Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 71
Filtrar
Más filtros










Intervalo de año de publicación
1.
J Prosthodont ; 2020 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-33038279

RESUMEN

PURPOSE: To evaluate and to compare the marginal and the internal fit of milled (MLE) and heat-pressed lithium disilicate endocrowns (PLE). MATERIALS AND METHODS: Thirty mandibular molars were prepared following the circumferential butt margin endocrown preparations; the cervical margin is parallel to the occlusal surface without ferrule design. A digital scan of molars was made using an intraoral digital scanner. The samples were separated into two groups (n = 15 per group); MLE: endocrowns were milled using LDS blocks and a 5-axis milling machine, PLE: endocrowns were heat-pressed using lost wax technique and LDS ingots. Marginal and internal adaptation were assessed using a replica technique and a stereomicroscope, selecting 32 measurements on each endocrown. Data were analyzed with one-way repeated measures ANOVA, two-way repeated measures ANOVA, student's t-test and paired student t-test (α = 0.05). RESULTS: Statistically significant interaction were recorded between fabrication technique and region (p < 0.05), F (1.97, 27.69) = 5.462. Group MLE displayed significantly smaller gaps than PLE in all regions (p < 0.001). The largest gap was observed at the pulpal floor in both groups. The internal gap was significantly larger than the marginal gap in MLE group (p < 0.001), while no statistically significant difference was observed in PLE group (p = 0.082). CONCLUSION: Heat-pressed and milled lithium disilicate endocrowns are clinically suitable, but the milled technique displayed a better fit than heat-pressed technique when marginal and internal adaptation were examined. This article is protected by copyright. All rights reserved.

2.
Biomater Investig Dent ; 7(1): 110-119, 2020 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-32939455

RESUMEN

Purpose: The purpose of this study was to assess fracture resistance, failure mode and stress concentration of a modified endocrown preparation design, under axial and lateral forces. Materials and Methods: Forty lower molars were divided into two groups (n = 20) and were restored with lithium disilicate glass-ceramic endocrowns following 2 preparation designs: Conventional, with circumferential butt margin 2 mm above the cemento-enamel junction; and Modified, by adding 2 grooves on the mesial side of the vestibular dentinal wall and on the distal side of the lingual dentinal wall. After cementation and thermomechanical cycling loading, half of the samples (n = 10) from each group were loaded axially and the other half (n = 10) was loaded laterally. Fracture resistance and failure modes were observed and the finite element analysis (FEA) was used to identify the stress concentration. Two-way ANOVA and Chi-square tests (α = 0.05) were used for in vitro data analyzes. Results: Fracture resistance showed a statistically significant difference between conventional and modified preparations (p < .001), and between axial and lateral loadings (p < .001). Conventional preparation recorded 2914 N under axial loading and 1516 N under lateral loading, while modified preparation recorded 3329 N under axial loading and 1871 N under lateral loading. FEA showed that retention grooves have reduced the stress concentration under both loads for the tooth and the restoration. Conclusion: Modified endocrown design showed higher fracture resistance than conventional endocrown. Lateral loading displayed a high percentage of severe fracture but under higher load to failure than the values reported for normal masticatory forces.

3.
J Int Soc Prev Community Dent ; 10(3): 292-299, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32802775

RESUMEN

Aim: The aim of this study was to evaluate the inclination of the maxillary incisors (I), facial axis (FA), and growth axis (GA) in different vertical and sagittal patterns. Materials and Methods: A total of 498 consecutive orthodontic patients, with an average age of 18.87 years (range = 5-63 years), were grouped based on their vertical and sagittal patterns. Maxillary incisors, FA, and GA axes were traced and their corresponding angles to nasion-basion and true horizontal lines were measured. The sample was divided into three groups based on the mandibular divergence (mandibular plane-MP/sella-nasion [SN]): Group 1-hypodivergent pattern (MP/SN ≤ 27; n = 30), Group 2-normodivergent pattern (27 < MP/SN <37; n = 254), and Group 3-hyperdivergent pattern (MP/SN ≥ 37; n = 214); the sample was then divided into three groups based on the sagittal pattern (ANB, angle between points A, Nasion and B): Group I-skeletal CLI (Class I) (0

