In the following case report, we describe the placement of such an implant and the histologic follow-up of the implant and surrounding tissues after the patient’s death 28 years later. What the patient experienced clinically, and what was revealed histologically after her death led us to consider the nature and timing of osseointegration; the definitions of, and factors contributing to, implant success and failure; and the nature of periodontal tissue compared with peri-implant tissue.

	CASE REPORT

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The patient was a 57-year-old woman. In 1971, one of us (S.P.) placed an implant and subsequent restoration in her maxilla. The implant functioned until the patient’s death at age 85 years, 28 years later. Her medical history was unremarkable at the time of implant placement.

For more than 20 years before receiving the implant, the patient had worn a retainer—a single-tooth cast partial denture with anterior and posterior clasps and no cross-arch stabilization—in the maxillary right first and second premolar area. She was unhappy with the clasping on tooth no. 6. In addition, tooth no. 3 was inclined mesially (Figure 1).

View larger version (120K): [in this window] [in a new window]   Figure 1. Note the severe mesial drift of the maxillary right first molar.

Procedure. The following materials and methods were typical of those used at the time. The patient received penicillin VK 24 hours before surgery. She was anesthetized with lidocaine/1:50,000 epinephrine. The clinician made a crestal incision using a high-speed air-powered handpiece. In this preautoclave era, the clinician sterilized the area using alcohol wipes. Irrigation was performed through the handpiece (using the city water supply). Biofilms and contaminated dental unit waterlines were not an issue at the time.

The dentist used materials and methods that were typical of those used at the time.

To prevent possible air emboli, the clinician turned off the chip blower (located below the handpiece turbine). The dentist made the initial incision in bone using a no. 700 carbide bur, which produced a cut approximately 6 millimeters deep. He repositioned the bur so that only half of the shank was fastened in the chuck, which extended the cut to approximately 8 mm. After this initial cut, the dentist continued the procedure using a no. 700 XXL bur in the hand-piece. Again, he slipped it partially out of the chuck to give it more length.

Titanium blade implant. The dentist sterilized a no. 105 titanium blade implant (Park Dental Research, New York City) (Figure 2) in an endodontic bead sterilizer. Table salt was used in the sterilizer because clinicians believed that if glass beads got into the surgical site, it might be impossible to retrieve these foreign bodies. Typically, however, patients had no adverse reactions to the sterile glass beads in the surgical site.

View larger version (120K): [in this window] [in a new window]   Figure 2. On the left, a no. 105 titanium blade implant (Park Dental Research, New York City). On the right, a posterior blade implant commonly referred to as a "chicken blade." This shallow blade was used commonly in the posterior mandible to avoid involvement with the inferior alveolar nerve.

The clinician snipped off the distal section with laboratory wire-cutting pliers, polished the edges with an abrasive wheel and finished polishing with a rubber-finishing wheel. The implant then was washed with liquid soap and tap water to remove any cutting and polishing particles. The dentist then resterilized the modified implant in the salt sterilizer and placed it in the prepared surgical bone trough. Using a titanium implant placement tool and mallet, he seated the underside of the head to the crest of the ridge. The wound was closed with 3/0 silk sutures (Figure 3).

View larger version (126K): [in this window] [in a new window]   Figure 3. Radiograph of the implant after healing.

The dentist removed the sutures one week later and recemented the temporary crown. Three weeks after surgery, the patient’s healing was within normal limits. The dentist removed the temporary crown and made a final impression using a no. XX copper band and compound. Bite registration and counter models were made, the temporary crown was recemented and the patient was discharged.

Placement of gold crown. The laboratory constructed a full-cast gold crown with acrylic facing, and incorporated cingulum rests into the crown to fit into rest preparations originally made on teeth nos. 3 and 6 for the partial denture. The dentist cemented the crown with zinc phosphate cement (Figures 4 and 5, page 327). We should point out that although the rests were placed to fill in space on teeth nos. 3 and 6, they might have been instrumental in achieving the restoration’s stability and longevity.

View larger version (91K): [in this window] [in a new window]   Figure 4. Final restoration with a gold crown with mesial and distal wings.

View larger version (144K): [in this window] [in a new window]   Figure 5. Radiograph of implant with its final restoration.

	HISTOLOGIC REPORT

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On the patient’s death, the endosteal blade dental implant, adjacent teeth and surrounding hard and soft tissues were retrieved for histologic sectioning. A portion of the maxilla containing the implant (completely encased by the retrieved maxillary tissue), along with intact gingival tissues, was sent to the Medical College of Georgia–American Academy of Implant Dentistry Retrieval Foundation–Retrieval Service and Registry Center in Augusta in August 2000. The sample was placed in a vial containing 10 percent formalin, with the gold crown still affixed to the implant.

The sample was dehydrated in ethanol and acetone, then infiltrated in methyl methacrylate monomer and polymethyl methacrylate, or PMMA. The sample was embedded in PMMA for sectioning after bench curing and heating in a vacuum oven. An oral pathologist obtained five serial sections after cutting the material with a diamond wafering blade affixed to a slow-speed saw. The sections were ground and stained with a toluidine blue/basic fuchsin mixture. The oral pathologist then examined them with a photomicroscope (Zeiss Axiophot, Carl Zeiss, Thornwood, N.Y.) using normal transmitted light as well as polarizing light microscopy and Nomarski differential interference contrast imaging.

