Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
J Esthet Restor Dent ; 2020 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-33206440

RESUMEN

OBJECTIVE: The objective of this review is to present a synopsis of the existing clinical and in vitro evidence regarding placement of direct class II restorations with dental composites of varying viscosities, focusing on the marginal integrity achievable. OVERVIEW: The literature on class II composites placed with various techniques was searched through PubMed, Scopus, and the citations of identified articles, focusing on aspects related to adaptation and clinical performance. Studies comparing layering of conventional composite to layering with a flowable liner, including the "snow plow technique," use of warmed composite, flowable bulk-fill liners with a conventional composite capping layer, and bulk-fill restorative in a single or incremental fill (including placement with sonic energy and dual-curing) CONCLUSIONS: In vitro and clinical evidence does not support any one specific method or material type for achieving optimal performance when restoring class II cavity preparations with current dental composites. CLINICAL SIGNIFICANCE: Although there are many available placement methods and types of composite materials on the market for use in class II restorations, the reasonable success presented in the clinical and laboratory literature for the various approaches suggests that the most important factor for achieving success is likely careful and proper placement and light-curing technique, independent of the approach.

2.
J Am Dent Assoc ; 2020 Nov 26.
Artículo en Inglés | MEDLINE | ID: mdl-33250170

RESUMEN

BACKGROUND: Zirconia is a relatively new dental material used for indirect dental restorations. Little is known about how dental practitioners are using this material in their practice. METHODS: A survey on zirconia restorations was developed and administered electronically through e-mail communications to the American Dental Association Clinical Evaluators (ACE) Panel on August 31, 2020. Reminders were sent to nonrespondents, and the survey closed 2 weeks after the launch date. RESULTS: When using zirconia for a restoration, respondents choose it to restore natural teeth (99%) more often than implants (76%). Almost all respondents (98%) use it for posterior crowns, whereas approximately two-thirds (61%) use it for anterior crowns. Restoration removal or replacement and shade matching and translucency were the top 2 cited disadvantages of zirconia, whereas most of the respondents (57%) cited flexural strength or fracture resistance as the biggest advantage. Fine diamonds and ceramic polishers are used most often to polish and adjust zirconia restorations, whereas coarse diamond rotary instruments and those made specifically for zirconia are most frequently used for removing these restorations. Compared with metal ceramic restorations, more than 50% of respondents experience debonding more often with zirconia restorations. CONCLUSIONS: Dentists recognize the favorable fracture resistance and flexural strength properties of zirconia, and most use similar techniques when adjusting and removing this material. Removing these restorations and shade matching are a struggle for many. PRACTICAL IMPLICATIONS: Dentists may benefit from tips on the best methods to remove, shade match, and adhesively bond zirconia restorations.

3.
Compend Contin Educ Dent ; 41(9): 477-482, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33001658

RESUMEN

Lithium disilicate and layered zirconia appear to be the most prevalent materials used for single-unit anterior crowns. These materials offer the necessary mechanical properties as well as sufficient optical characteristics needed in this type of restoration. There now are also more translucent versions of zirconia available that can be used for monolithic anterior restorations. This article discusses the factors that clinicians must take into account when determining a restorative material for single-unit anterior crowns. Considerations for lithium-disilicate crowns, 4 and 5 mol% yttria-containing (4Y and 5Y) zirconia materials, and layered 3Y zirconia restorations are provided.


Asunto(s)
Coronas , Diente , Materiales Dentales , Ensayo de Materiales
4.
J Am Dent Assoc ; 151(10): 796-797.e2, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32979959