4.
J Mech Behav Biomed Mater ; 110: 103892, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32778529

RESUMEN

AIM: Bioceramic-containing root canal sealers are the most recently introduced sealers in endodontics. The present work reported experiments on a bioceramic-based root canal sealer with the objective of improving its physiochemical properties via reinforcement with each one of the three different nanomaterials: multi-walled carbon nanotubes (MWCNTS), titanium carbide (TC) or boron nitride (BN) in two weight percentages (1 wt% and 2 wt%). METHODOLOGY: Each nanomaterial was added to a definite weight of BioRoot root canal sealer (BioRoot™ RCS, Septodont, Saint-Maur-des-Fossés, France). Three composite groups of each weight percentage were prepared for evaluation: BioRoot/MWCNTS, BioRoot/TC and BioRoot/BN. The initial and final setting times, solubility, elution and pH values of the freshly-mixed and set samples were evaluated and compared to pristine BioRoot™ RCS. Setting times were evaluated using Gilmore needles. Solubility and elution were determined after immersion in water for 24 h. Scanning electron microscopy was used to examine the microstructure of the composite materials. RESULTS: The 1-wt. % composites possessed significantly shorter initial and final setting times compared with the pristine BioRoot™ RCS (p < 0.05). The 2-wt.% composites exhibited longer initial setting times but significantly shorter final setting times than BioRoot RCS (p < 0.05). Most of the composites had relatively lower solubility and elution profiles, with BioRoot/1-wt.% TC and BioRoot/1-wt.% BN being the lowest (p < 0.05). BioRoot™ RCS and all composites exhibited an alkaline pH profile over a period of 4 weeks and a significantly higher alkaline pH (p < 0.05) was recorded for BioRoot/1-wt.% and Bioroot/2-wt.% TC. CONCLUSIONS: A bioceramic-containing root canal sealer (BioRootTM RCS) with a shorter setting time, an alkaline pH profile, and a relatively lower solubility may be developed by incorporation of nanomaterials.

5.
Int J Comput Dent ; 23(3): 225-233, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32789310

RESUMEN

AIM: To evaluate the fracture resistance and failure pattern of 3D-printed and milled composite resin crowns as a function of different material thicknesses. MATERIALS AND METHODS: Three typodont tooth models were prepared to receive a full coverage composite resin crown with different thicknesses (0.5, 1.0, and 1.5 mm). The prepared master casts were digitally scanned using an intraoral scanner, and the STL files were used to fabricate 60 nanocomposite crowns divided into two groups according to the material thickness (n = 10) and fabrication method: a 3D-printed group (3D) using an SLA printer with nanocomposite, and a milled group (M) using a milling machine and composite blocks. All crowns were adhesively seated on stereolithography (SLA)-fabricated dies. All samples were subjected to thermomechanical loading and fracture testing. The load to fracture [N] was recorded and the failure pattern evaluated. Data were statistically analyzed using a two-way ANOVA followed by a Bonferroni post hoc test. The level of significance was set at α = 0.05. RESULTS: The 3D group showed the highest values for fracture resistance compared with the milled group within the three tested thicknesses (P < 0.001). The 3D and M groups presented significantly higher load to fracture for the 1.5-mm thickness (2383.5 ± 188.58 N and 1284.7 ± 77.62 N, respectively) compared with the 1.0-mm thickness (1945.9 ± 65.32 N and 932.1 ± 41.29 N, respectively) and the 0.5-mm thickness, which showed the lowest values in both groups (1345.0 ± 101.15 N and 519.3 ± 32.96 N, respectively). A higher incidence of irreparable fractures was observed for the 1.5-mm thickness. CONCLUSION: 3D-printed composite resin crowns showed high fracture resistance at different material thicknesses and can be suggested as a viable solution in conservative dentistry.


Asunto(s)
Porcelana Dental , Fracaso de la Restauración Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Impresión Tridimensional
6.
J Contemp Dent Pract ; 21(4): 367-371, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32584270

RESUMEN

AIM: The aim of this study was to compare the adaptation of complete denture base (CDB) manufactured by three different techniques: conventional, milling, and three-dimensional (3-D) printing. MATERIALS AND METHODS: A master cast was duplicated to create 60 gypsum casts. Twenty casts (n = 20) were attributed to each group. In the computer-aided design and computer-aided manufacturing (CAD/CAM) groups (milling and 3-D printing), the 40 gypsum casts reserved for these two groups were scanned. An STL file was obtained and a master CDB was designed and then fabricated according to each technique. In the conventional group, a polyvinyl siloxane putty mold was obtained from the milled CDB, and this mold was used to fabricate 20 conventional denture bases by compression molding using the silicon-gypsum technique in a bronze flask. The inner surfaces of the obtained 60 CDB were scanned and superimposed over their corresponding master cast. Deviation analyses were calculated using digital subtraction technique. Five functional areas (posterior palatal seal, anterior border seal, crest of the ridge, maxillary tuberosities, and palate) were selected to evaluate the variations in CBD adaptation. RESULTS: Based on the results and color maps of all selected regions, milling technique offers the best adaptation. The crest of ridge in the conventional technique showed the least adaptation and the posterior palatal seal in the 3-D printing technique showed the best adaptation. CONCLUSION: Within the limitations of this study, the CAD/CAM fabrication techniques seem to offer better adaptation of CDB compared to the conventional fabrication technique. Milled CDBs presented the most homogeneous distribution of adaptation, yet the 3-D printing process seems a promising techniques that needs to be addressed and perfected. CLINICAL SIGNIFICANCE: The CAD/CAM technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.


