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1.
Beijing Da Xue Xue Bao Yi Xue Ban ; 55(1): 108-113, 2023 Feb 18.
Artigo em Chinês | MEDLINE | ID: mdl-36718697

RESUMO

OBJECTIVE: To predict the learning curve of tooth preparation for all ceramic crowns of maxillary central incisors on phantom head simulators for graduate students participating in standardized dental resident training based on the modified Wright learning curve model, then to analyze and applicate the learning curve. METHODS: Twelve graduate students participating in standardized dental resident training were selected to prepare the resin maxillary central incisors on phantom head simulators for all ceramic crowns 4 times. The results of preparation were evaluated by 3 prosthetic experts with at least 10 years' experience focusing on the reduction, contour, taper, shoulder, finish line, margin placement, adjacent tooth injury, and preparation time for tooth preparation. The learning rate of tooth preparation was calculated by scores of tooth preparation of 4 times. The learning curve of tooth preparation was predicted based on the modified Wright learning curve model. According to the criteria of standardized training skill examinations for dental residents in Beijing, 80 was taken as the qualified standard score. The minimum training times for tooth preparation to satisfy the qualified standard score (80) was calculated, to analyze the characteristics of learning curve and evaluate the effectiveness of tooth preparation. RESULTS: The scores of 4 tooth preparation were 64.03±7.80, 71.40±6.13, 74.33±5.96, and 75.98±4.52, respectively. The learning rate was (106±4)%, which showed the learning curve an upward trend. There were no significant differences between the qualified standard score and the predicted scores of tooth preparation from the 5th preparation to the 13th preparation (P > 0.05). The predicted score of the 14th preparation was higher than the qualified standard score (P < 0.05). CONCLUSION: The trend of the learning curve of tooth preparation for all ceramic crowns of maxillary central incisors on phantom head simulators for graduate students participating in standardized dental resident training is upward, which predicts the minimum training times higher than the qualified standard score is 14 times.


Assuntos
Incisivo , Preparo Prostodôntico do Dente , Humanos , Preparo Prostodôntico do Dente/métodos , Curva de Aprendizado , Coroas , Preparo do Dente , Cerâmica , Porcelana Dentária , Planejamento de Prótese Dentária
2.
Br Dent J ; 234(1): 16-18, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36639466
3.
Compend Contin Educ Dent ; 44(1): e10-e14, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36649498

RESUMO

As patient demand for faster, streamlined, and convenient treatments increases, clinicians need to be prepared to provide accurate, esthetic, and predictable restorative solutions that meet these requirements. Among the many options currently available in coronal treatments utilizing a digital workflow, the author's practice has found that the use of a certain lithium-disilicate block in tandem with a self-adhesive resin cement provides such a solution. This case report demonstrates the use of CAD/CAM dentistry with in-office milling to restore a failed No. 14 full-coverage crown.


Assuntos
Coroas , Planejamento de Prótese Dentária , Humanos , Estética Dentária , Porcelana Dentária , Desenho Assistido por Computador , Teste de Materiais , Cerâmica
4.
Sci Rep ; 13(1): 1561, 2023 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-36709380

RESUMO

The current multiphase, invitro study developed and validated a 3-dimensional convolutional neural network (3D-CNN) to generate partial dental crowns (PDC) for use in restorative dentistry. The effectiveness of desktop laser and intraoral scanners in generating data for the purpose of 3D-CNN was first evaluated (phase 1). There were no significant differences in surface area [t-stat(df) = - 0.01 (10), mean difference = - 0.058, P > 0.99] and volume [t-stat(df) = 0.357(10)]. However, the intraoral scans were chosen for phase 2 as they produced a greater level of volumetric details (343.83 ± 43.52 mm3) compared to desktop laser scanning (322.70 ± 40.15 mm3). In phase 2, 120 tooth preparations were digitally synthesized from intraoral scans, and two clinicians designed the respective PDCs using computer-aided design (CAD) workflows on a personal computer setup. Statistical comparison by 3-factor ANOVA demonstrated significant differences in surface area (P < 0.001), volume (P < 0.001), and spatial overlap (P < 0.001), and therefore only the most accurate PDCs (n = 30) were picked to train the neural network (Phase 3). The current 3D-CNN produced a validation accuracy of 60%, validation loss of 0.68-0.87, sensitivity of 1.00, precision of 0.50-0.83, and serves as a proof-of-concept that 3D-CNN can predict and generate PDC prostheses in CAD for restorative dentistry.


