Samet Nachum, Shohat Michal, Livny Alon, Weiss Ervin I
Harvard School of Dental Medicine, Boston, MA, USA.
J Prosthet Dent. 2005 Aug;94(2):112-7. doi: 10.1016/j.prosdent.2005.05.002.
Providing the dental laboratory with an accurate replication of the hard and soft tissue of a patient is important. Therefore, it is essential to examine whether clinicians critically evaluate impressions routinely before sending them to the laboratory.
This study evaluated the quality of impressions sent to commercial laboratories for the fabrication of fixed partial dentures (FPD) by describing the frequency of clinically detectable errors and by analyzing correlations between the various factors involved.
A total of 193 FPD impressions were evaluated, immediately after arrival at 11 dental laboratories, by 3 calibrated examiners. The impression technique and material used, tray type, and number of prepared units were recorded for each impression. Data relating to errors and faults, including defects in material polymerization, retention to tray, tissue contact by tray, crucial areas beyond tray borders, heavy-bodied material exposure through the wash material (for double-step impressions), inadequate union of materials, retraction cords embedded in impressions, and air bubbles, voids, or tears along the margin were also documented. The data were analyzed with the Pearson chi-square test (alpha = .05).
Of the impressions, 89.1% had 1 or more observable errors. Significant correlations were found between material type and voids or tears at the finish line (Rv = 0.17, P < .025) and between material type and polymerization problems (Rv = 0.223, P < .004).
Within the limitations of this study, impressions made with polyethers had the most detectable errors, followed by condensation-type silicones. The high frequency of detectable errors found in impressions sent for FPD fabrication is of concern.
为牙科实验室提供患者软硬组织的精确复制品很重要。因此，至关重要的是检查临床医生在将印模常规性地送往实验室之前是否会严格评估印模。
本研究通过描述临床可检测到的错误频率并分析所涉及的各种因素之间的相关性，评估送往商业实验室用于制作固定局部义齿（FPD）的印模质量。
3名经过校准的检查人员在11家牙科实验室收到193个FPD印模后立即对其进行评估。记录每个印模所使用的印模技术和材料、托盘类型以及预备单位数量。还记录了与错误和缺陷相关的数据，包括材料聚合缺陷、与托盘的固位、托盘与组织的接触、托盘边缘以外的关键区域、通过冲洗材料暴露的高稠度材料（用于双重印模）、材料结合不充分、印模中嵌入的收缩线以及边缘处的气泡、空隙或撕裂。数据采用Pearson卡方检验进行分析（α = 0.05）。
在这些印模中，89.1%有1个或更多可观察到的错误。发现材料类型与终印线处的空隙或撕裂之间存在显著相关性（Rv = 0.17，P < 0.025），以及材料类型与聚合问题之间存在显著相关性（Rv = 0.223，P < 0.004）。
在本研究的局限性范围内，聚醚类印模的可检测错误最多，其次是缩合型硅橡胶印模。用于FPD制作的印模中发现的可检测错误频率令人担忧。
