Bond strength of prefabricated and CAD-CAM milled glass fiber post-and-cores luted with conventional, universal, and self-adhesive composite resin cement.

STATEMENT OF PROBLEM: Little is known about the effect of different composite resin cements on the bond strength of prefabricated and milled glass fiber post-and-cores. PURPOSE: The purpose of this in vitro study was to compare the push-out bond strengths of root dentin and standard, relined, or computer-aided design and computer-aided manufacturing (CAD-CAM) glass fiber post-and-cores luted with conventional, universal, or self-adhesive composite resin cement. MATERIAL AND METHODS: Post spaces were prepared in 90 premolars. Standard and relined prefabricated and CAD-CAM-milled glass fiber post-and-cores were luted with conventional (RelyX ARC; 3M ESPE), universal (RelyX Ultimate; 3M ESPE), and self-adhesive (RelyX U200; 3M ESPE) composite resin cement (n=10). All specimens were thermally aged (5000 cycles at 5°C and 55°C with a 20-second dwell time) and mechanical fatigue (1 000 000 cycles at 2 Hz, 50-N load). The specimens were sectioned perpendicularly to the root long axis into 1-mm-thick sections (apical, middle, and cervical root thirds), the push-out bond strength was determined, and the mode of failure recorded. Data were submitted to the Kruskal-Wallis test followed by the Bonferroni-Dunn multiple comparison test (α=.05). RESULTS: Push-out bond strength values did not differ (P>.05) among posts at the same root thirds. Standard posts showed higher bond strength than CAD-CAM at the apical third for data grouped by composite resin cements (P<.001). The cervical root thirds had higher bond strength than the apical thirds (P<.05). The cervical, middle, and apical root thirds showed decreasing bond strength values for each type of post for data grouped by composite resin cement (P<.001). Adhesive failures at the dentin-cement interface were predominant. CONCLUSIONS: The type of posts and cements did not affect the bond strength of glass fiber posts. The cervical root thirds had better bonding performance than the apical thirds.

Digital smile design and mock-up technique for esthetic treatment planning with porcelain laminate veneers.

The use of digital tools offers a new perspective to daily clinical activities. The digital information serves as a starting point for a wax-up and intraoral mock-up, which is widely reported in literature as an objective and efficient communication tool among dentist, patient, and technician. This case report of a maxillary anterior rehabilitation demonstrates esthetic planning with the digital smile design (DSD) system and a direct mock-up technique. After preoperative photographs were obtained, digital planning was created using DSD. However, due to differences in virtual simulation, a direct mock-up with composite resin was performed. Porcelain laminate veneers using feldspathic ceramics were used to restore the anterior teeth. Many times, the DSD simulation is not enough for the patient to understand and observe the changes that will be performed on the anterior teeth. This combination of techniques can offer predictability to results as well increasing the patient expectation satisfaction.

Effect of surface treatments on the bond strength of CAD/CAM fiberglass posts.

BACKGROUND: There is no ideal protocol for the surface treatment of fiber posts, especially when using a computer-aided design/computer-aided manufacturing (CAD/CAM) experimental fiberglass block. The purpose of this study was to evaluate the bond strength of a CAD/CAM customized glass fiber post and core after applying different surface treatment techniques. MATERIAL AND METHODS: Forty premolars were prepared to receive a customized CAD/CAM glass-fiber post and core obtained from an experimental block of glass fiber and epoxy resin. The specimens were randomly distributed in 4 groups (n=10) according to the post and core surface treatment: ETH - 70% ethanol; HP - 24% hydrogen peroxide for 1 minute; ETH/S - 70% ethanol + silane; HP/S - 24% hydrogen peroxide + silane. The universal adhesive containing silane was applied on the posts and prepared post spaces in all groups. The posts were cemented using dual cure resin cement. The specimens were stored in distilled water at 37°C for 24 h, cut (two slices of 1 mm for each root third - coronal, middle, and apical) and subjected to push-out test (0.5 mm/min). Data was subjected to two-way ANOVA (surface treatment and root third) and Tukey's test (α=0,05). RESULTS: There was no significant difference of bond strength values among groups, regardless the surface treatment (p >0.05). There was significant difference on bond strength values for the different root thirds (p<0.05) (coronal>middle=apical). CONCLUSIONS: The different surface treatment and application of additional silane in the CAD/CAM customized glass-fiber post and core does not interfere on bond strength values. The root dentin third interfered on the bond strength, with higher values for the coronal third. Key words:Post and core technique, cad/cam, shear strength, hydrogen peroxide.

