ATREVIEVY OF ROOTARESECTIVETHERAPY,ASA

TREATMENT OPTION FOR MAXILLARY MOLARSTIMOTHY HEMPTON, D.D.S.; CATALDO LEONE, DM.D., D.SC.

Restorative treatment planningis often confounded when periodontalattachment loss, caries ortooth fracture involves the furcationarea of the tri-rooted maxillarymolars. Although such involvementinvariably diminishesthe long-term prognosis of theaffected teeth, extraction is notalways an option. Root resectivetherapy, which removes the involvedroot plus its associatedcrown portion (trisection), is oneof several treatment modalitiesthat can be used in such cases.This article reviews the indicationsand contraindications forroot resective therapy, describesthe technique of surgical trisectionand presents a case inwhich combined resective, endodonticand prosthetic managementresulted in a successfuloutcome.

) ne of the most compelling challenges we face in dentistry todayis treatment planning in the posterior maxilla. Multirooted teethsuch as maxillary molars have root contours that greatly limit accessibilityto cleaning during nonsurgical and surgical therapy.1'2The maxillary molar usually has three roots. These roots may be divergentor fused, or they can be divergent coronally and fused apically(Figure 1). The locations of separation of the roots from theroot trunk-the furcation areas-typically occur on the mesial, distaland buccal aspects of maxillary molars.Periodontal disease that extends into the furcation areas canpose significant difficulty during treatment, as can extensive cariesor root fractures that involve the furcation areas. Treating any of

these problems is particularly difficult with regard to the interproximalfurcation areas (mesial and distal), as the disease process andsubsequent treatment could affect the periodontal attachment apparatusof the adjacent teeth. Root resective therapy can be usedwhen attachment loss, caries or a fracture involves a furcation areaof a maxillary molar.This article reviews root resective therapy and the concomitantendodontic and prosthetic management as a treatment option formaxillary molars. The indications and techniques of this treatmentare presented as well as literature that reports success and failureof this treatment.REVIEW OF RELEVANT LITERATURE

A significant number of papers have been published regarding thepotential for success with root resective therapy.34 Endodontic therapyis typically performed either before or after root resection.Endodontic complications (root fractures) have been cited as a reasonfor eventual failure of teeth treated with root resectivetherapy.57 A root from a maxillary molar and the associated portionof the crown supported by that root can be removed, rather thanamputating just the root as it emanates apically from the crown.Greenstein called this treatment of maxillary molars a trisection ofthe tooth.8 Keough reviewed the technique of removing a root andits accompanying crown portion while concurrently modifying theemergence profile of the tooth as it emanates from the osseouscrest. He advocated recontouring adjacent osseous structures to reestablish

positive osseous architecture.9JADA, Vol. 128, April 1997 449Downloaded from jada.ada.org on September 25, 2010

~~C[INICAL PHACTIIELAL iLf13 L~Figure 1. Maxillary molars can have divergent roots (A), fused roots (B)or roots that diverge coronally and fuse at the apex (C).

Modifying tooth structure inthis fashion eliminates undercutsand has been described asa "barreling in" of the rootform.'0 Crown preparation ofthe altered tooth and prostheticcontours to allow increased accessby the patient has beendemonstrated by Kastenbaum."1Carnevale and others"2 reporteda success rate of 95 percent forroot resective therapy using thesurgical and prosthetic proceduressimilar to those advocatedby Keough9 and Kastenbaum".Proper selection of teeth, conservativeendodontic access andthe design of the prosthetictreatment may have lead to thelow failure rate.Determining whether themorphology of the tooth isamenable to root resective therapyis critical. An important factoris the length of the roottrunk. This length can be definedas the distance betweenthe cementoenamel junction andthe opening of the furcation. Atooth with a long root trunk isless likely to have furcation involvement,as the junctional epitheliummust traverse a longer