Asunto(s)
Bases para Dentadura , Diseño de Dentadura , Diseño Asistido por Computadora , Dentadura Completa , Humanos , Impresión Tridimensional , Calidad de Vida
7.
Artículo en Inglés | MEDLINE | ID: mdl-32021475

RESUMEN

Purpose: The purpose of this study was to evaluate the effect of surface treatments on zirconia-resin bonding and the effect of aging on bond durability for one year. Method: Three hundred and twenty zirconia blocks were divided into 4 equal study groups. Group 1 (control): as-sintered, group 2: (GB): grit-blasted, group 3: (LAS): laser-etched, group 4: (SIE): selective infiltration etching. Composite cylinders were bonded to the zirconia with resin cement and ceramic primer. Aging was performed following 3 different aging protocols: thermocycling, storage in distilled water, or storage in an enzymatic esterase solution. Micro-shear bond strength test (µSBS) was recorded using a universal testing machine. µSBS values were analyzed using two-way Analysis of Variance followed by Tukey post-hoc tests. Level of significance was set at 0.05. Results: GB, LAS and SIE groups showed significantly higher values when compared to control. Groups GB, LAS and SIE reported a significant decrease up to 50% in µSBS after water storage and enzymatic degradation, while control group reported a 90% decrease. Failure analysis showed mainly adhesive failure for control group, while the percentage of cohesive failure in resin cement was higher in SIE group compared to GB and LAS groups. Conclusion: Water aging and esterase solutions played a significant role by increasing bond degradation. A minimum of one-year water and esterase storage medium should be used to evaluate the durability of the bond between resin cement and zirconia.

8.
J Prosthet Dent ; 123(1): 128-134, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31027958

RESUMEN

STATEMENT OF PROBLEM: Recent resin-based and ceramic-based computer-aided design and computer-aided manufacturing (CAD-CAM) materials have been used to restore endodontically treated teeth. Adaptation of the restoration is important for clinical success, but studies evaluating the effect of these materials on the adaptation of endocrowns are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of resin-based and ceramic-based materials on the marginal and internal adaptation of endocrowns. MATERIAL AND METHODS: Forty mandibular molars were divided into 4 groups (n=10); each group was restored with a different CAD-CAM material: group C: hybrid nanoceramic (Cerasmart; GC Corp), group T: fiber-composite material (Trilor; Bioloren Srl), group E: lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar Vivadent AG), and group V: zirconia-reinforced lithium silicate glass-ceramic (Vita Suprinity; VITA Zahnfabrik GmbH). A digital scan was made with an intraoral digital scanner (TRIOS 3; 3Shape A/S), and endocrowns were milled with a 5-axis milling machine (Coritec 250i; imes-icore GmbH). The replica technique and a stereomicroscope (×70) were used to measure the marginal and internal adaptation of the endocrowns at 32 points. All data were statistically analyzed using 1-way ANOVA and the Tukey honestly significant difference test (α=.05). RESULTS: Statistical tests showed significant differences among the tested groups (P<.001). The resin-based groups displayed larger discrepancies than the ceramic-based groups. The resin-based groups showed a mean marginal gap larger than the mean internal gap C (P=.009), T (P<.001), whereas the ceramic-based groups showed similar gaps, V (P=.396), E (P=.936). The largest gap was observed at the pulpal floor (P<.001). CONCLUSIONS: All materials had clinically acceptable internal and marginal gaps (≤150 µm), except for the marginal gap of the Trilor group.


Asunto(s)
Coronas , Diente no Vital , Cerámica , Diseño Asistido por Computadora , Adaptación Marginal Dental , Porcelana Dental , Diseño de Prótesis Dental , Humanos , Ensayo de Materiales
9.
J Contemp Dent Pract ; 20(9): 1003-1008, 2019 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-31797819

