A Review of Osseous Resective Surgery

The treatment of periodontal diseases associated with attachment loss has involved a variety of approaches. While the goal of periodontal surgical treatments is to access the root surfaces for proper debridement, the decision to remove or reshape the supporting bone has been controversial. This paper will address the controversy as well as discuss surgical pocket therapy directed toward pocket reduction through recontouring the underlying bone.

Over the years, the treatment of periodontal diseases associated with attachment loss has involved numerous surgical and nonsurgical approaches. Although the concept of pocket reduction is a fundamental objective of periodontal therapy, discussion and controversy have been associated with the different treatment methods used. Several surgical treatment modalities have been proposed to treat the soft tissue lesions associated with periodontitis as well as to gain access to the root and supporting bone. These include the apically positioned flap with and without osseous resection, modified Widman flap surgery, open flap curettage, and several other repositioned-flap procedures. While most of these periodontal surgical treatments have as their main goal to access the root surfaces for proper debridement, it is the decision to remove or reshape the supporting bone that has produced the most controversy. This paper will address this controversy, as well as discuss surgical pocket therapy directed toward pocket reduction through recontouring the underlying bone.

Schluger is often credited with first describing osseous resective therapy. In 1949,¹ he attempted to describe and identify the rationale for and technique of osseous resective surgery for pocket elimination. He stated that total pocket elimination could be maintained only with the removal of the bony component of the pocket. He further advocated the need to reshape the bone to a physiologic form resembling the pattern of horizontal atrophy. Otherwise, the gingiva would not adapt adequately; and pockets, especially interproximally, would re-establish. In 1935, Carranza² advocated a mucoperiosteal flap approach and listed specific indications where bone should be surgically remodeled to stimulate the rebuilding of healthy support around the teeth. Since then, several people have talked about and defined osseous resective therapy. The World Workshop in Periodontics defines osseous surgery as "that aspect of periodontal surgery which deals with the modification of the bony support of the teeth."³ Sims and Carranza define osseous surgery as the procedure by which changes in the alveolar bone can be accomplished to rid it of deformities induced by the periodontal disease process or other related factors, such as exostosis and tooth supraeruption.⁴ Friedman described osseous surgery as surgical removal of the gingiva and reshaping of the bone to eliminate the pocket and correct unphysiologic architecture.⁵ What all these definitions have in common is that the goal of osseous surgery is to produce osseous contours that are consistent with the shape and form of the healthy gingival tissues. By creating a bony architecture that mimics the final shape of the gingiva, it is thought that pocket reduction cannot only be obtained, but also maintained.

Gingival tissue is elastic, that is, it tends to return to its original architectural contours. Even when deep pockets exist, the gingiva will retain a scalloped form that follows the shape of the cementoenamel junction. This form is independent of the underlying contours of the osseous crest. When the gingiva has its normal architecture and the underlying bone has a similar architecture, there is a shallow probing depth. When there is a discrepancy between the gingival tissue and the underlying bone, the difference is expressed in pocket depth. If the gingival tissues are contoured to the form of the diseased osseous crest, the irregularities created in the gingiva would not be maintained. In time, the soft tissue will round out and revert to its original scalloped pattern.

This soft tissue proliferation results in pocket depth. Residual increased pocket depths are more likely to break down, need constant and meticulous treatment in the office and at home, and present a potential nidus for reinfection. To be truly successful in reducing pocket depths, the reshaping of bone must be done with curves and slopes that mimic the contours of the healthy gingiva. The tendency of gingiva to assume a pre-existing form dictates the architecture of the bone that must be created to achieve a stable result. Therefore, the eradication of the periodontal pocket is dependent upon the correction of the underlying bony deformity. Surgical elimination of the pocket with resultant minimal probing depths allows the patient access for proper plaque control and facilitates maintenance by the therapist. This is the basis of osseous resective surgery.

