Jan Lindhe. Clinical Periodontology

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TREATMENT

FURCATION-INVOLVED

TEETH • 715

Fig. 29-20. Tunnel preparation of a degree III-involved mandibular molar. Radiograph (a) and photograph (b)

showing a wide interradicular space where self-performed plaque control can be obtained by the use of an inter

proximal brush.

Fig. 29-21. Effect of orthodontic treatment of a separated mandibular molar with a small root divergence. (a) After

root separation. (b) 3 months after completion of orthodontic therapy

ino 1980). A tooth with a short root trunk is a good

candidate for RSR; the amount of remaining periodon-

tal tissue support following separation and resection

often sufficient to ensure the stability of the remaining

root cone. If the root trunk

is long,

the furcation

involvement occurs later in the disease process, but

once established the amount of periodontal tissue

support left apical of the furcation may be insufficient

to allow RSR.

The divergence between the root cones

The distance between the root cones must be consid-

ered. Roots with a short divergence are technically

more difficult to separate than roots which are wide

apart. In addition, the smaller the divergence is, the

smaller also is the interradicular (furcation) space. In

cases where the divergence between two roots is

small,

the possibility of increasing the interradicular

distance

with an orthodontic root movement may be

considered

(Fig. 29-21a,b).

The furcation space may also be increased by odon-

toplasty performed during surgery. Fig. 29-22a-c illus-

trates that

odontoplasty

was performed on (1) the distal

part of the mesial root and (2) the mesial part of the

distal root and deep finishing lines prepared for the

subsequent restoration (Di Febo et al. 1985).

The length and the shape of the root cones

Short and small root cones (Fig. 29-23) following sepa-

ration tend to exhibit an increased mobility. Such

roots, in addition, have narrow root canals which are

difficult to ream. Short and small roots consequently

should be regarded as poor abutments for prosthetic

restorations.

Fusion between root cones

When a decision has been made to perform RSR, it is

important that the clinician first determines that the

cones within the root complex are not fused. This is

generally an uncomplicated diagnostic problem for

716 • CHAPTER 29

Fig. 29-22. Odontoplasty of a separated mandibular molar performed during surgery to increase the furcation

space. After flap elevation and exposure of the alveolar bone, it is evident that the distance between the two roots is

small (a). By preparing the interradicular surfaces during surgery (b) the furcation space is increased and is suffi

cient for self-performed plaque control measures (c).

Fig. 29-23. Radiograph showing maxillary molars with

thin, short and conical roots.

Fig. 29-24. Radiograph indicating the presence of a de

gree III involvement of the buccal furcation of the max

illary first molar. This tooth is a candidate for root re-

section.

mandibular molars or for the buccal furcation of max- raised to allow the operator to get proper access to the

illary molars (Fig.

29-24).

At such teeth the separation approximal tooth surfaces. The mesial (or distal) en-area

between the roots can easily be identified both trance of the furcation must be probed to a depth of with the

probe and in a radiograph. It is more difficult 3-5 mm to ascertain that a fusion does NOT exist

to identify a

separation line between mesiobuccal (or between the roots scheduled for RSR.

distobuccal) and palatal roots of a maxillary molar or

maxillary first premolar with a narrow root complex.

In such situations, a soft tissue flap must often be

TREATMENT

FURCATION-INVOLVED TEETH •

Table 29-1. Root resective treatment possibilities in molars with furcation involvement

Furcation involvement

Root resection

Root resection plus separation

of the remaining roots

Buccal

Mesial

Distal

Mesiobuccal, Distobuccal

Mesiobuccal, Palatal

Distobuccal, Palatal

Buccal & Distal

Buccal & Mesial

Mesial & Distal

Distobuccal, Mesiobuccal & Palatal

Mesiobuccal, Distobuccal & Palatal

Palatal, Mesial & Distobuccal

Palatal

Palatal, Distobuccal

Distobuccal

Buccal, Distal & Mesial

Distobuccal & Palatal, Mesiobuccal

& Palatal, Mesio & Distobuccal

Palatal, Distobuccal

Fig. 29-25. Occlusal view of a restoration using the

mesial root of a maxillary first molar as abutment.

