Oral Surgery

Alternative treatments for a traumatic bone cyst:A longitudinal case reportTracy M. Dellinger, DDS*/Ray Holder, MS, DMD**/H. Mark Livingstoti,Willie J, Hill, DDS****

A patient presented with a large, inultilocidar, refractory traumatic bone cyst. The radiolucency had in-creased in dimension since her last recall. Over ¡ I years, therapy had included needle aspiration biop-sies followed by simple curettage and closure, the most common therapy for traumatic bone cysts.However, all treatment had proved unsuccessful for this patient. It was decided to treat tiie patient with aslightly unique method. After curettage of the iesiiin, the traumatic bone cy.îf was packed with a mixmieof autogenous blood, harvested autogenous bone diips, and hydroxyapatite. (Quintessence Int I998-29-497-502)

Key words: altemative treatments, curettage, florrid osseous dysplasia. hard tissue lesions, traumaticbone cyst

Traumatic bone cysts were first noted in the literaturein 1929 but were considered quite rare until com-

mon use of panoramic radiographs demonstrated an in-creased frequency of this benign lesion.'- Traumaticbone cysts are normally associated with the posteriormandible but on rare occasion involve the maxilla.-Patients are usually in their second decade; males ex-hibit a slightly higher predilection than females. The pa-tient usually presents with a history of trauma to thejaws. Radiographie examination reveáis a unilocular orniultilocular, well-delineated radioliicency with scal-loped margins that extend between the roots of teeth.The size and shape of the lesion may vary. There is

•Denial Research E-"eI)ow, Deparimeni of Veterans Affairs, Jackson.Mississippi.

**Assatiale Professor and Director, Advanced Education in DentistryResidency, University of Mississippi, School of Denlistry, Jackson.Mississippi.

'•'Assistant Professor, Department of Restorative Dentislry, Universityof Mississippi. School of Denlistry, Jackson, Mississippi.

•••••Professor and Chairman, Department of Oral and MaxillofacialSurgery, University of Mississippi, School of Dentistry, Jackson,Mississippi.

Reprint requesis; Dr Tracy M. Deilinger, University of Mississippi,School of Dentislry, CDRC Room D-202, 2500 North State Street.Jackson. Mississippi 39215. E-mail: den[al96@aoLcom

This article is a work of Ihe US governmeni and may he reprinted withoutpermission. The opinions or assertions contained herein are private viewsof the authors and are not to be conslrued as official or as reflecting theviews of the Department of Veterans Affairs or any other department oragency of the US government.

rarely displacement of the involved dentition or expan-sion of the involved cortical plate in this condition.'' Thelesion does not affect the vitality of the involved denti-tion.' However, an interesting patient subset was identi-fied: There is a tendency for traumatic hone cysts topresent at multiple sites in older black women.* Ad-ditionally, the simultaneous occurrence of simple bonecysts and florid osseous dysplasia has heen reported.^'

The term traumatic bone cyst is a misnomer hecauseno epithelial lining is associated with the lesion. Moreappropriately, it might be referred to as an idiopathicbone cavity, but the terms solitary bone cyst, hemor-rhagic cyst, extravasation cyst, unicameral bone cyst.and simple bone cyst have all been used to describe thisphenomenon/ Diagnosis cannot truly he establisheduntil the lesion has been exposed by surgical access,whereupon usual findings include the lack of an epithe-lial lining, walls of histologically normal bone sur-rounding the cavity, and a space commonly devoid ofany visible contents except for a minimal amount ofvariously colored fluid.^''

The etiology of the traumatic bone cyst is unknownbut may be related to trauma.'' Heubner and Turlington-delineated the following probable causes: (1) trauma,resulting in intramedullary hemorrhage; (2) infarctionof bone marrow or cancellous bone; <3) loss of theblood supply of" a hemangioma. a lymphangioma, or anangiomatous cyst; (4) cystic degeneration of tumors; (5)blockade of osteogenic activity; (6) cystic areas of focalinfection that result from their being "walled-off ' and

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Fig 1 A mixed radiopaque-radioiuoent iesion is associated withthe mandibuiar teeth, from the iett second premoiar to the rightcanine (1984).

Fig 2 A definitive, multilocular mixed lesion extends from the dis-tal aspect of the left second premolar to the right first premolar(1990].

graduaily imbibing tluid; and (7) faulty caicium nietab-oiism. Unfortunately, research has .still not pinpointedthe mechanism for traumatic hone cyst formation.Although traumatic hone cysts are benign, resolution ofthe lesion is preferred.

