Dev Shruti, Kar Aswini K, Garhnayak Mirna, Garhnayak Lokanath, Dhal Angurbala
Department of Prosthodontics, Kalinga Institute of Dental Sciences, KIIT University, Bhubaneswar, Odisha, India, Phone: +919437062100, e-mail:
Department of Prosthodontics, Kalinga Institute of Dental Sciences, KIIT University, Bhubaneswar, Odisha, India.
J Contemp Dent Pract. 2017 Oct 1;18(10):911-914. doi: 10.5005/jp-journals-10024-2148.
Alginate is a versatile, irreversible hydrocolloid impression material, which is cost-effective and forms an essential component in dental practice. For elevating the hardness of the cast models, hardeners are combined with stone. Hence, we planned the present study to evaluate the impact of altering the time of contact between alginate and stone after various interim periods.
The present study included the assessment of impact of time of contact between alginate and stone by the construction of 90 casts using a cylinder model. Two bisecting lines were marked and were named as y and y'. These lines were used for testing the dimensional stability. Using chemically cured acrylic resin, the construction of ten special trays was done. All the impression casts were randomly divided into two study groups, with 45 casts in each group-group I: control group, casts were removed after 60 minutes; group II: study group, casts were removed after 9 hours. A digital caliper was used for measuring the dimensional stability of the cast. All the data were collected and analyzed.
In the specimens of the control group (group I) and the study group (group II), the mean dimensions from y to y' were found to be 17.54 and 17.95 respectively. The mean reading of hardness in the control group and study group was found to be 0.59 and 0.20 respectively. In groups I and II, the number of specimens showing clarity of two lines (X and X") was 0 and 5 respectively.
There was no change in the dimensional stability of the dental stone model when the contact time was increased.
Within certain limits, the contact time between alginate and stone can be altered without significantly altering the properties of the cast.
藻酸盐是一种用途广泛、不可逆的水胶体印模材料，具有成本效益，是牙科实践中的重要组成部分。为了提高铸模的硬度，需将硬化剂与石膏混合使用。因此，我们开展了本研究，以评估在不同中间时间段后改变藻酸盐与石膏接触时间的影响。
本研究通过使用圆柱模型制作90个铸模，评估藻酸盐与石膏接触时间的影响。标记两条平分线，分别命名为y和y'。这些线用于测试尺寸稳定性。使用化学固化丙烯酸树脂制作了十个特殊托盘。所有印模铸模随机分为两个研究组，每组45个铸模——第一组：对照组，60分钟后取出铸模；第二组：研究组，9小时后取出铸模。使用数字卡尺测量铸模的尺寸稳定性。收集并分析所有数据。
在对照组（第一组）和研究组（第二组）的标本中，从y到y'的平均尺寸分别为17.54和17.95。对照组和研究组的平均硬度读数分别为0.59和0.20。在第一组和第二组中，显示两条线（X和X"）清晰的标本数量分别为0和5。
当接触时间增加时，牙科石膏模型的尺寸稳定性没有变化。
在一定范围内，可以改变藻酸盐与石膏的接触时间，而不会显著改变铸模的性能。
