Reparative regeneration by substitution of bone tissue defects with bioglass, using regeneration technologies / Regeneración reparadora mediante sustitución de defectos del tejido óseo por biovidrio, utilizando tecnologías de regeneración

SUMMARY: Bioactive glass (BG) induces osteogenesis of damaged bone, causing excessive bone formation. This study included a morphological and morphometrical data of the bone tissue regeneration by filling bone defects with BG with autologous native platelet rich plasma (PRP) or fibrin (PRF) and aspirate of bone marrow (ABM). The parameters of newly formed bone in rabbits bone defect were analyzed and compared with terms 4th and 12th week. The groups with ABM-BG, PRF-BG and PRP-BG have shown common tendency: development of newly formed bone tissue, the external contour of the bone has been enlarged; an additional trabecular bone has been formed under the cortical layer, which has often been limited by a solid compact bone from the bone marrow. The induced osteogenesis resulted in the appearance of a significant amount of bone tissue exceeding the original size of the defect. Increased density of the newly formed tissue at the defect level relative to ABM-BG was detected in the PRF-BG group at 12 weeks and PRP-BG at 4 and 12 weeks (p<0.05). In this case, the bone thickness in the substituted defect was greater in the ABM-BG group. The number of newly formed bone tissue in the ABM-BG group at 4 weeks also exceeded the value of the BG group, but the density of such bone did not differ between the groups. That is, ABM-BG stimulated greater trabecular bone formation and fibrous reticular tissue was located in the lacunae between trabeculae. These results indicate that the additional use of tissue technology (ABM, platelet plasma) facilitated osteogenesis, and the newly formed bone tissue was tightly coupled and remodeled to the cortical bone layer in the form of compact bone tissue. PRP, to a greater extent than ABM, promoted the formation of compact bone tissue.

RESUMEN: El vidrio bioactivo (VB) induce la osteogénesis del hueso dañado, provocando una formación excesiva de hueso. Este estudio incluyó datos morfológicos y morfométricos de la regeneración del tejido óseo mediante el llenado de defectos óseos con VB con plasma rico en plaquetas (PRP) nativo autólogo o fibrina (PRF) y aspirado de médula ósea (AMO). Se analizaron los parámetros de hueso recién formado en el defecto óseo de conejos y se compararon a las 4 y 12 semanas. Se observó una tendencia similar en los grupos con AMO-VB, PRF-VB y PRP-VB: el desarrollo de tejido óseo recién formado, aumentó el contorno externo del hueso; formación de un hueso trabecular adicional debajo de la capa cortical, que a menudo ha estado limitada por un hueso sólido compacto de la médula ósea. La osteogénesis inducida dio como resultado la aparición de una cantidad significativa de tejido óseo que excedía el tamaño original del defecto. Se detectó un aumento de la densidad del tejido recién formado a nivel del defecto en relación con AMO-VB en el grupo PRF-VB a las 12 semanas y PRP-VB a las 4 y 12 semanas (p <0,05). En este caso, el grosor óseo en el defecto sustituido fue mayor en el grupo AMO-VB. El número de tejido óseo recién formado en el grupo AMO- VB a las 4 semanas también excedió el valor del grupo VB, pero la densidad de dicho hueso no cambió entre los grupos. Es decir, AMO-VB estimuló una mayor formación de hueso trabecular y se localizó en el tejido reticular fibroso en las lagunas entre trabéculas. Estos resultados indican que el uso adicional de tecnología de tejidos (AMO, plasma plaquetario) facilitó la osteogénesis, y el tejido óseo recién formado se acopló y remodeló estrechamente a la capa de hueso cortical en forma de tejido óseo compacto. El PRP, en mayor medida que el AMO, promovió la formación de tejido óseo compacto.

Microstructural and mechanical analysis of two CAD-CAM lithium disilicate glass-reinforced ceramics

Abstract The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.

Experimental gel containing bioactive glass-ceramic to minimize the pulp damage caused by dental bleaching in rats

