Biomechanical performance of three fiberglass post cementation techniques: Imaging, in vitro, and in silico analysis.

PURPOSE: The structural integrity of the resin cement layer, the bond strength, and the biomechanical behavior of different fiberglass post cementation techniques were evaluated. METHODS: Thirty-three bovine incisors were divided into three groups (n = 11): conventional fiberglass post (CFP), conventional fiberglass post in flared root canals (CFL), and relined fiberglass post (RFP). Six specimens from each group were submitted for high-resolution microcomputed tomography (µCT) to evaluate the integrity and presence/volume of voids at the resin cement layer. Finite element analysis (FEA) of two three-dimensional (3D) models of each group were conducted, one considered ideal (without interface defects) and another containing the conditions identified in the µCT analysis. Push-out bond strength tests were conducted for all specimens. RESULTS: The CFL group had the greatest mean values of void (Thirds cervical: 73.67; middle: 95.67; apical: 47.33) and gap concentration (Thirds cervical: 14.67; middle: 15.83; apical: 8.33) compared with CFP and RFP. A significant difference in bond strength was observed between the cervical (1.33 MPa) and middle thirds (1.85 MPa) compared with the apical third (4.85 MPa) of the CFL. A significant difference was observed in the bond strength in the CFL (1.33 MPa) and RFP (3.29 MPa) in the cervical third, which were statistically similar to the bond strength of the CFP. The tensile stress distributions were similar in most structures, localized in the cervical region on the lingual surface. CONCLUSIONS: Structural defects in the interface layer might influence the bond strength and biomechanical behavior under the different fiberglass post cementations.

Efficacy of two polishing systems in reestablishing the surface smoothness of posterior monolithic lithium disilicate restorations: One-year results of a split-mouth randomized controlled clinical trial.

STATEMENT OF PROBLEM: Selecting the optimal polishing procedure to reestablish surface smoothness after occlusal adjustment is essential for the long-term success of glass-ceramic restorations. While in vitro studies have shown different effective polishing protocols, clinical trials are lacking. PURPOSE: The purpose of this split-mouth controlled clinical trial was to evaluate the effectiveness of 2 polishing systems in reestablishing the surface smoothness of posterior monolithic lithium disilicate ceramic restorations. MATERIAL AND METHODS: Ninety-six restorations that required occlusal adjustment after bonding were randomized into 2 groups: Forty-eight restorations were polished by using the Exa Cerapol polishing kit, and the other 48 restorations were polished by using the Shofu polishing kit. The restorations were replicated with epoxy resin at 3 study times-after bonding (t1), after occlusal adjustment (t2), and after polishing (t3)-for quantitative roughness analysis (Ra). Representative specimens from each group were qualitatively analyzed by using a confocal laser microscope. Clinical analyses were performed after the polishing procedure and at 30, 180, and 365 days after the polishing procedure by following the United States Public Health Service (USPHS) criteria. ANOVA and the Tukey multiple comparisons parametric tests were computed (α=.05). The Kaplan-Meier test was used to analyze the survival rate of restorations. RESULTS: No statistically significant difference was found between the Exa Cerapol and Shofu groups (P=.086). A statistically significant difference was found between study times t1 and t2 and between t2 and t3 (both P<.001) in both experimental groups. No statistically significant difference was found between study times t1 and t3 (P=.181) in either experimental group. For the clinical criterion "integrity of restorations," all the elements analyzed indicated an alfa grade at all study times. The survival rate of the restorations was 100%. CONCLUSIONS: Both polishing kits were effective in reestablishing the surface smoothness of restorations after occlusal adjustment.

Oral health-related quality of life and satisfaction in edentulous patients rehabilitated with implant-supported full dentures all-on-four concept: a systematic review.

