Comparison and Evaluation of Marginal Accuracy of Provisional Restoration by 3 Different Materials In vitro Study

Overview: Provisional Restoration plays a vital role in the long term Success of fixed partial restorations. A provisional restoration is a transitional restoration that provides protection, stabilization and function before Fabrication of the definitive prosthesis. A poorly adapted provisional restoration encourages plaque accumulation which can lead to periodontal conditions ranging from gingival Inflammation to periodontal support breakdown, this being especially true in cases where finish line margins are placed equigingivally or subgingivally. Aim of this in vitro study to compare the vertical marginal discrepancy of provisional restorations fabricated using light polymerized composite resin by direct technique. Materials and methods: Ivorine teeth (mandibular right and left 1st molar) were attached to the Typodont. Putty index was prepared Putty for each Ivorine tooth and prepared for a full crown restoration with a 1mm shoulder finish line and a uniform height of 6 mm of all the axial surfaces. After tooth preparation, impression was made with heavy body and light body using putty wash technique. Impression was immediately poured with die stone. Altogether sample size was 48. Provisional crowns fabricated using direct technique and cemented using Freegenol luting cement. They were divided into 3 groups, i.e. sixteen for each material. Die hardener was applied to the remaining part of the stone dies to prevent distortion of the die stone during aging process of the specimen. Each group was further divided into 8 depending on the type of aging process the specimens were subjected to: Pepsi, Tea and Arabian coffee and soaked for 54 hours. After immersion, the specimens were washed in distilled water, dried with filter paper, and subjected to marginal accuracy by Stereo microscope. Data obtained in the present study was subjected to statistical analysis using one-way ANOVA and inter group comparison was done with PostHoc Bonferroni’s correction SPSS Version 21. Results: Comparison of the buccal marginal discrepancies in the 3 materials used for temporary crowns using ANOVA showed significant changes when dipped in the 3 beverages. Significant buccal and lingual marginal discrepancy of all 3 temporary crowns was observed when immersed in tea compared to coffee and Pepsi as well as coffee with Pepsi by Post-Hoc Bonferroni’s correlation. Conclusion: Within the limitations of this study, it was concluded that, all the three temporary crowns fabricated from different materials showed significant marginal discrepancy when dipped in three different beverages

Comparison of marginal accuracy of castings fabricated by conventional casting technique and accelerated casting technique: An in vitro study.

Background: Conventional casting technique is time consuming when compared to accelerated casting technique. In this study, marginal accuracy of castings fabricated using accelerated and conventional casting technique was compared. Materials and Methods: 20 wax patterns were fabricated and the marginal discrepancy between the die and patterns were measured using Optical stereomicroscope. Ten wax patterns were used for Conventional casting and the rest for Accelerated casting. A Nickel-Chromium alloy was used for the casting. The castings were measured for marginal discrepancies and compared. Results: Castings fabricated using Conventional casting technique showed less vertical marginal discrepancy than the castings fabricated by Accelerated casting technique. The values were statistically highly significant. Conclusion: Conventional casting technique produced better marginal accuracy when compared to Accelerated casting. The vertical marginal discrepancy produced by the Accelerated casting technique was well within the maximum clinical tolerance limits. Clinical Implication: Accelerated casting technique can be used to save lab time to fabricate clinical crowns with acceptable vertical marginal discrepancy.

Marginal Fidelity And Fracture Strength Of Ips Empress 2(R) Ceramic Crowns According To Different Cement Types / 대한치과보철학회지

There has been increasing use of IPS Empress 2(R)owing to easy fabrication method, high esthetics similar to natural teeth, good marginal accuracy, and sufficient fracture strength. However, in clinical application, although a luting agent and the tooth cementation bonding procedure influence the marginal accuracy and fracture strength restoration, there has been a controversy in the selection of proper luting agent. This study was to measure the marginal fidelites and fracture strength of IPS Empress 2(R) crowns according to three cement types, Protec cem(R), Variolink II(R) and Panavia 21(R). After construction of 12 experimental dies for each group, IPS Empress 2(R)crowns were fabricated and luted the metal master die prepartion of the maxillary right premolar. Marginal gaps before cementation and after cementation were measured. Buccal incline on the functional cusp of specimens were loaded until the catastrophic failure and fracture strength was measured. The results of this study were as follows: 1. The range of gap was 34.04 +/- 4.84 micro meter before cementation and 37.88 +/- 5.00 micro meter after cementation, which showed significant difference by paired t-test (p0.05). 2. The difference in the results from marginal accuracy according to three cement types proved that The Variolink II(R) cement group had the least gap, 35.43 +/- 5.03 micro meter, and showed superior marginal accuracy while there existed statistic significance in Protec cem(R) cement group, 39.06 +/- 4.41 micro meter or Panavia 21(R)cement group, 39.16 +/- 4.39 micro meter by two-way ANOVA test and multiple range test (p<0.05). 3. The difference in the results from fractures strength testing according to three cement type groups proved to be statistically significant (p<0.05). The Variolink II(R) cement group shows the highest fracture strength of 1257.33 +/- 226.77 N, Panavia 21(R)cement group has 1098.08 +/- 138.45 N, and Protec cem(R) cement group represents the lowest fracture strength of 926.75 +/- 115.75 N. 4. Three different cement groups of different components showed acceptable marginal fidelity and fracture strength. It is concluded that IPS Empress 2(R)crowns luted using Variolink II(R) cement group had stronger fracture strength and smaller marginal gap than the other cement groups. Although Variolink II(R) resin cement seemed acceptable to clinical applications in IPS Empress 2(R)system, the IPS Empress 2(R)system still requires long-term research due to the lack of data in clinical applications

Marginal accuracy and fracture strength of Targis/Vectris Crowns prepared with different preparation designs / 대한치과보철학회지

STATEMENT OF PROBLEM: Targis/Vectris restorations provide excellent esthetics. Marginal accuracy is significantly influenced by the preparation design. There were no studies to examine the effect of preparation design on the marginal discrepancy and fracture strength of Targis/Vectris crowns. PURPOSE: This study evaluated the marginal accuracy before and after cementation, and the fracture strength of FRC/Ceromer(Targis/Vectris) crowns according to different preparation design. MATERIAL AND METHOD: Three metal dies with different convergence angles(6degrees, 10degrees, 15degrees) were prepared. Total 30 (10 for each angle) Targis/Vectris crowns were made. The restorations were evaluated for adaptation of the margin before and after cementation, then were compressively loaded to failure. Fracture surfaces of the crowns were examined using a SEM. Results. The mean marginal gap was 49micrometer for 6degrees, 55micrometer for 10degreesand 70micrometer for 15degreesand in clinically acceptable level. The mean marginal gap increased significantly after cementation. The increasing amount during cementation was the largest in the 6degrees group. The crowns on 6o convergence angle had a significantly higher fracture strength than the crowns on 15degrees angle. Mean fracture strength of total crowns regardless of convergence angle was 1390 N, which was higher than all-ceramic crowns. SEM observation showed two-mode fracture pattern. CONCLUSION: From the results of this study, all of the FRC/Ceromer crowns had clinically acceptable marginal accuracy and could withstand the bite force. Moreover, less convergent angle than all-ceramic crown might be recommended for preparation procedure.