Zugl.: Bremen, Univ., Diss., 2007

Thesis (M.S. in computer engineering)--Washington State University, December 2005. / Includes bibliographical references (p. 60-61).

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 91-94).

Dissertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: axiomatic design, case-based reasoning, fixture design, retrieval-by-adaptabilty. Includes bibliographical references (p.273-281).

Thesis (M. S.)--Architecture, Georgia Institute of Technology, 2007. / Athanassios Economou, Committee Member ; Chuck Eastman, Committee Member ; Russell Gentry, Committee Chair.

Universiẗat, Diss., 2002--Kassel. / Lizenzpflichtig.

OBJECTIVES: To test and compare the effects of static and cyclic loading on fracture toughness (K1C) and microhardness of dental restorative CAD/CAM materials. MATERIAL AND METHODS: Five commercially available CAD/CAM restorative materials were included in this study: Lava™ Ultimate Restorative (3M ESPE), IPS Empress® CAD (Ivoclar Vivadent), Enamic® (VITA), IPS e.max® CAD (Ivoclar Vivadent), and CERASMART™ (GC Dental). Polished rectangular bars 4×2×14 mm (n=30) were prepared from mill blocks for each material. Single notch of 0.5-1 mm in depth was made on the center of one length edge. Ten specimens per group for each material were randomly selected for 1) static mode, 2) after 100k cyclic loads, and 3) after 200k cyclic loads. The survival bars after the fatigue test were then subjected to a three-point flexural test. K1C values were determined on ‘single-edge-pre-crack-beams’ (SEPB) method. In addition, random specimens after the flexural test were selected for Vickers microhardness test from each group. Additionally indentation fracture method (IF) was used to determine surface fracture toughness for e.max CAD and Empress CAD. All the results were analyzed via ANOVA with Tukey’s HSD test or least square regression model using JMP Pro 12.0. RESULTS: The mean fracture toughness (K1C) of the material tested in static mode (3.2 MPa.m1/2 for e.max CAD, 2 MPa.m1/2 for Lava Ult, 1.95 MPa.m1/2 for Empress CAD, 1.92 MPa.m1/2 for Enamic, and 1.65 MPa.m1/2 for Cerasmart). The 100k fatigue group (4.02 MPa.m1/2 for e.max CAD, 3.06 MPa.m1/2 for Cerasmart, 2.55 MPa.m1/2 for Lava Ult, 2.01 MPa.m1/2 for Enamic, 1.94 MPa.m1/2 for Empress CAD) The 200k fatigue group (3.14 MPa.m1/2 for Cerasmart, 2.83 MPa.m1/2 for Lava Ult, 2.68 MPa.m1/2 for e.max CAD, 2.01 MPa.m1/2 for Enamic, 1.72 MPa.m1/2 for Empress CAD). While there was a significant difference in the mean fracture toughness (K1C) and (VHN) after fatigue of material tested (p<0.05). CONCLUSION: The CAD/CAM materials tested exhibited a higher K1C values after cyclic loading, along with lower K1C compared to the static group. In addition, K1C values by IF method exhibit lower K1C values after fatigue that was not a good way to test the fracture toughness value. / 2018-09-28T00:00:00Z

OBJECTIVE: To explore a novel virtual inspection approach with a 3D metrology software to provide a non-destructive in situ analysis in digital workflow. Also, to evaluate the fit discrepancies of lithium disilicate crowns by using such a novel virtual measuring technique. MATERIALS AND METHODS: Maxillary arch typodont was used to design abutment for tooth #8 and #14 (hand prepared) and #4 and #10 (titanium custom abutment). All four abutments were placed into a duplicated maxillary arch solid stone model for scanning with laboratory scanner. Four crown patterns were designed and exported as STL files. The internal control group consists of the four original digital STL files and the external control group which was the 32-milled lithium disilicate crowns (IPS e.max® CAD, Ivoclar Vivadent, Inc.), eight patterns for each tooth. Thirty-two pressable wax patterns (8 of each) was fabricated for each of the three different technique systems. Two printed wax systems, Varseo Wax CAD/Cast (BEGO) and Press-E-Cast (EnvisionTec). Two milled wax systems Harvest Wax (Ivoclar Vivadent, Inc.) and Polycon Cast (Straumann), and a set of conventional cutbacks of 1.5mm with applied marginal wax. All patterns were pressed into lithium disilicate crowns, then fine polished and scanned. Each file was imported into a quality control metrology software (Geomagic Control X, 3D Systems) for marginal fit and internal fit evaluation with respective digital abutment. RESULTS: Mean of marginal gap for all groups were all lower than the preset gap space of 40 microns. Statistically significant differences in the fit accuracy were found among tooth number, technique system and measurement locations, but the differences are in clinically acceptable range. New scope of analyzing a restoration in a 3D fashion can help solve clinical complications. The study has shown that lower marginal gap does not necessary indicates a better fit restoration, as every level of the crown should be evaluated for. CONCLUSION: This novel inspection method can be used as a replacement of fit checker and help clinician to work in a full digital workflow. Lithium disilicate restorations fabricated through printed wax pattern, milled wax pattern and conventional hand wax are all clinically acceptable techniques. / 2019-09-26T00:00:00Z

