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1.
J Prosthet Dent ; 2021 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-33423821

RESUMEN

STATEMENT OF PROBLEM: The clinical success of monolithic lithium disilicate glass-ceramic (LDGC) crowns manufactured with computer-aided design and computer-aided manufacturing (CAD-CAM) technology provided by predoctoral students has not been fully investigated. PURPOSE: The purpose of this retrospective clinical study was to evaluate the performance of laboratory-fabricated monolithic posterior LDGC CAD-CAM crowns provided by predoctoral students at the University of Toronto. Specific patient- and provider-related factors were also investigated. MATERIAL AND METHODS: A sample of posterior LDGC CAD-CAM crowns (IPS e.max) provided by predoctoral students was evaluated. Crown preparations were made according to specific criteria, and crowns were milled in an in-house laboratory by using the CEREC Bluecam system. The crowns were cemented with Rely-X Unicem (3M ESPE) and Calibra Universal (Dentsply Sirona) resin cements. Clinical assessments of the crowns and supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Intraoral photographs and periapical and bitewing radiographs were obtained for further assessment by 2 evaluators. Descriptive statistics, McNemar, t test, log rank (Mantel-Cox) tests, Pearson chi-squared tests, simple logistic regression, odds ratios, and Kaplan Meier survival analyses were performed (α=.05). RESULTS: A total of 189 patients receiving 210 crowns (108 premolar and 102 molar) were examined with a follow-up period of up to 6 years. Altogether, 28 complications were observed (12 technical, 11 biological, and 5 esthetic). No significant association was found between patient age, sex, periodontal condition, tooth type, tooth vitality, cement type, and crown longevity. However, significantly lower survival and success rates were found for mandibular crowns than for maxillary crowns (P=.029). The provider's experience had no significant effect on the clinical performance of LDGC CAD-CAM crowns. The 6-year cumulative survival rate was 93.0%, and the success rate was 86.4%. CONCLUSIONS: The ease of use of the CAD-CAM system and clinical performance of LDGC suggest that this technology should be used in the dental school setting by predoctoral students.

2.
Dent Med Probl ; 57(2): 197-206, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32673449

RESUMEN

The use of ceramic materials and the computer-aided design/computer-aided manufacturing (CAD/CAM) technology for the fabrication of complete-coverage restorations has significantly increased in the last decade. The aim of this study was to evaluate the survival rate of anterior and posterior monolithic and bilayered lithium disilicate glass-ceramic (LDGC) CAD/CAM crowns, and to identify the types of complications associated with the main clinical outcomes reported in clinical trials. MEDLINE/PubMed, Embase, Scopus, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched by 2 independent reviewers for clinical studies published between 2006 and 2019, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The electronic search was supplemented by a hand search. Quality assessment for the included studies was performed. Qualitative and quantitative data was extracted from each study. Out of 219 studies, 6 studies that evaluated LDGC CAD/CAM crowns were identified and used for data extraction. The included studies had 154 participants, who received 204 crowns. The shortto medium-term survival and success rates were high. Biological complications occurred more frequently than technical complications. No esthetic complications were reported. This review indicated that the medium-term survival rate of LDGC CAD/CAM crowns was high. Further multicenter studies with longer follow-ups and larger sample sizes are needed in order to augment the data already in existence.


Asunto(s)
Diseño de Prótesis Dental , Estética Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Porcelana Dental , Humanos
3.
J Dent Educ ; 84(3): 329-335, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32176349

RESUMEN

The aims of this study were to determine the convergence angles of posterior teeth prepared by dental students at the University of Toronto for lithium disilicate glass-ceramic (LDGC) CAD/CAM crowns and to investigate their effect on loss of retention rate. A total of 280 preparations for posterior monolithic LDGC CAD/CAM crowns were performed on 270 patients (169 women and 101 men). Crowns were cemented with RelyX Unicem and Calibra Universal resin cements. Mesial, distal, and angle of convergence were measured on the bitewing radiographs. Cemented crowns were followed for up to six years. Data were analyzed for tooth type and location and for operator experience. The results showed the majority of convergence angles were greater than the recommended guidelines but fell within a clinically acceptable range (20 to 24 degrees). However, angles of convergence for mandibular molar preparations were highest (28.06±5.50 degrees), while maxillary premolars exhibited the lowest values (24.72±6.59 degrees). No significant difference was found between the results of dental students and foreign-trained dentists. Over a six-year observation period, only two crowns lost retention. The findings of this study indicated that ideal taper angles were impractical and difficult to achieve in clinical education settings.


