Regeneration of alveolar bone and cementum following reconstructive therapy with reinforced space providing expanded polytetrafluorethylene (ePTFE) membranes was evaluated in supraalveolar mandibular premolar periodontal defects in five beagle dogs. The surgically-created defects in contralateral jaw quadrants were randomly assigned to receive the dome-shaped membrane or serve as surgical control. Flaps were positioned to completely submerge the teeth and sutured. The dogs were sacrificed 8 weeks after surgery and tissue blocks including teeth and surrounding structures processed for histology. Membrane treated defects in two animals became exposed and infected leaving intact quadrants in three dogs for histometric analysis. Parameters evaluated included defect height, height and area of regenerated alveolar bone, height of regenerated cementum, root resorption, and ankylosis. Mean defect height approximated 4.1 mm. Mean height (+/- s.d.) of regenerated alveolar bone amounted to 2.9 +/- 0.6 and 0.6 +/- 0.2 mm for membrane and control defects, respectively (P = 0.006). Corresponding values for bone area were 1.4 +/- 0.7 and 0.4 +/- 0.4 mm2 (P = 0.02). Cementum regeneration was observed in all teeth averaging (+/- s.d.) 1.6 +/- 0.3 mm for membrane treated and 0.1 +/- 0.1 mm for control defects (P = 0.01). Small amounts of root resorption were seen in all teeth with no significant difference between treatments. Ankylosis was noticed in three membrane treated and two control teeth. The present study provides a biologic rationale for space provision for enhanced bone and cementum regeneration in periodontal defects subject to reconstructive therapy.

Results of this trial demonstrate that treatment of periodontitis with subgingivally delivered doxycycline in a biodegradable polymer is equally effective as scaling and root planing and superior in effect to placebo control and oral hygiene in reducing the clinical signs of adult periodontitis over a 9-month period. This represents positive changes resulting from the use of subgingivally applied doxycycline as scaling and root planing was not limited regarding time of the procedure or use of local anesthesia.

A study was made to investigate the biological principle of new attachment of connective tissue to periodontally diseased root surfaces utilizing the previous finding that topical application of citric acid to the affected area may stimulate periodontal regeneration. Reconstructive surgery was performed on ten surfaces of nine teeth involved in advanced chronic periodontal disease. A muco‐periosteal flap was raised and the apical extent of existing subgingival calculus was demarcated by a notch made through the calculus and into the root. Following thorough instrumentation, a saturated solution of citric acid was applied to the root surface for five minutes and the flap repositioned and sutured. Four months later the teeth with attached periodontal tissues were removed and processed for histological analysis. Connective tissue regeneration characterized by deposition of new cementum, and more coronally, by tightly apposed soft connective tissue had occurred in all specimens. The junctional epithelium ended 1.2–2.6 mm coronal to the apical border of the notch in the various specimens. The results demonstrate that regeneration of periodontal tissues to a root surface that has become denuded as a result of chronic, destructive periodontal disease and that has been covered by calculus is, in fact, a biological possibility. This study does not establish whether or not acid conditioning of the root surface is a prerequisite for new attachment.

Periodontal furcation pockets were created in the mandibular premolar teeth in eight Labarador retriever dogs. Six months later, a surgical debridement procedure aimed at closing the furcation defects was carried out. On either the right or left side in each dog, a cotton pledget saturated with citric acid (pH 1) was inserted into the furcation for 3 minutes. One tooth in each animal was left untreated. Block biopsies were removed after 6 weeks and processed for histological evaluation. All of the non‐acid treated and the unoperated teeth revealed a patent, epithelialized furcation defect, whereas 21 of 23 acid‐treated furcations showed closure of the furcation in mesio‐distal sections. The instrumented root surface was covered with a thin layer of cementum to which periodontal fibers were attached. The bone level was significantly higher in the acid‐conditioning of the root surface may increase the rate of success of new‐attachment procedures and does not seem to have an adverse dffect o soft tissue healing or bone regeneration.