Treatment of Furcation Defects
The term furcation involvement refers to the invasion of the bifurcation and trifurcation of multirooted teeth by periodontal disease. According to Larato, whose study of the incidence of the furcation defects reported that the mandibular first molar is the most common site, the maxillary premolars are the least common; and the number of furcation involvements increase with age. In his paper discussing the anatomical factors related to furcation involvements, Larato found that of 188 furcation involvement, 75% occured on the root surface closer to the CEJ than on the noninvolved root surface (65% on the maxilla and 85% on the mandible). 13% of the furcation involvement exhibited cervical enamel projections. Furcation involvements complicated the treatment methodology due to its bacterial retentive nature and anatomical factors which prevents visualization and access for treatment. According to Caranza and Newman, furcation involvement microscopically is simply a phase in the rootward extension of the periodontal pocket. In its early stages, there is a widening of the periodontal space, with cellular and fluid inflammatory exudation, followed by epithelial proliferation into the furcation area from the adjoining periodontal pocket. Extension of the inflammation into bones leads to resorption and reduction in bone height. The bone destructive pattern may produce horizontal loss, or there may be angular osseous defects associated with infrabony pockets. Plaque, calculus, and bacterial debris occupy the denuded furcation space. These debris and the difficulty of controlling plaque in the furcation area is responsible for the presence of the extensive lesions in this area and the persistence of the lesion or disease progression.
Glickman in 1953 introduced the classification of the furcation defects, allows a better understaning of patient prognosis and therapy for furcation involvement. Furcations has been classified as grade I, II, III, and IV according to the amount of tissue destruction. Grade I is the incipient or early lesion. The pocket is suprabony, involving soft tissue. There is slightly bone loss in the furcation area. The examiner probe usually penetrated less than one millimeter from the entrance of furcation. Grade II is the partial bone loss (cul de sac), or when the examining probe penetrate more than one millimeter from the entrance of the furcation. Bone is destroyed on one or more aspect of the furcation, but the portion of the alveolar bone and periodontal ligament remains intact, permitting only partial penetration of the probe into the furcation. Grade II involvement diagnosis is complicated by the fact that the x-ray images are usually demonstrated superimposition of the root, the lose proximity of the roots, thick bone remaining between the root, or the angulation of x-ray can conceal the furcation. Grade III is the total bone loss with through and through opening of the furcation. In this type of furcation, interradicular bone is completely absent, but the entrance of furcation is occluded by the soft tissue. These lesion will appear on the proper angled radiograph as a radiolucent area between the roots. Grade IV is similar to grade III, only with the gingival recession exposing the furcation to view. The radiographic picture of grade IV is similar to that of grade III. Examination of the furcation is facillitated with the use of Nabers probe. Tarnow and Fletcher later on further described the furcation defect with the vertical component classification. Each grade of furcation is further subdivide into three subgroup, depending on the distance from the bottom of the defect to the roof of the furcation; subgroup A, 0-3mm; subgroup B, 4-7mm; and subgroup C, 7mm or more. According to the classification of intrabony pocket of Goldman and Cohen in 1958, the furcation defect is truely a no wall defect, of which the prognosis is poor due to lack of osteogenic cell proliferation into the area or more precisely, lacked of bone wall providing the cells of periodontal ligament which contributes most importantly to the regenerative process.
In treating the furcation defect, the etiology of the periodontal lesion must be understood. According to Waerhaug, trauma from occlusion, especially when occured concurrently with the presence of local factors such as plaque and calculus, can assumed the secondary role. Plaque and calculus causes the area to be inflammed, edema occurs, as the result tooth is extruded and therefore become traumatized and sensitive. Caranza noted that trauma from occlusion is particularly should be suspected when the furcation involvement demonstrated crater like or angular deformities in the bone and especially when the bone destruction is localized to one of the roots. Other factors may play the role such as the enamel projection into the furcations, which occurs about 13% of multirooted teeth, or the proximity of the furcation of the cemento-enamel junction, which occured in about 75% of cases of the furcation involvement. Finally, furcation involvement may be the direct result of the endodontic problem from the lateral or accessory pulpal canal in the furcation defect and thus extending the pulpal infection into the area. If detected early, endodontic therapy can be carried out and no periodontal therapy needed to be instituted.
Problems in the treatment of furcations are outlined by Newman and Caranza as the tooth anatomical factor, the bone morphology and architecture, and the quality and morphology of the gingiva concerning the width of attached keratinized gingiva and the vestibular depth. As described partially above, the tooth anatomical factors included the root trunk length, the concavity of the inner surface of exposed roots, the degree of separation of the roots, and the presence of enamel projection. The root trunk length is the distance from the CEJ to the entrance of furcation. If it is short, the furcation will be involved early. If it is long, the furcation will be hard to be instrumented in the therapy. The thick buccal or lingual bony ledge may favor the formationof trough like vertical lesion in the furcation area. A thin radicular bone will result in the complete loss of the bone, and no vertical lesion will form. Robert Bower studied the furcation morphology in relation to periodontal treatment and found that the furcation entrance diameter of the 114 maxillary and 103 mandibular first permanent molar teeth, are smaller than the blade face width of commonly used periodontal curettes in 58% of the furcation examined. Because of this size disparity, curettes when used alone may not be suitable for root preparation in this area as part of periodontal therapy.