Assuntos
Desenho Assistido por Computador , Coroas , Humanos , Redes Neurais de Computação , Preparo do Dente , Assistência Odontológica , Imageamento Tridimensional/métodos
5.
Gen Dent ; 71(1): 54-57, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36592360

RESUMO

Ceramic chipping occurs frequently in veneered all-ceramic crowns, and the decision to repair or replace them depends on many factors. The least invasive method is the intraoral repair. This case report describes a conservative restorative treatment performed on a chipped dental crown. A 59-year-old patient fractured her all-ceramic crown, revealing chipping and debonding of the feldspathic ceramic veneer and exposure of the zirconia framework. The fractured fragment was brought to the dental office. Due to the patient's esthetic concerns about prolonged treatment, it was decided to use the fragment to repair the crown intraorally. The result exceeded the patient's expectations. The intraoral repair of a chipped all-ceramic crown is a conservative and low-cost alternative that allows for immediate restoration of the function and esthetics. It is essential to establish protocols that can support clinician decision-making about the most appropriate clinical treatment, seeking the longevity of the restoration and the dental structure.


Assuntos
Coroas , Porcelana Dentária , Humanos , Feminino , Pessoa de Meia-Idade , Porcelana Dentária/química , Cerâmica/química , Zircônio/química , Protocolos Clínicos , Facetas Dentárias , Falha de Restauração Dentária
6.
Rev. flum. odontol ; 1(60): 147-160, jan.-abr. 2023. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1411400

RESUMO

Introduction: The goal of this pilot study was to evaluate the differences between checking occlusion on implants crowns using 16 or 200 µm thickness of articulating occlusal paper, and to compare the stained occlusal area between the groups after bite forces of 200 and 250 N. Methods: It was included 10 casts of articulated-type IV gypsum, 10 NiCr crowns, articulating occlusal papers (16 µm and 200 µm thick), and a compression test machine. Compressive forces (200 and 250 N.mm) were applied on models, to check the occlusal contact area of fixed and cemented crowns. The contact areas on the crowns were measured through images obtained by the scanning electron microscope. Statistical tests were performed considering the significant level of 5% (p≤0.05). Results: The stains found using 200 µm of articulating paper were higher than those with 16 µm, independent of the force applied. However, the stains obtained in lower teeth with different strengths (200 and 250N) marked with 16 µm articulating paper were not possible to score. The articulating paper variable had significant statistical results (p=0.002), while the variables force (p=0.443) and articulating paper-force interaction (p=0.607) were not significant. The mean area found in staining using the 200 µm and 16 µm papers was, respectively, 8.3380 mm2 and 3.4759 mm2. Conclusion: It was possible to confirm that 200 µm of articulating occlusal paper showed better and significant results to stain the occlusal area, permitting a more accurate adjustment independent of the force applied.


Assuntos
Força de Mordida , Implantes Dentários , Força Compressiva , Coroas , Articuladores Dentários , Oclusão Dentária , Dente Molar
7.
J Mech Behav Biomed Mater ; 138: 105629, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36535094

RESUMO

Functionally graded materials (FGMs) - categorized in advanced composite materials - are specially designed to reduce the stresses and failure due to material mismatches. Advances in manufacturing techniques have brought FGMs into use in a variety of applications. However, the numerical analysis is still challenging due to the difficulties in simulations of non-homogeneous material domains of complex parts. Presenting a numerical procedure that both facilitates the implementation of material non-homogeneity in geometrically complex mediums, and increases the accuracy of the calculations using a phase-field approach, this study investigates the usage of FGMs in dental prostheses. For this purpose, a porcelain fused to metal (PFM) mandibular first molar FGM crown is simulated and analyzed under the maximum masticatory bite force, and eventually the results are compared to a PFM crown prepared conventionally.