RESUMEN

AIM: The study aimed to assess the effect of friction and adhesion on the pushout bond strength of CAD/CAM fiber-reinforced composite (FRC) post and cores in comparison to prefabricated fiber posts. MATERIALS AND METHODS: Thirty extracted single-rooted premolars were divided into three groups (N = 10): CP: CAD/CAM FRC posts (Trilor, Bioloren) cemented with self-adhesive resin cement (Rely X U200, 3M) as control group. CPL: CAD/CAM FRC composite posts cemented with the same self-adhesive resin cement after lubricating the root canal with petroleum jelly (Vaseline, Unilever) to prevent adhesion. RXP: prefabricated posts cemented with self-adhesive resin cement. Specimens were subjected to thermal cycling and then to pushout tests. The mode of failure was observed using a stereomicroscope. Results were analyzed by two-way ANOVA followed by a Tukey's post hoc test for comparison, p = 0.05. RESULTS: Push-out bond strength was significantly lower in the RXP group (8.54 ± 3.35 MPa) in comparison to CP (12.10 ± 1.38 MPa), while no significant differences were concluded between the other groups. Failure was mostly adhesive for CPL and RXP and adhesive and mixed for CP. CONCLUSION: Custom made CAD/CAM posts have a positive effect on the retention of FRC posts to root canal walls while adhesion between self-adhesive cement and root dentin did not influence significantly the pushout bond strength of CAD/CAM posts to root canal. CLINICAL SIGNIFICANCE: The friction of well-adapted CAD/CAM fiber post and cores plays a predominant role in the success of post restorations of endodontically treated teeth.


Asunto(s)
Recubrimiento Dental Adhesivo , Técnica de Perno Muñón , Resinas Compuestas , Diseño Asistido por Computadora , Cavidad Pulpar , Análisis del Estrés Dental , Vidrio , Ensayo de Materiales , Cementos de Resina
10.
J Prosthodont ; 28(8): 898-905, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31397947

RESUMEN

PURPOSE: This study is to investigate the effect of milling custom fit anatomical post and cores from fiber reinforced composite and high-density polymer blocks using CAD/CAM technology on the bond strength to root canal dentin compared with prefabricated fiber posts, and to evaluate the influence of thermal cycling on the push out bond strength of the tested materials. MATERIALS AND METHODS: Eighty extracted single-rooted premolars, endodontically treated and prepared to receive the posts, were randomly divided into four groups (n = 20): BLC: Custom-milled fiber-reinforced composite posts and cores (Trilor, Bioloren), AMC: Custom-milled high-density polymer posts and cores (Ambarino, Creamed), BLP: Prefabricated fiber-reinforced composite posts and composite core buildups (Bioloren; Filtek Bulk Fill Posterior, 3M). The posts used have the same matrix and fiber composition as BLC, RXP: Prefabricated posts and composite core buildups (RelyX fiber post, 3M; Filtek Bulk Fill Posterior); used as a control group. All of the posts were cemented using a self-adhesive resin cement (RelyX U200, 3M). Half of the sample was randomly assigned to thermal cycling in distilled water for 6,000 cycles to simulate aging, while the other half was tested for bond strength without thermal cycling. A push-out test was conducted using a universal testing machine until failure. Bond strength values were calculated in megapascals (MPa). The mode of failure was observed using a stereo microscope. Results were analyzed by two-way ANOVA followed by a Bonferroni post hoc test for comparison. The level of significance was set at p < 0.05. RESULTS: Push-out bond strength was significantly higher (p <0.001) in the CAD/CAM post groups than in the groups with prefabricated posts regardless of the post material, while aging of the teeth did not significantly affect the push-out strength (p = 0.536). Failures were adhesive between cement and dentin for all groups except for AMC, where adhesive failure between the cement and the post was also observed. CONCLUSION: The CAD/CAM manufacturing technique was proved to ameliorate the retention of the post and cores in the root canal. Thermal cycling did not affect the bond strength of the tested groups.


Asunto(s)
Recubrimiento Dental Adhesivo , Técnica de Perno Muñón , Resinas Compuestas , Diseño Asistido por Computadora , Análisis del Estrés Dental , Dentina , Vidrio , Ensayo de Materiales , Cementos de Resina
11.
J Contemp Dent Pract ; 20(5): 571-576, 2019 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-31316020

