title: Modulation of clinical expression of plaque-induced gingivitis. II. Identification of "high-responder" and "low-responder" subjects.
abstract: OBJECTIVE
  The aims of this study were to validate a randomized, split-mouth, localized experimental gingivitis model and to identify subjects with different gingivitis susceptibility.
  
  
  METHODS
  In each of 96 healthy subjects, one maxillary quadrant was randomly assigned as "test" (experimental gingivitis) and the contralateral quadrant as "control". Plaque index (PlI), gingival index (GI), gingival crevicular fluid volume (GCF), and angulated bleeding score (AngBS) were recorded in both quadrants at days 0, 7, 14, and 21. Cumulative plaque exposure (CPE), i.e. PlI over time, was calculated. Day-21 GCF was standardized according to CPE, and residuals of GCF on CPE were calculated. Two subpopulations were then defined, based on upper and lower quartiles of GCF-residual distribution and were, respectively, identified as "high-responder" (HR; n=24) and "low-responder" (LR; n=24).
  
  
  RESULTS
  At test quadrants, all parameters significantly increased throughout the trial, while in control quadrants, PlI, GI, and AngBS remained low. Significant differences were noted between test and control quadrants on days 7, 14, and 21 for all parameters. Significant increases in GI, AngBS, and GCF were observed in test quadrants over the course of the study in both HR and LR groups. Significant differences were noted between HR and LR groups for all gingivitis parameters on day 21 in test quadrants, without any significant differences in PlI or CPE between the groups.
  
  
  CONCLUSIONS
  We identified two subpopulations characterized by significant differences in clinical parameters of plaque-induced gingival inflammation, despite similar amounts of plaque deposits and plaque accumulation rates.
authors.affiliation: Research Center for the Study of Periodontal Diseases, University of Ferrara, Ferrara, Italy. l.trombelli@unife.it
authors.forename: Leonardo
authors.initials: L
authors.lastname: Trombelli
authors.forename: Dimitris N
authors.initials: DN
authors.lastname: Tatakis
authors.forename: Chiara
authors.initials: C
authors.lastname: Scapoli
authors.forename: Sabrina
authors.initials: S
authors.lastname: Bottega
authors.forename: Elisa
authors.initials: E
authors.lastname: Orlandini
authors.forename: Marina
authors.initials: M
authors.lastname: Tosi
mesh_terms: D000328:Adult; D003773:Dental Plaque / Q000150:complications*; D003774:Dental Plaque Index; D004198:Disease Susceptibility; D005260:Female; D005500:Follow-Up Studies; D005883:Gingival Crevicular Fluid / Q000737:chemistry; D005884:Gingival Hemorrhage / Q000145:classification; D005891:Gingivitis / Q000209:etiology*; D006801:Humans; D008297:Male; D015588:Observer Variation; D009910:Oral Hygiene; D010512:Periodontal Index; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric