Despite orthodontic treatment(tooth moving) is dynamic act, many orthodontists have used mainly static evaluation method for evaluating effectiveness of the orthodontic appliances. They want to find which is better appliance, especially in the treatment results and treatment period, when they chose one appliance from sugessted appliances for obtaining same treatment goal. The author and colleagues invented and manufactured new machine for getting information about the relative effectiveness from many suggested orthodontic appliances and we named it Calorific machine. We used this Calorific machine to find the relative differences about tooth moving mechanism and tooth moving time between the Burstone´ s PLA(single force mechanism) and Molar-up´ s PLA(couple mechanism) for correcting the posterior cross bite. We measured the distance of tooth . moving on the occlusal X-ray film and recorded the moving time of the anchored(control elct o-thermal tooth) and lingually tipped lower second molars(experimental electro-thermal tooth) and then processed paired t-est by SAS program The results were as follows. 1. Molar-up´ s PLA showed more extrusive and horizontal movement than Burstone´ s PLA at the lingually tipped molar(p=0.0000). 2. There is no finding of tooth movement by Molar-up´ s PLA at the uprighted molar(p=o.3475) but Burstone´ s PLA showed a little change(02 mm) at the same molar(p=O.0001). 3. Burstone´ s PLA took 17.8 minutes for tooth moving but Molar-up´ s PLA took only 3.8 minutes(p=0.0001)