Evaluation of accuracy of implant impressions : a comparative analysis of the impression techniques, impression materials and the inter-implant span
MetadataShow full item record
Purpose: The aim of this study was to evaluate and compare the accuracy of implant casts made by differrent impression techniques and materials and to study the association between the inter-implant distance and the positional distortion of the implants. Method and material: A metal master model was duplicated from a clinical complete edentulous maxillary stone cast with four implant analogs placed in position of teeth # 3, 5, 11, 14 to serve as abutments for a short and a long FPDs. Using two impression materials (polyether and polyvinyl siloxane) and three impression techniques (Indirect, Direct and Direct Splinted), a total of sixty impressions were made of the master model. For the Direct Splint group, prefabricated acrylic resin bars were used to splint the impression copings. Coordinate Measuring Machine (FaroArm) with an accuracy of 0.025 mm was used to measure the relative position of implants on each cast on three axes ([delta]X,[delta]Y, and [delta]Z). The difference in global distortion inter-implant distances ([delta]R) on each cast and the master model was calculated. The Kruskal-Wallis test was selected for the analysis of the data followed by the Mann-Whitney (P [less than or equal to] 0.05 with confidence level of 95%). Results: The overall measured distortion of the inter-implant distance was [delta]R=0.11mm, [delta]X=0.05mm, [delta]Y=0.11mm, and [delta]Z=0.11mm. Irrespective of impression technique or material used, the longer inter-implant span’s distortion ([delta]R=0.14±0.04mm) was significantly more than the short span’s distortion ([delta]R=0.09±0.04mm) (P=0.05). Irrespective of impression material, the impression techniques produced comparable accuracy. Irrespective of impression techniques, polyether with mean distortion of ([delta]R=0.10±0.05mm) resulted in significantly better accuracy than poly vinyl siloxane with mean distortion of ([delta]R=0.13±0.04mm) (P=0.05).The results of this study demonstrated an interaction between the three tested factors (Impression technique, material and inter-implant distance).In some cases, the significance of the differences in accuracy was affected by this interaction. Conclusion: All three impression techniques and two impression materials studied showed some degree of distortion in transferring implant positions. The distance between two implants had a decisive influence on the accuracy of the transfer of the implant positions. The longer the inter-implant distance, more distortion of the impression occurred. Splinting impression copings results in statistically significant impression accuracy only if used in combination with polyether for impression of long inter-implant span. Some specific combinations of impression techniques and materials had a significant influence on the accuracy of the impression but considering the amount of distortion differences between the experimental groups (about 0.04mm or less), and the accuracy of the measuring device (0.025mm), the differences calculated for most variables may be too small for significant clinical impact.
Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2009 (Department of Restorative Science and Biomaterial).Includes bibliographic references: leaves 88-94.
RightsThis work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.
Showing items related by title, author, creator and subject.
Accuracy of digital impressions, master casts, and final restorations achieved from five different digital impression systems Ali, Ala Omar (Boston University, 2015)The purpose of this study was to test: the accuracy of digital impressions, master models obtained from different digital and conventional impression systems, and the accuracy of marginal and internal adaptations of the ...