Scanning of root canal impression for the fabrication of a resin CAD-CAM-customized post-and-core.

Customization of post-and-cores using computer-aided design and computer-aided manufacturing (CAD-CAM) requires the scanning of a pattern and the subsequent digital design. This technique describes a method of fabricating a CAD-CAM-customized post-and-core designed from a scanned polyvinyl siloxane impression and milled from a nanoparticle/nanocluster-filled resin block. The polyvinyl siloxane impression allowed a faster and more efficient customization of the CAD-CAM post-and-core than a conventional acrylic resin pattern. The properties of the nanoparticle/nanocluster filled resin block make the material suitable for chairside CAD-CAM post-and-core fabrication.

Effect of CAD/CAM glass fiber post-core on cement micromorphology and fracture resistance of endodontically treated roots.

PURPOSE: To investigate the fracture resistance of weakened roots restored with prefabricated or CAD/CAM-customized posts and cores as well as the thickness of the cement film and the presence of voids in the cement. METHODS: The roots of 40 human premolars were weakened by removing internal dentin with a diamond bur (2.5 mm in the coronal third and 1.5 mm in the apical third) and restored with prefabricated posts (PPs) or customized posts (CPs) with or without a zirconia crown (n= 10). Posts and crowns were cemented with resin cement. Microtomography was used to determine the thickness of the cement film and whether voids were present. After fatigue testing (1 million cycles, 50 N, 5 Hz, 36.5°C), the specimens underwent compression testing with an oblique load (30°, 1 mm/minute) and fracture strengths were recorded (N). Fracture strength and film thickness were analyzed with ANOVA and the Games-Howell test; the variable presence of voids was analyzed with the Mann-Whitney test (α= 5%). RESULTS: Mean fracture strengths varied between 640.4 and 792.9 N and did not differ significantly between groups. The CP group had a thinner cement film and fewer voids than the PP group. There was a positive, statistically significant correlation (Spearman, R=0.488, P= 0.029) between these variables. CLINICAL SIGNIFICANCE: CAD/CAM-manufactured glass-fiber posts and cores do not affect the fracture strength of flared root canals or cause catastrophic failure of the root when used with zirconia crowns.

Estudo da resistência coesiva de cimentos resinosos convencionais e autoadesivos / Study of the cohesive strength of conventional and selfadhesive resin cements

O presente estudo teve como objetivo avaliar a resistência coesiva e o módulo de elasticidade de cimentos resinosos à tração e compressão. Os 15 espécimes foram divididos em 3 grupos: G1: AllCem, G2: Rely X U100, G3: Rely X ARC e submetidos a dois testes mecânicos: tração e compressão. Foram obtidos os resultados de resistência e módulo de elasticidade à tração e compressão dos cimentos resinosos. Os resultados foram avaliados estatisticamente por meio da ANOVA e múltiplas comparações de Games-Howell. Para a tração, a ANOVA revelou diferenças significativas entre os valores médios segundo o cimento (p<0.05). O teste de múltiplas comparações de Games-Howell para a tensão de ruptura mostrou que o cimento resinoso Rely X U100 apresentou os menores valores (21.91 ± 4.97 MPa), seguido pelo AllCem (23.13 ± 5.51 MPa) e pelo Rely X ARC (36.10 ± 8.27 MPa), onde o Rely X ARC diferiu estatisticamente doRely X U100 e doAllCem. ORely X U100 e AllCemnão revelaram diferenças entre si (p<0.05). No teste de compressão, o cimento Rely X U100 também apresentou os menores valores (134.57 ± 48.93 MPa), seguido do Rely X ARC (145.64 ± 32.76 MPa) e AllCem (243.71 ± 29.75 MPa), onde os cimentos Rely X U100 e Rely X ARC diferiram estatisticamente do AllCem e não revelaram diferenças entre si (p<0.05). Concluiu-se que os cimentos resinosos duais convencionais estudados apresentaram maiores valores de resistência à tração quando comparados ao cimento resinoso dual autoadesivo. A resistência coesiva à compressão foi maior que à tração para todos os cimentos resinosos estudados (AU).

