RESUMO
OBJECTIVE: The purpose of this study was to compare the optical and mechanical properties of newer ceramic CAD/CAM materials to more established materials on the market. METHODS AND MATERIALS: The following ceramic materials were tested: lithium disilicate/lithium-aluminum silicate (Tessera, Dentsply/Sirona), lithium disilicate (Initial LiSi Block, GC), IPS e.max CAD, Ivoclar Vivadent), and 4Y polycrystalline stabilized zirconia (IPS e.max ZirCAD MT, Ivoclar Vivadent; Katana STML, Kuraray; YZ ST, VITA). Optical properties (translucency, opalescence) were determined using a dental spectrophotometer on 0.5-, 1.0-, 1.5-, or 2.0-mm specimens. Mechanical properties (flexural strength, flexural modulus, flexural fatigue strength, Weibull modulus, and characteristic strength) were determined with beams undergoing 3-point bend testing. The data were analyzed with multiple analyses of variance and Tukey's post hoc tests (α=0.05). RESULTS: Significant differences were found between groups based on type of ceramic or property (p<0.05). CONCLUSIONS: In general, the lithium disilicate based-ceramic materials had greater optical properties and lower mechanical properties than the zirconia-based ceramic materials.
Assuntos
Cerâmica , Porcelana Dentária , Teste de Materiais , Propriedades de Superfície , Porcelana Dentária/química , Cerâmica/química , Zircônio/química , Desenho Assistido por ComputadorRESUMO
CLINICAL RELEVANCE: Mechanical surface roughening of the titanium-abutment base is necessary to increase the pull-off bond strength of the lithium disilicate abutment material. Additional chemical surface treatment may further increase the bond strength, but the effects are product specific.
Assuntos
Cerâmica , Titânio , Adaptação Psicológica , Porcelana Dentária , Teste de Materiais , Propriedades de SuperfícieRESUMO
A new nanofiber-reinforced hybrid composite (NovaPro Fill, Nanova) was recently introduced with reportedly improved mechanical properties. The purpose of this study was to compare the properties (flexural strength/modulus, degree of conversion [DC], depth of cure, and polymerization shrinkage) of the nanofiber composite to those of traditional hybrid composites (Filtek Z250, 3M ESPE; Esthet-X HD, Dentsply). To determine flexural strength and modulus, composite was placed in a rectangular mold, light-cured, stored for 24 hours, and then fractured in a universal testing machine. For degree of conversion, composite was placed in a cylindrical mold, light-cured, and stored for 24 hours. Measurements were made at the top and bottom surfaces using Fourier Transform Infrared Spectroscopy. To determine depth of cure, composite was placed in a cylindrical mold and light-cured. Uncured composite was scraped until polymerized resin was reached. Remaining composite was measured and divided by two. Polymerization shrinkage was determined by placing the composite material on a pedestal in a video-imaging device while light-curing. Shrinkage was determined after 10 minutes. Data were analyzed with one-way analysis of variance and Tukey post hoc test per property (α=0.05). Compared to Filtek Z250, NovaPro Fill had significantly lower flexural strength and modulus, greater volumetric shrinkage, and similar depth of cure, but greater top and bottom DC. Compared to Esthet-X HD, NovaPro Fill had similar flexural strength, shrinkage, and top and bottom DC, but significantly greater depth of cure and flexural modulus.
Assuntos
Resinas Compostas/química , Nanofibras/química , Módulo de Elasticidade , Resistência à Flexão , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Microscopia Eletrônica de Varredura , Polimerização , Propriedades de SuperfícieRESUMO
The purpose of this study was to compare the whitening efficacy of a novel bleaching agent containing a unique tribarrel hydremide-peroxide gel (KöR) with a traditional bleaching system of hydrogen peroxide or carbamide peroxide (Opalescence). Bovine incisors were mounted into a custom resin, arch-shaped mounting device. Four groups of 10 teeth were created using mounting devices containing five teeth each. The in-office and home bleaching gels of KöR and Opalescence were applied to the teeth alone and in trays to simulate a combination of in-office and home bleaching or home bleaching only. Spectrophotometer readings of L* a* b* were performed at baseline, the end of active bleaching (immediate), and three and six months postbleaching. Immediately postbleaching, the use of Opalescence gel resulted in greater change in ΔE* and Δb* (less yellow) for combined and home bleaching techniques compared with KöR. After six months, Opalescence had significantly greater ΔE* and Δb* compared with KöR for home bleaching only. There was no significant difference in ΔL* between Opalescence and KöR at any time period with either technique.
