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2010;141;647-655 J Am Dent Assoc Timothy J. Hempton and John T. Dominici A Review Contemporary Crown-Lengthening Therapy: jada.ada.org ( this information is current as of June 20, 2010 ): The following resources related to this article are available online at http://jada.ada.org/cgi/content/full/141/6/647 in the online version of this article at: including high-resolution figures, can be found Updated information and services http://jada.ada.org/cgi/collection/esthetics Esthetics http://jada.ada.org/cgi/collection/periodontics Periodontics : subject collections This article appears in the following http://www.ada.org/prof/resources/pubs/jada/permissions.asp this article in whole or in part can be found at: of this article or about permission to reproduce reprints Information about obtaining © 2010 American Dental Association. The sponsor and its products are not endorsed by the ADA. on June 20, 2010 jada.ada.org Downloaded from

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  • 2010;141;647-655 J Am Dent Assoc

    Timothy J. Hempton and John T. Dominici A Review

    Contemporary Crown-Lengthening Therapy:

    jada.ada.org ( this information is current as of June 20, 2010 ):The following resources related to this article are available online at

    http://jada.ada.org/cgi/content/full/141/6/647in the online version of this article at:

    including high-resolution figures, can be foundUpdated information and services

    http://jada.ada.org/cgi/collection/estheticsEsthetics http://jada.ada.org/cgi/collection/periodonticsPeriodontics

    : subject collectionsThis article appears in the following

    http://www.ada.org/prof/resources/pubs/jada/permissions.aspthis article in whole or in part can be found at:

    of this article or about permission to reproducereprintsInformation about obtaining

    © 2010 American Dental Association. The sponsor and its products are not endorsed by the ADA.

    on June 20, 2010 jada.ada.org

    Dow

    nloaded from

    http://jada.ada.org/cgi/content/full/141/6/647http://www.ada.org/prof/resources/pubs/jada/permissions.asphttp://jada.ada.org

  • C O V E R S T O R Y

    JADA, Vol. 141 http://jada.ada.org June 2010 647

    In contemporary dentistry, dentists areconfronted on a daily basis with clinicaldecision making regarding dentitionaffected with significant caries or sub-gingival fractures. The dentist weighs

    the clinical findings and patients’ concerns inthe balance to determine if the tooth or teethshould be extracted or restored. We are, ofcourse, in an age of dental implants, an era inwhich heroic efforts to salvage extensively

    damaged teeth arewaning. This, how-ever, does not meanthat dentists shouldabandon tools com-monly used to pre-serve the naturaldentition, tools suchas complex restora-tive treatment, pos-

    sible concomitant endodontic therapy andperiodontal therapy. Moreover, if the patientwishes to retain part or all of his or her owndentition, providing the outcomes of thesetreatment options are predictable, the dentistshould consider honoring those wishes.

    When caries or fractures are extensiveand subgingival, a dentist may opt to usecrown-lengthening therapy to expose solidtooth structure and thus to facilitaterestorative therapy. Our purpose in thisarticle is to review the goals, basic surgicalprinciples and wound healing associatedwith crown-lengthening surgery. In addi-tion, we discuss potential positive and nega-tive outcomes of this therapy. In addition,we present a report of a clinical case fol-lowed for eight years to illustrate the con-cepts outlined in this review.

    We used PubMed and Google Scholarsearch engines to identify pertinent litera-ture regarding crown lengthening and res-

    Dr. Hempton is an associate clinical professor, School of Dental Medicine, Tufts University,Boston. He also maintains a private practice in periodontics and implantology in Dedham,Mass. Address reprint requests to Dr. Hempton at 347 Washington St., Suite 103, Dedham,Mass. 02026, e-mail “[email protected]”. Dr. Dominici is a staff endodontist and faculty member, General Practice Residency andProsthodontic Residency Programs, Michael E. DeBakey Veterans Administration MedicalCenter, Houston.