Procedures used to correct osseous defects have been classified into two groups. In 1955, Friedman defined these two procedures as osteoplasty and osteoectomy.⁵ Friedman defined osteoplasty as a plastic procedure in which the periodontal pocket is eliminated and the bone reshaped to achieve physiologic contour of the bone and the gingiva overlying it. In this operation, the bone that is reshaped is not part of the attachment apparatus, thus no bony support of the tooth or teeth is lost. Friedman defines osteoectomy (also referred to as ostectomy), as an operative procedure in which bone that is part of the attachment apparatus, is removed to eliminate a periodontal pocket and establish gingival contours that will be maintained. Ostectomy requires the loss of some bony support of the tooth or teeth, and the amount involved will be an important criterion for its use.

The terms positive architecture and negative architecture are also widely used when discussing osseous surgery. These terms describe the position of the interdental bone in relation to the radicular bone. Positive architecture refers to a situation in which the osseous crest follows the shape of the cementoenamel junctions, that is, the interdental bone is more coronal than the radicular bone. Negative architecture is used to describe a situation in which the osseous crest does not follow the shape of the cementoenamel junctions, that is, the interdental bone is more apical than the radicular bone. The discrepancies between the shape and position of the osseous crest and the gingival margin result in pocket depths.

Indications for osseous surgery as described by Carranza and Carranza Jr.⁶ are to recontour bone that forms part of the outer wall of the pocket, to prevent recurrence of the pocket, and to reshape the alveolar crest, establishing a normal fiber arrangement. Indications for osteoplasty according to the World Workshop in Periodontics³ are buccal or lingual bony ledges, tori, etc.; intrabony defects associated with tilted molars; shallow buccal or lingual intrabony defects; flat interproximal areas; the elimination of deep interproximal defects to achieve physiological contour; incipient furcation involvements; and for improvement of alveolar contours for flap adaptation. Ostectomy has been indicated for the elimination of interdental craters, intrabony pockets not amenable to reattachment procedures, horizontal alveolar bone loss with irregular marginal bone height, and moderate and advanced furcation involvement.³

The most common indication for osseous resective surgery is to treat the shallow two-wall osseous crater. Osseous craters are concavities in the crest of the interdental bone that are confined within the facial and lingual walls of the alveolus. Practically all craters have a slope from buccal and lingual walls to the base. These slopes represent more than two-thirds of the crater.

The site of the initial periodontal lesion is usually the interproximal area, with the two-wall osseous crater as the most common type of osseous defect. The osseous crater has been found to make up about one-third of all defects and about two-thirds of all mandibular osseous defects.^7,8 They are twice as common in posterior segments as in anterior.^7,8 The greater frequency in the posterior areas is probably due to the thickened alveolar housing in the posterior, as well as the wider interproximal contact area between adjacent teeth. In the anterior region, the slender cone of the interproximal bone is gradually blunted by progressive bone resorption. Crater formation in the anterior occurs only after extensive bone loss. The bone between the posterior teeth presents a flat occlusal surface in health. Bone destruction rapidly creates an intrabony crater. To a great extent, the thickness of bone and the pattern of inflammation determine the pattern of bone loss on the lateral and medial surfaces of the teeth. Thin plates of bone resorb in an apical direction without crater formation. Thicker ledges of bone undergo incomplete resorption, resulting in the formation of a crater or well adjacent to the tooth.^7-9 Reasons for the high frequency of interdental craters overall include the facts that the interdental areas are more difficult to clean, and only a small percentage of people floss regularly. Other possible explanations include the lack of keratinization of the gingival col area and vascular patterns from the gingiva to the center of the crest that may provide a pathway for inflammation.^7-9