Asunto(s)
Coronas , Estudiantes de Odontología , Cerámica , Diseño Asistido por Computadora , Porcelana Dental , Diseño de Prótesis Dental , Femenino , Humanos , Masculino , Ensayo de Materiales
4.
J Esthet Restor Dent ; 31(6): 613-619, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31565848

RESUMEN

OBJECTIVES: To evaluate the clinical performance and the effect of various patient and provider-related factors on the longevity of chairside monolithic posterior lithium disilicate glass-ceramic (LDGC) computer-aided design (CAD)-computer-aided manufacturing (CAM) crowns provided by predoctoral students. MATERIALS AND METHODS: A sample of posterior LDGC CAD-CAM crowns was evaluated. Crown preparations were milled chairside using the CEREC Omnicam system and cemented with Rely-X Unicem or Calibra Universal resin cements. Clinical assessment of the crowns and supporting periodontal structures was performed using the modified California Dental Association (CDA) criteria. Intraoral photographs as well as radiographs were taken for further assessment by two evaluators. Kaplan-Meier survival analysis was performed. RESULTS: A total of 40 crowns were inserted in 32 patients and evaluated for 4 years. Three complications were observed (two-technical and one-biological). No chipping or fracture of crowns was observed. No significant association was found between age, sex, periodontal condition, tooth type, tooth vitality, cement type, and longevity. The 4-year cumulative survival and success rates were 95.0 and 92.3%, respectively. CONCLUSION: Chairside LDGC CAD-CAM crowns exhibited a high survival rate after 4 years in function and were shown to be a viable and reliable treatment option for posterior teeth. CLINICAL SIGNIFICANCE: The high survival rate of chairside CAD-CAM crowns observed in this study suggests the likelihood of predictable performance in the predoctoral setup.


Asunto(s)
Porcelana Dental , Diseño de Prótesis Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Humanos , Ensayo de Materiales
6.
Dent Med Probl ; 55(2): 207-211, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30152626

RESUMEN

New glass-ceramic restorative materials have been developed over the last few years, with enhanced strength characteristics along with desirable optical properties that make them ideal for the fabrication of esthetic crowns and veneers. The purpose of this paper was to provide an overview of the current state of the art of porcelain veneers as a viable option for the esthetic treatment of anterior teeth, and to illustrate the potential of the newly-developed glass-ceramics. Some historical background about the development of the porcelain veneer concept is provided. A list of indications and contraindications for porcelain veneers is followed by their preparation designs, with emphasis on the importance of maintaining the preparation boundaries within the enamel. Impression-taking procedures, provisional restoration fabrication, the choice of porcelain materials and their intaglio surface treatment are all discussed. A case where veneers made with a lithium-disilicate glass-ceramic were used to improve the appearance of maxillary anterior teeth is included. Several studies reporting on the longevity of porcelain veneers up to 12 years are discussed.


Asunto(s)
Porcelana Dental , Coronas con Frente Estético , Grabado Ácido Dental , Cerámica , Técnica de Impresión Dental , Fracaso de la Restauración Dental , Humanos
7.
Dent Med Probl ; 55(1): 35-42, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30152633