    Contemporary crown-lengthening therapyA review

    Timothy J. Hempton, DDS; John T. Dominici, DDS, MS

    Background. The authors conducted a literature reviewregarding the rationale, basic surgical principles, contraindica-tions and wound healing associated with periodontal crown-lengthening surgery. They present a report of a clinical caseillustrating crown lengthening with osseous resection.Types of Studies Reviewed. The authors evaluatedclinical and radiographic studies, as well as literaturereviews. They selected only publications that pertained to thesurgical exposure of the natural dentition to facilitate restora-tive therapy, esthetic concerns or both. Results. Periodontal crown lengthening can be used foresthetic enhancement in the presence of delayed passive erup-tion. Moreover, for teeth with subgingival caries, fractures orboth, this treatment can establish a biological width and, ifneeded, a ferrule length facilitating prosthetic management.Crown-lengthening surgery involves various techniques,including gingivectomy or gingivoplasty or apically positionedflaps, which may include osseous resection. Authors of wound-healing investigations have reported that an average of 3 mil-limeters of supragingival soft tissue will rebound coronal tothe alveolar crest and can take a minimum of three months tocomplete vertical growth. Clinical Implications. Initiation of final prosthetic treat-ment should wait at least three months and possibly up to sixmonths for esthetically important areas, as the free gingivalmargin requires a minimum of three months to establish itsfinal vertical position. Dentists must be aware that osseousresection could affect periodontal stability and may pose acontraindication to crown-lengthening therapy.Key Words. Crown lengthening; gingivoplasty.JADA 2010;141(6):647-655.

    A B S T R A C T

    This article is a preview of apresentation that will begiven at the American DentalAssociation’s 151st AnnualSession and World Market-place Exhibition. The annualsession information begin-ning on page 721 providescomplete details on the program.

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    toration by using the key words “ferrule,” “posts,”“endodontic dowel core,” “post retention,” “rootfracture,” “endodontics,” “core restoration,” “postdesigns,” “fracture resistance” and “post-core.”

    RATIONALE FOR CROWN-LENGTHENINGSURGERY

    Esthetic and functional concerns. The indica-tions for crown-lengthening surgery includeesthetic enhancement, exposure of subgingivalcaries, exposure of a fracture or some combinationof these. Crown-lengthening surgery has beencategorized as esthetic or functional. The term“functional” relates to exposure of subgingivalcaries, exposure of a fracture or both. Often, thediscussion of crown lengthening in the anteriorsextants is presented in the context of estheticsurgery. Excess gingival display can occur whenpassive eruption has been delayed. The result isthe appearance of short clinical crowns. In thepresence of a medium or a high lip line, this con-dition is more noticeable. If the patient desires ananterior dentition that is more normal in toothlength, resective treatment that exposes theanatomical crowns may be warranted.1,2

    Indeed, functional and esthetic therapy canconverge in the esthetic zone when subgingivalcaries does not extend greatly or at all to the root.In these cases, the dentist may need a surgicalstent as a guide to determine the position of thenew crown margins. If the interdental tissueneeds to be removed during surgery, the potentialfor an esthetic compromise can be reduced oreliminated via compensating prosthetic crowncontours. The dentist can conceal or correctwidened embrasure areas that may result afterhealing from the surgical procedure by length-ening and widening the crown contact areas toaccommodate the new morphology of the inter-proximal papillae.

    A caveat that the dentist must address forcrown lengthening in areas of the dentition visibleduring smiling is the potential for an esthetic com-promise relative to the gingival framework. In anesthetically important area in which the free gin-gival margin may be located significantly coronalto the cementoenamel junctions (CEJs) of the den-tition, resection of these excess tissues may notpose a high risk of developing a problematic situa-tion. This is true, even if full-coverage restorationsare not planned, as long as the interdental tissuesare not involved in the process of resection.3 Resec-tive therapy, however, may result in facial root

    exposure if the free gingival margin alreadyapproximates the CEJs of the dentition in anesthetic area. Moreover, an altered morphology ofthe anterior dentition’s interdental papillae afterhealing also is a concern. Black triangles maydevelop if the postresection distance between thecontact area and the interdental osseous crest isgreater than 5 millimeters.4

    The biological width. In addition to exposingsupragingival tooth structure for restorativetherapy, dentists excise tissues so that crownmargins do not impinge on the so-called biologicalwidth. A review of the literature reveals differingopinions regarding the occlusoapical length of thebiological width. Gargiulo and colleagues5 de -scribed the dimensions of the dentogingival junc-tion. They reported the average length of the den-togingival junction to be 2.04 mm. They identifiedthe subcomponents of the dentogingival junctionas the connective-tissue attachment (mean value:1.07 mm) and the epithelial attachment (meanvalue: 0.97 mm). Vacek and colleagues6 alsoinvestigated the dimensions of the dentogingivaljunction in human cadaver specimens. Theyreported mean values of 0.77 mm for the connec-tive-tissue attachment and 1.14 mm for theepithelial attachment. Ingber and colleagues7 sug-gested that the term “biologic width” relates tothe average value of the dentogingival junction—that is, approximately 2 mm. They suggested thatan additional 1 mm be added coronal to the 2 mmdentogingival junction as an optimal distancebetween the bone crest and a restorative margin.The authors reasoned that “adding the 1 mm tothe average 2 mm of the biologic width estab-lishes a minimum dimension of 3 mm coronal tothe alveolar crest that is necessary to permithealing and proper restoration of the tooth.”7

    Nevins and Skurow8 also described the impor-tance of a 3-mm biological dimension separatingthe osseous crest by a safe distance from theplaque associated with crown margins.

