title: The relationship between plaque accumulation and anterior crowding in an adolescent orthodontic population
Creators: name: Maini, Anika
Publisher: name: University of Liverpool Repository
Year: 2012

description: Aim: To evaluate the longitudinal relationship of anterior tooth alignment and intra-oral plaque accumulation during orthodontic fixed appliance treatment, using novel intra-oral imaging techniques. Design: Prospective observational cohort study. Setting: Countess of Chester Hospital Subjects: 13 adolescent patients (9 females, 4 males) recruited prior to commencing fixed appliance therapy. The mean age of patients recruited was 13.4 years with an age range of 11.9 – 17 years. Methods: Clinical data were collected for each participant at consecutive appointments until the anterior teeth were aligned with the minimum follow-up being 6 months. Data included an assessment of plaque accumulation using a novel hand-held device (ToothcareTM) and upper and lower labial segment crowding was evaluated using sectional plaster models to determine the Little’s Irregularity Index [1975]. Repeat measures were used to assess reliability of the plaque scoring method and measurement of the Little’s Index via dial callipers and a reflex metrograph. The accuracy of hand scoring Little’s Index was also compared to the reflex metrograph measurements. Dahlberg’s method error formula was used to determine the accuracy of Little’s Index scores whilst Cohen’s Kappa statistic determined the degree of agreement in repeat plaque measurements. Uni-variate non-parametric statistics were used to assess any differences between test re-test measurements and Spearman’s Correlation Coefficient was used to determine associations between plaque and crowding over time. The multi-variate Kruskal-Wallis test was used to examine the trend of plaque and crowding over time. Results: Spearman’s Correlation Coefficient showed an inverse relationship between plaque and crowding over the course of the study (r = -0.375) although this association was very weak. The inverse relationship was stronger for the baseline data (prior to bonding of the fixed appliances) r = -0.602, which was statistically significant at the five percent level. There was no consistent trend amongst patients of plaque accumulation over time (p=0.741) although the degree of labial segment irregularity did consistently improve over the first three visits (p=0.038). Hand scoring with dial callipers showed acceptable accuracy with a method error of 0.17mm, although the reflex metrograph did not show the same consistency (method error = 0.22mm) and tended to over score the irregularity when compared to the hand scoring method (p=0.000). Reproducibility of the plaque scoring method was acceptable when using the ToothcareTM light at the chair side (un-weighted kappa statistic = 0.92) and when compared to an image from the digital camera based on the same technology, QLF-D BiluminatorTM (un-weighted kappa statistic = 0.76). Conclusions: The plaque scoring index based on a novel hand-held device (ToothcareTM) shows acceptable reliability and reproducibility. Measuring Little’s Irregularity Index [1975] by hand may be preferable to using a similar index on a reflex metrograph due to the increased error in the vertical dimension. Plaque accumulation does not appear to show a consistent trend over time and is very variable in nature. In this cohort there was a very weak and inverse relationship demonstrated between labial segment crowding and plaque quantity.