title: Evaluations of epithelial sealing and peri-implant epithelial down-growth around "step-type" implants.
abstract: OBJECTIVE
  Implant designs that can stimulate and integrate with an epithelial wound-healing process may significantly enhance the efficacy of dental implants. Here, we evaluated the potential of "step-type" implant systems to improve the sealing between the peri-implant epithelium (PIE) and the implant surface, and investigated the effect of implant structure on PIE down-growth.
  
  
  METHODS
  Right maxillary first molars were extirpated from rats and implanted with either a straight-type or a step-type implant varying in step height and/or width (N(s): 0.8 mm height, 0.1 mm width; W(s): 0.8 mm height, 0.2 mm width; H(s): 0.4 mm height, 0.1 mm width). Maxillae were harvested at various time points over 16 weeks to evaluate laminin-5 distribution as an indicator of wound healing and PIE formation, horse-radish peroxidase (HRP) penetration as a measurement of epithelial sealing, and PIE down-growth formation.
  
  
  RESULTS
  In all implant models, the PIE formed from the oral sulcular epithelium and spread apically along the implant surface. In the W(s) group, HRP penetration was detected only in the coronal region of the PIE at 4 weeks, whereas in the straight-type, it was observed in the apical region and the connective tissue. At 16 weeks, the W(s) implants exhibited markedly less PIE down-growth than the Con, N(s) or H(s) implants, and were equivalent to that observed in natural teeth.
  
  
  CONCLUSIONS
  The step-type implant system may have the potential for improving epithelial sealing at the tissue-implant interface, as well as reducing apical PIE down-growth, thus enhancing dental implant efficacy.
authors: Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Higashi-ku, Fukuoka, Japan. atyuta@dent.kyushu-u.ac.jp
authors: Ikiru
authors: I
authors: Atsuta
authors: Yasunori
authors: Y
authors: Ayukawa
authors: Yoichiro
authors: Y
authors: Ogino
authors: Yasuko
authors: Y
authors: Moriyama
authors: Yohei
authors: Y
authors: Jinno
authors: Kiyoshi
authors: K
authors: Koyano
mesh_terms: D000497:Alloys; D000818:Animals; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D004846:Epithelial Attachment; D007124:Immunoenzyme Techniques; D020007:Implants, Experimental; D008297:Male; D008437:Maxilla; D008963:Molar; D016348:Osseointegration; D057873:Peri-Implantitis / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D013499:Surface Properties; D014025:Titanium; D014945:Wound Healing
chemical_list: D000497:Alloys; D015921:Dental Implants; C031462:titanium alloy (TiAl6V4); D014025:Titanium