The aim of the present study was to evaluate the cohesive strength and elastic modulus of resin cements subjected to the tensile and compression strength. Fifteen specimens were divided into 3 groups: G1: Allcem, G2: Rely X U100, G3: Rely X ARC, and subjected to two mechanical testing: tensile and compression. Strength and elastic modulus results of tension and compression tests of resin cements were obtained. The results were statistically analyzed by ANOVA and multiple comparisons of Games-Howell. For tensile test, the ANOVA revealed significant differences between the mean values according to the cement (p <0.05). The test multiple Games-Howell comparisons for the break to tensile showed that the resin cement Rely X U100 showed the lowest values (21.91 ± 4.97 MPa), followed by Allcem (23:13 ± 5:51 MPa) and the Rely X ARC (36.10 ± 8.27 MPa ), where the Rely X ARC differed from Rely X U100 and Allcem. The Rely X U100 and Allcem revealed no differences (p<0.05). In the compression test, Rely X U100 cement also had the lowest values (134.57 ± 48.93 MPa), followed by Rely X ARC (145.64 ± 32.76 MPa) and Allcem (243.71 ± 29.75 MPa), where cement Rely X U100 and Rely X ARC differed from the Allcem and revealed no differences (p <0.05). It was concluded that conventional dual resin cements studied showed higher tensile strength when compared to the dual-cured self-adhesive cement. The cohesive compressive strength was greater than to tensile for all resin cements studied (AU).

Determination of final occlusal vertical dimension by cephalometric analysis

Introduction: Most of techniques for determining the occlusal vertical dimension (OVD) of edentulous patients are based on soft tissues references, which lead to measurement discrepancies. Objective: To propose a method to obtain the OVD of edentulous patients during the confection of complete dentures considering the lower facial height established by Ricketts (LFHr) or the lower facial height obtained from cephalometric analysis of dentulous patients (LFHd). Material and methods: The OVD of 11 edentulous patients was determined by the association of 3 clinical methods. On each patient's bite plates a metallic ball was fixed and the patient was submitted to lateral radiographic to obtain the lower facial height (LFHe) from cephalometric analysis. Additionally, from 40 lateral cephalograms of dentulous patients the LFHd was obtained. After that, the distance between metallic balls (DMB, in mm) was calculated to verify the linear difference when LFHe was changed to LFHd or LFHr, which provided the amount of wax to be added or removed from the bite plates, establishing a new method of OVD determination. LFHe, LFHd and LFHr values were submitted to t e z statistical tests and DMB differences were analyzed by Student's t-test (α=0.05). Results: LFHr (47.0±4.0o a) was statistically higher than LFHd (44.9±5.6o b) and LFHe (43.5±3.5o b). There was statistical difference on linear discrepancies calculated between the LFHe and LFHd (1.7±4.1mm a) or LFHr (4.2±4.1mm b). Conclusion: The use of the cephalometric analysis showed to be a useful auxiliary tool in determining the intermaxillary relationship. However, this method must be associated with different clinical methods of OVD determination and it is recommended that regional references are used to calculate the linear discrepancies.

Customized fiber glass posts. Fatigue and fracture resistance.

PURPOSE: To evaluate the root fracture strength of human single-rooted premolars restored with customized fiberglass post-core systems after fatigue simulation. METHODS: 40 human premolars had their crowns cut and the root length was standardized to 13 mm. The teeth were endodontically treated and embedded in acrylic resin. The specimens were distributed into four groups (n=10) according to the restorative material used: prefabricated fiber post (PFP), PFP+accessory fiber posts (PFPa), PFP+unidirectional fiberglass (PFPf), and unidirectional fiberglass customized post (CP). All posts were luted using resin cement and the cores were built up with a resin composite. The samples were stored for 24 hours at 37 degrees C and 100% relative humidity and then submitted to mechanical cycling. The specimens were then compressive-loaded in a universal testing machine at a crosshead speed of 0.5 mm/minute until fracture. The failure patterns were analyzed and classified. Data was submitted to one-way ANOVA and Tukey's test (alpha = 0.05). RESULTS: The mean values of maximum load (N) were: PFP - 811.4 +/- 124.3; PFPa - 729.2 +/- 157.2; PFPf- 747.5 +/- 204.7; CP - 762.4 +/- 110. Statistical differences were not observed among the groups. All groups showed favorable restorable failures. Fiberglass customized post did not show improved fracture resistance or differences in failure patterns when compared to prefabricated glass fiber posts.

