The erosive effects of saliva following chewing gum on enamel and dentine: an ex vivo study.

Objectives: The primary objective was to determine the erosive effect of expectorated saliva, following chewing acidic gum, on enamel and dentine samples, using a non-acidic gum as a negative control. Secondary objectives were to determine the effect of brushing enamel and dentine samples and the effect of individual saliva pH and buffering.

Design: A single-centre, single-blind, placebo-controlled, two-way crossover study.

Comparative stain removal properties of four commercially available denture cleaning products: an in vitro study.

Objectives: Formulations of commercially available denture cleaners vary widely. Unfortunately, comparative data to suggest which products are the most effective can become invalid as newer products are introduced or formulations are changed. The aim of this in vitro study was to measure the stain removal properties of four currently available denture cleaners.

Teaching dental pain with and without underlying oral physiology: learning implications.

This study investigated whether teaching undergraduate dental students the diagnosis and management of acute dental pain alongside the underpinning oral physiology helped them to understand the topic better than teaching them acute dental pain as a separate entity. Each of three clinical years of dental students at the same dental school was taught in two groups. Each group was taught the signs/symptoms of five acute dental pain conditions by the same member of the staff.

Evaluation of the strength and radiopacity of Portland cement with varying additions of bismuth oxide.

Aim: To study the effect of addition of various proportions of bismuth oxide on compressive strength and radiopacity of Portland cement.

Methodology: The compressive strength of white Portland cement and cement replaced with 10, 15, 20, 25 and 30% bismuth oxide was evaluated by testing cylinders 6 mm in diameter and 12 mm high. Twelve cylinders were tested for each material under study.

Denture cleansers, soft lining materials and water temperature: what is the effect?

Aim: To investigate the effect of water temperature, in association with four denture cleansers, on the colour and surface roughness of five soft lining materials.

Method: Two silicone soft lining materials (Molloplast B and Sofreliner) represented the heat-cured, laboratory-based and chairside materials that are available. The wide range of chairside, acrylic resin-based, temporary soft lining materials was represented by Coe-Soft, Viscogel and Eversoft.

The effect of a range of disinfectants on the dimensional accuracy and stability of some impression materials.

Disinfection of dental impressions should be considered as a routine procedure in dental surgeries and dental laboratories. Disinfectants can have deleterious effects on some properties of impression materials. The aim of this study was to evaluate the dimensional accuracy and dimensional stability of a model dental stone, reproduced from five commonly used impression materials (Aquasil soft putty/Aquasil Ultra LV; Aquasil Monophase; Aquasil Ultra Heavy; Impregum F and Provil putty/Provil Light CD wash) retained by their adhesives in acrylic resin trays and exposed to three disinfectant solutions (Perform ID; Haz-Tabs and MD 520).

The effect of a range of disinfectants on the dimensional accuracy of some impression materials.

In this study the dimensional accuracy of two model materials; dental stone and plaster of Paris, reproduced from three commonly used impression materials; alginate, polyether and addition-cured silicone, retained by their adhesives in acrylic resin trays and exposed to four disinfectant solutions was evaluated. Ninety casts were used to investigate the effect of the four disinfectants on the dimensional accuracy of alginate, polyether and addition-cured silicone impression material. For each impression material 30 impressions were taken, half were poured in dental stone and half in plaster of Paris.

The prevalence of dentine hypersensitivity in a hospital clinic population in Hong Kong.

Objectives: Dentine hypersensitivity is a common clinical finding with a wide variation in prevalence values. The aim of this study was to establish the prevalence of dentine hypersensitivity and to examine some associated aetiological factors in a cross-sectional study of patients visiting the Periodontology and Oral Hygiene Clinic at Prince Phillip Dental Hospital, Hong Kong over a three-week period.

Methods: 226 patients were examined over a three-week period using a triple syringe to administer a blast of cold air to confirm the diagnosis of dentine hypersensitivity.

Accuracy of adaptation of thermoformed poly(methyl methacrylate).

Thermoformed poly(methyl methacrylate) (PMMA) sheet is used to produce a number of different dental appliances such as stents, occlusal splints and baseplates for occlusal rims. The purpose of the present study was to measure the accuracy of adaptation of Perspex PMMA sheet and to determine the effect of annealing on the accuracy of the thermoformed specimens. The results of the study showed that PMMA can produce specimens that are accurately adapted to the cast.

Knoop hardness depth profiles and compressive strength of selected dental composites polymerized with halogen and LED light curing technologies.

After the first light-emitting diode (LED) light curing units (LCUs) became available commercially, a comparison of mechanical properties between materials polymerized with conventional halogen lamps and this new technology was required. This study, therefore, investigated the curing performance of two conventional commercial halogen LCUs (Translux CL, Spectrum800), a custom-made LED LCU prototype, and one of the first commercially available LED LCUs (LUXoMAX). The Spectrum800 was adjusted to a similar irradiance to the custom-made LED LCU prototype.

Mechanical properties and radiopacity of experimental glass-silica-metal hybrid composites.

Objectives: Experimental glass-silica-metal hybrid composites (polycomposites) were developed and tested mechanically and radiographically in this fundamental pilot study. To determine whether mechanical properties of a glass-silica filled two-paste dental composite based on a Bis-GMA/polyglycol dimethacrylate blend could be improved through the incorporation of titanium (Ti) particles (particle size ranging from 1 to 3 microm) or silver-tin-copper (Ag-Sn-Cu) particles (particle size ranging from 1 to 50 microm) we measured the diametral tensile strength, fracture toughness and radiopacity of five composites.