The sample showed an intact area of maxilla containing a metallic blade implant with no visibly apparent coating. Only one small region of the implant surface was apposed by trabecular bone. The bulk of the implant surface was apposed by oriented bands of fibrous connective tissue. This connective tissue adhering to the apical aspects of the implant appeared healthy, with minimal evidence of any inflammatory cells.

An overview of the implant surface disclosed the fibrous connective-tissue support for the blade implant. The cervical area of the implant revealed severe crestal resorption. An intact internal basal lamina separated the crevicular epithelium from the interstitial tissues, which contained a severe chronic and acute inflammatory cell infiltrate. Inflammatory cells included polymorphonuclear leukocytes, lymphocytes and mast cells. However, the oral pathologist observed an intact junctional epithelium. Even though the tissue and cells appeared slightly necrotic (owing to the postmortem period), the oral pathologist observed osteocytes within the bone that supported the implant. He noted that the bone did not directly appose the implant, "but it was close enough to provide implant stability, with probably some minor mobility" (Medical College of Georgia, Augusta, unpublished histology report, 2000).

	DISCUSSION

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We should note that the retrieved implant was well-supported by fibrous connective tissue with associated bone support. The bone was not positioned directly at the implant surface, but was separated by areas of fibrous connective tissue. The connective tissue was more random and less organized than would be an arrangement of alveolar crest fibers and horizontal, oblique and apical fibers of an alveolar dental ligament (Figure 6). The supporting tissues were primarily healthy in appearance, with no extreme inflammatory cell infiltrate in the apical aspects of the interface between the tissue and the implant. The chronic and acute inflammatory cell infiltrate that was disclosed in the cervical area of the implant could have been due to a lack of adequate oral hygiene later in life. The intact epithelial basal lamina suggests that the inflammatory process was not extremely lengthy.

View larger version (85K): [in this window] [in a new window]   Figure 6. Histologic slide of the implant enveloped by pink bands of connective tissue (hematoxylin-eosin stain, x 4 magnification).

In the mid-1980s, Brånemark (as quoted by Sykaras and colleagues⁵) defined osseointegration on the light microscopic level as "a direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant." A few years later, a more clinical definition was given as a process in which clinically asymptomatic rigid fixation of alloplastic materials is achieved and maintained in bone during functional loading.⁶ "Clinical osseointegration ... implies histologic osseointegration, i.e. contiguous contacts of alveolar bone with the implant surface."⁷

The term ‘osseointegration’ did not exist when the implant in this patient was placed.

In our patient, histologic osseointegration certainly was not achieved, as no direct connection between living bone and the implant was demonstrated. In addition, it is unlikely that the implant would have passed the more clinical definition of the term. Because no standardized tests for rigidity were performed on the implant immediately before the patient’s death, we do not know for certain whether this implant would have been considered rigid by today’s standards. However, given the nature of its fixation, it is highly unlikely it would have passed the clinical test.

Practically, a more apt definition of the relationship between the implant and the maxilla would be one of biotolerance. "Biotolerance" implies that the implant was not rejected when implanted into living tissue but, rather, was surrounded by a fibrous layer in the form of a capsule.⁸ The implant also was biocompatible in that it resulted in a predictable host response in its specific application (that is, its use as support for the crown). This biocompatibility was enhanced by the titanium metal. Titanium interacts with biological fluids through its stable oxide layer, which forms the basis for its exceptional biocompatibility. Titanium is the material of choice for intraosseous applications, as it was 30 years ago.⁹ The stoichiometric composition of commercially pure titanium allows its classification into four grades that vary primarily in regard to oxygen content. We do not know the oxygen content of the titanium that made up the implant in this patient.

Definitions of success, today and yesterday. By today’s standards, clinicians would consider an implant without osseointegration to be unsuccessful and would recommend that it be removed. However, in retrospect, we can question the success of this implant in a different way: "Did this implant serve the patient for a significant number of years (in this case, for the rest of her life)?" Based on several factors, among them the health of her peri-implant tissue, her lack of symptoms and the adequate clinical functioning of the implant and the restoration, the answer to this question is an unqualified "yes."

The crown continued to function in this patient until she died. This longevity may be attributable, in part, to the crown design, which incorporated mesial and distal wings that fit into rest seats on adjacent teeth. Although it is possible that osseointegration did occur in the 28-year span to a greater degree than was seen after the patient’s death, we must conclude, based on the evidence, that significant osseointegration did not occur. If it did, then it had reversed to a significant degree by the time the sample was taken.

There might not even have been a high degree of complexity of the fibrous tissue capsule that was considered a standard of success 28 years ago. However, success occurred according to a standard by which we can judge this case, and by which we judge much of what we do in dentistry: the implant functioned successfully for this patient and fulfilled her expectations, as well as those of her dentist.

	CONCLUSION

TOP ABSTRACT CASE REPORT HISTOLOGIC REPORT DISCUSSION CONCLUSION REFERENCES

 
In this case report, we described the placement, clinical history and postmortem histologic evaluation of a blade vent implant placed in the maxilla of a 57-year-old patient in 1971. Case selection, method of implant placement, and restoration and implant maintenance were appropriate at the time. With advancements in the field of implantology during the past 30 years, standards of success are significantly different from what they were in the early 1970s. However, our review of this case reveals that the implant and restoration functioned well for the patient for the rest of her life, and the dentist served her well by offering her this relatively new dental treatment.