PERIODONTAL SURGERY

MODULE II

OSSEOUS SURGERY

TEXT BY THE DEPARTMENT OF PERIODONTICS

UNIVERSITY OF WASHINGTON

(Revised in 2000 by Robert H. Johnson)

OSSEOUS SURGERY

Table of Contents Page I. Introduction ....................................................................................................1 II. Topography of Alveolar Bone .......................................................................2 III. Rationale for Osseous Surgery .......................................................................6 IV. Indications for Osseous Surgery ................................................................... 10 V. Principles of Osseous Surgery ...................................................................... 12 VI. Technique of Osseous Surgery ...................................................................... 14 VII. Healing after Osseous Surgery ...................................................................... 22 VIII Furcation Invasion.......................................................................................... 24 IX. Periodontal Regeneration .............................................................................. 32 X. Bibliography................................................................................................... 38 XI. Study Questions ............................................................................................. 39 XII. Answers to Study Questions .......................................................................... 42

OBJECTIVES

At the end of the module and course the student given slides, clinical data or drawings

1. Will be able to distinguish flat gingival architecture from normal. 2. Will be able to list the reasons bone loss may not be evident radiogaphically. 3. Will be able to explain why inconsistencies between radiogaphic findings and the pattern

of probing depths can exist. 4. Will be able to predict and draw the form of the bone (either normal or diseased) on the

chart. 5. Will be able to write a paragraph which describes why the bony lesion must be corrected

if pocket reduction is to be achieved. The technical level of this paragraph should be consistent with a professional explanation to a dentist who is unfamiliar with osseous surgery.

6. Will be able to draw the alterations necessary to restore physiologic bone form on a given

drawing showing typical bone loss from periodontitis, and to explain the concept of "gradualization" as it relates to osseous surgery.

7. Will be able to describe in writing the typical post-operative course that a patient would

experience following a segment of osseous surgery. 8. Will be able to explain the physiologic reasons for the symptoms seen during the

post-surgical course, and to suggest a course of management for them. 9. Will be able to define furcation invasion. 10. Will be able to describe the clinical steps used to identify a furcation invasion. 11. Will be able to chart furcation invasions on multi-rooted teeth with appropriate symbols. 12. Will be able to describe three basic classifications of furcation invasions and possible

therapeutic approaches for each. 13. Will be able to compare and contrast root amputations and hemisections. 14. Will be able to describe indications and contraindications for root amputations and

hemisections. 15. Will be able to recognize lesions that are candidates for bone regeneration procedures and

will be able to contrast resective and regenerative procedures as alternate means of therapy.

1

I. INTRODUCTION This module deals with the alveolar bone, as altered by periodontitis, and with the surgical corrections necessary when pocket reduction is desired in the presence of bony deformities. It will review briefly the normal anatomy of bone as it relates to surgery and to the alveolar process. The rationale for surgical correction will be presented along with the theory, technique and general procedure for resective osseous surgery and attempts at regeneration of lost attachment. There also is a section on furcation invasions and the special problems that they impose on the therapist. Module II should be read in conjunction with the information on Internal Bevel Gingivectomy (IBG) and suturing found in Module I.

2

II. TOPOGRAPHY OF THE ALVEOLAR BONE (Predicting Bony Architecture)

Gingival surgery cannot eradicate bony deformities. The problem lies in the bone and until the aberrant topography is corrected by resective or regenerative means, the defects and their resultant increased probing depths will remain. Selection of the correct surgical method for pocket reduction depends, in part, on the type of bony defects present. The detection of bony deformities is made by evaluating the pattern of probing depths and by examining radiographs. A. Pattern of Probing Depths The gingival margin has an innate tendency to follow a scalloped or wave-like configuration regardless of the topography of the underlying bone. In other words the tips of the interdental papillae are situated more coronally than the facial or lingual/palatal height of the marginal gingival. In health the alveolar crest also follows a similar wave-like pattern approximately 2 mm apical to the CEJ. This scalloped configuration is called positive architecture. It is more extreme in the anterior regions of the jawbones than the posterior where it sometimes assumes an almost flat architecture. Negative architecture (a.k.a. reverse architecture) exists when either the gingiva or the bone is destroyed in the interproximal regions resulting in interdental areas being apical to the level of the adjacent facial or lingual/palatal gingiva or bone respectively. This happens infrequently in the gingiva, but can exist in conditions such as NUP/trenchmouth. In bone it is a common finding in periodontitis. In health the bone and gingiva run in parallel waves and probing depths are minimal (1-3mm). In periodontitis interproximal bone typically is resorbed faster than the dense facial or lingual/palatal cortical plates. The uneven rate of resorption creates a crater in the bone or a pattern of negative architecture. Regardless of what happens in the underlying bone, the gingiva maintains its positive architecture with the resultant deepening of interproximal probing depths. Inflammatory swelling of the papillae may cause some of the increased depth; the rest is due to attachment loss of the underlying periodontal supporting tissues.

Resorption occurs at alveolar crest. Once it is destroyed the underlying bone marrow resorbs more quickly than the dense Bu and Li cortical plates.

3

Thus the tooth-to-tooth pattern of pocket depth, probed without anesthesia, provides very useful information for determining the form of the underlying bone. B. Radiographic Appearance Radiographs are a useful supplement to the clinical examination. A good set of radiographs may provide information on:

1. Coronal position of the bone margin on the M and D tooth surfaces relative to the CEJ. 2. Variation in crestal density of interproximal bone. 3. Presence or absence of vertical (angular) bone defects. 4. Presence or absence of furcation invasions. 5. Length and shape of roots. 6. Crown-root ratio (the extra-alveolar arm of the tooth compared to the intra-alveolar

arm). 7. Crown contours, overhanging restorations and deposits of calculus in the interproximal

regions. 8. Impacted/missing/tilted/drifted/overerupted teeth. 9. Bony pathoses.

