Microvascular adaptation to transmucosal implants. A scanning electron microscopic study in the rat.

The profuse gingival microvasculature surrounding natural teeth has a unique architecture that contributes to the biologic seal and the anti-infective defense in the sulcular region. This study tested the hypothesis that this characteristic vascular arrangement is not replicated when gingival tissues adapt to a transmucosal implant. In 20 4-week-old Wistar rats, the upper first molar was extracted bilaterally and the gingiva at this site excised. Four weeks later, a 5-mm-long titanium screw was implanted at the extraction site on one side. After another 4 weeks, the rats were injected with liquid plastic resin through the carotid arteries and vascular casts prepared for scanning electron microscopy. The results showed that within 4 weeks after implant insertion, the microvasculature of the regenerated soft tissues immediately surrounding the implant had formed a characteristic arrangement that consisted of a dense subepithelial network as well as an orderly array of vertically oriented capillary loops. The density and diameter of the capillaries varied within a wide range, possibly related to the extent of healing and/or inflammatory conditions. On the contralateral, edentulous side, the capillaries formed a flattened meshwork showing a conspicuous absence of capillary loops. This study indicates that, when a transmucosal implant is inserted in an edentulous area, the mucosal microvasculature adapts and forms an arrangement very similar to that surrounding natural teeth.