교합면에 형성된 offset groove가 금관 및 지대치의 응력 발생에 미치는 영향 = The Effect of Occlusal Offset Groove on The Stress Distribution in The Cast Gold Crown and Autment Tooth

다국어 초록 (Multilingual Abstract)

When an offset groove is formed on the occlusal surface of abutment tooth, resistance to movement and deformation of the cast crown will increase because of the increase in the metal thickness and anchoraging effect provided by the offset
In an attempt to increase the resistance of the cast crown, a tooth preparation method with an occlusal offset of 1.2㎜ width, 2.0㎜ length and two different depths of 0.5㎜ or 1.0㎜ was newly designed by authors.
20kg load was applied', vertically on the occlusal surface, 45˚ obliquely on the central fossa area and 45˚ obliquely on the buccal cusp surface of buccal cusp tip.
To evaluate the possible clinical use of this new method, von Mises maximum stress values developed in the crown and Maximum Principal values developed in the abutment tooth, which were obtained with two dimensional finite element analysis, were compared with that in the conventional method which had no occlusal offset groove.
The obtained results were as follows,
1. The stress distribution effect of the occlusal offset varied according to the direction of the forces applied.
2. The depth of occlusal groove seemed to have no significant influence on the stress distribution effect.
3. When a vertically directed forces were applied on the buccal cusp tip and on the central fossa area of the occlusal surface, von Mises maximum stress values developed in the offset formed gold crown and Maximum Principal stress values in the offset grooved tooth were both decreased and the amount of decreased value in the gold crown was much more noticeable than that in the tooth.
4. When an obliquely directed forces were applied on the central fossa area of occlusal surface, regardless of offset forming, von Mises stress values developed in the crown and Maximum Principal stress values in the tooth were almost identical in all cases.
5. When an obliquely directed forces were applied on the buccal surface of buccal cusp tip area, von Mises stress values in the offset formed crown were somewhat decreased, while Maximum Principal values in the offset grooved tooth were somewhat increased.
6. Considering the occlusal scheme in the natural dentition, occlusal offset seemed to have an advantageous effect on the stress distribution, both in the cast gold crown and in the abutment tooth.