Abstract
Background: Alginate impression material is the irreversible hydrocolloid material that is widely used in dentistry. The contact time between alginate and gypsum cast could have a detrimental effect on the properties of the gypsum cast. The objective of this study is to evaluate the impact of various contact time intervals of Alginate impressions & type III dental stone on surface properties of stone cast. Materials and Methods: Time intervals tested were 1hour, 6 hours and 9 hours. Surface properties of stone cast evaluated were surface detail reproduction, hardness and roughness. Surface detail reproduction was determined using cylindrical brass test block in accordance with ISO 1563. Surface roughness was measured by profilometer and hardness was measured by Durometer (Shore D). Results: The detail reproduction showed significant difference (P<0.05), at 6 hr., and 9 hr. showed better results. While surface roughness significantly decreased (p<0.01) with prolonged contact time. However, surface hardness increased significantly (p<0.01) with increased contact time. Conclusions: Surface detail reproduction increased with increasing the contact time and this was noticed at (6, 9 hours). However, 1hour time interval showed decreased surface detailed reproduction. Roughness decreased when the contact time was increased between type III dental stone and alginate impression whereas, hardness was improved significantly with increasing contact time.
Highlights
In dentistry, methods of oral disease diagnosis and treatment are complemented by replicas of hard and soft tissue
Those replicas are known as study models, casts or dies They are used for studying some cases in dentistry; and all of these replicas are used in the dental practice
(1) there are several impression materials and procedures available for accurate impression making, irreversible hydrocolloids are among several impression materials that are commonly utilized in dental offices to produce stone casts [2]
Summary
Methods of oral disease diagnosis and treatment are complemented by replicas of hard and soft tissue Those replicas are known as study models, casts or dies They are used for studying some cases in dentistry; and all of these replicas are used in the dental practice. 9hr.) between alginate impression material and Type III dental stone on surface details reproduction, surface roughness and hardness of stone cast. The objective of this study is to evaluate the impact of various contact time intervals of Alginate impressions & type III dental stone on surface properties of stone cast. Roughness decreased when the contact time was increased between type III dental stone and alginate impression, whereas hardness was improved significantly with increasing contact time.
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