distance before the roots separate.Wrhen furcation involvementoccurs on this tooth, however,successful resectivetherapy is not as predictable becausethe length of the remainingroots may not be longenough for support. In addition,removing one root followed byosseous resection to establishpositive osseous contours wouldinvolve excessive osseous removalon the adjacent teeth.Teeth with short root trunksare more likely to have furcationinvolvement as the j'unctionalepithelium migrates apically.With less distance for thejunctional epithelium to traverse,furcation involvement ismore likely. But when theseteeth are treated with root resection,the prognosis is greatlyimproved. Radiographs can helpdetermine the root trunk morphology.'13Majzoub and Kon'14 describedtooth morphology after distobuccalroot resection in maxillaryfirst molars. Root removalwas accomplished by using thetechnique described by Keough.The root was sectioned throughthe coronal aspect of the tooth.The distobuccal root and its accompanyingcrown portion wereremoved simultaneously, resultingin an elimination of all undercuts(a trisection procedure).Figure 2 shows a maxillary first

molar after a trisection procedure.One of the parametersthat the authors looked at wasthe distance between the distalaspect of the pulp chamber floorand the most coronal aspect ofthe root separation. They determinedthat the average valuefor this distance was 2.7 millimeters.But only 6 percent ofthe teeth consistently had a distanceof 3 to 4 mm.'"It is necessary to consider theadvantage of surgical accessand trisection through thecrown, which provides propervisualization of the location ofthe floor of the pulp chamber,and the most coronal aspect ofroot separation. This informationenables the practitioner todetermine the feasibility of retainingthe remaining portion ofthe tooth and providing a castrestoration.Backman"1 described fourcases in which incomplete rootresections w'ere performed.Continued osseous loss was observedafter root amputation.The author commented that theinitial surgical access may havebeen inadequate. In addition,he recommended a postoperativeradiograph to determinethe accuracy of root removal."Newell'16 examined 70 root-resectedteeth and describedfaulty root resections in 30 percentof the teeth examined.Practitioners using the root amputation

technique had left subgingival,residual roots, furcaltips and/or ledges (Figure 3)."450 JADA, Vol. 128, April 1997Downloaded from jada.ada.org on September 25, 2010

CLINICAL PRACTICEFigure 2. In a maxillary first molar, throot was removed via a trisection aniquently prepared for full coverage. Ddistance between the floor of the pulthe fomix of the furcation. A measurefor D would allow for 1 mm of margintooth structure and 2 mm for the suptachment apparatus (biologic width).

These subgingival structuresencourage future periodontaldisease because they are potentiallyplaque-retentive. Currentthinking is that a confluence ofthe root to prosthetic crown contoursis more beneficial; axialcontours of restored teeth mustbe physiologically developedand emerge from the root with azero-degree emergence profile.Flat contours that follow theroot morphology are lessplaque-retentive than the contoursof restored teeth with acervical bulge at the apical portionof the crown.'1720INDICATIONS ANDCONTRAINDICATIONS FORROOT RESECTIVE THERAPY

Indications. Rosenberg andcolleagues" listed the followingindications for root resection:- a severe osseous defectaround one root with adequateosseous supporton the adjacentroots (the osseousdefect canbe a one-, twoorthree-walledinfrabony lesion);

- grade II orIII horizontalfurcation involvementwitha negligible verticalcomponentof osseous losson the roots tobe retained;- adverse rootproximity to anadjacent tooth;e distobuccal - severe cariesd was subserepresentsthe that extendslp chamber and into the rootement of 3 mmplacement on and/or the furracrestalat- cation area;- an endodonticperforationsuch as perforation of the pulpchamber floor or a lateral perforationof a root canal;- a root fracture that involvesonly one root.Contraindications. In ourexperience, root resective therapyshould not be considered inthese situations:- used roots;- unfavorable root anatomy forthe remaining roots (in general,maxillary molars with shortroot trunks and more divergentroots have a more favorableprognosis when root resectivetherapy is used; teeth with longroot trunks and roots in closeproximity are poor candidatesfor root resective therapy);- excessive mobility that didnot improve after initial therapy(that is, nonsurgical therapywith possible concomitant

chemotherapeutic agents);- inadequate osseous supporton the remaining roots leadingto a poor crown-to-root ratio;- the teeth mesial and distal tothe affected tooth have largerestorations that warrant castrestorations; retaining the involvedmolar may not be necessaryif a three-unit fixed bridgecan be fabricated.TECHNIQUE FOR ROOTRESECTION OF MAXILLARYMOLARS