Assuntos
Clareadores Dentários/uso terapêutico , Clareamento Dental/métodos , Animais , Peróxido de Carbamida , Bovinos , Géis , Peróxido de Hidrogênio/uso terapêutico , Técnicas In Vitro , Peróxidos/uso terapêutico , Resultado do Tratamento , Ureia/análogos & derivados , Ureia/uso terapêuticoRESUMO
The carving of a complex amalgam restoration may occasionally result in light proximal contact with the adjacent tooth. The purpose of this study was to investigate the strength of complex amalgam restorations repaired with a proximal slot amalgam preparation. Extracted human third molars of similar coronal size were sectioned 1 mm apical to the height of the contour using a saw and were randomly distributed into 9 groups of 10 teeth each. One pin was placed at each line angle of the flattened dentinal tooth surface. A metal matrix band was placed and an admixed alloy was condensed and carved to create a full crown contour but with a flat occlusal surface. A proximal slot was prepared with or without a retention groove and repaired using a single-composition spherical amalgam 15 minutes, 24 hours, one week, or six months after the initial crown condensation. The specimens were stored for 24 hours in 37°C water before fracture at the marginal ridge using a round-ended blade in a universal testing machine. The control group was not repaired. The mean maximum force in newtons and standard deviation were determined per group. Data were analyzed with a 2-way analysis of variance as well as Tukey and Dunnett tests (α=0.05). Significant differences were found between groups based on type of slot preparation (p=0.017) but not on time (p=0.327), with no significant interaction (p=0.152). No significant difference in the strength of the marginal ridge was found between any repair group and the unrepaired control group (p>0.076). The proximal repair strength of a complex amalgam restoration was not significantly different from an unrepaired amalgam crown. Placing a retention groove in the proximal slot preparation resulted in significantly greater fracture strength than a slot with no retention grooves. Time of repair had no significant effect on the strength of the repair.
Assuntos
Amálgama Dentário/química , Preparo da Cavidade Dentária/métodos , Restauração Dentária Permanente/métodos , Materiais Dentários/química , Falha de Restauração Dentária , Análise do Estresse Dentário , Humanos , Técnicas In Vitro , Teste de Materiais , Dente Serotino , Fatores de TempoRESUMO
Newer bulk-fill composites claim a greater depth of cure than conventional resin-based composites. To facilitate complete curing, the manufacturer of SonicFill (Kerr) recommends curing from the occlusal, as well as the buccal and lingual, surfaces of the tooth. The purpose of this study was to quantify the degree of curing light attenuation as it passes through natural tooth structure, and how this attenuation affects the depth of cure of different posterior resin composites. Ten noncarious extracted mandibular third molars were sectioned to produce 5-mm-thick pieces of buccal tooth structure. Sanding 0.5-mm increments from the flattened surface produced 4.5-, 4.0-, 3.5-, 3.0-, 2.5-, 2.0-, and finally 1.5-mm-thick sections. A Bluephase G2 (Ivoclar) curing light with an 8-mm-diameter light guide set on high for 20 seconds was used for measurement of irradiance as it passed through different thicknesses of tooth structure and air. The average irradiance (mW/cm(2)) was measured with a MARC-RC Resin Calibrator with a 4-mm-diameter sensor (BlueLight Analytics). To measure depth of cure of a conventional hybrid composite (Herculite Ultra; Kerr) vs a bulk-fill hybrid composite (SonicFill) through varying thicknesses of tooth structure, composites were cured in a 4-mm-diameter × 10.25-mm-long split mold according to International Organization for Standardization 4049. A mean and standard deviation was determined per group. Data were analyzed with a one-way analysis of variance (ANOVA)/Tukey test and two-way ANOVA/Tukey test (α=0.05). One-way ANOVA/Tukey found a significant decrease in irradiance based on thickness of tooth structure or distance through air (p<0.001). Two-way ANOVA/Tukey found a significant decrease in depth of cure based on thickness of tooth structure (p<0.001) and on composite type (p<0.001) with no significant interaction (p=0.623). SonicFill had a significantly greater depth of cure than Herculite Ultra.
Assuntos
Resinas Compostas/química , Cura Luminosa de Adesivos Dentários , Dente Serotino/anatomia & histologia , Materiais Dentários/química , Humanos , Técnicas In Vitro , Teste de Materiais , Propriedades de SuperfícieRESUMO
PURPOSE: Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. METHODS AND MATERIALS: Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. RESULTS: A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p<0.001) and surface treatment (p<0.001) but not on time (p=0.943), with no significant interaction (p>0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. CONCLUSIONS: Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.