Note the alignment of the mesial root and the adjacent

premolars.

Amount of remaining

support around individual

roots

This should be determined by probing the entire cir-

cumference of the separated roots. It should be ob-

served that a localized deep attachment loss at one

surface of one particular root (e.g. on the buccal sur-

face of the palatal root, or the distal surface of the

mesiobuccal root of a maxillary molar) may compro-

mise the long-term prognosis for an otherwise ideal

root.

Stability

of individual roots

Must be examined following root separation. Rule of

thumb: the more mobile the root cone is, the less

periodontal tissue support remains.

Access for oral hygiene devices

The site must after completion of therapy have an

anatomy which facilitates proper self-performed

toothcleaning.

Maxillary molars

General example

Several decisions must be made when RSR is planned

for a furcation-involved maxillary molar. Since such

teeth have three root cones, one or two cones may be

retained after separation. Different treatment alterna-

tives exist. They are listed in Table 29-1.

Prior to RSR, the morphology of the individual

roots as well as the surface area of each root must be

carefully analyzed.

The

distobuccal root

of a maxillary molar (1) is the

shortest of the three roots; (2) the root trunk is com-

paratively long. Thus, the distal root has a small quan

tity of bone support and once separated, the cone may

exhibit increased mobility. The distobuccal root is,

therefore, often removed as part of RSR (Rosenberg

1978, Ross & Thompson 1980).

The

mesiobuccal root

has (1) a wide buccopalatal

dimension, (2) an hour-glass cross section, and there

fore a large root surface area. In fact, the mesiobuccal

cone often has a total root surface area that is equal to

or greater than that of the palatal root cone. The

mesiobuccal root (1) is located centrally in the alveolar

process, (2) is properly aligned with the maxillary

premolars and is in an ideal position to function as a

separate unit (Fig. 29-25). For these reasons, the mes

iobuccal root may be preferred for retention when the

clinician is selecting between the mesiobuccal or pala

tal root. It should be remembered, however, that the

root canals of the mesiobuccal root are narrow and

more difficult to treat than the single and wide canal

of the palatal root.

The tissue destruction in the furcation area often

causes deep attachment and bone loss at the distal-

718 • CHAPTER 29

Fig. 29-26. Palatal root of a root-resected maxillary molar serving as a single abutment for a crown restoration (a). A

mesiobuccal root was included in the restoration for esthetic reasons (b).

Fig. 29-27. The sequential stages of root resection of two maxillary molars with degree III involvement. Radiograph

showing the pre RSR situation (a). The roots were separated before flap elevation (b). The distal roots of both mo

lars

and the palatal root of the first molar were extracted and the teeth prepared (c,d). After 3 months of healing (e).

The

final prosthetic restoration of the site (f).

TREATMENT OF FURCATION-INVOLVED TEETH •

719

Fig. 29-28. Resection of the dis

tobuccal root of a three-rooted

maxillary first premolar.

palatal surface of the mesiobuccal root. In such situ-

ations the palatal root remains as the only candidate

for retention (Fig. 29-26a,b).

