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Ju-Won Eom Young-Jun Lim Myung-Joo Kim Ho-Beom Kwon 《The Journal of prosthetic dentistry》2017,117(6):735-742
Statement of problem
Whether the implant abutment in implant-assisted removable partial dentures (IARPDs) functions as a natural removable partial denture (RPD) tooth abutment is unknown.Purpose
The purpose of this 3-dimensional finite element study was to analyze the biomechanical behavior of implant crown, bone, RPD, and IARPD.Material and methods
Finite element models of the partial maxilla, teeth, and prostheses were generated on the basis of a patient’s computed tomographic data. The teeth, surveyed crowns, and RPDs were created in the model. With the generated components, four 3-dimensional finite element models of the partial maxilla were constructed: tooth-supported RPD (TB), implant-supported RPD (IB), tooth-tissue-supported RPD (TT), and implant-tissue-supported RPD (IT) models. Oblique loading of 300 N was applied on the crowns and denture teeth. The von Mises stress and displacement of the denture abutment tooth and implant system were identified.Results
The highest von Mises stress values of both IARPDs occurred on the implants, while those of both natural tooth RPDs occurred on the frameworks of the RPDs. The highest von Mises stress of model IT was about twice that of model IB, while the value of model TT was similar to that of model TB. The maximum displacement was greater in models TB and TT than in models IB and IT. Among the 4 models, the highest maximum displacement value was observed in the model TT and the lowest value was in the model IB.Conclusions
Finite element analysis revealed that the stress distribution pattern of the IARPDs was different from that of the natural tooth RPDs and the stress distribution of implant-supported RPD was different from that of implant-tissue-supported RPD. When implants are used for RPD abutments, more consideration concerning the RPD design and the number or location of the implant is necessary. 相似文献6.
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Statement of problem
Research of the ability of a cast mounted on an articulator on maintaining the identical position of a cast mounted on an articulator after repeated repositioning is lacking, despite the possible effects this may have on the occlusion of a mounted cast.Purpose
The purpose of this in vitro study was to verify and compare the vertical repositioning accuracy of 4 different, commercially available articulator magnetic mounting plate systems.Material and methods
Four articulators and their associated magnetic mounting plates were selected for the study. These were the Artex AR articulator (Amann Girrbach AG), the Denar Mark II articulator (Whip Mix Corp), the Kavo Protar Evo articulator (Kavo Dental GmbH), and the SAM3 articulator (SAM Präzisionstechnik GmbH). Three new magnetic mounting plates were prepared for each articulator system. The repositioning accuracy of each mounting plate was evaluated by comparing the standard deviation of the vertical distances measured between the mounting plate and a laser displacement sensor. The lower arm of the articulator was secured, and the vertical distance was measured by positioning the laser displacement sensor positioned vertically above the mounting plate. Once the vertical distance was measured, the mounting plate was detached from the articulator and reattached manually to prepare for the next measurement. This procedure was repeated 30 times for each of the 3 magnetic mounting plates. Data were analyzed by ANOVA for 2-stage nested design and the Levene test (α=.05).Results
Significant differences were detected among articulator systems and between magnetic mounting plates of the same type. The standard deviations of the measurements made with the Artex AR articulator, Denar Mark II articulator, Kavo Protar Evo articulator, and SAM3 articulator were 0.0027, 0.0308, 0.0214, and 0.0215 mm, respectively. Thus, the repositioning accuracy could be ranked in the order as follows: Artex AR, Kavo Protar Evo, SAM3, and Denar Mark II.Conclusions
The position of the magnetic mounting plate after repositioning did not maintain an identical position in the vertical dimension on any of the 4 articulator models tested. The repositioning accuracy of the mounting plates showed significant differences among the articulators tested in this study. 相似文献13.
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Hong-Keun Hyun Soojung Kim Changmin Lee Teo Jeon Shin Young-Jae Kim 《The Journal of prosthetic dentistry》2017,117(2):294-302
Statement of problem
Few studies have investigated the colorimetric distribution of gingival color, including the posterior area and alveolar mucosa.Purpose
The purpose of this in vivo study was to investigate the distribution of colorimetric values in different areas of gingiva and to determine its relationship to colorimetric findings of the tooth and skin in a young Korean population.Material and methods
Participants included 40 periodontally healthy adults (22 men and 18 women) 25 to 36 years of age. Commission Internationale de l'Eclairage values (CIELab: L* lightness, a* green-red, and b* blue-yellow) were measured using a colorimeter at a total of 23 sites for each participant, including attached gingiva (AG) and alveolar mucosa (AM) in the maxillary and mandibular and incisor and molar regions, maxillary central incisor, and skin points of the glabella, cheek, and inner upper arm.Results
AG showed higher L* and lower a* values than AM. AG demonstrated higher L* and lower a* values in the maxillary region than in the mandibular region and higher b* values in the incisor region than in the molar region. AM revealed higher L* and lower a* and b* values in the incisor region than in the molar region. Positive significant correlations were found for L* between the skin area and AM and for b* between the skin area and AG.Conclusions
The colorimetric values of AG and AM differ according to the area, possibly as a result of differences in anatomic and histologic distribution that influence optical properties. 相似文献18.
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Comparison of two methods of profile prediction in surgical treatment of mandibular prognathism 总被引：1，自引：0，他引：1
Two methods for prediction of the soft tissue profile subsequent to oblique subcondylar osteotomy for correction of mandibular protrusion were evaluated. The first one included distalization of the mandible into an Angle Class I relationship. The amount of distalization and any vertical changes were transferred to the tracing, and the anticipated new profile was drawn. The second method was based on the profile means of a group of "normal" persons and was aimed at correction of both sagittal and vertical discrepancies. Fifty patients were studied. A double set of prediction tracings was made according to both methods; and the results were compared with the actual postoperative results and with a "normal" control group. Both methods were usable, as the predictions were considered satisfactory if they were within one standard deviation from the mean of the control group. The sagittal changes were somewhat exaggerated by both analyses. The vertical changes were much better expressed by the profile prediction. Such changes are difficult to create by the vertical subcondylar osteotomy. Consequently, the model prediction seems most suitable for planning profile changes in surgical techniques that include mobilization of one main mandibular fragment. 相似文献