OBJECTIVE: Address oral health-related quality of life (OHRQoL) and patient satisfaction rehabilitated by the all-on-four concept as the primary outcome. MATERIAL AND METHODS: A search was performed in the PubMed/MEDLINE, Web of Science, and Cochrane databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis criteria (PRISMA). The PICO question was used to address the following specific question: "What is the level of oral health-related quality of life and satisfaction in edentulous patients and with atrophic jaws who received dental implants for full-arch implant-supported restorations following the all-on-four in the mandible or maxilla?" RESULTS: Eleven studies including 693 patients aged 55 to 71 years were selected. The shortest follow-up period was 3 months and the longest, 7 years. Regarding the OHRQoL assessment method and patient satisfaction, the oral health impact profile (OHIP) and the visual analog scale (VAS) were the most used. CONCLUSION: OHRQoL and satisfaction in patients whose rehabilitation was based on the all-on-four concept were high. However, the current evidence is still limited by the quality of the available studies, making long-term randomized studies necessary to establish the real effectiveness of this surgical-prosthetic approach. CLINICAL RELEVANCE: Carefully analyze the aspects related to satisfaction and oral health-related quality of life of rehabilitated patients with implant-supported total prostheses made according to the all-on-four concept, aiming to achieve success through procedures with greater predictability and less complexity, as these are directly associated with recovery oral health of edentulous individuals with less morbidity and minimized costs.

Role of adhesive systems on the luting interface's thickness of ceramic laminate veneers.

This in vitro study aimed to evaluate the effects of different luting protocols on the thickness of luting interface of ceramic laminate veneers. Thirty-six lithium disilicate blocks (7 × 8 × 0.6 mm) were cemented onto bovine enamel. They were divided into 6 groups based on the luting protocol (no previous photoactivation of the dental adhesive; previous activation of the dental adhesive only on enamel surface; and previous photoactivation of the dental adhesive on both the enamel surface and inner surface of ceramic laminate) and the luting materials used (Single Bond Universal/RelyX Veneer and Tetric N Bond/Variolink Veneer). The luting interface thickness of ceramic laminate veneers was evaluated using a laser scanning confocal microscope (n = 6). The luting interface measurements were analyzed using 2-way ANOVA and the Tukey least significant difference test (α = 0.05). Prior activation of the adhesive on the dental enamel and inside the ceramic laminate exhibited higher luting interface thickness than that with no prior photoactivation of both luting materials (p < 0.05). Specimens cemented with Tetric N Bond/Variolink Veneer, submitted for prior photoactivation of the adhesive on the dental enamel and on both dental enamel and inner surface of ceramic, exhibited lower luting interface thickness than those luted with Single Bond Universal/RelyX Veneer (p < 0.05). The prior photoactivation of dental adhesives influenced the thickness of luting interface in laminate restorations. Tetric N Bond/Variolink Veneer yielded more satisfactory results than Single Bond Universal/RelyX Veneer when the adhesive was light activated.

Materials Sealing Preventing Biofilm Formation in Implant/Abutment Joints: Which Is the Most Effective? A Systematic Review and Meta-Analysis.

The purpose of this systematic review was to evaluate the literature available for materials exhibiting the best efficacy in preventing biofilm formation in the interior of implants. We searched PubMed/MEDLINE, Scopus, and Cochrane databases. This review is registered with the PROSPERO database and followed the suitability of the PRISMA protocol. The initial search resulted in 326 articles from the databases. After they were read, 8 articles remained, and the inclusion and exclusion criteria were applied. Six of these 8 articles were classified as in vitro and 2 were classified as in situ. The regions of the implants evaluated ranged from the interface of the pieces to the occlusal upper access of the abutment. The implant connections evaluated the Morse taper, external connection, and internal connection. Meta-analysis of the quantitative data was performed at a significance level of .05. Cotton exhibited poor control of infiltration, even in combination with other materials. Isolated gutta-percha (GP) and polytetrafluoroethylene (PTFE) tape with composite resin (CR) or GP performed better as physical barriers. The best results for chemical barriers were observed by the application of 1% chlorhexidine gluconate (CG) gel, thymol varnish, and the deposition of Ag films onto the surface. The applied meta-analysis did not show a significant difference in comparison between the different types of implant connections (P > .05). The application of CG and thymol varnish antimicrobials was effective in preventing biofilm formation and easy clinical execution; these could be used in combination with CR, GP, and PTFE.

Influence of Light-Curing Intensity on Color Stability and Microhardness of Composite Resins.

