RESUMO
OBJECTIVE: To evaluate the microstructure and the influence of applying universal adhesive only versus universal adhesive with additional silane application on shear bond strength (SBS) to four different lithium disilicate ceramic (LDC) materials. MATERIAL AND METHODS: Specimens (n = 240, 1.5 mm thick) cut from four different CAD/CAM materials were polished and etched with 4.5% hydrofluoric (HF) acid according to manufacturers' instructions (20 s: IPS e.max CAD, n!ce; 30 s: Amber Mill, CEREC Tessera). For cementation, either universal adhesive only or silane + universal adhesive were applied before prefabricated composite cylinders were cemented using a dual-cure resin cement. SBS testing was performed either after 24 h or after 20,000 cycles thermocycling +2 months water storage. Surfaces were analyzed with stereomicroscope for failure mode and with scanning-electron microscopy for microstructure of the LDC. Statistical analysis of the data was performed with non-parametric tests at α = 0.001. RESULT: SBS values for non-aged specimens ranged from 29.08 to 17.87 MPa and for aged specimens from 22.24 to 3.01 MPa. SBS was significantly reduced when silane was omitted after aging, (p < 0.001). Failure mode was mostly mixed with some cohesive failures in the LDC. CONCLUSION: Bond strengths are highly affected by the CAD/CAM LDC and their microstructures. The application of silane after hydrofluoric etching is still essential to obtain long-term bonding, irrespective of the presence of silane in the universal adhesive. Water degradation can significantly affect long-term bonding to novel LDC. CLINICAL SIGNIFICANCE: When using a universal adhesive for bonding to LDC restorations, the best long-term bond is achieved if an additional application of silane precedes the universal adhesive.
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Colagem Dentária , Silanos , Silanos/química , Propriedades de Superfície , Porcelana Dentária/química , Cerâmica/química , Cimentos de Resina/química , Água , Teste de MateriaisRESUMO
OBJECTIVE: To review the ultrastructural characteristics of novel lithium disilicate based glass ceramics (LDC), how their manufacturing process influences their structure and their clinical use. OVERVIEW: Lithium disilicate based glass ceramic has been successfully used for indirect restorations ranging from partial tooth coverage up to tooth replacement for over 20 years. It combines esthetic and mechanical properties, unlike any other indirect material which makes it an indispensable part of esthetic and restorative dentistry. Recently, novel LDCs have been introduced to the market. Parameters for their use and their microstructure are still not been widely known. This article will review these materials and highlight with high-resolution scanning electron microscopic images their structural aspects and their resulting clinical relevance. CONCLUSION: Restorations made from LDCs are reliable and can be predictably used only when proper guidelines and protocols during manufacturing and clinical use are followed. For novel LDCs manufacturing and long-term bonding protocols still must be established. Moreover, novel LDCs machinable blocks should be crystallized or heat-treated after milling for superior performance. CLINICAL SIGNIFICANCE: With more and newer etchable LDC materials entering the market, clinicians and technicians need to be aware of the differences in manufacturing and the resulting microstructure to ensure a successful treatment outcome that will last.
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Cerâmica , Porcelana Dentária , Cerâmica/química , Desenho Assistido por Computador , Porcelana Dentária/química , Teste de Materiais , Propriedades de SuperfícieRESUMO
Subcrestal placement of implants may have interproximal bone proximity issues that interfere with the submucosal contour of implant-supported zirconia restorations during delivery of the restorations. Modification of the mesial distal submucosal areas may be necessary to fully seat the restoration without impingement of the interproximal bone. Our aim was to determine if modification of submucosal cervical contour of implant supported zirconia-titanium base (Zi-Ti base) restorations resulted in a significant change in fracture strength compared with Zi-Ti base restorations without any modification near the cervical submucosal area. Implant Zi-Ti base restorations designed in the form of a maxillary premolar were made for the Straumann implant lab analog. Zirconia samples were cemented onto the Ti-base and the test group (N = 20) underwent recontouring and polishing at the junction of the Zi-Ti base cervical areas. The control group (N = 20) did not undergo any modifications. All 40 samples underwent fracture testing with an Instron machine. We assessed differences between modified and unmodified implants restorations using a 2-tailed t test for independent samples. Fracture strength values (N) ranged from 4354.68 to 6412.49 in the test group (N = 20) and from 5400.31 to 6953.22 in the control group (N = 20). The average fracture strength in the control group (6154.84 ± 320.50) was higher than in the modified group (5593.13 ± 486.51; P < .001). Modification of submucosal contour significantly decreased fracture strength. However, the average fracture strength exceeded the masticatory forces of humans.
