Topical application of citric acid to a root surface which has been scaled and root planed results in exposure of collagen fibrils of the dentin matrix. The purpose of this study was to examine the healing of gingival connective tissue adjacent to a root planed and subsequently acid conditioned root surface and to determine whether the exposure of dentin or cementum matrix collagen would facilitate the reestablishment of an attachment between the healing connective tissue and the root surface. Full thickness flaps were raised and labial alveolar bone removed over maxillary incisor roots of seven Labrador retrievers. The exposed root surface was planed before etching with citric acid (pH 1) for 3 min. The flap was then repositioned at its original level. Block sections were obtained after 7, 14, 21 and 42 days and the interface between the root surface and the healing wound tissue studied by light and electron microscopy. Compared to conventional flap surgery in the same animals, application of citric acid to the instrumented root surface resulted in an improved rate of connective tissue healing as well as a rapid and consistent reestablishment of connective tissue attachment through extensive interdigitation of new and old collagen fibrils at the tooth‐gingiva interface. Subsequent reinforcement of the established connective tissue attachment included recalcification of the acid‐affected dentin and deposition of new cementum.

Periodontal furcation pockets were created in mandibular premolar teeth of three beagles and subsequently treated by reconstructive procedures including flap surgery, root planing and application of citric acid. Block biopsies removed after 1, 2, 3 and 6 weeks showed new attachment of connective tissue to the periodontally involved root surface. This was established by progressive interdigitation of new collagen fibrils and the acid‐exposed fibrils of the dentin matrix along the root planed surface as well as within the orifice of dentinal tubules. The results supplement those of a previous study (Ririe, Crigger & Selvig 1980) and show that attachment of soft connective tissue to a root planed and acid‐conditioned dentin surface can be achieved by the same mechanism irrespective of whether the root surface has been surgically denuded or has been exposed to the environment of an experimental periodontal pocket.

Oral actinomycosis is not a common disease, but it can cause massive destruction. This article reports a case of implant failure associated with actinomycosis. A 55-year-old Caucasian male patient had tooth #20 extracted years ago and an implant placed 3 years ago. The #20 implant area developed an abscess about 1½ years after implant placement. Radiographic findings revealed a large radiolucency on the mesial aspect of the #20 implant. The implant was surgically removed and the lesion thoroughly debrided. The patient experienced severe pain when the apical soft tissue was curreted following implant removal. A periapical radiograph revealed that the lesion approached the mental foramen. A short course of antibiotics was prescribed. Histological observation found sulfur granules, which were found to be actinomycotic colonies. Peri-implant actinomycosis was diagnosed. No recurrence had occurred at the 1-year follow-up.