Abstract
The influence of the dental plaque accumulation on the tissues around implants in animals has been confirmed in recent experimental studies. However, various results were reported in these studies. Therefore, this study was carried out to compare the effects of long-standing plaque accumulation with or without the placement of ligatures in the peri-implant tissues. Three beagle dogs were used in this study. The mandibular right and left 3 rd and 4 th premolars were extracted to establish recipient sites for implants. After 3 months of healing, 10 titanium fixtures were implanted and straight post connections were carried out in the 2nd stage procedure after 3 months. After 1 month of healing, biodegradable surgical sutures were placed in a submarginal position around the neck of fixture abutments. New ligatures were made in addition every month. The remaining implants were not ligated. Radiographic and chinical examination comprising Plaque Index (PlI), Gingival Index(GI), loss of attachment, gingival recession and mobility were evaluated at ligated implants and non-ligated implants 1～8 months after the implantation of the straight post. Microorganisms around implants were checked at 3 and 7 months. All dogs were sacrificed at the end of the experiment. The animals were perfused with a fixative, and block biopsies were obtained from the implant sites. The biopsies were prepared for histometric analyses. The results from the clinical and histological examinations revealed that (1) the loss of attachment around ligated implants increased more than non-ligated implants, (2)histometric signs of tissue destruction were more pronounced at the ligated implants than non-ligated implants. In the ligated sites, the mean bone loss was 2.7±0.8 mm, non-ligated site 1.3±0.5 mm.