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Coroas , Implantes Dentários , Dente Suporte , Projeto do Implante Dentário-Pivô , Porcelana Dentária , Falha de Restauração Dentária , Análise do Estresse Dentário , Humanos , Teste de Materiais , Titânio , ZircônioRESUMO
OBJECTIVES: To compare the shear bond strength (SBS) of the CAD/CAM material-bracket interface using three surface treatments: following manufacturers' instructions (MI), Monobond Etch & Prime (MEP) and 9.6% hydrofluoric acid plus silane (9.6% HF), after 24 h of water storage (24 h) and 10,000 cycles of thermocycling (TC). MATERIALS AND METHODS: A total of 126 crowns with four identical buccal surfaces were fabricated using seven different CAD/CAM materials: CEREC Blocs unglazed (CBU), CEREC Blocs glazed (CBG), IPS Empress CAD (EMP), IPS e.max CAD (EMA), VITA SUPRINITY PC (SUP), inCoris TZI (TZI) and VITA ENAMIC (ENA). A total of 504 APC Flash-Free (APC FF)-precoated brackets were bonded applying three surface treatments: (1) MI; (2) MEP and (3) 9.6% HF. SBS was performed after 24 h and TC. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). RESULTS: MEP conditioning yielded lower SBS results compared with MI and 9.6% HF for CBG (24 h and TC) and EMA (TC) materials. EMP conditioning with MEP after 24 h obtained lower SBS values compared with MI; however, after TC, SBS was similar to MI group and higher than with 9.6% HF. After TC for TZI ceramic, MI protocol (sandblasting) obtained higher SBS scores than MEP, but similar than 9.6% HF. Treatment of ENA with MI and MEP produced higher results than 9.6% HF after TC. SBS results were similar for CBU and SUP, regardless of the treatment. CONCLUSIONS: Although each CAD/CAM material requires specific surface treatment to obtain the highest SBS of APC FF brackets, the treatment with MEP is a valid orthodontic alternative for most of the materials tested. TC significantly decreased SBS for most of the materials. CLINICAL RELEVANCE: MEP can be considered a valid and promising product to condition most of the CAD/CAM ceramics evaluated for APC FF bracket bonding purposes, allowing a faster and safer procedure.
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Colagem Dentária , Braquetes Ortodônticos , Cerâmica , Desenho Assistido por Computador , Porcelana Dentária , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de SuperfícieRESUMO
STATEMENT OF PROBLEM: Components have been introduced that allow the screw channel of an implant crown to be angled lingually and the screws to be tightened in a non-axial direction to the implant. Information is lacking as to how the removal torque value (RTV) and force to failure (FTF) of these components compare with those of conventional screws. PURPOSE: The purpose of this in vitro study was to evaluate and compare the RTV and FTF values of cyclically loaded implant-supported restorations. Specifically, values for conventional axially tightened gold screws were compared with those for non-axially tightened screws aligned at 3 different angulations. MATERIAL AND METHODS: A total of 28 external hexagon implants were embedded in acrylic resin and divided into 4 groups. Simulated restorations were fabricated on abutments capable of different screw channel angulations. Dynamic abutments (DA) were waxed at different angulations and then cast. Simulated restorations were placed on the implants and tightened: group 0GS: 0-degree angulation gold screw tightened to 35 Ncm (control group); group 0DAS, 0-degree angulation with dynamic abutment (DAS) screw; group 20DAS: 20-degree angulation with DA screw; group 28DAS: 28-degree angulation with DAS screw. In groups 0DAS, 20DAS, and 28DAS, the DAS screw was used and tightened to 25 Ncm. Screw removal torque values were recorded by using a digital torque gauge at baseline and, after reaching cyclic fatigue, by using a dual-axis mastication simulator for 1200000 cycles. The fracture strength (FS) of the implant restorations was tested under compression until failure by using a universal testing machine. Differences between baseline and removal torque (ΔRT) were calculated. Statistical analysis was performed by using 1-way ANOVA for ΔRT and FS separately (α=.05). RESULTS: ΔRT and FS values were not significantly different among the groups (P>.05). The screw fractured in 5 of 28 specimens (17.8%); the remaining specimens failed with fracture of the implant. CONCLUSIONS: The removal torque and FS values of the angulated abutment screw were comparable to those of the gold screw. Angulation of the abutment had no significant influence on the screw removal torque values.
