After investigating 430 teeth of 346 patients having infected root canals after restorative procedures in four private practices, the following conclusions were obtained. 1. Upper and lower first primary molars were most susceptible to infected root canals. Upper second primary molars had the lowest susceptibility to infected root canals among all primary molars. 2. The peak age for obtaining restorative treatments was youngest in upper primary central incisors and it was 2 years. The highest peak age was 4 years in upper second primary molars. 3. In either restoration, more than half of the cases were treated without pulp capping. 4. The peak age for incidence of infected root canals after restorations was 4 years in upper primary central incisors. In these restored teeth, the more distally teeth were located, the higher peak age was observed; therefore, the peak age for upper and lower second primary molars was 5 or 6 years. 5. The duration between receiving restorative procedures and incidence of infected root canals was mostly within 6 months in upper first primary molars. Nevertheless, in almost 50 % of the other primary teeth except for lower and upper second primary molars, infection of root canals occurred within 1 to 1.5 years. 6. One third of children having infected root canals after restorations had some systemic diseases. On the other hand, two thirds of children were uncooperative at the time of restorations.

Above the results, it was revealed that deep caries requires pulp capping and close proximity to pulp should be taken into consideration during restoring teeth with thin tooth structure such as upper and lower first primary molars and upper primary central incisors. In such cases as treatments on uncooperative young children, it is suggested that provisional treatments should be performed first before providing final restorations.

Three-dimensional simulation is necessary for the case that a face form is asymmetry in orthodontic treatment. Authors developed the three-dimensional measurement system which used the grid pattern projection method. And we had reported about using it for dental cast measurement. Furthermore, we applied this principle and developed the three-dimensional measurement device of a face.

This report introduces the three-dimensional measurement device of the face which used the grid pattern projection method that was developed by us. And we report about clinical application of three-dimensional simulation of the face which used this device. It was difficult to predict a postoperative form of the face which was an asymmetry before. However, the patient is easy to have come to understand the change of postoperative facial form by performing three-dimensional simulation.

The three-dimensional simulation was effective as a material of informed consent of the case especially that had an asymmetry facial form in orthodontic treatment.