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You searched for +publisher:"University of Hong Kong" +contributor:("Leung, KCM"). Showing records 1 – 2 of 2 total matches.

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University of Hong Kong

1. Said, Mohamed Moustafa Mohamed Ali. Characterization of titanium surfaces with different treatment and aging processes.

Degree: M. Phil., 2012, University of Hong Kong

The aims of this study were to, 1) investigate the surface characteristics of polished titanium plates/discs treated with acid-etching and ultraviolet irradiation (UV); and 2) investigate the change in surface characteristics of polished titanium plates/discs treated with acid-etching and UV irradiation after aging in air, saline and citric acid for six weeks. A total of one hundred and ninety-eight commercially pure grade two titanium plates and 50 titanium discs were prepared. Titanium samples were divided into four groups: 1) polished group, 2) polished and UV group, 3) acid-etched group and 4) acid-etched and UV group. Polishing was performed by abrasive silicon carbide paper grinding. UV treatment was performed by 15W germicidal UVC, 254 nm, for 48 h. Acid-etching was performed with 67% H2SO4 at 120 ºC for 75 s. The four groups were then subjected to an aging process for six weeks in sealed containers with three different media: air, physiologic saline and citric acid. They were analyzed immediately after treatment and after aging for surface characterization: topography, roughness, wettability, crystallinity, and chemistry. The polished surface showed relatively smooth surface with typical grooves from the grinding process. Acid-etching produced micro-roughened surface with sharp pits and ridges. The average surface roughness of polished, polished-UV was lower than that of the acid-etched and acid-etched-UV surfaces (p < 0.05). Storage of titanium in saline and citric acid did not provoke any morphological or roughness changes at micron scale level when compared to the samples stored in air. Immediately after preparation and treatment, the polished and acid-etched titanium surfaces appeared to be hydrophilic with similar contact angle values (p > 0.05). After UV treatment, there was a significant reduction in contact angles (superhydrophilic) in both surfaces (p < 0.05). After storage in air for six weeks, the contact angles of the four groups significantly increased (p < 0.05) and the surfaces converted to a hydrophobic state. In contrast to samples stored in air, samples stored in saline and citric acid revealed superhydrophilic surfaces regardless of the surface type. Titanium hydride crystals were present in the acid-etched and acid-etched-UV surfaces but not in the polished and polished-UV surfaces. Titanium tetrachloride crystals were present in saline-stored surfaces. The polished surface acquired significantly higher titanium and oxygen concentrations and lower carbon contaminants compared to acid-etched surface. UV treatment substantially decreased carbon contamination and increased the titanium and oxygen concentrations in the acid-etched groups (p < 0.05). After storage for six weeks in air, the four studied surfaces had no significant changes in the surface chemistry. Storage of the titanium samples in saline and citric acid relatively increased the carbon contamination and decreased titanium and oxygen concentrations. UV treatment may be an effective way to produce clean titanium surfaces… Advisors/Committee Members: Matinlinna, JP, Leung, KCM.

Subjects/Keywords: Dental implants.; Titanium.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Said, M. M. M. A. (2012). Characterization of titanium surfaces with different treatment and aging processes. (Masters Thesis). University of Hong Kong. Retrieved from Said, M. M. M. A.. (2012). Characterization of titanium surfaces with different treatment and aging processes. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4979968 ; http://dx.doi.org/10.5353/th_b4979968 ; http://hdl.handle.net/10722/181534

Chicago Manual of Style (16th Edition):

Said, Mohamed Moustafa Mohamed Ali. “Characterization of titanium surfaces with different treatment and aging processes.” 2012. Masters Thesis, University of Hong Kong. Accessed March 20, 2019. Said, M. M. M. A.. (2012). Characterization of titanium surfaces with different treatment and aging processes. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4979968 ; http://dx.doi.org/10.5353/th_b4979968 ; http://hdl.handle.net/10722/181534.

MLA Handbook (7th Edition):

Said, Mohamed Moustafa Mohamed Ali. “Characterization of titanium surfaces with different treatment and aging processes.” 2012. Web. 20 Mar 2019.

Vancouver:

Said MMMA. Characterization of titanium surfaces with different treatment and aging processes. [Internet] [Masters thesis]. University of Hong Kong; 2012. [cited 2019 Mar 20]. Available from: Said, M. M. M. A.. (2012). Characterization of titanium surfaces with different treatment and aging processes. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4979968 ; http://dx.doi.org/10.5353/th_b4979968 ; http://hdl.handle.net/10722/181534.

