees C/24 h) and sectioned along the x and y axes with a diamond wheel under cooling (Lab-cut 1010) to create nontrimmed bar specimens. Each specimen was attached with cyanoacrylate to an apparatus adapted for the microtensile test. Microtensile testing was conducted on a universal testing machine (1 mm/min). The data obtained were submitted to the one-way ANOVA and Tukey test (alpha = 0.05). RESULTS: A significant influence of the conditioning methods was observed (p < 0.0001). The bond strength of G3 (15.14 +/- 3.3) was significantly higher than the bond strengths of G1 (6.9 +/- 2.3) and G2 (12.60 +/- 2.8) (p = 0.000106 and p = 0.002631, respectively). Notwithstanding the groups, all the tested specimens showed adhesive failure between the resin cement and FRC. CONCLUSION: The chairside tribochemical system yielded the highest bond strength between resin cement and quartz-fiber post. The null hypothesis was accepted (p < 0.0001).

Effect of silica coating on flexural strength of fiber posts.

PURPOSE: Fiber-reinforced composite (FRC) posts can be air-abraded to obtain good attachment to the resin cement. This study tested the effect of silica coating on the flexural strength of carbon, opaque, and translucent quartz FRC posts. MATERIALS AND METHODS: Six experimental groups of FRC posts (n=10 per group) were tested, either as received from the manufacturer or after chairside silica coating (30-microm CoJet-Sand). RESULTS: There was no significant difference in the flexural strength of nonconditioned (504 to 525 MPa) and silica-coated (514 to 565 MPa) specimens (P > .05) (analysis of variance). The type of post did have a significant effect on flexural strength (P < .05). CONCLUSION: Chairside silica coating did not affect the flexural strength of both carbon and quartz FRC posts.

Effect of post length on the fatigue resistance of bovine teeth restored with bonded fiber posts: a pilot study.

This study evaluated the influence of the cementation length of glass fiber-reinforced composite (FRC) on the fatigue resistance of bovine teeth restored with an adhesively cemented FRC. Thirty roots of single-rooted bovine teeth were allocated to 3 groups (n = 10), according to the ratio of crown length/root length (post cementation length): group 1 = 2/3, group 2 = 1/2, and group 3 = 1/1. The roots were prepared, the fiber posts (FRC Postec Plus) were cemented, and the specimens were submitted to 2 million mechanical cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture, and data were submitted to statistical analysis. All specimens were resistant to fatigue. Taking into account the methodology and results of this study, the evaluated fiber posts can be cemented based on the ratio of crown/root at 1/1. Further clinical studies must be conducted to verify this ratio.

Efeito do tempo de condicionamento da superfície cerâmica sobre a resistência / Effect of the conditioning time of the ceramic surface on bond strength between a fluorapatite ceramic and a resin cement

O objetivo deste estudo foi avaliar a resistência de união entre uma cerâmica sintética de fluorapatita e leucita livre de feldspato e um cimento resinoso dual, variando o tempo de condicionamento ácido da superfície da cerâmica. Foram confeccionados 16 blocos de cerâmica (IPS d. SIGN- Ivoclar-Vivadent) que foram divididos aleatoriamente em 2 grupos (n=8), conforme o tempo de condicionamento ácido da superfície cerâmica: G1 - condicionamento durante 30 segundos com ácido fluorídrico 10%, seguido da aplicação do agente silano (Primer ceramic, 3M/Espe); G2: condicionamento com ácido fluorídrico 10% durante 2 minutos, seguido da aplicação do silano (Primer ceramic, 3M/Espe). Os blocos de cerâmica foram unidos a blocos de resina composta, recém confeccionados, (Fill Magic, Vigodent) com o cimento resinoso Rely X (3M/Espe) sob uma carga de 750g. Os conjuntos foram armazenados em água por 24h e seccionados em dois eixos, x e y, obtendo-se corpos-de-prova (CP) com área de aproximadamente 0,7 mm2. Os CP foram submetidos ao ensaio de microtração a uma velocidade de 0,5 mm/min. Os resultados foram submetidos a duas análises estatísticas utilizando todos os CP, incluindo os com valores zero (G1 = 12,99 ± 6,7 MPa e G2 = 14,97 ± 3,7 MPa) e excluindo os com valores zero (G1 = 20,19 ± 3,8 MPa e G2 = 22,31 ± 2,8 MPa). Não foi observada diferença estatística entre os grupos em nenhuma das análises (p>0,05).