Frank G. Evertett, Ellis Jump, Thomas Holder, and George Williams conducted a study of the bifurcation of 328 extracted molars, and found that in a majority of specimens was the presence of a distinct ridge (73%), running across the bifurcation in a mesiodistal direction. This ridge was referred to as the intermediate bifurcational ridge. It originates about 2mm from the height of the furcation, run across the furcation, and ends high up on the mesial root, there blending into the concavity characteristic for the distal surface of the mesial root of this tooth. The buccal bifurcational ridge was found more acute than the lingual one in about 40 per cent of the teeth. Histologic findings showed that the intermediate ridge has the basis in dentin on which the extensive cementum deposition occurs. The buccal and lingual ridges, on the other hand, are esssentially dentin formations covered with only a small amount of cementum.
Treatment of furcation involvement depnes largely on the extent of lesion, as classified by Glickman, ranging from debridement to regenerative procedures to extraction. Treatment of grade I involvement usually involved scaling and curettage or by gingivectomy. The resolution of inflammation and repair of the periodontal ligament and adjacent bone margin occurs as the result of pocket elimination therapy. The furcation does not need to be enterred and debride since the bone destruction is minimal. As one might expect from the healing response of the scaling and curettage or by gingivectomy, the healing results in the establishment of long junctional epithelium. Goldman outlined the therapy of the incipient bifurcation involvement which involved determined the topography of the lesion, removing tooth substance and soft tissue to obliterate the bifurcation involvement. In this way, the diseased gingival attachment (pocket formation) and topography are treated to obtain a healthy attachment after healing; the area is then accessible and cleansed. Today, with the advancement of guided tissue regenerative therapy, placement of barrier membrane in repair of furcation defects had been carried out successfully in both animal studies and human clinical applications (Caffesse et. al.). This regenerative procedure results in regeneration response, with the establishment of new periodontal apparatus (new bone, cementum, and cells of periodontal ligament).
Treatment of grade II involvement included scaling and root planing as the minimal, placement of bone graft, or application of biodegradable barrier. Osseous grafting in the past has been used with osseous coagulum, autogenous intraoral bone, iliac crest bone, freeze dried bone with autologous bone, and hydroxyappatite. The results with bone grafting procedures are not predictable since epithelium downgrowth is not retarded. Regeneration via placement of barrier membrane shows promising result, as reported by Becker and Becker, and Pontoriero, Lindhe, and Nyman in their clinical study. Alan Polson, G. Lee Southard, Richard L Dunn, Anne P Polson, J. Billen, and Larry Laster used the polylactic acid biodegradable barrier in nine patient with mandibular molar class II defect and reported horizontal gain of 3.0 mm and vertical gain of 3.3 mm in attachment level. They characterized of three type of response that were associated with barrier membrane. The first type of tissue response was characterized by no or minimal inflammation associated with the site throughout the observation period. The second type of response involved greater magnitude of inflammation present at one month and subsided few weeks later. The third type of response was characterized by initial mild inflammation at one week, followed by granulation type of tissue response between the barrier region and the root surface at approximately one month. This granulation tissue mature over 2 to 4 month period. This kind of response occurs when there is less adaptation of membrane. One important concepts to be noted is that the goal of regenerative furcation therapy is to reduce the furcation defect to a size that is maintainable by routine hygiene methods and mechanical instrumentation. This concepts is emphasized by Hamp, Nyman, and Lindhe in their observation of five years followed up studied on periodontal treatment of multirooted teeth using GTR. The successful treatment of the multirooted teeth was probably the consequence of the quasi total elimination of plaque retention areas from the bi/trifurcation area and the meticulous oral hygiene by the patients. In this respect, the goal is to convert the class II furcation into class I furcation. The success rate with this occurence is of 56%. The results of this multicenter study is consistent with previous studies which indicated that clinical periodontal regeneration can occur after using the technique directed toward preferential cell repopulation of the root surface area by cells originating from the periodontium. Histological study in monkey using bioresorbable material by Gotlow, Lars Laurell, Sture Nyman, Mathsen, Rylander, and Bogentoft reported of new supporting bone after six weeks of healing. The material is completely resorbed at six to twelve months. In the final stages of resorption, macrophage and multinuclear cells were present within the tissue that replace the material. In summary, utilization of resorbable and nonresorbable membranes to exclude the epithelial and connective tissue cells is a recognizable procedure. Clot formation and stabilization, space provision, neovascularization, epithelial cell exclusion, and complete gingival coverage are necessary in any GTR procedure to ensure regenerative success.
Finally, treatment of class III and IV involvement are carried out with very limited success. Pontoriero, Lindhe, and Nyman reported excellent result in the control study of incipient grade III furcation involvements in mandibular molars treated according to the principle of GTR. In this study, the defect is very small, the grade III was not identified until after surgical exposure. Treatment of class III and IV often involved the removal or resection of the root. This method is utilized when there is advanced bone loss around one root with an acceptable level of bone around the remaining root and there is no angular positioning of the root. The divergence of the roots is desirable, thus long straight diverged root are preferrable over curve or converge conical roots. Endodontics are to be carried out prior to resective therapy. Root resection or root amputation referred to the procedure which involved the removal of a root without the removal of any portion of the crown. When root and its corresponding crown portion are cut and removed, the procedure is called a hemisection. Bisection or bicuspidization referred to the procedure of which a molar is simply cut into two separate mesial and distal portions, with removal of any part of the root or crown. The two portions of the teeth will require crowns and thus mimicking two premolars.
