3차원 적층가공과 밀링에 의해 제작된 일체형 의치의 인공치 변위 평가

Abstract

Artificial teeth movement of Monolithic Complete Denture manufactured by 3D Printer and Milling Machine.

Kwak, Young-hun, D.D.S. Advisor : Prof. Kim, Hee-Jung, D.D.S., M.S.D., Ph.D. Department of Prosthodontics, Graduate School of Chosun University

I. Introduction Conventional denture base preparation methods using polymethylmethacrylate(PMMA) cause a linear dimensional change of the denture base due to several factors in the process such as polymerization shrinkage of PMMA generated during the flasking process, thermal contraction during the flask cooling, and the deformation caused by the stress release during deflasking process. Such deformation of the denture base causes the movement of artificial teeth, resulting in an error in occlusion. Recently, the use of CAD/CAM has the advantage of reducing the number of visits, consultation hours, and deformation of denture base. The denture made using milling and 3D printing causes the displacement of artificial tooth by the amount of offset between the socket and the artificial teeth made on the denture base and the bottom shape of the artificial teeth. It is expected that the complete denture manufacturing method in which the denture base and the artificial teeth are machined in one time using Milling or 3D printing is less in displacement of the artificial teeth than the conventional method of bonding the artificial teeth to the denture base. However, there is no research yet on the extent of the displacement and whether the displacement is clinically acceptable.

II. Purpose The purpose of this study is to evaluate the displacement of artificial tooth of monolithic complete denture maunfactured by milling and 3D printing method in which the denture base and the artificial teeth are simultaneously made.

III. Material and Method To design the measurement point, the complete denture made by the conventional method was scanned by model scanner(Identica blue; Medit Co. Ltd., Seoul, Korea). The measurement points were set at both central incisors, both canines, and both first molars for each upper and lower denture. Twelve upper and lower complete dentures for each were made by milling and 3D printing method. The distance between measurement points was measured after scanning of all the dentures made. Group Up is a group of upper dentures made by printing, Group Lp is a lower denture group made by printing, Group Um is a upper denture group made by milling, Group Lm is a lower denture group made by milling, Group Uc is a group of finally designed upper dentures, and Group Lc is a lower denture group of finally designed lower dentures. Measurements were performed between both central incisors(AB, ab), both canines(CD, cd), both first molars(EF, ef), between an incisor and a first molar(AE, ae), and between incisor and lingual point(AG, ag) for each upper and lower denture.

IV. Result The measurement results of each group are shown in the following Table.

Table. 1. Mean value of Distance between measuring points in upper denture. Group AB CD EF AE AG Group Up 8.173 ± 0.065 33.048 ± 0.112 55.175 ± 0.193 33.924 ± 0.146 13.240 ± 0.083 Group Um 8.157 ± 0.092 32.994 ± 0.109 55.105 ± 0.138 33.924 ± 0.111 13.191 ± 0.119 Group Uc 8.095 ± 0.048 33.000 ± 0.041 55.114 ± 0.024 33.897 ± 0.060 13.318 ± 0.027 (Unit: mm) Table. 2. Mean value of Distance between Lower points (Unit: mm)

Group ab cd ef ae ag Group Lp 5.138 ± 0.115 26.680 ± 0.112 44.980 ± 0.127 29.777 ± 0.106 13.743 ± 0.103 Group Lm 5.208 ± 0.083 26.769 ± 0.132 45.092 ± 0.141 29.845 ± 0.147 13.694 ± 0.125 Group Lc 5.172 ± 0.055 26.668 ± 0.019 45.019 ± 0.055 29.789 ± 0.064 13.884 ± 0.007

In the monolithic dentures, AG and ag value between Group Up and Group Uc as well as between Group Um and Group Uc showed a statistically significant difference(One-way ANOVA, P<0.05). In the lower monolithic ones, ab, cd and ef value revealed a significant difference between Group Lp and Gorup Lm(One-way ANOVA, P<0.05).

V. Conclusion Dentures made using milling or 3D printers showed clinically very accurate reproducibility.