Physicochemical properties, cytotoxicity and bioactivity of a ready-to-use bioceramic repair material.

The aim of this study was to evaluate the physicochemical properties, cytotoxicity and bioactivity of a ready-to-use bioceramic material, Bio-C Repair (Angelus), in comparison with White MTA (Angelus) and Biodentine (Septodont). The physicochemical properties of setting time, radiopacity, pH, solubility, dimensional and volumetric changes were evaluated. Biocompatibility and bioactivity were assessed in Saos-2 osteoblast cell cultures by the MTT assay 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), Neutral Red (NR), Alizarin Red (ARS), and cell migration tests. Statistical analysis was performed by ANOVA, Tukey or Bonferroni tests (α = 0.05). Bio-C Repair had the longest setting time (p < 0.05), but radiopacity and solubility were accordance with the ISO 6876/2012 standards, besides linear expansion. Bio-C Repair and MTA had similar volumetric change (p > 0.05); lower than Biodentine (p < 0.05). All the materials evaluated had an alkaline pH. Bio-C Repair was cytocompatible and promoted mineralized nodule deposition in 21 days and cell migration in 3 days. In conclusion, Bio-C Repair had adequate radiopacity above 3mm Al, solubility less than 3%, dimensional expansion, and low volumetric change. In addition, Bio-C Repair promoted an alkaline pH and presented bioactivity and biocompatibility similar to MTA and Biodentine, showing potential for use as a repair material.

Physicochemical properties, cytotoxicity and bioactivity of a ready-to-use bioceramic repair material

Abstract The aim of this study was to evaluate the physicochemical properties, cytotoxicity and bioactivity of a ready-to-use bioceramic material, Bio-C Repair (Angelus), in comparison with White MTA (Angelus) and Biodentine (Septodont). The physicochemical properties of setting time, radiopacity, pH, solubility, dimensional and volumetric changes were evaluated. Biocompatibility and bioactivity were assessed in Saos-2 osteoblast cell cultures by the MTT assay 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), Neutral Red (NR), Alizarin Red (ARS), and cell migration tests. Statistical analysis was performed by ANOVA, Tukey or Bonferroni tests (α = 0.05). Bio-C Repair had the longest setting time (p < 0.05), but radiopacity and solubility were accordance with the ISO 6876/2012 standards, besides linear expansion. Bio-C Repair and MTA had similar volumetric change (p > 0.05); lower than Biodentine (p < 0.05). All the materials evaluated had an alkaline pH. Bio-C Repair was cytocompatible and promoted mineralized nodule deposition in 21 days and cell migration in 3 days. In conclusion, Bio-C Repair had adequate radiopacity above 3mm Al, solubility less than 3%, dimensional expansion, and low volumetric change. In addition, Bio-C Repair promoted an alkaline pH and presented bioactivity and biocompatibility similar to MTA and Biodentine, showing potential for use as a repair material.

Resumo O objetivo deste estudo foi avaliar as propriedades físico-químicas, citotoxicidade e bioatividade de um novo material biocerâmico pronto para uso, Bio-C Repair (Angelus), em comparação com MTA Branco (Angelus) e Biodentine (Septodont). Foram avaliadas as propriedades físico-químicas de tempo de presa, radiopacidade, pH, solubilidade, alterações dimensionais e volumétricas. A biocompatibilidade, bioatividade e capacidade de reparo foram avaliadas em culturas de células de osteoblastos Saos-2 pelo ensaio MTT brometo de 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazólio), vermelho neutro (NR), vermelho de alizarina ( ARS) e testes de migração celular. A análise estatística foi realizada pelos testes ANOVA, Tukey ou Bonferroni (α = 0,05). Bio-C Repair apresentou o maior tempo de presa (p < 0,05), mas radiopacidade e solubilidade de acordo com as normas ISO 6876/2012, além de expansão linear. Bio-C Repair e MTA tiveram variação volumétrica semelhante (p > 0,05), menor que Biodentine (p < 0,05). Todos os materiais avaliados apresentaram pH alcalino. Bio-C Repair foi citocompatível, além de promover deposição de nódulos mineralizados em 21 dias e migração celular em 3 dias. Em conclusão, o Bio-C Repair apresentou radiopacidade adequada acima de 3mmAl, solubilidade menor que 3%, expansão dimensional e baixa perda volumétrica.. Além disso, o Bio-C Repair promoveu um pH alcalino e apresentou bioatividade e biocompatibilidade semelhantes ao MTA e Biodentine, mostrando potencial para uso como material reparador