In the foilowing case, a patient presented to the clinicwith a large, multilocular traumatic bone cyst. This caseis quite informative because serial examinations andradiographs aiiowed a longitudinal evaluation of theprogression ofa traumatic bone cyst.'"

Case report

A 51-year-old black woman first came to the Universityof Mississippi School of Dentistry in 1984 for treatmentplanning and oral heaith care. The only .significant med-ical history included medically treated hypertension andhormone replacement therapy for her postmenopausaistatus. At this time, a panoramic radiograph was taken(Fig I): however, no notation was made concerning themixed radiolucent-radiopaque area in the mandibie. Shewas then treated with periodontal therapy, restorafions,maxillary fixed partial dentures, muitiple extractions,and a mandibular removable partial denture. An oral hy-giene recall protocol was recommended.

The pafient decided !o seek outside dental care forthe next 3 years. She returned to the clinic in 1990 withthe compiaint of paresthesia on the left side of themandible following extraction of her mandibular leftsecond molar by a private dentist. The clinical examina-fion showed the mandible to be enlarged in the area ofthe left alveolar ridge. A panoramic radiogtaph was thentaken, and a large multilocular mixed iesion involvingall mandibular anterior teeth was identified (Fig 2). The

mandibular teeth all tested vital utilizing electric pulptester (EPT), coid, and heat. The oral surgery and oralpathology attending faculty were then consulted, andthe patient was rescheduled for biopsy. At this time, thedifferentiai diagnosis included periapical cémentai dys-plasia. fiorid osseous dyspiasia, fibrous dysplasia, cen-trai ossifying or cementifying fihroma. calcifying ep-itheiial odontogenic cyst (Gorlins cyst}, calcifyingepithelial odontogenic tumor (Pindborg tumor), odonto-genic keratocyst. and centrai giant-cell granuloma.'**

The patient presented for biopsy of the lesion. Asmall amount of straw-coiored exúdate was aspirated; ithad a negative culture. A mucogingival flap was re-flected, and access to the lesion was made through thethin cortical bone. The cavily was hollow, held a smallamount of straw-colored fluid, and had bony walls. Theiesion was curetted on both sides of the mandibularmidline, and the gingival fiap was ciosed. It was deter-mined on exarnination that the lesion was a traumaficbone cyst and idiopathic bone cavity (Fig 3). The pa-tient was released without complications with a pre-scription for antibiotics and pain medication. Sutureswere removed 1 week later, and the pafient's soft tissuewas healing without compiication.

The pafient was recalled 6 months later; a panoramicradiograph revealed some radiopaque fill in the area(Fig 4). The patient was monitored for 2 years, andthere was no additionai bone formation in the defect(Fig 5). In fact, the radiolucency had extended its bor-ders along the right mandihie to include the region be-tween the left second premolar and right second premo-lar. It was decided to reenter the bone cavity in 1993and the same procedure and protocols previously dis-cussed were followed.

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Fig 3 in 1991 the lesion was accessed and diagnosed as a trau-matic bone cyst. The lesion consists of a hoiiow cavity surroundedby bony walis. No epitheiial iining is present. A small amount ofstraw-coiored fiuid was aspirated.

Fig 4 From 1991 to 1993, the patient's traumatic bone cyst wasmonitored on a 6-month recaii system.

Fig 5 An additionai radiograph reveáis increased radiopacity onthe ieft borde' oí the iesion and the continued focal areas ofradiopacity within the lesion, most significantiy from the left iateraiincisor to the right first premolar (1991).

Fig G The mandibular anterior lesion has increased in both di-mension and radiolucency ¡1996). At this time, alternative therapywas pianned.

The patient continued to attend her recall oral hy-giene appointments. In 1996, the patient complained ofcontinued pare.sthesia in the left mandihie. The patientmaintained excellent oral hygiene and had minimalplaque and calculus accumulation. Also, during prophy-laxis, the hygienist noted moderate tooth mohility gen-eralized throughout the mandibular dentition. The hy-gienist brought the patient to the graduate program forevaluation.

Oral examination verified expansion of the buccalplate of the anterior mandible. All mandibular teethdemonstrated +2 mobility and tested vital (utilizingEPT, cold, and heat stimuli). A panoramic radiograph(Fig 6) and assorted periapical radiographs were taken.The radiographs showed the radiolucent area depictedin Fig 4. It was determined and explained to the patient

that a more aggressive therapy than the conventionalcurettage would be used to treat the lesion after a finalbiopsy confirmed that the lesion was, as originally diag-nosed, a traumatic bone cyst.