Assuntos
Coroas , Metais , Análise de Elementos Finitos , Mandíbula , Porcelana Dentária , Análise do Estresse Dentário
8.
J Prosthet Dent ; 129(1): 61-68, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36535882

RESUMO

STATEMENT OF PROBLEM: Clinical data on orthodontic extrusion to restore teeth deemed unrestorable because of their defect size are scarce. It remains unclear for which defects forced orthodontic extrusion and tooth retention is preferred to extraction. PURPOSE: The purpose of this pilot clinical study was to investigate the survival, frequency, and type of complications of extensively damaged teeth requiring single-crown restorations after forced orthodontic extrusion. MATERIAL AND METHODS: Participants were recruited from consecutive patients in need of restorative treatment of extensively damaged teeth at a university clinic. The teeth were orthodontically extruded to reestablish the biologic width and to ensure a 2-mm ferrule preparation before restoration. The primary endpoint was restoration success and survival. At recall, survival was defined as the tooth being in situ and success as a symptom-free tooth with an intact, caries-free restoration and with physiological pocket probing depths, no signs of intrusion, ankylosis, root resorption, or periapical radiolucency. Recalls were performed every 6 months; the outcome was assessed by radiographic and clinical evaluation after up to 5 years of clinical service. Quantitative parameters were described with mean values and standard deviations. RESULTS: Thirty-four participants were assessed for eligibility and enrolled (mean ±standard deviation age: 53.4 ±18.9 years). Four participants were premature dropouts. Data were analyzed for 35 teeth in 30 participants. The amount of extrusion varied between 2 and 6 mm (mean ±standard deviation 3.4 ±0.9 mm). The mean duration of extrusion was 18.9 ±12.6 days and the mean duration of retention was 126.94 ±88.1 days. The mean ±standard deviation crown-to-root ratio after treatment was 0.8 ±0.1 (range: 0.5 to 1.0). Three participants exhibited orthodontic relapse before restoration. Teeth were successfully restored after repeated extrusion. After a mean observation period of 3.3 years (range: 1 to 5.2 years), 29 of 31 teeth were still in situ. Two teeth were fractured, and 4 participants were not available for recall. Thus, the survival rate was 94%. No resorption or periapical translucencies were observed radiographically. Clinical examinations revealed physiological probing depths and absence of ankyloses. One tooth presented with marginal bone loss. The most frequent type of complication was orthodontic relapse at recall (n=3). A total of 84% of teeth were considered a success. CONCLUSIONS: Forced orthodontic extrusion allowed for the restoration of anterior and premolar teeth deemed as nonrestorable because of their defect size. Tooth retention of extensively damaged teeth and their use as abutments for single-crown restorations can be recommended.


Assuntos
Extrusão Ortodôntica , Coroa do Dente , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Extrusão Ortodôntica/métodos , Dente Pré-Molar , Coroas , Recidiva
9.
Dent Mater ; 39(1): 86-100, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36503862