RESUMEN

BACKGROUND: All-ceramic restorations have become popular and the trend is ongoing. However, the incidence of chipping within the veneering layer has been a commonly reported failure in clinical practice. OBJECTIVES: The aim of this in vitro study was to evaluate the effect of ceramic crown design (monolithic vs bi-layered) and material on the chipping resistance of molar crowns submitted to compressive cyclic loading. MATERIAL AND METHODS: Fifty identical epoxy resin replicas of a mandibular first molar with crown preparation were divided into 5 groups (n = 10) as follows: the MLD group - monolithic CAD/CAM lithium-disilicate glass-ceramic (LDGC) crowns; 30 zirconia cores were veneered with either feldspathic porcelain by hand-layering technique (ZHL) or by heat-pressing technique (ZVP), or with milled LDGC veneers and subsequently fused to the cores (ZLD); 10 porcelain-fused-to-metal (PFM) crowns acted as a control group. All crowns were cemented using Panavia® F2.0 resin cement (Kuraray Dental, Tokyo, Japan). After storage in water at 37°C for 1 week, the specimens were subjected to compressive cyclic loading at the mesiobuccal cusp which was tilted at 30°. A load cycle of 50-450 N was used and specimens were maintained in an aqueous environment throughout 500,000 cycles in a universal testing machine (Instron, Norwood, USA). The data was statistically analyzed at 5% significant level with Fisher's exact test and Kaplan-Meier survival analysis. RESULTS: Significant differences in survival rates of the specimens used in the groups (p < 0.001) were found. Specimens of the PFM, ZHL and ZVP groups underwent failures at different stages of the 500,000 fatigue cycles, while specimens of the MLD and ZLD groups survived the entire fatigue test. ZHL and ZVP crowns had the worst chipping-resistance, while PFM crowns performed slightly better. The Kaplan-Meier test revealed significantly higher survival rates for the MLD and ZLD specimens compared to the other 3 groups. CONCLUSIONS: The use of LDGC as a monolithic molar crown and as a veneer over a zirconia core resulted in superior resistance to cuspal chipping.


Asunto(s)
Coronas , Diseño de Prótesis Dental , Fracaso de la Restauración Dental , Coronas con Frente Estético , Ensayo de Materiales , Cerámica , Porcelana Dental , Humanos , Técnicas In Vitro , Propiedades de Superficie , Circonio
8.
Dent Med Probl ; 55(4): 383-388, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30648363

RESUMEN

BACKGROUND: Bulk-fill composites were developed to simplify composite placement and minimize polymerization shrinkage stresses, which can improve gingival marginal adaptation in deep class II cavities. OBJECTIVES: The objective of this study was to compare the gingival microleakage of class II cavities restored with bulk-fill composites to that of incrementally restored ones with a conventional composite at 2 storage periods. MATERIAL AND METHODS: Forty freshly extracted intact molars were employed. Two standardized class II slot cavities, 3-millimeter-wide buccolingually, with the gingival floor 0.5 mm below the cementoenamel junction (CEJ) and the axial wall depth of 1.3 mm were prepared in each tooth (80 cavity preparations). The prepared teeth were divided equally into 3 bulk-fill groups (Tetric EvoCeram® Bulk Fill, X-tra Fil® and QuiXX®) and 1 control group (TPH Spectra® HV). Each group was subdivided into 2 equal subgroups (n = 10) according to the storage period in distilled water (24 h and 6 months). The Adper® Single Bond Plus adhesive was used with all the restorative materials. The cavities in the experimental groups were restored with 4-millimeter bulk-fill composites in 1 increment, while the cavities in the control group were restored with 2 increments of the thickness of 2 mm. The polymerization light was applied from the occlusal surfaces. The teeth were then immersed in 2% procion red dye solution, sectioned and examined under a stereomicroscope to determine the extent of dye penetration. The data was statistically analyzed using the Kruskal-Wallis test and the Mann-Whitney U test. RESULTS: The Kruskal-Wallis test revealed no significant differences in the mean microleakage scores among all the groups after 24-hour and 6-month storage (p = 0.945 and p = 0.928, respectively). The Mann-Whitney U test revealed an increase in the mean microleakage scores in all the groups after 6-month storage; however, the scores were not significantly different from the means obtained after 24 h (p = 0.259 for Tetric EvoCeram Bulk Fill; p = 0.205 for X-tra Fil; p = 0.166 for QuiXX; p = 0.155 for TPH Spectra HV). CONCLUSIONS: Gingival microleakage of bulk-fill composites in class II cavities was not significantly different from that of incrementally restored ones with a conventional composite. The increase in the mean gingival microleakage of the specimens stored for 6 months was not statistically significantly different in comparison to the values obtained after the 24-hour storage period for each composite.


