International Journal of Periodontics & Restorative Dentistry, 02/1998

This article reports the surgical technique and outcome of simultaneous bone grafting and implant placement. A new treatment philosophy different than the principle of guided bone regeneration is presented. The technique is characterized by grafting autogenous bone into a peri-implant bone defect rather than by regenerating bone in a secluded space. Stabilization of the autogenous bone graft is achieved with a micro titanium mesh. The study sample comprised 10 implant sites in six patients. All sites were successfully treated, and postoperative healing was uneventful. The autogenous bone grafts demonstrated perfect integration upon reevaluation when the implants were recovered. The micro titanium mesh proved to be highly biocompatible, exhibited excellent mechanical properties, and avoided graft displacement and contour collapse

This study evaluates a prototype bioabsorbable physical barrier material for guided bone regeneration. Nonspacemaking dehiscence-type defects were surgically created in the right and left mandibles of six adult dogs. Each animal received six root-form threaded titanium implants. The osseous defects wre randomized to receive treatm ent by either the prototype bioabsorbable barrier composed of a copolymer of lactide and glycolide, an expanded polytetrafluoroethylene nonresorbable barrier, or no barrier (control). Clinical and histologic results after 3.5 months of wound healing indicated that exposed threads were covered when treated with the expanded polytetrafluoroethylene barrier. Minimal thread coverage was evident with the bioabsorbable barrier and the control.

Part I of the evaluation of a prototype bioabsorbable physical barrier composed of a copolymer of lactide and glycolide for treatment of bone defects in the guided bone regeneration procedure indicated that the prototype bioabsorbable physical barrier did not possess sufficient spacemaking characteristics to prevent collaspe of the barrier into the defect or against the threads of the titanium implants. The purpose of Part II was to evaluate this bioabsorbable physical barrier in combination with a supporting material to prevent barrier collaspe. Posterior mandibular teeth in three dogs were extracted and allowed to heal for 3 months. This produced localized alveolar ridge defects with a narrow buccolingual width. Six titanium threaded implants were placed in the right and left mandibles of each dog so that nonspacemaking dehiscence-type defects were produced. Two defects in each animal were randomly treated with the prototype bioabsorbable physical barrier and decalcified freeze-dried bone allograft; two defects were treated with a nonbioabsorbable expanded polytetrafluoroethylene barrier with decalcified freeze-dried bone allograft; and one defect each was treated with prototype bioabsorbable physcial barrier alone or by flap access with no barrier or bone replacement graft. The results demonstrated that both the bioabsorbable and the nonbioabsorbable barrier combined with decalcified freeze-dried bone allograft produce comparable amounts of new bone with percent bone-to-implant contact, height, width, and area. Defects treated with the prototype bioabsorbable physical barrier alone or no barrier demonstrated unfavorable results. It is suggested that a bone replacement graft is indicated when treating defects with a nonspacemaking morphology.

Spontaneous bone repair and regeneration of jawbone defects have been insufficiently studied in the dental literature. The present study analyzes a new human model designed to evaluate the basis for spontaneous bone regeneration in human jawbones. Hollow titnaium cylinders, termed bone growing chambers, were prepared with commercially pure titanium. Ten volunteers undergoing routine implant surgery were enlisted. A properly calibrated drill was used to prepare the bone-growing-chamber bed. The bone growing chamber was inserted inside the bone defect, and care was taken to submerge the cylinder at the level of the bone crest. After an adequate healing period, the bone growing chambers were retrieved with a small quantity of peripheral bo ne using a calibrated trephine bur. The retrieved specimens were processed to obtain thin undecalcified ground sections. The stable bone growing chambers showed bone tissue inside the growing space. The maturity of the regenerated bone was related to the time of removal. The bone growing chamber provides a well-defined space that is easy to preapre and to retrieve; it s dimensions are always identical and it allows quantitative measurements of bone regeneration inside the chamber space.

The term minimally invasive surgery has described the use of a surgical opening that is smaller than that routinely used to perform similar surgical procedures. A periodontal minimally invasive surgery technique for the placement of bone grafts in periodontal defects is described. The data from 10 consecutive patients on a routine supportive periodontal therapy schedule are presented. The mean healing time of the bone graft sites was 2 5.1 months, the mean probing depth reduction was 4.1 mm, and the mean attachment gain was 4.2 mm. Bone grafting using minimally invasive surgery appears to give results that are similar to results reported using other techniques. Minimally invasive surgery may have the advantage of better retention of graft material and maintenance of tissue height. Patient acceptance of surgical treatment recommendations may be higher because of the perception that minimally invasive surgery represents less surgery.

Scanning electron microscopy of root surfaces that had been ultrasonically scaled and subjected to various conditioning regimens revealed the presence of two distinct types of cracks: extensive cracks, presumed to have been caused by drying before and during sputter-coating procedures; and smaller cracks that reflected the pattern of the irregular underlying dentin. Both etching and chelating agents appear to cause demineralization of the interfacial layer between cementum and dentin, causing a peeling off of cementum and exposure o f the underlying dentin. The results suggest that burnishing the scaled root surface with either saline or any of the etching or chelating agents for at least 10 seconds, followed by soaking the cementum in 8% ethylenediaminetetraacetic acid for about 40 seconds, achieved a root surface that might be regarded as optimal for regeneration of periodontal tissues.

A new entity, the implant periapical lesion, has recently be en described. The etiology of this condition could be attirbuted to overheating of the bone, overloading of the implant, presence of a pre-existing infection or of residual root particles and foreign bodies in the bone, implant contamination during production or during insertion, or placement of the implant in an infected maxillary sinus. In this report, a titanium plasma-sprayed implant had been inserted into the mandible of a 53-year-old patient; after 5 months a fistula developed and periapical radiography showed a large radiolucent image around the apical portion of the implant. The implant was removed, and histologic examination showed necrotic bone and an inflammatory infiltrate inside the hollow portion of the implant. The etiology of the implant failure in this instance could be related to a fracture and vascular impairment of the bone inside the implant during insertion, to external contamination of the implant, or to the poor bone quality of the implant site.

Periodontal defects in adolescents or young adults are often an incidental finding within an orthodontic treatment. Most of these patients suffer from a special form of periodontal disease: juvenile periodontitis. Guided tissue regeneration offers a technique for long-term therapy in such cases. In the case presented in this report, periodontal problems were aggravated by malpositioning of the affected teeth. Orthodontic and periodontal treatment enabled the correction of malpositioning and regeneration of osseous defects.