Abstract Objectives This study evaluated if the use of a bioactive glass-ceramic-based gel, named Biosilicate (BS), before, after or mixed with bleaching gel, could influence the inflammation of the dental pulp tissue of rats' molars undergoing dental bleaching with hydrogen peroxide (H2O2). Methodology The upper molars of Wistar rats (Rattus norvegicus, albinus) were divided into Ble: bleached (35% H2O2, 30-min); Ble-BS: bleached and followed by BS-based gel application (20 min); BS-Ble: BS-based gel application and then bleaching; BS/7d-Ble: BS-based gel applications for 7 days and then bleaching; Ble+BS: blend of H2O2 with BS-based gel (1:1, 30-min); and control: placebo gel. After 2 and 30 days (n=10), the rats were euthanized for histological evaluation. The Kruskal-Wallis and Dunn statistical tests were performed (P<0.05). Results At 2 days, the Ble and Ble-BS groups had significant alterations in the pulp tissue, with an area of necrosis. The groups with the application of BS-based gel before H2O2 had moderate inflammation and partial disorganization in the occlusal third of the coronary pulp and were significantly different from the Ble in the middle and cervical thirds (P<0.05). The most favorable results were observed in the Ble+BS, which was similar to the control in all thirds of the coronary pulp (P>0.05). At 30 days, the pulp tissue was organized and the bleached groups presented tertiary dentin deposition. The Ble group had the highest deposition of tertiary dentin, followed by the Ble-BS, and both were different from control (P<0.05). Conclusion A single BS-based gel application beforehand or BS-based gel blended with a bleaching gel minimize the pulp damage induced by dental bleaching.

Reabilitação estética e funcional de dentes decíduos anteriores com pino de fibra de vidro e matriz anatômica de celulóide: uma revisão da literatura / Aesthetic and functional rehabilitation of anterior deciduous teeth with fiberglass post and anatomic celluloid matrix: a literature review

Objetivo: expor, por meio de uma revisão de literatura, uma discussão sobre os benefícios do uso do pino de fibra de vidro e matriz de celulóide na reabilitação oral de crianças, como suas possibilidades e técnicas mais adequadas para o tratamento de pacientes com amplas destruições coronárias em dentes decíduos. A cárie dentária é uma das doenças crônicas mais comum na infância, se o diagnóstico adequado não for realizado em estágios iniciais podem gerar danos irreparáveis, levando a perda dentária. Atualmente, se reconhece a importância de se preservar os dentes decíduos até o período correto de sua esfoliação, dessa forma, dependendo da quantidade de remanescente dental, o tratamento reabilitador estético em dentes decíduos, pode necessitar de um retentor intra-canal. Considerações finais: embora exista um número considerável de alternativas reabilitadoras, a mais utilizada é o de pino de fibra de vidro com matriz anatômica de celuloide, por ser de fácil execução, baixo custo e não necessitar de etapa laboratorial. Porém, a escolha do tratamento restaurador deve ser feita de comum acordo com os pais e um grande grau de colaboração dos pacientes.(AU)

Objective: To present, through a literature review, a discussion about the benefits of using fiberglass posts and celluloid matrix in the oral rehabilitation of children and the most appropriate potentials and techniques for the treatment of patients with extensive crown destruction in deciduous teeth. Dental caries is one of the most common chronic diseases in children and, if not diagnosed properly in its early stages, it may cause irreparable damages that lead to tooth loss. Currently, the importance of preserving deciduous teeth up to the correct period of exfoliation is established. Therefore, depending on the amount of remaining teeth, the aesthetic rehabilitation in deciduous teeth may require an intracanal retainer. Final considerations: Although there is a considerable number of rehabilitation alternatives, the most used is the fiberglass post with anatomic celluloid matrix, because it is easy to perform, presents low cost, and does not require a laboratory step. However, the treatment should be selected in agreement with the parents and significant cooperation from the patients.(AU)

Reabilitação em dentes anteriores com pinos de fibra de vidro e coroas metal free: relato de caso / Rehabilitation on previous teeth with glass fiber pins and metal free crowns: case report

Objetivo: descrever uma reabilitação em incisivos superiores por meio da associação de coroas totais de cerâmica e retentor intrarradicular de fibra de vidro. Caso clínico: paciente P. C. G., gênero masculino, de 49 anos de idade, leucoderma, insatisfeito com a estética dos dentes anteriores devido a traumatismo dentário e fraturas recorrentes das restaurações. Após a realização de anamnese, exames clínico e radiográfico, contataram-se restaurações de resina composta insatisfatórias nos dentes anteriores, grandes diastemas entre os dentes e leve inflamação gengival. Para o plano de tratamento, optou-se por realização do tratamento endodôntico dos elementos 12 e 22, pino de fibra de vidro no dente 21, e coroas totais de dissilicato de lítio em todos os incisivos superiores. Considerações finais: com a finalização do tratamento e o retorno do paciente à clínica após seis meses, pode-se observar um tecido gengival sadio e o paciente muito satisfeito com os resultados obtidos. (AU)

