Class II malocclusion is one of the most prevalent orthodontic conditions throughout the world, and these deformities are mainly treated by using functional appliances in growing patients. The most popular myofunctional appliance used for correction of class II malocclusion is the versatile removable twin block appliance in growing patients. Twin block is designed for full time wear to take the advantage of all functional forces applied to dentition.

The cooperation of children and adolescents plays a major role in achieving the desired treatment outcome with twin block appliance. Objective measurement of wear time has been demanded in orthodontics for a long time. In cases of failure or stagnating treatment it helps to find possible explanations. Studies show that patients sometimes are not very honest or unrealistic concerning their reported wear times.

Therefore, different devices have been introduced to measure the objective wear time of removable appliances. Most of these devices consist of a thermal microsensor that is embedded in the appliances.4 But in the country like India where most of the time environmental temperature is more than mouth temperature, these thermal sensors will give a false result. So, need to design a low cost electronic timing device suitable for application in removable acrylic orthodontic appliances. In this study, pretested electronic timing device which uses sensor with a switch function to record wear time will be used.

The aim of this study is to measure the wear time and to evaluate treatment efficacy in relation to wear time with twin block appliance.