Assuntos
Parafusos Ósseos , Coroas , Implantes Dentários , Prótese Dentária Fixada por Implante , Falha de Restauração Dentária , Retenção em Prótese Dentária , Análise do Estresse Dentário , Ligas de Ouro , Técnicas In Vitro , Teste de Materiais , Titânio , TorqueRESUMO
STATEMENT OF PROBLEM: The joint adjacent to the cantilevered section of an implant-supported complete fixed dental prosthesis (ICFDP) undergoes the most stress because of force magnification in this area, making it more prone to mechanical failure. PURPOSE: The purpose of this in vitro study was to evaluate the ultimate force-to-failure distal to the terminal implant of a simulated ICFDP reinforced with glass fiber compared with that of a conventionally fabricated prosthesis. MATERIAL AND METHODS: Thirty ICFDPs with bilateral distal cantilevers were fabricated and divided into 3 groups: the not-reinforced (NR) group was processed without reinforcement, the glass-fiber-reinforced (GR) group was reinforced with glass fiber, and the titanium-reinforced (TR) group was fabricated with a titanium bar. The specimens were screw-retained onto a standardized mandibular model with 4-implant analogs embedded in acrylic resin. All groups were processed using heat-polymerized acrylic resin. After 24 hours, the cantilevers were loaded to fracture (in N) 10 mm away from the center of the most distal analog under compression at a crosshead speed of 1 mm/min. Statistical analysis of data was performed using a 1-way analysis of variance (ANOVA) model by using Tukey B post hoc comparison procedures (α=.05). RESULTS: Data revealed the mean fracture load of the NR group was 1073 ±108 N, 1400.75 ±123.53 N for the GR group, and 1652.78 ±274.14 N for the TR group. Statistically significant differences (P<.05) were found among all 3 groups. Comparison between the left and right side of the tested prostheses did not show any significant differences (P=.595). CONCLUSIONS: A fiber-reinforced ICFDP provides better biomechanical properties than an unreinforced one, which may allow its longer-term use as an interim ICFDP. However, the titanium bar ICFDP still provided the best resistance to fracture.
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Prótese Dentária Fixada por Implante , Falha de Restauração Dentária , Vidro , Estresse Mecânico , Planejamento de Prótese Dentária , Análise do Estresse DentárioRESUMO
OBJECTIVES: The purpose of this investigation was to analyze epidemiological patterns, clinical features and the management of odontogenic infections in patients undergoing treatment in a dental emergency outpatient care unit. STUDY DESIGN: A retrospective analysis of 58 161 case records of patients presenting to an emergency outpatient unit in Hamburg, Germany between 2000-2007 was performed. From this pool, patients with odontogenic infections were identified using an ICD-10 code, analyzing age, gender, medical co-morbidities, duration of pain, ratio of infiltrates/abscesses, affected teeth, management of infection and administered antibiotics. RESULTS: Of the 58 161 patients, 5357 (9.2%) were identified as having odontogenic infections, with 2689 (50.2%) inflammatory infiltrates and 2668 (49.8%) abscesses. Mean age was 34.8 ± 16.8 years. As the primary site of odontogenic infection, the most significantly affected teeth were the maxillary and mandibular first molars. Patients in age-group 20-29 years (25.1%) utilized the emergency care unit more frequently than other age groups. Clindamycin was the most frequently administered antibiotic. CONCLUSIONS: Early recognition, diagnosis and management of odontogenic infections are requisite for avoiding or minimizing the development of potential complications. Strategies and evidence-based protocols should be developed within the dental ambulatory care sector, advancing interdisciplinary cooperation between general dentists and oral or maxillofacial surgeons.