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em Odontologia. / Made available in DSpace on 2012-10-25T17:31:02Z (GMT). No. of bitstreams: 1 301845.pdf: 115870214 bytes, checksum: aa98afe9cd6864bfc8b60a93d03adfcf (MD5) / O objetivo deste estudo in vitro foi comparar a precisão de moldagem da técnica digital com a precisão de moldagem da técnica convencional por meio da análise da adaptação marginal e interna de estruturas de próteses fixas (PFs) de zircônia de quatro elementos geradas por CAD/CAM. Materiais e Método: um modelo-mestre de titânio foi utilizado para a fabricação das estruturas de zircônia que foram divididas em dois grupos experimentais: MD (Moldagem Digital) e MC (Moldagem Convencional). Para o grupo MC, doze moldagens do modelo-mestre foram feitas com poliéter (Impregum, 3M ESPE) com o auxílio de moldeiras individuais; em seguida, os moldes foram vazados com gesso pedra Classe IV (Fujirock,GC), e troquelizados. Os doze troquéis foram escaneados pelo sistema de escaneamento óptico LavaTM Scan ST. Para o grupo MD, doze moldagens digitais do modelo-mestre foram realizadas com o sistema LavaTM C.O.S. As estruturas de zircônia de ambos os grupos foram usinadas a partir de blocos de zircônia semissinterizados. No intuito de confeccionar os espécimes relativos às fendas marginais e ao espaço interno de cimentação dos retentores das PFs, a técnica da réplica foi utilizada de modo que, para cada dente-pilar, fossem obtidas duas secções transversais (vestíbulo-lingual e mésio-distal). Fotografias dos espécimes foram tiradas com uma câmera acoplada a um microscópio óptico. As imagens microscópicas foram exportadas para um software de análise de imagens (Optimas 6.5), onde as mensurações da adaptações marginais e internas foram conduzidas. As médias dos valores foram analisadas por meio do teste estatístico Mann-Whitney-U. Resultados para a adaptação geral: O grupo MD (59,84 ?m) mostrou valor médio significantemente inferior ao grupo MC (67,79 ?m) P=0,01. Os grupos MD e MC demonstraram adaptação marginal com valores médios sem diferença estatística de 63,96 ?m e 65,33 ?m, respectivamente. Os grupos MD e MC apresentaram valores de adaptação interna significantemente diferentes de 58,46 ?m e 65,94 ?m, P=0,007, respectivamente. Conclusões: As PFs confeccionadas por meio de ambas as moldagens digital e convencional exibiram valores de adaptação marginal clinicamente aceitáveis. A moldagem digital gerou melhores valores de adaptações geral e interna do que a moldagem convencional. Considerando cada face dos dentes-pilares, um padrão heterogêneo de distribuição nos valores foi observado para as adaptações marginal e interna. / The aim of this in vitro study was to assess the precision of fit of CAD/CAM-generated four-unit zirconia fixed dental prostheses (FDPs) made through digital and conventional impressions. Material and method: a titanium master model was used as a basis for manufacturing the zirconia frameworks which were divided into two groups DI (Digital Impression) and CI (Conventional Impression). For group CI, twelve polyether impressions Impregum (3M ESPE) of the master model were made with aid of custom trays and poured in a Class IV stone (Fujirock). The twelve pin-models were scanned by an optical scanning device (LavaTM Scan ST). As for group DI, twelve digital impressions of the master model using LavaTM C.O.S. system were made. The frameworks of both groups were milled from semi-sintered zirconia. In order to obtain replicas of the marginal and internal gaps of the FDPs retainers, the replica technique was applied so that, per retainer, two cross-sectional specimens (buccal-palatal and mesio-distal) were obtained. Photographs of the specimens were taken with a digital camera which was attached to a microscope. The microscopic images were transferred to the imaging data software (Optimas 6.5), wherein the measurements of marginal and internal fit were carried out. Mean values were analyzed with descriptive statistics. Mann-Whitney-U statistical test was used to detect statistical differences between both investigated type of impressions in terms of marginal and internal fit for overall values and for values of different abutments faces. Results for overall fit: Group DI (59.84 ìm) showed significant lower mean value than group CI (67.79 ìm) P=0.01. Group DI and CI presented marginal fit of 63.96 ìm and 65.33 ìm, respectively, which showed no statistical difference. Groups DI and CI presented internal fit of 58.46 ìm and 65.94 ìm, respectively, which were statistically different, P=0.007. Conclusions: Both digital and conventional impressions tested showed clinically acceptable marginal fit. Digital impression demonstrated better overall and internal fit than conventional impression. Considering each abutment face, a heterogeneous distribution pattern was shown for internal and marginal fit.

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnologico / Made available in DSpace on 2016-01-08T19:01:36Z (GMT). No. of bitstreams: 1 95779.pdf: 6701331 bytes, checksum: 4fd2472a705d6f86af6e139d8078b1d0 (MD5) Previous issue date: 1994 / Neste trabalho é feita uma abordagem sobre o estado-da-arte com relação à utilização de sistemas CAE/CAD/CAM no setor de moldes de injeção para peças de plástico. Através da elaboração de um Manual de Orientação sobre o assunto, são apresentados conceitos básicos, referentes a tecnologia CAx, detalhando as fases do processo de desenvolvimento de um molde onde já é possível obter o auxílio destas tecnologias. Além disso, são apresentadas considerações visando orientar a implantação de sistemas CAx, bem como é feita uma abordagem sobre problemas e dificuldades inerentes ao emprego de sistemas CAE/CAD/CAM em empresas de moldes de injeção, baseada na análise de estudos de casos, análise de artigos especializados e projetos da comunidade européia, bem como relatos de experiências industriais. Concluindo, são apresentadas as características básicas que devem estar presentes em um sistema CAx tipicamente voltado ao referido setor.