title: Effect of toothbrushing on shade and surface roughness of extrinsically stained pressable ceramics.
abstract: BACKGROUND
  The effect of toothbrushing on extrinsically stained pressable ceramic materials is unknown.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to investigate the effects of toothbrushing on the shade and surface roughness of extrinsically stained, pressable ceramics.
  
  
  METHODS
  Two materials, leucite-based (IPS Empress Esthetic [EE]; Ivoclar Vivadent AG) and lithium disilicate-based ceramic (IPS e.max Press [EP]; Ivoclar Vivadent AG), were studied. For each material, 24 disk-shaped specimens, 10 mm (diameter)×3 mm (height) were fabricated. Three different methods (n=8) of applying extrinsic stains were performed on each material: glazed only (G, control group); stained then glazed (SG); and stained and glazed together (T). The specimens were brushed with a multistation brushing machine under a load of 1.96 N at a rate of 90 strokes per minute with a soft and straight toothbrush (Oral-B #35) and a 1:1 toothpaste and distilled water slurry. Shade and roughness were measured at baseline and at 72, 144, 216, and 288 hours, which is equivalent to 3, 6, 9, and 12 years of simulated toothbrushing for 2 minutes twice a day. A repeated measures ANOVA with staining technique as a fixed factor was used to evaluate shade and roughness (α=.05).
  
  
  RESULTS
  For EE groups, no significant change was found after 12 years of simulated toothbrushing regarding shade and surface roughness, irrespective of staining techniques (P>.05). However, EP groups demonstrated a significant shade change and an increase in surface roughness after 12 years of simulated toothbrushing. Shade change was found to depend on the method of applying stain. For the EP-SG technique, a significant shade change was observed only at the 9- to 12-year interval (P=.047). However, the EP-T technique demonstrated a significant difference in shade between baseline and 3 years (P=.005) and in the 6- to 9-year interval (P=.005). Surface roughness was only significantly affected at baseline and 3 years for the EP-T group (P=.005).
  
  
  CONCLUSIONS
  For the shade and surface roughness of the EE groups, no statistically significant difference was found after 12 years of toothbrushing, irrespective of the staining technique. The shade and surface roughness of the EP groups were significantly statistically affected by toothbrushing time; only shade changes were found to depend on technique.
authors.affiliation: Resident, Graduate Prosthodontics, Marquette University School of Dentistry, Milwaukee, Wis.
authors.forename: Lessly A
authors.initials: LA
authors.lastname: Garza
authors.affiliation: Assistant Professor and Program Director, Postgraduate Program in Prosthodontics, Marquette University School of Dentistry, Milwaukee, Wis.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Thompson
authors.affiliation: Assistant Professor and Director, Predoctoral Prosthodontics and Biomaterials, Department of General Dental Sciences, Marquette University School of Dentistry, Milwaukee, Wis. Electronic address: seokhwan.cho@marquette.edu.
authors.forename: Seok-Hwan
authors.initials: SH
authors.lastname: Cho
authors.affiliation: Associate Professor and Director, Department of General Dental Sciences, Graduate Dental Biomaterials, Marquette University School of Dentistry, Milwaukee, Wis.
authors.forename: David W
authors.initials: DW
authors.lastname: Berzins
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D013499:Surface Properties; D014099:Toothbrushing; D014100:Toothpastes
chemical_list: D014100:Toothpastes; D003776:Dental Porcelain