Objective: to describe a rehabilitation in upper incisors through the association of total ceramic crowns and intra-radicular fiberglass retainer. Clinical case: patient P. C. G. male sex, 49 years old, leucoderma, dissatisfied with the aesthetics of the anterior teeth due to dental traumatism and recurrent fractures of the restorations. After anamnesis, clinical and radiographic examination, unsatisfactory composite resin restorations on anterior teeth, large diastema between teeth and mild gingival inflammation were contacted. For the treatment plan, we chose to perform endodontic treatment of elements 12 and 22, glass fiber pin on tooth 21, and total crowns of lithium disilicate on all upper incisors. Final considerations: with the completion of the treatment and return of the patient to the clinic after six months, a healthy gingival tissue can be observed and the patient very satisfied with the results obtained. (AU)

Bond strength values of fiberglass post to flared root canals reinforced with different materials

Abstract The aim of this study was to compare in vitro the bond strength (BS) between fiberglass posts and flared root canals reinforced with different materials. The roots of 48 premolars were endodontically treated. After one week, the root canals were prepared to simulate an oversized root canal, except for the positive control group (PCG), which was cemented with a prefabricated fiber post (PFP) compatible with the root canal size, simulating an ideal adaptation. The other samples (n=8/group) were used to test alternative restorative techniques for filling root canals: negative control group (NCG [PFP with a smaller diameter than of the root canal]), composite resin group - CRG, bulkfill group - BFG, self-adhesive cement group - SAG, and glass ionomer group - GIG. The posts were cemented and after 1 week, each root was sectioned transversely into six 1-mm thick discs and the push-out test was done to evaluate the BS. Data were analyzed by two-way repeated measures ANOVA and Tukey's tests (α=0.05). The highest BS value was observed for PCG. The NCG and the GIG groups showed the lowest BS values. Root reinforcement with conventional and bulk-fill composite resins showed the highest BS values; however, the bulk-fill resin was the only treatment able to maintain high BS values in all regions of the root canal. The self-adhesive cement showed intermediate results between CRG and GIG. Root reinforcement with bulk-fill composite resin is an effective option for flared root canals before cementation of a prefabricated fiber post.

Can low-fusing glass application affect the marginal misfit and bond strength of Y-TZP crowns?

Abstract To evaluate the effect of different surface treatments on the marginal misfit and retentive strength between Y-TZP crowns and an epoxy resin. Forty (40) epoxy resin (G10) abutments (height: 5mm, conicity: 60, finish line: large chamfer) with equal dimensions were milled and included in polyurethane to simulate the periodontal ligament. Next, 40 Y-TZP crowns (thickness: 1mm) were milled (Cerec in Lab) and randomly divided into four groups (n=10) according to the surface treatment: GS(glaze spray), GP(glaze powder/liquid), P(zirconia primer) and RS(tribochemical silica coating). The conditioned surfaces were cemented with dual self-adhesive cement, light cured and submitted to thermomechanical cycling (2x106, 100N, 4Hz, 5°/55°C). Marginal misfit was analyzed by a stereomicroscope and SEM. Retentive strength test was performed (1mm/min) until crown debonding. Glaze layer thickness was also performed to GS and GP groups. Marginal misfit data were analyzed by Kruskal Wallis and Dunn tests; one-way ANOVA and Tukey (5%) analyzed the tensile strength data. The marginal misfit of the GS (48.6±19.9μm) and GP (65.4±42.5μm) were statistically lower than the RS (96±62.9μm) and P (156±113.3μm) (p=0.001). The retentive strength of the GP (470.5±104.1N) and GS (416.8±170.2N) were similar to the P (342.1±109.7N), but statistically higher than those of the RS (208.9±110N). The GS and GP glaze layer was 11.64μm and 9.73μm respectively. Thus, glaze application promoted lower marginal discrepancy and higher retentive strength values than conventional techniques.

Influence of preheating and post-curing on a novel fiber-reinforced composite post material

Abstract The aim of this study was to investigate the influence of preheating and post-curing methods on diametral tensile strength (DTS), flexural strength (FS), knoop microhardness (KHN), and degree of conversion (DC) of an experimental fiber-reinforced composite (FRC). Specimens (30 wt% of 3-mm-short E-glass fiber, 22.5 wt% of methacrylated-based resin and 47.5 wt% of filler particles) were subjected to: P - photocuring at 1500 mW/cm2 for 40 s (control); P/M - photocuring and microwave post-curing (540W/5 minutes); P/A - photocuring and autoclave post-curing (120°C/15 minutes); PH-P - preheating (60°C) and photocuring; PH-P/M - preheating, photocuring and microwave post-curing; and PH-P/A - preheating, photocuring and autoclave post-curing. Specimens for DTS (Ø 3 x 6 mm) and FS (25 x 2 x 2 mm) were tested at Instron 5965. KHN employed a 50g load for 30s. DC was measured using FTIR spectroscopy. Statistical analysis employed: factorial analysis, normality test, one-way ANOVA and Tukey's HSD test, independent T-test and the Dunnett test. Interaction between factors was not significant (P>0.05). Preheating promoted significantly higher values of FS and KHN (p = 0.0001). Post-curing promoted significantly higher values for KHN (p = 0.0001). For DTS (p = 0.066) and DC (p= 0.724) no statistical difference was found between groups. SEM images showed that preheating promoted better interaction between glass fibers and resin matrix. Preheating increased FS, KHN and DTS, and post-curing increased KHN. DC was not affected by both methods. Preheating and post-curing methods can be used to improve some mechanical properties of FRCs' but degree of conversion remains unaffected.

