The evaluation of the formation or the emergence of a single tooth can be a valuable indicator for clinical diagnosis and treatmen planning, but the evaluation of the whole dentition either by calcification stages or emergence or both, is a unique way for the determination of dental maturity as a system, similar to the skeletal system. But unlike the skeletal system, the dentition has two sets of teeth, the primary and the permanent dentition. There are also two ways of evaluating dental maturity: by recording the emergence or scoring the calcification stages. It has already been shown that the use of calcification criteria is a better, approach for the evaluation of teeth because consecutive radiographs can give us a continuous picture of the whole process of dental maturation. The only drawback of this approach would be the radiation hazards especially for very young children. This is one of the reasons that in some studies only the clinical emergence criteria are used for the evaluation of the primary dentition.