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Serviços de Saúde Bucal/organização & administração , Serviço Hospitalar de Emergência/organização & administração , Infecção Focal Dentária/terapia , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Infecção Focal Dentária/epidemiologia , Alemanha/epidemiologia , Humanos , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Adulto JovemRESUMO
This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p < 0.001). GC (22.4 MPa) and CSA (18.4 MPa) revealed the highest bond strengths in group SB. Bond strengths of self-adhesive resin cements to zirconia were increased by air-particle abrasion. Cements containing adhesive monomers (MDP/4-META) were superior to other compositions.
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Colagem Dentária , Corrosão Dentária/métodos , Porcelana Dentária/química , Cimentos de Resina/química , Zircônio/química , Ar , Resinas Compostas/química , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Metacrilatos/química , Compostos Organofosforados/química , Resistência ao Cisalhamento , Estresse Mecânico , Propriedades de Superfície , Temperatura , Fatores de TempoRESUMO
PURPOSE: To evaluate the bond strength of recently developed feldspathic veneering ceramics to zirconium-oxide ceramic core material (Y-TZP). In addition, the effect of thermocycling on the bond strength was investigated. METHODS: 90 square Lava framework Y-TZP specimens were randomly assigned to three groups (n = 30) and veneered with one of the three zirconia veneering ceramics Cerabien ZR (CZR), GC Initial (GCI), or Lava Ceram (LC). 30 additional metal-ceramic specimens served as the control (VO). 15 specimens per group were stored in a saline solution for 3 days. To test the durability of the bond, 15 specimens per group were thermocycled for 10,000 cycles between 5 degrees to 60 degrees C with a 15-second dwell time. Shear strength was tested with an Instron universal testing system. A two-way ANOVA model and Tukey's HSD were applied for statistical analyses (alpha = 0.05). RESULTS: The different material combinations revealed significantly different shear bond strength values (CZR > GCI > LC > VO). All veneering ceramic/zirconia combinations showed significantly higher bond strength than the metal-ceramic control VO. Bond strength values were not affected by thermocycling, except for CZR, which had significantly higher bond strength after thermocycling. Microscopic evaluation of failure modes revealed 100% cohesive failures in the veneering ceramic for all specimens.
Assuntos
Colagem Dentária , Materiais Dentários/química , Porcelana Dentária/química , Facetas Dentárias , Zircônio/química , Silicatos de Alumínio/química , Análise do Estresse Dentário/instrumentação , Ligas de Ouro/química , Humanos , Ligas Metalo-Cerâmicas/química , Compostos de Potássio/química , Resistência ao Cisalhamento , Cloreto de Sódio/química , Estresse Mecânico , Propriedades de Superfície , Temperatura , Fatores de Tempo , Ítrio/químicaRESUMO
Mammalian teeth primarily consist of two distinct calcified tissues, enamel and dentin, that are intricately integrated by a complex and critical structure, the dentin-enamel junction (DEJ). Loss of enamel exposes the underlying dentin, increasing the risk of several irreversible dental diseases. This paper highlights the significance of utilizing the functional domains of a major enamel matrix protein, amelogenin, intrinsic to tooth enamel and the DEJ interface, to rationally design smaller bioinspired peptides for regeneration of tooth microstructures. Using this strategy, we designed a synthetic peptide, P26, that demonstrates a remarkable dual mineralization potential to restore incipient enamel decay and mineralization defects localized in peripheral dentin below the DEJ. As a proof of principle, we demonstrate that interaction between P26 and collagen prompts peptide self-assembly, followed by mineralization of collagen fibrils in vitro. P26-mediated nucleation of hydroxyapatite (HAP) crystals on demineralized dentin in situ significantly facilitates the recovery of mineral density and effectively restores the biomechanical properties of dentin to near-native levels, suggesting that P26-based therapy has promising applications for treating diverse mineralized tissue defects in the tooth.
