Biomedical subjects

Neil Pender

Publications and source records attributed to Neil Pender.

3 recordsLinked to original sources

PubMed2005

Mandibular arch changes following nonextraction treatment.

OBJECTIVE: To evaluate mandibular tooth position changes following treatment with a lip bumper and fixed appliance. Specifically, we aimed to determine how space was obtained to align crowded lower incisors. METHODS: Thirty-four consecutively treated children with a mean age of 10.6 years (SD: 1.14 years) were selected from a specialist orthodontic practice in Eire. All subjects were treated with a lip bumper followed by a fixed appliance. The positions and angulations of the lower first molars and most proclined lower incisor were measured on the pretreatment and post-treatment lateral cephalometric radiographs and study models with a reflex metrograph. The changes were also compared with published growth data. RESULTS: After lip bumper and fixed appliance treatment the mandibular arch depth decreased (Mean difference: 1.2 mm; p < 0.01) and the mandibular intermolar width increased (Mean difference: 1.73mm; p < 0.01). The mandibular molars moved mesially (Mean difference: 2.14 mm; p < 0.01 and tipped distally (Mean difference: 4.36 degrees; p < 0.01). There were no significant differences between the pre- and post-treatment positions or angulations of the mandibular incisors. Compared to published growth data the arch depth decreased less, the intermolar width increased more and the mandibular molars were uprighted. There was no difference in the positions of the mandibular incisors in the treated group compared with published growth data. CONCLUSIONS: The main effects of nonextraction treatment with a lip bumper followed by fixed appliance treatment were to maintain the leeway space, expand the mandibular arch and 'upright' the lower molars. The treatment had no effect on the position of the lower incisors.

Cephalometry↗

PubMed2003

Quantifying enamel demineralization from teeth with orthodontic brackets--a comparison of two methods. Part 1: repeatability and agreement.

The aim of this investigation was to compare the repeatability of measuring enamel demineralization surrounding an orthodontic bracket using two techniques: computerized image analysis from digitally converted photographic slides and quantitative light-induced fluorescence (QLF). Fifteen human molars were halved and shaped to look like incisors. The teeth were individually numbered and orthodontic brackets bonded to the buccal surface. The crowns were covered with acid resistant varnish, except for windows approximately 1.5 x 3 mm adjacent to the gingival, occlusal, mesial, and distal edges of the bracket. The windows were variously exposed to a demineralizing gel for 0, 3, 7, or 14 days, and the acid resistant varnish was removed. Standardized photographic slides and QLF images of the teeth were taken. These were repeated after 1 week. The slides were converted to grey scale digital format and analysed using Image-Pro Plus 3.0. The QLF images were stored, processed, and analysed using customized software. All images were recoded for blind analysis. The four surfaces of the bracket were inspected and only areas of suspected demineralization were analysed. This was repeated after 1 week. The limits of agreement and mean difference between repeat readings of the area of demineralization were similar for both techniques (-0.04 +/- 0.43 for photographs and -0.10 +/- 0.63 for QLF). Mean grey level (photographs) and mean loss of fluorescence from that area (deltaF) (QLF) showed acceptable limits of agreement. The Intra Class Correlation (ICC) was below 0.81 for the measurement of area from QLF, suggesting that random error needs to be reduced. There was evidence of systematic bias for the repeat readings of the grey levels from the photographs (P < 0.001). Enamel demineralization surrounding an orthodontic bracket can be measured reproducibly using these two techniques.

Bias↗

PubMed2003

Quantifying enamel demineralization from teeth with orthodontic brackets--a comparison of two methods. Part 2: validity.

This is Part 2 of an in vitro study investigating two techniques for recording and quantifying demineralization surrounding orthodontic brackets. In Part 1 the repeatability of computerized image analysis from digitally converted photographic slides and quantitative light-induced fluorescence (QLF) was explored. In Part 2 of the investigation the validity of each technique was examined. Thirty halved human molars, shaped to look like incisors and with an orthodontic bracket bonded to the buccal surface were used. A small area of each of the four edges of the bracket was variously exposed to a demineralizing gel for 0, 3, 7, or 14 days. Images of the teeth were taken and analysed using the two techniques. Repeat images and analysis were carried out blind. The sensitivity, specificity, positive, and negative predictive values were calculated. A negative result confirmed that there was no demineralization present in the majority of cases. A positive result was less reliable particularly for the occlusal and gingival regions. The 7- and 14-day demineralization patterns were detected every time using the photographic technique. The discrimination of the 0- and 3-day patterns was less reliable. The results of this study were extrapolated to allow for the prevalence of the condition following orthodontic treatment, and the implications of this for a putative clinical trial are discussed, together with the advantages and disadvantages of each method. Either technique would be applicable to use in a clinical trial.

Dental Bonding↗