RESUMO
OBJECTIVE: The aim of this scoping review was to analyze the available evidence on the preheating process and its effects on physicochemical properties of composite resins. MATERIALS AND METHODS: A systematic search was performed in August 2021 using PubMed/Medline, Embase, Scopus, and ISI Web of Science databases and gray literature without language or date restriction. Inclusion criteria were in vitro studies that assessed the physicochemical properties and marginal adaptation of preheated composite. Exclusion criteria were studies with experimental composite, literature reviews, clinical studies. Data from selected studies were qualitatively analyzed. RESULTS: In total, 104 studies were found from which 39 were included. The most used composite resin was Filtek Z350 XT (3 M/ESPE), preheated at 68°C in a Calset device (AdDent Inc., Danbury, CT, USA) for 5 or 15 min. Most studies showed decreased viscosity, increased conversion degree and microhardness of composite resins, and better marginal adaptation of direct and indirect restorations. Also, flexural strength was not affected, and data about bond strength were inconclusive due to heterogeneity among studies. CONCLUSION: The parameters used for preheating composite resins are heterogeneous. Preheating decreased viscosity, increased the conversion degree and microhardness of composite resins, and improved the marginal adaptation of direct and indirect restorations. CLINICAL SIGNIFICANCE: The analysis of evidence showed a high heterogeneity among preheating protocols. Preheating may benefit the handling and physicochemical properties of composite resins.
Assuntos
Resinas Compostas , Resistência à Flexão , Resinas Compostas/química , Teste de Materiais , ViscosidadeRESUMO
PURPOSE: To determine and compare the microstructure, flexural strength, flexural modulus, fracture strength, and microhardness of four types of computer-aided design/computer-aided manufacturing (CAD/CAM) materials for monolithic dental restorations. MATERIALS AND METHODS: A lithium disilicate (LD; IPS e.max CAD), a zirconia-reinforced lithium silicate (ZLS; VITA Suprinity), a hybrid high-performance polymer (HPP) composite resin (GC Cerasmart), and a hybrid polymer-infiltrated ceramic network (PICN) material (VITA Enamic) were used to manufacture monolithic ceramic posterior crowns (n = 10) that were adhesively cemented on resin-based composite dies and loaded until fracture. In addition, 40 rectangular bars (n = 10) were milled and polished for three-point flexural strength testing. Microhardness (Vickers indentation), as well as quantitative (energy dispersive spectroscopy) and qualitative (scanning electron microscopy) structural analysis were conducted on fracture surfaces. Data were analyzed by one-way ANOVA and Tukey HSD post-hoc test (p = 0.05). RESULTS: Mechanical testing results showed that the material type has a significant effect on the fracture strength (p < 0.0001) of the monolithic crowns with ZLS and LD presenting significantly higher fracture strength than the PICN and HPP hybrid materials. LD showed the highest flexural strength (p < 0.0001) followed by ZLS, HPP, and PICN, respectively. The lowest flexural modulus and hardness were presented by HPP whereas ZLS had the highest flexural modulus and hardness. The LD presented the highest modulus of resilience and the PICN the lowest. CONCLUSIONS: All CAD/CAM crown materials exhibited high values of fracture and flexural resistance, making them suitable materials for posterior full-crown restorations. Glass-ceramics suffered more from catastrophic and nonreparable fracture patterns, whereas minimal chipping and type II fracture patterns were more common in hybrid materials. The combination of more flexibility, less stiffness, and increased softness with satisfactory flexural and fracture strength values observed in PICN and HPP makes these two hybrid materials suitable choices for chairside monolithic crown fabrication.
Assuntos
Desenho Assistido por Computador , Coroas , Materiais Dentários , Planejamento de Prótese Dentária/métodos , Restauração Dentária Permanente , Cerâmica , Resinas Compostas , Materiais Dentários/química , Porcelana Dentária , Restauração Dentária Permanente/métodos , Análise do Estresse Dentário , Resistência à Flexão , Dureza , Humanos , Microscopia Eletrônica de VarreduraRESUMO
The aim of this study was to develop and characterise a new plasma-enhanced chemical vapor deposition (PECVD) film for improving shear bond strength (SBS) between yttria-stabilised tetragonal zirconia (Y-TZP) and veneering ceramic. In total, 192 Y-TZP samples (13â¯×â¯5.4â¯×â¯5â¯mm) were divided into 6 groups: control - no treatment (C), airborne-particle abrasion with 27⯵m aluminum oxide particles (Al27), 110⯵m aluminum oxide particles (Al110), and 250⯵m aluminum oxide particles (Al250), application of liner for zirconia (L) and the PECVD film application (P). The Y-TZP surface was characterised by means of Scanning Electronic Microscopy (SEM), Energy-dispersive Spectroscopy (EDS), atomic force microscopy (AFM), surface profilometry and surface-free energy (SFE). SBS between Y-TZP and veneering ceramic was tested before and after thermocycling (20,000â¯cycles of 5 and 55⯰C), and failure mode was also evaluated. Data were analysed by ANOVA and Tukey's HSD test (αâ¯=â¯0.05). Data analysis showed that PECVD film had no effect on surface roughness of Y-TZP (pâ¯>â¯0.05 vs control), whilst the other groups presented higher roughness values (pâ¯<â¯0.05). All treatments increased SFE, except the Al27 group. The highest SBS was presented by the P group (pâ¯<â¯0.05), and values were similar to those of the Al27 group (pâ¯=â¯0.107). Mixed failures were prevalent in all groups, and premature failures were found only in Al groups after thermocycling. Whilst PECVD treatment did not affect Y-TZP surface roughness, high SBS between Y-TZP and the veneering layer was observed. Therefore, PECVD treatment is a promising alternative to improve the performance of bi-layer zirconia-based restorations.
Assuntos
Cerâmica/química , Facetas Dentárias , Gases em Plasma/química , Resistência ao Cisalhamento , Zircônio/química , Porcelana Dentária/química , Propriedades de Superfície , Ítrio/químicaRESUMO
The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37 °C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey's test (P = .05) indicated that monolithic zirconia crowns presented similar fracture strength (PM = 3476.2 N ± 791.7; GM = 3561.5 N ± 991.6), which was higher than bilayer crowns (2060.4 N ± 810.6). There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.