The patient was brought to the oral surgery clinic. Asmall amount of straw-colored exúdate, which con-tained white and red blood cells, was withdrawn; how-ever, the cavity appeared to he hollow. After a mucogin-gival flap was reflected to reveal the huccal surface ofthe anterior mandible, a small window was placedthrough the thin cortical plate to gain access to the le-sion. The lesion did not appear to have any type of epi-thelial lining, only thin hony margins. An interesting,but expected, finding was that the mandihular canal wasnot contained within the traumatic hone cyst. The infe-rior alveolar nerve was intact but was more lingually

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Fig 7 The radiopaque mixture placed during oral suigery con-tains both autogenous har iested bone chips and h yd roxy apatitemixed with autogenous blood (1997)

Fig 8 A 6-month pos'.optjra'.ije panoramic radiograph reveáisgeneraiized increased radiopacity, less delined borders, and re-turn of trabeculation within the iesiûn site.

positioned than expected, possibly accounting for theparesthesia the patient had been experiencing in her leftmandible. After curettage, the lesion was closed, and thepatient was given prescriptions for antibiotics and painmedication.

The patient returned to the clinic 1 week later for su-ture removal. At this time, it was discovered that the en-tire mandibular anterior .segment that was involved withthe lesion had depressed the involved teeth approxi-mately 1.5 mm, further demonstrating that the thin re-maining bone was not able to distribute stress in the af-fected load-h earing regions.

The patient was administered a local anesthetic. Amucogingival flap across the mandibular anterior mid-line was reflected. A window was made by inserting anosteotome into the lesion; this window was enlarged uti-lizing rongeurs to gain access to all bony margins of thetraumatic bone cyst. The cavity was then thoroughlycuretted. Most of the hone fragments were left withinthe cavity. However, a few fragments were removed andplaced aside for later use.

Approximately 5 mL of whole blood was withdrawnfrom the patient's right antecuhital region. The hloodwas mixed with 6 mL of hydroxyapatite and the honefragments that had heen set aside earlier. This mixturewas gently injected into the mandibular cavity to slightexcess. The mucogingival flap wa.s replaced, and inter-rupted silk sutures were used for primary closure. Apanoramic radiograph confirmed the piacement of theinjected mixture in the hone cavity (Fig 7). The patientwas prescribed a 7-day course of 5Û0 rng penicillin VK,taken every 6 hours, to prevent postoperative infection.

The patient returned for postoperative evaluation 1week following the oral surgery. The patient stated thatshe could detect additional sensation in her left lower

lip and cheek, which was confirmed by pain stimuli;however, sensation remained altered. The mucogingivalflap had healed within normal parameters, and the su-tures were retnoved. A 0.12% chlorhexidine regimenwas prescrihed. The patient was asked to return in 6 toS weeks for radiographie evaluation of the traumatichone cyst.

Six months after the surgical treatment of the bonecyst, the patient reported back to the dental clinic for afollow-up evaluation and recall visit. She reported con-tinued improved sensation in her left cheek and lowerlip, which she referred to as "'feeling normal." Intraoralexamination revealed a well-healed surgical site with-out abnormalities. Probing depths had remained un-changed since the last visit; however, mobility hadgreatly decreased and only two teeth exhibited greaterthan normal movement. A panoramic radiograph re-vealed an increased radiopacity within the lesion site,less defined borders of the traumatic bone cyst, sfightdiffusion of the hydroxyapaiite-blood mixture withinthe cavity, and return of defined landmarks within thearea (mainly the mandibular canals and tnental fora-men) (Fig 8).

Discussion

Following the ftrst mandibular biopsy of the patient in1990, confirming the diagnosis of a traumatic bone cyst,florid osseous dysplasia (FOD) remained a possihle un-derlying condition that required further considerafion.Florid osseous dysplasia, also identified as focalcemento-osseous-dysplasia. is a condition characterizedby a primary osteolytic phase, typified by a radiolucentradiographie appearance, and then followed by a mixedradiolucent and opaque lesion of the jaws." Florid

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osseous dysplasia is usually located in the mandibularanterior region when identified in its target population,hlack women over the age of 40 years,'"

In 1984. the patient first presented with the nnixed le-sion in the anterior portion of her mandible. However,longitudinal panoramic films revealed that the lesionnol only increased dramatically in the radiolucent com-ponent but also expanded in size. A second difference isthe contents; this lesion contained a straw-colored exú-date, whereas the content. of an FOD lesion typicallyinclude a fibrous stroma, irregular hony traheculac, andcementumlike material.'"