Fracture strength of teeth with coronal destruction after core build-up restoration with bulk fill materials.

OBJECTIVE: This study aimed to evaluate the fracture strength and failure modes of different core techniques in teeth with simulated coronal destruction. MATERIALS AND METHODS: Forty teeth were endodontically prepared and the specimens were divided into four experimental groups (n = 10) according to the core composition: Filtek One Bulk Fill-FOBF, Filtek Z350 XT-FZ350 (standard group), Filtek Bulk Fill Flow-FBFF, and LuxaCore Z-LCZ. CAD/CAM Monolithic zirconia crowns were obtained and cemented with RelyX U200. After storage in distilled water at 37°C for 48 h, the specimens were subjected to thermal cycling and to compressive strength mechanical tests. Statistical analyses (α = 0.05) were performed by non-parametric Kruskal-Wallis, Dunn post hoc, and Fisher's exact tests. RESULTS: No significant differences (p > 0.05) were observed among FOBF, FZ350, and FBFF (mean ranks = 20.30, 12.20, and 23.20, respectively). LCZ (mean rank = 26.30) produced results similar to those of FOBF and FBFF (p > 0.05) and higher than those of FZ350 (p = 0.042). The most frequent type of failure was irreparable, regardless of the experimental condition. The lowest percentages of reparable fractures were produced by FOBF group (10%). CONCLUSIONS: The use of bulk fill materials, including the "core-and-post" LCZ dual-cure resin composite, did not impair the fracture strength of endodontically treated teeth with coronal destruction. CLINICAL SIGNIFICANCE: Resin composite bulk fill materials that can be used as a core-and-post cementation in an only stage are interesting, since they enable clinicians to work with one only material, and avoid several materials interfaces, technical sensitivity, and longer chair-time due to multistep procedures.

One-step fiber post cementation and core build-up in endodontically treated tooth: A clinical case report.

OBJECTIVE: This clinical case report addresses the step-by-step of the application of a core-and-post system that uses a single resin composite material to fiber post cementation and core build-up in a maxillary left central incisor. CLINICAL CONSIDERATIONS: The literature reports several materials and methods for the restoration of endodontically treated teeth with coronal destruction that require an intra-radicular fiber post for the core build-up. The present case report describes a core-and-post or "monoblock" technique. A dual resin composite (Core-X Flow; Dentsply DeTrey) highly filled material and cement was used for luting the fiber post (Blue X-Post) and build-up the core structure in an easy application. CONCLUSIONS: The "core-and-post" technique that uses a single material system protocol minimizes the material interfaces, steps of procedures, and chair-time in comparison to conventional techniques. CLINICAL SIGNIFICANCE: The use of different materials for post cementation and core build-up requires more steps, which increases the chair-time and number of interfaces among the materials. Since the "monoblock" technique uses only one material, it can streamline the clinical procedures, thus, saving time and materials. Moreover, techniques based on core-and-post systems are easily applied, versatile, and esthetics, and can be applicable to posterior and anterior teeth.

