Appliance breakages.

A survey of appliance breakages over a 12-month period revealed that the acrylic baseplate and bite planes (57 per cent) fractured more frequently than wire elements (43 per cent). The number of appliances broken represented about one in five of new appliances fitted during the period. More than half of the breakages were perpetrated by persistent offenders and 31 per cent of appliances broke while they were removed from the mouth, but in the care of the patient. Inadequate properties of the acrylic resin and carelessness on the part of the patient are suggested as the most important causative factors.