Date of Award
Spring 2015
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Thompson, Geoffrey
Second Advisor
Cho, Seok-Hwan
Third Advisor
Berzins, David
Abstract
The purpose of this study was to investigate the effects of toothbrushing on surface roughness and shade change of extrinsically stained pressable ceramic restorations. Materials and Methods: Two materials, IPS Empress Esthetic and IPS e.max Press, were studied. For each material, 24 disc-shaped specimens, 10mm (diameter) x 3mm (height) were fabricated. Three different methods (n=8) of applying extrinsic stain was performed on each material: Glazed (G): glazed only (control); Stain then Glaze (SG): stained and fired, then glazed and fired. Stained and Glazed (T): glazed and stained together. Samples where brushed using a multi-station brushing machine. Each specimen was brushed for 72, 144, 216 and 288 h (equivalent to 3, 6, 9 and 12 years of simulated toothbrushing twice a day for 2 min) with a force of 200 g at a rate of 90 strokes/min using a soft, straight Oral-B #35 toothbrush and a 1:1 toothpaste and distilled water slurry. Roughness and color were evaluated at baseline and every 3 year equivalent up to 12 years of simulated toothbrushing. Results: No significant difference was found for surface roughness or shade change over time irrespective of technique for the IPS Empress Esthetic (EE) groups. IPS e.max Press (EP) demonstrated an increase roughness over time (P<.01) irrespective of technique (P=.709). Shade change over time depended on the technique (P=.005). The stain then glaze (EP-SG) behaved better over time (P=.039). Conclusions: Within the limitations of this study it can be concluded that no clinically significant shade change for both IPS Empress Esthetic and IPS e.max Press should be expected after 12 years of toothbrushing. IPS Empress Esthetic stains and glaze were more resistant to toothbrush abrasion.