Influence of nicotine on the biological activity of rabbit osteoblasts.

Objectives: To assess the influence of nicotine on the proliferation and gene expression of osteogenic and angiogenic mediators of osteoblasts.

Material And Methods: Rabbit primary osteoblasts were exposed to various concentrations of nicotine (0.001, 0.

3D FEA of high-performance polyethylene fiber reinforced maxillary dentures.

Objective: This project studies the effect of high-performance polyethylene (HPPE) fibers on stress distributions in a maxillary denture and the influence of fiber position on improving denture performance.

Methods: A denture was scanned with a 3D Advanced Topometric Sensor digitizing system. The measuring system converted the images into a 3D digital model.

Oral health and its impact on the life quality of homeless people in Hong Kong.

Objectives: To report on the oral health status and its impact on the life quality of homeless people in Hong Kong.

Design: A cross sectional epidemiological survey involving clinical oral examinations and face-to-face interviews with 147 homeless participants. Clinical examinations were carried out following WHO criteria.

A randomized double blinded study to assess the efficacy of a laser-guided collimator on dental radiography training.

Objectives: To assess the effect of a laser-guided collimator in intraoral radiography training.

Methods: A custom-made collimator with four red laser diodes on each corner on the rim of an aluminium alloy cubic housing was fabricated. The laser used low power diodes, which are classified as laser-safe by the United States Food and Drug Administration (FDA).

Characterization of switch phenotypes in Candida albicans biofilms.

The aim of this study was to characterize switch phenotypes in Candida albicans biofilms. Cells of Candida albicans 192887g biofilms (24 h) were resuspended and these together with their planktonic counterparts were separately inoculated on Lee's medium agar supplemented with arginine and zinc, at 25 degrees C for 9 days, for colony formation. The different switch phenotypes, as reflected by varying colony morphologies, were then examined for their (i) stability under various growth conditions, (ii) carbohydrate assimilation profiles, (iii) susceptibility to the polyene antifungal, nystatin, (iv) adhering and biofilm-forming ability, (v) filamentation, and (vi) growth rate in yeast nitrogen base medium supplemented with 100 mM glucose.

The use of new probes and stains for improved assessment of cell viability and extracellular polymeric substances in Candida albicans biofilms.

Phenotypic and genotypic cell differentiation is considered an important feature that confers enhanced antifungal resistance in candidal biofilms. Particular emphasis has been placed in this context on the viability of biofilm subpopulations, and their heterogeneity with regard to the production of extracellular polymeric substances (EPS). We therefore assessed the utility of two different labeled lectins Erythrina cristagalli (ECA) and Canavalia ensiformis (ConA), for EPS visualization.

A testing machine for dental air-turbine handpiece characteristics: free-running speed, stall torque, bearing resistance.

The measurement of performance characteristics of dental air turbine handpieces is of interest with respect to product comparisons, standards specifications and monitoring of bearing longevity in clinical service. Previously, however, bulky and expensive laboratory equipment was required. A portable test machine is described for determining three key characteristics of dental air-turbine handpieces: free-running speed, stall torque and bearing resistance.

In vitro growth, acidogenicity and cariogenicity of predominant human root caries flora.

Streptococcus mutans (Sm), Lactobacillus acidophilus (La) and Actinomyces israelii (Ai) have been associated with root surface caries, which is an increasing problem in elderly Chinese. The aim of this study therefore, was to evaluate in vitro, the growth, acidogenicity and cariogenicity of these organisms, both in mono- and co-cultures using an in vitro model. Forty-eight root specimens were prepared using intact extracted human molars.

Oral health status of institutionalised elderly in Hong Kong.

Objectives: To describe the oral health status of institutionalized elderly in Hong Kong.

Methods: Older adults in 56 elderly homes were clinically examined in the institution by one of two calibrated dentists using standard methods recommended by the World Health Organization. Information on their perceived oral health status and behaviour was obtained from an interview.

Outreach dental service for persons with special needs in Hong Kong.

The authors describe the acceptance and efficiency of an outreach dental service, which provided oral health care to persons with special needs in Hong Kong. Portable dental equipment was transported to various institutions. Basic dental care including prevention, scaling, restoration, extraction, and denture repair was provided free of charge.