Morton Amsterdam in 1947 and Samuel Rossman in 1954 described the technique of hemisectionof multirooted teeth. According to them, the indications included a deep one or two wall intrabony pocket involving one root, with the supporting bone around the other root relatively normal; or a three wall infrabony pocket that does not respond to routine form of therapy for attaining a new attachment; a periodontal involvement of a multirooted tooth in either the bifurcation or trifurcation area that is not accessible for self maintenance and which results in frequent periodontal break down; a deep carious lesion extending into the root or bifurcation or trifurcation area of the multirooted tooth. Morton Amsterdam described hemisection as a “combined surgical and therapeutic procedure performed on multirooted teeth whereby an untreatable root (or roots) is surgically removed and potentially well functioning segment is endodontically treated and restored, preferrably by fixed prosthesis.” Originally, the technique of vital root resection required all jperiodontal surgery to be completed with normal healing prior to resection. However, E.W. Haskell, Harold Stanley, and Steve Goldman investigates the technique of which the vital root resection at the same time as periodontal surgery with follow up over 1 to 3 year and found that the result compares favorably to that of the original technique.
Long term study was done to evaluate long term results of treating furcation defects using different modality of therapy. Results from Ira Franklin Ross and Robert Thompson study showed favorable long term functional survival rate of 341 teeth (88%) 5 to 24 years after treatment, despite the fact that many teeth had at least one root with 50% or less of bone support before treatment. Radiograph of 292 teeth (75%) showed no significant change in bone support 5 to 24 years after treatment, while those of 8 teeth (2%) suggested improvement. Moreover, 94% of the teeth did not have endodontic before, during, or after the study. Endodontic therapy was not significant factor in retention of the 341 teeth. The treatment modality involved a combination of scaling, curettage, occlusal correction by coronal reshaping, periodontal surgery of soft tissue, and oral hygiene instruction. There is no osseous surgery, root amputation, hemisection, or reshaping the cervical area of the tooth. In their followed up study, they found that furcation involvement of the maxillary molars are more frequently detected by radiographic examination than clinical examination. On the other hand, furcation involvement was detected more frequently in mandibular molars by clinical examination than by radiographic examination. Burton Langer, Stephen D. Stein, and Barry Wagenberg evaluated root resection with a ten year study and published the result in 1981. They showed that with root resection, although the intermediate postoperative results are gratifying, they are not always lasting, even when surgery is properly performed. Most breakdown did not become evident until 5 to 10 years had elapsed. Nevertheless, most failures resulted from endodontic or restorative problems and not periodontal disease. The most common cause of tooth failure in this study was root fracture of the mandibular molars. They suggested that the parafunctional occlusal habits along with the small size of these roots made these teeth susceptible to fracture. Finally, they concluded that only teeth with large roots and large clinical crowns should be utilized; isolated mandibular teeth should not be used for terminal abutments of fixed bridges, nor should the tipped teeth. Periodontally, teeth with significant vertical bone loss within the furcation should not be treated with this technique because pocket elimination procedures usually compromise the support of these teeth to the point that they offer little support to the splint and are very difficult to maintain. Kenneth Kalkwarf, Wayne B. Kaldahl, and Kashinath D. Patil compared of 558 molars which were treated with one of four types periodontal therapy: coronal scaling, root planing, modified widman surgery, flap with osseous resectional surgery. All types of therapy produced reduction in probing depth, with flap combined with osseous resetional surgery was the most effective, followed by modified widman flap, root planing, and coronal scaling. A mean net loss of horizontal probing attachment was present after two years of maintenance care, regardless of the treatment modality employed. The study showed that progression of periodontitis is different than that found on other tooth surface. Breakdown continue years after followed up and lead to tooth extraction.
Bernard Gantes, Michael Martin, Steve Garrett, and Jan Egelberg performed study on treatment of periodontal furcation class II defect using the freeze dried, decalcified allogenic bone graft along with citric acid root conditioning and coronally positioned flaps secured by crown attached suture. On the average, 67% of the defect volume became filled with bone, 43% of treated defects were completely closed by bone filled. No difference was observed between defects treated with and without bone grafts.
In summary, furcation defect has been a challenge concerning choosing an appropriate modality of treatment. A clinician needs to have a firm grasp of the topography of the defect prior to decide on the periodontal procedures. Regenerative procedures with membrane can help to reduce the defect to the environment that can be maintained by patient-doctor oral hygiene effort. Plaque control and elimination of local factors must be carried out in order to achieve a stable result over a long period of time. For class I and II furcation defect, regenerative therapy can be carried out. For class III and IV, root resection or amputation or bicuspidization seemed to be an appropriate choice. Finally, tunnelization or flap surgery combined with osseous surgery can provide the patient a maintainable result with access to the defect for his or her oral hygiene effort.