Asunto(s)
Resinas Compuestas , Filtración Dental/etiología , Encía/patología , Resinas Compuestas/efectos adversos , Resinas Compuestas/uso terapéutico , Caries Dental/terapia , Restauración Dental Permanente/efectos adversos , Restauración Dental Permanente/métodos , Humanos
9.
J Esthet Restor Dent ; 29(3): 215-221, 2017 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-28417581

RESUMEN

STATEMENT OF PROBLEM: Monitoring performance of glass-ceramic based indirect restorations using radiographic imaging might be difficult due to their low radiopacity. Therefore, materials used for their cementation must possess adequate radiopacity. PURPOSE: This study determined radiopacity of a group of resin-cements used for adhesive-cementation of glass-ceramic-based restorations using digital radiography. METHODS: Two specimens were prepared from a group of resin cements (VariolinkII-opaque, VariolinkII-opaque (base), VariolinkII-Transparent, VariolinkII-Transparent (base), Nexus, RelyX Unicem, RelyX ultimate, Duolink, Monocem and Resinomer) and longitudinal sections of same thickness were obtained from molar and premolar. Specimens were assigned to two groups one had molar section with 10 specimens whereas other had premolar with remaining 10 specimens. Each group was placed on digital radiograph sensor (Schick CDR, size 2) together with aluminum step-wedge. Sensor was exposed to X-ray using standard technique. Two images were obtained for each group. Pixel measurements were made using NIH Image-J software. Mean pixel measurements were converted into aluminum thickness equivalents. Data were statistically-analyzed using one-way ANOVA and Tukey's tests. RESULTS: ANOVA revealed significant difference in mean pixel values among cements (p < 0.001). VariolinkII-opaque showed highest mean aluminum equivalent (4.6 mm Al/1 mm) followed by VariolinkII-opaque-Base (4.5 mm Al/1 mm), VariolinkII-transparent (4.45 mm Al/1 mm), VariolinkII-transparent-Base (4.45 mm Al/1 mm), Nexus (2.95 mm Al/1 mm), Duolink (2.7 mm Al/1 mm), RelyX Unicem (2.2 mm Al/1 mm) and finally RelyX ultimate (2 mm Al/1 mm). All cements had mean radiopacity values higher than that of enamel whereas Monocem (1.25 mm Al/1 mm) and Resinomer (1.2 mm Al/1 mm) had means between those of enamel and dentin. CONCLUSIONS: All tested resin-cements showed radiopacity values higher than that of dentin which is adequate for diagnostic purposes according to ISO recommendation. CLINICAL SIGNIFICANCE: The use of resin cement with adequate radiopacity for adhesive cementation of glass-ceramic based restorations enables their radiographic monitoring. (J Esthet Restor Dent 29:215-221, 2017).


Asunto(s)
Materiales Dentales/química , Dentina/diagnóstico por imagen , Radiografía Dental Digital , Cementos de Resina/química , Cerámica/química , Resinas Compuestas , Curación por Luz de Adhesivos Dentales , Ensayo de Materiales , Polimerizacion
10.
Dent Mater J ; 35(6): 923-928, 2016 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-27773895

RESUMEN

During a fiber post cementation, bonding failure often occurs at the junction between the fiber-post and resin-cement. Because this failure requires better characterization, we evaluated if different post surface treatment can affect the bond strength of urethane dimethacrylate (UDMA) fiber-posts with resin-cements. Three groups were created: G1: no treatment/silane; G2: ethyl alcohol (96° GL)/silane; G3: 24% H2O2/silane and further divided into four subgroups: I-Unicem/3MESPE; II-BisCem/Bisco; III-Panavia SA/Kuraray and IV-DuoLink/Bisco. Blocks of cured resin cements and posts placed in the center were serially cut into bar-shaped specimens and loaded into a micro tensile testing machine. ANOVA indicated no significant differences among post surface treatments (p>0.05), however, significant within the resin cements (p<0.05) and the interaction of both (p<0.05). The G3/IV showed the highest bond strength values. SEM showed that surface treatments on UDMA fiber posts presented no benefits in terms of surface roughness, thus, should not be performed.