Comparison of impression techniques and double pouring by dental cast's accuracy. Preliminary clinical-lab trial

Aim: This study compared impression techniques and double pouring by means of cast's accuracy. Methods: For each patient (n=10), impressions from right maxillary canine to first molar were made with acrylic resin trays and vinyl-polysiloxane using one single-step, and four two-steps techniques: relief with poly(vinyl chloride) film; tungsten-carbide bur/scalpel blade; small movements of the tray; non-relief. Total visible buccal surface area of crowns was measured three times using photographs from patients (Baseline) and casts. Mean area values (mm2) between Baseline and casts differences were analyzed by two-way repeated-measures ANOVA (α=.05; 1-ß=85%). Results: No significant differences were observed for Impression Techniques (P=.525), Double Pouring (P=.281), and their interaction (P=.809). Conclusion: All impression techniques and double pouring produced casts with similar accuracy

Effect of techniques, trays and materials on accuracy of impressions clinically made / Efeito de técnicas, moldeiras e materiais na exatidão de moldagens odontológicas

Abstract Introduction Making accurate and dimensionally stable impressions to duplicate oral conditions and tooth morphology is an essential step of prosthetic dentistry for fabricating well-fitted indirect restorations and, consequently, ensure the longevity and success of the treatment. Several authors describe pros and cons of different impression techniques, although there is no unanimity among them about the best one. Objective This study evaluated casts' accuracy made by different impression techniques, trays and materials. Material and method 10 patients were selected and 20 impressions from teeth #13 to #16 were performed using single-step (SS) and two-step techniques, made with metal stock and customized acrylic resin partial trays, vinyl polysiloxane and condensation silicone rubbers. Type IV gypsum was used to pour the casts. Three photographs of each patient (baseline), as their respective gypsum casts, were taken, measured in their interested buccal surface area. Comparisons of area values among experimental groups and baseline were performed. Data showed adherence to normal curve, being submitted to 3-way ANOVA/Bonferroni test (α=.05). Result Technique produced significant differences (P=0.02). SS technique was more accurate than BUR one (P=0.003; 95=1.22 to 5.98), but both resulted in similar casts to PVC, MOV and NR techniques, which were similar to each other (P>0.05). Conclusion SS technique showed the closest absolute values to baseline.

Resumo Introdução Realizar moldagens precisas e dimensionalmente estáveis que dupliquem a condição oral é um passo essencial para a confecção de restaurações indiretas de qualidade, garantindo seu sucesso e longevidade. Diversos estudos tem demonstrado os prós e contras de diferentes técnicas de moldagem, mas nenhum consenso da melhor técnica ainda foi descrito. Objetivo Este estudo avaliou a exatidão de modelos de gesso confeccionados por diferentes técnicas de moldagem, moldeiras e materiais. Material e método 10 pacientes foram selecionados e 20 moldes dos dentes #13 até #16 foram realizados utilizando técnicas simultânea (SS) e de dois passos, realizados com moldeiras parciais metálicas e individuais de resina acrílica, silicones de adição e condensação. Gesso tipo IV foi usados para os vazamentos. Três fotografias de cada paciente (baseline), assim como dos seus respectivos modelos de gesso foram realizadas e sua área foi então mensurada, na porção vestibular. Comparações de valores de área entre os grupos experimentais e o baseline foram performadas. Os dados mostraram aderência a curva normal, sendo submetidos ao teste 3-way ANOVA/Bonferroni (α=.05). Resultado As técnicas produziram diferenças significativas (P=0.02).Técnica simultânea foi mais precisa que a BUR (P=0.0003; 95=1,22 a 5.98), mas ambas resultaram em modelos similares àqueles feitos por meio das técnicas de PVC, MOV e sem NR, que foram similares entre si (P>0.05). Conclusão Técnica simultânea demonstrou valores absolutos similares àqueles demonstrados pelo baseline.

Fatigue behavior and surface characterization of a Y-TZP after laboratory grinding and regeneration firing.