RESUMEN

AIM: The internal fit and resistance to fracture of resin ceramics are to be evaluated compared to that of lithium disilicate as the control group. MATERIALS AND METHODS: Four groups of 20 crowns each (GC Cerasmart, Vita Enamic, Coltène Brilliant Crios, and e.max CAD) were cemented on identical metal dies. Marginal gaps were measured before cementation and load to fracture was applied after cementation, half of each group was thermodynamically aged (3,000 cycles of 5° to 55° immersion followed by 200,000 cycles of 100 N load), finally the crowns were loaded until fracture in a universal testing machine. Statistical package for social sciences (SPSS) package 23 was used for statistical work. RESULTS: Marginal gaps ranged between 68.5 ± 23.8 µm and 87 ± 29.1 µm while occlusal gaps ranged from 220.7 ± 33.3 µm to 275.5 ± 46.5 µm and were not significantly different between groups. Fracture loads ranged from 633.8 ± 127.3 N to 1596.4 ± 497.7 N with lithium disilicate glass ceramics (LDGCs) and Enamic having higher values than resin nano-ceramics (RNCs). The fracture resistance was more related to material than aging and gap value. CONCLUSION: The margin adaptation of resin ceramics was comparable to lithium disilicate with no significant difference. Lithium disilicate showed a higher resistance than resin ceramics and there was a higher resistance to fracture for polymer-infiltrated ceramic-network (PICN) than RNCs. CLINICAL SIGNIFICANCE: Resin ceramics can have marginal adaptation and fracture resistance within clinical acceptance; therefore, they can be a good chair-side solution achieved in a single appointment session.


Asunto(s)
Cerámica , Porcelana Dental , Cementación , Diseño Asistido por Computadora , Coronas , Ensayo de Materiales
12.
J Diabetes Metab Disord ; 18(1): 163-172, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31275887

RESUMEN

Background: A two-way relationship between diabetes and periodontitis is now clinically established. Both conditions share common mechanisms of pathogenesis that are related to altered immune-inflammatory responses at local and/or systemic levels. The aim of this study is to investigate whether periodontitis is associated with the development and progression of diabetes and to evaluate the health impact of coexistence of both diseases. Material and methods: Male Sprague Dawley rats (10 weeks old) were randomized into seven groups (n = 12): Group 1) Control; Groups 2 and 6) Periodontitis induced at two or six weeks; Groups 3 and 5) Diabetes induced at two or six weeks; Groups 4 and 7) Periodontitis followed by diabetes, and diabetes followed by periodontitis at two or six weeks. For diabetes induction, animals received a one-time intravenous injection of streptozotocin (50 mg/kg). Periodontitis was induced by Lipoppolysaccharide injection (20 µg/rat) through the palatal gingival and by placing a ligature of 0/0 braided silk around the cervix of the upper right second molar. Body weight, glycaemia as well as urine were collected weekly. Rats were sacrificed at the end of week 10, gingival tissue was removed, fixed in formaldehyde and processed for histopathological study. Results: Body weight was significantly decreased (25%) following diabetes induction (p < 0.01). 40% weight loss was observed when diabetes was induced first compared to 30% when periodontitis was first induced in the animals (p < 0.01). Rats treated with streptozotocin showed a three-fold increase in diabetes compared to the control group (p < 0.01). In rats where periodontitis was induced after diabetes, glucose levels increased significantly (450 mg/dL) compared to glucose levels (410 mg/dL) where periodontitis was induced first (p < 0.01). Histopathological studies showed greater alveolar bone loss when both diabetes and periodontitis were present. Conclusion: When periodontitis occurs after diabetes it aggravates the symptoms of the two pathologies. When diabetes is induced after periodontitis, no symptoms aggravation is observed for diabetes, although periodontitis gets worse.

13.
Clin Cosmet Investig Dent ; 11: 119-129, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31213925

RESUMEN

Purpose: The purpose of this laboratory study was to evaluate the effect of different surface treatment combinations on resin zirconia bonding. Materials and methods: One hundred and five pre-sintered zirconia quadrangles were prepared out of zirconia blocks, polished, then sintered and divided into five groups (n=21). Group I (control): samples were untreated, group II: grit-blasting with 50 µm alumina particles, group III: grit-blasting with 100 µm alumina particles, group IV: Er,Cr:YSGG laser, and group V: selective infiltration etching technique. Microstructural analysis was performed using scanning electron microscopy, atomic force microscopy, a diffractometer, and a profilometer. Cylinders of composite resin were luted with Panavia resin composite cementand Clearfil ceramic primer. Shear bond strength (SBS) was determined using a universal testing machine. Results: SBS results were analyzed using one-way ANOVA followed by Tukey post hoc tests for multiple comparisons. The level of significance was set to 0.05. SBS values of the studied groups II, III, IV, and V were 16.2±1.8 MPa, 15.7±3.7 MPa, 14.8±3.4 MPa, and 16.8±3.0 MPa, respectively. All values were significantly higher than the control group (10.48±1.80 MPa), but without a significant difference between them. Group III exhibited the roughest surface, and Group I had a more significantly reduced surface roughness value than any other group. Group III presented the highest significant increase of tetragonal to monoclinic phase transformation (13%). Conclusion: The use of grit-blasting with greater particles size enhanced SBS with resin composite cement, but induced a higher amount of monoclinic phase transformation. The use of primer based on adhesive monomer with the resin cement is required to enhance the bonding efficiency. The use of laser enhanced the surface roughness and the bonding ability to zirconia.