    In contemporary practice, it generally isaccepted that a 3-mm distance would significantlyreduce the risk of periodontal attachment lossinduced by subgingival restorative margins.Placing the restoration in close proximity to theosseous crest has been demonstrated in a humanclinical study to induce chronic inflammation.9

    ABBREVIATION KEY. CEJs: Cementoenamel junctions.

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    Moreover, results from an animalinvestigation involving histologic evalu-ation indicated that restorative mar-gins impinging on the osseous crestmay result in bone resorption.10

    Ferrule length. A ferrule is a metalring or cap intended for strengthening.The Journal of Prosthetic Dentistry’s2005 Glossary of Prosthodontic Termsdefines a ferrule as a metal band orring used to fit the root or crown of atooth.11 Sorensen and Engelman12 rede-fined the ferrule effect as “a 360-degreemetal collar of the crown surroundingthe parallel walls of the dentineextending coronal to the shoulder of thepreparation.” Figure 1 illustrates a pre-pared and restored tooth with a ferruleand a prepared and restored toothwithout a ferrule.

    For better understanding of the con-cept of the ferrule, we should examine thedynamics related to full-coverage restorationsused as a restorative option when tooth structurehas sustained severe damage. Often, the dentistreplaces the lost tooth structure with a founda-tion restoration before making the final prepara-tion for a full-coverage restoration. Furthermore,if the breakdown in tooth structure has impingedon the pulp or if little residual supragingivaltooth structure remains, endodontic therapy andconcomitant placement of a post and core may benecessary to allow intracanal retention of the res-toration. The placement of the foundation restora-tion results in an increase in clinical crownheight, width or both, thereby increasing theretention of the full-crown restoration. Underthese circumstances, however, supragingivalcrown preparation may result in a margin that ispartially or entirely seated on foundation restora-tive material.

    A basic prosthetic concept is that the greatestamount of retention and resistance to dislodge-ment of the restoration occurs at the apical one-third of the preparation. It is in this location thatparallelism is most critical. In this situation, afterplacement of a full-coverage restoration, theforces of occlusion generally may be transmittedto the foundation restoration.

    When a post-and-core restoration is placed toretain the core foundation, the occlusal forces maybe transmitted to the interface between theinternal aspect of the root and the post. The den-

    tist fills this area with cement to facilitate reten-tion of the post. The physical properties of thecement become critical. Fatigue of the cementunder occlusal stress could result in dislodgementof the post and core or, worse, fracture of the tooth.

    The advantage of exposing additional toothstructure in this clinical scenario is that the toothpreparation can extend in a more apical directionfor 1 to 2 mm. This additional surgically exposedtooth structure is provided in addition to exposureof the biological width so that the crown does notinvade the attachment apparatus; thereby, amore predictable prosthetic outcome isfacilitated.13

    This added disclosure of tooth structure cancontribute to the formation of a ferrule. In otherwords, the restorative margin is circumferentially1 to 2 mm apical to the most apical extent of thefoundation restoration or core buildup. This fer-rule height—the length of solid tooth structureengaged by the full-coverage restoration—maypermit the forces of occlusion to be dispersed ontothe periodontal ligament rather than concen-trating stresses at the post and core intraradicu-larly, which can increase the likelihood of failureof the tooth or the restoration. Libman andNicholls14 recommended a ferrule of at least 1.5 mm. Some investigators have reported that aferrule is not necessary.15,16 They argued that thelength of the post and the type of cement usednegate the concern about obtaining a ferrule.Morgano and Brackett17 advised that the pros-

    Ferrule No Ferrule

    Figure 1. A. A tooth prepared for a full-coverage crown with a ferrule. B. A tooth prepared for a full-coverage crown without a ferrule.

    A B

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    thetic principle of establishing a ferrule shouldnot be abandoned.

    As a result of the concern regarding obtaining a ferrule, lengthening the crown of a tooth withminimal supragingival tooth structure mayinvolve additional surgical removal of tissue. Inother words, the dentist may be required to exciseboth hard and soft tissue to facilitate developmentof a biological width of 3 mm, as well as a ferrulelength of 1.5 mm.

    Attempting to obtain a ferrule with additionalresection is not without its problems. Gegauff18

    pointed out that an attempt to gain an adequateferrule via a crown-lengthening procedure mayresult in compromise of tooth and biomechanicalleverage. He noted that the more apical relocationof the crown margin after crown-lengthening pro-cedures resulted in a preparationwith a thinner cross section. Thisreduction combined with the alteredcrown to root ratio could result in aweakened tooth. Orthodontic extru-sion may be another option toexpose tooth structure in some clin-ical situations. Any method used toincrease the ferrule length willreduce the root length invested inbone and possibly make the crown toroot ratio unfavorable. Furthermore, surgical andorthodontic procedures add to the cost of restoringthe tooth and prolong treatment.