RESUMO

OBJECTIVE: To seek dentine analogue materials in combined experimental, analytical, and numerical approaches on the mechanical properties and fatigue behaviours that could replace human dentine in a crown fatigue laboratory test. METHODS: A woven glass fibre-filled epoxy (NEMA grade G10; G10) and a glass fibre-reinforced polyamide-nylon (30% glass fibre reinforced polyamide-nylon 6,6; RPN) were investigated and compared with human dentine (HD). Flexural strength and elastic modulus (n = 10) were tested on beam-shaped specimens via three-point bending, while indentation hardness (n = 3) was tested after fracture. Abutment substrates of G10, RPN and HD were prepared and resin-bonded with monolithic lithium disilicate crowns (n = 10), then subjected to wet cyclic loading in a step-stress manner (500 N initial load, 100 N step size, 100,000 cycles per step, 20 Hz frequency). Data were statistically analysed using Kruskal-Wallis one-way ANOVA followed by post-hoc comparisons (α = 0.05). Survival probability estimation was performed by Mantel-Cox Log-Rank test with 95% confidence intervals. The fatigue failure load (FFL) and the number of cycles until failure (NCF) were evaluated with Weibull statistics. Finite Element Models of the fatigue test were established for stress distribution analysis and lifetime prediction. Fractographic observations were qualitatively analysed. RESULTS: The flexural strength of HD (164.27 ± 14.24 MPa), G10 (116.48 ± 5.93 MPa), and RPN (86.73 ± 3.56 MPa) were significantly different (p < 0.001), while no significant difference was observed in their flexural moduli (p = 0.377) and the indentation hardness between HD and RPN (p = 0.749). The wet cyclic fatigue test revealed comparable mean FFL and NCF of G10 and RPN to HD (p = 0.237 and 0.294, respectively) and similar survival probabilities for the three groups (p = 0.055). However, RPN promotes higher stability and lower deviation of fatigue test results than G10 in Weibull analysis and FEA. SIGNIFICANCE: Even though dentine analogue materials might exhibit similar elastic properties and fatigue performance to human dentine, different reliabilities of fatigue on crown-dentine analogues were shown. RPN seems to be a better substrate that could provide higher reliability and predictability of laboratory study results.


Assuntos
Cerâmica , Nylons , Humanos , Cerâmica/química , Reprodutibilidade dos Testes , Teste de Materiais , Propriedades de Superfície , Análise do Estresse Dentário , Porcelana Dentária/química , Coroas , Dentina , Desenho Assistido por Computador
10.
Dent Mater ; 39(1): 114-122, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36566152

RESUMO

OBJECTIVE: This study aimed to evaluate the influence of new resin-based CAD-CAM implant-supported materials on posterior crown restoration stress and strain concentrations. METHODS: A previous 3D implant model was edited to receive a cement-retained posterior crown manufactured with different CAD/CAM materials (Estelite P Block, Estelite Block II or Estelite Layered Block). Each solid model was exported to the computer-aided engineering software and submitted to the finite element analysis of stress and strain. Material properties were assigned to each solid with isotropic and homogeneous behavior according to the manufacturer information. A vertical load of 600 N was applied in the occlusal region of the crown, via a simulated food bolus, and stress was calculated in Von Misses (σVM) for the implant, abutment and screw, Maximum (σMAX) Principal Stresses for the crown and microstrain for the bone. RESULTS: All simulated materials showed acceptable stresses levels with a similar stress pattern among the models. At the crown intaglio region and cement layer, however, differences were observed: Estelite P Block showed a lower tensile and shear stresses magnitude when compared to other resin-based materials with lower elastic modulus. SIGNIFICANCE: The stress effect of different resin-based CAD-CAM implant-supported crowns is predominant in the crown and cement layer, with Estelite P Block showing 7.4 % versus 9.3 % and 9.2 % for Estelite Block II and Estelite Layered Block of crown failure risk.


Assuntos
Implantes Dentários , Porcelana Dentária , Coroas , Materiais Dentários , Cimentos Dentários , Desenho Assistido por Computador , Análise do Estresse Dentário , Prótese Dentária Fixada por Implante , Análise de Elementos Finitos , Teste de Materiais , Planejamento de Prótese Dentária
11.
Braz. j. oral sci ; 22: e237338, Jan.-Dec. 2023. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1397295

RESUMO

Aim: Endocrown restorations are commonly used to rehabilitate endodontically treated posterior teeth and their use is well-founded in these cases. However, to date, there is little scientific evidence of their behavior in anterior teeth. The aim of this in vitro study was to evaluate the compressive strength of upper central incisors teeth, restored with glass-ceramic total crowns by the conventional anatomical core technique, and compare them to teeth restored with endocrowns with and without the presence of ferrule. Methods: Thirty teeth were randomly distributed into three groups: GE2 - endocrown group with 2 mm ferrule, GE0 - endocrown group without a ferrule, and GC - conventional crown with intraradicular post group. Crowns were cemented and teeth submitted to the 45o compression test until the fracture happened. Fractured specimens were analyzed to determine the fracture pattern. Descriptive analysis of the variables was performed and one-way analysis of variance was utilized to analyze the data for significant differences at p < 0.05. Results: The results of the control group (284.5 ± 201.05N) showed the highest fracture resistance value, followed by the 2mm group (274.54 ± 199.43N) and by the 0mm group (263.81 ± 80.05N). There was no statistically significant difference between all the groups (p = 0.964). Conclusions: The absence of a cervical enamel necklace favored a debonding of the pieces and endodontically treated anterior teeth could be restored with endocrown, which could be considered a conservative and viable treatment option


