Effect of T4K Versus Twin Block in Developing Class II Division I Malocculsion

The pre-fabricated, hard, polyurethane, pink T4K™ (Myo functional research Co., Australia) was used in the study. It consisted of: facial bows, lingual bows / tongue guard, lingual tag / tongue tag, dental channels with a pre-determined bite position and a lip bumper. In the first week, the patients were instructed to gradually increase the wearing time of the appliance during the daytime. By the second week, the patients were instructed to wear the appliance achieving at least 8 hours during sleeping. The Trainer usually needs no adjustments. The patients were asked to place it themselves inside their mouths. The distal ends of the appliance were trimmed 2-3 mm with an acrylic bur on a straight hand piece if they were too long or the patient could not keep his lips together. By the end of the first 4 weeks, the patients were wearing the appliances minimum of 1 hour during the day plus the overnight wear following the manufacturer's instructions.

The twin block was used, and instructions were given to wear the appliance nearly full-time. Selective sequential inter-occlusal trimming was done monthly after the 2nd month in the occlusal surface of the maxillary bite blocks to clear over the mandibular molars allowing their eruption in a more favourable mesial direction and to increase the vertical dimension. Trimming was done in the fitting surface over the maxillary and mandibular premolars whenever needed to allow their full eruption and to level the occlusal plane