Light curing resin cements containing iodonium salts promote suitable apical bonding of posts to radicular dentin

Abstract The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II - dual-cured and superior to VARIOLINK II - light-cured (except for EDMAB - 1DPI in the medium third and DMAEMA - 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

Bioactive glass added to autogenous bone graft in maxillary sinus augmentation: a prospective histomorphometric, immunohistochemical, and bone graft resorption assessment

Abstract Objective The aim of this study was to compare the bone resorption rate, histomorphometry and immunohistochemical findings of bioactive glass (Biogran; Biomet, Warsaw, IN, USA) mixed with autogenous bone grafts (1:1) and autogenous bone graft isolate in maxillary sinus elevation surgery. Material and Methods A total of 9 maxillary sinuses were grafted with Biogran with autogenous bone graft (group 1) and 12 were mixed with autogenous bone graft (group 2). Postoperative cone beam computed tomography (CBCT) was used to measure the initial graft volume after 15 days (T1), and 6 months later, another CBCT scan was performed to evaluate the final graft volume (T2) and determine the graft resorption rate. The resorption outcomes were 37.9%±18.9% in group 1 and 45.7%±18.5% in group 2 (P=0.82). After 6 months, biopsies were obtained concurrent with the placement of dental implants; these implants were subjected to histomorphometric analysis and immunohistochemical analysis for tartrate-resistant acid phosphatase (TRAP). Results The average bone formation in group 1 was 36.6%±12.9 in the pristine bone region, 33.2%±13.3 in the intermediate region, and 45.8%±13.8 in the apical region; in group 2, the values were 34.4%±14.4, 35.0%±13.9, and 42.0%±16.6 of new bone formation in the pristine bone, intermediate, and apical regions, respectively. Immunostaining for TRAP showed poor clastic activity in both groups, which can indicate that those were in the remodeling phase. Conclusions The similarity between the groups in the formation and maintenance of the graft volume after 6 months suggests that the bioactive glass mixed with autogenous bone (1:1) can be used safely as a bone substitute for the maxillary sinus lift.

Trends in restorative composites research: what is in the future?

Abstract Clinical trials have identified secondary caries and bulk fracture as the main causes for composite restoration failure. As a measure to avoid frequent reinterventions for restoration replacement, composites with some sort of defense mechanism against biofilm formation and demineralization, as well as materials with lower susceptibility to crack propagation are necessary. Also, the restorative procedure with composites are very time-consuming and technically demanding, particularly concerning the application of the adhesive system. Therefore, together with bulk-fill composites, self-adhesive restorative composites could reduce operator error and chairside time. This literature review describes the current stage of development of remineralizing, antibacterial and self-healing composites. Also, an overview of the research on fiber-reinforced composites and self-adhesive composites, both introduced for clinical use in recent years, is presented.

Growth, viability and architecture of biofilms of Listeria monocytogenes formed on abiotic surfaces

Abstract The pathogenic bacterium Listeria monocytogenes can persist in food processing plants for many years, even when appropriate hygienic measures are in place, with potential for contaminating ready-to-eat products and, its ability to form biofilms on abiotic surfaces certainly contributes for the environmental persistence. In this research, L. monocytogenes was grown in biofilms up 8 days attached to stainless steel and glass surfaces, contributing for advancing the knowledge on architecture of mature biofilms, since many literature studies carried out on this topic considered only early stages of cell adhesion. In this study, biofilm populations of two strains of L. monocytogenes (serotypes 1/2a and 4b) on stainless steel coupons and glass were examined using regular fluorescence microscopy, confocal laser scanning microscopy and classic culture method. The biofilms formed were not very dense and microscopic observations revealed uneven biofilm structures, with presence of exopolymeric matrix surrounding single cells, small aggregates and microcolonies, in a honeycomb-like arrangement. Moreover, planktonic population of L. monocytogenes (present in broth media covering the abiotic surface) remained stable throughout the incubation time, which indicates an efficient dispersal mechanism, since the culture medium was replaced daily. In conclusion, even if these strains of L. monocytogenes were not able to form thick multilayer biofilms, it was noticeable their high persistence on abiotic surfaces, reinforcing the need to focus on measures to avoid biofilm formation, instead of trying to eradicate mature biofilms.