Root removal. There are twoways to remove the affectedroot: with or without the associatedcrown portion. Removal ofa root only, without its accompanyingportion of the crown, isreferred to as a root amputation."This can be done with along fissure bur or diamond,with copious irrigation, and byamputating the root at the CEJ.This leaves the crown portionintact except for the apertureassociated with the entrance ofthe root canal of the involvedroot into the pulp chamber. Thisarea can be widened, and arestorative material such asamalgam can be placed. The reflectionof a gingival flap oftenenhances access in root amputationprocedures."Trisection" is the term appliedspecifically to surgical excisionof a maxillary molar rootand its accompanying crownportion; the same procedure iscalled a "hemisection" when performedon a mandibularmolar.23'24 Similar to the root amputationprocedure, elevation of

buccal and palatal mucoperiostealflaps enhances access tothe involved teeth as well as tothe adjacent osseous structures.A long fissure bur on a highspeedhandpiece is placed alongthe long axis of the tooth in thearea of the buccal furcation anda cut is made. This cut is chan-JADA, Vol. 128, April 1997 451Wvw ! :!y WW W :: W! W!

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CLINICAL P RACIICEFigure 3. After a faulty root resection,a subgingival residualfurcal tip is present on this maxillarymolar.

neled toward the center of thetooth and then directed towardthe interproximal furcationopening of the affected root. Thecuts are made essentially overthe portion of the crown that issupported by the root to be removed.When viewed occlusally,a C-shape typically appears asthe cut is made.The bur is moved from theinterproximal opening towardthe buccal area in a back-andforthmotion, and concurrentlymoved apically toward the furcationarea. Once the bur seversthe floor of the pulp chamber,the root is separated from theremaining portion of the tooth.The bur must not be extendedapically to the floor of the pulpchamber to resect the underlyingosseous structures. Thesestructures are recontoured asneeded after the root is removedand direct visualization is possible.The severed portion of theroot can be removed with a periosteal

elevator and/or a smallextraction forceps. The remainingportion of the root is barreledin to remove any ledges orundercuts, as these structuresare potentially detrimental toperiodontal maintenance.Osseous recontouring.When odontoplasty is completed,osseous therapy can begin.The practitioner should establishadequate soft tissue widthbetween the restorative marginand the osseous crest and createpositive osseous architecture onthe tooth undergoing root resectionand on the adjacent teeth.Positive osseous architecturecan be described as the topographicarrangement of hardtissues where the crest of theinterdental tissue (interproximalbone) is coronal to the levelof the radicular osseous tissue,facially or lingually.High-speed rotary instrumentationwith copious amounts ofwater can eliminate any osseousdefects while establishing moderateparabolic contours on theproximal surfaces and flat contoursin the interproximal areas.When this has been completed,the osseous crest on the proximalsurfaces will be apical tothe osseous crest in the interproximalareas. There will be aminimum of 3 mm from the floorof the pulp chamber to the osseouscrest. Two of those millimetersallow for establishmentof the supracrestal attachmentapparatus, the so-called biologicalwidth, and 1 mm for placement

of the crown margin. If theremaining root trunk-the distancefrom the floor of the pulpchamber to the fornix of the furcation-is wide enough, additionaltooth structure will be obtainedthrough osseousresection to allow for more distancebetween the junctionalepithelial attachment and thecrown margin. A minimum of atleast 0.5 mm is desirable.Clearly, reflection of flapsand surgical access provide notonly for proper osseous recontouringand odontoplasty butalso visualization of the distancebetween the floor of thepulp chamber and the separationof the two remaining roots.This also allows the dentist toeliminate undercuts.Repositioning of gingivalflaps. The aforementioned measurementsare of great concernif prosthetic treatment is to bedone using the concept of the biologicalwidth.25 If this conceptis used, a minimum distance ofabout 2 mm is needed betweenthe osseous crest and the proposedrestorative margin. Onemillimeter would account forthe supracrestal fibrous insertioninto the cementum and thesecond millimeter would accountfor attachment of thejunctional epithelium accordingto the average measurementsreported by Gargiulo and colleagues.26 Even though these averagemeasurements mightallow establishment of thesupracrestal attachment apparatus,

the restorative marginwould still be in close proximityto the junctional epithelial attachment.In theory, however,this attachment would not beviolated. Certainly, an increasedtooth structure wouldbe beneficial so the restorativemargin could be placed coronallyto the base of the sulcus-themost coronal aspect of the junctionalepithelium.No definitive scientific study,however, has documented theneed to establish these dimensionsfor periodontal health.Dello Russo, in a letter to theeditor of The Journal ofPeriodontology,27 pointed out452 JADA, Vol. 128, April 1997Downloaded from jada.ada.org on September 25, 2010

