Salloum A M
Department of Removable Prosthodontics, Faculty of Dental Medicine, Damascus University, Syria.
Eur J Prosthodont Restor Dent. 2013 Dec;21(4):182-6.
Although many factors that generate changes in OVD of complete dentures are known, no information is available in the dental literature regarding the effect of using high expansion dental stone (type V) on changes in OVD. This study therefore investigated the effect of a high expansion dental stone on the changes in OVD of complete dentures. A compression moulding technique was used to process twenty sets of simulated upper and lower dentures. Sample was equally divided into two groups: group of type III dental stone (DST III), and group of type V dental stone (DST V). In DST III, the lower, middle and upper parts of flask were filled with type III dental stone; In DST V, the procedure was the same as DST III except for the middle layer that was made of type V high expansion dental stone. Changes in OVD were measured before and after denture processing. A Shapiro-Wilk Normality Test was applied, and then collected data were analysed with t-test statistics for statistically significant differences at the 95% confidence level. The two groups revealed small but statistically significant increase in OVD as a result of processing. The increase in OVD was significantly less in DST V than in DST III. The use of high expansion dental stone can be recommended as investing material to reduce the increase in OVD that occurs after processing complete dentures.
尽管已知许多会导致全口义齿垂直距离（OVD）发生变化的因素，但牙科文献中尚无关于使用高膨胀牙科石膏（V型）对OVD变化影响的信息。因此，本研究调查了高膨胀牙科石膏对全口义齿OVD变化的影响。采用压缩成型技术制作了20副模拟上下颌义齿。样本平均分为两组：III型牙科石膏组（DST III）和V型牙科石膏组（DST V）。在DST III组中，型盒的下部、中部和上部填充III型牙科石膏；在DST V组中，除中间层由V型高膨胀牙科石膏制成外，操作过程与DST III组相同。在义齿制作前后测量OVD的变化。应用Shapiro-Wilk正态性检验，然后用t检验统计分析收集的数据，以确定在95%置信水平下的统计学显著差异。两组均显示由于制作过程，OVD有微小但具有统计学意义的增加。DST V组OVD的增加明显少于DST III组。可以推荐使用高膨胀牙科石膏作为包埋材料，以减少制作全口义齿后发生的OVD增加。