The series of illustrations presented in Fig. 29-27

demonstrates two left maxillary molars (teeth 26 and

27) with degree III involvement of all six furcation

entrances. Both teeth were, following a detailed ex-

amination and diagnosis, scheduled for treatment

with RSR. Note that in this case the second premolar

was missing. In cases of advanced periodontal disease

at maxillary molars, it is often necessary to separate

all three roots of the individual tooth to obtain access

to the interradicular area for assessment of the height

of the remaining bone at (1) the buccal surface of the

palatal root and (2) the palatal surfaces of the buccal

roots. Fig. 29-27b illustrates the two maxillary molars

with all six roots separated. Because of anatomic con

siderations and increased mobility, the distobuccal

roots of 26 and 27 were extracted (Fig. 29-27c). The

palatal root of the first molar had a deep area of

localized attachment loss on its buccal surface, was

considered to be a poor candidate for a bridge abut-

ment and was extracted. The mesiobuccal root of the

first molar as well as the mesiobuccal and palatal roots

of the second molar (27) were stable and exhibited

moderate probing depth. It was anticipated that at all

three roots the anatomy following healing after treat-

ment would allow proper plaque control. The three

roots were maintained (Fig. 29-27d). Fig. 29-27e shows

the area after 3 months' healing and Fig. 29-27f illus-

trates the segment properly restored. Since in this

segment one premolar was missing, the mesiobuccal

root of the first molar was used as second premolar in

the prosthetic reconstruction and the two roots of the

second molar served as abutments for a crown resto-

ration in the position of a molar.

Maxillary premolars

Root resection of maxillary first premolars is possible

only in rare instances due to the anatomy of the root

complex (Joseph et al. 1996) (Fig. 29-28a,b). The furca

tion of this premolar is often located at such an apical

level that the maintenance of one root serves no mean

ingful purpose. In most cases, therefore, the presence

Fig. 29-29. Results of the root resection of a mandibular

first molar of which the distal root was retained.

of a deep furcation involvement of degree II or degree

III in a maxillary first premolar calls for tooth extrac-

tion.

Mandibular molars

If RSR must be applied in a furcation-involved

mandibular molar, three treatment alternatives exist:

separate the two roots, but maintain both roots

(

premolarization)

separate and extract the mesial root

separate and extract the distal root

In some situations, both roots may be maintained

following separation.

If one root is to be removed, the following facts

must be considered:

The

mesial

root has a significantly greater root sur-

face area than the distal root. The mesial root, how-

ever, has an hour-glass-shaped cross section which

may be difficult to manage (1) in the self-performed

plaque control and (2) in the restorative procedure. In

addition, the mesial root frequently has two narrow

root canals. The root canals are often close to the

external root surface. This may complicate root prepa

ration during the subsequent restorative treatment.

The

distal

root has an oval cross section and, as a

rule, only one, wide root canal. The distal root (1) is

720 • CHAPTER 29

Fig. 29-30. Combined photograph and radiograph showing the "conservativ

approach both regarding the access

to the pulp chamber (a) and the shaping and filling of the root canal system (b). Schematic illustration showing the

temporary restoration of the endodontically treated tooth (c).

Fig. 29-31. Radiograph illustrating the damage which

occurred to the interradicular septum during root sepa

ration.

comparatively large, providing a greater mass of

dentin to resist root fracture (Langer et al. 1981); (2) is

a good candidate for pin or post placement. Further,

when the resected mandibular molar is a terminal

abutment for a bridge, the retention of the distal root

will result in a longer dental arch than would be the

case had the mesial root been retained (Fig. 29-29).

Sequence of treatment at RSR

Once anatomic and pathologic characteristics of the

root complex (es) of multirooted teeth have been docu

mented, treatment should follow a logical plan (see

also Chapter 19).

Endodontic

treatment

If the tooth to be resected is vital or if an improper root

canal filling was placed in a non-vital tooth, RSR starts

with endodontic therapy. Rubber dam can be placed,

and optimal conditions thus be established for the

important management (cleaning and shaping) of the

root canal. The structural integrity of the root must be

maintained and minimal amounts of root dentin

should be removed (Fig. 29-30a,b). Direct filling with

amalgam or chemically cured composite of the endo-

dontically treated tooth should be performed before

RSR (Fig. 29-30c). Each root should have individual

retention for a restoration which should not break or

detach during RSR, removal and relining of the pro-

visional restorations, impressions and prosthetic trys

in. Endocanal posts or endodontic screws are used

only if natural retention needs improvement.

Occasionally, a furcation involvement may first be

identified during periodontal surgery. In this emer-

gency situation RSR may be completed but the root

canal entrance(s) of the remaining root(s) must be

properly sealed. Definitive root canal therapy must be

completed within two weeks (Smukler & Tagger

1976)

Provisional restoration

Alginate impressions of the area to be treated are taken

and sent to the laboratory together with a wax record

of the intercuspal position. A provisional restoration

is prepared.