Radiographic Limitations The main limitation is that the radiograph provides a 2D picture of a 3D object. The dense Bu and Li cortical plates may mask the true extent of an interproximal crater. Superimposition of the roots can hide Bu and Li bone loss. Bone loss from periodontal disease may or may not be evident radiographically. Poor angulation, foreshortened roots, superimposed crowns, and vertical displacement of Bu and Li/Pal cusps can obscure the detection of periodontal defects. On the other hand bone loss may be evident in the radiographs but the probings indicate no increased probing depth. Reasons include inaccurate probings, gingival recession, and/or a "long junctional epithelium". Pattern of Bone Loss Bone loss as seen radiographically can be either in a horizontal or a vertical manner. This loss may be generalized (most teeth in a quadrant are affected) or localized to one or two isolated tooth/teeth. Horizontal bone loss occurs in a direction parallel to the occlusal plane. It may be at different apical levels, but is still roughly parallel to the occlusal plane. Vertical bone loss occurs at an angle to the occlusal plane.

4

As horizontal or vertical bone loss takes place, a variety of bony lesions or configurations result. They include: 1. Interproximal Crater

The interproximal bony crater is the classic form of periodontal defect especially in the posterior regions. Between the dense Bu and Li cortical plates lies a cancellous core that is a vascular lattice-like structure. Once the crestal cortical plate is destroyed by periodontitis, the central bone marrow resorbs more quickly than the Bu and Li cortical plates and an interproximal crater is formed. The boundaries of the crater on the M and D are the roots of the adjacent teeth.

2. Funnel-Shaped Defect The funnel-shaped defect ("well") can occur on any surface of the tooth. It may be

defined as an angular defect with the remaining bone as one wall and the tooth surfaces as the other wall. Comparable to an extreme but local widening of the PDL space, the funnel-shaped defect can involve one or more surfaces of a tooth and a single tooth can display more than one such defect.

5

3. Hemiseptal Defect M or D bone loss involving one tooth but not the adjacent tooth, and

where the Bu and Li interproximal cortical plates are destroyed, results in an angular defect with a rather flat surface from buccal to lingual. In essence it represents a cross between horizontal and vertical bone loss.

6

III. RATIONALE FOR OSSEOUS SURGERY

Periodontitis causes a variable degree of destruction to the marginal alveolar bone, resulting in an irregular, inconsistent bony surface. The eradication of the periodontal pocket depends on the correction of bony deformities and the restoration of physiologic contours to the marginal alveolar bone. In gingivitis the interdental papillae and margins can demonstrate some coronal swelling as part of the inflammatory process. In periodontitis the coronal position of the gingival margin remains essentially unaltered during the disease process, although the gingiva detaches from the tooth as the pocket develops. This behavior reflects an important principle of gingival physiology, that is: The surface form of the gingiva tends to be independent of the surface topography of the underlying bone. Gingiva in health tends to assume gradual, smooth surface contours. These contours are determined primarily by the interrelation of the teeth. Those teeth that are close together will have a prominent gingival papilla that rises high into the contact area. As the space between teeth increases, the height of the papilla decreases until the classical edentulous saddle area is achieved. Gingiva will not assume abrupt rise and fall contours to correspond with the bizarre contours of bony defects that may be present. Thus, the surface contours of the bone exert almost no influence on the surface contour of the gingiva. When interproximal bony craters are formed the gingiva tends to hug the neck of the tooth as though no bony defect exists. This inconsistency is detected clinically as increased probing depth. Thus the success of pocket reduction procedures depends on creating a surface contour of the bone which is essentially an image of the gingival contours. Failure to match bone surface contours to the expected gingival contours will result in recurrent pocket depth as the gingiva matures during the healing process.

7

8

9

10

IV. INDICATIONS FOR OSSEOUS SURGERY

The presence or absence of bony deformities can be determined by evaluating the pattern of periodontal probing measurements and by correlating those data with the radiographic findings. Clinicians often debate the relative value of surgical and non-surgical approaches to periodontal therapy. There also is diversity among those who perform periodontal surgery as to how extensive or radical it should be. A variety of factors impact the feasibility of performing periodontal surgery of any kind. Included in the decision making are the 1) patients age, health and plaque control, 2) probing depths, gingival recession, bone loss, root length, C/R, and tooth mobility, and 3) overall dental treatment plan (i.e., extractions and RPD vs. retention and FPD). Once the decision has been made to proceed with perio surgery, the clinical and radiographic findings influence the selection of the type of procedure. Gingival surgery was covered in Module I. The focus in Module II is periodontal surgery aimed at reducing or eliminating increased probing depths due to bony defects. The principles presented can form the basis for procedures, such as lengthening clinical crowns and placing implants, that may be unrelated to periodontal disease. A. Guidelines The following guidelines are made on the basis that there is an adequate band of gingiva, minimal tooth mobility ( Class I) and no cosmetic restorative implications. 1. Shallow Probing Depths (3-5mm): This usually can be maintained by non-surgical means. 2. Moderate Probing Depths (4-8mm):

This is the classical indication for resective osseous surgery. Attachment loss is moderate and the teeth are tight. The clinician can afford to remove some supporting bone to recreate physiologic contours (positive architecture) albeit at a more apical position. In the compliant patient it is prudent to perform this now rather than wait until there is increased bone loss, probing depths and tooth mobility. Resective osseous surgery is more indicated for situations of generalized horizontal bone loss than for vertical loss in which some teeth display significantly more loss than their neighbors.

