Journal of the korean academy of Pediatric Dentistry (대한소아치과학회지)

Korean Academy of Pediatric Dentistry (대한소아치과학회)
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Fracture Strength and Translucency of CAD/CAM Zirconia Crown for Primary Anterior Tooth

CAD/CAM으로 제작한 유전치 지르코니아 전장관의 두께에 따른 파절강도와 반투명도 비교

  • Ong, Seung-Hwan (Department of Pediatric Dentistry, College of Dentistry, Dankook University) ;
  • Kim, Jongsoo (Department of Pediatric Dentistry, College of Dentistry, Dankook University) ;
  • Kim, Jongbin (Department of Pediatric Dentistry, College of Dentistry, Dankook University) ;
  • Shin, Jisun (Department of Pediatric Dentistry, College of Dentistry, Dankook University) ;
  • Yoo, Seunghoon (Department of Pediatric Dentistry, College of Dentistry, Dankook University)
  • 옹승환 (단국대학교 치과대학 소아치과학교실) ;
  • 김종수 (단국대학교 치과대학 소아치과학교실) ;
  • 김종빈 (단국대학교 치과대학 소아치과학교실) ;
  • 신지선 (단국대학교 치과대학 소아치과학교실) ;
  • 유승훈 (단국대학교 치과대학 소아치과학교실)
  • Received : 2019.12.19
  • Accepted : 2020.02.03
  • Published : 2020.05.31
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Abstract

The purpose of this study is to evaluate the validity of primary anterior zirconia crown made with Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) technology by analyzing fracture strength and translucency parameter. Zirconia crown was designed with CAD software, using 3D scanned data of #61 tooth model. Crown fabrication was performed with CAM machine using zirconia block. Zirconia crowns were divided into 3 groups according to thickness(0.3, 0.5, and 0.7 mm), and fracture strength was compared with 1.0 mm thickness of resin strip crown. The compressive force was applied with universal testing machine at 30° along the incisal edge at increments of 1 mm/min. For translucency evaluation, 0.3, 0.5, and 0.7 mm thickness of zirconia specimens were fabricated and translucency was measured with spectrophotometer. Among zirconia groups, there was a significant increase in fracture strength as thickness increased (p < 0.05). The fracture strength of zirconia crown was significantly higher than resin strip crown in all groups (p < 0.05). Translucency parameter was highest in 0.3 mm group, and significantly decreased as thickness increased to 0.5 and 0.7 mm (p < 0.05). Thin primary anterior zirconia crown can be designed and fabricated according to individual needs by using CAD/CAM. Restoration with thin crown would reduce the amount of tooth reduction, risk of pulp exposure, and make more esthetic restoration possible.

이 연구의 목적은 파절강도와 반투명도 측정을 통해 Computer Aided Design/Computer Aided Manufacturing (CAD/CAM)으로 제작한 유전치 지르코니아 전장관의 임상적 적용 가능성을 확인하는 것이다. 기성 유전치 모형 중 #61을 스캔하여 얻은 3차원 형상 데이터로 CAD 디자인 프로그램을 이용하여 전장관을 디자인하고, 지르코니아 블록으로 CAM 밀링 기계를 이용하여 전장관을 제작하였다. 지르코니아 전장관은 두께에 따라 0.3, 0.5, 그리고 0.7 mm의 3군으로 나누어 1.0 mm 두께의 레진 전장관과 파절강도를 비교하였다. 파절강도는 만능시험기를 이용하여 30° 각도에서 1 mm/min 속도로 절단면에 하중을 가하여 측정하였다. 반투명도는 가로와 세로가 7.0 mm, 그리고 두께가 각각 0.3, 0.5, 0.7 mm 인 사각형 지르코니아 시편을 제작하여 분광측색장치로 측정하였다. 파절강도 측정 결과 지르코니아 전장관은 두께가 증가할수록 파절강도가 높아졌으며 모든 두께의 지르코니아 군에서 대조군인 레진 전장관보다 파절강도가 높았다(p < 0.05). 반투명도는 0.3 mm 군에서 가장 높았으며 0.5, 0.7 mm로 두께가 증가할수록 감소하였다(p < 0.05). CAD/CAM으로 제작한 지르코니아 전장관은 개별 치아에 맞추어 얇게 디자인 및 제작 가능하며, 얇은 전장관을 이용한 수복은 임상적으로 치아 삭제량과 치수노출 위험성 감소 뿐만 아니라, 더 심미적인 수복을 가능하게 해줄 것이다.

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