The purpose of this study was to evaluate the intensity of light-curing units and its relationship with the color stability and microhardness of composite resins with different shades subjected to a thermocycling procedure. Eighty blocks (5.0 × 2.0 mm) of TPH Spectrum composite resin (Dentsply Sirona) were produced and distributed into four groups according to the light-curing units (EC 450, ECEL; Valo, Ultradent) and color of the resin material (A3; C3) (n = 20). Within each group, color stability was measured on half the sample (n = 10) using a UV-2450 visible UV spectrophotometer (Shimadzu), and Knoop hardness was measured on the other half (n = 10) using an HMV 2000 microhardness tester (Shimadzu) before and after thermocycling (12,000 cycles, 5°C and 55°C). Mann-Whitney test was performed on the color stability data; the microhardness data were analyzed using a three-way analysis of variance (ANOVA) and Tukey test (α = .05). The ANOVA results showed that thermocycling, distinct light intensity, and different colors of resin materials influenced the microhardness of the composite resins, which was evidenced by the A3 composite resin light-cured with a Valo polywave showing higher hardness values. There was no statistical difference in the color stability of the A3 composite resin; however, the C3 composite resin light-cured with an EC 450 singlewave light-curing unit showed higher color alteration values. In general, the Valo polywave light-curing unit imparted better mechanical property and color stability to both shades of the composite resins. The different shades of resin material influenced the hardness of the composite resins. Therefore, the light intensity of the light-curing units should be evaluated and monitored, as the amount of light intensity will interfere in the quality and longevity of resin restorations.

Role of adhesive systems on the luting interfaces thickness of ceramic laminate veneers

Abstract This in vitro study aimed to evaluate the effects of different luting protocols on the thickness of luting interface of ceramic laminate veneers. Thirty-six lithium disilicate blocks (7 × 8 × 0.6 mm) were cemented onto bovine enamel. They were divided into 6 groups based on the luting protocol (no previous photoactivation of the dental adhesive; previous activation of the dental adhesive only on enamel surface; and previous photoactivation of the dental adhesive on both the enamel surface and inner surface of ceramic laminate) and the luting materials used (Single Bond Universal/RelyX Veneer and Tetric N Bond/Variolink Veneer). The luting interface thickness of ceramic laminate veneers was evaluated using a laser scanning confocal microscope (n = 6). The luting interface measurements were analyzed using 2-way ANOVA and the Tukey least significant difference test (α = 0.05). Prior activation of the adhesive on the dental enamel and inside the ceramic laminate exhibited higher luting interface thickness than that with no prior photoactivation of both luting materials (p < 0.05). Specimens cemented with Tetric N Bond/Variolink Veneer, submitted for prior photoactivation of the adhesive on the dental enamel and on both dental enamel and inner surface of ceramic, exhibited lower luting interface thickness than those luted with Single Bond Universal/RelyX Veneer (p < 0.05). The prior photoactivation of dental adhesives influenced the thickness of luting interface in laminate restorations. Tetric N Bond/Variolink Veneer yielded more satisfactory results than Single Bond Universal/RelyX Veneer when the adhesive was light activated.

Emergence profile customization technique during implant transfer.

This case report aimed to describe the clinical considerations in oral rehabilitation with prostheses on implants in the anterior region, using emergence profile customization technique during implant transfer. A patient presented with a missing left upper central incisor and with not satisfactory esthetic in the other upper incisors. After diagnosis, a treatment plan was elaborated: implant placement in this region; ceramic laminates for teeth 11 and 22, and full crown for tooth 12. During the impression procedure, the implant transfer was customized by copying the gingival profile. The prostheses were made using IPS e.max ceramic system and luted with resin cement. The patient was submitted to annual follow-up examinations that did not show any irregularity or deficiency in the prostheses. The technique performed is a viable alternative that can be used in oral rehabilitation with implants involving anterior teeth because it allows a predictable level of adaptation.

Influence of resin cement thickness and temperature variation on mechanical behavior of dental ceramic fragment restoration.

To evaluate the stress behavior of ceramic fragment restoration, varying the thickness of the cement layer and intraoral temperature variation. A solid model of a upper lateral incisor was obtained and a defect at enamel distal/incisal edge was restored with a ceramic fragment. Based on this initial model, 4 different models (M) were built: M1 - absence of cement layer (CL) (0 µm of thickness); M2 - CL with an uniform thickness of 50 µm; M3 - CL with 50 µm at the margin of ceramics and 100 µm in the inner area far from margins; M4 - CL with 50 µm at the margin of ceramics and 200 µm in the inner area far from margins. The environment temperature changed from 5 °C to 50 °C in 4 increments. The finite element analysis was performed. Increase the cement layer thickness generated higher stress levels on ceramic surface in all temperatures, as well as on cement interface. In general hot temperature was the worst scenario for ceramic fragments integrity, since tensile and compressive stress were more intense. The maximum principal stress on ceramic fragment was found 90 MPa for M4 at 50 °C, followed for M3 (87 Mpa). For CL, the peak of stress was found for M3 at 5 °C (47 MPa). Is it possible to conclude that thick resin cement layer contribute to higher stress concentration on ceramic fragment, and extremely hot temperatures increase the risk of structural failure, since both ceramic and \cl are exposed to higher compressive and tensile stresses.