Asunto(s)
Recubrimiento Dental Adhesivo , Técnica de Perno Muñón , Cementos de Resina , Resinas Compuestas , Peróxido de Hidrógeno , Ensayo de Materiales , Propiedades de Superficie , Resistencia a la Tracción
11.
Dent Mater ; 32(7): 847-52, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-27133875

RESUMEN

OBJECTIVE: This in-vitro study determined plane-strain fracture toughness (KIC) of five different chairside CAD/CAM materials used for crown fabrication, following alternative innovative loading approach of compact tension test specimens. METHODS: Rectangular-shaped specimens were cut from CAD/CAM blocks (n=10): Vita Mark II (Vident) (VMII); Lava-Ultimate (3M/ESPE) (LU); Vita Enamic (Vident) (VE); IPS e.max CAD (Ivoclar Vivadent); crystallized and un-crystallized (E-max and E-max-U, respectively); and Celtra Duo (Dentsply) fired and unfired (CD and CD-U, respectively). Specimens were notched with thin diamond disk prior to testing. Instead of applying tensile loading through drilled holes, a specially-made wedge-shaped steel loading-bar was used to apply compressive load at the notch area in Instron universal testing machine. The bar engaged the top » of the notch before compressive load was applied at a cross-head speed of 0.5mm/min. Fracture load was recorded and KIC calculated. Data was statistically-analyzed with one-way ANOVA at 95% confidence level and Tukey's tests. RESULTS: Means and SDs of KIC in MPam(1/2) for VMII, LU, VE, E-max, E-max-U, CD and CD-U were: 0.73 (0.13), 0.85 (0.21), 1.02 (0.19), 1.88 (0.62), 0.81 (0.25), 2.65 (0.32) and 1.01 (0.15), respectively. ANOVA revealed significant difference among the groups (p<0.001). CD and E-max had significantly highest mean KIC values. SIGNIFICANCE: Mean KIC values of the tested materials varied considerably, however, none of them reached mean KIC of dentin (3.08MPam(1/2)) previously reported. For E-max and CD, specimens firing significantly increased mean KIC. The modified test arrangement was found to be easy to follow and simplified specimen preparation process.


Asunto(s)
Diseño Asistido por Computadora , Coronas , Humanos , Ensayo de Materiales
12.
Int J Prosthodont ; 29(3): 271-3, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27148988

RESUMEN

PURPOSE: This study determined the radiopacity of a group of computer-aided design/computer-assisted manufacture blocks using digital radiography and pixel monitoring. MATERIALS AND METHODS: Specimens 2.0 ± 0.05-mm thick were cut from nine different blocks. Longitudinal sections of the same thickness were obtained from molar and premolar. Specimens were assigned to one of two groups, and each group was placed on a digital radiograph sensor together with an aluminum step wedge. Following standardized technique, the sensor was exposed and two images were obtained from each group. Images were analyzed using ImageJ software to determine the number of pixels at five different locations for each specimen. Means and standard deviations were calculated and the data statistically analyzed. Radiopacity values were expressed as equivalent of aluminum thickness. RESULTS: Analysis of variance revealed significant difference in mean pixels among the blocks (P < .001). CONCLUSION: The majority of blocks had radiopacity values that were higher than that of dentin.


Asunto(s)
Diseño Asistido por Computadora , Medios de Contraste/química , Porcelana Dental/química , Radiografía Dental Digital/métodos , Aluminio/química , Silicatos de Aluminio/química , Cerámica/química , Resinas Compuestas/química , Esmalte Dental/diagnóstico por imagen , Dentina/diagnóstico por imagen , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Compuestos de Potasio/química , Circonio/química
13.
J Esthet Restor Dent ; 28(2): 122-30, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26892364