Assuntos
Condicionamento Ácido do Dente , Colagem Dentária/métodos , Adesivos Dentinários , Condicionamento Ácido do Dente/métodos , Análise de Variância , Esmalte Dentário , Análise do Estresse Dentário , Humanos , Técnicas In Vitro , Teste de Materiais , Dente Molar , Resistência ao CisalhamentoRESUMO
Amalgapins are susceptible to early fracture during matrix removal and carving. The purpose of this study was to examine the early fracture resistance of amalgapin-retained restorations using a spherical amalgam alloy, an admixed amalgam alloy, a combination of admixed alloy over the spherical alloy, and a recently introduced modified spherical amalgam alloy. Four amalgapin channels with a diameter of 1.4 mm and depth of 2 mm were prepared in cylinders of Macor, a machinable ceramic material. The amalgapins were hand condensed, and the bulk of the restoration was mechanically condensed. In the group using the combination of alloys, 800 mg of spherical alloy was condensed into the amalgapins and over the floor of the preparation. The admixed alloy was then condensed over the spherical alloy to build up the bulk of the restoration. Using an Instron Universal Testing Machine, the restorations were tested to shear failure at an average of 15.8 +/- 1.3 minutes after the initiation of trituration of the amalgam alloy. A metal ring was placed around the restoration and pulled 90 degrees to the long axis to simulate matrix band removal. Data were analyzed using Kruskal-Wallis procedures. The fracture resistance of the spherical alloy group and the spherical/admixed group were significantly higher than admixed or Tytin FC. All fractures occurred in amalgam at the entrance to the amalgapin channel. The combination of spherical and admixed amalgam alloys in a restoration may reduce the potential for early dislodgment while allowing additional time for carving.
Assuntos
Amálgama Dentário , Pinos Dentários , Falha de Restauração Dentária , Ligas Dentárias , Amálgama Dentário/química , Restauração Dentária Permanente , Análise de Falha de Equipamento , Teste de MateriaisRESUMO
Dentists are faced with clinical situations that require the decision to replace or repair an amalgam restoration. The purpose of this study was to compare five amalgam repair techniques. Six groups of 15 amalgam beams each were fabricated by mechanical condensation of Tytin into an anodized aluminum split mold. Specimens were aged for 7 days prior to repair. Repaired specimens were stored for 7 days and thermocycled 500 times. Repair strength was measured by transverse strength testing in an Instron testing machine. Data were analyzed by a one-way ANOVA and a Student-Newman-Keuls test at the P < or = 0.05 level. The surface treatments were: Group A) intact beams, B) roughened with a #557 bur, C) air abraded with 50 microns aluminum oxide, D) retentive undercuts with a #33 1/2 bur, E) Amalgambond Plus, and F) no treatment. The repair strength of the various experimental groups ranged from 7-18% of the intact specimens. The #557 bur-roughened group yielded statistically higher repair strengths than all other surface treatments, which were statistically equivalent to each other.
Assuntos
Amálgama Dentário , Reparação em Prótese Dentária/métodos , Óxido de Alumínio , Análise de Variância , Restauração Dentária Permanente , Teste de Materiais , Estresse Mecânico , Propriedades de Superfície , TermodinâmicaRESUMO
OBJECTIVE: This study evaluated the effect of preparation utilization and design, and addition of resin composite to the bonding interface, on the fracture resistance of reattached incisal fragments. METHOD AND MATERIALS: Sixty bovine incisors were distributed among 1 control group and 5 experimental groups. Experimental specimens were sectioned 3.0 mm from the incisal edge with a 0.15-mm wafering blade at a 25-degree inclination apically in a faciolingual direction. Two groups received no further preparation. Specimens in the other 3 groups received either external bevels, internal bevels, or combined external and internal bevels. One preparationless group was reattached with dentin bonding agent alone. All other fragments were reattached with a dentin bonding agent-resin composite interface. After thermocycling and 4 weeks of bond weathering, specimens were sheared to failure in a universal testing machine. RESULTS: No significant differences in fracture strength were observed among any of the experimental groups, yet each displayed significantly less resistance to fracture than the control group. Reattachment of fragments in all groups restored approximately one half or one third the fracture strength of the control teeth for crown or root fractures, respectively. CONCLUSION: Compared to the simple, expedient regimen of using a dentin bonding agent alone, nonconservative tooth modification and the addition of resin composite to the bonding interface did not increase resistance to fracture and thus provided no retentive advantage.
