title: Five-year evaluation of the influence of keratinized mucosa on peri-implant soft-tissue health and stability around implants supporting full-arch mandibular fixed prostheses.
abstract: BACKGROUND
  The question of the importance of keratinized mucosa around dental implants for the prevention of peri-implant disease could not be answered in the relevant literature so far.
  
  
  OBJECTIVE
  To investigate the influence of peri-implant keratinized mucosa on long-term peri-implant soft-tissue health and stability over a period of 5 years.
  
  
  METHODS
  A total of 386 mandibular dental implants were placed in 73 completely edentulous patients, and subsequently restored with fixed full-arch prostheses. At prosthesis delivery (baseline) and after 3, 6, 12, 18, 24, 36, 48 and 60 months, modified plaque index (mPlI), modified sulcus bleeding index (mBI), distance between implant shoulder and mucosal margin (DIM) and width of peri-implant keratinized mucosa (KM) were recorded. Statistical analysis included multivariate logistic regression, multivariate ordinal logistic regression, generalized estimating equations and Bonferroni's correction.
  
  
  RESULTS
  Fifty-eight patients with 307 implants completed the 5-year study. Statistically significantly higher plaque accumulation on lingual sites (mean mPlI 0.67, SD 0.85), bleeding tendencies on lingual sites (mean mBI 0.22, SD 0.53) and larger soft-tissue recession on buccal sites (mean DIM -0.69 mm, SD 1.11 mm) were found when the width of KM was <2 mm, compared to sites with>or=2 mm of KM (mean mPlI 0.40, SD 0.68, P=0.001; mean mBI 0.13, SD 0.41, P<0.01; mean DIM -0.08 mm, SD 0.86 mm, P<0.001). The width of keratinized mucosa had no effect on bleeding tendency or plaque accumulation on buccal sites (P>0.05).
  
  
  CONCLUSIONS
  In patients exercising good oral hygiene and receiving regular implant maintenance therapy, implants with a reduced width of <2 mm of peri-implant keratinized mucosa were more prone to lingual plaque accumulation and bleeding as well as buccal soft-tissue recession over a period of 5 years.
authors.affiliation: Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA. draschrott@gmail.com
authors.forename: Alexander René
authors.initials: AR
authors.lastname: Schrott
authors.forename: Monik
authors.initials: M
authors.lastname: Jimenez
authors.forename: Jae-Woong
authors.initials: JW
authors.lastname: Hwang
authors.forename: Joseph
authors.initials: J
authors.lastname: Fiorellini
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Weber
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D003753:Dental Health Surveys; D015921:Dental Implants / Q000009:adverse effects*; D003773:Dental Plaque / Q000209:etiology / Q000517:prevention & control*; D019094:Dental Prosthesis, Implant-Supported; D003826:Denture, Complete, Lower; D005260:Female; D005889:Gingival Recession / Q000473:pathology; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation; D007633:Keratins / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology*; D009910:Oral Hygiene; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants; D007633:Keratins