Contraindications for osseous resective surgery include deep osseous craters, three-wall osseous defects, moderate to deep circumferential defects, and bony defects situated on the buccal aspect of terminal mandibular molars associated with the external oblique ridge. It is important to remember that osseous surgery is best-suited to treating early and moderate periodontal defects. Advanced periodontal lesions or isolated deep craters may require some bone contouring, but not for the express purpose of eliminating the defect. Selective extraction, grafting procedures, and/or root amputations are often necessary to manage such areas. Three-wall bony defects should be managed by regenerative techniques since removal of supporting bone would often jeopardize the future of the affected tooth, as well as the adjacent teeth. Other precautions must also be taken into consideration before one decides to use osseous surgery. If too much supporting bone must be sacrificed on sound teeth to retain a neighboring affected tooth, it may be better to sacrifice the involved tooth or leave a residual bony defect. If a furcation will be exposed because of an extensive sacrifice of bone, it may be better to accept a deep gingival crevice. It should also be noted that osseous surgery should not be done in areas that have pocket depths of less than 5 mm. Shallow pockets treated with osseous surgery result in a net loss of attachment.^10-14 Other contraindications for surgery are inadequate plaque control by the patient, noncompliance with supportive periodontal therapy, and certain medical and anatomic conditions.

Although the concept of osseous surgery was introduced into the United States in the late 1940s, a critical description of surgical guidelines, tenets, and limitations was essentially unavailable for decades. The lack of standardized guidelines and the variability in surgical technique among clinicians made it difficult to scientifically compare the effectiveness of the surgical treatment modalities. Clinicians differed in opinion concerning the initial incisions, amount and location of bone removal, degree of flap elevation, and methods of suturing. The variability in postoperative maintenance regimes further complicated the transition of these procedures from research to clinical practice. This disparity fueled a healthy exchange of ideas that has improved the modern design of clinical research and helped define the periodontal surgical procedures now provided for patients on a daily basis. However, this disparity also made for great difficulty in scientifically determining the superiority of one procedure over another. Thus was born the controversy that is still debated.

Part of the controversy surrounding osseous surgery has involved the extent of bone removal necessary for the creation of a positive osseous architecture. Ochsenbein said, "The primary objective of osseous surgery is to remove the minimal amount of bone that will meet the needs of an adequate architectural form."¹⁵ A study by Selipsky16 found that during osseous surgery, the average height of supporting bone removed per tooth was only 0.6 mm. Loss of interproximal bone support was negligible, except where severe angular defects were present. He also found that the majority of ostectomy performed was midbuccal, midlingual, or palatal adjacent to interproximal defects. Even on these surfaces, only about 1 mm of supporting bone was removed. Selipsky also noted that removal of buccal or lingual bone seems to be less important in terms of tooth support than the removal of interproximal bone. This is because roots are generally irregular in shape, and the buccal or lingual surfaces have a smaller surface area than the flattened root form extending buccolingually. The result is that interproximal bone gives more support in terms of surface area than does buccal or lingual bone, especially in the posterior.¹⁶

It was also once believed that removal of supporting bone might increase tooth mobility. However there is no scientific evidence to support this claim. Selipsky found that teeth initially loosened postsurgically, but returned to pre-operative mobility levels within one year. This response occurred without any form of splinting. Only time and a healthy environment were needed to obtain the reduction in mobility to presurgical levels.¹⁶ Smith and colleagues, in a study comparing osseous resection with flap curettage, also confirmed these results. They found no net change in tooth mobility at six months postsurgery.¹⁴

The most complete treatise on osseous surgery to date is Ochsenbein's "Primer for Osseous Surgery."¹⁷ In this work, he describes in great detail the classification of molar osseous craters and the variations of molar root morphology that affect surgical decision-making. These relationships are critical to understanding the disease process, and they aid in proper surgical management of the posterior regions. The dimensions of the osseous crater and the size of the molar root trunk give an indication as to how much bone is present coronal to the level of the furcation. This information dictates the limits of osteoplasty and ostectomy performed in every periodontal osseous surgery. A maxillary first molar with a short root trunk, for example, may have only 1 mm of radicular bone coronal to the buccal furcation. Anatomic considerations such as this call for judicious management of the osseous crest when performing recontouring procedures so as not to invade the furcation unnecessarily.