Three-year follow up of customized glass fiber esthetic posts.

Customized glass fiber posts that is well adjusted into the root canal and have mechanical properties similar to those of dentin may be a suitable treatment for severely compromised endodontically treated teeth. This article reports a 3-year follow up of severely damaged endodontically treated teeth restored with unidirectional fiber glass customized post and core system instead of a conventional fiber post. The fabrication of this glass fiber customized post is a simple technique, providing an increased volume of fibers into the root canal, and an adequate polymerization of the post-core system. Over a three-year period, the treatments demonstrated good clinical and radiographic characteristics, with no fracture or loss of the post and/or crown. This technique can be considered effective, less invasive, and suitable for restore endodontically treated teeth.

Adaptação marginal em prótese livre de metal, observada por meio de microscopia eletrônica de varredura, após três anos em função / Marginal fit of metal-free crown, observed in scanning electron microscope after three years in function

Introdução: As cerâmicas são consideradas uma excelente alternativa como material estético restaurador, entretanto questões relevantes, como adaptação marginal, exigem um maior critério na confecção quando comparadas aos sistemas convencionais. Objetivo: Este trabalho avaliou a adaptação marginal de uma coroa In-Ceram confeccionada sobre um dente que, após 3 anos, teve sua extração indicada pela ortodontia. Material e métodos: A avaliação deu-se por meio de microscópio eletrônico de varredura. Resultados e conclusão: Foram encontrados valores de falta de adaptação entre 157 e 390 um, obtendo uma média estatística acima do considerado aceitável clinicamente pela literatura.

Introduction: Ceramics are considered an excellent choice as esthetic restorative material, but relevant questions like marginal fit require more attention in manufacturing than conventional systems. Objective: This work evaluated the marginal adaptation of an In-Ceram crown over a tooth that, after three years, had been indicated to extraction by orthodontics. Material and methods: The evaluation was by mean scanning electron microscope. Results and conclusion: It was found values of gaps between 157 and 390 um, getting a statistic average considered greater than the accepted by literature.

Evaluation of the marginal adaptation of a fibre glass reinforced resin crown using a scanning electronic microscope / Avaliação da adaptação marginal de coroa deresina reforçada com fibra de vidro emmicroscópio eletrônico de varredura

Introduction and objective: Dental prostheses manufactured using reinforced resins are an alternative to the rehabilitative treatment of one or more dental elements. With the aim of forecasting the longevity of these prosthetic pieces, this study evaluated the marginal adaptation of a complete crown made from fibreglass reinforced resin. Material and methods: A tooth having orthodontic indication for extraction was prepared and a prosthetic piece was cemented over it so that, 48 hours later, the extraction could take place. The ensemble was taken in a laboratory and was examined using a scanning electron microscope (SEM). There were made 30 readings in a 8mm toothcement-restoration interface and revealed various gaps throughout the sample. Results: The lowest value found was 15,82 µm and the highest was 72,81 µm showing an average value of 40,82 µm. Conclusion: The gaps were within the limits of clinical tolerance and considering the clinical difficulty in making the prosthetic piece, the treatment was shown to be satisfactory with regard to marginal adaptation.

Introdução e objetivo: As próteses fabricadas com resinas reforçadas são alternativas para o tratamento reabilitador de um ou mais elementos dentários. Objetivando prever a longevidade dessas peças, este trabalho avaliou a adaptação marginal de uma coroa total confeccionada com resina reforçada com fibra de vidro. Material e métodos: Um dente com indicação ortodôntica de exodontia foi preparado e sobre ele uma peça protética foi cimentada para que, 48 horas depois, a extração fosse executada. O conjunto foi levado ao laboratório para leitura em microscópio eletrônico de varredura (MEV). Foram feitas 30 leituras em uma interface de dente-cimento-restauração de 8 mm e reveladas diferentes gaps em toda a amostra. Resultados: O menor valor achado foi de 15,82 µm, e o maior de 72,81 µm, resultando em uma média de 40,82 µm. Conclusão: As gaps estavam dentro dos limites de tolerância clínica e, considerando a dificuldade clínica de produção da peça protética, o tratamento mostrou-se satisfatório no que concerne à adaptação marginal.