A comparative analysis of the accuracy of implant master casts fabricated from two different transfer impression techniques

Abstract

Aim:This study evaluated and compared two impression techniques in terms of their dimensional accuracies to reproduce implant positions on working casts.Materials and Methods:A master model was designed to simulate a clinical situation. Impressions were made using four techniques: (1) Stock open tray (SOT) technique; (2) stock closed tray (SCT) technique; (3) custom open tray (COT) technique; and (3) custom closed tray (CCT) technique. Reference points on the hexagonal silhouette of the implant on master model and onto the analogs of the obtained master casts were compared after using the four impression techniques. Measurements were made using an optical microscope, capable of recording under 50x magnifications. The means and standard deviations of all the groups and subgroups were calculated and statically analyzed using analysis of variance (ANOVA) and Tukey's test.Results:The open tray impressions showed significantly less variation from the master model and all the techniques studied were comparable.Conclusion:All the techniques studied shown some distortion. COT showed the most accurate results of all the techniques.

Evaluation of the accuracy between splinting and non-splintingimpression techniques for multiple implants

“…3,9,12 Searching for decreasing the errors in the impression of multiple implants, the literature reports new techniques, such as the direct splinting impression, whose main goal is to link the transfer copings so that no distortion occurs inside the impression. 3,9,16 Currently, different methods are used to splint the copings: acrylic resin with dental floss, 2,[6][7][8]9,[17][18][19][20][21] premanufactured resin bar, 1,[3][4]25 plaster, 11 and composite resin. 2,8 The self-cured acrylic resin is the method of choice.…”

“…3 The use of customized trays show better results than that of conventional trays because of the uniform thickness of the first, which assured a uniform thickness of the impression material. 6 The literature reports sixteen studies using customized trays [1][2]4,[6][7]9,[11][12][18][19][20][21][22]25,26 and seven using conventional trays. 1,3,5,8,11,13,21 Furthermore, nine studies compared the direct with the indirect technique, and almost unanimously they reported better results with the open tray technique, 6,[11][12][15][16][17]24,27 except for one study that reported no statistically significant differences.…”

“…[1][2][3][4][5][7][8][9][10] Although a complete passive adjustment is practically impossible, 2 it is possible to avoid failure by observing the following clinical and laboratorial steps in detail: impression technique, impression tray type, characteristic of the impression material, plaster expansion, parallel or angulated implants, maxilla or mandible, implant connection, transfer coping type, implant and abutment alloy. 3,6,8,[11][12] The impression must reproduce the anatomic details precisely and establish the transfer correctly.…”

“…Some studies reported the best impression material, [1][2][3][4][5][7][8]10,[12][13][14][15][16][17][18][19][20][21][22][23][24] the best technique (direct open tray vs indirect close tray), [5][6]11,[15][16][17][22][23][24] and the best tray. 2,4,[6][7]9,[11][12]14,[18][19][20][21][22][25][26][27] However, the literature lacks consensus on the best transfer technique, with or without splitting of transfer copings, 23,26,28 . By analyzing a systematic review from 1990 to 2012, 30 studies observed the effect of the splinting, 13 (> 43%) found the best splinting technique, and other 13 (> 43%)...…”

“…4,6,10,18,20,21 On the other hand, other in vitro studies point out that either splinting or non-splinting transfer coping techniques are statistically similar. 5,9,12,17,19,26 This study aimed to evaluate transfer coping impression technique with splinting comparing with transfer coping impression technique without splinting, by observing some possible interferences such as: the resin type used for splinting, [1][2][3][4][5][6][7][8][9]11,13,15,[17][18][19]21,26,29,30 customization of the splinting bar, 14,17 and control of resin polymerization shrinkage.…”