RESUMEN

BACKGROUND: Bonding crowns and bridges with resin cement can improve retention and reinforcement of the restoration. However, there is variation in the steps taken by different practitioners to achieve this goal. METHODS: The authors developed a survey on bonding dental crowns and bridges with resin cement and distributed it electronically to the American Dental Association Clinical Evaluators (ACE) Panel on May 22, 2020. The survey remained open for 2 weeks. Descriptive data analysis was conducted using SAS Version 9.4. RESULTS: A total of 326 panelists responded to the survey, and 86% of respondents who place crowns or bridges use resin cements for bonding. When placing a lithium disilicate restoration, an almost equal proportion of respondents etch it with hydrofluoric acid in their office or asked the laboratory to do it for them, and more than two-thirds use a silane primer before bonding. For zirconia restorations, 70% reported their restorations are sandblasted in the laboratory, and 39% use a primer containing 10-methacryloyloxydecyl dihydrogen phosphate. One-half of respondents clean their lithium disilicate or zirconia restorations with a cleaning solution. Resin cements used with a primer in the etch-and-rinse mode are the most widely used. The technique used to cure and clean excess resin cement varies among respondents. CONCLUSIONS: The types of resin cements used, tooth preparation, crown or bridge preparation, and bonding technique vary among this sample. PRACTICAL IMPLICATIONS: Although many dentists bond crowns and bridges on the basis of best practices, improvement in the process may be achieved by dentists communicating with their laboratory to confirm the steps performed there, ensuring an effective cleaning technique is used after try-in and verifying that the correct primer is used with their chosen restorative material.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , American Dental Association , Coronas , Cementos Dentales , Materiales Dentales , Porcelana Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Propiedades de Superficie , Encuestas y Cuestionarios , Estados Unidos
5.
J Esthet Restor Dent ; 32(8): 791-796, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32820865

RESUMEN

OBJECTIVES: To compare the ability of resin-modified glass ionomer (RMGI) and bioactive cements to prevent root dentin demineralization. MATERIALS AND METHODS: Fifty molars were prepared at the cementum-enamel junction (n = 10) and restored with three bioactive cements (Activa Bioactive Cement, ACT; Ceramir Crown and Bridge, CER; and Theracem, THE), a self-adhesive resin cement (Rely X Unicem 2, UNI), and a RMGI cement (Rely X Luting Plus, LUT). Specimens were cycled for 30 days between a demineralization solution (pH = 4) composed of 0.1 M lactic acid and 3 mM Ca3 (PO4 )2 for 4 hours and a remineralization solution (pH = 7.0) composed of 1.5 mM Ca, 0.9 mM P, and 20 mM Tris(hydroxymethyl)-aminomethane for 20 hours. Specimens were sectioned to 100 µm and evaluated with polarized light microscopy. A line was drawn parallel with the zone of demineralization for each tooth. The areas of "inhibition" (external to the line) were measured as positive values and "wall lesions" (pulpal to the line) were measured as negative areas. RESULTS: Significant differences were found between materials for "inhibition/wall lesion" areas in root dentin (P < .001) and ranked as (µm2 , mean ± SD): LUT (7700 ± 2500) > CER (3800 ± 1900), THE (2100 ± 2600), and ACT (1400 ± 700) > UNI (-2000 ± 1700). CONCLUSIONS: Bioactive cements showed net areas of demineralization inhibition albeit at a lower level than a reference RMGI cement. CLINICAL SIGNIFICANCE: RMGI or bioactive cements may be indicated for patients at risk of secondary caries around crown margins.

6.
J Am Dent Assoc ; 151(7): 544-545.e2, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32498964

RESUMEN

BACKGROUND: The ability to polymerize light-activated dental materials with dental light-curing units (DLCUs) has revolutionized dentistry. However, proper DLCU use is essential for ensuring the effectiveness and performance of these materials. METHODS: The authors developed an electronic cross-sectional survey in the American Dental Association Qualtrics Research Core platform. The survey included questions about DLCU use, unit type and selection, training, maintenance, technique, and safety measures. The authors deployed the survey to 809 American Dental Association Clinical Evaluators (ACE) panelists on October 9, 2019, and sent reminder links to nonrespondents 1 week later. They conducted exploratory and descriptive analyses using SAS software Version 9.4. RESULTS: Of the 353 ACE panelists who completed the survey, most used a DLCU in their practices (99%), and light-emitting diode multiwave units were the most common type of DLCU units (55%). Dentists use DLCUs for over one-half of their appointments each day (mean [standard deviation], 59% [22%]). Regarding technique, respondents reported that they modify their curing technique on the basis of material thickness (79%) and material type or light tip-to-target distances (59%). Maintenance practices varied, with two-thirds of respondents reporting that they periodically check their DLCUs' light output. CONCLUSIONS: DLCUs are an integral part of a general dentist's daily practice, but maintenance, ocular safety, and technique varied widely among this sample. PRACTICAL IMPLICATIONS: Because clinical effectiveness requires delivery of an adequate amount of light energy at the appropriate wavelength, variation in DLCU maintenance, safety, and techniques suggest that dentists could benefit from additional guidance and training on DLCU operation.


