Based on the theory of stance in interactive linguistics and the corpus of Bridging Cultures,this paper studies the stance-taking of advanced oral English.By using a combination of quantitative and qualitative researc...Based on the theory of stance in interactive linguistics and the corpus of Bridging Cultures,this paper studies the stance-taking of advanced oral English.By using a combination of quantitative and qualitative research to sort out and analyze the advanced oral corpus,the research finding suggests that people mainly use adjectives to express positive and negative stances,followed by nouns and verbs.Among the many grammatical constructions to express stances,“sub+is+adj”is the dominant structure,followed by“adv+adj”.It mainly presents four kinds of stance-taking in advanced oral English based on Bridging Cultures teaching materials:(1)positively evaluation stance-taking;(2)positive attitude stance-taking;(3)negative evaluation stance-taking;and(4)negative attitude stance-taking.展开更多
Background: The accuracy of the final prosthesis is affected by the final impression technique and master cast production. The aim of the present study was to evaluate the effect of the functional impression technique...Background: The accuracy of the final prosthesis is affected by the final impression technique and master cast production. The aim of the present study was to evaluate the effect of the functional impression technique with various impression materials on the surface characteristic of dental stone casts and their clinical effect on the retention of complete dentures. Method: Specimens of three impression materials/stone casts were fabricated. The specimens of the impression materials/stone casts were divided into three equal groups (I, II, and III). The impression materials used were as follows: tissue conditioner group (I), zinc oxide (ZEO) (group II) and poly (vinyl siloxane) (PVS) (group III). Cylindrical split aluminium moulds were designed to receive the impression materials and the stone mixture. The surface roughness of the stone cast specimens of the three groups (I, II, and III) was measured with a surface profilometer and analyzed by a scanning electron microscope. A clinical study included five severely resorbed mandibular edentulous alveolar ridges and edentulous maxillary arches. Each subject received three heat-cured acrylic resin dentures, fabricated using the functional impression technique. The three dentures were identical except for the different impression materials used from Groups I, II and III. The retentive force of each denture for each subject was measured. Result: The results of this study revealed that the mean value of surface roughness of the stone cast surface of group I was higher than group II and group III. A statistically significant difference was observed in surface roughness and the retentive dislodging force between the three studied groups. Although using a tissue conditioner as a functional impression material led to a high level of surface roughness and good retention, it could not produce the same smooth surface quality of PVS or ZEO. These data were supported by SEM analysis. The complete dentures for these patients require important oral and denture hygiene care. Conclusion: Complete dentures made using functional impression technique with PVC as a final impression material are more comfortable, retentive and stable.展开更多
The results of a theoretical and finite element (FE) investigation of a two-material impression creep test method, using a rectangular indenter, are presented. The method uses a general formulation for steady-state cr...The results of a theoretical and finite element (FE) investigation of a two-material impression creep test method, using a rectangular indenter, are presented. The method uses a general formulation for steady-state creep deformation for multi-material components in conjunction with the results of FE analyses. The practical application of the proposed technique, in determining the secondary creep properties of heat-affected zone (HAZ) materials in welds, for which conventional creep testing methods cannot be used, is considered. A number of numerical examples are used to describe solution procedures and to verify the method.展开更多
As restorative dentists, we are faced everyday with decisions about which impression materials and techniques should be used when restoring teeth. The challenge becomes bigger when the patients present with open gingi...As restorative dentists, we are faced everyday with decisions about which impression materials and techniques should be used when restoring teeth. The challenge becomes bigger when the patients present with open gingival embrasures, the dreaded “black triangles”, which tops the list of dentist frustration while taking the impression and after preparation of veneers, crowns, bridges, etc. The technique described offers an option to avoid problems related to impressions locking in gingival embrasures and tearing on removal.展开更多
Mineral trioxide aggregate (MTA) cement is an attractive material in endodontic dentistry. The purpose of this study was to produce calcium silicate, which is a major component of MTA, from waste materials. A dental a...Mineral trioxide aggregate (MTA) cement is an attractive material in endodontic dentistry. The purpose of this study was to produce calcium silicate, which is a major component of MTA, from waste materials. A dental alginate impression gel and used chalks were selected and mixed in a suitable ratio (Code: EXP). As a control, CaCO3 and a commercial diatomite were used (Code: CON). Each powder was heated to 850。C and 1000。C, and then kneaded with water. TG-DTA, compressive tests, SEM observations, elemental mapping analyses, and XRD analyses were performed. TG-DTA indicated that weight reduction of CaCO3 started at 600。C, and it completely decomposed on heating at 850。C. The strength was affected by the temperature. After heating, CaCO3 was transformed into CaO and/or Ca2SiO4, and Ca(OH)2 was formed by mixing with water. There were no differences between EXP and CON. These data suggested that recycled wastes might be promising MTA sources.展开更多