RESUMEN

OBJECTIVE: This in vitro study compared cuspal deflection of premolars restored with three bulk-fill composite resins to that of incrementally-restored ones with a low-shrinkage silorane-based restorative material. MATERIALS AND METHODS: Forty freshly-extracted intact human upper premolars were used. Reference points at buccal and palatal cusp tips were acid-etched and composite rods were horizontally bonded to them (TPH-Spectra-HV, Dentsply). Two acrylic resin guiding paths were made for each premolar to guide beaks of a digital micrometer used for cuspal deflection measurements. Standardized MOD cavities, 3 mm wide bucco-lingually and 3.5 mm deep, were prepared on each premolar. Prepared teeth were then equally divided into four groups (n = 10) and each group was assigned to one of four composite resin (QuiXX, Dentsply; X-tra fil, Voco; Tetric EvoCeram Bulk Fill, Ivoclar Vivadent; low-shrinkage Filtek LS, 3M/ESPE). Adper Single Bond-Plus, 3M/ESPE was used with all bulk-fill restoratives. LS-System Adhesive, 3M/ESPE was used with Filtek LS. For each prepared premolar, cuspal deflection was measured in microns as the difference between two readings between reference points before and after restoration completion. Means and SDs were calculated and data statistically-analyzed using One-way ANOVA and Tukey's test. RESULTS: Filtek LS showed the lowest mean cuspal deflection value 6.4(0.84)µm followed by Tetric EvoCeram Bulk Fill 10.1(1.2) µm and X-tra fil 12.4(1.35)µm, while QuiXX showed the highest mean 13(1.05)µm. ANOVA indicated significant difference among mean values of groups (p < 0.001). Tukey's test indicated no significant difference in mean values between QuiXX and X-tra fil (p = 0.637). CONCLUSIONS: Tetric EvoCeram Bulk Fill had significantly lower mean cuspal deflection compared with the two other bulk-fill composite resins tested. Filtek LS had the lowest significant mean cuspal deflection in comparison to all tested bulk-fill restoratives. CLINICAL SIGNIFICANCE: The use of Tetric EvoCeram Bulk fill composite resin restorative for class II MOD cavities resulted in reduced cuspal deflection in comparison to the two other bulk-fill composite resins tested. The silorane-based Filtek LS restorative resulted in the least cuspal deflection in comparison to all tested bulk-fill composite restoratives.


Asunto(s)
Diente Premolar/química , Resinas Compuestas , Humanos
15.
J Contemp Dent Pract ; 16(2): 147-53, 2015 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-25906807

RESUMEN

PURPOSE: The purpose of this study was to evaluate the effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root regions. MATERIALS AND METHODS: Sixty single-rooted human teeth were decoronated, endodontically treated, post-space prepared, and divided into six groups. Glass-fiber (GF) posts (Exacto, Angelus) and fiber-reinforced composite (FRC) posts (EverStick, StickTeck) were cemented with self-adhesive resin cement (Breeze) (SA) (Pentral Clinical) and self-etching resin cement (Panavia-F) (SE) (Kuraray). Six 1-mm-thick rods were obtained from the cervical (C), middle (M), and apical (A) regions of the roots. The specimens were then subjected to microtensile testing in a special machine (BISCO; Schaumburg, IL, USA) at a crosshead speed of 0.5 mm/min. Microtensile bond strength data were analyzed with two-way ANOVA and Tukey's tests. RESULTS: Means (and SD) of the MPa were: GF/SA/C: 14.32 (2.84), GF/SA/M: 10.69 (2.72), GF/SA/A: 6.77 (2.17), GF/SE/C: 11.56 (4.13), GF/SE/M: 6.49 (2.54), GF/SE/A: 3.60 (1.29), FRC/SA/C: 16.89 (2.66), FRC/SA/M: 13.18 (2.19), FRC/SA/A: 8.45 (1.77), FRC/SE/C: 13.69 (3.26), FRC/SE/M: 9.58 (2.23), FRC/SE/A: 5.62 (2.12). The difference among the regions was statistically significant for all groups (p < 0.05). The self-adhesive resin cement showed better results than the self-etching resin cement when compared to each post (p < 0.05). No statistically significant differences in bond strengths of the resin cements when comparable to each post (p > 0.05). CONCLUSION: The bond strength values were significantly affected by the resin cement and the highest values were found for self-adhesive resin cement.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Cavidad Pulpar/ultraestructura , Técnica de Perno Muñón/instrumentación , Cementos de Resina/química , Cementación/métodos , Resinas Compuestas/química , Materiales Dentales/química , Análisis del Estrés Dental/instrumentación , Vidrio/química , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Distribución Aleatoria , Preparación del Conducto Radicular/métodos , Estrés Mecánico , Propiedades de Superficie , Resistencia a la Tracción , Ápice del Diente/ultraestructura , Cuello del Diente/ultraestructura , Diente no Vital/patología
16.
J Contemp Dent Pract ; 14(4): 622-8, 2013 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-24309339

