The objective of this retrospective study was to investigate what percentage of the dental students in the University of Malaya has a tooth size discrepancy. The sample comprised 40 good quality pre-treatment study models with fully erupted and complete permanent dentitions from first molar to first molar, which were selected from the dental students of the University of Malaya. The mesiodistal diameter tooth sizes were randomly measured manually from first molar to first molar using digital calliper (Mitutoyu) accurate to 0.01 mm, and the Bolton analyses for anterior and overall ratios were calculated by scientific calculator. Reproducibility analysis for intra- and interexaminer calibrations was assessed by measuring 10 study models twice, a week apart. A paired sample t-test and the correlation coefficient were used to evaluate the systematic and random errors of the measurements using Statistical Package for Social Sciences (SPSS) version 12.0. The reproducibility of the intra and inter-examiners for the sum of upper and lower mesiodistal tooth size were high (average mean difference = 0.62, r = 0.82). This study found 47.5% of the samples had anterior, and about 10% had overall· tooth width ratios greater than 2 standard deviations from Bolton's mean. Large percentage of the dental students of the University of Malaya has tooth size discrepancies outside of Bolton 2 standard deviations. It would seem prudent to routinely perform the tooth size analysis and include the findings into orthodontic treatment planning.
This work presents the characterization of selected bioactive compounds of local herbs
through their photonic spectrum. A Shimadzu spectrophotometer was used to map bioactive
compounds extracted from Andrographis paniculata, Ficus deltoidea, Orthosiphon stamineus
and Centella asiatica. Dominant peaks and repeatability were the determinant parameters
in this study. Absorbance peaks of bioactive compounds were calibrated against respective
standardized chemicals obtained from reputable suppliers. The results obtained indicated
that absorbance peaks from different bioactive compounds could be identified by photonic
spectrum. Most bioactive markers were detected within the wavelength range of 200 nm to 350
nm, using a Deuterium (190 nm to 450 nm) light source and corresponding refraction grating.
A mathematical relationship of concentration versus absorbance at different wavelengths for
selected bioactive compounds were identified. The significance of the photonic characterization
of these phytochemicals forms the basis for a mathematical model in a decision support system
of a proposed mobile sensor prototype development.