Clinical evaluation of packable and conventional hybrid resin-based composites for posterior restorations in permanent teeth: results at 12 months.

Background: Packable resin-based composites and simplified resin bonding systems are marketed to offer many advantages over conventional posterior hybrid composites and total-etch bonding systems. The authors conducted a study to evaluate the initial clinical performances of a packable and a conventional hybrid resin-based composite used with a simplified bonding system.

Methods: A total of 57 Class I and 45 Class II restorations were placed in the permanent teeth of 65 adult patients.

Maintaining dental education and specialist dental care during an outbreak of a new coronavirus infection. Part 2: Control of the disease, then elimination.

On Thursday 27th March 2003 the decision had been made to stop all clinical teaching and all non-elective patient care at the Prince Philip Dental Hospital, the teaching hospital of the Faculty of Dentistry of the University of Hong Kong. A lethal respiratory disease of unknown aetiology was spreading through the community but also in medical hospitals where it was infecting healthcare workers with apparent ease. Infections in an apartment block called Amoy Gardens seemed to have taken place by the deadly long distance airborne transmission route.

Value gaps in dental practice: understanding how differences in core values can adversely affect the practice.

Background: The authors explore the importance of human values in dental practice, an area often overlooked as we struggle to deal with the everyday demands of treating patients and managing staff members. Such values are, however, fundamental to the success of any practice; therefore, it is important to understand their significance.

Conclusions: Problems arise in dental practices when gaps develop between the values held by the various players involved (that is, between the entire dental team and patients, the dentist/owner's personal values and business goals, the dentist/owner and staff members, and the dental practice and any third-party funding organizations).

Maintaining dental education and specialist dental care during an outbreak of a new coronavirus infection. Part 1: a deadly viral epidemic begins.

During the three months from March 2003 the economically vibrant city of Hong Kong was seriously dislocated after becoming 'second port of call' of the new and potentially fatal disease, Severe Acute Respiratory Syndrome (SARS). The uncertainties during that period had a significant impact on the provision of dental care. However the city's only dental hospital continued to function and to support the Faculty of Dentistry of the University of Hong Kong in educating dental students and other members of the dental team.

Artificial mouth model systems and their contribution to caries research: a review.

The complexity of the oral environment, and ethical problems associated with studies of oral diseases in humans inevitably directed the attention to development of laboratory models, that simulate the human oral microcosm. These developments and in particular the in vitro 'artificial mouth' systems have progressed from simple and basic apparatus devised by Magitot and Miller at the end of 19th century to the currently available, highly sophisticated, computer-controlled, multi-station artificial mouth systems. These advances have metamorphosed from the early studies devised primarily to investigate factors affecting the carious process to the present designs that evaluate growth, pathogenicity, metabolism and mineralization of dental plaque under highly controlled conditions.

Longevity of two-unit cantilevered resin-bonded fixed partial dentures.

Purpose: To examine the clinical performance of two-unit cantilevered resin-bonded fixed partial dentures that were inserted at The Prince Philip Dental Hospital, Hong Kong by students and staff between 1992 and 1998.

Materials And Methods: A search of the Hospital computer records system revealed a list of 130 patients who had received two-unit cantilevered resin-bonded fixed partial dentures (RBFPD) placed more than 24 months previous to the review date. For each patient clinically examined, the following data were recorded: gender, age, operator, cementation date, endodontic treatment if performed, bone support, tooth mobility, the presence of shimstock contacts on abutment or pontic in intercuspal position, the presence of interproximal contacts adjacent to the prosthesis assessed by dental floss.

Pressure and temperature changes in heat-cured acrylic resin during processing.

Objectives: The aims of this study were to measure the pressure and temperature changes of acrylic resin during processing, to record the highest temperature reached when fast cured in boiling water and to determine the elevated boiling point of monomer under high pressure.

Methods: A subminiature pressure transducer (temperature compensated to 94 degrees C) and a thermocouple were placed on the palate of a standardized maxillary complete denture base. A heat-cured resin (Trevalon C) was polymerized by a long heating cycle (72 degrees C for 6.

Micro-tensile bond strengths to sclerotic dentin using a self-etching and a total-etching technique.