Asunto(s)
Resinas Compuestas , Luces de Curación Dental , American Dental Association , Estudios Transversales , Encuestas y Cuestionarios , Estados Unidos
7.
J Am Dent Assoc ; 151(4): 303-304.e2, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32222178

RESUMEN

BACKGROUND: Human papillomavirus (HPV) is a sexually transmitted oncovirus associated with several malignancies, including oropharyngeal squamous cell carcinoma. The 9-valent HPV vaccine can help protect against the high-risk HPV strains most commonly associated with HPV-related cancers. METHODS: The authors used an electronic survey to assess the roles of dentists and their team members in discussing the HPV vaccine, as well as administering the vaccine in a dental setting. On December 6, 2019, the authors e-mailed a survey link to the American Dental Association Clinical Evaluators (ACE) Panel (n = 813), a sample of American Dental Association member dentists. After 1 e-mail reminder, the survey closed on December 19, 2019, and the authors conducted exploratory and descriptive data analyses using SAS Version 9.4 (SAS). RESULTS: A total of 329 dentists responded to the survey, and 83 (25%) of them reported that they or their team members discuss the implications of the HPV vaccine with age-eligible patients or their parents or guardians. Dentists lead two-thirds (n = 218) of the discussions, and the clinical examination is the most frequent moment during the patient visit in which HPV-related topics are discussed. Some of the top reasons respondents mentioned for not discussing the vaccine in their practice were the perception that these discussions are best left to other health care professionals and not knowing how to address the topic with patients. If the scope of dental practice is expanded to include administering the vaccine, 125 (38%) of respondents would feel uncomfortable administering the vaccine. The most common potential barriers to administering the vaccine in a dental setting include obtaining reimbursement and vaccine management and preservation. CONCLUSIONS: The survey results suggest that dentists' comfort levels and perceived roles in discussing and administering the HPV vaccine vary. PRACTICAL IMPLICATIONS: There is a need to further define the role of dentists and their team members in the promotion and administration of the HPV vaccine. Resources for dentists and dental team members may be helpful to support professional education and communication about the HPV vaccine.


Asunto(s)
Infecciones por Papillomavirus , Vacunas contra Papillomavirus , American Dental Association , Conocimientos, Actitudes y Práctica en Salud , Humanos , Encuestas y Cuestionarios , Estados Unidos
8.
J Prosthet Dent ; 124(4): 488-493, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31952860

RESUMEN

STATEMENT OF PROBLEM: The use of dissimilar materials for opposing complete-mouth implant-supported prosthesis has become popular, especially when one arch is made from anatomical contour zirconia. However, the amount of wear zirconia causes on resin and other denture tooth materials is largely unknown. PURPOSE: The purpose of this in vitro study was to determine the volumetric wear of 4 commercially available resin materials used for denture teeth in complete-arch implant-supported prostheses opposed by zirconia. MATERIAL AND METHODS: A total of 32 maxillary central incisor denture teeth were evaluated (n=8): double crosslinked polymethyl methacrylate (PMMA) (DCL), nanohybrid composite resin (PHO), and computer-aided design and computer-aided manufacturing (CAD-CAM)-fabricated teeth made from crosslinked PMMA (TEL) and acrylate polymer (ZCAD). Antagonist cone-shaped specimens were milled from zirconia. Specimens were mounted in acrylic resin, polished to a flat surface by using 1200-grit SiC paper, and stored in water (37 °C for 24 hours) before exposure in a custom dual-axis wear simulator for 200 000 cycles with a vertical load of 20 N, a horizontal slide of 2 mm, and a frequency of 1 Hz. Volumetric wear was measured by using a noncontact profilometer and a superimposition software program. Data were analyzed with a 1-way analysis of variance (ANOVA) and the Tukey Honestly Significant Difference (HSD) post hoc test (α=.05). RESULTS: A statistically significant difference in volumetric wear was found between groups (P<.001), with PHO (4.3 ±1.0 mm3)

Asunto(s)
Alisadura de la Restauración Dental , Circonio , Resinas Compuestas , Ensayo de Materiales , Propiedades de Superficie
9.
J Esthet Restor Dent ; 32(2): 219-225, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31515932

