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Biomedical subjects

A Damien Walmsley

Publications and source records attributed to A Damien Walmsley.

10 recordsLinked to original sources
PubMed2004

Automated quantification of dental plaque accumulation using digital imaging.

OBJECTIVES: Most dental plaque indices have a subjective component due to investigator interpretation. To assess the accumulation of plaque on teeth, a fully automated method was developed based on digital imaging of methylene blue (1% (w)/(v)) disclosed plaque. METHODS: Intra-oral colour images of disclosed plaque from 25 individuals were coded into hue, saturation and intensity colour space. Unequivocal areas of clean teeth, plaque and clean gingiva were sampled to determine the typical values of hue, saturation and intensity of light. RESULTS: Discriminant analysis showed that the success rate for classification of the pixels as plaque and non-plaque was 87.3% based on saturation and intensity, and 98.7% for a classifier based on hue and intensity. Fisher's function coefficients were used to create classification boundaries in the colour space which would allow to automatically classify new images. CONCLUSIONS: This method has potential for automated and quantitative measurement screening of dental plaque that may be used to assess the efficacy of oral hygiene products and procedures.

Adult↗
PubMed2004

Management of peri-implant bone loss using guided bone regeneration: a clinical report.

This clinical report presents a patient who developed peri-implant bone loss around 2 maxillary endosseous root-form implants after restoration with cement-retained single crowns. Significant localized bone loss occurred around 1 of the implants due to retained excess cement. Reparative treatment consisted of a guided bone regeneration technique. Following a 9-month period of submerged healing, the implants were re-exposed and restored to complete function.

Adult↗
PubMed2004

Thermal imaging of ultrasonic scaler tips during tooth instrumentation.

OBJECTIVES: During ultrasonic scaling procedures, contact of the scaler tip with the tooth surface will produce frictional heating. The aim of this study was to assess this heat generation using an Agema 900 thermal imaging system. MATERIALS AND METHODS: Both the Cavitron sustained performance system (SPS) with TFI-3 tip and the Mini Piezon with P-tip were tested. Handpieces were fixed with their sides facing the thermal camera and thermal image sequences or "movies" created. Measurements were performed with tips under loads of 25, 50 and 100 g, at water flow rates of 10, 20 and 40 ml/min and low, medium and high generator power settings. A measurement point was superimposed on the resulting thermal images at the tip/tooth contact site and the temperature variation with time recorded. RESULTS: All combinations of instrumentation produced an increase in temperature. An increase in temperature was generally observed with increasing load (for given power/water), power setting (for given load/water) and a decrease in water flow rate (for given load/power). CONCLUSION: Heat generation is minimised by using low/medium power settings and light contact. Care must be taken to ensure adequate water is present at the site of instrumentation to prevent patient discomfort due to excessive heating.

Body Temperature↗
PubMed2004

Mandibular implant-retained overdenture with magnets: a case report.

Implant-retained overdentures can be a simple treatment option to restore the edentulous mandible. Retention can be achieved via studs, linked bar system or magnets. Success rates using the different retention mechanisms have been reported to be high. However, long-term prospective studies on implant-retained overdentures are limited. This paper reports on a patient who has successfully worn a mandibular implant-retained overdenture with magnets for 12 years.

Aged↗
PubMed2004

A novel method for the evaluation of powered toothbrush oscillation characteristics.

PURPOSE: To assess the vibration characteristics of oscillating objects with the scanning laser vibrometer (SLV). A laser is scanned over the surface of a vibrating target and the reflected, Doppler frequency shifted beam is used to determine the displacement amplitude and frequency of the vibration. This communication reports on a preliminary investigation to assess unloaded powered toothbrush oscillations, using Scanning Laser Vibrometry. METHODS: Four powered toothbrushes were selected for this study including the Sonicare, Philips/Jordan Sensiflex HX2520, Braun 3D and Braun D8. Each toothbrush was clamped in position and 10 area scans of their heads were taken from the side orientation to determine the displacement amplitude and frequency of oscillation. RESULTS: The fundamental frequency of oscillation of each brush was determined: Sonicare: 262.5Hz; Philips: 62.5Hz; 3D: 75Hz and D8: 62.5Hz. The maximum displacement amplitude (half the peak-to-peak excursion) for each brush (at the tips of the longest bristles) was Sonicare; 2.51 +/- 0.32mm, Philips; 2.60 +/- 0.15mm, Braun 3D; 2.14 +/- 0.18mm and Braun D8; 2.14 +/- 0.21.

Dental Devices, Home Care↗
PubMed2003

Acrylic partial dentures.

Acrylic removable partial dentures are routinely used in everyday clinical practice. However, there is concern that if they are not correctly designed that damage may result to the soft and hard tissues leading to tooth loss. This article reviews the potential damage that may occur from the use of acrylic dentures. Methods of improving the design features and construction of acrylic RPDs to minimize damage and improve longevity of the remaining teeth will be demonstrated.

Acrylic Resins↗
PubMed2003

Effect of loading on the vibration characteristics of thin magnetostrictive ultrasonic scaler inserts.

BACKGROUND: The ultrasonic scaler market has seen an increase in availability of thin inserts for periodontal pocket access. While such thin inserts may have advantages in negotiating the periodontal pocket, the relatively narrow structure may be prone to damping under load. The purpose of this study was to assess the vibration characteristics under load of thin, straight, ultrasonic scaler inserts. METHODS: Five types of thin inserts were each obtained from three manufacturers and were operated using an ultrasonic generator at medium power and low water. The displacement amplitude of the scaling tip was measured via a scanning laser vibrometer (SLV). Increasing forces up to 1.0 N were applied either to the base of the tip (up through its center) or while it was loaded from the side. Displacement measurements were obtained using the SLV under these loading conditions. RESULTS: Under loading, there was a drop in displacement amplitude of all tips. Furthermore, loading of the tips resulted in large variations of displacement amplitudes recorded. The mean tip displacements recorded ranged from 10 to 30 microm when unloaded and 7 to 25 microm when loaded. The fundamental frequency of the ultrasonic tips' oscillation was at 30 kHz. However, loading resulted in the production of additional subharmonic frequencies in the region of 6 to 10 kHz. CONCLUSIONS: Thin ultrasonic scaler tips are susceptible to loading. This results in a reduction in the displacement amplitude that shows variation not only between tips of different design but also between those of the same design made by the same manufacturer. Clinicians and researchers should be aware of this variability, which may influence both clinical procedures and future research with thin ultrasonic scaling tips.

Dental Enamel↗
PubMed2002

Technology, ultrasonics and dentistry.

Initially used to drill cavities in teeth, ultrasonic instrumentation may now be employed for descaling tooth surfaces, root canal preparation and in apical surgery. The probe tips used to perform these procedures are available in a variety of designs to enable easier access to different areas of the mouth. This article reviews the technology behind some of the present dental ultrasonic instruments and suggests ways in which that technology could be advanced.

Dental Instruments↗
PubMed2002

Magnetic retention in prosthetic dentistry.

Magnets are a popular method of attaching removable prostheses to either retained roots or osseointegrated implants. This paper reviews the development of magnets in dentistry and describes the different types of magnetic attachments that are available. The clinical applications of magnets in prosthetic dentistry are illustrated and future technological advancements indicated. Whilst different magnetic materials that mirrored the developing technology have been used, the main drawback to their use is the potential of corrosion of the magnetic material in the mouth. However, newly emerging technologies may provide a solution to this problem, allowing the continued use of magnets in prosthetic dentistry.

Corrosion↗