Assuntos
Colágeno , Dentina , Dente , Amelogenina , Animais , Peptídeos , Remineralização DentáriaRESUMO
BACKGROUND: Composite dental restorations are commonly used to restore cavitated carious lesions. Unfortunately, the main reason for failure is the development of secondary caries adjacent to the restoration. To improve the long-term survival of restorations, antibacterial agents have been added into dental materials. In this study, we assessed the antibacterial and bonding capacity of a commercial universal dental adhesive incorporated with the antibacterial agent tt-farnesol creating 3 experimental adhesives: 0.38% (v/v), 1.90% (v/v), and 3.80% (v/v), plus a control (no incorporation of tt-farnesol). METHODS: The antibacterial activity was evaluated by assessing colony-forming units (CFU), biofilm dry weight (DW) and production of extracellular insoluble polysaccharides (EIP) at day 2, 3, and 5 of biofilm growth post surface treatment on the surface of composite disks. The effect of tt-farnesol on the chemical and bonding capacity of the adhesive system was assessed via pH analysis, degree of conversion (DC), and microtensile bond strengths to human dentin in both self-etch and etch-and-rinse application modes. A qualitative analysis of the effects of tt-farnesol on biofilm formation was evaluated using scanning electron microscopy (SEM). The sealing capacity of all adhesive systems tested was evaluated using confocal laser scanning microscopy (CLSM). RESULTS: The 3.80% (v/v) experimental adhesive exhibited the lowest CFU count and lowest production of EIP at day 5. DW and pH values did no exhibit statistical differences among all tested groups. Bond strengths and DC decreased with the incorporation of the antibacterial agent into the adhesive system regardless of the concentration of tt-farnesol. CONCLUSION: The incorporation of tt-farnesol into the adhesive system significantly reduced bacterial viability and production of EIP; however, the bonding properties of the experimental dental adhesives were altered.
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OBJECTIVE: The purpose of this study was to evaluate the shear bond strength (SBS) of two dual-curing resin cements to two high-strength ceramics with different surface texture. MATERIAL AND METHODS: Composite cylinders were bonded to aluminum oxide (A) and zirconium oxide (Z) ceramic disks with six different surfaces. Investigated surfaces were for both ceramics: dry-pressed Procera Crown (A1, Z1), machined Procera Bridge (A2, Z2), airborne particle abraded Procera bridge (A3, Z3). Additional surfaces were, for alumina, dry-pressed Procera Laminate (A4) and, for zirconia, two modified surfaces (Z4, Z5). Two adhesive resin cements were used (Clearfil Esthetic and RelyX ARC). SBS was tested in a universal testing machine before and after artificial aging by thermal cycling. RESULTS: Mean SBS ranged from 6.1 to 38.4 MPa before and from 0.0 to 41.4 MPa after aging. Clearfil Esthetic in A3, A4, and Z3 performed better than RelyX ARC. Aging decreased SBS, except for Z1, Z4, and Z5. For alumina, A4 was higher in SBS than A2, but similar to A1 and A3. For zirconia, Z5 showed the highest SBS. Z4 was higher than Z2 and Z3, but similar to Z1. CONCLUSIONS: Shear bond strength to alumina and zirconia increases with surface roughness. The modified zirconia surface Z5 provides stable long-term shear bond strength and can be bonded to either of the two used cements.
Assuntos
Porcelana Dentária/química , Cimentos de Resina/química , Autocura de Resinas Dentárias/métodos , Óxido de Alumínio/química , Bis-Fenol A-Glicidil Metacrilato/química , Resinas Compostas/química , Corrosão Dentária/métodos , Materiais Dentários/química , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Ligas Metalo-Cerâmicas/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Resistência ao Cisalhamento , Estresse Mecânico , Propriedades de Superfície , Temperatura , Fatores de Tempo , Titânio/química , Água/química , Zircônio/químicaRESUMO
This report describes the clinical application of a new modified zirconia surface. Resin-bonded fixed partial dentures were fabricated for nonprepared abutments, cemented, and evaluated for retention and esthetics. Initial evaluation of this new modified zirconia surface reveals acceptable mechanical and esthetic properties.
