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2.Evaluation of Defects in Surface Detail of 2 Phase One Step Versus 2 Phase Two Step Impression Techniques: An In Vitro Study
Khalid Yaqub, Abdul Mueed Zaigham, Hamza Talat, Hamza Ahmed Sahaf, Daniyal Naeem Dar and Muhammad Afzal
ABSTRACT
Objective: To compare frequency of defects in surface detail of 2 phase one step versus 2 phase two step impression techniques.
Study Design: Randomized control trial study
Place and Duration of Study: This study was conducted at the Department of Prosthodontics, Institute of Dentistry, CMH Lahore Medical College from 14-5-2018 to 14-11-2018.
Materials and Methods: A total of 618 impressions were taken on a stainless steel abutment which were prepared and fabricated according to American Standards Institute- American Dental Association specifications. This model was incorporated in auto polymerizing resin and fixed onto a base. The auto polymerizing resin was then modeled to allow reproducible positioning of impression trays on the model. All impressions were made in stock perforated trays. The Impressions were divided into two equal groups i.e. Group A (Two phase one step) and Group B (Two phase two step). The impressions were then removed from master model. The Number of defects produced in both groups were evaluated and counted by an examiner trained in standardized technique for recognition and classification of surface defects. They were further confirmed by taking pictures of individual impressions.
Results: The defects in surface were noted in 54.5% impressions. Out of these 337 impressions Type I (group A) classification was found in 273(81%) impressions and type II (group B) classification was noted 19% in impressions. In group-A the defect in surface noted in 59.9% impressions and in group B the defect in surface noted in 49.2% impressions (p-value=0.008).
Conclusion: This present study showed that 2 phase two step impression techniques showed significantly lower defect rate than to 2 phase one step technique in evaluation of defects in surface.
Key Words: Impression Techniques, Two Step, One Step, Defect, Surface