RESUMEN

OBJECTIVES: To compare the strength and translucency of CAD/CAM zirconia blocks, with traditional and high-speed sintering, to lithium disilicate. MATERIALS AND METHODS: Three zirconia materials (Katana STML Block, Prettau Anterior, and Zpex Smile) were tested with either traditional (7 hours) or high-speed (18 or 30 minutes in a SpeedFire furnace) sintering. A lithium disilicate material (IPS e.max CAD) was tested as a reference. Three-point bend flexural strength specimens (16 mm × 4 mm × 1.2 mm, n = 10) were tested on 14-mm-separated supports and loaded to failure at 1 mm/min. Specimens (1 mm thick, n = 10) were measured in a Color-i7 spectrophotometer against a black and white background to calculate translucency parameter. Zirconia specimens were thermally etched and a grain structure was observed with scanning electron microscopy. Data were analyzed with 1-way ANOVA and Tukey's post hoc analysis (α = 0.05). RESULTS: There were significant differences between materials for flexural strength, translucency parameter, and grain size (P < .001). Grains became significantly larger and pores were present when two of the zirconia materials (Prettau Anterior and Zpex Smile) were sintered with a high-speed sintering program. CONCLUSIONS: Two of the zirconia materials (Prettau Anterior and Zpex Smile) became less translucent and less strong using a high-speed sintering program, whereas another (Katana STML Block) was unaffected.


Asunto(s)
Materiales Dentales , Circonio , Cerámica , Porcelana Dental , Ensayo de Materiales , Propiedades de Superficie
10.
J Prosthet Dent ; 123(5): 701-709, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-31590974

RESUMEN

STATEMENT OF PROBLEM: The definitive impression for a single-unit crown involves many material and technique factors that may affect the success of the crown. PURPOSE: The purpose of this prospective cohort study was to determine whether impression technique (tray selection), impression material, or tissue displacement technique are associated with the clinical acceptability of the crown (CAC). MATERIAL AND METHODS: Dentists in the National Dental Practice-Based Research Network documented details of the preparation, impression, and delivery of 3730 consecutive single-unit crowns. Mixed-effects logistic regression analyses were performed to evaluate associations between impression techniques and materials and the CAC and to assess associations between the presence of a subgingival margin with the displacement technique and the outcome variables CAC and number of impressions required. RESULTS: Of the 3730 crowns, 3589 (96.2%) were deemed clinically acceptable. A significant difference in the CAC was found with different impression techniques (P<.001) and different impression materials (P<.001). The percentage of the CAC for digital scans was 99.5%, 95.8% for dual-arch trays, 95.2% for quadrant trays, and 94.0% for complete-arch impression trays. Although no statistically significant difference was found in the CAC produced with dual-arch trays without both mesial and distal contacts, crowns fabricated under these conditions were less likely to achieve excellent occlusion. The percentage of the CAC for digital scans was 99.5%, 97.0% for polyether impressions, 95.5% for polyvinyl siloxane impressions, and 90.5% for other impression materials. Accounting for the location of the margin, the use of a dual-cord displacement technique was significantly associated with lower rates of requiring more than 1 impression (P=.015, odds ratio=1.43). CONCLUSIONS: Dual-arch trays produced clinically acceptable crowns; however, if the prepared tooth was unbounded, the occlusal fit was more likely to have been compromised. Digital scans produced a slightly higher rate of CAC than conventional impression materials. The use of a dual-cord technique was associated with a decreased need to remake impressions when the margins were subgingival.


Asunto(s)
Técnica de Impresión Dental , Diente , Coronas , Materiales de Impresión Dental , Modelos Dentales , Estudios Prospectivos
11.
Compend Contin Educ Dent ; 40(8): 508-513; quiz 514, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31478697

RESUMEN

Intraoral air abrasion is a technique in which abrasive particles are used to remove or alter tooth structure. Intraoral air-abrasion devices are available as standalone units that offer a variety of customization, such as modifications to air pressure, particle flow rate, and water flow rate, or as attachments to a dental unit, allowing for a smaller footprint in the operatory. Some devices used for intraoral air abrasion are able to limit excess particle spray through utilization of a shroud of water. Aluminum oxide, or alumina, is the most commonly used and most abrasive type of air-abrasion medium; it is used mostly to roughen or remove tooth structure. Other types of particles are intended for cleaning tooth surfaces. Previous research has reported negative and positive effects, as well as no effect, of air abrasion on the bond to dentin and enamel. The results of a study performed for this review show that air abrasion to both dentin and enamel with alumina at 60-psi pressure produced a visible roughening texture but did not negatively affect bond strength. Clinical applications for intraoral air abrasion in restorative dentistry include cavity preparation, cleaning of preparations, and removal of plaque and stain prior to restoring a tooth.


