International Journal of Periodontics & Restorative Dentistry, 04/1993

A classification scheme that systematizes the wide range of regenerative potential of common extraction site topographies is presented. Within this system, the parameters for immediate implant placement and preliminary ridge augmentation are discussed. In addition, a new adjunctive role for orthodontic extrusion is introduced. This approach is intended to manipulate hopeless teeth to modify their local defect environments, thereby enhancing the predictability of subsequent implant placement at those sites.

To elicit information about the phenomenon of intrusion of natural tooth abutments in implant-connected prostheses, a survey was distributed to clinicians with varied experience. Although practitioners with more experience in fabricating implant-supported dentures connected to natural teeth reported fewer instances of intrusion, it cannot be concluded that this observation is significant. The cause of intrusion is probably multifactorial, and respondents suggested several possible causative factors: disuse atrophy, debris impaction, impaired rebound memory, and mechanical binding. Because apical migration of abutment teeth affects occlusion and oral hygiene, the authors make several recommendations for treatment planning for patients who have natural dentition adjacent to proposed implant sites.

This paper reviews types of preparation margins and the placement of the restoration's margins in relation to the gingival margin in prosthetic reconstruction of periodontally involved teeth. The emergence margin, a new type of preparation margin, is presented through three case reports. The requirements for successful use of the emergence margin are discussed.

The periodontal fenestration model was used in four young mongrel dogs to evaluate the ability of vertical root surface grooving to enhance and direct cell outgrowth and subsequent formation of new attachment at 2- and 6-week healing intervals. In each dog, three fenestration wounds were made on each side of the mandible. On the control side, the roots were planed to dentin, a barrier membrane was sutured over the wound, and the flaps were replaced over the membrane. The experimental side received three vertical grooves followed by membrane placement and flap replacement. Histologic and histometric analyses were performed to determine the amount of new bone, cementum, and ankylosis and maturation of wound healing. Grooved wounds demonstrated greater cementum and bone formation, primarily in the early wounds, in addition to a more mature attachment at 6 weeks. Grooving the root surface may enhance initial cell adhesion and proliferation, thereby accelerating new attachment formation.

Two cases are presented to illustrate a technique for the use of the principles of guided tissue regeneration for root coverage and gingival augmentation in humans. The paper discusses the advantages of GTR over a variety of conventional root coverage techniques.

This study compared the caries inhibition and microleakage of two liners under amalgam restorations. Thirty-two molars received mesio-occlusal and disto-occlusal Class II cavity preparations. Calcium hydroxide was randomly placed as a liner in one preparation of each tooth and glass-ionomer cement liner was placed in the other. Amalgam restorations were placed. Teeth were axially loaded and an acid-protective varnish was placed. Teeth were placed into artificial saliva for 3 months, thermocycled, and cycled through a caries challenge. Sections were obtained from 20 teeth and photographed under polarized light. The remaining teeth were placed in 2% basic fuchsin and sectioned. A t-test indicated that restorations with glass-ionomer cement liners exhibited significantly less demineralization and microleakage than did restorations with calcium hydroxide liners.