14.
J Esthet Restor Dent ; 31(4): 378-387, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-31067007

RESUMEN

OBJECTIVES: The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of endocrowns made of three computer-aided design/computer-aided manufacturing (CAD/CAM) materials subjected to thermo-mechanical cycling loading. MATERIALS AND METHODS: Eighty mandibular molars were divided into four groups (n = 20): one (C E) was restored with lithium disilicate glass-ceramic conventional crowns, three were restored with endocrowns made of three different CAD/CAM materials; (E E) lithium disilicate glass-ceramic, (E V) zirconia-reinforced lithium silicate glass-ceramic, and (E C) resin nano-ceramic. After cycling loading, half of the samples from each group were loaded axially and the other half was loaded laterally. Fracture resistance was recorded in Newton (N) and failure modes were classified. Two-way ANOVA, Bonferroni post hoc (α = .05), Chi-square, and multiple logistic regression tests were used to analyze data. RESULTS: Statistically significant interaction were recorded between fracture resistance (N) and loading (P < .001), and groups (conventuional crown and endocrowns; P < .001). Endocrowns presented higher fracture strength than conventional crowns. Fracture resistance was significantly larger under axial loading. The numbers of irreparable failures were extremely important in the endocrowns groups (Groups E E, E V, E C), and only conventional crowns (Group C E) showed almost no irreparable failures under axial loading. CONCLUSION: Lithium disilicate glass-ceramic recorded the highest fracture resistance under axial and lateral loading. CLINICAL SIGNIFICANCE: The number of irreparable failures with all endocrown materials tested do not suggest yet the use of this type of restorations in posterior teeth.


Asunto(s)
Diseño Asistido por Computadora , Porcelana Dental , Cerámica , Coronas , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Ensayo de Materiales , Diente Molar
15.
J Contemp Dent Pract ; 20(1): 56-63, 2019 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-31102396

RESUMEN

AIM: To evaluate the fracture resistance and failure pattern of custom made computer-aided design & computer-aided manufacturing (CAD/CAM) post and cores using a fiber reinforced composite material (FRC) and a high-density-polymer. MATERIALS AND METHODS: Thirty extracted mandibular second premolars were selected, endodontically treated and prepared to receive the posts. The specimens were randomly divided into three groups (n = 10) according to each material: group 1 (RXP) : fiber posts (Rely X, 3M-ESPE) with composite core build-up (Filtek Bulk Fill Posterior, 3M-ESPE) as a control group; group 2 (BLC): one-piece milled post and core from fiber reinforced composite blocks (Trilor, Bioloren); and group 3 (AMC): one-piece milled post and core from hybrid ceramic disks (Ambarino, Creamed). All the posts were cemented using a self-adhesive resin cement (Rely X U200, 3M ESPE). Fracture resistance was tested using a universal testing machine, failure patterns were then observed visually and radiographically then evaluated under SEM. Data was analyzed using One-way analysis of variance (ANOVA) followed by Tamhane post-hoc test in order to determine significant differences among groups (α = 0.05). RESULTS: The mean fracture resistance values were: 426.08 ± 128.26 N for group 1 (R X P), 367.06 ± 72.34N for group 2 (BLC), and 620.02 ± 54.29N for group 3 (AMC). Statistical analysis revealed that group 3 (AMC) had the highest mean load to fracture in comparison to the other groups (p = 0.000). failures were cohesive in group 2 and 3 and mixed in group 1 with no catastrophic failures reported in all groups. CONCLUSION: All systems evaluated presented sufficient mean load-to-failure values for endodontically treated teeth restorations. CAD/CAM post and cores made from high-density-polymer showed a better performance than prefabricated fiber posts.


Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes , Diente no Vital , Resinas Compuestas , Diseño Asistido por Computadora , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Proyectos Piloto
16.
J Investig Clin Dent ; 10(3): e12413, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31001919

RESUMEN

AIM: The aim of the present study was to evaluate the marginal and internal fit of zirconium fixed partial denture using different impression techniques. METHODS: A Nissin Typodont model, including maxillary central incisor and canine with missing lateral incisor, was selected for the present study. Thirty zirconium frameworks were fabricated following three impression techniques (N = 10), conventional silicone impression (group C), scanned dental impression (group S), and Trios 3 (3Shape) intraoral scanner (group T). An extra-fine milling strategy was applied. RESULTS: Group T had the smallest discrepancy compared to groups C (P = 0.006) and S (P = 0.052) at the marginal level, whereas it was larger at the incisal tip. Discrepancies in group T were smaller than group C (P = 0.004) when measured at the axial walls, and smaller than group S (P = 0.045) when measured at the chamfer area for the central teeth only. Samples in group T showed a greater percentage of equally extended restorations (52.5%), while other groups were mainly underextended (group C: 63.7%, group S: 68.8%). CONCLUSION: Better adaptation was achieved with the intraoral scanner group, except at the incisal tip. Conventional and scanned impressions revealed a greater percentage of underextended restorations.