Randomized clinical trial of the effect of NovaMin and CPP-ACPF in combination with dental bleaching

Abstract Objective This randomized, controlled, double-blind clinical study evaluated the effect of calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) on the prevention of post-operative sensitivity and on the effects of clinical bleaching treatment. Material and Methods Sixty volunteers were selected according to inclusion and exclusion criteria and were randomly assigned into three groups (n=20): CG (control group) patients, who were treated with 35% hydrogen peroxide; NOVAG (NovaMin group) patients, who were treated with 35% hydrogen peroxide followed by the application of NovaMin; and CPPG (CPP group) patients, who were treated with 35% hydrogen peroxide followed by the application of CPP-ACPF. Both bioactive agents were applied for five minutes. An evaporative stimulus associated with a modified visual scale was used to analyze sensitivity 24 hours after each bleaching session. The color evaluation was performed on the maxillary central incisors using a spectrophotometer. Associations between the intervention group, bleaching session, and reported sensitivity were tested using Chi-square partitioning. Results Color change values (ΔE) were analyzed using analysis of variance (ANOVA). The significance level used for both tests was 5%. In the intragroup assessment, the Friedman test showed that only the CPP-ACPF group showed no statistically significant difference (p<0.05) between baseline and first bleaching session. In the intergroup assessment, the Kruskal-Wallis test showed that the CPPG had less postoperative sensitivity after the first session, when compared to the other groups (p<0.05). Color change analysis (ΔE) showed a significant difference between the means obtained in the different bleaching sessions in all groups (p<0.05). Conclusions This study showed that the combination of CPP-ACPF with 35% hydrogen peroxide significantly reduced post-operative sensitivity in the first session, compared with the other evaluated treatments. The association of CPP-ACPF and NovaMin did not affect the color change induced by tooth bleaching.

Behavior study of the doped castor bean polymer rod with bioactive glass and hidroxyapatite in mice femur medullary canal

Abstract Purpose To evaluate the polymer doped rods behavior with bioactive glass and hydroxyapatite for possible application as a fracture fixing method. Methods Twenty eight Rattus norvegicus Wistar underwent bone defect for access to the femoral medullary canal and distributed into three experimental groups: group A - doped castor bean polymer with bioactive glass; group B - castor bean polymer and; group C - castor bean polymer doped with bioactive glass and hydroxyapatite. After 15 and 60 evaluation days, the femurs were removed and sent for histology and scanning electron microscopy. Results Initially mild and moderate inflammatory infiltrate is observed that decreases as time goes by, and the presence of connective tissue capsule around the graft in all groups. Regarding the biomaterials resorption little was observed. The implanted rods did not favor the osteoconductive process in the femoral medullary canal which was observed only in the C15 group. Conclusions The association of castor bean polymer, bioactive glass and hydroxyapatite was biocompatible and osteointegrable. The osteoconductive only occurred in the presence of hydroxyapatite and bioactive glass (C15 Group) and little biodegradation was observed.

Clinical performance and failure modes of pulpless teeth restored with posts: a systematic review

Abstract The aim of this systematic review was to compare the clinical performance and failure modes of teeth restored with intra-radicular retainers. A search was performed on PubMed/Medline, Central and ClinicalTrials databases for randomized clinical trials comparing clinical behavior and failures of at least two types of retainers. From 341 detected papers, 16 were selected for full-text analysis, of which 9 met the eligibility criteria. A manual search added 2 more studies, totalizing 11 studies that were included in this review. Evaluated retainers were fiber (prefabricated and customized) and metal (prefabricated and cast) posts, and follow-up ranged from 6 months to 10 years. Most studies showed good clinical behavior for evaluated intra-radicular retainers. Reported survival rates varied from 71 to 100% for fiber posts and 50 to 97.1% for metal posts. Studies found no difference in the survival among different metal posts and most studies found no difference between fiber and metal posts. Two studies also showed that remaining dentine height, number of walls and ferrule increased the longevity of the restored teeth. Failures of fiber posts were mainly due to post loss of retention, while metal post failures were mostly related to root fracture, post fracture and crown and/or post loss of retention. In conclusion, metal and fiber posts present similar clinical behavior at short to medium term follow-up. Remaining dental structure and ferrule increase the survival of restored pulpless teeth. Studies with longer follow-up are needed.