Council of Science Editors:

Said MMMA. Characterization of titanium surfaces with different treatment and aging processes. [Masters Thesis]. University of Hong Kong; 2012. Available from: Said, M. M. M. A.. (2012). Characterization of titanium surfaces with different treatment and aging processes. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4979968 ; http://dx.doi.org/10.5353/th_b4979968 ; http://hdl.handle.net/10722/181534


University of Hong Kong

2. Xin, Weini. A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients.

Degree: PhD, 2012, University of Hong Kong

OBJECTIVES: The primary objective of this study was to evaluate the efficacy of fluoride varnish in caries prevention and arrest on coronal and root surfaces of teeth over a 24-month period in Chinese Sjögren’s syndrome (SS) patients. Secondary objective was to investigate the effect of fluoride varnish on oral microorganism (Candida and lactobacilli). METHODS: This study was a randomized, double-blind, placebo-controlled clinical trial. A total of 85 SS patients participated in this study. They were randomly assigned to two groups to receive either fluoride varnish or placebo gel quarterly. Dental examination, and assessment of the sicca symptoms, oral hygiene, salivary flow / pH / buffering capacity and oral microbiological profiles were carried out at the baseline, 12-month and 24-month visits. RESULTS: Seventy-eight patients (92%) completed the 24-month trial. At the 24-month visit, no statistically significant differences (Mann-Whitney test, P > 0.05) were found between the fluoride and the placebo groups regarding their mean numbers of coronal surfaces with new enamel caries lesions (fluoride: 1.6; placebo: 1.6), arrested caries lesions (fluoride: 0.6; placebo: 0.7), and also root surface caries lesions (fluoride: 0.3; placebo: 0.1). SS patients who had received application of fluoride varnish were significantly less likely to develop dentin caries in coronal surfaces over the 24-month study period (P = 0.035). The mean numbers of coronal surfaces with new dentin caries lesions found at the 24-month visit in the fluoride and placebo groups were 1.4 and 2.7, respectively (Mann-Whitney test, P > 0.05). The caries prevented fraction of fluoride varnish for coronal dentin caries was 33.3%. No significant differences in the mean counts of Candida and lactobacilli between fluoride and placebo groups were detected (Mann-Whitney test, P > 0.05). Results of the logistic regression analysis showed that SS patients who had high baseline DMFS scores (P = 0.050), harbored more species of Candida in the dental plaque samples (P = 0.019), or had low pH of unstimulated whole saliva (P = 0.005) were significantly more likely to develop dentin caries in coronal surfaces over the 24-month study period. CONCLUSIONS: Fluoride varnish may be efficacious in preventing coronal dentin caries in Chinese patients with SS. However, it may not be efficacious in preventing root caries and has no effect on oral microorganism.

published_or_final_version

Dentistry

Doctoral

Doctor of Philosophy

Advisors/Committee Members: Lo, ECM, Leung, KCM.

Subjects/Keywords: Dental caries - Prevention.; Sjogren's syndrome - Patients - China - Hong Kong.; Fluorides - Therapeutic use.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Xin, W. (2012). A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. (Doctoral Dissertation). University of Hong Kong. Retrieved from Xin, W. [辛蔚妮]. (2012). A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053377 ; http://dx.doi.org/10.5353/th_b5053377 ; http://hdl.handle.net/10722/188258

Chicago Manual of Style (16th Edition):

Xin, Weini. “A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients.” 2012. Doctoral Dissertation, University of Hong Kong. Accessed March 20, 2019. Xin, W. [辛蔚妮]. (2012). A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053377 ; http://dx.doi.org/10.5353/th_b5053377 ; http://hdl.handle.net/10722/188258.

MLA Handbook (7th Edition):

Xin, Weini. “A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients.” 2012. Web. 20 Mar 2019.

Vancouver:

Xin W. A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. [Internet] [Doctoral dissertation]. University of Hong Kong; 2012. [cited 2019 Mar 20]. Available from: Xin, W. [辛蔚妮]. (2012). A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053377 ; http://dx.doi.org/10.5353/th_b5053377 ; http://hdl.handle.net/10722/188258.

Council of Science Editors:

Xin W. A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. [Doctoral Dissertation]. University of Hong Kong; 2012. Available from: Xin, W. [辛蔚妮]. (2012). A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren's syndrome patients. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053377 ; http://dx.doi.org/10.5353/th_b5053377 ; http://hdl.handle.net/10722/188258

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