Asunto(s)
Adaptación Marginal Dental , Circonio , Diseño Asistido por Computadora , Coronas , Técnica de Impresión Dental , Diseño de Prótesis Dental , Dentadura Parcial Fija
17.
Int J Comput Dent ; 22(1): 45-53, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30848254

RESUMEN

AIM: To evaluate the marginal adaptation and internal fit of milled fiber post and cores using different scanning methods. MATERIALS AND METHODS: Thirty typodont tooth models (Nissin) with pulp cavity were endodontically treated and prepared to receive 30 fabricated fiber post and cores. Three different methods of scanning were used (n = 10): an intraoral scanner (IOS) (Trios 3; 3Shape) to directly digitalize the post space (Group T) and a laboratory scanner to indirectly digitalize the resin pattern (Group RP) and the silicone impression (Group S) of the post space. All the specimens were examined using an optical microscope for the measurement of the vertical marginal discrepancy (VMD), and five in each group were scanned using microcomputed tomography (µCT) for the assessment of the VMD, the internal fit at the corner (IFC), post apex (PA), and at four horizontal cross-sections (CS1-4) inside the canal. All data were analyzed using mixed-design ANOVA, followed by pairwise testing to identify the differences (α = 0.05). RESULTS: Statistical analysis revealed that Group T was associated with the smallest cement space compared with Group RP (P = 0.001) and Group S (P < 0.001) for VMD using µCT or direct microscopy (OM) (P < 0.001). Similarly, the cement space for Group T was smaller than that of Group S (P = 0.039) when measured at the IFC (µCT), and smaller than Group RP (P = 0.025) when measured at CS1-4 (µCT), with CS1 larger than CS3 (P = 0.015). There was no significant difference at PA (P = 0.271). CONCLUSION: Better adaptation was achieved with a complete digital workflow. Scanning the resin pattern or the silicone impression introduced more variables in the digital process or milling of a one-piece fiber post and core.


Asunto(s)
Coronas , Adaptación Marginal Dental , Diseño Asistido por Computadora , Diseño de Prótesis Dental , Humanos , Microtomografía por Rayos X
18.
J Contemp Dent Pract ; 19(7): 816-823, 2018 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-30066685

RESUMEN

AIM: This study compared the bond strength of pre-sintered Ceramill Sintron to pre-sintered zirconia and cast nickel-chromium (NiCr). MATERIALS AND METHODS: Specimens (n = 60) (diameter: 15 mm; thickness: 2 mm) were prepared (n = 20/group) (Ceramill Sintron, Ceramill Zi, and Wirobond 99). Disks were layered with vita VM ceramic (4 mm). Specimens were randomly divided into two subgroups. Only one subgroup was thermocycled. Specimens were tested under shear strength. Energy-dispersive X-ray (EDX) mapping was done on one disk of each material before and after ceramic layering. RESULTS: Failure types were mostly mixed failures. Significant difference was found between the three materials for Y and Z failure types (p-values: 0.032 and 0.010 respectively). Thermocycling had no major effect on the results reported. Considering Fmax (force-inducing bonding failure) registered, significant difference was found between the control group and milled alloys groups. No significant difference was found between Ceramill Sintron and Zi. The EDX mapping showed a net increase in the control group oxide layer, whereas only slight increase and decrease were reported for Zi and Sintron respectively. CONCLUSION: When compared with cast NiCr, novel Ceramill Sintron has higher bond strength, comparable to Ceramill Zi. Thermocycling had no major effects on the results. CLINICAL SIGNIFICANCE: Ceramic-alloy bonding is a primary factor in the prosthesis' longevity.


