Dental crowding: a comparison of three methods of assessment

This study was designed to explore a new method for the assessment of dental crowding from study models, which would be both valid and reproducible. This was then tested against two previously reported strategies. A single examiner compared the following methods: visual examination, brass wire/callipers, and a reflex microscope with its customized computer program. Sixty study models (30 maxillary and 30 mandibular) were measured using each technique on two separate occasions. The results showed the reflex microscope method to be the most reproducible, followed by the visual examination and brass wire methods. When testing for validity, as there is no absolutely accurate standard of arch measurement, the individual methods must be compared with one another. From the results, it was seen that the mean values for dental crowding using the reflex microscope, in both the upper and lower arches, were very close to a value which equalled the average obtained from the two means of the visual examination and brass wire methods. The results also indicated that the visual examination and brass wire methods showed a positive bias towards over- and underestimating the degree of crowding, respectively.