RSR

Root separation and root resection may be performed

as part of the preparation of the segment for prosthetic

rehabilitation ("prosthetic preparation"), i.e. prior to

periodontal surgery (Carnevale et al. 1981). During

the prosthetic preparation it is important to

avoid

•

exposing the interradicular bone to undue

mechani

cal trauma (Fig. 29-31)

•

leaving behind parts of the furcation fornix (Fig. 29-

32a-d)

•

perforating the root canals

•

preparing the vertical surfaces of the remaining

roots with sharp angles (Fig. 29-33).

Situation 1:

mandibular molar

Following separation, both roots are maintained. The

distal surface of the distal root and the mesial surface

of the mesial root must be prepared parallel with each

other to increase the retention for a subsequent resto

ration. The mesial surface of the distal root and the

distal surface of the mesial root should be prepared

TREATMENT OF FURCATION-INVOLVED TEETH • 721

Fig. 29-32. Radiographs of a mandibular first molar to be extracted and of a second molar to be root resected (a).

During hemisection an overhang is left behind as a result of an oblique sectioning of the tooth distal to the furcation (

b). In a radiograph obtained 2 years later, the presence of an angular bony defect can be seen adjacent to the "over-

hang" (c). The lesion was resolved and the angular defect disappeared following removal of the "overhang". Radio-

graph

after 2 years (d).

Fig. 29-33. Maintenance of the two fused buccal roots

of a maxillary first molar. The buccal roots were sepa-

rated from the palatal root. Note the rounded line an-

gles and the wide space created between the separated

roots.

Fig. 29-34. Mandibular molar after root separation.

Note the diverging angle of preparation performed to

increase the interradicular space between the mesial

and distal roots and the parallel approximal surfaces.

722 • CHAPTER 29

Fig. 29-35. The sequential stages of root resection and extraction of the distal root of a maxillary molar. In order to

minimize the concave outline of the cut surfaces, the sectioning should be performed with a straight line cut (a,b).

After extraction of the distal root, the furcation area of the remaining roots must be re-prepared to eliminate under

cuts (c, d).

Fig. 29-36. Preparation, during separation, of the mesiobuccal and palatal roots after the distobuccal root of a maxil

lary molar had been extracted. The internal (furcation) surfaces of the two roots should be prepared with diverging

angles to increase the interradicular space, while the external surfaces of the two roots should be prepared parallel

each other to increase the subsequent retention of the restoration (a,b). When the palatal surface of the palatal

root

is not prepared parallel to the buccal surface (c), the palatal abutment will become shortened and not self-reten

tive.

with diverging angles to increase the space available

between the separated roots (Fig. 29-34).

Situation

2: maxillary molar

Following separation, the distobuccal root was ex-

tracted. The distal surface of the crown is prepared

with

a bevel cut and in such a way that the concave

curvature (in apicocoronal direction) is eliminated

(Fig.

29-35a-d).

If the mesiobuccal and the palatal roots of this

molar

must be separated but maintained, it is important that

the buccal surface of the mesiobuccal root and

the

palatal surface of the palatal root are prepared

parallel

with each other. This will enhance the reten

tion of the

subsequent restoration. The palatal surface

of the

mesiobuccal root and the buccal surface of the

palatal

root must be prepared at diverging angles to increase

the space available between the separated

roots (Fig. 29-

36a-c).

The provisional restoration is at this stage relined

with cold cured acrylic and cemented after RSR.

Periodontal surgery

Following flap elevation, osseous resective techniques

are used to eliminate angular bone defects that may

exist around the maintained roots. Bone resection may

also be performed to reduce the buccolingual dimen-

sion of the alveolar process of the extraction site. The

remaining root(s) may be prepared with a bevel cut to

the level of the supporting bone (Levine 1972, Ram-

fjord

& Nissle 1974, Carnevale et al. 1983). This addi

tional

preparation may serve the purpose of (1) elimi

nating

residual soft and hard deposits and (2) eliminating

existing undercuts to facilitate the final impres

sion (Fig.