This study evaluated the effect of grinding and regeneration firing on the flexural fatigue limit and surface characterization of Lava™ Y-TZP ceramic. Forty bar-shaped specimens with 20 × 4.0 × 1.2 mm constituted the as-sintered group (AS = control group), and 80 specimens with 20 × 4.0 × 1.5 mm were ground with cylindrical laboratory stone under water-cooling (WG) or in a dry condition (G) to reach 1.2 mm in thickness. Half of specimens were submitted to regeneration firing (1000 °C, 30 min), forming the groups AS/R, WG/R and G/R. Fatigue limit (500,000 cycles, 10 Hz) was determined by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey HSD tests (α = 0.05). The surface topography (n = 3) and fracture area (n = 3) were evaluated by SEM. Samples were also analyzed by Rietveld refinement from X-ray diffraction data. ANOVA revealed significant differences (P < .001) for grinding protocol, regeneration firing and their interaction. In the groups not submitted to regeneration firing, the mean flexural fatigue limit of WG was higher (P < .05) than that of G and AS, with no statistical difference between each other (P > .05). After regeneration firing the inequality WG>AS>G (P < .05) was observed. The regeneration firing increased the fatigue limit of AS group and decreased those of G and WG groups (P < .05). Grinding protocols created evident grooves on zirconia surface. Failures initiated on tensile side of all specimens. The percentages (wt%) of monoclinic phase before cyclic loading were: AS (7.4), AS/R (6.5), G (2.8), G/R (0.0), WG (4.4), WG/R (0.0); and after cyclic loading: AS (8.6), AS/R (1.2), G (2.4), G/R (5.7), WG (6.3), WG/R (0.0). Wet grinding did not compromise the fatigue limit of zirconia, increasing its mechanical strength. Regeneration firing reduced the fatigue limit of ground samples, despite reducing the amount of monoclinic phase in all experimental conditions.

Mandibular Reconstruction by Osteogenic Distraction Due to Two Different Injuries.

Varied factors, whether intrinsic or extrinsic, may lead to a decrease in the bone volume of the jaws. Trauma and pathology can be listed as examples of such factors. The aim of this study is to present the osteogenic distraction technique as alternative to augmentation of low mandibular bone volume caused by different etiologies. The first case reports a mandibular marginal resection of ameloblastoma and the second one reports a male patient presenting mandibular fracture sequelae. Both cases were treated according to the osteogenic distraction technique. Several factors have influence on the decision of treatment management of these conditions. Although autogenous bonegraft is considered criterion standard for alveolar reconstruction, its high rates of resorption and the morbidity associated to donor sites lead surgeons to seek for other surgical alternatives such as osteogenic distraction. Therefore, it also aims to expose the advantages and benefits of this technique as well as the satisfactory results achieved.

Custom Cast Ball Attachments Used on Outdated Implants to Restore a Maxillary Implant-Supported Overdenture.

The lack of compatible prosthetic components can be a complication during oral rehabilitation using outdated implants. The aim of the present clinical report was to describe an alternative technique for the fabrication of a maxillary implant-supported overdenture in a patient with 20-year-old dental implants using castable spherical patterns and ball attachments. The patient had been wearing a relined bar/clip overdenture in the mandible on 4 external-hexagon dental implants and a relined complete denture in the maxilla on 4 internal-hexagon implants due to abutment screw fracture inside of the implants, losing the attachment system. The remaining maxillary dental implants did not possess attachments compatible with current systems due to configuration changes by the manufacturer in the dental implant's platform and the components over time. Therefore, castable spherical patterns and cast ball attachments were used to fabricate a maxillary implant-supported overdenture. The mandible rehabilitation was performed using 4 osseointegrated dental implants with a fixed implant-supported prosthesis. The use of cast ball attachments on the maxillary dental implants avoided invasive procedures on the remaining implants. Considering the lack of available compatible prosthetic components for the osseointegrated implants, this technique was considered a viable and satisfactory treatment option.

Deformation of nickel-titanium closed coil springs: an in vitro study.

OBJECTIVE: The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs. METHODS: A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically. The values were compared by analysis of variance and Tukey's post-hoc test. RESULTS: Springs manufactured by Morelli had the same amount of deformation when they were activated up to 700% of Y activation; springs by Orthometric had the same amount of deformation up to 600-700% of Y; springs by Ormco had the same amount of deformation up to 700-800% of Y; and finally, the majority of springs by GAC had similar deformation up to 800%-1000% of activation. All springs tested could be activated up to 700% without rupture. CONCLUSIONS: Most subgroups were similarly deformed up to 700% of activation, without rupture of springs. Subgroups 4B, 4C, 4D and 4E showed the same amount of deformation up to 1000% of activation without any rupture at all.

