ABSTRACT
Objective@#To analyze the effects of different restorations and the thickness of the occlusal space on the stress distribution of endodontically treated molars with endocrowns.@*Methods @# The finite element model of the restoration of the first mandibular molar was created, and four different endocrown materials were used including two resin based ceramics (Lava Ultimate, Vita Enamic), one lithium disilicate ceramic (IPS e.max CAD) and one zirconia ceramics (Cercon), and four kinds of surface space thickness were designed: 1 mm, 2 mm, 3 mm and 4 mm. A total of 600 N was loaded to simulate the maximum bite force in the vertical and inclined directions, and the finite element software ANSYS 10.0 was used to analyze the stress distribution@*Results@#The vertical loading analysis showed that the crown stress of the 1 mm-Cercon group was the highest at 211.30 MPa, and that of the 4 mm-Lava Ultimate group was the lowest at 11.56 MPa; the highest dentin stress was 38.84 MPa in the 3 mm-Lava Ultimate group, and the lowest was 11.68 MPa in 1 mm-Cercon group. The stress in the periodontal ligament and alveolar bone had little change. The inclined loading analysis showed that the crown stress of the 1 mm-Cercon group was the highest at 78.73 MPa and that of the 1 mm-Lava Ultimate group was the lowest at 35.51 MPa; the highest dentin stress was 41.63 MPa in the 1 mm-Cercon cervical group, and the lowest was 10.81 MPa in the 4 mm-Cercon coronal group. The stress concentration of cement and cervical dentin under inclined loading was higher than that under vertical loading.@* Conclusion @# The results of finite element analysis show that the elastic modulus of the endocrown increases, the stress of the crown restoration shows an upward trend, and the stress in the tooth shows a downward trend. With increasing crown thickness, the stress of the crown prosthesis decreased.
ABSTRACT
Objective:To investigate the wear characteristics of bovine enamel and lithium disilicate glass ceramic under simulated oral environment.Methods:18 cylindrical lithium disilicate glass-ceramic specimens with the length of 8 mm and diameter of 3 mm were randomly divided into 2 groups (n =9),9 lithium disilicate glass-ceramic specimens and 9 bovine enamel specimens were served as the antagonists respectively.The specimens were then loaded in a wear simulator and subjected to friction force of 10 N for 540 000 cycles in artificial saliva and room temperature(speed 100 r/min,turning radius of 2.5 mm,uniform circular motion) condition.During the testing,10 checkpoints were applied to measure the height loss of the specimens with 3D profilometer,then wear curves were plotted.Scanning electron microscopy were applied to investigate the worn surfaces at different wear stages.Results:At every checkpoints,bovine enamel wear height loss was larger than the lithium disilicate specimens (P ＜ 0.05);bovine enamel wear curve exhibits a runningin period,steady wear period and severe wear period 3 stages of wear,while wear curves of lithium disilicate glass ceramics exhibit onlyrunning-in period and steady wear period 2 wear stages.Both groups had the corresponding micro-morphological features in different periods.Conclusion:Bovine enamel and lithium disilicate glass ceramics show a phase dynamic evolution law under the simulated oral environment.Bovine enamel is more susceptible to wear than lithium disilicate,suggesting that clinical attention should be paid to prevent the excessive wear of natural teeth caused by lithium disilicate glass ceramic restorations.
ABSTRACT
A escolha dos materiais e dos passos do tratamento exigidos somente deverá ser iniciada quando as metas finais do tratamento estiverem totalmente definidas. Desse modo, será possível obter-se sincronização entre eles, para possibilitar resultado com sucesso. Nesta segunda parte do artigo, os autores mostram um modo sistemático para a confecção de reabilitações orais em casos complexos. A primeira parte deste artigo tratou do eficiente planejamento e da seleção de materiais cerâmicos apropriados, esta segunda parte é dedicada aos procedimentos da fabricação e incorporação de restaurações extensas.
Only if the treatment goals have been well defined before the treatment is started may the range of materials and the required treatment steps be synchronized with each other and streamlined towards a successful outcome. In this two-part article Prof. Dr Daniel Edelhoff and Oliver Brix present a systematic way to the full-mouth rehabilitation of complex cases. The first part deals with the efficient planning and targeted selection of appropriate ceramic materials. This part is dedicated to the fabrication and incorporation of extensive restorations.
Subject(s)
Humans , Female , Ceramics , Crowns , Dental Veneers , Esthetics, Dental , InlaysABSTRACT
A infinidade de materiais e as etapas de tratamento necessárias poderão ser sincronizadas e eficientes, no sentido de um desfecho de sucesso, somente se os objetivos do tratamento forem definidos antes de seu início. Neste artigo de duas partes, os autores apresentam um modo sistemático para a confecção de reabilitações orais em casos complexos. A primeira parte do artigo trata do eficiente planejamento e da seleção de materiais cerâmicos apropriados...
Only if the treatment goals have been well defined before the treatment is started may the range of materials and the required treatment steps be synchronized with each other and streamlined towards a successful outcome. In this two-part article Prof. Dr Daniel Edelhoff and Oliver Brix present a systematic way to the full-mouth rehabilitation of complex cases. The first part deals with the efficient planning and targeted selection of appropriate ceramic materials...