3. Deep Probing Depths (9-12mm):

In this situation the destruction is too advanced to correct the bony defects by resective osseous surgery aimed at creating positive architecture. Too much of the supporting apparatus would have to be sacrificed and the teeth in the region would be compromised. This is particularly true if the roots are short and tapered. Alternative approaches are required. They include:

11

a. Selective extraction and replacement with implants, FPDs or RPDs b. Maintenance by periodic closed curettage c. Flap debridement followed by maintenance d. Regenerative procedures (See later) e. Root resections (See later)

12

V. PRINCIPLES OF OSSEOUS SURGERY The correction of bony deformities is based on the need to restore physiologic surface contours to the bone. In health, the interproximal bony septum is more coronal than are the buccal and lingual/palatal marginal bone. In the anterior, the septa tend to be more conical in shape. In the bicuspid and molar regions, the septa are flatter. The surface contours flow smoothly and gradually from tooth to tooth. Deviations from normal occur around teeth situated next to edentulous spaces and diastemas, crowded teeth, and teeth in Bu or Li version. All surgical modifications and corrections are aimed at duplicating normal bone form generally at a more apical level. One-tooth perio surgery is rarely indicated. The correction of a single bony defect is accomplished by removing bone from each side of the lesion until physiologic contours are achieved. The depth of the interproximal crater influences the M and D extent of bone removal. The deeper the lesion, the farther mesially and distally the bone recontouring must be extended to create more gradual contours. Bone contours must be smooth and flow gently from tooth to tooth without precipitous rises or falls in surface contour. The site of the crater also influences the extent of the surgery. It may be possible to deal with a 2mm bony crater between two molars by restricting bone removal to the molars M and D of the defect. If a defect of similar depth is located between two lower incisors, bone removal might have to include at least two teeth on each side of the lesion because these teeth have smaller mesio-distal dimension than do molars. If several teeth in a sextant are periodontally involved, the surgical site will involve at least the whole sextant or even the quadrant. Thus, apical and lateral extensions are carried to points where normal architecture can be reestablished, but at a more apical level. In the following diagram bone loss has occurred on each side of the 2nd premolar. An effort has been made to reestablish smooth and gradual tooth-to-tooth contours by removing bone from the adjacent 1st premolar and 1st molar eliminating the craters and blending the surgical site with the unoperated bony septa to the M and D.

13

14

VI. TECHNIQUE OF OSSEOUS SURGERY: AN OVERVIEW A. Anesthesia Profound block anesthesia of the surgical site. B. Flap Reflection and Debridement Mucoperiosteal ("full-thickness") flaps are raised on the Bu and Li/Pal. Ample flap reflection and relaxation is key! The flap is extended mesiodistally at least one or two teeth on each side of the anticipated site of bone removal. Periosteal elevators or broad surgical curets are used to elevate the flap away from the teeth and apical to the MGJ. Thorough soft tissue debridement and removal of any previously missed calculus is critical. This will lessen bleeding dramatically permitting careful scrutiny of the extent and configuration of the bony craters (See Module I for details of apically positioned mucoperiosteal flap procedure). C. Osseous Recontouring: Start with osteoplasty (removal of non-supporting bone). Long-shanked carbide high-speed surgical burs (#6 or 8 work well) under sterile saline irrigation can be used to reduce and reshape thick bony ledges. Focus on the inter-radicular regions. Here the bone has a cancellous core that can withstand the insult of the procedure. The radicular bone (i.e., that bone on the facial or lingual of the roots) often is thin and without an internal cancellous core reservoir. Unless great care is taken the surgical trauma can lead to irreversible bone loss over the prominence of the roots. The final contours should resemble the festooning seen in a denture. The resultant thinner alveolar housing allows flap placement to assume a more knife-edged margin and helps in the ultimate probing reduction. Moreover the next step ostectomy (resection of supporting bone) is easier to perform when the Bu-Li dimension of the ridge has been decreased.

15

Ostectomy then is performed. The interproximal reduction is accomplished with rotating stones, safe-sided interproximal bone files (such as the Schluger file) and small hand chisels. The depth or floor of the interproximal bony crater generally will become the height of the newly created bony septum. To this end the Bu and Li/Pal marginal bone is resected to a point where it is slightly more apical than the interproximal bone i.e., positive architecture has been formed. To prevent encroachment into furcations, molars can be treated like two premolars. A double smile can be created from the M line angle to the furcation and from this mid-point to the D line angle. Positive architecture is flatter in the posterior region than the anterior.

16

Remove the Bu and Li lips of the crater. The floor of the crater becomes the height of the newly reshaped interproximal bony septum

Create positive architecture by removing Bu and Li cortical bone. To prevent exposure of the furcation regions, remove Bu and Li bone mainly over the roots i.e., treat molars as two premolars.

17

The surface is smoothed, irregularities in the margins are removed with chisels and curets, any residual granulation tissue is curetted away, and the site is irrigated. Any missed calculus is removed.

18

19

Closure is achieved by positioning the flap so that it just covers the bone, and is not hiked coronally onto the teeth. It is the alveolar mucosa of the facial flaps and mandibular Li flap that permits accurate placement. The palatal flap cannot be positioned apically and thus the design of the initial scalloped incision is critical. The fit of the flap can often be improved by contouring and scalloping it around the tooth with scissors. Suturing is completed and the flaps held in position for five (5) minutes to attain hemostasis and a fibrin clot. Dressings are not usually needed unless bone or fibrous connective tissue is left exposed. D. Modifications to Basic Technique

1. Facial/Lingual Craters: Intrabony craters may be located on the facial or lingual/palatal of teeth rather than being restricted to interproximal sites. Depending on the depth and lateral extent of the defects osteoplasty may be all that is needed. Vertical bone height is reduced, but none of the removed bone was supporting bone. Thus an osteoplasty is performed.

2. Combination or Funnel-Shaped Craters: If the facial or lingual crater involves the M or D of the tooth then a resective procedure as described above is performed. Both the depth of the facial or lingual crater and the depth of the interproximal defect dictate the amount of bone which must be removed to create positive architecture.

20

3. Lingual or Buccal Version: The greatest depth of interproximal craters is not always in the mid Bu-Li position, but is located closer to either the Bu or Li cortical plate. Instead of removing an equal amount of the Bu and Li/Pal bony walls, the defect can be ramped to the most involved side. This protects the less involved side of the tooth. Even if the crater is located in the center of the Bu and Li cortical plates it may be advantageous to ramp the defect to the Li/Pal because the furcations are located more apically on that side than on the Bu. More ostectomy therefore can be done without encroaching on the furcation.

