Introduction

Guided tissue regeneration has become a routine treatment method in the management of bone defects resulting from periodontal diseases and deemed to be unmanageable by conservative or drug therapies.(1,2) An exhaustive literature base exists, reporting on the clinical, radiographic and histologic results of treatment of intrabony, furcation and recession type defects. A growing number of materials and techniques make this a dynamic field for both the clinician and researcher.

Among the currently available materials, the clinician has choices that range from synthetic to osseous allografts/autografts/xenografts, non-resorbable e-PTFE, and resorbable membranes of synthetic/allogenic/xenogenic origin. Emdogain, an enamel matrix protein, has also been shown to enhance new connective tissue attachment and new alveolar bone formation in animal studies.(3) There is no clear consensus on which currently available products work most predictably; evidence-based decision-making is still in its early stages. Bone allografts, which are commonly used in periodontal and implant regeneration therapy, are typically processed into granule form. Recent product development has resulted in several user-friendly materials, including bone matrices, gels and putties. Resorbable barriers are gaining increased acceptance and are considered equivalent to e-PTFE membranes to support regeneration, and have the added advantage that retrieval is unnecessary.(4) The following two case reports illustrate the results that are possible using two entirely different product combinations: the first using Dynagraft gel and Biomend collagen membrane and the second using Emdogain in combination with Dynagraft matrix.

CASE 1

This 22-year-old male presented with the chief concern of recent swelling and discomfort associated with his lateral incisor (22), ultimately resulting in the development of a buccal fistulous tract. The patient was in good health and a non-smoker. The patient was referred by his dentist to an endodontist, who found normal vitality results.

Extraction of this tooth was recommended by the endodontist. The patient was subsequently referred by his dentist for a periodontal assessment. The clinical evaluation included the following findings: normal buccal probing depths and severe bone loss on the palatal aspect of tooth 22, ranging from 9 to 14 mm, centered around a deep palatal developmental groove. Bleeding and discharge on probing were recorded. A buccal fistulous tract between teeth 21 and 22 was noted. A periapical radiograph confirmed severe bone loss with partial destruction of the buccal and lingual cortices in the mid to apical root region. Bone loss did not appear to extend around the root
apex. The clinical examination of the remainder of the dentition was non-significant.

A decision was made to pursue a guided tissue regeneration procedure. Dynagraft gel (47% demineralized bone matrix [DBM] suspended in an aqueous poloxamer) was selected as the material of choice because of the complex bone loss pattern and anticipated difficulty in material delivery. The poloxamer facilitates the action of DBM or growth factors by retention and slow release of bioactive material at the surgical site.(5) Confinement of the material using the collagen-based membrane, Biomend, was selected to eliminate the need for re-entry.

The treatment protocol involved local anesthesia with Ultracaine DS Forte (Hoechst-Roussel, Canada Inc.) infiltration. Pre-operative medications included 600 mg Ibuprofen, 500 mg Amoxicillin and pre-procedural 0.12% chlorhexidine digluconate rinse. Buccal incisions did not involve the marginal tissues as probing confirmed an intact and normal periodontium in the cervical area, with bone loss limited to the mid-root region. A trap door approach, with adequate lateral extension beyond the osseous defect margins, was used. The palatal approach consisted of an internally beveled marginal incision involving one tooth on either side of the defect, with vertical releasing incisions mesial and distal to the defect for access reasons.

Following full thickness flap elevation, complete degranulation of the defect was achieved using hand and ultrasonic instrumentation. A deep palatal groove was readily apparent upon debridement. Its obliteration through odontoplasty was deemed impossible without risk of developing secondary endodontic complications. Root preparation was completed and the root surface was treated with tetracycline paste for three minutes.

Limited recontouring using finishing burs (Midwest FF9903) was carried out. Dynagraft gel was syringed into the defect from both the buccal and palatal aspects and compacted with bone pluggers. Two layers of appropriately shaped Biomend membrane were applied to both buccal and palatal aspects of the defect. An additional layer may delay membrane resorption, which typically takes six to eight weeks. The flaps were sutured with 5-0 gut sutures (Hu-Friedy) achieving primary closure over the membranes. No protective periodontal packing was used in this case.

