Abstract:

BACKGROUND: The micro-screw anchorage is a newly used orthodontic anchorage, there are often two ways of the implant procedure: cut the gum and non-cut gum, but there is no report about the histological research of the micro-screw-bone interface in these two ways.
OBJECTIVE: To compare the osseointegration rate under two different soft tissue handling methods during implantation and to detect whether there is epithelium implantation.
METHODS: Six adult male mongrel dogs were selected, and 48 self-drilling micro-screws were prepared, one side of the upper and lower jaws of dogs was randomly selected as the experimental group, and the other side was selected as the control group; Self-drilling micro-screws were implanted without cutting the gum in the experimental group while the self-drilling micro-screws were implanted after cutting the gum in the control group, both the two groups were loaded by using NiTi-coil springs with 200 g constant force immediately. After 12 weeks, the dogs were euthanized and the bone around the micro-screws was obtained as specimen. Hematoxylin-eosin staining method was used to observe the osseointegration rate and epithelium incidences under the two different soft tissue handling methods.
RESULTS AND CONCLUSION: Both the groups obtained different levels of osseointegration. There was more fibrous connective tissue in the micro-screws-bone interface of the experimental group. The osseointegration rate in the control group was significantly higher than that in the experimental group (P < 0.01). Epithelial implantation was not found in both two groups. We conclude that micro-screws can obtain osseointegration and clinical stability with both two different soft tissue handling methods during implantation, but cutting gums implantation can acquire higher osseointegration rate than the implantation without cutting gums, the implantation with no cutting is simple in the procedure, the possibility of epithelial implantation with the two soft tissue handling methods seem to be very small.