Asunto(s)
Aleaciones de Cromo , Cromo , Recubrimiento Dental Adhesivo , Aleaciones de Cerámica y Metal , Níquel , Circonio , Diseño Asistido por Computadora , Porcelana Dental , Análisis del Estrés Dental , Ensayo de Materiales , Resistencia al Corte , Estrés Mecánico
19.
Biomed Res Int ; 2018: 1803425, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29992135

RESUMEN

This study evaluated the effect of air abrasion before and after sintering with different particle type, shape, and size on the surface morphology, monoclinic phase transformation, and bond strength between resin cement and zirconia surface using primer containing silane and MDP. Airborne particle abrasion (APA) was performed on zirconia before and after sintering with different particle shape and size (50 µm Al2O3 and 25 µm silica powder). 120 square shaped presintered zirconia samples (Amann Girrbach) were prepared (3 mm height × 10 mm width × 10 mm length) and polished with grit papers #800, 1000, 1200, 1500, and 2000. Samples were divided into 6 groups according to surface treatment-group A: (control) no surface treatment; group B: APA 50 µm Al2O3 before sintering (BS); group C: APA 50 µm Al2O3 after sintering (AS); group D: APA25 µm silica powder (BS); group E: APA25 µm silica powder (AS) at a pressure of 3.5 bar; and group F: APA 25 µm silica powder (AS) at a pressure of 4 bar. Samples were analyzed using XRD, AFM, and SEM. The samples were submitted to shear bond strength (SBS) test. A dual cure resin cement (RelyX Ultimate) and primer (Scotchbond Universal) were used. Data were analyzed with ANOVA and Tukey test (α ≥ 0.05). APA in group B significantly increased the surface roughness when compared to all other groups. A significant monoclinic phase transformation (t-m) value was observed in groups C and F and a reverse transformation occurred in presintered groups. The SBS value of group A was 11.58 ± 1.43 and the highest significant shear bond strength value was for groups B (15.86 ± 1.92) and C (17.59 ± 2.21 MPa) with no significant difference between them. Conclusions. The use of APA 50 µm Al2O3 before sintering and the application of primer containing MDP seem to be valuable methods for durable bonding with zirconia. The use of APA 50 µm Al2O3 after sintering induced the highest (t-m) phase transformation.


Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Circonio , Óxido de Aluminio , Materiales Dentales , Análisis del Estrés Dental , Ensayo de Materiales , Resistencia al Corte , Propiedades de Superficie
20.
J Prosthet Dent ; 120(3): 409-414, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-29724558

RESUMEN

STATEMENT OF PROBLEM: Limited information is available on the precision of new metal processing technologies. PURPOSE: The purpose of this in vitro study was to evaluate the marginal and internal fit of pre-sintered cobalt-chromium (Co-Cr) and zirconia 3-unit fixed dental prostheses using x-ray microcomputed tomography. MATERIAL AND METHODS: Three-unit fixed dental prostheses were prepared on metal dies (N=12) using a typodont model from the maxillary first premolar to the first molar. A standardized preparation with a 1.2-mm chamfer (360 degrees) and a 2-mm occlusal reduction was prepared on abutment teeth. The dies were scanned and divided into 2 groups to receive the fixed dental prostheses (n=6) made of pre-sintered Co-Cr and pre-sintered zirconia. Each framework was seated on its cast, and marginal and internal discrepancies were measured at 9 points, starting from the most distal point from the pontic for the maxillary first premolar and the first molar (points 1-4, mesial; point 5, occlusal; points 6-9, distal) of each abutment tooth using microcomputed tomography. The data were analyzed using the Levene test, t test, and ANOVA (α=.05). RESULTS: When overall mean discrepancy values were compared, no significant difference was observed between pre-sintered Co-Cr and pre-sintered zirconia (P=.085). Discrepancy values for points 1, 2, and 3 were significantly different for pre-sintered Co-Cr and pre-sintered zirconia, with the lowest mean values for point 1 and the highest for point 5. On the abutment tooth basis, for the maxillary first premolar and the first molar, a significant difference was found only in points 6 (P<.001) and 8 (P<.003) for both materials. When the discrepancies for the maxillary first premolar were considered for pre-sintered Co-Cr and pre-sintered zirconia, the mean values were significantly different only at points 1 (P<.001), 2 (P=.007), and 3 (P=.003) and were smaller for pre-sintered zirconia. For the tooth the first molar, a significant difference was observed at point 2 (P=.002) and point 3 (P=.008) for both materials, where the mean values were higher for pre-sintered Co-Cr than for pre-sintered zirconia. The pairwise comparison between points showed a significant difference between measurement points within each material (P<.05). The increase in values between points 1 and 5 was evident for both pre-sintered Co-Cr and pre-sintered zirconia materials. CONCLUSIONS: Three-unit fixed dental prostheses made of pre-sintered Co-Cr or zirconia showed similar marginal and internal discrepancy values, with the highest discrepancy values at the occlusal region in both the first premolar and first molar.


Asunto(s)
Adaptación Marginal Dental , Prótesis Dental , Aleaciones de Cromo/uso terapéutico , Diseño Asistido por Computadora , Diseño de Prótesis Dental , Humanos , Radiografía Dental , Microtomografía por Rayos X , Circonio/uso terapéutico
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA