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The Integration of Functional and Fixed Appliance Treatment

There are many different treatment methods available for correcting the Class II problem. Some of the appliances include removable functional appliances, extra-oral forces applied through headgear, and Class II elastics to fixed appliances. Unfortunately, all of these methods rely on patient co-operation to some extent. Recently, there has been a revival of interest in the Herbst appliance (Pancherz, 1985) because it enables the correction of Class II problems with reduced need for patient co-operation. The Herbst appliance has been described as a fixed functional appliance.This is an upper and lower fixed appliance linked by a telescopic mechanism. This mechanism holds the mandible forward in a protruded position throughout treatment to modify mandibular growth. The appliance allows opening and closing movements of the mandible, and some lateral movement. The author has treated a number of cases with the Herbst appliance and the results were remarkable compared to other methods of Class II correction. It was the use of the Herbst appliance that prompted the author to develop the present appliance. The Herbst appliance suffers from problems of breakage of the constituent parts and this is in common with many of the inter-arch appliances used to correct Class II malocclusions.The Herbst appliance is also expensive and difficult to make. This is a preliminary report of a fixed system using acrylic occlusal blocks to protrude the mandible in a similar way to the removable twin-block appliance.The blocks are attached to bands cemented to the teeth. The Twin block appliance introduced by Clark (1988) is currently one of the most popular functional appliances used in the United Kingdom (Chadwick et al., 1997)