<b>Introduction:</b> Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners...<b>Introduction:</b> Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners. Studies assessing the accuracy of digital models have shown digital models to be valid, clinically acceptable, and more quickly obtainable. With the advent of new scanners with better scanning technology researches are necessary to evaluate their accuracy and reliability. <b>Aim of Study:</b> To evaluate the diagnostic accuracy of 3D digital models obtained through intraoral and extraoral scanning modalities to the reference gold standard plaster model. <b>Material & Methods:</b> Twenty-four adult male and female subjects were randomly selected for this study. The intraoral scanners evaluated in this study were Sirona (CEREC Omnicam) and 3 shape (TRIOS 3), while the laboratory scanners used were Sirona (inEos X5), and 3 shape (D850). Intra-oral scanning of the subjects and extra-oral scanning of their alginate impressions, plaster models of the alginate impression, rubber base impression, and plaster model of their rubber base impression were done. Linear dental measurements included intermolar width, interpremolar width, intercanine width, mesiodistal width of the 1<sup>st</sup> permanent molar, 1<sup>st</sup> premolar, canine and central incisor and arch width. All data were collected, tabulated and subjected to statistical analysis. <b>Results:</b> Small differences between the plaster and digital models were observed. Intra-observer reliability analysis for 14 out of the 16 measurements showed that all variables exhibited good to excellent reliability. <b>Conclusions: </b>There was no difference between the digitization using the intraoral scanner or the laboratory scanner. The most accurate digitization technique was the 3 Shape laboratory scanner of the cast of the alginate impression. The inEos X5 showed the highest error of digitization of the alginate and rubber base impressions.展开更多
Oral diseases have emerged as one of the leading public health challenges globally.Although the existing clinical modalities for restoration of dental tissue loss and craniomaxillofacial injuries can achieve satisfact...Oral diseases have emerged as one of the leading public health challenges globally.Although the existing clinical modalities for restoration of dental tissue loss and craniomaxillofacial injuries can achieve satisfactory therapeutic results,they cannot fully restore the original complex anatomical structure and physiological function of the tissue.3D printing of biological tissues has gained growing interest in the field of oral medicine with the ability to control the bioink component and printing structure for spatially heterogeneous repairing constructs,holding enormous promise for the precise treatment of oral disease.Particularly,collagen-based materials have been recognized as promising biogenic bioinks for the regeneration of several tissues with high cell-activating and biocompatible properties.In this review,we summarize 3D printing methods for collagen-based biomaterials and their mechanisms.Additionally,we highlight the animal sources of collagen and their characteristics,as well as the methods of collagen extraction.Furthermore,this review provides an overview of the 3D bioprinting technology for the regeneration of the pulpal nerve and blood vessels,cartilage,and periodontal tissue.We envision that this technique opens up immense opportunities over the conventional ones,with high replicability and customized function,which can ultimately promote effective oral tissue regeneration.展开更多
文摘Based on the theory of stance in interactive linguistics and the corpus of Bridging Cultures,this paper studies the stance-taking of advanced oral English.By using a combination of quantitative and qualitative research to sort out and analyze the advanced oral corpus,the research finding suggests that people mainly use adjectives to express positive and negative stances,followed by nouns and verbs.Among the many grammatical constructions to express stances,“sub+is+adj”is the dominant structure,followed by“adv+adj”.It mainly presents four kinds of stance-taking in advanced oral English based on Bridging Cultures teaching materials:(1)positively evaluation stance-taking;(2)positive attitude stance-taking;(3)negative evaluation stance-taking;and(4)negative attitude stance-taking.
文摘Background: The accuracy of the final prosthesis is affected by the final impression technique and master cast production. The aim of the present study was to evaluate the effect of the functional impression technique with various impression materials on the surface characteristic of dental stone casts and their clinical effect on the retention of complete dentures. Method: Specimens of three impression materials/stone casts were fabricated. The specimens of the impression materials/stone casts were divided into three equal groups (I, II, and III). The impression materials used were as follows: tissue conditioner group (I), zinc oxide (ZEO) (group II) and poly (vinyl siloxane) (PVS) (group III). Cylindrical split aluminium moulds were designed to receive the impression materials and the stone mixture. The surface roughness of the stone cast specimens of the three groups (I, II, and III) was measured with a surface profilometer and analyzed by a scanning electron microscope. A clinical study included five severely resorbed mandibular edentulous alveolar ridges and edentulous maxillary arches. Each subject received three heat-cured acrylic resin dentures, fabricated using the functional impression technique. The three dentures were identical except for the different impression materials used from Groups I, II and III. The retentive force of each denture for each subject was measured. Result: The results of this study revealed that the mean value of surface roughness of the stone cast surface of group I was higher than group II and group III. A statistically significant difference was observed in surface roughness and the retentive dislodging force between the three studied groups. Although using a tissue conditioner as a functional impression material led to a high level of surface roughness and good retention, it could not produce the same smooth surface quality of PVS or ZEO. These data were supported by SEM analysis. The complete dentures for these patients require important oral and denture hygiene care. Conclusion: Complete dentures made using functional impression technique with PVC as a final impression material are more comfortable, retentive and stable.
