ABSTRACT
An extremely high degree of circularly polarized photoluminescence (CPPL) and electroluminescence (CPEL) (dissymmetry factor values: |gPL | = 0.72 and |gEL | = 1.13) are generated from twisted stacking of achiral conjugated polymer induced by nonemitting chiral dopant of high helical twisting power for the first time. Using a theoretical analysis incorporating the Stokes parameter, the twisting angle and birefringence of the aligned conjugated polymer, and the degree of linear polarization in the emitted light are found to make a roughly equal contribution to the degree of CPEL as to the degree of CPPL. Moreover, it is also found that the location of the recombination zone within the emitting layer is a crucial parameter for determining the difference in the dissymmetry factor between CPEL and CPPL. This result is applied to an organic light-emitting display to improve the luminous efficiency by 60%.
ABSTRACT
PURPOSE: To determine the optimal dilation pixel size distance from the mini-implant interface needed to compensate for the metal artifact on micro-computed tomography (micro-CT) for bone morphometric analysis. MATERIALS AND METHODS: A total of 72 self-drilling mini-implants were placed into the buccal alveolar bone of six male beagle dogs. After 12 weeks of orthodontic loading, specimens were harvested and scanned with micro-CT (Skyscan 1076) at a resolution of 9 µm. Using the reload plug-in and dilation procedure of CTAn, the percentage of bone-implant contact (BIC) and bone volume density (BV/TV, bone volume/total volume), respectively, were measured from one to seven pixels from the metal implant surface. Each pixel size of dilation (PSD) were compared with that of a ground histologic section, and the optimal PSD for bone morphometric analysis using micro-CT was determined. RESULTS: BIC values from micro-CT analysis decreased when the PSD increased (P < .05). BIC from micro-CT showed the highest correlation coefficient with BIC from histologic slides when the PSD was 5 to 7 (P < .05), whereas BV/TV from micro-CT showed a very high correlation with BV/TV from histologic slides in all ranges (P < .0001). CONCLUSION: To measure BIC and BV/TV using micro-CT, at least 5 PSD from the metal implant surface is needed.
Subject(s)
Alveolar Process/diagnostic imaging , Artifacts , Bone Density , Dental Implantation, Endosseous/methods , Dental Implants , Osseointegration , Alveolar Process/pathology , Animals , Dental Implant-Abutment Design , Dental Restoration Failure , Dilatation/methods , Dogs , Male , X-Ray Microtomography/methodsABSTRACT
PURPOSE: The recent use of microcomputed tomography (microCT) has made it possible to analyze qualitative bone morphology at the implant surface and in the peri-implant region. The purpose of this study was to evaluate histomorphometric changes around the implant-bone interface after placement of mini-implants using three-dimensional microCT analysis and to compare the stability of the implants after immediate and early loads were applied. MATERIALS AND METHODS: Forty-eight orthodontic mini-implants (ORLUS, Ortholution) were placed in the mandibular buccal jawbone of eight beagle dogs. Force was applied immediately (immediate loading group) and 3 weeks (early loading group) after implant placement; control implants received no loading. An orthodontic force (250 to 300 g) was applied to the experimental implants for 3, 6, or 12 weeks before sacrifice. RESULTS: The bone-implant contact in both experimental groups was not significantly different for any loading period except for after 12 weeks of loading. The immediate loading group had higher bone volume percentages compared with the early loading group after 6 weeks, but there was no significant difference between groups after 12 weeks. This was in accordance with the results of the three-dimensional microCT analysis. CONCLUSION: Histologic and microCT analysis showed that immediate loading of mini-implants in the dog model is possible for orthodontic applications with a high bone-implant contact and 100% survival rate.