Lingual Version Ramp to Lingual*

Buccal Version Ramp to Buccal*

* Contour the bone to blend the interproximal with the buccal or lingual.

Ramp septum to lingual with appropriate lingual ostectomy.

Ramp to buccal

21

4. Vertical Bone Loss: In interproximal vertical bone loss, one of the adjacent teeth can display little, if any, bone loss while its neighbor can have significant attachment loss along the side of its root. A standard approach to osseous resective surgery would require removal of excessive amounts of bone from the non-involved tooth. A recommended modification is to change the abrupt deviation in bony architecture to something that is more gradual. Although classical positive architecture cannot be created the conscientious patient often can maintain the new contours. Narrow vertical defects often are responsive to regenerative techniques (See later).

Vertical deformity (Hemiseptum) mesial molar.

Remove buccal and lingual bone covering adjacent roots to gradualize apical reduction on the adjacent teeth. Note extension to first bicuspid.

Place radicular scallops. Gingiva will tend to follow gradual bone contours.

Vertical Loss

22

VII. HEALING AFTER OSSEOUS SURGERY Osseous surgery may produce more discomfort during the first post-operative week than do other types of perio surgery. This is especially true when bone is not covered by soft tissue. Analgesics should be prescribed for the patient with the usual recommendation to avoid aspirin-containing compounds. Some swelling usually occurs. Swelling after the 5th or 6th day accompanied by pain, a bad taste, and fever should be considered symptoms of infection and treated as such. At 5-7 days the surgical site is cleansed and the sutures removed. The teeth should be lightly curetted to remove debris. Any tags of necrotic tissue should be snipped or curetted free and the area irrigated with warm water. The patient should start gentle cleaning. The patient is seen weekly until the soft tissue achieves a stable position, is free of granulation tissue, shows signs of maturity, and the patient is comfortable and demonstrates that she/he is able to keep the area free of plaque. Studies suggest that frequent prophylaxes after surgery enhance post-operative healing (Nyman, Rosling and Lindhe, 1975). Pocket depth is usually not measured until at least 3 months after the surgery when the active maintenance phase is begun. From the clinician's point of view the most prominent observations during the healing phase of osseous surgery are increased tooth mobility, sensitivity to cold and to biting, and granulation tissue at the flap margin. Underlying these external findings is an interesting healing picture. Exposure of bone results in necrosis of a thin surface layer. This bone is resorbed by the end of the 2nd week; bone apposition is well under way and continues until the 3rd week. Bone remodeling may continue for many months. The soft tissue flap is attached to the bone surface first by a fibrin clot, then by granulation tissue and finally by 1 month post-op, the flap is attached by connective tissue fibers embedded into the new surface bone. Edema and an intense cellular activity in the PDL space explain increased tooth mobility. There is dilation of the PDL blood vessels and resorption of the crestal aspect of the socket bone. Maximum tooth mobility is seen in the 1st 3 weeks and may take many months to resolve (Selipsky, 1976). Dentinal hypersensitivity to cold may occur after periodontal surgery because of the exposure of new root surface to the oral environment. This is especially true if the patient does not practice excellent personal plaque control. Post-surgical necrosis: When bone is exposed, surface necrosis occurs. This happens whether surgery is done on the bone or not. The surface osteoblasts die. The osteoclasts from the underlying marrow spaces move to the surface to remove the dead layer of bone. This layer is very thin, but the amount of

23

bone lost to this "natural" process depends on the conditions of the exposure, e.g., length of time, amount of trauma, drying, etc. Minimizing these factors limits bone loss. The surface necrosis of bone after surgery is almost completely repaired in the interradicular areas because of the presence of underlying marrow, which contains osteoblastic elements. In contrast are the radicular areas where lamina dura often approximates cortical plate in a sandwich without an interposing marrow filling. The source of regeneration, the marrow, is absent, and thus regeneration is limited perhaps 50% will be restored. The clinical implications are that interradicular contours will remain essentially as the surgeon leaves them, not considering the normal remodeling that all bone undergoes. Radicular bone, however, will change form as the result of necrosis. Osteoplasty of radicular bone should be limited because necrosis may result in further thinning and irreversible loss of the radicular bone.

24

VIII. FURCATION INVASION A furcation invasion is a pathological situation, which develops when bone loss exposes the division (furcation) between the roots of multirooted teeth. The gingival margin usually is coronal to the furcation. The narrow opening of the furcation results in restricted access which makes plaque control efforts difficult, if not impossible. Treatment of this problem is undertaken to facilitate oral hygiene, generally by altering the anatomy of the area. A. Classification of Furcation Invasions The greater the exposure of a furcation by bone loss, the less likely treatment will be successful. Accordingly, furcation invasions have been classified by degrees of severity as Class I, II, or III (Easley and Drennan 1969). Class I describes the anatomic situation in which the interradicular fluting (the concavity just coronal to the division between the roots) is exposed but in which the furcation itself is intact. Class II describes the situation in which the bone loss has partially exposed the furcation but is not completely through to the other side. In a Class III, bone loss has resulted in complete exposure of the furcation from one side to another, i.e., - a through & through defect. In a Class III furcation in a maxillary molar only one root may be involved. For example the invasion could enter from the facial and exit the mesial-palatal. An important modification of this basic classification has been made with respect to Class II invasions. The extent of the horizontal invasion is recorded. A Class II furcation invasion with a 2mm horizontal component is not as difficult to treat as is a Class II with 6mm of horizontal breakdown.

X-Sections of Lower Molar at Level Just Apical to Furca

Class I Class II Class III

B. Detection of Furcation Invasions The furcation invasion is detected by passing a curved instrument (pigtail explorer, worn-out curet, Nabers 2N probe) into the sulcus or pocket on the facial and lingua/palatal of all molars and from the mesial or distal of maxillary 1st premolars of the furcation. The objective is to determine if the separation between roots can be felt and, if so, to what degree. A curved instrument is particularly valuable in the detection of distopalatal or mesiopalatal furcations.