Figure 1a Preoperative view of the maxillary left buccal. Figure 1b View of the maxillary left buccal after osseous recontouring. Figure 1c Preoperative view of the maxillary left palatal. Figure 1d View of the maxillary left palatal after osseous recontouring. Figure 2a Preoperative view of the mandibular right buccal. Figure 2b View of the mandibular right buccal after osseous recontouring. Figure 2c Preoperative view of the mandibular right lingual. Figure 2d View of the mandibular right lingual after osseous recontouring.

The palatal and lingual approach to osseous surgery is advocated in the posterior regions due to the location of the buccal furcations, the level of the osseous crest, inclination of the mandibular molars, and the position of infrabony defects.¹⁵ This approach conserves alveolar bone on the buccal aspect, thereby sparing the furcations. While this technique is more time-consuming than others, it helps to prevent the overzealous removal of bone on the buccal aspect and the creation of a negative osseous architecture (Figures 1 and 2).

Becker and colleagues11 compared scaling, osseous surgery, and modified Widman surgery in 16 patients over one year. Each technique was carried out by a periodontist who is a proponent of that technique and is experienced in its application. All patients were diagnosed as having moderate to advanced adult periodontitis. Prior to surgery, each patient had two one-hour sessions of oral hygiene instructions with scaling and root planing. All patients had each of the three procedures performed in different, randomly selected quadrants. After one year, the results showed that scaling, osseous surgery, and the modified Widman procedure were effective in treating moderate to advanced adult periodontitis. However, the greatest increase in 1-3 mm probing depths was found in the osseous surgery group. Sites treated by osseous surgery also had the fewest sites in the 4-6 mm and 7 mm or greater range at the one-year evaluation period. They also found an increase in clinical attachment levels for the 4-6 mm pockets from postsurgery to one year. This increase occurred for all three of the treatment modalities. Kerry and colleagues reported on the results of this study after five years. The five-year results were very similar with regard to probing depths and clinical attachment levels.¹²

Kaldahl and colleagues10 followed 82 patients over two years. Quadrants were randomly assigned to coronal scaling, root planing, Widman surgery, or osseous resection surgery. Initial therapy consisted of coronal scaling in the quadrant that received coronal scaling as the treatment modality. The quadrants designated for root planing or surgery received root planing. At the re-evaluation, additional root planing was completed as needed for the quadrant receiving root planing as the treatment. The areas assigned for surgery had surgery completed as planned. In the quadrants receiving osseous surgery, teeth were extracted and roots amputated to facilitate pocket elimination. Surgery was only performed where pocket depths of 5 mm or greater were present after initial therapy. Results of this study show that probing depth reduction was greater in deeper pockets and greatest for osseous surgery. In 5-6 mm sites, Widman and root planing resulted in a slightly greater gain in clinical attachment levels than osseous surgery, but these gains were similar in pockets greater than 6 mm.

Kahdahl and colleagues18 also reported on the seven-year follow-up of these patients. Of the original 82 patients, 51 were available for follow-up. As was the case with the earlier study, the quadrants treated with flap and osseous resection resulted in greater probing depth reduction in sites that originally demonstrated probing depths greater than 5 mm. All three modes of therapy produced significant and equal gains in clinical attachment levels in sites greater than or equal to 7 mm. However, shallower sites treated by root planing did show slightly better gains in clinical attachment levels than modified Widman and osseous resection.

In a companion study, Kaldahl and colleagues¹⁹ evaluated the incidence of breakdown sites in the above group of patients. If a site lost 3 mm or more of clinical attachment level from three weeks postsurgically or post scaling and root planing, it was classified as a breakdown site. Over the course of the study, the incidence of sites breaking down was greater for deeper sites than for shallow sites. This was true for each of the treatment modalities. Sites treated by osseous surgery, however, did show the lowest incidence of breakdown when compared with the other treatments. This was true for pocket depths in all ranges, i.e., 1-4 mm, 5-6 mm, and greater than or equal to 7 mm.