Evaluation of the flexural strength of carbon fiber-, quartz fiber-, and glass fiber-based posts.

This study investigated the flexural strength of eight fiber posts (one carbon fiber, one carbon/quartz fiber, one opaque quartz fiber, two translucent quartz fiber, and three glass fiber posts). Eighty fiber posts were used and divided into eight groups (n = 10): G1: C-POST (Bisco); G2: AESTHETI-POST (Bisco); G3: AESTHETI-PLUS (Bisco); G4: LIGHT-POST (Bisco); G5: D.T. LIGHT-POST (Bisco); G6: PARAPOST WHITE (Coltene); G7: FIBERKOR (Pentron); G8: REFORPOST (Angelus). All of the samples were tested using the three-point bending test. The averages obtained were submitted to the ANOVA and to Tukey's test (p < 0.05). The mean values (MPa) of the groups AESTHETI-POST-carbon/quartz fiber post (Bisco) and AESTHETI-PLUS-quartz fiber post (Bisco) were statistically similar and higher than the mean values of the other groups. The mean values of the groups C-POST-carbon fiber post (Bisco), LIGHT-POST-translucent quartz fiber post (Bisco), D.T. LIGHT-POST-double tapered translucent quartz fiber post (Bisco), PARAPOST WHITE-glass fiber post (Coltene) and FIBREKOR--glass fiber post (Pentron) were similar and higher than the group REFORPOST-glass fiber post (Angelus).

Avaliação da resistência adesiva entre uma cerâmica aluminizada e um cimento resinoso submetidos à ciclagem térmica / Effect of the thermocycling on bond strength of an aluminous ceramic to a resin cement

O objetivo este estudo foi avaliar o efeito da ciclagem térmica sobre a resistência adesiva entre a superfície cerâmica do In-Ceram (Vita-Zahnfabrik, bad sãckingen, Alemanha) e o cimento resinoso (Panavia F, Kuraray CO, Japao). Foram fabricados nove blocos cerâmicos com dimensoes de 5X6X6mm. Uma fas faces com 5X6mm de cada bloco cerâmico foi condicionada com uma cobertura triboquímica de sílica (Sistema Rocatec, ESPE- Seefeld - Alemanha) e em seguida cimentada com Panavia F a outro bloco idêntico de resina composta (Cleafil AP-X, Kuraray Co - Japao). Os nove grupos formados por cerâmica, cimento e resina composta foram cortados em 60 corpos-de-prova com dimensoes de 10X1X1mm e área adesiva que apresentava 1mm2+-0,1mm2. Os corpos-de-prova foram divididos em 3 grupos (n=20):G1 - armazenagem durante 14 dias em água destilada a 37ºC; G2 - 6000 ciclos térmicos (5ºC-55ºC, 30s em cada temperatura); G3 - 12000 ciclos térmicos (5ºC - 55ºC, 30s em cada temperatur). Após os condicionamento térmicos, os corpos-de-prova foram fixados com adesivo de cianoacrilato ao dispositivo de microtraçao e testados em uma máquina de ensaio universal (EMIC - DL-1000, Equipamentos e Sistemas Ltda., dos de Sao José dos Pinhais - o PR, Brasil) com velocidade constante sw 0,5mm/min. Os dados foram submetidos aos métodos estatísticos de ANOVA e Tukey. Os resultados indicaram que os valores médios de tensao de rupturas (MPa) de G1 (14,97+-4.68) nao diferiram estatisticamente (p<5porcento) de G2 (12.27+-4.72), porém houve diferença significante entre G1 e G3 (9.89+-4.16). Foi possível concluir que a termociclagem reduziu os valores de resistência adesiva significativamente quando os cors-de-prova foram submetidos a 12000 ciclos.