title: Effects of different depths of gap on healing of surgically created coronal defects around implants in dogs: a pilot study.
abstract: BACKGROUND
  This study investigated the bone growth pattern in surgically created coronal defects with various depths around implants in dogs.
  
  
  METHODS
  Four mongrel dogs were used. All mandibular premolars were extracted under general anesthesia and left to heal for 2 months. After ostectomy, bony defects were prepared in test sites, using a stepped drill with a diameter of 6.3 mm and two depths: 2.5 mm (test sites 1 [T1]) and 5.0 mm (test sites 2 [T2]). In the control sites, the implants were placed after ostectomy without any coronal defects. T1, T2, and control sites were prepared in the right and left sides of the mandible. Six implants, 3.3 mm in diameter and 10 mm in length, were placed in each dog; the implants were submerged completely. Two dogs were sacrificed 8 weeks after surgery, and the other two dogs were sacrificed 12 weeks after surgery. The stability of all implants was measured with a resonance frequency analyzer after placement and after sacrifice. All sites were block-dissected for ground sectioning and histologic examination.
  
  
  RESULTS
  After 12 weeks of healing, only T2 were not filled fully with bone. At week 8, the mean bone-to-implant contact (BIC) was 47.7% for control, 43.6% for T1, and 22.2% for T2. At week 12, the control BIC was 56.7% and the 2.5-mm defect had a greater BIC (58.8%). However, in the 5-mm defect, the BIC was 35.1%. At insertion, stability was reduced at sites with a greater defect depth. Similar stability was noted in all specimens after 8 and 12 weeks of healing.
  
  
  CONCLUSIONS
  Bone healing between an implant and marginal bone was compromised at sites with a deeper defect when the width of the bone defect was 1.5 mm.
authors.affiliation: Department of Prosthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Hong-Cheol
authors.initials: HC
authors.lastname: Yoon
authors.forename: Jung-Yoo
authors.initials: JY
authors.lastname: Choi
authors.forename: Ui-Won
authors.initials: UW
authors.lastname: Jung
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Bae
authors.forename: Seong-Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Kyoo-Sung
authors.initials: KS
authors.lastname: Cho
authors.forename: Ho-Yong
authors.initials: HY
authors.lastname: Lee
authors.forename: Chong-Kwan
authors.initials: CK
authors.lastname: Kim
authors.forename: June-Sung
authors.initials: JS
authors.lastname: Shim
mesh_terms: D000818:Animals; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D004285:Dogs; D020007:Implants, Experimental; D008297:Male; D008334:Mandible / Q000601:surgery*; D016348:Osseointegration / Q000502:physiology*; D010027:Osteotomy; D010865:Pilot Projects; D014732:Vibration; D014945:Wound Healing / Q000502:physiology*
chemical_list: D015921:Dental Implants