25

Frontal Section at Mid-Furca

Class I Class II Class III

If detected, the severity should be recorded in the patients chart. Useful symbols on chartings are

Class I = , Class II = , and Class III = . A helpful modification to this system is to estimate the horizontal component of a Class II furcation in mm (e.g., 3). For example, Class II furcations on the mesial, distal and buccal of #14, are recorded as follows:

Buccal Palatal

Embrasures are wider on palatal aspect, permitting easier access to M and D furcations which point toward the palatal.

26

C. Indications and Contraindications to Root Resections In 1969 Basaraba outlined the following indications for root amputations and hemisections: 1. Uncorrected bone loss involving one root of a mandibular molar, one or two buccal roots

or a palatal root of a maxillary molar. 2. Furcation invasion such that odontoplasty is not indicated (greater than Class I). 3. When root proximity prevents proper maintenance. 4. When osseous recontouring (ostectomy) would cause the exposure of a furcation. 5. To improve the prognosis of teeth within a fixed bridge. 6. Fracture of a tooth or root. 7. Failure of endodontic therapy in one canal and correction or retreatment of this canal is

not possible. 8. When recession exposing the entire length of a root cannot be corrected with

mucogingival procedures.

His list of contraindications included: 1. RCT cannot be done on the remaining roots, e.g. partly calcified canal or fused roots. 2. Bone loss around the remaining roots is too severe to be corrected via periodontal

procedures. 3. Class I furcation invasion. D. Treatment The treatment or correction of a furcation invasion involves one or more of the following procedures: The selection of a procedure is dependent on several factors, including the severity of furcation invasion, amount of remaining bone support, status of abutment teeth, and strategic importance of the involved tooth. Generally, the more severe the invasion, the more involved the therapy.

1. Root Curettage

Incipient furcation invasions (Class I) often require nothing more than periodic rounds of root curettage in order to control inflammation. Generally, this practice works well when the interradicular fluting is broad and access is not a problem.

2. Odontoplasty

This term means, the reshaping of the tooth. With respect to furcation invasions, it means the widening of the furcal area in a buccolingual or mesiodistal as well as apico-coronal direction with a high-speed diamond. For example in a Class I furcation in the lingual of 18, the tooth could be reshaped as follows:

27

X-Section at the Level of the CEJ of #18

The net effect is to widen the inter-radicular area and to remove or reshape the horizontal component of the furcation invasion. The furcation is thus made more accessible for oral hygiene efforts. The initial reshaping is done with round diamonds and is refined with curets.

This procedure is really limited to Class I and shallow Class II furcation invasions. The deeper the invasion, the more reshaping that is required, and thus the more tooth structure that must be removed. Such removal increases the likelihood of dentinal sensitivity, which can be so severe that root canal therapy is required.

3. Osteoplasty

If the fluting is narrow or there is restricted access to the furcation, osteoplasty/odontoplasty procedures may be necessary. The tooth and alveolar bone in the furcation area are reshaped. The elimination of bony ledges and the placement of vertical grooves" in the bone just coronal to the furcation make the contours more gradual in an apical-coronal direction, which improves access for home care devices and curets. This technique is generally employed as part of a segment of periodontal surgery, and is not often used alone.

28

4. Root Resection

Root resections (amputations) are utilized when the furcation invasion is too advanced to be corrected by the previous techniques. Access to the furcation can be gained by removing one or more of the affected roots.

X-Sections of Upper Molar Just Apical to Furcation

Mesial-buccal root removed Osteplasty completed

A flap is reflected to expose the underlying bone. The bony plate covering the involved root is removed to about 2/3rds of its length. A bur is used to cut through the root to be removed. This cut is apical to the opening of the furcation. Once resected, the root is extracted. The remaining stump is contoured to smooth out any sharp angles and to remove any undercuts. This is critical so the restorative dentist can prepare the tooth for the eventual crown. If endodontic therapy has not been previously performed, ZOE is placed into the opening to the canal.

Flap Reflected Root Exposed Root Resected with High Speed

Root Extracted Bone and Tooth Recontoured

5. Hemisection

In a hemisection the tooth is cut in half. The technique is used virtually exclusively on mandibular molars to treat Class II or III furcation invasions. The tooth is sectioned from buccal to lingual, parallel to a line joining the buccal and lingual furcas. In contrast to

29

root amputations, extraction of one of the sections does not necessarily need to be performed. For example, if No. 19 has a Class III furcal invasion and each root still has adequate bone support, the tooth can be divided in half and each half treated as a separate premolar. Access to the furcation is now gained though the new embrasure area.

A hemisection often will be followed by the extraction of one of the sectioned halves. This is done primarily when the severe attachment loss is restricted to one root, the other root can be treated, and there is no other stable distal abutment.

A bur (high-speed) is used to cut through the coronal portion of the tooth separating it into two halves. It is advisable to make the coronal cut prior to flap reflection to minimize the amount of tooth structure and restorative material that gets into the surgical site.

Root amputations or hemisections almost always result in irreversible pulpal damage that demands endodontic therapy. Ideally the endo is done first which ensures patient comfort. Sometimes the decision to do a root resection cannot be made until flaps have been reflected and the periodontal status has been carefully assessed. The RCT must be delayed until after the resection. Regardless of the sequence, consultation with both endodontist and periodontist is required to ensure both aspects of the treatment can be performed.

Thus the strategic importance of the involved tooth should be carefully assessed prior to commencing either a root amputation or hemisection. Is it better to extract the tooth and replace it with a FPD or an implant or is it better to proceed with the root resection? The procedures involved in a hemisection are expensive. They include the cost of the surgery, root canal therapy on the remaining root, and a crown. Furthermore after the removal of half of a mandibular molar an edentulous space is created that may require the construction of a FPD. However, if the involved tooth is a 1st molar and the terminal tooth in the arch, its retention may be far more critical than if it were a 1st molar with adjacent solid 2nd molar and 2nd premolar.

