This study is intended to provide a referable information of exposed amount of maxillary central incisor of Korean by ages and gender under rest position. The result of this study will give guidelines for making prothesis. The subjects of this study are patients of Charmgoun Dental Hospital in Busan, Korea. A statistical analysis was conducted after taking digital photos of patients' teeth with a ruler and measuring the length of teeth on the computer program. The results of this study were as follows : 1. The length of maxillary central incisor that exposed under upper lip is decreased by increasing age in rest position.; the average length is 3.455mm in 20s, 2.525mm in 30s, and 1.543mm in 40s. 2. The exposal length in females is more than males, average length is 2.796mm in female and 2.342mm in male. However, there is not significant difference between the genders. 3. The exposed average length of maxiallry central incisor under upper lip is 2.618mm at rest. 4. The clinical crown average length of maxillary central incisor is 10.195mm, but incresing age, there is no significant defference. 5. There is significant difference between the genders in the clinical crown length of maxillary central incisor.; the length is 10.637mm in men, 9.90mm in women.

For the prosthodontic results which are compatible with esthetics to be fulfilled, the first prerequisite would be periodontal intervention and stability, the second one may be functional competency and the ultimate goal should be ascribed to esthetic considerations. Other words, esthetic dentistry is a whole entity which encompasses the biological stability of the periodontium, physical accuracy of the prosthodontic structure and finally, the beauty which can be found in natural dentition. It also implies the harmonized lip line which reveals the well-balanced tooth morphology and health gum profiles (Red-White Esthetics). Largely, there lie some differences in the input system of the 3-dimentional data from the prepared abutments between respective computer-assisted systems available now. But the manufacturing systems (CAM) are very similar between them, to say, comprise numeric control systems with whole 3-dimensional milling units according to the restorations to be made. Now the author is going to present CAD/CAM Zirconia All Ceramic Restoration on the topics for the Red-White Esthetics, periodontal control and maintenance, treatment for the discolored teeth, post & core build-up works for the devitalized teeth, characteristics of the Zirconium oxide All Ceramics, fabrication procedures, clinical considerations and its application to diverse clinical situations.