RESUMEN

AIM: This study investigated the effect of different fiber inserts (glass and polyethylene), bonding agents, and resin composites on the gingival margin microleakage of class V composite restorations. MATERIALS AND METHODS: Sixty premolars were sterilized and mounted in acrylic resin bases. Class V cavities were prepared buccally and lingually, 1 mm below the cementoenamel junction, comprising 12 groups (n = 10). In the experimental groups fiber inserts were cut and placed at the gingival seat, while the control groups had no inserts. Combinations of two composite materials, Filtek-Z250 and Filtek-LS (3M-ESPE), and four bonding agents, Clearfil SE bond (Kuraray) (C), Scotch Bond Multipurpose (3M-ESPE) (SB), Prime and Bond NT (Dentsply) (PB), and Filtek-LS (3M-ESPE) (LS) were used. Restorations were incrementally inserted and polymerized for 40s. Specimens were then stored in distilled water for 7 days and thermocycled for 500 cycles. Teeth surfaces were sealed with nail polish except for 1 mm around restoration margins and immersed in 2% red procion dye. Teeth were then sectioned buccolingually and dye penetration was assessed with five-point scale. Data were statistically-analyzed by Kruskal-Wallis, ANOVA and Tukey's tests (α = 5%). RESULTS: Mean microleakage scores varied from 0.40 (Groups C, C with polyethylene, LS, LS with polyethylene) to 1.50 (SB). CONCLUSION: Different bonding agents led to differences in microleakage scores where C and LS showed significantly lower microleakage than PB. SB had highest mean microleakage score, however, incorporation of fibers resulted in significant reduction in microleakage. CLINICAL SIGNIFICANCE: Class V resin composite restorations bonded with a total-etch adhesive had a significant reduction in mean microleakage scores when glass or polyethylene fibers were placed at the gingival cavo-surface margin. In contrast, for two self-etch adhesive systems, the incorporation of fibers had no significant effect on mean microleakage scores.


Asunto(s)
Resinas Compuestas/química , Filtración Dental/clasificación , Materiales Dentales/química , Restauración Dental Permanente/clasificación , Vidrio/química , Polietileno/química , Cementos de Resina/química , Colorantes , Recubrimiento Dental Adhesivo/métodos , Preparación de la Cavidad Dental/clasificación , Humanos , Microscopía Electrónica de Rastreo , Polietilenos/química , Polimerizacion , Ácidos Polimetacrílicos/química , Propiedades de Superficie , Temperatura , Factores de Tiempo , Cuello del Diente/patología , Triazinas , Agua/química
17.
J Dent Educ ; 77(9): 1118-21, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24002848

RESUMEN

The aim of this study was to determine angle of convergence (AC) of posterior crown preparations made by predoctoral dental students at the University of Toronto. Ninety-one dies of students' crown preparations were digitally scanned with an in-Eos-Blue scanner (Sirona). Created images were virtually sliced at three similar locations of mesiodistal and buccolingual planes. Virtual protractor was used to determine AC of each section. Means and SDs were calculated, and data were statistically analyzed with ANOVA and student's t-test for operator's gender, experience, and tooth type. There were no significant differences among the groups except for AC of preparations grouped by tooth type (p<0.0001). The greatest mean mesiodistal AC was 26.4° found with mandibular molars, while the smallest was 16° found with maxillary premolars. ANOVA revealed significant difference in mean mesiodistal AC among groups (p<0.01). Also, greatest mean buccolingual AC was 25° found with mandibular molars, while the smallest was 20.8° found with maxillary premolars. ANOVA did not reveal significant difference in mean buccolingual AC among groups (p>0.05). Overall mean AC values were greater than ideal range of 2-5°; however, they were within ranges published for dentists/prosthodontists. Gender and experience had no significant effect on AC, but tooth type significantly affected AC.


