Biomedical subjects

D Bister

Publications and source records attributed to D Bister.

4 recordsLinked to original sources

PubMed2006

Comparison of 10 digital SLR cameras for orthodontic photography.

Digital photography is now widely used to document orthodontic patients. High quality intra-oral photography depends on a satisfactory 'depth of field' focus and good illumination. Automatic 'through the lens' (TTL) metering is ideal to achieve both the above aims. Ten current digital single lens reflex (SLR) cameras were tested for use in intra- and extra-oral photography as used in orthodontics. The manufacturers' recommended macro-lens and macro-flash were used with each camera. Handling characteristics, colour-reproducibility, quality of the viewfinder and flash recharge time were investigated. No camera took acceptable images in factory default setting or 'automatic' mode: this mode was not present for some cameras (Nikon, Fujifilm); led to overexposure (Olympus) or poor depth of field (Canon, Konica-Minolta, Pentax), particularly for intra-oral views. Once adjusted, only Olympus cameras were able to take intra- and extra-oral photographs without the need to change settings, and were therefore the easiest to use. All other cameras needed adjustments of aperture (Canon, Konica-Minolta, Pentax), or aperture and flash (Fujifilm, Nikon), making the latter the most complex to use. However, all cameras produced high quality intra- and extra-oral images, once appropriately adjusted. The resolution of the images is more than satisfactory for all cameras. There were significant differences relating to the quality of colour reproduction, size and brightness of the viewfinders. The Nikon D100 and Fujifilm S 3 Pro consistently scored best for colour fidelity. Pentax and Konica-Minolta had the largest and brightest viewfinders.

Color↗

PubMed2005

A retrograde step.

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Education, Dental, Graduate↗

PubMed2002

Natural head posture--considerations of reproducibility.

This three-part study investigated the reproducibility of natural head posture (NHP) using radiographs and photographs. In part 1, reproducibility of cephalograms 1 year after the introduction of NHP was investigated and found to be less favourable (Dahlberg coefficient of 2.99 degrees) than most other previous investigations. In order to minimize radiation exposure of patients, reproducibility of photographs and method agreement between photographs and cephalograms were investigated in part 2. Reproducibility of the two photographs was poor (2.71 degrees). However, method agreement between cephalograms and the photographs taken at the same time was good (1.39 degrees). Replacement of the radiographic method with the photographic method for assessing NHP reproducibility appeared justified. Changing the protocol for achieving NHP in part 3 of the study improved reproducibility substantially (1.41 degrees). Various statistical methods were used to assess reproducibility and method agreement. Bland and Altman's graphical representation was found to be the most appropriate for method agreement. The Dahlberg coefficient, commonly used to assess NHP repeatability/reproducibility, does not provide an extreme enough interval to allow a sufficient clinical assessment of a method to be undertaken, compared with the reproducibility coefficient. That is, the latter provides a 95 per cent range, compared with 52 per cent with Dahlberg.

Cephalometry↗

PubMed1997

Continuation of decline in prevalence of anemia in low-income children: the Vermont experience.

OBJECTIVE: To examine whether the prevalence of childhood anemia in white low-income children has continued to decline into the 1990s. DESIGN: An examination of 14 years of hematocrit data from the Centers for Disease Control and Prevention's Pediatric Nutrition Surveillance System in Vermont from 1981 through 1994. SETTING: Public health clinics for the Special Supplemental Nutrition Program for Women, Infants, and Children in Vermont. The same screening method and criteria for identifying and defining anemia and the same quality-assurance procedures were used during the 14 years. The program eligibility criteria were also consistent except for part of 1991 and 1992. MAIN OUTCOME MEASURE: The annual prevalence of anemia. RESULTS: Between 1981 and 1994, the prevalence of anemia halved (from 7.9% to 3.6%, P<.001). For children aged 6 to 24 months, this decline was from 7.8% to 4.6% (P<.001); for children aged 2 to 5 years, the decline was from 7.9% to 3.1% (P<.001). CONCLUSION: The decline in the prevalence of anemia among low-income children observed by the Centers for Disease Control and Prevention's Pediatric Nutrition Surveillance System up to the mid-1980s has continued into the 1990s in Vermont. This finding indicates that iron nutrition in infancy and early childhood is still improving.

Anemia↗