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Anodontia/reabilitação , Porcelana Dentária , Falha de Restauração Dentária , Planejamento de Dentadura , Prótese Adesiva , Cimentação , Análise do Estresse Dentário , Retenção de Dentadura , Feminino , Humanos , Incisivo/anormalidades , Cimentos de Resina , Retratamento , Adulto Jovem , ZircônioRESUMO
STATEMENT OF PROBLEM: Successful long-term bonding to zirconia ceramic remains a challenge, requiring special cements and surface roughening by airborne-particle abrasion, which might negatively affect the ceramic. PURPOSE: The purpose of this study was to evaluate the shear bond strength (SBS) of composite resin cylinders to a modified zirconia surface using different luting techniques after thermal cycling. MATERIAL AND METHODS: Composite resin (TPH3) cylinders with a diameter of 3 mm were bonded to zirconia ceramics (Procera Zirconia) with a modified surface (RZ) and a machined surface (MZ). Three different adhesive luting cements (Panavia F2.0, RelyX ARC, RelyX Unicem) in combination with and without airborne-particle abrasion (50-microm and 110-microm Al(2)O(3)) were used. RZ was bonded using all 3 cements with (50 mum) and without airborne-particle abrasion; with 110 microm, only Panavia F2.0 was used. MZ was bonded using only Panavia F2.0 with (50 microm, 110 microm) and without airborne-particle abrasion. SBS was tested in a universal testing machine (Instron) before and after 90 days of water storage and 20,000 thermal cycles (dwell time, 15 seconds). Statistical analysis was performed using a multifactorial ANOVA model with alpha=.05. RESULTS: Mean SBS ranged from 10.1 to 20.0 MPa after 3 days and from 0.16 to 14.8 MPa after thermal cycling. Thermal cycling decreased SBS significantly. Airborne-particle abrasion significantly decreased SBS to the modified surface, regardless of cements used. SBS to the modified zirconia surface was significantly higher than to the machined surface. CONCLUSIONS: SBS to the modified zirconia surface is higher than to airborne-particle-abraded, machined zirconia. Airborne-particle abrasion of the modified zirconia surface is not recommended.
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Abrasão Dental por Ar , Colagem Dentária , Porcelana Dentária , Cimentos de Resina , Zircônio , Bis-Fenol A-Glicidil Metacrilato , Resinas Compostas , Análise do Estresse Dentário , Teste de Materiais , Polietilenoglicóis , Ácidos Polimetacrílicos , Resistência ao Cisalhamento , Propriedades de Superfície , Fatores de Tempo , ÁguaRESUMO
Noninvasive (preventive) measures involving fluoridation, dietary control, and oral hygiene instruction, as well as invasive restorative methods, are the standard treatment options for interproximal caries. Intermediate treatment options, similar to pit-and-fissure sealing on occlusal surfaces that has been shown to be effective in preventing and inhibiting caries, have not yet been established on interproximal surfaces. Recently, the application of resins on interproximal caries lesions has been studied and improved, leading to the development of new materials, which infiltrate and seal the carious lesion, improving the inhibition of caries progression. Clinical data show this new technique complements existing treatment options for interproximal caries by delaying the time point for a restoration and consequently closing the gap between noninvasive and invasive treatment options.
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Cariostáticos/uso terapêutico , Cárie Dentária/prevenção & controle , Resinas Sintéticas/uso terapêutico , Ação Capilar , Cariostáticos/química , Cárie Dentária/patologia , Esmalte Dentário/patologia , Progressão da Doença , Humanos , Resinas Sintéticas/química , Coroa do Dente/patologiaRESUMO
OBJECTIVE: Polymerization of light-cured resin-based materials is well documented; however, the intensity of the activating light can be reduced by passage through air, dental structure, or restoration compromising the physical properties of the restoration. The aim of this study was to evaluate the depth of cure of different light cured composite resins polymerized directly or transdental, through enamel and enamel/dentin tissues. MATERIAL AND METHODS: Five composite resins were selected for this experiment: SureFil SDR, Dentsply (SDR), Filtek Supreme Plus, 3M ESPE (FSP), Aelite LS, Bisco (ALS), Filtek LS, 3M ESPE (FLS), and TPH, Dentsply (TPH). Thirty specimens of each material were prepared with 2- or 4-mm thickness. The specimens were light-cured (Elipar 2500, 3M ESPE) for 40 sec using three different protocols: direct or transdental, through a disc of enamel with 1 mm of thickness, and a disc of enamel and dentin with 2 mm of thickness. Eight Vickers microhardness (VH) measurements were taken from each specimen, four on top and four on bottom surface (Micromet, Buehler, 100 g per 15 sec). Data was analyzed with ANOVA three-way, Tukey HSD post-hoc (α = .05). RESULTS: Bottom surfaces of specimens exhibited statistically significant lower Vickers microhardness than the top surfaces for all composite resin evaluated, regardless of the curing conditions, except for the SDR when direct light-cured. Transdental light curing through enamel/dentin layer, significantly decreased VH (P<0.05) on the bottom surface of all composite groups. CONCLUSION: The results of this study showed that light-curing attenuation of dental structures negatively affect the micro-hardness of composite resins.