Asunto(s)
Coronas , Diseño de Prótesis Dental , Prostodoncia/educación , Estudiantes de Odontología , Preparación Protodóncica del Diente , Análisis de Varianza , Pilares Dentales , Retención de Prótesis Dentales , Femenino , Humanos , Masculino , Ontario , Factores Sexuales , Estadísticas no Paramétricas
18.
Gen Dent ; 61(1): 36-40; quiz 41, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23302361

RESUMEN

This article describes CAD/CAM technology used in dentistry and different restorative materials used in conjunction with adhesive cementation with particular attention given to the evolution of the CEREC system, as well as various ceramics developed for this system. Advantages and limitations of materials and technique are also discussed.


Asunto(s)
Diseño Asistido por Computadora/instrumentación , Porcelana Dental/química , Diseño de Prótesis Dental , Restauración Dental Permanente/métodos , Estética Dental
19.
J Prosthodont ; 21(1): 28-32, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22008462

RESUMEN

PURPOSE: The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns. MATERIALS AND METHODS: Thirty-two extracted molars were prepared to receive CEREC crowns according to manufacturer's guidelines using a special paralleling device (Parallel-A-Prep). Sixteen feldspathic ceramic crowns (VITABLOCS Mark II) (VMII) and 16 resin-composite crowns (Paradigm-MZ100 blocks) (PMZ) were milled using a CEREC-3D machine. Eight crowns of each group were cemented to their respective teeth using self-etching resin cement (Panavia-F-2.0) (PAN), and eight were cemented using self-adhesive resin cement (RelyX-Unicem-Clicker) (RXU). Following storage for 1 week in water, specimens were subjected to uniaxial compressive cyclic loading in an Instron testing machine at 12 Hz for 1,000,000 cycles. Load was applied at the central fossa, and the cycle range was 60-600 N. Specimens were then subjected to microleakage testing. Data were statistically analyzed using factorial ANOVA and Post Hoc (Tukey HSD) tests. RESULTS: All composite crowns survived compressive cyclic loading without fracture, while three ceramic crowns from the subgroup cemented with RXU developed surface cracks at the center of occlusal surfaces, extending laterally. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other three subgroups (p < 0.05). CONCLUSIONS: After 1,000,000 cycles of compressive cyclic loading, PMZ composite molar crowns were more fatigue-resistant than VMII ceramic crowns. Cement type had a significant effect on fatigue resistance of the ceramic crowns but not the composite ones. Microleakage scores of ceramic crowns cemented with PAN were significantly lower than those of the other subgroups (p < 0.05).


Asunto(s)
Resinas Compuestas , Coronas , Recubrimiento Dental Adhesivo/métodos , Filtración Dental , Porcelana Dental , Análisis del Estrés Dental , Cementos de Resina , Análisis de Varianza , Fuerza Compresiva , Diseño Asistido por Computadora , Diseño de Prótesis Dental , Fracaso de la Restauración Dental , Recubrimientos Dentinarios , Humanos , Diente Molar , Estadísticas no Paramétricas , Circonio
20.
Int J Dent ; 2011: 536212, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-22114596

RESUMEN

To investigate the effect of prepolymerization warming on composites' mechanical properties, three composites were evaluated: Clearfil Majesty (CM) (Kuraray), Z-100 (3M/ESPE), and Light-Core (LC) (Bisco). Specimens were prepared from each composite at room temperature as control and 2 higher temperatures (37°C and 54°C) to test surface hardness (SH), compressive strength (CS), and diametral tensile strength (DTS). Data were statistically analyzed using ANOVA and Fisher's LSD tests. Results revealed that prewarming CM and Z100 specimens significantly improved their SH mean values (P < 0.05). Prewarming also improved mean CS values of Z100 specimens (P < 0.05). Furthermore, DTS mean value of CM prepared at 52° was significantly higher than that of room temperature specimens (P < 0.05). KHN, CS, and DTS mean values varied significantly among the three composites. In conclusion, Prewarming significantly enhanced surface hardness of 2 composites. Prewarming also improved bulk properties of the composites; however, this improvement was significant in only some of the tested materials.

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