CLINICAL PRACTICEFigure 4. Tooth no. 14 has a fracture on the mesialaspect that extended into the furcation area. Teethnos. 3 and 15 had no restorations.Figure 5. Surgical exposure of tooth no. 14. Themesiobuccal root has been removed and positiveosseous contours established.

that the range of values for theepithelial attachment was 0.08to 3.72 mm, and the range forthe connective tissue attachmentwas 0.00 to 6.52 mm inGargiulo and colleagues' 1961paper. Dello Russo27 questionedthe extrapolations made fromthat article which are utilizedas guidelines for performingcrown lengthening procedures.If the epithelial attachment andthe connective tissue attachmentmeasurements could be aslow as 0.08 mm and 0.00 mmrespectively, then it is possiblethat "an individual patient

might have a perfectly healthyperiodontium with very little biologicwidth."CASE REPORT

Figure 4 shows a case in whichtreatment planning could involvefixed prostheses over naturalteeth, implant placementor root resective therapy. Thepatient, 44 years old and ingood health, had a fracture onthe mesial aspect of tooth no. 14.This fracture extended into thefurcation area, separating themesiobuccal root from the remainingportion of the tooth.Using fixed prostheses wouldhave meant extracting tooth no.14, followed by fabrication of athree-unit fixed bridge. The potentialdistal and mesial abutments,teeth nos. 13 and 15,were unrestored, caries-freeteeth. The radiograph indicatedthat the mesiobuccal andpalatal roots were divergentand of adequate length to allowfor a reasonable crown-to-rootratio after resection of themesiobuccal root.Root resection was deemedmore favorable because of theobserved positive morphologicalcharacteristics of the affectedtooth weighed against thepreparation of the adjacentteeth or placement of an implantinto bone of potentiallypoor quality. Figure 5 is a surgicalview of the maxillary molarshown in Figure 4 (preoperativeview). The mesiobuccal root hasbeen removed and osseous recontouringperformed, establishing

positive osseous architectureand an adequatedistance between the floor ofthe pulp chamber and the crestof bone. Odontoplasty has eliminatedall undercuts. Aftersurgery, the buccal and palatalflaps were sutured at the osseouscrest.When osseous resective therapyis used and after healing iscomplete, the gingival contoursreflect the underlying surgicallycreated osseous contours. Thecoronal development (the extentof height) of the interproximalgingival tissue on the mesial aspectof the maxillary molar wasreduced because of the alterationof the emergence profile ofthe mesial aspect of the tooth.After surgery and an adequatetime for proper healing (abouteight weeks), we initiated finaltooth preparation (Figure 6).The outline of the root was followedand the undercuts initiatedduring surgery were removedin the final preparation.Root resection and final preparationremoved the mesiobuccalportion of the tooth, resulting inan L-shape, or pork-chop type ofappearance, when the crownpreparation is viewed from theocclusal aspect. The concavityon the mesial portion of thetooth represents that part of thecrown that was supported bythe resected mesiobuccal root.When prepared in this fashion,the outline of the preparedtooth represents the outline ofthe resected tooth at the level of

the epithelial attachment.We recommend a light cham-JADA, Vol. 128, April 1997 453Downloaded from jada.ada.org on September 25, 2010

-CLINICAL PRACTICEFigure

6. Final preparation of tooth no. 14 (Figures4, 5) for a full-coverage cast restoration. The crownpreparation follows the contours of the remainingroot structure as it emanates from the periodontium.

