a virtual orthodontic treatment method and a system thereof , the method comprising the following : providing a virtual diagnostic setup model of teeth of at least one jaw of an individual , associating each teeth in said model with its corresponding virtual orthodontic appliance to obtain a first composite model and repositioning teeth into an initial treatment state according to pre - defined appliances - dependent rules . in the initial treatment state , selecting one or more teeth and reassociating the teeth with their corresponding virtual orthodontic appliance by changing the position of the appliance corresponding to the selected tooth thereby causing repositioning of the teeth according to the appliance - dependence rules . an altered treatment state is obtained , yielding a better grade , according to one or more systems for grading an orthodontic model , as compared to the grade of the initial treatment state .