29-37a-f). The provisional restoration is re-

lined. The

margins of the provisional restoration must

end >_ 3

mm coronal of the bone crest. The soft tissue

flaps are

secured with sutures at the level of the bone

crest. The

relined provisional restoration is cemented

and a

periodontal dressing is applied to cover the

surgical

area. The dressing and the sutures are re-

moved 1 week

later. The roots are debrided and a new

dressing applied.

After another week, the dressing is

TREATMENT

FURCATION-INVOLVED TEETH • 723

Fig. 29-37. Sequential stages of root resection at maxillary first and second molars. The extraction of the distal root

of the first molar was performed during tooth preparation and prior to the insertion of the provisional restoration

(a,b). During the surgical procedure, after flap elevation, the furcation-involved second molar was separated,

the

mesial and palatal roots were extracted and the osseous defects were eliminated (c, d, e). Healing with the

defini

tive prosthetic restoration in place (f).

finally removed and the patient instructed in proper

plaque control techniques.

Final prosthetic restoration

Since the prosthetic preparation of the roots was com-

pleted during surgery, the clinician concerns him/her-

self with only minor adjustments. The preparation

margins are located supragingivally, which improves

the precision of the definitive crown restoration. The

framework of the restoration must be rigid to compen-

sate for the compromised abutments (roots) with a

compromised periodontal tissue support. The occlu-

sion should be designed to minimize the infliction of

lateral deflective forces (see Chapter 30) (Fig. 29-

38a,b).

Regeneration of furcation defects

The possibility of regenerating and closing a furcation

defect has been investigated (see Chapter 28).

Following an early case report publication

(Gottlow

et al. 1986), where histologic documentation

of new

attachment formation in human furcation de-

724 •

CHAPTER

Fig. 29-38. Soft tissue healing at a separated maxillary first molar and at a root-resected second molar (a). The final

prosthetic restoration in place with the occlusion designed to minimize the lateral stresses on the roots left as abut

ments (b).

Fig. 29-39. Histologic mesiodistal section of a previous

degree II furcation involvement of a human mandibu

lar molar, treated with GTR. The section demonstrates

that the newly formed cementum covers the entire cir

cumference of the furcation defect.

fects (Fig. 29-39) treated by "guided tissue regenera-

tion" (GTR) therapy was provided, the results of sev-

eral investigations on this form of treatment in furca-

tion-involved teeth have been presented. In these re-

ports, a reasonably predictable outcome of GTR ther-

apy was demonstrated only in degree II furcation-in-

volved mandibular molars, where a clinical soft tissue

closure or a decreased probing depth of the furcation

defect was recorded (Pontoriero et al. 1988, Lekovic et

al. 1989, Caffesse et al. 1990).

Less favorable results have been reported when

GTR therapy was used in other types of furcation

defects such as degree III furcation-involved mandib-

ular and maxillary molars (Pontoriero et al. 1989, Pon-

toriero & Lindhe 1995a) and degree II furcations in

maxillary molars (Metzeler et al. 1991, Pontoriero &

Lindhe 1995b).

The reason for the limited predictability of GTR

Fig. 29-40. Position of the furcation fornix in relation to

the level of the supporting bone and attachment appa

ratus in a lingual degree II furcation-involved

mandibular molar.

therapy in furcation-involved teeth may be related to

several factors:

•

The morphology of the periodontal defect, which in

the root complex often has the character of a "hori-

zontal lesion". New attachment formation is hence

dependent on coronal upgrowth of periodontal

ligament tissue (Fig. 29-40).

•

The anatomy of the furcation, with its complex

internal morphology, may prevent proper instru-

mentation and debridement of the exposed root

surface (Fig. 29-41).

•

The varying and changing location of the soft tissue

margins during the early phase of healing with a

possible recession of the flap margin and early ex-

posure of both the membrane material and the for-

nix of the furcation (Fig. 29-42).