Restaurações cerâmicas delgadas sobre dentes sem preparo em diferentes regiões dos arcos dentais: relato de 2 casos clínicos / Thin ceramic restorations on unprepared teeth in different regions of the dental arches: report of 2 clinical cases / Restauraciones cerámicas finas en dientes no preparados en diferentes regiones de los arcos dentales: reporte de 2 casos clínicos

As reforçadas propriedades intrínsecas dos materiais cerâmicos, associados à adesão resinosa fundamentam a desenvoltura de técnicas restauradoras mais simplificadas, conservadoras e sem a necessidade de preparo dental prévio seja em dentição anterior ou posterior. Assim sendo, o trabalho tem como objetivo apresentar dois casos clínicos os quais abordaram a confecção de restaurações delgadas em dissilicato de lítio cimentadas sobre diferentes áreas dos arcos dentários, enfatizando o mesmo protocolo clínico, ou seja, ausência de preparos dentais e consequentemente a cimentação resinosa adesiva das restaurações. Caso Clínico 1: laminados cerâmicos nos elementos 13, 12, 11, 21, 22 e 23; Caso Clínico 2: facetas delgadas sobre os elementos 34, 35, 36 e 37. Ambos os casos clínicos com 1 ano de acompanhamento após a cimentação das restaurações. Conclui-se que houve a recuperação da estética e da função em ambos os casos apresentados e a confiabilidade e o sucesso em longo prazo do protocolo clínico descrito estão diretamente relacionados ao substrato dentário, aos fatores de adesividade dos materiais e as propriedades intrínsecas das cerâmicas(AU)

The reinforced intrinsic properties of the ceramic materials, associated with the resinous adhesion, support the development of restorative techniques that are simplified, conservative and without the need of previous dental preparation, either in anterior or posterior dentition. The objective of this study was to present two clinical cases which used thin restorations in lithium disilicate cemented in different areas of the dental arches, emphasizing the same clinical protocol, that is, the absence of dental preparations and, consequently, resinous cementation. Clinical Case 1: ceramic laminates veneers in elements 13, 12, 11, 21, 22 and 23; Clinical case 2: thin ceramic restorations on elements 34, 35, 36 and 37. At both cases with 1 year of follow-up after cementation of the restorations. It was concluded that there was recovery of aesthetics and function in both cases presented and the reliability and long-term success of the described clinical protocol are directly related to the dental substrate, the material adhesion factors and the intrinsic properties of the ceramics(AU)

Las propiedades intrínsecas reforzadas de los materiales cerámicos, asociadas con la adhesión resinosa, apoyan el desarrollo de técnicas restaurativas que son simplificadas, conservadoras y sin la necesidad de una preparación dental previa, ya sea en la dentición anterior o posterior. El objetivo de este estudio fue presentar dos casos clínicos que utilizaron restauraciones delgadas en disilicato de litio cementadas en diferentes áreas de los arcos dentales, enfatizando el mismo protocolo clínico, es decir, la ausencia de preparaciones dentales y, en consecuencia, la cementación resinosa. Caso Clínico 1: carillas cerámicas en los elementos 13, 12, 11, 21, 22 y 23; Caso clínico 2: restauraciones cerámicas delgadas en los elementos 34, 35, 36 y 37. Ambos casos con 1 año de seguimiento después de la cementación de las restauraciones. Se concluyó que hubo recuperación de la estética y la función en ambos casos presentados y la fiabilidad y el éxito a largo plazo del protocolo clínico descrito están directamente relacionados con el sustrato dental, los factores de adhesión del material y las propiedades intrínsecas de la cerámica(AU)