Post-operative instructions were provided, requesting limited masticatory function in this area and no oral hygiene procedures performed until otherwise instructed. Post-operative medications included 400 mg Ibuprofen Q6H PRN, Amoxicillin 500 mg q8h x 7 days, and a 0.12% chlorhexidine digluconate rinse q12h x 7 days. The healing period was uneventful. Follow-ups were scheduled after one, three, six, and 12 weeks of healing. Minor tissue swelling was initially noted on both the buccal and palatal aspects. Normal oral hygiene procedures were gradually reintroduced over the six weeks following surgery. The site was clinically reassessed at 12 and 24 months post-surgery. Radiographs were obtained at 12 and 24 months. The 12 month clinical radiographic reassessment confirmed resolution of the buccal fistula and significant, but incomplete pocket depth reduction on the palatal side (5mm residual probing depths over the palatal developmental groove area). The site was free of inflammation and did not bleed or suppurate on probing. The site was asymptomatic with no clinical changes noted after a two-year follow-up period. 

CASE 2

This 46-year-old male patient was referred for periodontal evaluation of an isolated periodontal defect causing gingival swelling over tooth 21. The patient did not report any pain, but noted increasing tooth mobility over several months preceding the evaluation, as well as a bad breath problem. The patient was in good health and a non-smoker. Clinical inspection of the site revealed a broad osseous defect on the buccal aspect of tooth 21, extending to the mesial and distal line angles. Bleeding on probing and suppuration were recorded. Significant subgingival roughness was noted. The tooth mobility was recorded as 2. No other significant periodontal findings were noted. The radiograph revealed bone loss extending to the apical root region. Endodontic treatment was completed approximately 10 years ago.

A decision was made to attempt a GTR procedure, coupled with apical surgery and retro fill. The products in this case included Emdogain, coupled with Dynagraft matrix (60% DBM/40% glycoprotein matrix) saturated in Emdogain, as the defect morphology was not inherently space-making. DBM mixed with type 1 atelopeptide collagen forms a matrix or sponge, and has been shown to be osteoinductive in clinical use.(6) The surgical protocol involved local anesthetic administration with Ultracaine DS Forte. Pre-operative medications included a preprocedural 0.12% chlorhexidine digluconate rinse, 600 mg Ibuprofen and 500 mg Amoxicillin. Tooth 21 was temporarily splinted to the adjacent 11 and 22 with a flowable composite material. Using a dog model, Wikesjo UME and Nilveus R have shown that wound stability is critical for GTR success.(7) Marginal incisions were limited to the buccal of the area 11 to 22, with releasing incisions to allow adequate access for apical surgery.

After full thickness flap elevation, the site was degranulated. Root preparation was completed using hand and ultrasonic instrumentation. As the defect involved the root apex, an apicoectomy and amalgam retro fill was completed. The root surface was chemically modified using 37% phosphoric acid as recommended by the manufacturer of Emdogain at the time. This has since been modified to 24% ethylenediaminetetraacetic acid (EDTA) gel (Prefgel), which is more tissue compatible. Reconstituted Emdogain was applied to the prepared and dried root surface. Dynagraft matrix (1 x 1 x 0.5 mm) was saturated with the remaining Emdogain and adapted over the root surface. Primary tissue closure using 5-0 gut sutures was accomplished following a periosteal release at the base of the releasing incisions. A periodontal dressing (Coepak) was applied and maintained for one week.

Post-operative medications included Ibuprofen 400 mg Q6H PRN, Amoxicillin 500 mg q8h x 7 days, 0.12% chlorhexidine digluconate rinse q12h x 7 days. Follow-ups were scheduled after 1, 3, 6, and 12 weeks with long-term follow-ups at one and two years. The post-operative period was free of complications; post-surgical pain was brief and mild. The splinting was maintained for three months at which time it debonded, as reinforcement was not used.

