Direct bonding in orthodontic treatment and retention a post-treatment evaluation

Abstract

A post-treatment evaluation, after 9-20 months of routine orthodontic therapy, was made on the effectiveness of direct bonding with a chemically polymerized diluted composite material. A total of 612 brackets and buccal tubes on perforated metal backings were bonded to different teeth of 75 patients, including 237 incisors, 125 canines, 164 premolars and 86 first or second molars. To improve aesthetics, oral hygiene and gingival condition, slim bracket bases were used on all teeth and care was taken to use minute quantities of adhesive material. The same investigator bonded all the brackets and performed the orthodontic treatment. The results demonstrated an overall failure rate of 11 per cent for the whole treatment period. The brackets most prone to come loose were the maxillary first molars (27%), followed by the mandibular first (24%) and second (18%) molars. The failure rates on all other teeth were lower than 10 per cent, with the canines giving the lowest debonding rates (4-6%). An evident individual variation was noted, and a few patients had a high number of failures. Clinical and scanning electron microscopic studies of tooth surfaces following removal of the brackets demonstrated a ‘normal’ surface appearance when plain-cut tungsten-carbide burs rotated at low speed were used to remove composite material that could not be scraped off, while fine diamonds and even sand paper discs created marked surface scratching. It is concluded that carefully performed bonding techniques may be of value, particularly on anterior teeth, premolars and mandibular second molars, while the evidence at hand would suggest that first molars are better banded. Also, for retention purposes, direct bonding with composite material opens up a range of new possibilities, which seem to be very promising.