    Most research investigating the ferrule hastaken the form of in vitro studies of single-rootedteeth. The influence of the ferrule effect on multi-rooted teeth is an area for further research. Also,without supporting clinical research or prospec-tive data, the clinician must question whetherappropriate restorative treatment still can be per-formed when a ferrule is absent or shorter thanthat advocated in the in vitro studies.

    BASIC SURGICAL CROWN-LENGTHENINGPROCEDURES

    Soft tissue. To plan a crown-lengthening pro-cedure, a dentist must think in three dimensions.In addition, he or she should be concerned aboutthe quantity and quality of residual gingival tis-sues left behind after the resected tissue hashealed completely.

    As a result, the first concern in flap design orexcision is the height of gingiva present on thefacial and lingual aspects of the involved tooth or

    teeth. The dentist can accomplish a tissue exci-sion via a gingivectomy by means of a scalpel, anelectrosurge, a radiosurge or a laser. Lasers havemade their way into conventional dental therapyfor use in performing gingivectomy or gingivo-plasty.19 Laser tissue ablation can result inadequate exposure of tooth structure with min-imal or no bleeding. This type of tissue removalcan result in a dry field, thus allowing the clini-cian to place a restoration immediately.

    The clinician, however, should not ignore theconcern regarding the width of gingiva in anocclusal apical height. Maynard and Wilson20 rec-ommended a minimum of 3 mm of attached gin-giva in the presence of subgingival restorativetherapy. A gingivectomy, no matter what tool thedentist uses to accomplish the excision, could

    result in complete removal ofattached gingival tissue.

    If soft-tissue excision via a gin-givectomy would result in a postop-erative gingival width of less than 3 mm, one should consider the api-cally positioned flap as an alterna-tive to a simple gingivectomy.21,22 Ifthe pretreatment level of gingiva isminimal, the dentist could make asulcular incision and position the

    flap apically to the osseous crest.23 This not onlywould preserve the amount of gingiva but alsowould increase the width of the attached gingivaafter healing.

    Another parameter to consider is the need tovisualize the bone. If the underlying bone crest isless than 3 mm from the level of gingival resec-tion, then the dentist should consider using anelevated flap procedure for access. A simple exci-sion of tissue probably would result in regrowth ofsoft tissue if the osseous crest is less than 3 mmapical to the existing free gingival margin. Inaddition, access to the bone yields the opportunityto perform additional resection of bone if the den-tist also intends to expose a ferrule.

    Osseous management. Regarding estheticimplant dentistry, Garber and colleagues24 stated,“The tissue is the issue, but the bone sets thetone.” In fact, this concept also is true for out-comes of periodontal surgery. The key to successis a three-dimensional analysis of the clinicalobjectives associated with the osseous componentof the proposed crown-lengthening surgery. Thefirst dimension is the occlusoapical dimension,

    Lengthening thecrown of a tooth

    with minimalsupragingival tooth

    structure may involveadditional surgicalremoval of tissue.

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    the second is the mesiodistal dimension and thethird is the buccolingual dimension.

    Two terms that describe osseous resection are“ostectomy” and “osteoplasty.” “Ostectomy” refersto removal of supporting bone; “osteoplasty”refers to removal of nonsupporting bone.Regarding tools used for bone resection, a dentistcan use hand chisels, high-speed rotary instru-mentation or a piezoelectric cutting device. Nomatter what tool the dentist uses, he or sheshould ensure that the treated bone is moistenedconstantly during the procedure to prevent desic-cation and associated postoperative pain anddelayed healing.

    When resective osseous surgery is performed toeliminate osseous deformities or reshape healthybone for exposure of tooth structure, the final con-tours of the underlying osseousstructure influence the overlying gin-gival tissues.25 When the bone haspositive architecture after therapy,wound healing results in scallopedgingival architecture with minimalsulcus depth. The achieved reductionin probing depths can be maintainedin the long term for nonsmokers andformer smokers who practice properoral hygiene and compliance with aprofessional maintenance program.26

    If reverse architecture remains after a toothwith a surrounding healthy periodontium hasundergone crown lengthening, excess gingivaltissue may rebound in the healing phase. Thisrebound would result in inadequate exposure ofthe treated dentition. If periodontal disease andassociated intrabony defects are present in con-junction with the need to lengthen a tooth’scrown, the dentist should eliminate those defor-mities and establish positive architecture. Failureto eliminate osseous deformities poses a risk ofpockets’ being present after surgery.27,28

    The extent of bone resection. In decidingwhich and how much bone should be removed, thedentist’s first concern is determining whether thelesion associated with the tooth requires Class V,Class II or full-coverage restorative treatment. Ifthe lesion is located solely on the facial aspect,then the dentist can perform the needed osseousremoval solely on the facial or lingual aspect.Moreover, the resection would be limited toaltering the bone in the occlusoapical dimension,thereby attaining a 3-mm dimension of supra -crestal tooth exposure (distance for a biological

    width). The flap for this procedure could be a one-tooth flap with two adjacent verticalreleasing incisions.