Restabelecimento estético e funcional de paciente com amelogênese imperfeita utilizando restaurações cerâmicas metal-free / Aesthetic and functional re-establishment of patient with imperfect amelogenesis using metal-free ceramic restorations / Restablecimiento estético y funcional del paciente con amelogénesis imperfecta con restauraciones de cerámica sin metal

A amelogênese imperfeita compreende um grupo de condições com alterações do desenvolvimento na estrutura do esmalte dentário que afetam a dentição decídua e permanente e as principais implicações clínicas são: estética prejudicada, hipersensibilidade dentinária, dificuldade na higiene bucal, cáries recorrentes, inflamação gengival e perda da dimensão vertical. O tratamento varia de acordo com o tipo e a gravidade do caso, a fase do desenvolvimento dentário, o nível socioeconômico e as expectativas e anseios do paciente, podendo ser levados anos até o estabelecimento do tratamento definitivo. O presente trabalho tem como objetivo relatar e descrever as etapas clínicas de um caso de amelogênese imperfeita com restabelecimento da estética e função através de laminados cerâmicos ultrafinos, confeccionados em IPS e.max (IvoclarVivadent), com acompanhamento de um ano após a cimentação das restaurações. Conclui-se que os laminados cerâmicos podem ser uma alternativa interessante para o tratamento definitivo de casos mais brandos de amelogênese imperfeita, com otimização dos resultados estéticos e recuperação da autoestima do paciente(AU)

The imperfect amelogenesis comprises a group of conditions with developmental changes in dental enamel structure that affect the deciduous and permanent dentition and the main clinical implications are: impaired esthetics, dentine hypersensitivity, difficulty in oral hygiene, recurrent caries, gingival inflammation and loss of vertical dimension. Treatment varies according to the type and severity of the case, the dental development phase, the socioeconomic level, and the expectations and wishes of the patient, and it may take years to establish definitive treatment. The objective of the present study is to report and describe the clinical stages of a case of imperfect amelogenesis with re-establishment of aesthetics and function through ultrafine ceramic laminates, made of IPS e.max (IvoclarVivadent), followed one year after the cementation of restorations. It is concluded that ceramic laminates can be an interesting alternative for the definitive treatment of milder cases of imperfect amelogenesis, with optimization of aesthetic results and recovery of the patient's self-esteem(AU)

La amelogénesis imperfecta comprende un grupo de condiciones con alteraciones del desarrollo en la estructura del esmalte dental que afectan la dentición decidua y permanente y las principales implicaciones clínicas son: estética prejudicada, hipersensibilidad dentinaria, dificultad en la higiene bucal, caries recurrentes, inflamación gingival y pérdida de la enfermedad dimensión vertical. El tratamiento varía de acuerdo con el tipo y la gravedad del caso, la fase del desarrollo dental, el nivel socioeconómico y las expectativas y anhelos del paciente, pudiendo ser llevados años hasta el establecimiento del tratamiento definitivo. El presente trabajo tiene como objetivo relatar y describir las etapas clínicas de un caso de amelogénesis imperfecta con restablecimiento de la estética y función con carillas de cerâmica realizadas con IPS e.max (IvoclarVivadent), con acompañamiento de un año después de la cementación de las restauraciones . Se concluye que las carrillas cerámicas pueden ser una alternativa interesante para el tratamiento definitivo de casos más blandos de amelogénesis imperfecta, con optimización de los resultados estéticos y recuperación de la autoestima del paciente(AU)

Sealing the Screw Access Channel with Polytetrafluoroethylene Tape: Advantages of the Technique.

The aim of this article is to describe the procedure for sealing the screw access channel using plastic tape, polytetrafluoroethylene, in screw- or cement-retained implant-supported prostheses. This technique is viable and easily performed, and the functional and esthetic results are satisfactory.

Epidemiological Data and Survival Rate of Removable Partial Dentures.