Assuntos
Desenho Assistido por Computador , Coroas , Endodontia , Resistência à Flexão
12.
BMC Oral Health ; 22(1): 550, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36456927

RESUMO

BACKGROUND: In clinical settings, tooth preparation for prefabricated zirconia crowns (PZCs) in the primary dentition varies widely. However, knowledge about the biomechanical behavior of PZCs in various clinical settings is limited. This study was conducted to evaluate the biomechanical behavior of PZCs in different clinical settings using 3-dimensional finite element analysis. METHODS: 3-dimensional models of the PZC, cement, and tooth with six different conditions were simulated in primary molar teeth, incorporating cement thickness (100, 500, and 1000 µm) and cement type (resin-modified glass ionomer cement and resin cement). A total of 200 N of occlusal force was applied to the models, both vertically and obliquely as representative cases. A general linear model univariate analysis with partial eta-squared (ηp2) was performed to evaluate the relative effects of the variables. RESULTS: The overall stress of tooth was increased as the cement space increases under oblique loading. The von Mises stress values of the resin cements were significantly higher than those of the resin-modified glass ionomer cements for all cement thicknesses (p < .05). The effect size of the cement type (ηp2 = .519) was more dominant than the cement thickness (ηp2 = .132) in the cement layer. CONCLUSIONS: Within the limits of this study, cement type has a greater influence on the biomechanical behavior of PZCs than cement thickness.


Assuntos
Cimentos Dentários , Preparo do Dente , Humanos , Criança , Análise de Elementos Finitos , Cimentos de Ionômeros de Vidro , Materiais Dentários , Cimentos de Resina , Coroas
13.
Int J Nanomedicine ; 17: 6551-6560, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36575697

RESUMO

Objective: Mid-to-long term use of provisional crowns in the oral cavity is associated with bacterial adhesion and biofilm formation, thus necessitating provisional crowns exhibiting antibacterial properties to prevent the occurrence of gingivitis and periodontal disease. This study aimed to evaluate the antibacterial effect of zirconia nanoparticle-containing polyethyl methacrylate (PEMA) resin for provisional restorations. Methods: Zirconia nanoparticles were added to the monomer of PEMA resin for provisional restorations, and the mixture was stirred for 2 h using a magnetic stirrer. Disk-shaped specimens were prepared by mixing the polymer with the nanoparticle solution. The control group contained pure PEMA resin samples, and the experimental groups Group Z2, Group Z4, and Group Z8 included PEMA resin specimens containing 2, 4, and 8% w/v zirconia nanoparticles, respectively. After analyzing the sample surfaces, the antibacterial effect of the specimens was evaluated using Streptococcus mutans. Statistical analysis was performed using Tukey's test and Mann-Whitney U-test, according to the normality result in the Shapiro-Wilk test. Results: FE-SEM and EDX analyses revealed the successful addition of zirconia nanoparticles. Results showed no significant difference in the measured values for surface roughness and contact angle between the experimental and control groups; however, adhesion and biofilm thickness of S. mutans were significantly decreased in Group Z2, Group Z4, and Group Z8 compared to the control group (P < 0.05, P < 0.01, P < 0.01, respectively). Conclusion: The addition of zirconia nanoparticles can lower the incidence of adhesion and biofilm thickness of S. mutans on PEMA resin used for provisional crowns. Thus, incorporating zirconia nanoparticles in repair materials for provisional crowns and PEMA resin can produce an antibacterial effect and prevent gingivitis, periodontal disease, and dental caries.


