Evaluation of the bond strength of different types of artificial teeth by using the surface treatment of denture bases manufactured with different methods

Muntaş, Seren. (2024). Evaluation of the Bond Strength of Different Types of Artificial Teeth by Using the Surface Treatment of Denture Bases Manufactured with Different Methods. Yeditepe University, Institute of Health Sciences, Department of Prosthetic Dentistry, Doctoral Thesis, Istanbul. The aim of this experimental study is to evaluate the effect of surface treatments and thermocycling on the bond strength of denture bases and teeth produced with Conventional, CAD/CAM, and 3D printing methods. Test samples were prepared with three different methods (heat-polymerized, CAD/CAM, 3D printing) used. Totally 192 samples were prepared from these denture bases and teeth also each method (n=64) was subdivided into four subgroups: no surface treatment (n=16), sandblasting (n=16), monomer application (n=16) and sandblasting + monomer application (n=16). Cylindrical denture base samples were designed in dimensions of 15 mm x 15 mm x 8 mm using STL data (Standard Tessellation Language) by Meshmixer software. Samples were produced from a 3D printer and CAD/CAM according to the STL data obtained by scanning the maxillary first molar tooth with the Trios 3 (3Shape Trios A/S, Copenhagen, Denmark) intraoral scanner. In sandblasting group, 250 μm Al2O3 particles were sprayed from a distance of 1 cm at 2 bar pressure for 30 seconds, followed by 5 minutes of immersion in glycerin in an ultrasonic cleaner. In the monomer group, monomer was applied with micro brushes for 60 seconds. In the sandblasting and monomer group, these two procedures were performed sequentially. Subsequently, in accordance with the guidelines provided by the manufacturer, the teeth with surface treatments applied were bonded to the samples of the denture base samples. With the samples being evenly divided into two subgroups: control and aging. Eight samples from each group were repeatedly immersed in cold water at 5°C and hot water at 55°C for 5000 cycles, with 30-second immersion period and a 10-second transfer time, recorded by the counter in the device. 5000 cycles simulate a 6-month period in the oral cavity. The specimens were subsequently submitted to a shear bond strength evaluation utilizing an Instron universal testing machine operating at a velocity of 1 mm/min. There was a statistically significant difference observed between the average shear bond strength of the No Surface Treatment, Sandblasting, Monomer and Sandblasting + Monomer groups (p=0.0001). The shear bond strength of the Sandblasting + Monomer group was statistically significantly higher than No Surface Treatment, Sandblasting and Monomer groups (p=0.0001). The shear bond strength of the Sandblasting group was statistically significantly higher than No Surface Treatment and Monomer groups (p=0.0001). There was no statistically significant difference observed between No Surface Treatment and Monomer groups (p=0.194). In Conventional method, bond strength of all surface treatment groups subjected to thermocycling was found to be significantly lower than those not subjected to thermocycling. In the CAD/CAM method, except for the Sandblasting group, the bond strength of all groups subjected to thermocycling was found to be significantly lower than those not subjected to thermocycling, while the Sandblasting group showed no statistically significant difference between thermocycled and non-thermocycled conditions (p=0.524). In the 3D Printing method, only the No Surface Treatment group's bond strength, subjected to thermocycling, was found to be significantly lower than those not subjected to thermocycling, while no significant difference was observed in other groups. There was a statistically significant difference observed among the average shear bond strength of the Conventional, CAD/CAM and 3D Print groups (p=0.0001). The bond strength of the Conventional group was statistically significantly higher than the CAD/CAM and 3D Print groups (p=0.0001) and the bond strength of the CAD/CAM group was statistically significantly higher than the 3D Print group (p=0.0001).