Guided tissue regeneration (GTR), a regenerative surgical technique, has been evaluated in several controlled clinical trials. Favorable clinical results have been reported for treatment of Class II furcation defects in mandibular molars. Cury and colleagues1 and Lekovic and colleagues2 reported significant probing depth reductions, gains in horizontal and vertical clinical attachment levels and bone height gain, as well as the possibility of complete closure of some Class II furcation defects after GTR.
This case report and other studies suggest a high risk of root resorption and ankylosis after guided tissue regeneration.
GTR involves placement of a membrane between the root surface and the mucoperiosteal flap. This may prevent the epithelium and the gingival connective tissue of the flap from contacting the root surface, allowing the periodontal ligament cells to repopulate this surface and regenerate cementum, periodontal ligament and alveolar bone.3 However, preventing apical migration of the epithelium poses a risk of producing root resorption, which means that cells from bone and gingival connective tissue (which are able to induce root resorption and ankylosis) may repopulate the root surface before periodontal ligament cells do so.4–6 Several authors have reported that root surface resorption and ankylosis were sequelae to periodontal healing after GTR therapy.7–12
GTR has resulted in the development of several types of membranes. After publication of the initial case report involving the use of a millipore filter,13 nonresorbable membranes were used, which must be removed in a second surgical procedure. This shortcoming was resolved by using bioabsorbable barriers. Most bioabsorbable membranes are based on collagen, polylactic acid, polyglycolic acid or copolymers of polylactide-glycolide acid.14
Several authors reported positive results in animals and humans after use of a bioabsorbable polylactic acid membrane (Guidor matrix barrier, Guidor AB, Huddinge, Sweden).1,8,15–18 This product (which is no longer manufactured) was made of amorphous polylactic acid softened with a citric acid ester for malleability, which facilitated clinical handling. Gottlow and colleagues7 and Gottlow16 reported that the matrix barrier maintained its functional stability for a minimum of six weeks, after which the membrane was resorbed slowly by hydrolysis, without interfering with the regenerative healing process. Bioresorption of this material was completed within 12 months.7,16
Biomodification of the root surfaces using tetracycline promotes connective tissue attachment in vitro.19 Tetracycline has been used in root coverage procedures,20 flap surgery21 and bone grafting.22 Wikesjö and colleages23 reported the development of root resorption after tetracycline root conditioning in animals, and Ben-Yehouda24 reported it in a patient.
We describe a case of root resorption and ankylosis in a tooth that underwent GTR therapy with a bioabsorbable membrane. In addition, a 10 percent tetracycline solution had been applied to the root surface.
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CASE REPORT
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Clinical and radiographic data.
In March 1997, a general dentist referred a 40-year-old woman to the Graduate Clinic of the School of Dentistry of Piracicaba, University of Campinas, Brazil, for periodontal treatment. Two of us (P.C., E.S.) diagnosed the patient as having generalized advanced chronic periodontitis, with a Class II furcation defect on the buccal aspect of tooth no. 32. The tooth was vital and had 2 millimeters of keratinized mucosa and 4.4 mm of probing depth.
One of us (P.C.) performed the clinical measurements using a University of North Carolina periodontal probe and verified them with a caliper.1 The plaque and gingival index values were 0 (plaque absent) and 2 (bleeding on periodontal probing), respectively.25,26 The patient was a nonsmoker, free of systemic disease and not taking any medications.
The clinician performed full-mouth scaling and root planing, removed plaque-retentive factors (such as restorative overhangs) and gave detailed oral hygiene instructions to the patient. She then decided to use GTR to treat the Class II furcation defect.
The clinician obtained vertical bitewing radiographs and made probing depth measurements before surgery and at six, 12 and 18 months after surgery.
The surgery consisted of making an intrasulcular incision and a mucoperiosteal flap and removing granulation tissue. The clinician carefully removed the epithelium from the inner surface of the flap. Using manual and rotary instruments, she thoroughly scaled and planed the root surface. She rinsed the area with sterile saline and applied a 10 percent tetracycline solution to the root surface for three minutes.
The membrane (Guidor matrix barrier) was fitted to cover the furcation and 3 to 4 mm of alveolar bone beyond the defect. Using the preplaced resorbable ligature, the clinician tightly fit the coronal portion of the membrane to the tooth. She positioned the mucoperiosteal flap coronally and secured it with interdental expanded polytetra-fluoroethylene sutures to ensure coverage of the membrane.
After surgery, the patient received 100 milligrams of doxycycline per day for two weeks and 0.12 percent chlorhexidine mouthwash twice a day for eight weeks. The dentist removed the flap sutures after 14 days. She saw the patient every two weeks for six months for professional prophylaxis and to reinforce oral hygiene procedures. Thereafter, the dentist saw the patient every three months for 18 months for maintenance therapy.
Healing was uneventful in the site, and the membrane did not become exposed.
At the one-year follow-up examination, the patient experienced a gain in vertical (2.9 mm) and horizontal (0.3 mm) clinical attachment levels. She also experienced an increase in the gingival recession level (0.8 mm) and a reduction in probing depth (from 4.4 mm to 2.3 mm). Nevertheless, the furcation defect remained classified as a Class II furcation defect. The final plaque and gingival index values were 0 and 1, respectively. No clinical or radiographic complications were present during the first 21 months of follow-up. Two years after surgery, the patient complained of pain in the tooth.
The clinical examination revealed root resorption through the pulpal floor of tooth no. 32. The resorption cavity reached the pulpal chamber. Because the resorption cavity was small, radiographic examination did not reveal the resorption. After surgical inspection, the clinician extracted the tooth.
Histologic findings.
After extracting the tooth, the clinician immersed it immediately in 10 percent buffered formalin along with the soft tissue filling the furcation defect. After 48 hours, the tooth was decalcified in a solution of 50 percent formic acid and 20 percent sodium citrate at room temperature.
After three months, the tooth and soft tissue were washed in running water, dehydrated and embedded in paraffin. The clinician cut serial sections (5 micrometers thick) and stained them with hematoxylin-eosin. We then used light microscopy to examine the sections.
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RESULTS
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The soft tissue that filled the furcation defect was composed of sulcular epithelium overlaying connective tissue that contained inflammatory infiltrate. The inflammatory infiltrate consisted of mononuclear cells and the remainder of the membrane (Figure 1
).
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ABSTRACT
CASE REPORT