Assuntos
Cárie Dentária , Gengivite , Nanopartículas , Doenças Periodontais , Humanos , Metacrilatos , Zircônio/farmacologia , Antibacterianos/farmacologia , Resinas Vegetais , Coroas , Teste de Materiais , Propriedades de Superfície
14.
J Indian Prosthodont Soc ; 22(1): 97-103, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36510953

RESUMO

Postextraction immediate implant placement in the esthetic zone is a common treatment modality. Immediate fixed interim restoration following immediate implant placement may provide excellent esthetic results to the patients and boost the clinicians' confidence. This paper demonstrates a series of six different techniques used to fabricate the customized screw-retained interim restorations following immediate implant placement with partial extraction therapy in the maxillary anterior esthetic zone. The techniques have utilized a putty index, polycarbonate shell crown, patients' existing crowns (prosthetic or natural), or laminate veneer, or fabricated in the laboratory based on the specific clinical situation. Advantages and limitations of each technique including alternative techniques or materials have been discussed. Excellent esthetic results were obtained with all six techniques using the screw-retained immediate interim restorations following partial extraction therapy and immediate implant placement.


Assuntos
Implantes Dentários para Um Único Dente , Implantes Dentários , Humanos , Estética Dentária , Coroas , Coroa do Dente
15.
Int J Prosthodont ; 35(5): 697-701, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36511795

RESUMO

PURPOSE: To evaluate the fit and trueness of temporary crowns fabricated with 3D printing vs milling technologies and to analyze any existing correlations between fit and trueness. MATERIALS AND METHODS: Marginal and internal fit and trueness were evaluated. Groups were compared using Kruskal-Wallis H test (α = .05), and correlations were analyzed using Spearman rank correlation analysis (α = .0016). RESULTS: Intaglio surface trueness was partially correlated with the marginal and internal fit (P < .0016). CONCLUSION: High intaglio surface trueness in the axial and occlusal regions may result in poor marginal fit. In the axial region, high intaglio surface trueness may adversely affect both the marginal and internal fit.


Assuntos
Coroas , Adaptação Marginal Dentária , Estereolitografia , Desenho Assistido por Computador , Planejamento de Prótese Dentária , Impressão Tridimensional
16.
Prim Dent J ; 11(4): 71-76, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36533368

RESUMO

PURPOSE: The purpose of this systematic review was to compare the clinical performance of lithium disilicate (LDS) and zirconia (Z) single crowns manufactured by computer-aided design/computer-aided manufacturing (CAD/CAM) systems using intraoral optical scanners (IOS). MATERIALS AND METHODS: An electronic search for articles published between January 2012 and January 2022 in the English language was performed with the Medline/Pubmed database under the guidelines of Preferred Reporting Items for Systemic Reviews and Meta-analysis (PRISMA). The specific search terms used were "zirconia", "lithium disilicate", "CAD/CAM", "intraoral optical scanner", and "survival". RESULTS: The initial electronic search resulted in 278 articles. Most of the resulting articles were excluded, six clinical studies addressing the clinical outcomes of Z and LDS crowns fitted the inclusion criteria and were selected for review. Of these six studies, three were randomised controlled trials, two were retrospective studies, and one was a prospective study. To quantify the clinical performance of the crowns several parameters were recorded, including fractures, endodontic complications, periodontal complications, technical complications, aesthetic complications, and biological complications. It was noted that the most common technical complication of Z and LDS crowns was chipping at a rate of 1.4% and 5% respectively. Regarding Z crowns, aesthetic concerns were the most frequently observed complication. CONCLUSION: The outcomes of this systematic review indicate that Z and LDS crowns display a similar incidence of periodontal and endodontic complications when compared to metal-ceramic crowns, suggesting that these all-ceramic materials are viable alternatives. The incidence of chipping was higher in LDS crowns compared to other materials, while Z crowns were inferior in terms of aesthetics.


