Biomedical subjects

Xiaojie Zhou

Publications and source records attributed to Xiaojie Zhou.

12 recordsLinked to original sources

PubMed2006

Long-term risedronate treatment normalizes mineralization and continues to preserve trabecular architecture: sequential triple biopsy studies with micro-computed tomography.

The objective of the study was to assess the time course of changes in bone mineralization and architecture using sequential triple biopsies from women with postmenopausal osteoporosis (PMO) who received long-term treatment with risedronate. Transiliac biopsies were obtained from the same subjects (n = 7) at baseline and after 3 and 5 years of treatment with 5 mg daily risedronate. Mineralization was measured using 3-dimensional (3D) micro-computed tomography (CT) with synchrotron radiation and was compared to levels in healthy premenopausal women (n = 12). Compared to the untreated PMO women at baseline, the premenopausal women had higher average mineralization (Avg-MIN) and peak mineralization (Peak-MIN) by 5.8% (P = 0.003) and 8.0% (P = 0.003), respectively, and lower ratio of low to high-mineralized bone volume (BMR-V) and surface area (BMR-S) by 73.3% (P = 0.005) and 61.7% (P = 0.003), respectively. Relative to baseline, 3 years of risedronate treatment significantly increased Avg-MIN (4.9 +/- 1.1%, P = 0.016) and Peak-MIN (6.2 +/- 1.5%, P = 0.016), and significantly decreased BMR-V (-68.4 +/- 7.3%, P = 0.016) and BMR-S (-50.2 +/- 5.7%, P = 0.016) in the PMO women. The changes were maintained at the same level when treatment was continued up to 5 years. These results are consistent with the significant reduction of turnover observed after 3 years of treatment and which was similarly maintained through 5 years of treatment. Risedronate restored the degree of mineralization and the ratios of low- to high-mineralized bone to premenopausal levels after 3 years of treatment, suggesting that treatment reduced bone turnover in PMO women to healthy premenopausal levels. Conventional micro-CT analysis further demonstrated that bone volume (BV/TV) and trabecular architecture did not change from baseline up to 5 years of treatment, suggesting that risedronate provided long-term preservation of trabecular architecture in the PMO women. Overall, risedronate provided sustained benefits on mineralization and architecture, two key determinants of bone strength, over 5 years lending support for its long-term efficacy in fracture risk reduction.

Adult↗

PubMed2005

Multi-model direct adaptive decoupling control with application to the wind tunnel system.

In this paper, a new multi-model direct adaptive decoupling controller is presented for multivariable processes, which includes multiple fixed optimal controllers, one free-running adaptive controller, and one re-initialized adaptive controller. The fixed controllers provide initial control to the process if its model lies in the corresponding region. For each controller selected, the re-initialized adaptive controller uses the values of this particular controller to improve the adaptation speed. This controller may replace the fixed controller at a later stage according to the switching criterion which is to select the best one among all controllers. A free-running adaptive controller is also added to guarantee the overall system stability. Different from the multiple models adaptive control structure proposed in Narendra, Balakrishnan, and Ciliz [Adaptation and learning using multiple models, switching, and tuning. IEEE Control Syst. Mag. 15, 37-51 (1995)], the method not only is applicable to the multi-input multi-output processes but also identifies the decoupling controller parameters directly, which reduces both the computational burden and the chances of a singular matrix during the process of determining controller parameters. Several examples for a wind tunnel process are given to demonstrate the effectiveness and practicality of the proposed method.

Journal Article↗

PubMed2004

Effect of a novel integrated power toothbrush and toothpaste oral hygiene system on gingivitis.

