94th European Orthodontic Society Congress, Edinburgh, United Kingdom, 17 - 21 June 2018, pp.111
AIMS: To explore the characteristics of initially failed attachments during the indirect orthodontic bonding procedure.
MATERIALS AND METHOD: This data is a part of a randomized trial in which two different bonding trays were compared for the transfer accuracies of the attachments. As part of the transfer accuracy data collection all working models and patients’ arches were scanned after bracket placement with an intraoral scanner. A total of 384 brackets-tubes were prepared for indirect bonding in 16 patients. All bonding procedures were performed using a chemically cured adhesive and a tongue and cheek retractor along with high volume suction to prevent saliva contamination. Initially failed attachments were recorded after the bonding sessions. The localization of the failed attachments and the transfer accuracies of the bonded attachments neighbouring these failed attachments are described.
RESULTS: Sixteen (4.2%) of the brackets and tubes in seven patients initially failed. Two patients were particularly prominent with 5 and 4 initially failed attachments. Four of the failed attachments belonged to the incisor teeth, three to premolar teeth and nine to molar teeth. Three of the failed incisor brackets belonged to the same patient, suggesting the contamination of etched enamel which seemed possible due to the design of the retractor. Fifteen of the initially failed attachments were localized either in the most anterior or the most posterior part of the trays. Only one failed attachment had successfully bonded neighbouring attachments on both the mesial and distal sides (teeth 32 failed, but 31 and 33 were bonded in the same tray). Eight of the failed attachments were in groups of two adjacent teeth (25-26, 26-27, 41-42, 46-47). Five out of 11 bonded attachments neighbouring the terminal initial fail sites had torque problems during transfer (greater than 2°) suggesting that misfit of the bonding trays might be responsible for the initial failures.
CONCLUSION: These findings seem to agree with the common knowledge as the cause of initial bonding failures were attributed to technical issues and surface contamination. However, further studies are required order to understand specifically the reasons behind initial bond failures.