Silver nanoparticle incorporation effect on mechanical and thermal properties of denture base acrylic resins

ABSTRACT Objective The aim of the present study was to evaluate the mechanical and thermal characteristics of two denture base acrylic resins containing silver nanoparticles (AgNPs). Material and Methods Two different acrylic denture base resins (heat-polymerized and microwave polymerized) containing 0.3, 0.8 and 1.6 wt% AgNPs were evaluated for flexural strength, elastic modulus and impact strength. The glass transition temperature (Tg) and relative heat capacity (Cp) of the samples were determined from the Differential Scanning Calorimetry (DSC) results. For statistical analysis, two-way ANOVA and Tukey-HSD tests were performed. Results Addition of 0.8% and 1.6% AgNPs in microwave-polymerized resin significantly decreased the transverse strength and elastic modulus. In terms of impact strength, the addition of AgNPs has no effect on both resin groups. Glass transition temperature (Tg) was decreased with the addition of AgNPs for both denture base resins. Conclusions The incorporation of AgNPs, generally used for antimicrobial efficiency, affected the transverse strength of the denture base acrylic resins depending on the concentration of nanoparticles. Tg was decreased with the addition of AgNPs for both denture base resins.

Influência na resistência de união de pinos de fibra de vidro com e sem retenções mecânicas em função dos materiais utilizados para cimentação: teste de 'push-out' / Influence on the bond strength of glass fiber posts with and without mechanical retentions depending of materials used for cementing: push-out test

Este estudo teve como objetivo avaliar a influência na resistência de união de pinos de fibra de vidro (PFV) com retenções mecânicas (CRM) e sem retenções (SR), associados a três materiais: RelyX ARC cimento resinoso convencional dual com sistema adesivo Adper Single Bond (ASB), convencional de 2 passos; RelyX U200 cimento resinoso auto condicionante dual e resina flow SDR foto ativada, com sistema adesivo Prime & Bond 2.1 (PB), convencional de 2 passos; nos terços cervical (C), médio (M) e apical (A), por meio do teste de push-out. Sessenta incisivos bovinos foram selecionados, tiveram as coroas seccionadas para padronizar 17mm de raiz e foram submetidas ao tratamento endodôntico, para posterior cimentação do PFV. Foram divididas aleatoriamente em 2 grupos (N=30), quanto ao tipo de PFV: CRM - com retenções mecânicas (Glassix+plus no2) e SR - sem retenções (Exacto no2). Todos os PFV apresentavam formato cônico. Cada grupo foi subdividido em 3 (N=10), quanto ao tipo de material: cimento RelyX ARC+ASB; cimento RelyX U200 (auto condicionante) e resina SDR+PB. Todas as orientações dos fabricantes para tempo de manipulação e foto ativação do material foram rigorosamente respeitadas. As raízes foram mantidas em saliva artificial e decorridas 24h da cimentação dos PFV, foram seccionadas perpendicularmente ao longo eixo, obtendo 9 fatias de aproximadamente 1mm, cuja identificação foi feita de acordo com o terço correspondente. O teste de push-out foi realizado em máquina de ensaio universal com célula de carga de 50N; velocidade de 0,5mm/min, da direção apical para a cervical da fatia até que o pino fosse deslocado, respeitando o formato cônico do canal radicular. Todos os espécimes foram analisados em microscopia óptica, aumento de 200 vezes, quanto aos tipos de falha ocorrido. Os dados foram tabulados considerando as variáveis dos diferentes materiais utilizados para a cimentação, presença ou não de retenções mecânicas nos PFV e terços radiculares. Os valores de resistência de união (Ru) obtidos foram submetidos ao teste de normalidade Kolmogorov- Smirnov, à análise de variância a três critérios (ANOVA) e ao teste LSD de Fisher (p<0,05). Os resultados mostraram diferença estatisticamente significante nos terços C, M e A, respectivamente para os cimentos ARC com pino Glassix+plus, média e desvio padrão (MPa) a seguir, 8,50 (4,76); 6,99 (3,55); 4,71 (2,13) e U200 com pino Exacto: 9,40 (4,93); 8,02 (4,67); 4,67 (1,86); a resina SDR não interagiu significativamente com os PFV CRM 6,78 (2,72); 5,97 (2,45); 2,67 (1,55) e SR 7,24 (3,55); 6,86 (2,84); 4,10 (1,90). A análise microscópica mostrou predominância de falhas adesivas entre cimento e dentina e mista para todos os grupos. O cimento U200 com pino Exacto apresentou o melhor desempenho, seguido do ARC com pino Glassix+plus. A resina SDR teve desempenho semelhante para ambos os PFV. Todos os grupos apresentaram valores de Ru maiores no terço cervical, intermediários no terço médio e menores no terço apical.(AU)