The purpose of this article is to compare the gingivitis reduction efficacy relative to baseline of an integrated power toothbrush/toothpaste dispensing system prototype, the IntelliClean System from Sonicare and Crest. This was a randomized, controlled, parallel-group, examiner-blind study that examined the gingivitis reduction efficacy of a novel integrated system compared to a positive control consisting of manual toothbrushing coupled with daily flossing over a 4-week period. Mean change from baseline for gingival index (GI) and bleeding scores were tested using paired t tests for each treatment group, separately. Between-group comparisons were made with respect to change from baseline using analysis of covariance. Baseline values were used as the covariate. All tests were 2-sided with a 0.05 level of significance. A total of 66 subjects (61 women and 5 men) completed the study. The subjects ranged in age from 20 to 64 years with an overall mean age of 39.4 years. Baseline GI and bleeding scores were not statistically significantly different (P > .2) between the experimental integrated system group and the positive-control group. Both treatment regimen groups demonstrated highly statistically significant reductions in GI and bleeding scores vs baseline (P < .0001) at weeks 2 and 4. After 4 weeks, there was a 28% mean reduction in GI for the experimental group and a 23% mean reduction for the positive-control group. Similarly, there was a 28% mean reduction in bleeding for the experimental integrated system group and a 23% reduction for the positive-control group. However, no statistically significant treatment difference was found between the 2 groups (P > .5) for either measure at week 2 or week 4. This study demonstrated the efficacy of the IntelliClean System from Sonicare and Crest in significantly reducing gingivitis and bleeding relative to baseline after 4 weeks of use according to the manufacturer's instructions.

Adult↗

PubMed2004

Pharmacodynamic and pharmacokinetic effects in gingival crevicular fluid from re-dosing during brushing.

The IntelliClean System from Sonicare and Crest combines a rechargeable sonic power toothbrush and a novel liquid toothpaste into one integrated system, providing the opportunity to re-dose with toothpaste during the brushing cycle. The purpose of this study was to investigate cleaning effects from in-mouth re-dosing with toothpaste during the brushing cycle vs conventional bolus dosing. This was a randomized, examiner-blind, six-period, crossover clinical study. Eighteen adult subjects used an experimental integrated system employing either a re-dosing regimen (2 doses at the start of brushing with 1 additional in-mouth dose during the last 30 seconds of brushing [2+1]) or a conventional regimen (2 doses at the start of brushing only [2+0]). Gingival crevicular fluid (GCF) was sampled at the final brushing quadrant from a preselected site in the gingival sulcus using filter strips at baseline and at 4, 15, and 120 minutes postbrushing. Mean change from baseline in the concentrations of total facultative anaerobes (TFAs) and gram-negative anaerobes (GNAs) in the GCF at 120 minutes posttreatment were modeled separately using general linear mixed models. Area under the curve of surfactant (sodium dodecyl sulfate [SDS]) in GCF over 2 hours postbrushing was calculated and modeled using an analysis of variance model. All hypotheses were tested 2-sided at the 5% significance level. Relative to the conventional regimen, the re-dosing (2+1) regimen produced a significantly greater reduction in log10 (TFA colony-forming units [CFU]/microL GCF) after brushing, 0.99+/-0.12 vs 0.65+/-0.12 (mean change +/- standard error), and a significantly greater reduction in log10 (GNA CFU/microL GCF) after brushing, 0.75 +/-0.14 vs 0.45 +/- 0.14. The re-dosing regimen led to significantly more SDS in GCF relative to the conventional regimen over the 2-hour time period. Re-dosing of liquid toothpaste during the brushing cycle with the IntelliClean System leads to a significantly increased cleaning effect, as defined by a reduced bacterial count in GCF, and significantly higher levels of surfactant in the GCF up to 2 hours after the brushing event.

Adult↗

PubMed2004

Clinical trial comparing two daytime hydrogen-peroxide professional vital-bleaching systems.

A randomized clinical trial was conducted to compare the whitening effectiveness and tolerability of two daytime, professional, hydrogen-peroxide, vital-bleaching systems. Adults who had never bleached their teeth were randomly assigned to use either 14% hydrogen-peroxide whitening strips or a marketed 9.5% hydrogen-peroxide custom-tray-based system. Maxillary arch treatment was twice daily for 30 minutes for 9 to 21 days, depending on the labeled instructions for use. Whitening response was measured objectively as L*a*b* (which represent three-dimensional tooth color from light to dark, green to red, and blue to yellow, respectively) from digital images of the maxillary anterior teeth, while comparative at-home tolerability was assessed from bleaching tolerability severity days (BTSD) scores. A total of 31 participants aged 18 to 64 were evaluated. At the end of treatment, the adjusted mean (standard deviation [SD]) delta b* was -3.35 (0.37) for the strips and -1.67 (0.344) for the trays. Treatments differed significantly (P < .05) with respect to delta b*, as well as to delta L* and delta W* values at the end of treatment. Overall, at-home strip use was better tolerated, especially with respect to oral irritation. BTSD means (SD) were 0.09 (0.25) and 0.38 (0.49), with treatments differing significantly (P = .036), favoring the strips. This comparative research demonstrated that at the end of treatment, the 14% hydrogen-peroxide whitening strips resulted in a superior, twofold reduction in yellowness and better in-use tolerability compared to the 9.5% hydrogen-peroxide custom-tray system.