Deformation of nickel-titanium closed coil springs: an in vitro study

ABSTRACT Objective: The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs. Methods: A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically. The values were compared by analysis of variance and Tukey's post-hoc test. Results: Springs manufactured by Morelli had the same amount of deformation when they were activated up to 700% of Y activation; springs by Orthometric had the same amount of deformation up to 600-700% of Y; springs by Ormco had the same amount of deformation up to 700-800% of Y; and finally, the majority of springs by GAC had similar deformation up to 800%-1000% of activation. All springs tested could be activated up to 700% without rupture. Conclusions: Most subgroups were similarly deformed up to 700% of activation, without rupture of springs. Subgroups 4B, 4C, 4D and 4E showed the same amount of deformation up to 1000% of activation without any rupture at all.

RESUMO Objetivo: o objetivo desse trabalho foi determinar a deformação em molas fechadas de níquel-titânio de quatro marcas comerciais. Métodos: cento e trinta molas foram divididas em treze subgrupos, de acordo com suas características e fabricantes (Morelli, Orthometric, Ormco e GAC), com ativação entre 100% e 1.000% do comprimento efetivo de níquel-titânio presente na mola (Y), a 37 °C. Dados de desativação foram coletados e a deformação foi obtida de forma gráfica. Os valores foram comparados por meio de análise de variância e teste post-hoc de Tukey. Resultados: as molas da Morelli apresentaram a mesma quantidade de deformação considerando-se 700% de ativação de Y; as molas da Orthometric tiveram a mesma quantidade de deformação até 600-700% de Y; as molas da Ormco tiveram a mesma quantidade de deformação até 700-800% de Y; e, por fim, a maioria das molas da GAC apresentou deformação semelhante até 800-1.000% de ativação. Todas as molas testadas puderam ser ativadas até 700% sem ruptura. Conclusões: a maioria dos subgrupos se deformou de maneira semelhante até 700% de ativação, sem ruptura das molas. Os subgrupos 4B, 4C, 4D e 4E demonstraram a mesma quantidade de deformação até 1.000% de ativação, sem nenhuma ruptura.

Accuracy of Gypsum Casts after Different Impression Techniques and Double Pouring.

This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS) material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1) one-step; two-step relief with: (2) PVC film; (3) slow-speed tungsten carbide bur and scalpel blade, (4) small movements of the tray and (5) without relief-negative control. The impressions were disinfected with 0.5% sodium hypochlorite for 10 minutes and stored during 110 and 230 minutes for the first and second pouring, respectively, with type IV gypsum. Three intra-oral lateral photographs of each patient were taken using a tripod and a customized radiographic positioner. The images were imported into ImageJ software and the total area of the buccal surface from teeth #13 to #16 was measured. A 4.0% coefficient of variance was criterion for using these measurements as Baseline values. The casts were photographed and analyzed using the same standardization for the clinical images. The area (mm2) obtained from the difference between the measurements of each gypsum cast and the Baseline value of the respective patient were calculated and analyzed by repeated-measures two way-ANOVA and Mauchly's Sphericity test (α = 0.05). No significant effect was observed for Impression technique (P = 0.23), Second pouring (P = 0.99) and their interaction (P = 0.25). The impression techniques and double pouring did not influence the accuracy of the gypsum casts.

Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic.

This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.

Evaluation of Three Different Osteosynthesis Methods for Mandibular Angle Fractures: Vertical Load Test.

