title: Adherence of Streptococcus mutans on lithium disilicate porcelain specimens.
abstract: BACKGROUND
  Streptococcus mutans can adhere at restored tooth margins to cause recurrent caries. Limited information about surface quality and bacterial adherence is available for lithium disilicate ceramic materials.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to investigate how bacterial adherence is influenced by commercially available preparations of lithium disilicate ceramic materials.
  
  
  METHODS
  Seventeen rectangular specimens (10×10×4 mm) were fabricated for each type of lithium disilicate material: pressed (Press), milled (CAD), fluorapatite layered (ZirPress/Ceram), and glazed (Ceram Glaze). The surface roughness of each specimen was assessed before incubation with wild-type S mutans for 48 hours at 37°C with Brain Heart Infusion broth media under anaerobic conditions. Adherent bacteria were sonicated, diluted, and plated in triplicate for quantification using the plate count method to assay for colony forming units (CFUs) as an indication of bacterial viability. Statistical analysis was performed with SPSS using an analysis of variance (ANOVA) followed by the Tukey Honestly Significant Difference (HSD) test (α=.05). The Pearson r was used to evaluate the correlation between surface roughness and adherence.
  
  
  RESULTS
  The surface roughness of Ceram Glaze (1.32 ±0.19 μm) was significantly the highest, followed by ZirPress/Ceram (0.71 ±0.09 μm), which was significantly rougher than the Press (0.11 ±0.02 μm) and CAD (0.10 ±0.02 μm) groups, which were not significantly different from each other. (F=513.898, P<.001). CFUs (cells/mL) of S mutans were also significantly the highest for Ceram Glaze (61.82 ±13.76), followed by ZirPress/Ceram (28.53 ±2.40), which had significantly higher adherence than CAD (12.86 ±1.70) and Press (6.62 ±2.74), which were not significantly different from each other. (F= 201.721, P<.001). A strong positive association was found between bacterial count and surface roughness (r=.95, P<.001).
  
  
  CONCLUSIONS
  The surface roughness of differently prepared lithium disilicate ceramic restorations is closely related to the adherence of S mutans.
authors.affiliation: Resident, Department of Endodontics, Prosthodontics, and Operative Dentistry, School of Dentistry, University of Maryland, Baltimore, Md.
authors.forename: Diane T
authors.initials: DT
authors.lastname: Vo
authors.affiliation: Associate Professor, Materials Science & Engineering, College of Engineering, University of Washington, Seattle, Wash.
authors.forename: Dwayne
authors.initials: D
authors.lastname: Arola
authors.affiliation: Professor Emeritus, Department of Endodontics, Prosthodontics, and Operative Dentistry, School of Dentistry, University of Maryland, Baltimore, Md.
authors.forename: Elaine
authors.initials: E
authors.lastname: Romberg
authors.affiliation: Professor and Program Director of Residency in Prosthodontics, Department of Endodontics, Prosthodontics, and Operative Dentistry, School of Dentistry, University of Maryland, Baltimore, Md.
authors.forename: Carl F
authors.initials: CF
authors.lastname: Driscoll
authors.affiliation: Associate Professor, Department of Oncology and Diagnostic Sciences, School of Dentistry and Department of Microbiology and Immunology and Department of Pathology, School of Medicine, University of Maryland, Baltimore, Md.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Jabra-Rizk
authors.affiliation: Associate Professor, Department of Endodontics, Prosthodontics, and Operative Dentistry, School of Dentistry, University of Maryland, Baltimore, Md. Electronic address: rmasri@umaryland.edu.
authors.forename: Radi
authors.initials: R
authors.lastname: Masri
mesh_terms: D001422:Bacterial Adhesion; D015169:Colony Count, Microbial; D003764:Dental Materials; D003776:Dental Porcelain; D013295:Streptococcus mutans / Q000302:isolation & purification / Q000502:physiology*; D013499:Surface Properties; D013696:Temperature
chemical_list: D003764:Dental Materials; C493120:lithia disilicate; D003776:Dental Porcelain