fer for the finish line for thispreparation. This is particularlyimportant in the area of the resection.At this location, a satisfactoryamount of availabletooth structure for a shoulderpreparation is not always available.In addition, the tooth hasnow been lengthened, whichcauses a similar problem aroundthe rest of the tooth outline. Thislight chamfer can be representedin the final cast restoration by 2to 3 mm of metal (a metal collar).This allows us to place the porcelainat a more coronal portionwhere more support on the metalunderstructure is available.Usually, aesthetics are not amajor concern in the area of themaxillary molars. Another optionis an all-gold crown. The finalrestoration is also barreled in atthe area of the root resection.The crown emerges from thegingiva for the first 2 mm at azero-emergence profile. This eliminatesthe plaque-retentive contoursof a crown that bulges directlyinto the gingival tissues as itemanates from the crown margin.The contours of this crown resultin large embrasure areas;however, these areas can becleaned easily. End-tufted

brushes or proxy-brushes can beFigure 7. A cast restoration has been placed on toothno. 14. A large gingival embrasure area is evident onthe mesial aspect of this tooth because a cervicalbulge has not been created to replace the portion ofthe crown that would have emanated directly fromthe mesiobuccal root. The crown emerges from the

used for main- periodontium with a zero-degree emergence profile,tenance. Figure following the morphology of the root structure as itemanates from the soft tissue.

7 shows apalatal view ofthe final crown placed on themaxillary first molar, which wastreated with a root resection.The first 2 to 3 mm of the crownare metal. A large embrasurearea is present between teethnos. 13 and 14. This embrasurearea represents the emergenceprofile of the tooth, which graduallyextends mesially to form acontact with the premolar. Thisrestoration has functioned forabout four years.DISCUSSION

Because two of the three furcationareas associated with maxillarymolars are located in interproximalareas, clinicians should recognizethat these interproximalareas can be particularly susceptibleto plaque-induced inflammation.One reason for this increasedrisk is that patients maybe less inclined to use dentalfloss, a highly effective techniquefor maintenance of this area. Inaddition, the gingival col apicalto the contact areas has histologiccharacteristics that allow easierpenetration of plaquecomponents.28The subsequent inflammatoryresponse may initiate osseousloss, which can result in an infrabony

defect. The extent of thedefect may be influenced by thebuccolingual dimensions of thealveolar bone, the vascularity ofthe osseous tissue and the morphologyof the adjacent roots.This last parameter also has significantimpact on the treatmentsuccess. Concavities of adjacentroots can reduce or limit accessfor adequate detoxification.Once furcation involvementoccurs on the mesial or distalaspects of a maxillary molar,our concern focuses not only onthe involved tooth but also onthe potential for periodontal deteriorationon the proximal premolaror molar. Treatment optionsfor furcation involvementinclude: scaling and root planing,tetracycline-impregnatedfibers, open-flap clean-out, guidedtissue regeneration or resectivetherapy. The first four optionsare limited by the extent of thefurcation involvement, the contoursof the involved roots andthe morphology of the osseous de-454 JADA, Vol. 128, April 1997Downloaded from jada.ada.org on September 25, 2010

CLINICAL PRACTICEfect. Guided-tissue regenerationhas proved more predictable inthe treatment of furcation areasassociated with mandibular molarsthan with maxillary molars.25Interproximal access may be acritical factor.Resective therapy providesimproved access during bothsurgery and postoperative

maintenance. Resective therapyincludes osseous recontouring,odontoplasty, root resection andextraction. Extraction is, ofcourse, the ultimate resectivetherapy. Extracted maxillarymolars can be replaced withconventional fixed bridges orimplants. If the proposed abutmentsare unrestored, cariesfreeteeth, we may use implanttherapy. One variable to consideris the osseous quality of theposterior maxilla. Significantimplant failure has been notedas the ratio of cancellous to corticalbone increases.30 Root resectionand subsequent endodonticand prostheticmanagement, if carefully chosen,may be a more viable optionthan implant therapy orfixed prostheses utilizing unrestored,caries-free teeth as abutments.Recognizing that thistreatment has a place in conventionaldental therapy hasbeen the aim of this paper.SUMMAVflRYExtensive periodontal, endodonticor caries involvement ofmaxillary molars makes thetreatment decision-making processdifficult because the resultingfurcation exposures are difficultto manage. The techniqueof trisection described here illustratesone way to facilitatetreatment planning of maxillarymolars that have exposed furcationareas. This technique isparticularly useful when the involvedtooth has divergentroots, a short root trunk and an

adequate distance between theseparation point of the remainingroots (fornix) and the floor ofthe pulp chamber. Conversely,this therapy is of little value inteeth with fused roots, long roottrunks or unfavorable anatomyof the remaining roots. Propercase selection enhances therapeuticsuccess. o