Asunto(s)
Abrasión Dental por Aire , Preparación de la Cavidad Dental , Óxido de Aluminio , Esmalte Dental , Dentina , Ensayo de Materiales , Propiedades de Superficie
12.
J Prosthodont ; 28(6): 659-665, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31145492

RESUMEN

PURPOSE: To determine if surface treatment and cement selection for traditional 3 mol% yttria partially stabilized zirconia (3Y-PSZ), "translucent" 5 mol% yttria-stabilized zirconia (5Y-Z), or lithium disilicate crowns affected their fracture load. MATERIALS AND METHODS: Crowns with 0.8 mm uniform thickness (96, n = 8/group) were milled of 3Y-PSZ (Lava Plus), 5Y-Z (Lava Esthetic), or lithium disilicate (e.max CAD) and sintered/crystallized. Half the crowns were either particle-abraded with 30 µm alumina (zirconias) or etched with 5% hydrofluoric acid (lithium disilicate), and the other half received no surface treatment. Half the crowns from each group were luted with resin-modified glass ionomer (RMGI, RelyX Luting Plus) and half were luted with a resin cement (RelyX Unicem 2) to resin composite dies. Crowns were load cycled (100,000 cycles, 100 N force, 24°C water) and then loaded with a steel indenter until failure. A three-way ANOVA examined the effects of material, cement, and surface treatment on fracture load. Post-hoc comparisons were performed with the Tukey-Krammer method. RESULTS: Fracture load was signficiantly different for materials and cements (p < 0.0001) but not surface treatments (p = 0.77). All lithium disilicate crowns luted with RMGI failed in fatigue loading cycling; 3Y-PSZ and 5Y-Z crowns luted with resin showed a higher fracture load compared with RMGI (p < 0.001). With resin cement, there was no signficant difference in fracture load between 5Y-Z and lithium disiliciate (p = 1) whereas 3Y-PSZ had a higher fracture load (p < 0.0001). CONCLUSIONS: Cement type affected fracture load of crowns but surface treatment did not. The 0.8 mm uniform thick crowns tested benefited from using resin cement regardless of type of ceramic material. Crowns fabricated from 5Y-Z may be particle-abraded if luted with resin cement.


Asunto(s)
Fracaso de la Restauración Dental , Estética Dental , Cerámica , Coronas , Porcelana Dental , Análisis del Estrés Dental , Ensayo de Materiales , Cementos de Resina , Circonio
13.
J Am Dent Assoc ; 150(6): 522-530, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-31030937

RESUMEN

BACKGROUND: In this article, the authors present clinical factors associated with the type of cement practitioners use for restoration of single-unit crowns. METHODS: A total of 202 dentists in The National Dental Practice-Based Research Network recorded clinical details (including cement type) used for 3,468 single-unit crowns. The authors classified crowns as bonded if the dentist used a resin cement. The authors used mixed-model logistic regression to assess the associations between various clinical factors and the dentist's decision to bond. RESULTS: A total of 38.1% of crowns were bonded, and 61.9% were nonbonded; 39.1% (79 of 202) of dentists never bonded a crown, and 20.3% (41 of 202) of dentists bonded every crown in the study. Crowns with excessive occlusal reduction (as judged by laboratory technicians) were more likely to be bonded (P = .02); however, there was no association with bonding and excessive taper (P = .15) or axial reduction (P = .08). Crowns were more likely to be bonded if they were fabricated from leucite-reinforced glass ceramic (76.5%) or lithium disilicate (70.8%) than if they were fabricated from layered zirconia (38.8%), full-contour zirconia (30.1%), full metal (14.7%), or porcelain-fused-to-metal (13.8%) (P < .01) restorative material. There was no significant association between choice to bond and crown margin location (P = .35). Crowns in the anterior maxilla were more likely to be bonded (P < .01). CONCLUSIONS: Excessive occlusal tooth preparation, anterior location of a crown, and the use of glass ceramic crowns were associated significantly with the decision to bond. PRACTICAL IMPLICATIONS: In this study, the authors identified factors significantly associated with the clinical decision made by practicing dentists when selecting a cement for restoration of single-unit crowns.