The principles of crown preparation remain whether or not a tooth has had a root amputation. There must be sufficient reduction for draw without compromising

30

retention, and the preparation must terminate on solid tooth structure. The completed prep looks quite different from a typical crown prep. Undercuts that remain in the area of the root amputation must be removed. A full occlusal table would be waxed in with a gradual occlusal-apical contour in the area of the root amp so that the crown is not over-contoured.

Occlusal View of Prep Occlusal

Langer et al, made a 10-year evaluation of root resections. Of 100 teeth so treated, 38 had failed by the end of 10 years. Interestingly although the primary reason for performing the root resections was to treat periodontal lesions, most of the failures (28 of 38) were due to endodontic or restorative problems such as root fractures, cemental washouts, caries, and recurrent periapical pathoses. Mandibular molars failed twice as often as did maxillary molars. On a more positive note 62% of the cases did last a decade.

6. Tunneling

The tunneling procedure has been used in Class III furcation inversions. A flap is reflected, ostectomy and osteoplasty usually are required, and the flap is sutured in an apical position exposing the furcation to the oral cavity so that it is accessible for oral hygiene measures. This is generally limited to molar teeth with well-separated roots. Roots in close proximity are not good candidates because of the difficulty in obtaining access for plaque control.

The tunneling procedure is not done frequently. Caries may develop because of the difficulty in removing plaque from the furcal roof which often is concave. Interproximal brushes dipped in fluoride and irrigation using a Mono-Jet syringe and chlorhexidine may help to slow caries activity.

31

7. Regeneration

Regeneration procedures designed to recreate lost periodontal attachment have not been particularly rewarding especially in furcation invasions. Recent interest has focused on guided tissue regeneration in the treatment of Class II & III defects. In this technique, full-thickness flaps are reflected, the areas are thoroughly debrided, and a synthetic membrane or other material is placed over the bony defect. The actual defect may or may not be filled with freeze-dried bone prior to the placement of the membrane. The theory behind this technique is that regeneration of the attachment apparatus may occur if cells from the PDL are allowed to repopulate the affected root surfaces. The membrane serves as a barrier and excludes gingival connective and epithelium tissues from the healing process. It is hoped that a true new attachment of bone, ligament, and cementum will result.

32

IX. PERIODONTAL REGENERATION Regeneration is the reproduction or reconstitution of a lost or injured part. Repair is the healing of a wound by tissue that does not fully restore the architecture or the function of the part. In periodontal regeneration there is a restoration of the lost periodontium i.e., new bone, ligament and cementum all attached in a functional arrangement. Often bone is formed but a long junctional epithelium migrates apically between it and the root surface thus preventing the formation of a true new attachment. Resective osseous surgery is a means of correcting bony deformities by removing bone. Ideally periodontal therapy should be designed to regenerate lost attachment. Not an easy task, numerous materials and techniques have been tried. Factors that may dictate success rates include the dimensions of and the number of bony wells making up the periodontal defect. In general the narrower the defect and the greater number of bony walls of the defect, the greater the chance of regeneration. The walls are needed to contain and nourish the expected growth site. A four-wall bony defect is an extraction socket, which will fill with bone. A three-wall defect has 3 bony walls; the 4th wall is the tooth root. The common interproximal defect usually consists of 2 bony walls i.e., the buccal and lingual cortical plates the remaining 2 walls are the roots of the adjacent teeth. The configurations can vary; examples are seen in the accompanying diagram.

33

Types of Bony Lesions

The walls are needed to contain and nourish the expected growth site.

34

A. Flap Debridement

1. Prichard Technique A type of flap curettage, this procedure is best suited to three-wall bony deformities. Full-thickness flaps are elevated on both buccal and lingual. All granulation tissue is removed from all walls of the bony lesion and the bone and tooth are meticulously curetted. Some clinicians perforate the walls of the lesion with small round burs to allow migration of osteogenic elements from the adjacent marrow spaces.

In Prichard's technique when the flaps are replaced and sutured, the marginal bone is left denuded. The rationale is that it may take longer for the surface epithelium to migrate into the defect thus providing time for coronal regeneration to take place. Some therapists place the patient on antibiotics.

Healing, if successful, occurs when bone is regenerated from the floor and walls of the lesion to fill the defect. Care is taken to ensure that the tooth is not in traumatic occlusion. This procedure is considered to be predictable by some and unpredictable by others. Where a localized lesion exists and the alternative is extraction, an attempt at regeneration is clearly indicated. Resective surgery may be too destructive to adjacent teeth and extraction may demand an implant, a FPD or a RPD.

B. Grafts

Prichards method focuses on meticulous debridement of the defect. Some clinicians feel that additional regeneration potential exists if bone grafts or synthetic materials are added after the receptor site has been prepared la Prichard. 1. Autografts/Autogenous Grafts

An autograft refers to tissue transferred from one position to another within the same individual. The graft can be harvested from an intraoral or extraoral site.

a. Intraoral: Alveolar bone marrow, shavings of marrow and cortical bone, or a slurry of ground bone, blood and saliva called "osseous coagulum", have all been used in an effort to stimulate regeneration.

Bone marrow is considered desirable because of the larger number of cells available for regeneration. Unfortunately good donor sites are difficult to find in the oral cavity. Nevertheless an adjacent site of osseous surgery may provide osseous coagulum for localized uncorrectable lesions. An edentulous area nearby or a tuberosity may offer a good supply of donor bone. An 8 to a 10-week-old extraction socket often is the source of bone with good osteoblastic potential. The chin also has been used.