Assuntos
Planejamento de Prótese Dentária , Lítio , Humanos , Cerâmica , Desenho Assistido por Computador , Coroas , Porcelana Dentária , Estudos Prospectivos , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Retrospectivos , Zircônio
17.
Int J Prosthodont ; 35(5): 676-683, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36511792

RESUMO

PURPOSE: To compare the effect of thermomechanical aging on implant abutment color change when using different abutment backgrounds. MATERIALS AND METHODS: In this study, three separate experimental groups (n = 10) with different implant abutment materials were used: zirconia, modified polyether ether ketone (MPEEK), and polyether ketone ketone (PEKK). Equal-sized glass-ceramic incisor crowns were cemented to the abutments using transparent dual-curing resin cement. The specimens were then subjected to the thermomechanical aging process for the clinical equivalent of 5 years of use. The color values of each specimen in the middle third and the incisal third were recorded by a digital spectrophotometer in the CIE L*a*b* color coordinates both before and after the aging process. Color differences between groups were compared using one-way analysis of variance (ANOVA), while Tukey test was used to compare differences within the groups (P = .05). RESULTS: In terms of color change (ΔE00) values, the zirconia group was found to show statistically more color changes only in the middle third (P < .000), but there was no significant difference between the the MPEEK and PEKK groups. In all groups, the ΔE00 value was clinically acceptable (ΔE00 < 1.8). CONCLUSION: After the aging process, high-performance polymer abutments caused less color change than zirconia. Therefore, esthetically satisfying results can be obtained in the anterior region, especially when highly translucent crown materials are used.


Assuntos
Dente Suporte , Zircônio , Cerâmica , Coroas , Materiais Dentários , Cetonas , Teste de Materiais , Cor , Porcelana Dentária
18.
Evid Based Dent ; 23(4): 166-167, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36526847

RESUMO

Data sources Electronic search through PubMed (Medline), CENTRAL (Cochrane) and Embase databases in November 2021. Grey literature searches (OpenGrey, Pro-Quest, National research register and the register of clinical studies hosted by the US National Institute of Health).Study selection Randomised in vivo clinical trials (RCTs) with at least two-year follow-ups, that compared the longevity of adhesively luted indirect ceramic restorations against conventionally cemented indirect metal restorations. The teeth studies had to be about single tooth restorations, on premolars or molars, with sufficient information available for extraction; eg outcome assessment, reason for failure. No language or time restrictions were applied.Data extraction and synthesis Two authors performed study selection, data extraction and quality assessment independently and in duplicate. The following clinical data was extracted: number of participants and dental health status, location of the cavosurface margin, cavity type, reason for intervention, methods and materials for treatment, follow-up, lesion activity at moment of restoration placed, lesion extension (surfaces of restoration), lesion margin (enamel or dentine). It was decided if the restoration was renewed, repaired or re-cemented, then this was classed as outcome failure. Grading of evidence was performed according to the GRADE network.Results After duplicates were removed, 2,667 underwent title screening, 389 abstract screening, and 186 went on to have full text screening with 72 being excluded. In total, 110 eligible articles were then excluded from the 114 that were assessed leaving four RCTs meeting the eligibility criteria and being included in the synthesis, published between 2000 and 2013. Two studies were parallel-arm, the other two, split-mouth design. Overall, 443 restorations had been placed, 212 were adhesively luted ceramic, and 213 conventionally cemented metal restorations; these were all gold. The follow-up periods ranged from 5-7 years. Two studies compared inlays only, one looked at partial crowns only, and the fourth full crowns. The lowest failure rates were found for metal restorations, ranging from 0-11%. The failure rates for ceramic inlays and partial crowns were 5-9% over the same observation period. The failure rates for ceramic full crowns were 36% after five years. The most common failure for ceramic was found to be fracture of the restoration, whereas caries was the most frequent cause of failure for the gold restorations.Conclusions The risk of bias was high for all four studies and the grading of evidence showed a low level of evidence. Only one meta-analysis could be performed comparing conventionally cemented metal vs adhesively luted ceramic restorations, showing the relative risk to fail for conventionally cemented metal indirect restorations is significantly lower than adhesively luted ceramic indirect restorations.


