The Journal of Korean Academy of Prosthodontics (대한치과보철학회지)

The Korean Academy of Prosthodonitics (대한치과보철학회)
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EFFECTS OF AGING AND THERMAL CYCLING ON THE BIAXIAL FLEXURE STRENGTH OF VENEERING RESIN COMPOSITES FOR CROWN

시효처리와 thermal cycling이 치관전장용 복합레진의 2축굽힘강도에 미치는 영향

  • Jeong, Gwan-Ho (Department of Prosthetics Dentistry, Institute of Oral Bioscience, College of Dentistry, Chonbuk National University) ;
  • Ha, Il-Soo (Department of Prosthetics Dentistry, Institute of Oral Bioscience, College of Dentistry, Chonbuk National University) ;
  • Song, Kwang-Yeob (Department of Prosthetics Dentistry, Institute of Oral Bioscience, College of Dentistry, Chonbuk National University)
  • 정관호 (전북대학교 치과대학 보철학교실, 구강생체과학 연구소) ;
  • 하일수 (전북대학교 치과대학 보철학교실, 구강생체과학 연구소) ;
  • 송광엽 (전북대학교 치과대학 보철학교실, 구강생체과학 연구소)
  • Published : 1999.10.01
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Abstract

This study was performed to evaluate the effect of aging and thermal cycling on the biaxial flexure strength of low commercially available veneering resin composites for crown(Dentacolor : DC, Artglass : AG, Esternia : ET and Targis : TG). Disc specimens were fabricated in a teflon mold giving 12mm in diameter and 1mm in thickness. All samples were divided into 4 groups. Group 1 was dried in a dessicator at $25^{\circ}C$ for 30 days. Group 2 was immersed in distilled water at $37^{\circ}C$ for 30 days. Group 3 was immersed in distilled water at $65^{\circ}C$ for 30 days. Group 4 was subjected to 10,000 thermal cycles between $5^{\circ}C\;and\;55^{\circ}C$, and the immersion time in each bath was 15 seconds per cycle. Biaxial flexure test was conducted using the ball-on-three-ball method at the cross head speed of 0.5mm/min and fracture surfaces were observed with scanning electoron microscope. The results obtained were summarized as follows; 1. Weibull modulus values, except for the AG group, decreased after thermal cycling treatment. 2. Biaxial flexure strength values of aging group at $37^{\circ}C$ were the lowest in all sample groups. Except for the DC group, strength values were significantly decreased for the drying group. 3. After thermal cycling test, the highest value of biaxial flexure strength of 188.8 MPa was observed in the ET group and the lowest value of 73.2 MPa was observed in the DC group. The strength values showed the significant differences in each group (p<0.05). 4. Observation of surfaces after thermal cycling test revealed the ditching in the part of surrounding large fillers.

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