The aim of this study was to evaluate the mechanical behavior of different rigid fixation methods in mandible angle fractures. Three different plates were tested: one 4-hole grid miniplate, one 8-hole curved grid miniplate, and one 4-hole straight miniplate.For the loading tests, 30 polyurethane hemimandibles sectioned at the angle area to simulate a simple angle fracture were used: 10 hemimandibles for each group. The mechanical evaluation revealed that the straight plate positioned at the tension zone presented the best results in supporting vertical loading in the predefined displacement moments of 1, 3, and 5 mm. Regarding the grid plates, there was no statistically significant difference between the smaller and the larger plate.According to this sample, the straight plate positioned in the tension zone presented better results than the other 2 different grid plates positioned at the neutral zone.

Effect of Grinding and Resintering on the Fatigue Limit and Surface Characterization of a Y-TZP Ceramic

Abstract This study evaluated the effect of grinding protocols and resintering on flexural fatigue limit and surface characterization of LavaTM Y-TZP. Bar-shaped specimens (20×4.0×1.2 mm, n=40; 20×4.0×1.5 mm, n=80) were obtained. Half of the thinner specimens (1.2 mm) constituted the as-sintered group (AS), while the thicker ones (1.5 mm) were ground with diamond burs under irrigation (WG) or not (G). The other half of thinner and half of ground specimens were resintered (1000 ºC, 30 min), forming the groups ASR, WGR and GR. Fatigue limit (500,000 cycles, 10 Hz) was evaluated by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey's test (α=0.05). Surface topography (n=3) and fracture area (n=3) were evaluated by SEM. X-ray diffraction data (n=1) was analyzed by Rietveld refinement. ANOVA revealed significant differences (p<0.001) for the grinding protocol, resintering and their interaction. Grinding increased the fatigue limit of non-resintered groups. There was no significant difference among the resintered groups. Resintering significantly increased the fatigue limit of the AS group only. Both protocols created evident grooves on zirconia surface. The failures initiated at the tensile side of all specimens. The percentages (wt%) of monoclinic phase were AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) before, and AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) after cyclic loading. Grinding increased the fatigue limit of non-resintered Y-TZP and formed evident grooves on its surface. Resintering provided significant increase in the fatigue limit of as-sintered specimens. In general, grinding and resintering decreased or zeroed the monoclinic phase.

Resumo Este estudo avaliou o efeito de protocolos de desgaste e ressinterização no limite de fadiga flexural e na caracterização da superfície da zircônia LavaTM. Corpos-de-prova em forma de barra (20×4,0×1,2 mm, n=40; 20×4,0×1,5 mm, n=80) foram obtidos. Metade das barras com menor altura (1,2 mm) constituiu o grupo controle (AS), enquanto as de maior altura (1,5 mm) foram desgastadas com fresas diamantadas com (WG) ou sem (G) irrigação. A outra metade dos corpos-de-prova de menor altura e metade dos desgastados foram ressinterizadas (1000 °C, 30 min), obtendo-se os grupos ASR, WGR e GR. O limite de fadiga (500.000 ciclos, 10 Hz) foi avaliado pelo método de escada em dispositivo de flexão em 4 pontos. Os dados foram analisados pelos testes ANOVA a dois fatores e Tukey (α=0,05). A topografia de superfície (n=3) e área de fratura (n=3) foram avaliadas por MEV. Os dados de difração de raios-X (n=1) foram analisados pelo refinamento de Rietveld. ANOVA revelou diferenças significantes (p<0,001) para desgaste, ressinterização e interação entre os fatores. O desgaste aumentou o limite de fadiga para os grupos não ressinterizados. Não houve diferença significante entre os grupos ressinterizados. A ressinterização aumentou o limite de fadiga somente para o grupo AS. Ambos os protocolos criaram riscos evidentes na superfície da zircônia. As falhas iniciaram sempre no lado de tração. A porcentagem de fase monoclínica foi: AS (8.6), ASR (1.2), G (1.8), GR (0.0), WG (8.2), WGR (0.0) antes e AS (7.4), ASR (6.5), G (3.2), GR (0.2), WG (4.6), WGR (1.1) após a ciclagem. O desgaste aumentou o limite de fadiga da zircônia não ressinterizada e formou ranhuras evidentes na sua superfície. A ressinterização promoveu aumento significativo no limite de fadiga somente para o grupo controle. Em geral, o desgaste e a ressinterização diminuíram ou anularam o conteúdo de fase monoclínica.

