Effects of different depths of gap on healing of surgically created coronal defects around implants in dogs: a pilot study.
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.
Yoon
Hong-Cheol
HC
Department of Prosthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
Choi
Jung-Yoo
JY
Jung
Ui-Won
UW
Bae
Eun-Kyung
EK
Choi
Seong-Ho
SH
Cho
Kyoo-Sung
KS
Lee
Ho-Yong
HY
Kim
Chong-Kwan
CK
Shim
June-Sung
JS
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*
D015921:Dental Implants