Methods: The five materials were: I, the original unmodified composite (control group); II, as group I but containing 5% (wt/wt) of Ti particles; III, as group II but with Ti particles treated with 4-methacryloyloxyethyl trimellitate anhydride (4-META) to promote Ti-resin bonding; IV, as group I but containing 5% (wt/wt) of Ag-Sn-Cu particles; and V, as group IV but with the metal particles treated with 4-META.

The use of teledentistry to provide GDPs with advice in orthodontics.

This article describes a pilot trial to determine whether the transmission of digitized clinical records of potential orthodontic cases supported by access to video and data conferencing may help to reduce the current high level of inappropriate referrals to consultant orthodontists in the UK.

Some variables influencing the bond strength between PMMA and a silicone denture lining material.

Purpose: The purpose of the present study was to investigate the effect of roughening the denture base surface on the tensile and shear bond strengths of a poly(dimethylsiloxane) resilient lining material (Molloplast-B) bonded to a heat-cured acrylic resin denture base material. These measured bond strengths were compared to those obtained by packing the soft lining material against poly(methyl methacrylate) (PMMA) denture base acrylic resin dough.

Materials And Methods: Three groups of 10 specimens each were constructed for both tensile and shear tests.

Online orthodontic advice: a protocol for a pilot teledentistry system.

A prototype teledentistry service was established that incorporated a PC-based expert system designed to assist in orthodontic cases. It guided the general dental practitioner (GDP) through the assessment of a patient's malocclusion and helped ensure that all relevant clinical observations were made and details recorded. The resulting data file, containing radiographic images and clinical data, was then transferred via the Internet to a dental specialist.

The effect of the addition of surface treated chopped and continuous poly (methyl methacrylate) fibres on some properties of acrylic resin.

Poly (methyl methacrylate), the material most commonly used in the construction of dentures, is not without limitations particularly in terms of mechanical strength, such as flexural and fatigue strength. The Dental Practice Board for England statistics show that many dentures fail as a result of fracture. This study investigated the self-reinforcement of acrylic resin through the addition of surface treated poly (methyl methacrylate) fibres in chopped and continuous form.

Is paediatric day case tonsillectomy desirable? The parents' perspective.

Tonsillectomy is the most commonly performed otolaryngological procedure in most units. There is considerable financial pressure to perform paediatric tonsillectomy as a day case. Responding to concern that day case tonsillectomy might not be welcomed by parents or felt to be in the best interests of the patients, we carried out an audit of paediatric tonsillectomy, by means of a questionnaire for parents and nursing staff to complete while 32 consecutive patients underwent tonsillectomy as inpatients.

A clinic for the rapid processing of patients with neck masses.

Neck masses are common and may have serious underlying pathology. There is much anxiety and confusion in primary care as to which hospital department will provide the patient with the best service and the swiftest diagnosis. A clinic was set up at Wexham Park hospital to enable patients with neck masses to be seen early, and to undergo a one-stop specialist evaluation, ultrasound scan and fine needle aspiration biopsy.

Sudden parotid swelling due to spontaneous haemorrhage.

This paper presents an interesting case of a severe spontaneous haemorrhage within the parotid gland in an adult. A rapidly enlarging parotid mass with absence of causative trauma, inflammation or vascular abnormality, raised the suspicion of a neoplasm. Ultrasound, computed tomography (CT) and tissue biopsy, however, have shown only changes suggestive of previous haemorrhage and no evidence of malignancy.

Appropriate use of the day care unit for rigid endoscopy of the upper aerodigestive tract.

There is increasing pressure for more day surgery to be undertaken in the health service. In this retrospective study of 325 rigid upper aerodigestive tract endoscopies performed in the Day Care Unit of The Royal National Throat Nose and Ear Hospital, London, there were no post-discharge complications and only four patients required admission, none were, in our opinion, the direct result of day case rigid endoscopy. In our unit, the day case rate for microlaryngeal surgery is 44.

Clinical informatics and the dental curriculum. A review of the impact of informatics in dental care, its implications for dental education.

The origins of informatics lie in the development of computers and data processing techniques since the 1950s. The subsequent application of these to the practice of healthcare continues to the present day, so that information technology now holds the potential to revolutionise healthcare through more rapid and efficient management of an ever increasing quantity of clinical information. In dentistry, no less than in medicine, electronic systems can make an extremely valuable contribution to clinical practice.

Congenital anosmia.

Congenital anosmia is well described in conjunction with various sexual and other developmental abnormalities and has been reported to run in families. Congenital anosmia occurring as an isolated defect in a single family member is extremely rare, and tends to present late. We describe a case of a five year old girl with congenital anosmia and we outline the investigations which should be undertaken in such cases.

An assessment clinic for routine paediatric otolaryngological surgery.

In the current climate of medical practice clinicians are under constant pressure to come up with new ways of increasing efficiency and throughput whilst maintaining a high standard of patient care. Assessment clinics are not a new idea and are widely practised in the National Health Service. The novel feature of the clinic we are describing is that all relevant professionals are present: consultant otolaryngologist, audiologist, paediatric nurse, playleader and preassessment nurse.

The effect of surface treated UHMWPE beads on some properties of acrylic resin denture base material.

UHMWPE in the form of experimental surface treated beads was added to acrylic resin denture base material in various percentages to form a composite material. The influence on doughing and manipulation times, and transverse and impact strength was examined. The results indicated that the manipulation times, were not significantly affected as the percentage of UHMWPE beads in the acrylic resin powder increased.

The incidence and detection of HPV in the upper aerodigestive tract using brush and biopsy techniques.

The association between human papillomavirus (HPV) and squamous carcinoma is well established. In the polymerase chain reaction (PCR) we have an effective technique for detecting small quantities of viral DNA, but the assay requires tissue taken at endoscopy to reveal the presence or absence of HPV. Brushings have been used effectively elsewhere in the body to obtain cytological material.