Asunto(s)
Coronas , Cementos Dentales , Materiales Dentales , Porcelana Dental , Diseño de Prótesis Dental , Análisis del Estrés Dental , Cementos de Ionómero Vitreo , Ensayo de Materiales , Cementos de Resina
15.
Am J Dent ; 31(2): 97-102, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29630794

RESUMEN

PURPOSE: To evaluate the effect of different surface treatments and primers with a CAD/CAM resin composite block on its crown retention. METHODS: 120 human molars were prepared with a 24° total convergence angle, 1.5 mm height, and axial walls in dentin. Surface area was measured by digital microscopy. Crowns were machined from CAD/CAM resin composite blocks. Teeth were randomly allocated to 12 groups (n= 10) based on possible combinations of three surface treatments: [Control, Alumina air abrasion (50-µm Al2O3 at 0.28 MPa) ]; 5% hydrofluoric acid etch (20-second scrub); silane application (with or without Kerr Silane primer); and adhesive application (with or without Optibond XTR Adhesive). Optibond XTR Adhesive was applied to the tooth preparations and crowns were bonded with MaxCem Elite cement. Crowns were fatigued for 100,000 cycles at 100 N in water and debonded in tension (1 mm/minute). Crown retention strength (maximum load/surface area) values were analyzed using a three-way ANOVA with Tukey's post-hoc tests (α= 0.05). RESULTS: Surface treatment, silane and adhesive applications independently affect retention force (P< 0.05). All interactions were not significant (P> 0.05). Alumina airborne abrasion surface treatment, silane and adhesive applications all improve retention strength. Therefore, CAD/CAM resin composite crowns can withstand debonding while undergoing mechanical fatigue. Although all forms of surface treatment and primer application improve bond strength, the highest mean retention strength values were recorded when the crowns were alumina particle abraded and coated with adhesive (with or without silane). CLINICAL SIGNIFICANCE: In order to improve the bonding of resin composite crowns, application of alumina airborne particle abrasion and a coat of adhesive (proceeded by an optional coat of silane) is recommended. If hydrofluoric acid is utilized, the crowns should be treated with a coat of silane followed by adhesive application.


Asunto(s)
Resinas Compuestas , Diseño Asistido por Computadora , Coronas , Recubrimiento Dental Adhesivo , Cementos Dentales , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Distribución Aleatoria , Cementos de Resina , Estrés Mecánico , Propiedades de Superficie
16.
J Dent Educ ; 82(3): 252-259, 2018 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29496803

RESUMEN

An Integrated National Board Dental Examination (INBDE) combining basic, behavioral, and clinical sciences will be implemented in 2020 to replace the current two-part National Board Dental Examination required for all candidates who seek to practice dentistry in the U.S. The aims of this study were to determine how U.S. dental schools are preparing for implementation of the INBDE and to assess their top administrators' attitudes about the new exam. A total of 150 deans, academic deans, and other administrators at all 64 U.S. dental schools with graduating classes in 2016 were emailed a 19-question electronic survey. The survey questions addressed the respondents' level of support, perceived benefits and challenges, and planned preparation strategies for the INBDE. The individual response rate was 59%, representing 57 of the 64 schools. Approximately 60% of the respondents either agreed or strongly agreed that they support the integrated exam, while roughly 25% either somewhat or strongly disagreed. While most respondents (72%) reported that their institutions would be prepared for the INBDE, 74% reported that the merged exam created additional strain for their institutions. Respondents reported viewing content integration and clinical applicability as benefits of the INBDE, while required curriculum changes and student preparedness and stress were seen as challenges. Most of the respondents reported their schools were currently employing strategies to prepare for the INBDE including meetings with faculty and students and changes to curricula and course content. The beginning of the fourth year and the end of the third year were the most frequently reported times when schools planned to require students to take the INBDE, although almost half of the respondents did not yet know what it would be required at their school. Several schools were reconsidering using the boards as a passing requirement. This study found that support for the INBDE was not universal, but strategies are under way to prepare students, faculty, and curricula for this new means of assessment.


