Effect of Injection molding on Flexural Properties of Denture resins

Using injection systems for processing denture resins may improve mechanical properties. Objectives: This study evaluate the effect of injection molding technique on the flexural strength (FS) and modulus (FM) of  6 denture resin 2 Type 1, Class1 (Lucitone 199, LT; Fricke HI, FH),1 Type 1, class2 (SR Ivocap, IV), 1 type 5 (Acron MC, AC) and 2 fluid resin type 2, class2  (Palapress Vario, PV;  Fricke HI Poure, FP). 

Methods: Specimens strip 64x10x3.3 were prepared from each material. Flexural properties were determined in 3-point bending after storage in water at 37°C for 50 h using testing machine at a crosshead speed of 5mm/min.

Results: Mean and standared deviation of flexural strength (MPa, n=6) and flexural modulus (Gpa, n=6) are listed.           AC                 LT                FH           IV                                       PV                    FP        

FS-CM    84.6 (5.3)      71.7 (1.5)     70.8 (3.3)      na                   FS-PO     67.5 (5.0)      58.9 (2.0)

FS-IJ       89.0 (2.8)     71.4 (3.6)     74.5 (2.5)     73.5 (2.1)        FS-IJ       73.4 (5.8)       65.0 (2.4)

FM-CM    2.10 (0.07)    1.72 (0.05)   1.70 (0.06)    na                  FM-PO    1.89 (0.10)     1.75 (0.06)

FM-IJ       2.27 (0.07)    1.78 (0.15)   1.96 (0.05)    1.80(0.06)     FM-IJ      2.04 (0.08)     1.90 (0.06)

Flexural data were analyzed by 2-way analysis of variance.Tukey-Kramer intervals at the 0.05 significance level for comparison of flexural strength and modulus among 6 resin and between 2 processing techniques were 6.1 and 2.1 MPa and 0.12 and 0.04 Gpa. Injection techniques increased FS for AC, FH, PV, and FP, and increased FM for AC, LT, FH, PV and FP. Microwave resin AC (both techniques) had the highest flexural properties of the resin tested. Conclusion: Processing of denture resins by injection molding techniques improved flexural properties.