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PURPOSE: To compare initial and sustained clinical response of 6% hydrogen peroxide whitening strips and a 19% sodium percarbonate film in a randomized controlled trial. METHODS: Informed consent was obtained, after which 72 subjects were randomized to 6% hydrogen peroxide whitening strips (Crest Whitestrips), 19% sodium percarbonate brush-applied gel that dries as a film (Crest Night Effects), or placebo brush-applied gel without peroxide. Efficacy (digital imaging) and safety (clinical examination and interview) were assessed after 2 weeks treatment, and again at up to eight post-treatment timepoints over an 18-month post-treatment period. RESULTS: For Deltab* (yellowness), end-of-treatment adjusted means +/- standard errors (SE) were -2.37 +/- 0.088 for the strip group, -1.36 +/- 0.091 for the film group, and -0.08 +/- 0.090 for the placebo group. For DeltaL* (brightness), end-of-treatment adjusted means +/- SE were 2.40 +/- 0.121 for the strip group, 1.47 +/- 0.125 for the film group, and 0.06 +/- 0.122 for the placebo group. Groups differed significantly (P< 0.02) at end-of-treatment and throughout post-treatment. All treatments were well-tolerated, both peroxide-containing systems exhibited appreciable color retention throughout the 18-month post-treatment period, and there were no meaningful, persistent adverse events seen with long-term follow-up.
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Carbonatos/uso terapêutico , Peróxido de Hidrogênio/uso terapêutico , Oxidantes/uso terapêutico , Clareamento Dental/instrumentação , Adolescente , Adulto , Carbonatos/administração & dosagem , Cor , Feminino , Seguimentos , Humanos , Peróxido de Hidrogênio/administração & dosagem , Processamento de Imagem Assistida por Computador/métodos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Oxidantes/administração & dosagem , Fotografia Dentária/métodos , Placebos , Segurança , Dente/patologia , Clareamento Dental/métodos , Descoloração de Dente/patologia , Descoloração de Dente/terapia , Resultado do Tratamento , Adulto JovemRESUMO
Zirconia is becoming increasingly used as a restorative material for implant-supported restorations; however, information is lacking with respect to the minimum thickness of zirconia surrounding the implant components. The purpose of this study is to evaluate the resistance to fracture of different thicknesses of zirconia luted to implant components. Thirty cylinders of zirconia (Prettau, Zirkonzahn) with 13-mm height, designed with indented occlusal surface for loading, and varying wall thicknesses (0.5 mm, 1 mm, 1.5 mm; n = 10/group) were milled using a computer-aided design/computer-aided manufacturing system (Modellier, Zirkonzahn), after which they were sintered. Titanium temporary cylinders (ITCS41, Biomet3i) were attached to 30 implant analogs (ILA20, Biomet3i) that were embedded into polymethylmethacrylate blocks (Palapress Vario, Heraeus Kulzer) with dimensions of 4.5 × 1.8 × 2 cm. Zirconia specimens were cemented to the titanium cylinders using a self-adhesive, dual-cure resin cement (Panavia SA, Kuraray). Load to failure test was performed under compression until fracture using a universal testing machine (Instron5965, Instron) at a crosshead speed of 0.5 mm/min and measured in N (Newton). Statistical analysis was performed using 1-way analysis of variance and Tukey B test at α = .05 (SPSS19, IBM). Mean load to failure was 1059.94 N, 2019.46 N, and 4074.79 N for groups 0.5 mm, 1 mm, and 1.5 mm, respectively. Values were significantly different between the groups (P < .05). Study limitations are that it is in vitro, specimens do not replicate tooth dimensions, and forces are static and directed toward the occlusal portion of each specimen. Within these limitations and considering the average human bite force, a thickness of 0.5 mm to 1 mm of this particular type of zirconia around this type of implant component can avoid fracture with these dimensions.