INTRODUCTION: The use of removable partial denture (RPD) is considered as low-cost and common treatment option to rehabilitate edentulous areas. AIM: This study aimed to investigate the epidemiological data of patients rehabilitated with removable partial denture (RPD) in order to assess treatment survival rate and failures. MATERIALS AND METHODS: Epidemiological data and medical records of patients treated with RPD between 2007 and 2012 at the RPD discipline of a Brazilian University (Aracatuba Dental School- UNESP) were evaluated as well as dental records of patients who underwent RPD treatments (fabrication or repairs) between 2000 and 2010. Factors such as gender, age, presence of systemic disease, main complaint, edentulous arch, period and cause of denture replacement and the prosthesis characteristics were recorded. The chi-square test was used to assess the differences between the variables and the Kaplan Meyer to assess the survival of the RPDs evaluated. RESULTS: A total of 324 maxillary RPD and 432 mandibular RPD were fabricated. Most of the patients were women aging 41 to 60-year-old. The number of mandibular RPD Kennedy class I (26%) was statistically higher for the maxillary arch (p<.05). There was no association between main complaint to gender or the presence of systemic disease. The lingual plate was the most common major connector used in the mandible (32%). The main reason for altering the design of replaced RPDs were changes during treatment plan. CONCLUSION: The number of patients who require RPD is large; most of RPDs are Kennedy Class I. A good treatment plan is very important for achieving a positive treatment outcome, and it is strictly related to the survival rate.

Assessment of Satisfaction Level of Edentulous Patients Rehabilitated with Implant-Supported Prostheses.

PURPOSE: Edentulism usually leads to esthetic, functional, and emotional discomfort resulting in a loss of self-esteem and a decrease of the patient's quality of life. Dental implants provide new possibilities to ensure the comfort and efficacy of prosthetic rehabilitation. The aim of this study was to evaluate the satisfaction level of patients rehabilitated using the Brånemark protocol or overdenture implant-supported prostheses. MATERIALS AND METHODS: Fifty-two patients were rehabilitated using the Brånemark protocol and 23 using overdenture prostheses. Then, an adapted oral health-related quality of life questionnaire was administered in addition to a clinical exam to determine the condition of the dental implants and prostheses. The results for treatment expectation, understanding of the type of treatment, phonetic function, chewing comfort, pain, and self-esteem improvement were analyzed with Fisher exact test (P ≤ .05). RESULTS: Both treatments presented satisfaction of above 87%, with no statistical difference between them. Eighty-two percent of patients treated with overdenture prostheses and 80.8% of those treated with the Brånemark protocol had no complaint of pain (P = .087). CONCLUSION: The treatments analyzed in this study were highly satisfactory with regard to functional and esthetic factors, resulting in an increase in self-esteem and quality of life. The psychological factor is a complex variable in patient satisfaction that directly influences quality of life. Considering the desires of patients in choosing the type of prosthesis is critical to treatment success.

Stress distribution in delayed replanted teeth splinted with different orthodontic wires: a three-dimensional finite element analysis.

AIM: The aim was to evaluate the biomechanical behavior of the supporting bony structures of replanted teeth and the periodontal ligament (PDL) of adjacent teeth when orthodontic wires with different mechanical properties are applied, with three-dimensional finite element analysis. MATERIALS AND METHODS: Based on tomographic and microtomographic data, a three-dimensional model of the anterior maxilla with the corresponding teeth (tooth 13-tooth 23) was generated to simulate avulsion and replantation of the tooth 21. The teeth were splinted with orthodontic wire (Ø 0.8 mm) and composite resin. The elastic modulus of the three orthodontic wires used, that is, steel wire (FA), titanium-molybdenum wire (FTM), and nitinol wire (FN) were 200 GPa, 84 GPa, and 52 GPa, respectively. An oblique load (100 N) was applied at an angle of 45° on the incisal edge of the replanted tooth and was analyzed using Ansys Workbench software. The maximum (σmax) and minimum (σmin) principal stresses generated in the PDL, cortical and alveolar bones, and the modified von Mises (σvM) values for the orthodontic wires were obtained. RESULTS: With regard to the cortical bone and PDL, the highest σmin and σmax values for FTM, FN, and FA were checked. With regard to the alveolar bone, σmax and σmin values were highest for FA, followed by FTM and FN. The σvM values of the orthodontic wires followed the order of rigidity of the alloys, that is, FA > FTM > FN. CONCLUSION: The biomechanical behavior of the analyzed structures with regard to all the three patterns of flexibility was similar.

Zirconia-based dental crown to support a removable partial denture: a three-dimensional finite element analysis using contact elements and micro-CT data.