Asunto(s)
Licencia en Odontología , Facultades de Odontología , Consejos de Especialidades , Actitud del Personal de Salud , Humanos , Licencia en Odontología/normas , Facultades de Odontología/organización & administración , Consejos de Especialidades/organización & administración , Consejos de Especialidades/normas , Encuestas y Cuestionarios , Estados Unidos
17.
J Prosthet Dent ; 120(1): 132-137, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29310875

RESUMEN

STATEMENT OF PROBLEM: Three mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) possesses excellent mechanical properties but is relatively opaque. Five mol% yttria-stabilized zirconia polycrystal (5Y-ZP) offers improved translucency, but many of its clinical properties have not been compared with those of 3Y-TZP and lithium disilicate. PURPOSE: The purpose of this in vitro study was to compare the flexural strength, translucency parameter, bond strength, and enamel and material wear of 5Y-ZP (Katana UTML) with 3Y-TZP (Katana HT) and lithium disilicate (e.max CAD). MATERIAL AND METHODS: Flexural strength bars were sectioned (n=10, 25×4×2 mm), sintered or crystallized, polished, and fractured at 1 mm/min. Translucency specimens (1 mm thick) were fabricated (n=10). Their L*a*b* values were measured against a black-and-white background with a spectrophotometer, and ΔE00 was calculated. Zirconia bond strength specimens were airborne-particle abraded with 50 µm alumina followed by the application of a 10-methacryloxydecyl dihydrogen phosphate-containing primer (Clearfil Ceramic Primer). Lithium disilicate bond strength specimens were etched with 5% hydrofluoric acid followed by application of a silane-containing primer (Clearfil Ceramic Primer). A Tygon tube filled with resin cement (Panavia SA) was fixed to the surface of the ceramics and light-polymerized. After 1 day or 150 days of water storage, the resin cement was debonded in a macroshear test (n=10). The cusps of extracted human molars were isolated and mounted into the University of Alabama at Birmingham wear-testing device. Wear testing was performed with a 20-N load for 300000 cycles in 33% glycerin. The volumetric wear of polished zirconia, lithium disilicate, and enamel were measured along with the wear of the opposing enamel cusps using a noncontact profilometer (n=8). The data were compared by ANOVA and Tukey-Kramer analysis (α=.05). RESULTS: No statistical difference was seen between the bond strengths (P=.155) or the opposing enamel wear (P=.533) of different ceramics. A statistically significant difference was seen between the flexural strength (P<.001), translucency parameter (P<.001), and wear (P<.001) of the materials. The flexural strength values (MPa) were 1194 ±111 (Katana HT), 688 ±159 (Katana UTML), and 450 ±53 (e.max LT). The translucency parameter values were 6.96 ±0.53 (Katana HT), 8.30 ±0.24 (Katana UTML), 9.28 ±0.36 (e.max LT), and 12.64 ±0.48 (e.max HT). Bond strength values (MPa) at 1 and 150 days were 34.22 ±5.14 and 28.37 ±6.03 (Katana HT), 35.04 ±5.69 and 25.03 ±6.44 (Katana UTML), and 35.50 ±3.45 and 22.32 ±3.45 (e.max LT). Material and enamel wear (mm3) were 0 and 0.24 ±0.19 (Katana HT), 0 and 0.23 ±0.09 (Katana UTML), 0.28 ±0.13 and 0.31 ±0.10 (e.max CAD), and 0.09 ±0.03 and 0.31 ±0.14 (enamel). CONCLUSIONS: 5Y-TZP has a flexural strength and translucency parameter between those of 3Y-TZP and lithium disilicate. Both the short-term and long-term bond strength of 5Y-ZP and 3Y-TZP was shown to be similar to lithium disilicate. 5Y-ZP demonstrated no measurable material wear and opposing enamel wear similar to that of all the other materials tested.


Asunto(s)
Materiales Dentales/química , Porcelana Dental/química , Circonio/química , Grabado Ácido Dental , Análisis del Estrés Dental , Resistencia Flexional , Técnicas In Vitro , Luz , Ensayo de Materiales , Metacrilatos , Compuestos de Organosilicio , Cementos de Resina , Propiedades de Superficie , Itrio/química
18.
Int J Oral Maxillofac Implants ; 33(3): 530­535, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29355855