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References

1. Larato, DC. Furcation involvements: Incidence of distribution, Journal of Periodontology 41: 499, 1970.

2. Larato, DC. Some anatomical fators related to furcation involvements, Journal of Periodontology, 46: 608, 1975.

3. Waerhaug, J. The furcation problem, etiology, pathogenesis, diagnosis, therapy, and prognosis. Journal of Clinical Periodontology, 7: 73, 1980.

4. Waerhaug, J. The infrabony pocket and its relationship to trauma from occlusion and subgingival plaque. Journal of Periodontology, 50: 355, 1979.

5. Newman, Caranza. Text book of Clinical Periodontology, eight edition. W.B. Saunders Company, 1996.

6. Goldman, HM. Therapy of the incipient bifurcation involvement. Journal of Periodontology, 29: 112, 1958.

7. Hamp, SE., Nyman, S., Lindhe,J. Periodontal treatment of multirooted teeth. Results after five years. Journal of Clinical Periodontology,2: 126, 1975.

8. Becker W., Becker B.E., Berg L. , et al. New attachment after treatment with root isolation procedures; report for treated class II and class II furcations and vertical osseous defects. Int Journal of Periodontal Restorative Dentistry, 8(3):9, 1988.

9. Pontoriero R., Lindhe J., Nyman S., et al. Guided tissue regeneration in degree II furcation-involved mandibular molars. A clinical study. Journal of Clinical Periodontology, 15: 247, 1988.

10. Everett, FG, Jump,E. Holder, T., Williams, G.C. The intermediate bifurcational ridge: a study of the morphology of the bifurcation of the lower first molar. Journal of Dental Research, 37: 162, 1958.

11. Amsterdam, M., Samuel R. Technique of Hemisection of Multirooted teeth. The alpha Omega, 4: 1960.

12. Bower, R.C. Furcation Morphology Relative to Periodontal Treatment. Furcation entrance architecture. Journal of Periodontology, 50:23, 1979.

13. Ross, F., Thompson, R.H. A long term study of root retention in the treatment of maxillary molars with furcation involvement. Journal of Periodontology, 49: 238, 1978.

14. Ross, F., Thompson, R.H. Furcation involvement in Maxillary and mandibular molars. Journal of Periodontology, 51: 450, 1980.

15. Langer, B. Stein, S.D., Wagenberg, B. An evaluation of root resections. A ten year study. Journal of Periodontology, 52: 719, 1981.

16. Haskell, E.W., Stanley, H., Goldman, S. A new approach to vital root resection. Journal of Periodontology 51: 217, 1980.

17. Kalwarf, K., Kaldahl, W., Patil, K. Evaluation of furcation response to periodontal therapy. Journal of Periodontology, 59: 794, 1988.

18. Gantes, B., Martin, G.B., Garett, M., Egelberg, J. Treatment of periodontal furcation defects. II) Bone regeneration in mandibular class II defects. Journal of Clinical Periodontology, 15: 232, 1988.