35

The results of this type of regenerative procedure vary depending on case selection and the clinician. Some feel that in the three-wall and similar type of lesions, a 50% repair of the depth is in order. If this occurs, a second graft may be indicated or the lesion may now fall within the range of those correctable by resective reshaping.

b. Extraoral: The anterior iliac crest is a good source of marrow and cancellous bone, but does demand a second procedure usually performed by a hematologist in the operating room. New bone formation can occur in the periodontal defect, but not without a possible price. A fresh autogenous extraoral bone graft can cause root resorption. This does not occur when an intraoral source is used or if the extraoral autograft is frozen prior to placement in the periodontal defect. New bone may be produced using this source, but that does not mean that it is attached to the tooth root via a functional PDL.

2. Allografts/Homografts

An allograft is a graft between genetically dissimilar members of the same species. Sterilized freeze-dry bone and decorticated freeze-dry bone are readily available from a number of reputable organizations including The American Red Cross. Gamma irradiation of the total donor (a cadaver within 12 - 24 hours of death) eliminates surface contaminates and the use of ethylene oxide destroys any possible HIV or hepatitis. Some clinics mix the harvested bone with tetracycline in the hope of increasing regeneration potential.

3. Heterografts/Xenografts

These grafts are taken from a donor of another species, such as cattle (bovine bone).

4. Synthetic Grafts

A variety of bioceramic materials (hydroxyapatite or tricalcium phosphate) have been used in recent years as grafts. Some are resorbed; others remain as inert fillers in the periodontal defects. There is no convincing evidence that these synthetic graft materials induce new bone or periodontal ligament formation, provide tooth support, or prevent epithelial downgrowth.

C. Guided Tissue Regeneration (GTR) Barrier membranes have been introduced to eliminate the influence of unwanted cells and permit those with regenerative properties to proliferate and contact the denuded root. Some membranes are resorbable; some are not and demand a 2nd surgical procedure to remove them. W.L. Gore and Associates has designed expanded polytetrafluorethylene (e-PTFE), a Teflon material marketed as GORE-TEX Periodontal Material (R). The material is non-resorbable. According to biological principles 4 tissue types (epithelium, gingival connective tissue, alveolar bone and periodontal ligament) compete for the space adjacent to the tooth root after surgery.

36

Without interference epithelium usually wins the race, forming a long junctional epithelium. In the barrier technique full-thickness mucogingival flaps are reflected, the defects and roots carefully debrided, and the e-PTFE is sutured, apron-like, around the neck of the involved tooth and over the alveolar bone. The flaps are sutured over the top of the material, which is left in place for 6 weeks or longer. The material keeps the epithelium and gingival CT away from the space allowing the PDL and bone cells to populate the site and theoretically create a true new attachment. Sometimes the material is used with a grafted material such as DFDBA. Results are mixed. Smashing successes have been documented, failures are plentiful. The material per se is expensive and the surgical procedures costly. Unfortunately the procedure is not reliable. Manufacturers of bioresorbable barriers make similar claims of significant gain of clinical attachment without the need of a 2nd procedure to remove the material. The matrix resorbs in 6 to 8 weeks. Results are promising in some patients, disappointing in others. D. Ridge Augmentation Destroyed or resorbed alveolar ridges often compromise the functional/cosmetic results of FPDs and limit the success of endosseous implants. A series of surgical innovations using intraoral soft tissue grafts, bony autogenous and allogenic grafts, and synthetic materials have been attempted to increase the buccal-lingual dimension and vertical height of the alveolar ridge. Therapeutic goals are seldom met in full. GORE-TEX Augmentation Material (GTAM) has shown some promise when used to expand the dimensions of the alveolar ridge and cover dehiscences over roots or implants. Constructed of e-PFTE, it can be used with freeze-dry bone in a tent-like configuration to create space over the deficiency. Its main limitation is the cost of the actual material and the two surgical procedures. Nevertheless the potential rewards may be worth the price. E. Summary of Regeneration Three-walled lesions have the best prognosis for periodontal regeneration, regardless of the procedure. Case selection may be critical, and meticulous debridement and root preparation is essential. Regeneration procedures are most indicated for deep localized lesions adjacent to less involved areas; where resective correction is not feasible and where difficult maintenance of the lesion or removal of the tooth may be the only other alternatives. Partial success of a regeneration procedure may then allow resective correction of the remaining lesion. The donor bone does not survive and grow, but serves as a stimulus or nidus for new bone growth within the lesion. One of the problems that may be associated with fresh hip marrow grafts is that of root resorption.

37

Synthetic materials may act as fillers or as a latticework for bone growth into a void. Depending on the lesion, new bone growth often occurs but a true new attachment is difficult to achieve. A long epithelial attachment frequently is found between the new bone and the root. GTR is an exciting new avenue of treatment. Although successes can be dramatic, the procedure is not consistently reliable and is expensive.

38

X. BIBLIOGRAPHY Amen, C.R.: Hemisection and root amputation. Periodontics, 4:197,1966. Amsterdam, M. and Rossman, S.R.: Technique of hemisection of multirooted teeth. Alpha Omegan, 53:4,1960. Basaraba, N.: Root amputation and tooth hemisection. D.C.N.A., 13:121,1969. Easley, J.R. and Drennan, G.A.: Morphological classification of the furca. J. Can. Dent. Assoc., 35:104,1969. Farrar, J.N.: Radical and heroic treatment of alveolar abscess by amputation of roots of teeth. Dental Cosmos, 26:79,1884. Goldman, H.M.: Therapy of the incipient bifurcation involvement. J. Periodontol, 29:112,1958. Hamp, S.E., Nyman, S. and Lindhe, J.: Periodontal treatment of multirooted teeth. (Results after 5 years). J. Clin.. Periodontol, 7:126,1975. Langer, B., Stein, S.D. and Wagenberg, B.: An evaluation of root resections. J. Periodontol, 52:719,1981. Nyman, S. and Lindhe, J.: Considerations in the treatment of patients with multiple teeth with furcation involvements. J. Clin. Periodontol, 3:4,1976. Nyman, S., Rosling, B. and Lindhe, J.: Effect of professional tooth cleaning on healing after periodontal surgery. J. Clin. Periodontol, 2:80,1975. Pontoriero, R., Nyman, S., Lindhe, J., Rosenberg, E. and Sanavi, F.: Guided tissue regeneration in the treatment of furcation defects in man. J. Clin. Periodontol, 14:618,1986. Selipsky, H.: Osseous surgery how much need we compromise? Dent Clin North Am, 20:79,1976.