Veneer fracture is the most common complication in zirconia-based restorations. The aim of this study was to evaluate the mechanical behavior of a zirconia-based crown in a lower canine tooth supporting removable partial denture (RPD) prosthesis, varying the bond quality of the veneer/coping interface. Microtomography (µCT) data of an extracted left lower canine were used to build the finite element model (M) varying the core material (gold core - MAu; zirconia core - MZi) and the quality of the veneer/core interface (complete bonded - MZi; incomplete bonded - MZi-NL). The incomplete bonding condition was only applied for zirconia coping by using contact elements (Target/Contact) with 0.3 frictional coefficients. Stress fields were obtained using Ansys Workbench 10.0. The loading condition (L = 1 N) was vertically applied at the base of the RPD prosthesis metallic support towards the dental apex. Maximum principal (σmax) and von Mises equivalent (σvM) stresses were obtained. The σmax (MPa) for the bonded condition was similar between gold and zirconia cores (MAu, 0.42; MZi, 0.40). The incomplete bonded condition (MZi-NL) raised σmax in the veneer up to 800% (3.23 MPa) in contrast to the bonded condition. The peak of σvM increased up to 270% in the MZi-NL. The incomplete bond condition increasing the stress in the veneer/zirconia interface.

Effect of long-term storage on nanomechanical and morphological properties of dentin-adhesive interfaces.

INTRODUCTION: To evaluate the influence of storage time on the elastic modulus, micromorphology, nanoleakage, and micromechanical behavior of the dentin-adhesive interfaces of five adhesive systems (Scotchbond Multi-Purpose, Clearfil SE Bond, One Up Bond F, Adper Easy One, and Filtek LS Adhesive) after 24h (T0) and 12 months (T1). METHODS: Fifty teeth were restored and distributed according to each adhesive system (n=10). At least four specimens were obtained from each tooth. One specimen was evaluated under SEM to obtain the micromorphology of dentin-adhesive interface (DAI). Two specimens were used to assess nanoleakage, one tested in T0 and the other in T1. The last specimen was used for nanoindentation, in T0 and T1, to obtain the initial and final mechanical properties of DAI structures. Two non-restored teeth were evaluated under SEM to obtain the dentin morphology. Laboratorial data were used to build 15 finite element models to assess the maximum principal stress in each time of analysis. RESULTS: Storage resulted in hydrolysis of the dentin-adhesive interfaces for all groups. Silver impregnation increased for all groups after 1 year storage (p<.05), except for Clearfil SE Bond. In general, a decrease in elastic modulus values was observed for all groups from T0 to T1 (p<.05), mainly at the hybrid layer. The FEAs showed higher stress levels at T1 than T0 simulations for all adhesives. CONCLUSION: At T1, degradation occurred at the dentin-adhesive interface formed by all adhesives, and the intensity of degradation differed depending on the type of adhesive system used. The interface formed by the self-etching primer containing the 10-MDP functional monomer showed the highest stability among the adhesive systems after 12 months of storage.

Surgical techniques for maxillary bone grafting - literature review.

For oral rehabilitation with implant-supported prostheses, there are required procedures to create the bone volume needed for installation of the implants. Thus, bone grafts from intraoral or extraoral donor sites represent a very favorable opportunity. This study aimed to review the literature on the subject, seeking to discuss parameters for the indications, advantages and complications of techniques for autogenous bone grafts.

Influence of the veneer-framework interface on the mechanical behavior of ceramic veneers: a nonlinear finite element analysis.

STATEMENT OF PROBLEM: The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures. PURPOSE: The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions. MATERIAL AND METHODS: The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework. RESULTS: Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used. CONCLUSION: Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support.

Surgical techniques for maxillary bone grafting - literature review / Técnicas cirúrgicas para a enxertia óssea dos maxilares - revisão da literatura

For oral rehabilitation with implant-supported prostheses, there are required procedures to create the bone volume needed for installation of the implants. Thus, bone grafts from intraoral or extraoral donor sites represent a very favorable opportunity. This study aimed to review the literature on the subject, seeking to discuss parameters for the indications, advantages and complications of techniques for autogenous bone grafts.

Para a reabilitação bucal com as próteses implantossuportadas é necessário a realização de procedimentos para criar o volume ósseo necessário para a instalação dos implantes. Com isso, os enxertos ósseos provenientes de áreas doadoras intrabucais ou extrabucais, representam uma possibilidade bastante favorável. O presente trabalho objetivou realizar uma revisão da literatura em que procurou discutir parâmetros para as indicações, as vantagens e complicações para as técnicas dos enxertos ósseos autógenos.