Assuntos
Desenho Assistido por Computador , Dente Suporte , Fraturas dos Dentes , Análise do Estresse Dentário , Humanos , Teste de Materiais , ZircônioRESUMO
OBJECTIVES: To determine the effects of intrinsic wetness on the formation of dentin bonding interfaces of four resin cement systems bonded to dentin under different pulpal pressures. METHODS: Thirty-six freshly extracted third molars were selected and processed for dentin µTBS. The teeth were randomly assigned into 12 experimental groups, according to the adhesive luting system [Adper Single Bond Plus (3M ESPE) combined with two luting agents RelyX ARC (3M ESPE) and heated Filtek Z250 Universal Restorative (3M ESPE), Clearfil CD Bond (Kuraray) combined with Clearfil Esthetic Cement (Kuraray), and RelyX Unicem 2 Automix (3M ESPE)] and pulpal pressure (0, 5, and 20 cm of simulated pulpal pressure). Leucite-reinforced glass-ceramic slabs (IPS Empress CAD, Ivoclar Vivadent) of 3mm thickness were bonded to dentin. The samples were stored in distilled water for 24h and then sectioned in X/Y directions across the adhesive interface to obtain specimens with a cross section of 0.8 ± 0.2mm(2). All sticks were fractured by tension at a crosshead speed of 1.0mm/min and the data were submitted to Kruskal-Wallis and Mann-Whitney Tests (α=0.05). Ultrastructural analysis of the interfaces was performed using Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM). RESULTS: The statistical analyses showed that pulpal pressure decreased µTBS for all groups. Significantly higher µTBS values were obtained in heated Z250 group restored without any pulpal pressure. CLSM showed that the uptake of water through the dentin tubuli and their anastomosis of lateral branches during the adhesive luting procedures prevented adequate formation of the dentin bonding interfaces. SEM showed that the luting film created is material- dependent and all adhesive failure occurred at the resin-dentin interface. CONCLUSION: The constant intrinsic wetness replenishment prevents adequate formation of the hybrid layer. CLINICAL SIGNIFICANCE: Intrinsic moisture during adhesive luting procedures significantly affects the interaction between luting materials and dentin subtract and decreases the quality and bonding strength of the resin-dentin bond.
Assuntos
Colagem Dentária , Adesivos Dentinários/química , Dentina/ultraestrutura , Cimentos de Resina/química , Água/química , Condicionamento Ácido do Dente/métodos , Bis-Fenol A-Glicidil Metacrilato , Cimentos Dentários/química , Análise do Estresse Dentário , Dentina/diagnóstico por imagem , Permeabilidade da Dentina/fisiologia , Humanos , Teste de Materiais , Dente SerotinoRESUMO
OBJECTIVES: The aim of this study was to evaluate the formation of dentin bonding interfaces using the water-wet and the ethanol-wet techniques under simulated pulpal pressure, and to assess the effect of adhesive solvent and thermomechanical loading. METHODS: Flat dentin surfaces were restored under 20mm-simulated pulpal pressure following two bonding approaches (water-wet and ethanol-wet bonding) in combination with dental adhesives containing ethanol (Single Bond Plus and Scotchbond Multi-Purpose) or acetone (One-Step Plus and All-Bond 2) as solvent. Half of the restorations of each subgroup were subjected to thermocycling followed by cyclic loading (three teeth per group). Bond strength was measured using the microtensile bond strength test and fitted to a Weibull distribution (α=0.05). Ultrastructural analyses of the interface and leakage/nanoleakage evaluation were performed using confocal scanning microscopy (CLSM) and transmission electron microscopy (TEM). RESULTS: Water permeation through dentin tubules during adhesive application prevented adequate penetration of adhesive monomers into the demineralized collagen matrix in both bonding techniques, but more severely for water-wet bonding. Acetone-solvated adhesives showed worse bonding performance and hybridization than ethanol-based systems when applied in the ethanol-wet mode, both before and after thermomechanical challenge. SIGNIFICANCE: The ethanol-wet bonding technique helps to compensate for water permeation from dentin tubules during the bonding procedures to form more stable dentin bonds, especially when used in conjunction to ethanol-solvated systems.