Assuntos
Incisivo/lesões , Coroa do Dente/lesões , Fraturas dos Dentes/terapia , Preparo do Dente/métodos , Animais , Bovinos , Colagem Dentária , Adesivos Dentinários , Cimentos de Resina , Fraturas dos Dentes/prevenção & controle , Preparo do Dente/instrumentaçãoRESUMO
Approximately 18 percent of all permanent teeth have Class V lesions. In addition, the prolonged retention of teeth in an increasingly older population is expected to increase the prevalence of Class V lesions. Much has been written about the merits of various techniques for restoring such lesions, but little information is available comparing and contrasting all the material and procedural options available to the general dentist. Etiologies, indications for treatment, and restorative materials are discussed to provide guidance in planning treatment. A diagnostic decision tree is proposed for this dynamic area of restorative dentistry.
Assuntos
Restauração Dentária Permanente/métodos , Cárie Dentária/terapia , Materiais Dentários , Falha de Restauração Dentária , Sensibilidade da Dentina/terapia , Estética Dentária , Guias como Assunto , Humanos , Abrasão Dentária/terapia , Erosão Dentária/terapiaRESUMO
A case is presented of a pediatric patient with Turner syndrome. The presence of multiple carious teeth, a cardiovascular abnormality and the need for prophylactic antibiotics necessitated full mouth dental rehabilitation with the use of general anesthesia. Medical and dental complications, as well as options, are discussed.
Assuntos
Assistência Odontológica para Doentes Crônicos , Cárie Dentária/terapia , Síndrome de Turner , Ampicilina/uso terapêutico , Valva Aórtica/anormalidades , Criança , Endocardite Bacteriana/prevenção & controle , Feminino , Gentamicinas/uso terapêutico , Humanos , Má Oclusão Classe I de Angle/etiologia , Pré-Medicação , Síndrome de Turner/complicaçõesRESUMO
The purpose of this study was to compare the shear bond strengths to dentin of two dual-cure resin cements, one with a unique initiator, NX3 (Kerr Corp), and the other with a traditional redox-initiator system, Calibra (Dentsply), when used in combination with simplified or nonsimplified adhesive agents. The two dual-cure resin cements, in either self- or dual-cure activation modes, were bonded to human dentin with four dental adhesives to create 16 subgroups of 10 specimens each. After 24 hours of storage in distilled water at 37°C, the specimens were tested in shear in a universal testing machine. With both NX3 and Calibra, bond strengths significantly increased when the specimens were dual cured. In addition, with either cement in either mode, the nonsimplified adhesives performed significantly better than did the simplified adhesive bonding agents. When used specifically with simplified adhesives in either cure mode, NX3 did not produce significantly higher bond strengths than did Calibra. In general, lower dentin bond strengths were found with simplified adhesives or self-cure activation with either resin cement.
Assuntos
Resinas Compostas , Cimentos Dentários , Dentina , Teste de MateriaisRESUMO
Lowering the pH of sodium hypochlorite has been shown to greatly improve its efficacy as a disinfectant for irreversible hydrocolloid. This study evaluated the surface roughness and detail reproduction of gypsum casts recovered from impressions disinfected with sodium hypochlorite at altered pH levels. The experimental disinfectants were sodium hypochlorite 0.525% (10-minute immersion) at pH 11.5 (unaltered), pH 10, and pH 8. An additional group was tested at pH 10 for 5 minutes. There was a trend toward increased surface roughness as the pH was lowered, but a 5-minute immersion of impressions in sodium hypochlorite at pH 10 produced casts of equivalent surface roughness to impressions rinsed in water and poured immediately. The test for surface detail reproduction produced similar results.
Assuntos
Desinfetantes de Equipamento Odontológico/química , Desinfecção/métodos , Modelos Dentários , Hipoclorito de Sódio/química , Análise de Variância , Sulfato de Cálcio/química , Coloides/química , Materiais para Moldagem Odontológica/química , Técnica de Moldagem Odontológica/instrumentação , Estudos de Avaliação como Assunto , Concentração de Íons de Hidrogênio , Compostos Orgânicos , Reprodutibilidade dos Testes , Propriedades de Superfície , Fatores de TempoRESUMO
This study investigated the effects of various immersion times and concentrations of sodium hypochlorite on irreversible hydrocolloid impressions and resultant gypsum casts. Irreversible hydrocolloid impressions of a test die were immersed for 1, 5, or 10 minutes in water (control), 5.25%, 0.525%, and 0.0525% sodium hypochlorite and then cast in a Type III stone and a Type V stone. Each stone specimen was evaluated for detail reproduction, dimensional change, surface roughness, and surface hardness. The results indicated that impressions may be immersed in sodium hypochlorite for any of the experimental times and concentrations without negative effects on Type V stone casts. However, immersion of impressions in 5.25% sodium hypochlorite causes some surface deterioration on Type III stone casts.