    When the tooth will be treated with a Class IIrestoration or a full-coverage crown, the inter-proximal bone may need to be resected. In thisevent, the dentist resects interproximal bone toestablish a distance associated with healthbetween the restorative margin and the new,more apical level of bone. As a result, the inter-proximal bone is apical to the facial and lingualbone. The dentist, having created reverse archi-tecture, needs to evaluate the second dimension,the mesiodistal dimension. To reestablish positivearchitecture, the dentist would need to resectfacial and lingual bone mesial and distal to theinterproximal area.

    The third dimension to osseousresection is the buccolingual dimen-sion. Periodontal biotype is relatedto thickness of periodontal tissues.Thick biotypes may consist of thickbone, thick soft tissue or both. Afterelevating the flap, the dentist maynote an osseous ledge or exostosis.Thick bone often occurs on thepalatal aspect of the maxillarymolar dentition.29 It also can be pre-sent on the lingual border of the

    mandible.30 Horning and colleagues31 examined 52modern skeletal specimens and reported buccalalveolar bone enlargements associated with 25percent of all teeth examined. Reduction ofosseous ledging or an exostosis via osteoplastywas recommended originally by Schluger32 in1949 and subsequently by Friedman33 in 1955. Itis our opinion that reduction of alveolar boneenlargements reduces the risk of postoperativerebound of soft tissue.

    In an esthetic crown-lengthening procedure,bone removal plays an important role in the finallocation of the free gingival margin after healing.Coslet and colleagues34 described the clinical cir-cumstance known as “delayed passive eruption.”In this condition, excess gingiva covers theanatomical crown, thereby resulting in a shortclinical crown. The classification system describedby the authors indicated that in some cases, whengingiva is significantly coronal to the CEJ, theosseous crest may be located at or within closeproximity to the CEJ. For a predictable outcomein these cases, flap elevation with access to thefacial osseous crest enables the dentist to visu-

    In an esthetic crown-lengtheningprocedure, boneremoval plays an

    important role in thefinal location of thefree gingival margin

    after healing.

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    alize and resect an appropriate amount of bone. Altered passive eruption also can be observed

    in the posterior sextants. The clinical crowns ofthe posterior dentition can be significantlyshorter than the anatomical crowns. In cases inwhich fixed prosthetic therapy is needed, reposi-tioning the free gingival margin to the level of theCEJ may be all that is necessary to expose cariesand establish cleansable gingival embrasureareas.35 The effect on periodontal support is negli-gible in these cases, as the resection of soft tissueand bone essentially is the resection of excessperiodontal tissues.

    Contraindications to osseous resection.Ostectomy becomes a liability when the stabilityof the treated dentition may be affected. Gener-ally, dentists should refrain from excessiveosseous removal if it will compromise the crownto root ratio. In addition, removal of bone in thefurcation region associated with the root trunk isa concern.36 The dentist also should avoidremoving bone in the furcation area.37

    Wound healing. After the surgical procedureconcludes, the healing phase begins. Research hasshown that when the clinician creates an apicallypositioned flap with an osseous resection pro-cedure, the biological width reestablishes itself at

    an apical level.38 Researchershave observed that if themargin of the flap is posi-tioned at the level of theosseous crest, a postoperativevertical gain or rebound insupracrestal soft tissuesoccurs that averages 3 mm.39,40

    If the flap margin is placed ata level more coronal to thenewly established osseouscrest, less vertical gain orrebound in supracrestal softtissues has been observed.41

    After a crown-lengtheningprocedure, a common questionpertaining to restorative orprosthetic treatment regardswhen the final tooth prepara-tion can begin and whenimpressions, if needed, can betaken. A key determinant forinitiating prosthetic therapyis the final position of the freegingival margin. This is par-ticularly true in cases in

    which the treated dentition is of esthetic concernto the patient.

