| JNDA Vol. 16 No. 1 (January - June 2016) | |
Dimensional accuracy of different impression materials and techniques commonly used in prosthodontics |
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| Dr. Minu Dhungana, Dr. Lochana Acharya, Dr. Sanjay Sah | |
Download Full Article  771KB |
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| Abstract | |
Introduction: The successful fabrication of indirect restorations largely depends on an accurate impression from which a replica of the intraoral structures can be precisely created. Therefore for accurate reproduction of the preparation margins in impression proper choice of impression material and technique is very important. Objective: The objective of this in vitro study was to evaluate and compare the dimensional accuracy of the cast obtained from different impression materials and techniques commonly used in fixed prosthodontics. Materials and Method: The impressions were made from a metallic master model made of stainless steel that simulated a tooth preparation for mandibular molar. The following impression materials were evaluated: polyvinyl siloxane in one-step dual viscosity technique (group 1), polyvinyl siloxane in two-step dual viscosity technique (group 2), laminated reversible/ irreversible hydrocolloid impression technique (group 3) and improved alginate (group 4). Dimensional changes (mm) were assessed between the master model and the stone model (type IV gypsum) at two reference points marked in the mesiodistal and buccolingual surfaces. The measurements of the master model and stone model were made with digital micrometer (accuracy of 0.001 mm) Result: The stone dies obtained with all the materials and techniques had significantly larger dimensions as compared to the master model (p<0.05). The lowest to highest deviation from the master model was found to be group 2, group 1, group 3 and highest deviation was shown by group 4. One way analysis of variance revealed no significant differences in dies obtained from the different groups of the impression. In comparison with the two techniques for the polyvinyl siloxane material two-step dual viscosity was more accurate than one-step dual viscosity technique. Conclusion: Different impression materials and techniques which are commonly available and used in fixed prosthodontics are accurate and can provide satisfactory clinical results when they are used in the correct method. |
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| Keywords | |
Alginate; dimensional accuracy; impression materials; laminated hydrocolloid technique, polyvinyl siloxane. |
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