title: Increased crown-to-implant ratio may not be a risk factor for dental implant failure under appropriate plaque control.
abstract: OBJECTIVE
  The aim of this study was to evaluate whether increased crown-to-implant (C/I) ratio influences implant stability or not under proper healthy control of peri-implant mucosa. The hypothesis of this study is that implant stability can be maintained despite High C/I, under appropriate plaque control.
  
  
  METHODS
  Five male Beagle-Labrador hybrid dogs (2 years old) were used. Their bilateral mandibular premolar extraction was performed. After allowing 12 weeks for bone healing, 3 types of vertical marginal bone loss were simultaneously prepared randomly. Then, 30 titanium implants were placed in the edentulous areas and defined as High C/I, Mid C/I and Low C/I groups. This time point was designated as the baseline (0 Week). Twelve weeks after implant placement, metal superstructures were cemented to the implants and an occlusal plate was set at the opposite side. At the same time, Calcein green was injected for remodeling evaluation. Implants were loaded by feeding the dogs a hard pellet diet. Tooth brushing was performed 5 days per week during the study to maintain healthy peri-implant mucosa. Twenty-four weeks following implant placement, the interface structure was evaluated clinically, radiologically, and histologically.
  
  
  RESULTS
  Implant stability quotient (ISQ) increased with time in all 3 groups, without any significant correlation with the C/I value (p >0.05). Moreover, mean marginal bone loss adjacent around implants in all 3 groups ranged between 0.11 and 0.19 mm, with no significant difference (p >0.05). Many fluorescence-labeled bones are shown in the High C/I group. It is considered that high remodeling activity prevent marginal bone loss in the High C/I group and this may provide favorable implant stability under proper plaque control.
  
  
  CONCLUSIONS
  These findings suggest that increased C/I may not be a risk factor for implant failure if the peri-implant mucosa is kept healthy, as was the case in this animal model.
authors.affiliation: Department of Advanced Prosthodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan. shinsuke0517@hiroshima-u.ac.jp
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Okada
authors.forename: Katsunori
authors.initials: K
authors.lastname: Koretake
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oue
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Akagawa
mesh_terms: D000818:Animals; D003442:Crowns; D015921:Dental Implants; D003773:Dental Plaque / Q000000981:diagnostic imaging / Q000517:prevention & control*; D004285:Dogs; D008297:Male; D011475:Prosthesis Failure; D011859:Radiography; D012307:Risk Factors
chemical_list: D015921:Dental Implants