    Lanning and colleagues42 demonstrated thatcoronal advancement of the healing tissues fromthe osseous crest averages 3 mm by three months’time after surgery. They also determined that sixmonths after surgery, no further significantchanges in the vertical position of the free gin-gival margin were apparent. Brägger and col-leagues43 also noted that during a six-monthhealing period after crown lengthening, perio-dontal tissues were stable, with minimal changesin the level of the gingival margin. From thesefindings, one can conclude that regarding finalprosthetic treatment in the esthetic zone, thewaiting period after a crown-lengthening pro-cedure should be six months.

    DISCUSSION

    Crown-lengthening surgery is a resective procedureused to induce recession surgically. To do so, theclinician either excises or apically positions soft tis-sues. In addition, the underlying osseous structureplays a critical role in the final wound healing.When osseous deformities already are present,osseous resection and apically positioned flapswould have the dual advantage of reducing probing

    Figure 2. Tooth no. 4 prepared for a full-coverage crown. Supragingival tooth struc-ture is not visible, and there is no ferrule.

    Figure 3. Pretreatment radiograph of tooth no. 4. Teeth nos. 3 and 4 had undergoneendodontic therapy.

    Figure 4. After flap elevation and before resection, the buccal osseous morphologyis exposed.

    Figure 5. Buccal view after osseous resection.Tooth structure is exposed to establish a biologicalwidth and ferrule length.

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    C O V E R S T O R Y

    depths and exposing toothstructure for restorativetherapy. Modification of themorphology of the under-lying bone must be evalu-ated in three dimensions.With respect to proximallesions or full-coverage restorations, crown-lengthening surgeryinvolves changes in themesiodistal dimension toestablish positive architec-ture. As a result of the needto dissipate the changes inthe hard and soft tissues ofthe adjacent teeth, length-ening the crown of onetooth with a proximal lesionessentially becomes a three-tooth surgery.

    With respect to pros-thetic therapy, crownlengthening results inmore cleansable gingivalembrasure areas adjacentto full-coverage crowns.Moreover, this procedurecan enable the clinician toestablish a biological widthand a ferrule length.Obtaining adequate expo-sure to establish both ofthese parameters shouldbe weighed against thepossibility of compromisingthe osseous support of thetooth undergoing crownlengthening, the osseoussupport associated with the adjacent teeth or both.

    Regarding initiation of final prosthetic treat-ment, researchers have observed an average ver-tical growth of 3 mm of supraosseous gingiva.39,40

    The final position of the free gingival margin canoccur at three months after surgery but mayoccur as long as six months after surgery. Fortreated areas in the esthetic zone, a waitingperiod of six months is advisable.

    CASE REPORT

    A 58-year-old woman in good health had a sub-gingival foundation restoration associated withtooth no. 4 (Figure 2). A preoperative radiograph

    indicated that endodontic therapy had been per-formed in conjunction with placement of a post-and-core foundation restoration. A periapicalradiograph indicated that the root length asso-ciated with tooth no. 4 appeared to be adequate toallow for osseous resective therapy (Figure 3).

    As adequate root length was available, and aferrule was not present, the clinician decided toperform a crown-lengthening procedure. Figures4 and 5 show the flap extending from the distalaspect of tooth no. 3 to the mesial line angle oftooth no. 6. These images display the osseouslevels before osseous resection. The clinician notedthat the length of supraosseous tooth structure

    Figure 6. Bone architecture after elevation of apalatal flap and before osseous resection.

    Figure 7. Palatal view of osseous morphology after osseous resection. Positivearchitecture is established at an apical level.

    Figure 10. Buccal view of the maxillary right pos-terior sextant eight years after periodontal andprosthetic treatment. Teeth nos. 3 and 4 have beenrestored with porcelain-fused-to-metal restorations.

    Figure 11. Radiograph of teeth nos. 3, 4 and 5 eight years after treatment with a crown-lengthening procedure and placement offull-coverage crowns.

    Figure 8. View of apically positioned buccal flapsutured with periosteal sutures.

    Figure 9. Buccal view eight weeks aftercrown-lengthening surgery. Periodontal tis-sues still are healing. Plaque-control measuresneed to be reviewed with the patient.

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    was inadequate for establishment of a biologicalwidth or ferrule.

    The clinician performed osseous resection,establishing 4.5 mm of supraosseous tooth struc-ture on the buccal and palatal aspects of tooth no. 4. In addition, the clinician attained positiveosseous architecture that extended from thedistal aspect of tooth no. 3 to the mesial aspect oftooth no. 5. Figures 6 and 7 show the area afterthe osseous resection. After completing osseoustherapy, the clinician positioned the flaps apicallyby means of periosteal sutures (Figure 8). Thistype of sutured closure attaches the flap at anapical level to connective tissue still present onthe facial aspect of the buccal bone (as describedby Kramer and colleagues44).

