Effect of techniques, trays and materials on accuracy of impressions clinically made

Abstract

Introduction Making accurate and dimensionally stable impressions to duplicate oral conditions and tooth morphology is an essential step of prosthetic dentistry for fabricating well-fitted indirect restorations and, consequently, ensure the longevity and success of the treatment. Several authors describe pros and cons of different impression techniques, although there is no unanimity among them about the best one. Objective This study evaluated casts’ accuracy made by different impression techniques, trays and materials. Material and method 10 patients were selected and 20 impressions from teeth #13 to #16 were performed using single-step (SS) and two-step techniques, made with metal stock and customized acrylic resin partial trays, vinyl polysiloxane and condensation silicone rubbers. Type IV gypsum was used to pour the casts. Three photographs of each patient (baseline), as their respective gypsum casts, were taken, measured in their interested buccal surface area. Comparisons of area values among experimental groups and baseline were performed. Data showed adherence to normal curve, being submitted to 3-way ANOVA/Bonferroni test (α=.05). Result Technique produced significant differences (P=0.02). SS technique was more accurate than BUR one (P=0.003; 95=1.22 to 5.98), but both resulted in similar casts to PVC, MOV and NR techniques, which were similar to each other (P>0.05). Conclusion SS technique showed the closest absolute values to baseline.

Effect of Water Type Used in Mixing the Alginate on the Final Stone Cast of Removable Partial Dentures

“…The results showed, as in Table (1), that there were changes in the linear dimensions in all groups, regardless of the type of water used, but unevenly between them without the presence of statistically signi cant differences, where the value of the signi cance level was greater than 0.05 in most of the measurements, except for the front vertical linear dimension where The signi cance level value was less than 0.05, meaning that there are statistically signi cant differences in all groups Whatever type of water is used. To nd out which groups contain the largest values of the differences, the Bonferroni method was used, which showed that the changes in the tap water group were the largest, where the p-value was less than 0.05, that is, at the 95% con dence level, there are statistically signi cant differences, as in table (2).…”

“…Recording an accurate impression is one of the most important steps in prosthetic dentistry for a successful denture, Therefore, it is important to fully understand its characteristics and the factors that in uence it to avoid possible complications 1,2,3,4 . Alginate was developed as an alternative to agar during World War II, and is still the rst choice for primary impressions of edentulous patients also can be used to record diagnostic impressions of orthodontic treatment, or to obtain the nal gypsum cast in cases of partially edentulous patients where obtaining accurate nal impression is an important rst step For a series of subsequent steps to achieve a good oral prosthetics 5,6,7,8 .…”

A Comparative Study to Evaluate the Accuracy of Various Spacer Thickness for Polyvinyl Siloxane Putty-wash Impression Techniques: An In Vitro Study

“… 24 , 25 Moreover, the accuracy of the two-step technique using uniform wash space 11 , 20 was more than the one-step technique. 28 , 29 , 41 Another disadvantage of the one-step technique is that the margins may be recorded in putty rather than light body because of the lower viscosity of the latter, which can result in inaccurate dies. 9 , 20…”