This study aimed to evaluate the influence on the bond strength of glass fiber posts (GFP) with mechanical retention (WMR) and without retentions (NR), associated with three materials: RelyX ARC total-etching resin cement dual cure with Adper Single Bond (ASB) adhesive system, conventional 2 steps; RelyX U200 self-etching resin cement dual cure, and flowable resin SDR, activated by light, with Prime & Bond 2.1 adhesive system conventional 2 steps in the cervical (C), medium (M) and apical (A) thirds by the "push-out" test. Were selected sixty bovine incisors, had the crowns sectioned to root was standardized 17mm, were submitted to endodontic treatment, for cementing the GFP later. Were randomly divided into 2 groups (N=30), according to the GFP: WMR - with mechanical retentions (Glassix+plus ≠2) and NR - without retentions (Exacto ≠2). All GFP had conic shape. Each group was divided into 3 (N=10), according to material: RelyX ARC+ASB, RelyX U200 (self-etching) and flowable resin SDR+PB. All guidelines of manufacturers to handling time and cure time of the material were strictly adhered. The roots were kept in artificial saliva and 24 hours after GFP cementing it were sectioned perpendicular to the long axis, obtaining nine slices of approximately 1mm, which identification was done according to the corresponding third. The "push-out" test was performed with a universal test machine, 50N load cell; crosshead speed of 0.5 mm/min, the load was applied in an apical to cervical direction until the post dislodged from the specimen, respecting the conical shape of the root canal. Subsequently, all specimens were analyzed with optical microscopy 200 times increase to evaluate failure modes. Data were tabulated considering the materials used for cementing, presence or absence of mechanical retentions in GFP and root thirds. The bond strength values (BS) were submitted to Kolmogorov-Smirnov normality test, three-way ANOVA and Fisher's LSD test (p<0.05). The values showed statistically significant differences in thirds C, M and A, respectively for the ARC with Glassix+plus, average and standard deviation (MPa): 8.50 (4.76); 6.99 (3.55); 4.71 (2.13) and U200 with Exact post: 9.40 (4.93); 8.02 (4.67); 4.67 (1.86). SDR resin does not significantly interacted with GFP WMR 6.78 (2.72); 5.97 (2.45); 2.67 (1.55) and NR 7.24 (3.55); 6.86 (2.84); 4.10 (1.90). The microscopic analysis showed predominance of failure between cement and dentine and mixed for all groups. U200 cement with Exacto post had the best performance, followed by ARC with Glassix+plus post, SDR resin has similar performance for both GFP. All groups showed BS values higher in the cervical third, intermediate in the middle third and smaller in the apical third.(AU)

Efeito de inibidores da atividade proteolítica na resistência de união de pino de fibra de vidro à dentina radicular após 12 meses / Effect of proteolytic activity inhibitors on bond strength of glass-fiber post to radicular dentin up to 12 months

O estabelecimento de uma camada híbrida adequada no canal radicular representa um dos principais desafios clínicos devido à dificuldade de acesso. Dessa forma, o uso de inibidores proteolíticos poderia tornar-se um recurso favorável. O objetivo deste estudo foi avaliar o efeito de inibidores proteolíticos na união de pino de fibra de vidro fixado com cimento adesivo, considerando os terços radiculares e tempos distintos, por meio da resistência de união (RU). Cento e quarenta e quatro raízes bovinas foram selecionadas e divididas em 6 grupos de tratamento, e redivididas em 3 subgrupos de acordo com os tempos de avaliação de 24 horas, 6 e 12 meses (n=8). Após o tratamento endodôntico e desobturação padronizados, as raízes foram cimentadas com pinos de fibra de vidro cônicos (Exacto/Angelus). As raízes foram tratadas com sistema adesivo convencional de três passos, Adper Scotchbond Multipurpose/ 3M ESPE (SBMP) e cimento dual RelyX ARC/ 3M ESPE. Após prévia divisão, foram alocadas em grupos CN (Controle Negativo- sem pré tratamento associado), CP (Controle Positivo- com agentes ativador e catalisador), EDTA (ácido etilenodiamino tetra-acético a 17%), CHX (digluconato de clorexidina a 2%), E-5 (E- 64 a 5 µM) e E-10 (E-64 a 10 µM). Após 24 horas, as raízes foram seccionadas perpendicularmente ao longo eixo e identificadas quanto à região, obtendo-se fatias de 1 mm de espessura (cervical, médio e apical), que foram armazenadas em saliva artificial para serem testadas. Todas as fatias foram submetidas ao teste de extrusão (push-out) na máquina de teste universal (Instron) com célula de carga de 50 N a 0,5 mm/min. Os dados foram analisados pelo teste de ANOVA a três critérios e comparações múltiplas com Tukey, ambos com p<0,05. Após 24 horas, não se observou diferenças entre os tratamentos. Após 6 meses, a CHX demonstrou melhor desempenho, cujo efeito não se prorrogou até os 12 meses. O uso de inibidores proteolíticos não foram capazes de preservar a resistência de união dos pinos intrarradiculares até o tempo de 12 meses.(AU)