In 1985, Townsend-Olsen and colleagues¹³ published a follow-up study initiated by Smith and colleagues. They re-evaluated 12 patients with moderate periodontitis who underwent open flap curettage and osseous resection surgery in bilateral quadrants. Both the open flap curettage and osseous resection surgeries were completed by apically positioning the flaps at the osseous crest. Plaque control, root planing, and occlusal adjustment were performed prior to the surgery in all quadrants; and the patients were followed at six-month intervals for the first two years. After two years, the patients were seen every three months until the completion of the study three years later. Probing depths, clinical attachment levels, and sounding to bone were used to measure differences between procedures at the various time points. Plaque index, gingival index, mobility, width of keratinized tissue, and level of the gingival margin were also measured. Results after five years showed that both procedures reduced probing depths initially. However, the osseous surgery quadrants maintained these decreased probing depths to a significantly greater extent than the flap curettage quadrants, especially in the interproximal areas. In addition, the quadrants treated with osseous surgery had significantly fewer sites that bled on probing. In areas that initially demonstrated attachment loss, there was no change from baseline in attachment levels at five years with either procedure.

Recently, Tuan and colleagues20 reported a study comparing the clinical and microbiological study of apically positioned flaps with and without osseous surgery. They evaluated 14 adult periodontitis patients with interproximal craters. In seven patients, osteoplasty and ostectomy were performed from the lingual/palatal aspect to eliminate interproximal osseous defects, and to mimic the original alveolar bony transition to the adjacent teeth. In another seven patients, the surgical flap was adapted to pre-existing osseous defects. Patients were instructed in oral hygiene and were seen on a three-month supportive periodontal therapy schedule. Three periodontal sites having initial depths from 4 to 8 mm were examined at baseline and one, three, and six months. Clinical measurements and subgingival microbiota were evaluated at each examination period. Results showed that pocket depths were reduced more in the group that received osseous recontouring. This was true for the one-, three- and six-month examinations. They also found that in those patients who received osseous recontouring, the levels of subgingival periodontal pathogens were also significantly lower at all examination periods.

Periodontal osseous surgery has been shown to effectively reduce mean probing depth, decrease clinical signs of inflammation, and contribute to the overall stabilization of the clinical attachment. According to the American Academy of Periodontics parameters of care,21 "the goals of periodontal therapy are: to alter or eliminate the microbial etiology and contributing risk factors for periodontitis, thereby arresting the progression of the disease and preserving the dentition in a state of health, comfort, and function with appropriate esthetics, and to prevent the recurrence of periodontitis." Osseous surgery is effective in achieving many of these therapeutic goals. When properly performed, it achieves a physiologic architecture of the marginal alveolar bone that is conducive to gingival flap adaptation and minimal probing depth. The advantages of this surgical modality include the following:

* Produces immediate and predictable reduction in probing depth;

* Improves access for daily oral hygiene and periodic maintenance;

* Preserves gingival width via apically positioned flaps;

* Allows complete removal of granulomatous tissue;

* Allows visualization and access for definitive debridement of radicular surfaces;

* Permits recontouring of bone anomalies (e.g., tori, ledges);

* Allows appropriate access for root resection and hemisection when necessary;

* Permits access for correction of radicular anomalies (e.g., cervical enamel projections, enamel pearls, pin perforations, etc.);

* Facilitates recontouring of restorative overhangs; and

* Permits restorative crown lengthening where indicated.

Figure 3a Preoperative view of the mandibular left lingual showing large lingual tori. Figure 3b View of mandibular left lingual with lingual flap elevated, showing large lingual tori. Figure 3c View of the mandibular left lingual showing osseous recontouring and removal of tori. Figures 4a and 4b The main objective of any periodontal surgical procedure is to the gain access to the root surfaces for more effective removal of calculus and the associated subgingival microbiota.