基金the Engineering&Physics Science Research Council(EPSRC)the Institution of Mechanical Engineers(IMechE),UK,Ior financial support.
文摘The results of a theoretical and finite element (FE) investigation of a two-material impression creep test method, using a rectangular indenter, are presented. The method uses a general formulation for steady-state creep deformation for multi-material components in conjunction with the results of FE analyses. The practical application of the proposed technique, in determining the secondary creep properties of heat-affected zone (HAZ) materials in welds, for which conventional creep testing methods cannot be used, is considered. A number of numerical examples are used to describe solution procedures and to verify the method.
文摘As restorative dentists, we are faced everyday with decisions about which impression materials and techniques should be used when restoring teeth. The challenge becomes bigger when the patients present with open gingival embrasures, the dreaded “black triangles”, which tops the list of dentist frustration while taking the impression and after preparation of veneers, crowns, bridges, etc. The technique described offers an option to avoid problems related to impressions locking in gingival embrasures and tearing on removal.
文摘Mineral trioxide aggregate (MTA) cement is an attractive material in endodontic dentistry. The purpose of this study was to produce calcium silicate, which is a major component of MTA, from waste materials. A dental alginate impression gel and used chalks were selected and mixed in a suitable ratio (Code: EXP). As a control, CaCO3 and a commercial diatomite were used (Code: CON). Each powder was heated to 850。C and 1000。C, and then kneaded with water. TG-DTA, compressive tests, SEM observations, elemental mapping analyses, and XRD analyses were performed. TG-DTA indicated that weight reduction of CaCO3 started at 600。C, and it completely decomposed on heating at 850。C. The strength was affected by the temperature. After heating, CaCO3 was transformed into CaO and/or Ca2SiO4, and Ca(OH)2 was formed by mixing with water. There were no differences between EXP and CON. These data suggested that recycled wastes might be promising MTA sources.
文摘<b>Introduction:</b> Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners. Studies assessing the accuracy of digital models have shown digital models to be valid, clinically acceptable, and more quickly obtainable. With the advent of new scanners with better scanning technology researches are necessary to evaluate their accuracy and reliability. <b>Aim of Study:</b> To evaluate the diagnostic accuracy of 3D digital models obtained through intraoral and extraoral scanning modalities to the reference gold standard plaster model. <b>Material & Methods:</b> Twenty-four adult male and female subjects were randomly selected for this study. The intraoral scanners evaluated in this study were Sirona (CEREC Omnicam) and 3 shape (TRIOS 3), while the laboratory scanners used were Sirona (inEos X5), and 3 shape (D850). Intra-oral scanning of the subjects and extra-oral scanning of their alginate impressions, plaster models of the alginate impression, rubber base impression, and plaster model of their rubber base impression were done. Linear dental measurements included intermolar width, interpremolar width, intercanine width, mesiodistal width of the 1<sup>st</sup> permanent molar, 1<sup>st</sup> premolar, canine and central incisor and arch width. All data were collected, tabulated and subjected to statistical analysis. <b>Results:</b> Small differences between the plaster and digital models were observed. Intra-observer reliability analysis for 14 out of the 16 measurements showed that all variables exhibited good to excellent reliability. <b>Conclusions: </b>There was no difference between the digitization using the intraoral scanner or the laboratory scanner. The most accurate digitization technique was the 3 Shape laboratory scanner of the cast of the alginate impression. The inEos X5 showed the highest error of digitization of the alginate and rubber base impressions.
基金supported by the Fundamental Research Funds for the Central Universitiessupported by grants from the National Natural Science Foundation ofChina(82100961)Sichuan University postdoctoral interdisciplinary Innovation Fund.
文摘Oral diseases have emerged as one of the leading public health challenges globally.Although the existing clinical modalities for restoration of dental tissue loss and craniomaxillofacial injuries can achieve satisfactory therapeutic results,they cannot fully restore the original complex anatomical structure and physiological function of the tissue.3D printing of biological tissues has gained growing interest in the field of oral medicine with the ability to control the bioink component and printing structure for spatially heterogeneous repairing constructs,holding enormous promise for the precise treatment of oral disease.Particularly,collagen-based materials have been recognized as promising biogenic bioinks for the regeneration of several tissues with high cell-activating and biocompatible properties.In this review,we summarize 3D printing methods for collagen-based biomaterials and their mechanisms.Additionally,we highlight the animal sources of collagen and their characteristics,as well as the methods of collagen extraction.Furthermore,this review provides an overview of the 3D bioprinting technology for the regeneration of the pulpal nerve and blood vessels,cartilage,and periodontal tissue.We envision that this technique opens up immense opportunities over the conventional ones,with high replicability and customized function,which can ultimately promote effective oral tissue regeneration.
