Pressure Produced on the Residual Maxillary Alveolar Ridge by Different Impression Materials and Tray Design: An In Vivo Study

Abstract

Increased ridge resorption may occur due to inappropriate pressure applied during final impression making phase of complete denture fabrication. This study was done to evaluate the pressure applied on the residual ridge while making impressions with two tray designs (with and without spacer) using, zinc oxide eugenol and light body polyvinyl siloxane impression material. Five edentulous subjects were randomly selected. For each of the five subjects four maxillary final impressions were made and were labelled as, Group A-Impression made with tray without spacer using zinc oxide eugenol impression, Group B-Impression made with tray with spacer using zinc oxide eugenol impression material, Group C-Impression made with tray without spacer using light body polyvinyl siloxane impression material, Group D-Impression made with tray with spacer using light body polyvinyl siloxane impression material. During the impression procedure a closed hydraulic system was used to remotely measure the pressures produced in three areas. The pressure produced were calibrated according to the micro strain record. Statistical comparisons of readings were done using t test and ANOVA. The acquired data revealed that ZOE produced an average pressures value of 26.534 and 72.05 microstrain, while light body PVS produced 11.430 and 37.584 microstrain value with and without spacer respectively. Significantly high values were recorded on the vault of the palate when using trays without spacer. The use of light body polyvinyl siloxane and zinc oxide eugenol impression material showed insignificant difference. Within the limitations of this study, tray design has a significantly effected on the pressures produced, while the impression materials does not have any significant difference.

Displacement of Simulated Flabby Tissue by Different Tray Designs and Impression Materials

“…When the tray design was kept constant, there were no significant differences in tissue displacement between the different impression materials used across all the measuring points, except the anterior and posterior parts of the flabby tissues at the 8‐mm sagittal sections bilaterally. This is similar to the results of Reddy et al's in vivo study, reporting that in maxillary edentulous patients the pressures recorded when impressions were made with ZOE paste and light‐body type of VPS were similar; however, the studies by Frank and Masri et al suggest that the impression material used contributed to differences in pressure when making maxillary edentulous impressions. These findings indicated that the viscosity of the impression material is directly related to the amount of pressure produced.…”

“…The null hypothesis was rejected, because displacement of the flabby tissue was significantly affected by the tray designs and impression materials. Previous studies evaluated the factors that control tissue displacement caused by the force exerted while making impressions indirectly by assessing the pressure generated when making an impression rather than directly by assessing the amount of tissue displacement . Moreover, these studies only evaluated the displacement of the normal denture‐bearing areas, and could not explain or contribute to the understanding of the displacement of flabby tissues.…”

“…The displacement of tissues during impressions can be reduced by controlling the force exerted by adjusting factors such as tray design, impression material, and seating velocity . A variety of tray designs have been introduced to minimize the distortion and displacement of the flabby tissue.…”

Técnicas e materiais de impressão em prótese total lecionados em pós-graduações ibéricas

“…17 O seu uso nestas moldeiras leva a uma redução da pressão exercida sobre as cristas alveolares. 27 Em relação à colocação de stops e orifícios de escape nas moldeiras individuais, a maioria das pós -graduações Ibéricas não realizava nenhum dos dois. Porém, em Portugal, 50% realizava orifícios de escape.…”

Custom double tray for a special impression technique for flabby maxillary residual ridge: Case report

“…The tray design can be altered either with spacers or perforating impression trays, scraping impression trays, using open trays with the window technique, and using detachable trays. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Trays with additional spacers and holes or trays that open near the flabby ridge area reduce tissue displacement. 18 Open window trays yield the smallest magnitude of displacement.…”