The advent of osseous surgery for the treatment of early to moderate periodontal disease was spurred by the shortcomings of soft tissue procedures such as gingivectomy and gingivoplasty. These procedures were effective in the short-term reduction of pocket depth and improved access for root debridement, but did so at the expense of the gingival width. Apical positioning of the mucoperiosteal flap during surgery preserves keratinized tissue while achieving a minimal posttreatment probing depth. Bony projections and aberrations such as tori and ledges are often encountered during flap surgery and require osteoplasty to achieve proper adaptation of the gingival flap. Osseous surgery allows for the appropriate access to recontour these anomalies, and achieve minimal sulcus depth wherever possible (Figure 3). This improved access is also beneficial during root resection procedures to access complete removal of the root and allow the creation of a cleansable convex surface.

The difficulty in removing all causative agents from the radicular surface of a tooth has been extensively reported in the periodontal literature.^22-26 Although surgical access does not guarantee definitive instrumentation of the root surface, its effectiveness is greatly enhanced by visualization of the field during debridement. It is not unusual during osseous surgery to encounter a deep fluting or narrow furcation that is laden with calcareous deposits (Figure 4). Osseous surgery permits access to these root features and allows removal of deposits and anomalies such as enamel projections or enamel pearls that encroach upon the furcation and may exacerbate the progression of attachment loss.

The application of osseous surgery to restorative dentistry is also very significant. Today's esthetic procedures demand an even greater attention to the soft tissue margin adjacent to a restoration than ever before. Violation of the biologic width often detracts from the esthetics of a restoration and poses a problem in capturing the impression of the tooth preparation. Osseous surgery achieves a greater axial crown length that aids in retention and creates an appropriate sulcus depth to conceal the restorative margin. In the case of early to moderate periodontitis, the immediate and predictable reduction in probing depths following osseous surgery is reassuring to the restorative dentist, especially when it concerns strategic abutments for a fixed partial denture.

Perhaps the most notable advantage of osseous surgery is the improved access it provides postsurgically for daily oral hygiene and periodic maintenance. Shallower pockets are easier for both the patient and the therapist to maintain. Minimal pocket depths (less than 3 mm) have been shown to be one-fourth as likely as pocket depths greater than 3 mm to show subsequent attachment loss.27 This improved accessibility to the root surface to remove etiologic factors and reduction in pocket depth are consistent with the goal of preventing the recurrence of periodontitis after surgical intervention.

Although endpoints to therapy may differ slightly among the periodontist, restorative dentist, and patient, the advantages of osseous surgery are significant to all. The treatment of periodontal disease often requires the application of several procedures to obtain the intended outcome. Determining factors for success reside in proper clinical diagnosis, appropriate choice and execution of therapies, and the realistic assessment of outcome. It is important to remember that osseous surgery is but one of the several surgical treatment modalities that may be used to treat periodontal disease. Other surgical modalities may be effective when executed properly in the appropriate situation. The European Workshop on Periodontology stated that periodontal therapy using different surgical modalities has been shown to be equally effective in reducing pocket probing depth, controlling the progression of chronic adult periodontitis, and achieving improved levels of probing attachment.²⁸ It may be that the most important factor in successful periodontal therapy is not the therapeutic modality, but the posttreatment maintenance program. However, osseous surgery does remain a viable, time-tested treatment modality that offers a predictable reduction in probing depths, a decrease in gingival inflammation, and a soft tissue form that is conducive to long-term maintenance.

Authors

David F. Levine, DDS, is an assistant clinical professor at the University of Southern California School of Dentistry. He also maintains a private practice in Toluca Lake, Calif.
Greg Filippelli, DDS, is an associate clinical professor at the USC School of Dentistry and attending staff periodontist at the Los Angeles County/USC Medical Center. He also maintains a private practice in Rancho Cucamonga, Calif.

References

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21. American Academy of Periodontology, Parameters of Care. American Academy of Periodontology, Chicago,1996.

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27. Haffajee AD, Socransky SS, et al, Relation of baseline microbial parameters to future periodontal attachment loss. J Clin Periodontol 18:744-50, 1991.

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