Adult↗

PubMed2003

A Bayesian A-optimal and model robust design criterion.

Suppose that the true model underlying a set of data is one of a finite set of candidate models, and that parameter estimation for this model is of primary interest. With this goal, optimal design must depend on a loss function across all possible models. A common method that accounts for model uncertainty is to average the loss over all models; this is the basis of what is known as Läuter's criterion. We generalize Läuter's criterion and show that it can be placed in a Bayesian decision theoretic framework, by extending the definition of Bayesian A-optimality. We use this generalized A-optimality to find optimal design points in an environmental safety setting. In estimating the smallest detectable trace limit in a water contamination problem, we obtain optimal designs that are quite different from those suggested by standard A-optimality.

Bayes Theorem↗

PubMed2002

Effect of peroxide concentration and brushing on whitening clinical response.

This clinical trial compared the effects of hydrogen peroxide concentration and toothbrushing on clinical response to vital bleaching. Tooth bleaching was accomplished with a flexible, polyethylene strip coated with a hydrogen peroxide bleaching gel worn for 30 minutes twice daily over a 14-day period. A total of 36 subjects were randomized to 1 of 3 treatment groups: 5.3% hydrogen peroxide strip plus prebrushing, 6.5% hydrogen peroxide strip plus prebrushing, or 6.5% hydrogen peroxide strip without prebrushing. Two groups brushed with regular anticavity toothpaste immediately before bleaching, while the other group performed ad libitum brushing only. Tooth color was measured over a 14-day period using digital images of the anterior dentition. Over the 14-day treatment period, all 3 strip groups experienced highly significant (P < 0.001) whitening as evidenced by decreased yellowness (delta b*) and increased brightness (delta L*), as well as composite color change (delta E*) relative to baseline. Keeping brushing constant, the 6.5% hydrogen peroxide strip plus prebrushing group experienced a 31% to 60% improvement in whitening relative to the 5.3% hydrogen peroxide standard. Keeping concentration constant at 6.5% hydrogen peroxide, the prebrushing group experienced a directional 5% to 33% improvement in whitening relative to no prebrushing. All treatments were generally well tolerated. This study demonstrates that for strip-based delivery, increasing hydrogen peroxide concentration to 6.5% results in a significant improvement in efficacy with few tolerability trade-offs.

Adult↗

PubMed2002

Tooth whitening in children.

Although there are several case reports of vital tooth bleaching in children, there is limited clinical trial evidence of the safety or efficacy of this practice. Accordingly, a new clinical trial was conducted to evaluate the effects of 2 different bleaching systems, a 6.5% hydrogen peroxide strip system and a 10% carbamide peroxide tray system, in a population of preteens and teens. A total of 106 volunteers, aged 11 to 18 years, took part in this 8-week study. Patients were randomized by a ratio of 2:1 to the strip or tray groups, with each group treating the maxillary arch first and then the mandibular arch for 4 consecutive weeks each. Individuals assigned to the strip group used the system twice daily for 30 minutes (a total of 56 contact hours over the 8-week study). Those assigned to the tray group used that system overnight (approximately 448 contact hours). Digital images were obtained at baseline and after every 2-week treatment period. Average tooth color was determined in L*, a*, b* color space, where L* indicated lightness, a* indicated red-green, and b* indicated yellow-blue. Both systems significantly whitened teeth (P < 0.0001). While there were no significant differences between groups with respect to the primary whitening response (delta b*) on the maxillary teeth, 4 weeks of overnight treatment with the 10% carbamide peroxide tray (approximately 224 contact hours) yielded statistically significant whitening (P < 0.05) on the mandibular teeth compared with the 6.5% hydrogen peroxide strip used for 28 hours. Both tooth-whitening systems had similar sensitivity/irritation reported after instructed use. This research demonstrates that tooth whitening in teens may be safely accomplished using either the short-contact-time hydrogen peroxide bleaching strips or the overnight carbamide peroxide tray systems tested in this study.

Adolescent↗

PubMed2002

Daily use of whitening strips on tetracycline-stained teeth: comparative results after 2 months.

