Assessment of impression quality perception by dental students and teachers

Method: Students of 5^th year of School of Dental Medicine UNIZG made conventional impressions for working models in various clinical cases. Ten impressions were made (polyether, medium consistency) and photographed in standardized conditions. A questionnaire was designed to evaluate on a 1-5 scale (1- not acceptable, 5- excellent) the overall quality of impression, the need to retake it, and to evaluate the impression by specific parameters including the choice of impression tray, positioning, detail reproduction and surface quality. The questionnaires were filled by 4^th and 5^th year dental students (66 overall) and 6 clinical teachers. 

Result: Mann-Whitney U test demonstrated significant differences between 4^th and 5^th year students for most parameters investigated, with 5^th year students being significantly more critical (p<0.05), which is expected regarding significantly more experience in 5^th year students (χ2 = 46,390; ss= 2; P<0,001; Cramer V = 0,845). Significant differences were determined between the overall impression quality grade and average grades for specific parameters only for 4^th year students (Wilcoxon p=0.002), while the 5^th year students and teachers were significantly more consistent in their grading (p=0,354). Spearmann’s rho coefficient demonstrated significant negative correlation between the impression-taking experience and average overall impression quality assessment (p<0.05). No significant differences were determined between the 5^th year students and teachers.

Conclusion: Impression quality perception depends mostly on experience. Students with more experience quickly acquire and implement quality control parameters.