1. Introduction Parafunctional habits are recognized as a major etiological factor for the development of dental malocclusion. Thumb sucking and tongue thrusting are the most commonly seen oral habits (fig1) incorporates a tongue bead, a palatal crib and a U-loop which is attached to the molar bands on either sides. (a) (b) Figure 1 Hybrid Habit Correcting Appliance (HHCA). The tongue bead (Figure 1(a)) consists of a spinnable acrylic bead of 3 mm diameter. The appliance is designed to position the acrylic bead over the posterior one-third of the incisive papilla. The bead acts as a tongue retrainer. The patient is asked to constantly pull the bead towards the posterior region of the mouth. The patient is also advised to make sure that his tongue wedges between the bead and the roof of the mouth as he swallows. The palatal crib (Figure 1(b)) and the U-loop are made of 0.9 mm stainless steel wire. Three to four spurs are bent on either sides of the bead, starting from the canine region on one side, running anteriorly as a smooth curve (in conventional crib appliances, the cribs run obliquely from one canine to the other side canine) and lying 1 mm lingual to the cervical margin of the maxillary anterior teeth. In the region of the incisive papilla, the acrylic bead is incorporated in such a way that it lies over the posterior one-third of the incisive papilla. The tip of the crib should be almost in line with the incisor tip of the maxillary central incisor or 2 mm longer without interfering with the lower incisors when in occlusion. In cases with anterior open bite, the crib should be longer and can be up to 3/4th of the interincisal distance between the upper and lower central incisors. This is to avoid the tongue from thrusting over the tip of the crib. The palatal crib acts as a barrier against the thrusting tongue and works as a mechanical restrainer. The U-loop (Figure 1(c)) is incorporated in the second premolar region and it helps to reposition the appliance posteriorly during the retraction phase, when it is used along with fixed orthodontic appliances. The appliance can be engaged into a lingual sheath (Figure 2(a)) on the molar bands or can be soldered directly to the molar band (Figure 2(b)). If it is engaged in a lingual sheath, a tight ligature tie should be wound around the lingual sheath and the distal end of the appliance to avoid the appliance from slipping out of the sheath into the oral cavity. (a) Engaging in lingual sheath (b) Soldering Figure 2 Appliance secured to molar band by (a) engaging in lingual sheath and (b) soldering.