Influence of Sealing of the Screw Access Hole on the Fracture Resistance of Implant-Supported Restorations.

The purpose of this study was to assess the influence of sealing of the screw access hole (SAH) on the fracture resistance of metal-ceramic implant-supported restorations. UCLA abutments were used to make 30 implant-retained mandibular molar restorations and divide equally into three groups: Group SRS: screw-retained restorations with SAH sealed; Group SRNS: screw-retained restorations with SAH not sealed; Group CR: cement-retained restorations. The following protocol was adopted to restore the SAH: the ceramic surface of the SAH was air-abraded with aluminum oxide; etched with 10% hydrofluoric acid; a silane coupling agent and a bonding agent were applied; cotton pellets were used as filling material and P-60 resin composite as restoring material. The cement-retained restorations were cemented with Rely-X U100. A metal rod with a spherical tip of 6.0 mm diameter was used to apply a vertical static load, simultaneously on the buccal and lingual incline cusps, at a crosshead speed of 0.5 mm/min until the fracture of the specimens. Data were analyzed using one-way ANOVA and Dunnet test (p<0.05) for multiples comparisons. The mode of failure was evaluated by a scanning electron microscopy (SEM). No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with CR group. Therefore, it was shown that SAH sealing did not influence the fracture resistance of the screw-retained restorations.

Influence of Sealing of the Screw Access Hole on the Fracture Resistance of Implant-Supported Restorations

Abstract The purpose of this study was to assess the influence of sealing of the screw access hole (SAH) on the fracture resistance of metal-ceramic implant-supported restorations. UCLA abutments were used to make 30 implant-retained mandibular molar restorations and divide equally into three groups: Group SRS: screw-retained restorations with SAH sealed; Group SRNS: screw-retained restorations with SAH not sealed; Group CR: cement-retained restorations. The following protocol was adopted to restore the SAH: the ceramic surface of the SAH was air-abraded with aluminum oxide; etched with 10% hydrofluoric acid; a silane coupling agent and a bonding agent were applied; cotton pellets were used as filling material and P-60 resin composite as restoring material. The cement-retained restorations were cemented with Rely-X U100. A metal rod with a spherical tip of 6.0 mm diameter was used to apply a vertical static load, simultaneously on the buccal and lingual incline cusps, at a crosshead speed of 0.5 mm/min until the fracture of the specimens. Data were analyzed using one-way ANOVA and Dunnet test (p<0.05) for multiples comparisons. The mode of failure was evaluated by a scanning electron microscopy (SEM). No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with CR group. Therefore, it was shown that SAH sealing did not influence the fracture resistance of the screw-retained restorations.

Resumo O objetivo deste estudo foi avaliar a influência do selamento do orifício de acesso ao parafuso (OAP) na resistência à fratura de coroas metalocerâmicas implantossuportadas aparafusadas. Pilares UCLA foram utilizados para fazer 30 molares inferiores implantossuportados e divididos igualmente em três grupos: Grupo AS: coroas aparafusadas com o OAP selado; Grupo ANS: coroas aparafusadas com o OAP não selado; Grupo CC: coroas cimentadas. O seguinte protocolo foi utilizado para selar o OAP: a superfície de cerâmica do OAP foi jateada com óxido de alumínio; condicionada com ácido fluorídrico a 10%; um agente silano e um adesivo dentinário foram aplicados; bolinhas de algodão foram utilizadas como material de preenchimento e a resina composta P-60 como material de restauração. As coroas cimentadas foram cimentadas com Rely-X U100. Uma haste de metal com uma ponta esférica de 6.0 mm de diâmetro foi usada para aplicar uma carga estática vertical, simultaneamente nas vertentes triturantes das cúspides linguais e vestibulares, com 0,5 mm/min velocidade do atuador até a fratura das coroas. Os dados foram analisados através de ANOVA um fator e teste de Dunnett (p<0,05) para as comparações múltiplas. O modo de falha foi avaliado por um microscópio eletrônico de varredura (MEV). Não houve diferença significativa entre restaurações aparafusadas. Os maiores valores médios de resistência à fratura foram observados com o Grupo CC. Portanto, observou-se que o selamento do OAP não influenciou a resistência à fratura das coroas aparafusadas.