Objectives: To evaluate the in vitro regional micro-tensile bond strengths of a self-etching/self-priming adhesive system to sclerotic dentin, in the absence or presence of phosphoric acid conditioning.

Methods: Naturally-occurring, non-carious cervical lesions on extracted premolars were hand-cleaned with a slurry of pumice and chlorhexidine, then bonded without further cavity preparation. One group was bonded using Clearfil Liner Bond 2V (Kuraray Co.

Two modes of nanoleakage expression in single-step adhesives.

Self-etch adhesives that etch, prime, and bond simultaneously should not exhibit incomplete resin infiltration within hybrid layers. We hypothesized that nanoleakage patterns in these systems are artifacts caused by mineral dissolution in mildly acidic silver nitrate. Resin-dentin interfaces bonded with four single-step, self-etch adhesives were examined for nanoleakage by conventional (pH 4.

Sintering of dental porcelain: effect of time and temperature on appearance and porosity.

Objective: Mechanical condensation of powder-method dental porcelains can only achieve a limited effect--the majority of consolidation and porosity elimination is achieved by sintering. However, there is a surprising lack of information on the process in the literature, and the effects of the two basic conditions of sintering, time and temperature, are very poorly described despite theoretical expectations. The present study was to investigate the effects of these conditions on porosity and to consider its relationship to the recognizable firing stages of low and high biscuit, and other aspects of appearance, with a view to schedule recommendations.

Comparison of pulse activation vs conventional light-curing on marginal adaptation of a compomer conditioned using a total-etch or a self-etch technique.

Objectives: This study investigated the effect of two factors: conditioning methods and light-curing techniques on the marginal adaptation of Dyract AP (Dentsply DeTrey, Germany). The 'pulse activation' curing technique was compared with a conventional light-curing technique for their effectiveness in reducing marginal gaps in restorations that were conditioned with three different protocols.

Materials And Methods: Cylindrical cavities, 3mm in diameter, were prepared in extracted human molar teeth.

Fractional inhibitory concentration index of combinations of antibacterial agents against cariogenic organisms.

Objectives: To examine the inhibitory effects between paired combinations of four antibacterial agents that have been investigated in dentistry against six bacteria associated with dentinal caries.

Methods: The antibacterial agents tested were: chlorhexidine dihydrochloride, benzalkonium chloride, cetrimide and cetylpyridinium chloride. Two organisms each belonging to Streptococcus, Lactobacillus and Actinomyces species were evaluated against these agents.

The physical mechanisms of complete denture retention.

The purpose of this article is to assist the practitioner to understand which factors are relevant to complete denture retention in the light of the current understanding of physics and materials science and thus to guide design. Atmospheric pressure, vacuum, adhesion, cohesion, surface tension, viscosity, base adaption, border seal, seating force and muscular control have all been cited at one time or another as major or contributory factors, but usually as an opinion without proper reference to fundamental principles. Although there has been a detailed analysis published, it seems appropriate that a restatement of the points in a collated form be made.

The minimum inhibitory concentration of oral antibacterial agents against cariogenic organisms.

The minimum inhibitory concentrations (MIC) of eight common dental antibacterial agents against three genera of bacteria which have been implicated in dentine caries, namely streptococci, lactobacilli and actinomycetes were investigated. The ultimate aim was to determine the most appropriate antibacterial agent which could be added to dental restorative materials for filling cavities where there was residual dentine caries. The antibacterial agents tested were chlorhexidine diacetate, chlorhexidine dihydrochloride, chlorhexidine gluconate, benzalkonium chloride, cetrimide, cetylpyridinium chloride, thymol and sodium hypochlorite.

An ultrastructural study of the application of dentine adhesives to acid-conditioned sclerotic dentine.

Objective: This in vitro study examined the ultrastructure of resin-infiltrated sclerotic dentine following the application of a self-etching primer, with or without the adjunctive use of phosphoric acid pre-conditioning.

Materials And Methods: Non-carious, natural cervical sclerotic lesions were hand-cleaned with a slurry of pumice and chlorhexidine and bonded without further cavity preparation. One group was bonded using Clearfil Liner Bond 2V (Kuraray Co.