This article reviews the efficacy of a new 6.5% hydrogen peroxide tooth-whitening gel strip for bleaching teeth that have been intrinsically stained from tetracycline. Given the severity of staining in the cases presented during a recently conducted clinical trial, the resulting efficacy is dramatic. Additionally, the continuous use of these strips for 30 minutes per day, twice daily for 2 months with no meaningful adverse effects is noteworthy.

Adult↗

PubMed2002

Comparative clinical efficacy of two professional bleaching systems.

A randomized, parallel, examiner-blind clinical trial was conducted to compare two professionally dispensed vital bleaching systems. A total of 20 subjects were randomized to either the Crest Professional Whitestrips system or the Nite White Excel 2 tray system, balancing for baseline tooth color. During the 2-week treatment period, subjects were instructed to use the strip system for one-half hour twice daily (14 contact hours) and the tray system for 2 hours daily (28 contact hours). Only the maxillary teeth were treated, and all bleaching was unsupervised. Whitening was measured objectively by comparing digital images of the maxillary anterior dentition at pretreatment and posttreatment. Compared with baseline, both the strip and tray systems exhibited statistically significant decreases (P < 0.05) in yellowness (delta b*) and increases in brightness (delta L*). Compared with the tray-system group, the strip-system group experienced significant additional whitening (P < 0.03), as evidenced by a 62% to 209% improvement in tooth color (delta b*, delta L*, and delta E*) after 14 days. Both systems were generally well tolerated, and none of the subjects discontinued treatment early because of an adverse event. Under the conditions tested, this clinical trial demonstrates that the 14-contact-hour treatment with the strip system resulted in superior whitening efficacy compared with the 28-contact-hour treatment with the tray system.

Adult↗

PubMed2002

Vital bleaching with two at-home professional systems.

PURPOSE: To compare the whitening effectiveness of two professional vital bleaching systems in a randomized clinical trial. MATERIALS AND METHODS: Balancing for baseline color, 6 9 adult volunteers were randomized to either a whitening strip containing 6.5% hydrogen peroxide (Professional Crest Whitestrips) or a custom tray-based system using both hydrogen and carbamide peroxide (Nite White Excel2). Total contact time was 21 hours for the strip system and 28 hours for the 10% carbamide peroxide equivalent tray system. Whitening response was measured objectively as L*a*b* from digital images of the maxillary anterior teeth. RESULTS: Both treatments resulted in significant (P < 0.01) improvements in yellowness (deltab*), brightness (deltaL*) and overall color (deltaE*). For between group comparisons, strip subjects had a statistically significant or directionally favorable whitening response relative to the tray system at intermediary time points, while at the end-of-treatment, the strip group had highly statistically significant (P < or = 0.005), superior whitening response for all color parameters measured in the study. Both treatments were generally well tolerated, with 35-40% of the subjects in each group reporting minor tooth sensitivity or gingival irritation.

Adolescent↗

PubMed2002

Comparative response of whitening strips to a low peroxide and potassium nitrate bleaching gel.

PURPOSE: To evaluate the clinical response of a low peroxide concentration bleaching system with a desensitizing agent relative to a marketed control. MATERIALS AND METHODS: After balancing for baseline color and age, 34 healthy adult volunteers were randomized to one of two marketed bleaching systems, 5% carbamide peroxide bleaching gel + potassium nitrate in a custom tray (Colgate Platinum Gentle Plus) or 6.0% hydrogen peroxide bleaching strips (Crest Whitestrips). Daily contact time was 6-8 hours for the tray system compared to 1 hour for the strip system, following manufacturers' instructions. Whitening was measured objectively using digital image analysis to assess L*a*b* after 7 days, while tolerability was assessed through interview and examination. RESULTS: The predominantly female (85%) and non-smoking (91%) study population ranged from 20-47 years of age. Both treatments yielded a statistically significant (P < 0.001) whitening benefit with respect to reduction in yellowness (Ab*) and improvements in other color endpoints (deltaL*, deltaE*, and a new parameter, deltaW*) compared to baseline. The strip group experienced greater color improvement on average for all color parameters in the study. After 7 days treatment, the adjusted mean deltab* was -1.24 in the strip group and -0.65 in the tray group, with these groups differing significantly (P = 0.04). Tooth sensitivity was reported by 13% of subjects using the hydrogen peroxide strips, compared to 22% of subjects using the carbamiide peroxide potassium nitrate tray system. No subjects discontinued treatment early due to an adverse event.

Adult↗