RESUMEN

PURPOSE: Screw-retained zirconia implant crowns with an internal titanium base have favorable mechanical properties compared with single-piece zirconia implant crowns; however, the screw-retained implant crowns require adequate bonding between the zirconia crown and the titanium base. This study measured the retention between a titanium base and a full-contour zirconia implant crown following different surface treatments of their bonded surfaces. MATERIALS AND METHODS: Full-contour screw-retained zirconia implant crowns were fabricated to fit a titanium base. The crowns were bonded to the titanium bases following one of four treatment protocols (n = 15 per protocol group): no surface treatment (Control), 10-methacryloyloxydecyl dihydrogen phosphate (MDP) primer on the intaglio of crown and exterior of base (MDP), alumina airborne-particle abrasion of the intaglio of crown and exterior of base (Alu), and alumina airborne-particle abrasion and an MDP primer on the intaglio of crown and exterior of base (Alu+MDP). All crowns were bonded to the base with resin cement. Specimens were stored in water for 24 hours at 37°C and then thermocycled in water, with a temperature range of 5°C to 55°C, for 15,000 cycles with a 15-second dwell time. Crowns were separated from the titanium bases using a universal testing machine. The four treatment protocols were compared using one-way analysis of variance (ANOVA), followed by Tukey post hoc tests (P < .05). Sectioned specimens were examined with scanning electron microscopy (SEM). RESULTS: Retention forces for Control (737.8 ± 148.9 N) and MDP (804.1 ± 114.5 N) were significantly greater than Alu+MDP (595.5 ± 122.2 N), which was significantly greater than Alu (428.2 ± 93.8 N). Visual inspection of the debonded specimens showed that the majority of the cement remnants were seen on the external surface of the titanium bases. Microscopic examination of the interface between the crown and the unaltered base shows that the cement gap is approximately 13 µm at the crest of the microgrooves and 50 µm within the channel of the microgrooves. After airborne-particle abrasion, the microgrooves became significantly dulled, and the cement gap increased to 27 to 40 µm at the crest and 55 to 58 µm in the channels. CONCLUSION: Airborne-particle abrasion of titanium bases that contain retentive microgrooves prior to bonding is contraindicated. Application of an MDP primer demonstrated limited improvement in the retention of the zirconia implant crowns.


Asunto(s)
Coronas , Grabado Dental/métodos , Materiales Dentales/normas , Retención de Prótesis Dentales/normas , Análisis del Estrés Dental/métodos , Titanio , Circonio , Análisis de Varianza , Humanos , Ensayo de Materiales/métodos , Propiedades de Superficie
19.
J Esthet Restor Dent ; 30(1): 73-80, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29194924

RESUMEN

OBJECTIVES: To measure microleakage around zirconia crown margins cemented with self-adhesive resin or resin modified glass ionomer (RMGI) cement after ultrasonic scaling. METHODS: 16 molars were prepared for crowns (margin 0.5 mm coronal of cementum-enamel junction). Preparations were digitally scanned and zirconia crowns milled. Specimens were divided into two groups (n = 8): self-adhesive resin (RelyX Unicem 2) or resin modified glass ionomer (RMGI) (RelyX Luting Plus) cements. After cementation, specimens were ultrasonic scaled with a piezoelectric device (60 s, hand pressure). After thermocycling (20,000 cycles/5-55°C), specimens were immersed in 5 wt% fuchsine dye before sectioning bucco-lingually. Microleakage was examined under 40× light magnification. Statistical comparisons were made using a paired t test and a two-sample t test (α = .05). RESULTS: Ultrasonic scaling did not alter microleakage at the margins of crowns (P = .31). There was no significant difference in microleakage of scaled and untreated margins with the use of different cements (P = .21). The amount of microleakage around margins that were scaled was not significantly different between cements (P = .14). Untreated margins of crowns cemented with RelyX Luting Plus showed a significantly higher microleakage than those cemented with RelyX Unicem 2 (P = .005). CONCLUSIONS: Piezoelectric ultrasonic scaling did not increase microleakage at the margin of zirconia crowns cemented with self-adhesive resin or RMGI cements. CLINICAL SIGNIFICANCE: Piezoelectric ultrasonic scaling around zirconia crowns did not impact marginal microleakage cemented with self-adhesive resin or RMGI cements.


Asunto(s)
Filtración Dental , Cementos de Ionómero Vitreo , Cementación , Resinas Compuestas , Coronas , Cementos Dentales , Humanos , Ensayo de Materiales , Cementos de Resina , Ultrasonido , Circonio
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA