Microcracks in dental porcelain and their behavior during multiple firing
Microcracks in dental porcelain and their behavior during multiple firing
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DOI：
10.1177/00220345960750070801
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发表时间：
1996-07-01
影响因子：
7.6
通讯作者：
Williams, AL
中科院分区：
文献类型：
--
作者：
Mackert, JR;Williams, AL
牙科陶瓷依赖于高热膨胀矿物白榴石，以提高其整体热膨胀的水平，与牙科PFM合金兼容。在烤瓷制造过程中，当冷却时，这些白榴石颗粒周围形成的微裂纹是烤瓷熔附金属冠和桥制造过程中大块瓷热膨胀变化的潜在来源。本研究的目的是确定商业牙科陶瓷的多次烧制是否会产生微裂纹密度的变化。制造了六种商业瓷器和Weinstein专利的“1号组件”的样品，并进行了1、2、4、8和16次烧制。通过定量体视学确定微裂纹密度，从而用测试网格计算微裂纹的交叉点。微裂纹数据进行线性回归分析和方差分析。六个瓷中的四个和1号部件熔块的微裂纹密度不受烧制次数的显著影响（p > 0.05）。一个瓷显示出微裂纹密度与多次烧制之间的弱但高度显著的正相关性（r（2）= 0.24，p = 0.0003），而其余瓷显示出微裂纹密度与多次烧制之间的弱但统计学显著的负相关性（r（2）= 0.15，p = 0.006）。本研究的结果表明，即使是陶瓷表现出可测量的变化，微裂纹密度作为一个功能的多次烧制，微裂纹密度的增加或减少的幅度后，几次烧制是足够小的，导致只有可忽略不计的变化，在瓷体热膨胀。
Dental porcelains rely on the high-thermal-expansion mineral leucite to elevate their bulk thermal expansion to levels compatible with dental PFM alloys. The microcracks that form around these leucite particles when cooled during porcelain manufacture are a potential source of change in bulk porcelain thermal expansion during fabrication of porcelain-fused-to-metal crowns and bridges. The purpose of the present study was to determine whether multiple firings of commercial dental porcelains could produce changes in microcrack density. Specimens of six commercial porcelains and the ''Component No. 1'' of the Weinstein patent were fabricated and subjected to 1, 2, 4, 8, and 16 firings. The microcrack densities were determined by quantitative stereology, whereby intersections of microcracks were counted with a test grid. The microcrack data were subjected to linear regression analysis and analysis of variance. The microcrack densities of four of the six porcelains and the Component No. 1 frit were not significantly affected by the number of firings (p > 0.05). One porcelain exhibited a weak but highly significant positive correlation between microcrack density and multiple firings (r(2) = 0.24, p = 0.0003), while the remaining porcelain exhibited a weak but statistically significant negative correlation between microcrack density and multiple firings (r(2) = 0.15, p = 0.006). The results of this study indicate that even for porcelains that exhibit a measurable change in microcrack density as a function of multiple firings, the magnitude of the increase or decrease in microcrack density after several firings is sufficiently small to cause only negligible shifts in porcelain bulk thermal expansion.