Assuntos
Cárie Dentária , Restauração Dentária Permanente , Humanos , Restauração Dentária Permanente/métodos , Coroas , Ouro , Restaurações Intracoronárias , Cerâmica , Cárie Dentária/terapia , Falha de Restauração Dentária
19.
J Indian Prosthodont Soc ; 22(4): 361-367, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36511070

RESUMO

Aim: Comparative evaluation of the fracture resistance of anterior provisional crowns fabricated by conventional and digital techniques. Settings and Design: Department of Prosthodontic, PGIDS, Rohtak, An in-vitro - Comparative study. Materials and Methods: Thirty recently extracted maxillary central incisors were handpicked. Tooth preparation was done according to the principles of tooth preparation. A single-step impression technique was used for impression making of the prepared tooth and stone models were poured. Extracted teeth were divided into 3 groups (n = 10 each) based on provisional crown fabrication technique. A bis-acryl-based (Protemp 4 3M ESPE) resin was used to fabricate the provisional crowns by the conventional indirect technique. The rest of the stone models (20) were scanned using lab scanner (Dentsply Sirona InLab EOS X5). CAD/CAM provisional material (Dentsply Sirona multilayer PolyMethyl Methacrylate) PMMA disc was used for fabrication of provisional restoration through milling technique. 3D printed temporary provisional material (NextDent C&B resin) was utilized for 3D printed provisional crowns. Cementation of provisional crowns was done using eugenol free temporary luting cement (Templute, Prime dental). All cemented provisional crowns were subjected to load under Universal Testing Machine. The maximum load to produce fracture for each specimen was recorded in Newton (N). Statistical Analysis Used: Shapiro-Wilk test was employed to test the normality of data. Kruskal- Wallis Test was used to compare the mean fracture resistance between all the groups. For intergroup comparison Mann-Whitney U Test was used. Results: The mean fracture resistance of group I (Conventional technique) was found to be 558.8459700 ± 22.33 N; for group II (CAD/CAM technique) 960.8427200 ± 37.49 N and for group III (3D Printed technique) 1243.1774000 ± 68.18 N. Group I had the least fracture resistance value while group III showed maximum value. Conclusion: Provisional crowns fabricated using 3-D printing technique showed higher fracture resistance followed by CAD/CAM technique and conventional technique. Additive manufacturing of provisional crowns using 3-D printing technique could be considered a reliable and conservative method for the fabrication of stronger provisional restorations.


Assuntos
Porcelana Dentária , Planejamento de Prótese Dentária , Teste de Materiais , Coroas , Desenho Assistido por Computador , Polimetil Metacrilato
20.
Braz. j. oral sci ; 21: e225136, jan.-dez. 2022. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1354771

RESUMO

Aim: To evaluate the influence of cobalt-chromium (Co-Cr) coping fabrication methods and ceramic application on the marginal and internal fit of metal-ceramic crowns. Methods: Co-Cr copings for metal-ceramic crowns were prepared by lost wax casting or CAD-CAM machining of sintered blocks. The fit was analyzed using the silicone replica technique at four assessment points: marginal gap (MG), axial wall (AW), axio-occlusal (AO) angle, and central occlusal (CO) wall. After the initial analysis, the copings were ceramic-veneered with the layering technique, and the fit was again determined. Data were statistically analyzed by paired and unpaired Student's-t test (α=0.05). Results: Marginal and internal fit before ceramic application according to the coping manufacturing method showed significant differences only at CO (p < 0.001), with milled copings (137.98±16.71 µm) showing higher gap values than cast copings (112.86±8.57 µm). For cast copings, there were significant differences at MG (before 109.13±8.79 µm; after 102.78±7.18 µm) and CO (before 112.86±8.57 µm; after 104.07±10.63 µm) when comparing the fit before and after ceramic firing. For milled copings, there was significant difference only at AO (before 116.39±9.64 µm; after 108.54±9.26 µm). Conclusion: This study demonstrated that the coping fabrication method influenced the internal fit. Ceramic firing maintained or improved the fit of the metal-ceramic crowns. The marginal discrepancy of all restorations, before and after ceramic firing, can be considered clinically acceptable


Assuntos
Cerâmica , Ligas Metalo-Cerâmicas , Adaptação Marginal Dentária , Coroas
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