The relationship between the mid-point and most-prominent point on the labial curve of upper anterior teeth

OBJECTIVES

This study investigates coincidence of the most-prominent point and the mid-point on upper anterior teeth in relation to the use of straight-wire appliances.

MATERIALS AND METHODS

Alginate impressions of the upper jaw were obtained from forty Caucasian patients. Impressions were cast using hard dental stone. The teeth on each upper study model (canine to canine) were marked along the facial axis of the clinical crown (FACC line) then separated using a very thin diamond disc. Each tooth was mounted on a glass slide using sticky wax and cut into two halves down this FACC line. Images were acquired of the sections and a straight line connecting the gingival margin and the incisal edge was drawn on the flat cut surfaces (now the proximal crosssectional view). From this line, perpendicular lines were drawn at the mid-point and most prominent point to the labial curve. Coincidence rate was calculated or whether the most prominent point was gingival or incisal to the mid-point.

RESULTS

Approximately 80% of upper central incisors had coincident mid- and most-prominent points. Upper lateral incisors and canine teeth had approximately 50% coincidence. The vast majority of cases without coincidence showed the most-prominent point incisal to the mid-point for all tooth kinds with just 5% or less gingival.

CONCLUSIONS

The high proportions of non-coincident examples found suggest that clinicians should be aware of individual variation and that this may possibly effect 3(rd) order alignment.

Gingival inflammation assessment by image analysis: measurement and validation

AIM

Gingival inflammation may be caused by injury or plaque-related diseases and reduction in inflammation can be a useful indicator of gingival recovery. There has been little research on development of non-index methods to measure gingival condition. The aims of the study were to investigate the reliability of the measurement of changes in gingival redness and swelling, using image analysis, and to compare this approach with an established method for assessing gingival overgrowth [J Clin Periodontol 28 (2001) 81].

METHOD

Twenty volunteers with gingival inflammation were recruited and digital images were taken. Duplicate measurements were made on the first visit by two examiners. At a subsequent visit following periodontal treatment, second images were taken. Gingival changes were determined by assessing redness and tooth surface area visible between the level of the inter-proximal papillae and the gingival margin. Tooth area measurements were compared with the established gingival overgrowth method.

RESULTS

The method showed excellent reliability for both intra- and inter-examiner measurements of 0.968-0.998 and 0.769-0.947, respectively, according to the classification by Donner and Eliasziw of the Fleiss coefficient of reliability (repeat measures taken during the patients' first attendance). High correlation was found for gingival encroachment when compared with the established gingival overgrowth method.

CONCLUSION

This technique proved a reliable method for investigating changes in gingival redness. High correlation was found for gingival encroachment when compared with an established method.

Is formal training necessary for capsule endoscopy? The largest gastroenterology trainee study with controls

BACKGROUND

Little is known about the infrastructure to train gastroenterologists in capsule endoscopy. The level of capsule endoscopy exposure among trainees in the United Kingdom or Europe has also not been quantified.

AIMS AND METHODS

To assess the ability of 10 gastroenterology trainees with endoscopy experience to interpret 10 capsule endoscopy videos against five medical students, with an expert in capsule endoscopy as the gold standard. Parameters assessed included gastric emptying time, small bowel transit and the diagnosis made. A questionnaire survey assessed the level of capsule endoscopy exposure among United Kingdom trainees.

RESULTS

Trainees were better at determining the gastric emptying time (p=0.013) and more likely to record true positives compared to the students (p=0.037). They were also less likely to record false positives (p=0.005) and more likely to reach the correct diagnosis (p=0.001, OR 3.6, CI 1.8-7.4). Our survey found that, 65% of trainees had prior exposure to capsule endoscopy but only 13% had done capsule endoscopy reporting. Sixty seven percent felt capsule endoscopy should be incorporated into their training.

CONCLUSION

This study has shown that prior endoscopic experience enables trainees to interpret capsule endoscopy more accurately than medical students. However, there is a demand for focussed training which would enable trainees to reliably interpret pathology on capsule endoscopy.

Measurement of stain on extracted teeth using spectrophotometry and digital image analysis

AIM

The aim of this study was to assess the reliability and validate a customized image analysis system, designed for use within clinical trials of general dental hygiene and whitening products, for the measurement of stain levels on extracted teeth and to compare it with reflectance spectrophotometry.

METHOD

Twenty non-carious extracted teeth were soaked in an artificial saliva, brushed for 1 min using an electric toothbrush and a standard toothpaste, bleached using a 5.3% hydrogen peroxide solution and cycled for 6 h daily through a tea solution. CIE L* values were obtained after each treatment step using the customized image analysis system and a reflectance spectrophotometer. A statistical analysis was carried out in SPSS.

RESULTS

Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.996 and 0.946 respectively. CIE L* values were consistently higher using the image analysis compared with spectrophotometry, and t-tests for each treatment step showed significant differences (P < 0.05) for the two methods. Limits of agreement between the methods were -27.95 to +2.07, with a 95% confidence of the difference calculated as -14.26 to -11.84. The combined results for all treatment steps showed a significant difference between the methods for the CIE L* values (P < 0.05).

CONCLUSION

The image analysis system has proven to be a reliable method for assessment of changes in stain level on extracted teeth. The method has been validated against reflectance spectrophotometry. This method may be used for pilot in vitro studies/trials of oral hygiene and whitening products, before expensive in vivo tests are carried out.

The variability of the curvature of the labial surface of the upper anterior teeth along the facial axis of the clinical crown

OBJECTIVE

To mathematically assess the curvature of upper anterior teeth along the facial axis of the clinical crown (FACC) line to provide information valuable for assessment of enamel growth.

METHODS

Forty upper study models were chosen from the Orthodontic clinic at the Charles Clifford Dental Hospital, Sheffield, UK. The study model incisors and canines were sectioned longitudinally down the FACC line, using a Microslice II cutting machine. Images were captured that showed the proximal view of the tooth curvature from incisal edge/cusp tip to the gingival margin. The images were converted into silhouettes and saved as bitmap files. These were vectorised and converted to an outline of xy data points. The forty xy files were mathematically adjusted so the distance between incisal edge and gingival margin were of equal length. Non Rotational Principal Component Analysis (PCA) was then applied at 20 equal intervals along the curve of each xy file to describe the shape of the teeth.

RESULTS

Intra class correlation coefficient for intra-operator repeatability ranged from 0.821-0.998 showing good or excellent levels of reliability. PCA showed variation between tooth types.

CONCLUSIONS

The method proved reliable. All tooth types showed that the mid-point region had the greatest rise variable, indicating that the most-prominent point was central or incisal for central and lateral incisors. All were skewed towards the incisal end and had kurtosis at both ends. Central incisors showed least variability. Greater variability was seen within the incisal third than within the gingival third for all tooth types.