Luk H W, Darvell B W
Dental Technology Unit, University of Hong Kong, Faculty of Dentistry, Prince Philip Dental Hospital, Hong Kong.
J Dent. 1997 Mar;25(2):153-60. doi: 10.1016/s0300-5712(96)00011-5.
The high-temperature strength behaviour of dental phosphate-bonded investments is not clearly understood. The present purpose was to determine their variation in strength with temperature and to seek explanations for that variation.
The clamped-edge disc-rupture test was used in a sequential testing protocol, with a variable casting metal mass, to determine the effect of burnout temperature (ranging from 400 to 1100 degrees C) on the strength of six phosphate-bonded investments.
The strength of phosphate-bonded investment is temperature sensitive, generally showing a distinct minimum in the tested temperature range. Low temperature strength gives little information about high temperature behaviour. The variation of strength with temperature seems amenable to explanation in terms of investment composition.
Since strength varies greatly with temperature and brand, the inconsistency of previous results is explained. On the other hand, low-temperature strength is no guide for the high-temperature strength, so that information on both the room and the service temperature strength is required. Inversion of silica at high temperature may decrease the strength of phosphate-bonded investments.
牙科磷酸盐结合包埋材料的高温强度行为尚未得到明确了解。本研究的目的是确定其强度随温度的变化情况，并探寻这种变化的原因。
采用夹边圆盘断裂试验，按照顺序测试方案，使用不同质量的铸造金属，以确定焙烧温度（400至1100摄氏度）对六种磷酸盐结合包埋材料强度的影响。
磷酸盐结合包埋材料的强度对温度敏感，在测试温度范围内通常呈现明显的最小值。低温强度几乎无法提供有关高温行为的信息。强度随温度的变化似乎可以从包埋材料的成分方面进行解释。
由于强度随温度和品牌的变化很大，解释了先前结果不一致的原因。另一方面，低温强度不能作为高温强度的参考，因此需要了解室温强度和使用温度强度的信息。高温下二氧化硅的转化可能会降低磷酸盐结合包埋材料的强度。