    Figure 9 shows additional exposure of toothstructure at eight weeks after the procedure. Atthree months after surgery, the patient returnedto the restorative dentist for fabrication of full-castrestorations associated with teeth nos. 4 and 3.Figure 10 is a photograph and Figure 11 a radio -graph of the restored area eight years after treatment.

    CONCLUSION

    Crown-lengthening surgery can be a viable optionfor facilitating restorative therapy or improvingesthetic appearance. When planning a crown-lengthening procedure, the dentist should eval-uate the patient’s complete periodontal conditionand disclose all possible treatment options to thepatient. In cases involving the possibility of a neg-ative esthetic outcome, compromise to the supportof the dentition involved in the surgical procedureor both, extraction and implant therapy or con-ventional prosthetic therapy may be a more com-pelling solution. ■

    Disclosure. Drs. Hempton and Dominici did not report any disclosures.

    The authors thank Dr. Jeffrey Harrison, Wellesley, Mass., for theprosthetic therapy provided in the clinical case presented in thisarticle.

    1. Allen EP. Surgical crown lengthening for function and esthetics.Dent Clin North Am 1993;37(2):163-179.

    2. McGuire MK. Periodontal plastic surgery. Dent Clin North Am1998;42(3):411-465.

    3. Hempton TJ, Esrason F. Crown lengthening to facilitate restora-tive treatment in the presence of incomplete passive eruption. J CalifDent Assoc 2000;28(4):290-291, 294-296, 298.

    4. Tarnow DP, Magner AW, Fletcher P. The effect of the distancefrom the contact point to the crest of bone on the presence or absence ofthe interproximal dental papilla. J Periodontol 1992;63(12):995-996.

    5. Gargiulo A, Wentz F, Orban B. Dimensions and relations of thedentogingival junction in humans. J Periodontol 1961;32:261-267.

    6. Vacek JS, Gher ME, Assad DA, Richardson AC, Giambarresi LI.The dimensions of the human dentogingival junction. Int J Perio-

    dontics Restorative Dent 1994;14(2):154-165.7. Ingber JS, Rose LF, Coslet JG. The “biologic width”: a concept in

    periodontics and restorative dentistry. Alpha Omegan 1977;70(3):62-65.8. Nevins M, Skurow HM. The intracrevicular restorative margin, the

    biologic width, and the maintenance of the gingival margin. Int J Perio-dontics Restorative Dent 1984;4(3):30-49.

    9. Günay H, Seeger A, Tschernitschek H, Geurtsen W. Placement ofthe preparation line and periodontal health: a prospective 2-year clin-ical study. Int J Periodontics Restorative Dent 2000;20(2):171-181.

    10. Parma-Benfenali S, Fugazzoto PA, Ruben MP. The effect of restora-tive margins on the postsurgical development and nature of the peri-odontium: part I. Int J Periodontics Restorative Dent 1985;5(6):30-51.

    11. The glossary of prosthodontic terms. J Prosthet Dent 2005;94(1):38.12. Sorensen JA, Engelman MJ. Ferrule design and fracture resis-

    tance of endodontically treated teeth. J Prosthet Dent 1990;63(5):529-536.

    13. Wagenberg BD, Eskow RN, Langer B. Exposing adequate toothstructure for restorative dentistry. Int J Periodontics Restorative Dent1989;9(5):322-331.

    14. Libman WJ, Nicholls JI. Load fatigue of teeth restored with castposts and cores and complete crowns. Int J Prosthodont 1995;8(2):155-161.

    15.Al-Hazaimah H, Gutteridge DL. An in vitro study into the effect ofthe ferrule preparation on the fracture reisistance of crowned teethincorporating prefabricated post and composite core restoration. IntEndodontic J 2001;34(1):40-46.

    16. Meng Q-F, Chen Y-M, Guang H-B, Yip KH-K, Smales RJ. Effectof a ferrule and increased clinical crown length on the in vitro fractureresistance of premolars restored using two dowel-and-core Systems.Oper Dent 2007;32(6):595-601.

    17. Morgano SM, Brackett SE. Foundation restorations in fixedprosthodontics: current knowledge and future needs. J Prosthet Dent1999;82(6):643-657.

    18. Gegauff AG. Effect of crown lengthening and ferule placement onstatic load failure of cemented cast post-cores and crowns. J ProsthetDent 2000;84(2):169-179.

    19. Research, Science and Therapy Committee of the AmericanAcademy of Periodontology. Lasers in periodontics. J Periodontol 2002;73(10):1231-1239.

    20. Maynard JG, Wilson RD. Physiologic dimensions of the periodon-tium significant to the restorative dentist. J Periodontol 1979;50(4):170-174.