The one-year post-operative follow-up findings were the following: no symptoms or compromised function as described by the patient. The clinical evaluation revealed minimal buccal probing depths (< 3 mm), no bleeding on probing, no discharge, and no visual signs of inflammation. The darkened gingival appearance noted post-surgically can be attributed to the discoloured root surface. The radiographic evaluation at one year suggested that there was improved bone density and resolution of the widened periodontal ligament space. A two-year follow-up revealed similar findings. As endodontic re-treatment was considered pre-operatively, it is essential to radiographically monitor the site, as the possible role of contaminated lateral canals has not been ruled out. 

Discussion

The illustrated and contrasting cases underscore the fact that guided tissue regeneration is a predictable treatment modality, regardless of material selection. The results clinically and radiographically demonstrate that differing materials and their combinations promote healing over previously diseased root surfaces. The first case illustrates a complex defect, with a through and through defect in the mid root segment and deep broad crater on the palatal aspect. The second case demonstrates a buccal dehiscence defect associated with an endo-perio lesion.

Several studies have previously shown that these are challenging defects to regenerate and less successfully treated in contrast to 3-walled defects.(8) The study of Gestrelius et al., has shown that Emdogain is no longer detectable on a root surface two weeks following its application, thus it may be inadequate to predictably result in regeneration in unfavourable defect morphologies.(9)

It is our opinion that Emdogain alone would act as an adequate scaffold supporting periodontal regeneration in a non-space-making defect; hence the decision to use a human allograft matrix to support the overlying soft tissue. Histologic evaluation would be necessary to clearly define whether a true and functional periodontal apparatus has been regenerated. Although GTR procedures do not have 110% success rates, their predictability is high and their use is warranted in the management of bone loss. Certainly, it is critical to point out that defect morphology is a key issue in predicting treatment success and long-term prognosis. Other elements that have a major role in treatment success include tooth stability, adequacy of the root preparation, soft tissue management/closure, as well as patient hygiene, bacterial microflora, and smoking status. Material selection and combinations may be important issues, although not supported by the results achieved by the contrasting methodologies used in the case reports in this article.

References

1.  Palcanis K. Surgical pocket therapy: Ann Periodontol 1996; 1:589-629.

2.  Laurell L, Gotlow J, Zybutx M, Persson R. Treatment of intrabony defects by different surgical procedures. A literature review. J. Periodontol 1998; 69: 303-313.

3.  Sculean A, Chiantella GC, Windisch P, Dons N. Clinical and histologic evaluation of human intrabony defects treated with an enamel matrix protein derivative (Emdogain). Int J Periodontics Restorative Dent 2000; 20: 375-381.

4.  Dos Ajos B, Novaes AB, Meffert R, Porto Barboza E. Clinical comparison of cellulose and expanded poly tetra fluoroethylene membranes in the treatment of class II furcations in mandibular molars with 6-month re-entry. J. Periodontol 1998; 69: 454-459

5.  Coulson R, Clokie C, Peel S. Collagen and a thermally reversible poloxamer deliver demineralized bone matrix (DBM) and biologically active proteins to sites of bone regeneration. Proceedings from Portland Bone Symposium 1999; 619-637.

6.  Babbush CA. The use of a new allograft material for osseous reconstruction associated with dental implants. Implant Dent 1998; 7; 205-212.

7.  Wikesjo UME, Nilveus R. Periodontal repair in dogs: Effect of wound stabilization on healing. J. Periodontol 1990; 61: 719-724.

8.  Tonetti MS, Pini Prato G, Cortellini P. Factors affecting the healing response of intrabony defects following guided tissue regeneration and access flap surgery. J. Clin Periodontol 1997; 23: 548-556.

9.  Gestrelius S, Andersson C, Johavsson AC, Persson E, Brodin E, Brodin AM et al. Formulation of enamel matrix derivative for surface coating. Kinetics and cell colonization. J. Clin Periodontol 1997; 678-684.