Fracture resistance of simulated immature teeth after different intra-radicular treatments.

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Sistema Cone Morse e utilização de pilares com plataforma switching / Morse Taper System and platform switching abutment application

Os implantes cone morse associados a pilares com plataforma switching têm proporcionado resultados promissores com relação à estabilidade dos tecidos peri-implantares. Isso se deve ao perfil cônico do componente protético, à íntima adaptação na interface implante/pilar e ao menor acúmulo de biofilme bacteriano. Para isso, deve-se levar em consideração o posicionamento infraósseo do implante. Essa configuração implante/pilar possui resistência à fratura superior em relação aos sistemas convencionais e, além disso, devido à manutenção da crista óssea e da diversidade de pilares e componentes protéticos, possibilita reabilitações orais estéticas e biocompatíveis.

Morse taper implants associated with platform switching abutments have provided promising results with respect to the stability of peri-implant tissues. This is due to the conical profile of the abutment, the intimate adaptation at the implant/abutment interface, and to the lower accumulation of bacterial biofilm. For this, it has been proposed the insertion of the implants below the crestal bone level. This implant/ abutment configuration presents higher fracture strength compared to the conventional systems and, in addition, because of the maintenance of crestal bone and the diversity of abutments and prosthetic components, provides aesthetic and biocompatible oral rehabilitations.

Fracture Resistance of Simulated Immature Teeth after Different Intra-radicular Treatments

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

O objetivo deste estudo foi avaliar a resistência à fratura de dentes com rizogênese incompleta simulada após diferentes tratamentos intra-radiculares. A rizogênese incompleta foi simulada pelo seccionamento das coroas e raízes de incisivos bovinos. O preparo e alargamento do canal radicular foram realizados utilizando uma broca no sentido coroa-ápice e ápice-coroa. As amostras foram distribuídas (n=10) em cinco grupos: controle positivo (PoC) - sem preparo do canal radicular e sem obturação; controle negativo (NeC) - os dentes foram seccionados e os canais radiculares foram preparados; pino anatômico direto Reforpost #2 (RaP) - pino de fibra de vidro principal + resina composta; pino de fibra de vidro com dupla conicidade (ExP) - pino de fibra de vidro Exacto #3; e pino de fibra de vidro Reforpost #2 + pinos de fibra de vidro acessórios Reforpin (RrP). Nos grupos RaP, ExP e RrP foram realizados plugs apicais de MTA Angelus com 4,0 mm. As amostras foram incluídas em cilindros com resina de poliestireno e o ligamento periodontal foi simulado com material de moldagem à base de poliéter. As amostras foram submetidas ao teste de resistência à fratura, por meio de força compressiva (0,5 mm/min a 135º em relação ao longo eixo do dente) em uma máquina de ensaios mecânicos MTS 810. Os dados foram submetidos à ANOVA a um critério e aos testes para comparações múltiplas Dunnett C ou Tukey HSD (α=0,05). Os grupos controle (PoC e NeC) apresentaram resistência à fratura inferior aos grupos experimentais, sendo o menor valor médio produzido por NeC. ExP produziu os maiores valores de resistência à fratura entre os grupos experimentais. Os procedimentos de preparo e alargamento produziram efeitos prejudiciais na resistência à fratura de dentes bovinos. A utilização de pinos de fibra de vidro intra-radiculares aumentou significativamente a resistência à fratura de dentes com rizogênese incompleta simulada.