    21. Nabers CL. Repositioning the attached gingiva. J Periodontol1954;25:38-39.

    22. Ariaudo A, Tyrrell HA. Repositioning and increasing the zone ofattached gingiva. J Periodontol 1957;28:106-110.

    23. Pippin DJ. Fate of pocket epithelium in an apically positionedflap. J Clin Periodontol 1990;17(6):385-391.

    24. Garber DA, Salama H, Salama MA. Multidisciplinary cases:lessons learned. Paper presented at: 24th Annual Meeting of theAmerican Academy of Esthetic Dentistry; Whistler, British Columbia,Canada; Aug. 6, 1999.

    25. Matherson DG. An evaluation of healing following periodontalosseous surgery in monkeys. Int J Periodontics Restorative Dent 1988;8(5):9-39.

    26. Kaldahl WB, Kalkwarf KL, Patil KD, Molvar MP, Dyer JK. Long-term evaluation of periodontal therapy, II: incidence of sites breakingdown. J Periodontol 1996;67(2):103-108.

    27. Olsen CT, Ammons WF, van Belle G. A longitudinal study com-paring apically repositioned flaps, with and without osseous surgery.Int J Periodontics Restorative Dent 1985;5(4):1-33.

    28. Kaldahl W, Kalkwarf K, Patil K, Dyer J, Bates R. Long-termevaluation of periodontal therapy, I: response to 4 therapeutic modali-ties. J Periodontol 1996;67(2):93-102.

    29. Nery EB, Corn H, Eisenstein IL. Palatal exostosis in the molarregion. J Periodontol 1977;48(10):663-666.

    30. Sonnier KE, Horning GM, Cohen ME. Palatal tubercles, palataltori, and mandibular tori: prevalence and anatomical features in a U.S.population. J Periodontol 1999;70(3):329-336.

    31. Horning GM, Cohen ME, Neils TA. Buccal alveolar exostoses:prevalence, characteristics, and evidence for buttressing bone forma-tion. J Periodontol 2000;71(6):1032-1042.

    32. Schluger S. Osseous resection: a basic principle in periodontalsurgery. Oral Surg Oral Med Oral Pathol 1949;2(3):316-325.

    33. Friedman N. Periodontal osseous surgery: osteoplasty and ostec-tomy. J Periodontol 1955;26:257-259.

    34. Coslet JG, Vanarsdall R, Weisgold A. Diagnosis and classificationof delayed passive eruption of the dentogingival junction in the adult.Alpha Omegan 1977;70(3):24-28.

    Copyright © 2010 American Dental Association. All rights reserved. Reprinted by permission.

    on June 20, 2010 jada.ada.org

    Dow

    nloaded from

    http://jada.ada.org

  • JADA, Vol. 141 http://jada.ada.org June 2010 655

    C O V E R S T O R Y

    35. Malament KA. Considerations in posterior glass-ceramic restora-tions. Int J Periodontics Restorative Dent 1988;8(4):32-49.

    36. Dilbart S, Capri D , Kachouh I, Van Dyke T, Nunn ME. Crownlengthening in mandibular molars: a five-year retrospective radio -graphic analysis. J Periodontol 2003;74(6):815-821.

    37. Ochsenbein C. A primer for osseous surgery. Int J PeriodonticsRestorative Dent 1986;6(1):8-47.

    38. Oakley E, Rhyu IC, Karatzas S, Gandini-Santiago L, Nevins M,Caton J. Formation of the biologic width following crown lengtheningin nonhuman primates. Int J Periodontics Restorative Dent 1999;19(6):529-541.

    39. Pontoriero R, Carnevale G. Surgical crown lengthening: a 12-month clinical wound healing study. J Periodontol 2001;72(7):841-848.

    40. Perez JR, Smuckler H, Nunn ME. Clinical evaluation of the

    supraosseous gingivae before and after crown lengthening. J Perio -dontol 2007;78(6):1023-1030.

    41. Deas DE, Moritz AJ, McDonnell HT, Powell CA, Mealey BL.Osseous surgery for crown lengthening: a 6-month clinical study. JPeriodontol 2004;75(9):1288-1294.

    42. Lanning SK, Waldrop TC, Gunsolley JC, Maynard JG. Surgicalcrown lengthening: evaluation of the biological width. J Periodontol2003;74(4):468-474.

    43. Brägger U, Lauchenauer D, Lang NP. Surgical lengthening of theclinical crown. J Clin Periodontol 1992;19(1):58-63.

    44. Kramer GM, Nevins M, Kohn JD. The utilization of periostealsuturing in periodontal surgical procedures. J Periodontol 1970;41(8):457-462.

    Copyright © 2010 American Dental Association. All rights reserved. Reprinted by permission.

    on June 20, 2010 jada.ada.org

    Dow

    nloaded from

    http://jada.ada.org