Various authors have reported traumatic bone cystsassociated with FOD but all mention that this is a rarefinding.'-'-'^ These studies suggest that simple bonecysts associated with FOD may have a different etiol-ogy than bone cysts not associated with this ahnormal-ity_7,12.13 One theory suggests that local bone destructionwithin the traumatic bone cyst may be secondary to ob-struction of interstitial fluid drainage, thus leading tocyst formation.'-

By itself, FOD is a benign condition rarely requiringsurgical intervention because of its self-limiting nature;however, traumatic bone cysts are commonly treatedsurgically because of their tendency to expand andcause pathologic fractures.^" In addition, among 34 pa-tients with florid osseous dysplasia. traumatic bonecysts were found in 14; three of the patients attainedonly partial resolution of the cysts following conven-tional surgical curettage.'-'''

It is important that the pathogenesis of a solitarybone cyst, either unicameral or traumatic bone cy,sts, beclarified for its treatment to be effective; however, thepathogenesis is stiil unknown and speculative.'^ Themost common therapy for bone cysts con,sists of simplecurettage and closure, which induces hemorrhage intothe defect. Osteohlastic activity typically initiatesmesynchymal cells found in the autogenous blood todifferentiate into cells with osteogenic potential.'Complete resolution of the defect via bony regenerationusually occurs within a short period following curet-tage.'-* This therapy had proved unsuccessful for thispatient, as demonstrated by the results from the proce-dures performed in 1990 and 1993. Although someosteoblastic activity may have been initiated by theconventional therapy, resolution of the lesion wasincomplete.

To date, there have been several documented casesof "suspected recurrence" of traumatic bone cysts fol-lowing curettage; however, the lesions were actually re-fractory to resolution via the traditional surgical ther-apy.'"'After traditional bone cyst therapy has provedunsuccessful, other treatment options have included the

placement of freeze-dried homographs of caneellousbone chips with traditional curettage and closure,'' theplacement of hydroxyapatite in the lesion after curet-tage.'" packing the cyst cavity with a thrombin-penicillin-impregnated Gelfoam," or the injection of asmall amount of autogenous hlood into the cyst cavityduring traditional therapy, as discussed by Precious andMcFadden.' All of or each of these therapies led to suc-cessful resolution of their respective lesions, whichwere refractory to conventional therapy. It was decidedto perform a comhination of some of the aforemen-tioned techniques for this aggressive hard tissue lesion.

Whole blood contains the progenitor cells necessaryfor osteogenesis.'" An injection into the bone defect ofatJtogenous blood mixed witb bone cbips from tbecurettage of a bone cyst provides osteoinductivepropetlies to instigate osteoblast activity so tbat boneformation ultimately occurs within the cavity. Hydroxy-apatite. a bioactive ceramic, bas been reported as an ef-fective osteoconductive impetus tbat encourages newbone formation witbin tbe cavity."''''--^ Additionally,hydroxyapatite has been mixed with autogenous bonegraft to furtber ensure osteogenic activity within bonedefects. '"

Conclusion

It was theorized that the combination of the osteocon-ductive forces of hydroxyapatite and the osteoinductiveabilities of autogenous blood and bone would providean optimal environment for bone regeneration. Initialresults seem promising. The bone density increasedwithin the site of the traumatic bone cyst, and the denti-tion exhibited decreased mobility.

Although there has not been any scientific evidencestibstantiating the patient's anecdotal claim of increasedsensation in tbe lower lip to be associated with the reso-lution of the traumatic bone cyst, it is possible that thelack of bony support surrounding the inferior alveolarnerve did cause some altered sensation. Along the samereasoning, it is possihle that the added bone formationrelieved mechanical stress. Possible etiologies of me-chanical stress include impingement of the inferior alve-olar nerve and occlusion of the associated vessels, re-sulting in ischemia to the distal portion of the nerve. Itis possihle that once mechanical support to the nerveand associated vessels was returned, normal conductionof sensations resumed.

The patient will be monitored every 6 months to fol-low the progression of healing. Recurrence of thetraumatic bone cyst is not expected; however, con-sidering the patient's histor>', periodic oral evaluation iswarranted.

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