39

XI. STUDY QUESTIONS 1. The crest of the alveolar bone is generally 1-2 mm apical to the coronal margin of the

epithelial attachment in health (T/F) 2. The underlying bony architecture can be predicted from pocket depth alone. (T/F) 3. If the gingival architecture is flat, the underlying bone is also flat. (T/F) 4. A gingivectomy procedure is the procedure of choice to eliminate soft tissue pockets,

provided there is an adequate band of gingiva with which to work. (T/F) 5. Identify the type of bone loss (horizontal or vertical) and/or the type of lesion shown

(funnel- shaped, crater or hemiseptal defect) in the drawings below.

Lingual of first molar

(28 29 interproximal)

A. Horizontal or vertical _____________________ Localized or generalized ___________________

B. Horizontal or vertical _____________________ Type of lesion ___________________________

C. Horizontal or vertical _____________________ Localized or generalized __________________ Type of lesion __________________________

D. Horizontal or vertical ____________________ Localized or generalized _________________ Type of lesion __________________________

40

6. The depth or floor of the interproximal bony crater generally becomes the most coronal height of the newly created marginal bone. (T/F)

7. When the walls of the crater have been removed, physiologic architecture is established

by removing Bu and Li/Pal bone from the teeth, which in effect creates a new interproximal bony septum. (T/F)

8. A furcation invasion is an anatomic situation that develops when __________________

exposes the __________________ between separate roots of multirooted teeth. 9. Treatment is indicated when the patient cant maintain adequate

_______________________ in the exposed furcation. 10. The more the furcation is exposed by bone loss, the more/less (circle best answer) likely

treatment will be successful. 11. Maxillary mesial furcations are best reached by passing a curved instrument from the

buccal/palatal around the mesial curvature of the mesial/palatal root (circle best answer). 12. If the furcation invasion is Class II or Class III, odontoplasty procedures may result in

________________________________________ and should therefore not be done. 13. A hemisection can be used to treat Class II or Class III furcation invasions on

________________________________________. 14. In performing an odontoplasty, initial reshaping is done with _______________________

and is refined with ______________________. 15. Tunneling exposes the furcation to the oral cavity so that it is accessible for oral hygiene

measures. It is generally limited to __________________________________________, and if adequate plaque removal isnt maintained _______________________ may result.

16. Identify the following indications for root amps/hemisections by circling the number

opposite the correct sentences. A. Class I or less furcal invasion. B. RCT cant be done on the remaining roots. C. Fractures of the tooth or root. D. Uncorrectable bone loss involving the remaining roots. E. When root proximity prevents proper maintenance. 17. If possible, root amputations should be preceded by _______________ therapy, as

__________________________________________ can occur.

41

18. Bone regeneration procedures have the best chance of success in ___________________ wall defects. Three-wall defects have a fourth wall, which is the tooth and three walls, which are bone (T or F) ___________. Bone regeneration procedures include those where the lesion is simply cleansed out and the flap replaced (Prichard Technique), and those where marrow, bone chips and os-coagulum are used (T or F) ________________________________

19. Bone regeneration procedures are usually applied to situations where: A. ____________________ walled lesions exist. B. Deep _______________________ lesions exist. C. Resective correction ________________________ applicable. (is/is not) D. ____________________ or maintenance is the only other form of available therapy.

42

XII. ANSWERS TO STUDY QUESTIONS 1. True. 2. False. We must know what the surface form of the gingiva is like as well. 3. False. Bony deformities may exist. The probing depths must be recorded before you can

say it's flat. 4. True - if no bone deformities exist. 5.

A. There is moderate generalized horizontal bone loss in this area. Note the wide PDL space around #22, a possible indication of tooth mobility perhaps as a result of trauma.

B. Bone loss is vertical. The funnel-like defect exposes the lingual of the first molar and its furcation. Note the torus and the thick buccal and lingual plates, both of

which make cleaning difficult.

C. There is vertical loss resulting in a hemiseptum (half a septum). These lesions often result from trauma or of some severe local irritation. A tooth tipped to the mesial into an edentulous space can create the radiographic appearance of a hemiseptal defect. Uprighting the tooth may eliminate the "defect".

D. This is a view of a 'normal'. The height of the bone is in a normal position but

there may be slight widening of PDL space on the mesial of #29. It does not represent vertical bone loss but rather inconsistent levels of adjacent CEJs.

6. True 7. True, this is how the interproximal septum is formed.

8. Bone loss, Division (or furca)

9. Oral hygiene / Plaque control

10. Less 11. palatal, palatal 12. root sensitivity 13. mandibular molars 14. round diamonds; curets

43

15. molar teeth with well-separated roots; caries in the furcation 16. C and E are indications for root amps/hemisections (A, B and D are contraindications) 17. endodontic, irreversible pulpitis 18. Bone regeneration procedures have the best chance of success in 3-walled defects. The

more bony walls, the better. It is true that three-wall defects have a fourth wall, which is the tooth. The statement, which follows, is true.

19. A. Deep three-walled lesions exist, although any three-walled lesion is a candidate

for this procedure. B. Generally, regeneration procedures apply to deep localized lesions because

correction by resective means is far too costly to the adjacent teeth. C. Where resective correction is not applicable. D. Extraction and maintenance are generally the only other forms of therapy

available.

Table of ContentsObjectivesIntroductionTopography of the alveolar boneRationale for osseous surgeryIndications for osseous surgeryPrinciples of osseous surgeryTechnique of osseous surgery: an overviewHealing after osseous surgeryFurcation invasionPeriodontal regenerationBibliographyStudy questionsAnswers to study questions