The adequate establishment of hybrid layer in the root canal on bonding process is still a clinical challenge due to its hard access. Thus, the use of proteolytic inhibitors could become a favorable tool. The aim of this study was to evaluate the effect of proteolytic inhibitors in the bonding of a glass- fiber post fixed with a luting cement, regarding the root thirds and different times through the bond strength. One hundred and forty four bovine roots were selected and divided into 6 treatment groups, and subdivided according to the time of evaluation of 24 hours, 6 and 12 months (n=8). After endodontic treatment and standardized removal procedure, the roots were cemented with tapered glass fiber posts (Exacto/ Angelus). The roots were treated with three-step etch-and-rinse adhesive system Adper Scotchbond Multipurpose/ 3M ESPE (SBMP) and dual cement RelyX ARC/ 3M ESPE. After previous division, CN (negative- control without pre associated treatment), CP (Control positive- with activator and catalyst agents) EDTA (17% ethylenediaminetetraacetic acid) CHX (2% chlorhexidine digluconate) E-5 (5µM E-64) and E-10 (10µM E-64). After 24h, the roots were sectioned perpendicular to the long axis and identified according to third in 1mm thick slices (cervical, middle and apical), which were stored in artificial saliva to be tested. All slices were subjected to extrusion tests (push-out) in the universal test machine (Instron) at 50 N load cell at 0.5 mm/min. Data were analyzed with three-way ANOVA and multiple comparisons with Tukey test, both with p <0.05. After 24 hours, no differences were observed between treatments. After 6 months, CHX showed better performance, which did not last up 12 months. The proteolytic inhibitors performed differently in the bonding process over time; only CHX promoted inhibition at 6 months. The use of proteolytic inhibitors were not able to maintain the bond strength of intraradicular posts up time of 12 months.(AU)

Relined fiberglass post: an ex vivo study of the resin cement thickness and dentin-resin interface

Abstract The aim of this study was to evaluate the thickness of resin cements in the root thirds when using conventional fiberglass posts (CP) and relined fiberglass posts (RP) in weakened roots and to evaluate the morphological characteristics of the dentin-resin interface. Forty human maxillary anterior teeth had the crown sectioned below the cemento-enamel junction. The canals were endodontically treated and weakened with diamond burs. Teeth were divided into four groups (n = 10): Group 1 - CP + RelyX ARC; Group 2 - CP + RelyX U200; Group 3 - RP + RelyX ARC; and Group 4 - RP + RelyX U200. Prior to luting, 0.1% Fluorescein and 0.1% Rhodamine B dyes were added to an adhesive and resin cement, respectively. Slices were obtained from the apical, middle, and cervical thirds of the root. Confocal laser scanning microscopy images were recorded in four areas (buccal, lingual, mesial, distal) of each third. In each area, four equidistant measures of the resin cement were made and the mean value was calculated. The interface morphology was observed. The data were submitted to three-way ANOVA and Tukey's test (α = 0.05). The interaction between fiberglass posts, resin cement, and root thirds was significant (p < 0.0001). The resin cement thicknesses were significantly lower for RP in comparison with CP, except in the apical third. There was no significant difference between the resin cements for RP. There was formation of resin cement tags and adhesive tags along the root for RP. RP favored the formation of thin and uniform resin cement films and resin tags in weakened roots.

Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS) and Block HC (BHC)] were pretreated as follows: (a) no treatment (None), (b) application of a ceramic primer (CP), (c) alumina-blasting at 0.2 MPa (AB), (d) AB followed by CP (AB+CP), and (e) glass-beads blasting at 0.4 MPa (GBB) followed by CP (GBB+CP). The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS) and ResiCem (RC)]. The bond strengths after 24 h (TC 0) and after thermal cycling (TC 10,000 at 4–60°C) were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05). Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p<0.05). AB showed significantly higher bond strength after TC 10,000 than the None group, while CP did not (p<0.05). GBB exhibited smaller surface defects than did AB; however, their surface roughnesses were not significantly different (p>0.05). The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05), but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05). Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP.