Collagen deposition during wound repair in rat gingiva

The aim of this study was to examine day-by-day changes at incisional wound edge in rat molar interdental tissue with special reference to early interactions of new and pre-existing collagen fibrils. Twenty rats aged 50 days were divided into experimental groups each comprising two animals. Following incision and post-injury observation periods of 1-10 days, the rats were given an overdose of sodium pentothal and specimens prepared for light and electron microscopy. In 1-3-day post-injury specimens fibrin was replaced by inflammatory cells. Fibroblasts were found along the cut edge in 4-day post-injury specimens. Fibrillogenesis had started at 5 days post-injury. During the period of 5-10 days post-injury increasing amounts of new collagen fibrils were laid down at the wound edge. No granular material was identified at the interface of new and preexisting collagen. In standardized mesiodistal sections, bundles of newly formed fibrils regularly appeared cross-cut in relation to the tangentially cut transseptal fiber system, suggestive of a buccolingual fibril orientation at the wound edge. The ultrastructural observations indicate that during early stages of wound repair, connective tissue continuity is generally established without direct splicing of severed fibers.