TEXT BY THE DEPARTMENT OF PERIODONTICS
UNIVERSITY OF WASHINGTON
(Revised in 2000 by Robert H. Johnson)
Table of Contents
Topography of Alveolar Bone .......................................................................2
Rationale for Osseous Surgery .......................................................................6
Indications for Osseous Surgery ................................................................... 10
Principles of Osseous Surgery ...................................................................... 12
Technique of Osseous Surgery ...................................................................... 14
Healing after Osseous Surgery ...................................................................... 22
Furcation Invasion.......................................................................................... 24
Periodontal Regeneration .............................................................................. 32
Study Questions ............................................................................................. 39
Answers to Study Questions .......................................................................... 42
At the end of the module and course the student given slides, clinical data or drawings
Will be able to distinguish flat gingival architecture from normal.
Will be able to list the reasons bone loss may not be evident radiogaphically.
Will be able to explain why inconsistencies between radiogaphic findings and the pattern
of probing depths can exist.
Will be able to predict and draw the form of the bone (either normal or diseased) on the
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
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.
Will be able to describe in writing the typical post-operative course that a patient would
experience following a segment of osseous surgery.
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.
Will be able to define “furcation invasion”.
Will be able to describe the clinical steps used to identify a furcation invasion.
Will be able to chart furcation invasions on multi-rooted teeth with appropriate symbols.
Will be able to describe three basic classifications of furcation invasions and possible
therapeutic approaches for each.
Will be able to compare and contrast root amputations and hemisections.
Will be able to describe indications and contraindications for root amputations and
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
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.
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
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
marrow resorbs more
quickly than the dense
Bu and Li cortical
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:
Coronal position of the bone margin on the M and D tooth surfaces relative to the CEJ.
Variation in crestal density of interproximal bone.
Presence or absence of vertical (angular) bone defects.
Presence or absence of furcation invasions.
Length and shape of roots.
Crown-root ratio (the extra-alveolar arm of the tooth compared to the intra-alveolar
7. Crown contours, overhanging restorations and deposits of calculus in the interproximal
8. Impacted/missing/tilted/drifted/overerupted teeth.
9. Bony pathoses.
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
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.
As horizontal or vertical bone loss takes place, a variety of bony lesions or configurations result.
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.
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.
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
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
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
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.
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) patient’s 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
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:
Selective extraction and replacement with implants, FPDs or RPDs
Maintenance by periodic closed curettage
Flap debridement followed by maintenance
Regenerative procedures (See later)
Root resections (See later)
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.
VI. TECHNIQUE OF OSSEOUS SURGERY: AN OVERVIEW
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.
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.
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
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
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.
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.
Ramp to Lingual*
Ramp to Buccal*
* Contour the bone to blend the interproximal with the buccal or lingual.
Ramp septum to
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).
Remove buccal and
lingual bone covering
adjacent roots to
reduction on the
adjacent teeth. Note
extension to first
scallops. Gingiva will
tend to follow gradual
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
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
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.
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
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.
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
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.
Frontal Section at Mid-Furca
Embrasures are wider on palatal
aspect, permitting easier access to M
and D furcations which point toward
If detected, the severity should be recorded in the patient’s 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:
C. Indications and Contraindications to Root Resections
In 1969 Basaraba outlined the following indications for root amputations and hemisections:
Uncorrected bone loss involving one root of a mandibular molar, one or two buccal roots
or a palatal root of a maxillary molar.
Furcation invasion such that odontoplasty is not indicated (greater than Class I).
When root proximity prevents proper maintenance.
When osseous recontouring (ostectomy) would cause the exposure of a furcation.
To improve the prognosis of teeth within a fixed bridge.
Fracture of a tooth or root.
Failure of endodontic therapy in one canal and correction or retreatment of this canal is
When recession exposing the entire length of a root cannot be corrected with
His list of contraindications included:
RCT cannot be done on the remaining roots, e.g. partly calcified canal or fused roots.
Bone loss around the remaining roots is too severe to be corrected via periodontal
Class I furcation invasion.
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
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.
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 apicocoronal 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:
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
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.
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.
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
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.
Root Resected with High Speed
Bone and Tooth Recontoured
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
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
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
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 overcontoured.
Occlusal View of Prep
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.
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.
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
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.
Types of Bony Lesions
The walls are needed to contain and nourish the expected growth site.
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.
Prichard’s method focuses on meticulous debridement of the defect. Some clinician’s feel
that additional regeneration potential exists if bone grafts or synthetic materials are added
after the receptor site has been prepared à 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.
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.
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
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
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.
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 ePFTE, 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
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
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.
Amen, C.R.: Hemisection and root amputation. Periodontics, 4:197,1966.
Amsterdam, M. and Rossman, S.R.: Technique of hemisection of multirooted teeth. Alpha
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.,
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,
XI. STUDY QUESTIONS
The crest of the alveolar bone is generally 1-2 mm apical to the coronal margin of the
epithelial attachment in health (T/F)
The underlying bony architecture can be predicted from pocket depth alone. (T/F)
If the gingival architecture is flat, the underlying bone is also flat. (T/F)
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)
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.
A. Horizontal or vertical _____________________
Localized or generalized ___________________
Lingual of first molar
B. Horizontal or vertical _____________________
Type of lesion ___________________________
C. Horizontal or vertical _____________________
Localized or generalized __________________
Type of lesion __________________________
(28 – 29 interproximal)
D. Horizontal or vertical ____________________
Localized or generalized _________________
Type of lesion __________________________
The depth or floor of the interproximal bony crater generally becomes the most coronal
height of the newly created marginal bone. (T/F)
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)
A furcation invasion is an anatomic situation that develops when __________________
exposes the __________________ between separate roots of multirooted teeth.
Treatment is indicated when the patient can’t 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
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 isn’t 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 can’t 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.
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)
Bone regeneration procedures are usually applied to situations where:
____________________ walled lesions exist.
Deep _______________________ lesions exist.
Resective correction ________________________ applicable.
____________________ or maintenance is the only other form of
XII. ANSWERS TO STUDY QUESTIONS
False. We must know what the surface form of the gingiva is like as well.
False. Bony deformities may exist. The probing depths must be recorded before you can
say it's flat.
True - if no bone deformities exist.
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
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.
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".
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.
True, this is how the interproximal septum is formed.
Bone loss, Division (or furca)
Oral hygiene / Plaque control
round diamonds; curets
molar teeth with well-separated roots; caries in the furcation
C and E are indications for root amps/hemisections (A, B and D are contraindications)
endodontic, irreversible pulpitis
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.
Deep three-walled lesions exist, although any three-walled lesion is a candidate
for this procedure.
Generally, regeneration procedures apply to deep localized lesions because
correction by resective means is far too costly to the adjacent teeth.
Where resective correction is not applicable.
Extraction and maintenance are generally the only other forms of therapy