CAROL ANNE MURDOCH-KINCH · dentition. Management The craniofacial features of Crouzon syndrome worsen over time because of the abnormal craniofacial growth. Early diagnosis permits

CAROL ANNE MURDOCH-KINCH

and soft palate in the most severe cases. CP developsfrom a failure of fusion of the lateral palatal shelves.The minimal manifestation of cleft palate is a submu-cous cleft. Here, the palate appears to be intact, exceptfor notching of the uvula (bifid uvula) or notching inthe posterior border of the hard palate detectable bypalpation. The most severe presentation is completeclefting of the hard and soft palate. The precise etiol-ogy of orofacial clefting is not completely understood.However, most cases of CLIP and CP are considered tobe multifactorial with a strong genetic component.CLIP and CP can each be associated with other, abnor-malities, as part of a genetic malformation syndr~mesuch as velocardiofacial syndrome (del 22q.ll syn-drome-cleft palate, facial and cardiac abnormalities)or van der Woude syndrome (cleft lip andl or cleftpalate and lip pits). Other factors that are implicated inthe development of orofacial clefts include nutritionaldisturbances (prenatal folate deficiency); environ-mental teratogenic agents (maternal smoking, in uteroexposure to anticonvulsants); stress, which results inincreased secretion of hydrocortisone; defects of vascu-lar supply to the involved region; and mechanical inter-ference- with the closure of the embryonic processes(cleft palate in Pierre Robin sequence). Clefts involvingthe lower lip and mandible are extremely rare.

I evelopmental disturbances affect the normal

growth and differentiation of craniofacial

structures. As a consequence, they are usually first dis-covered in infancy or childhood. Many of the condi-tions discussed in this chapter have an unknownetiology. Some are caused by known and recently dis-covered genetic mutations, whereas others result fromenvironmental factors. These conditions result in avariety of abnormalities of the face and jaws, includingabnormalities of structure, shape, organization, andfunction of hard and soft tissues.

A multitude of conditions exist that affect the mor-phogenesis of the face and jaws, many of which are raresyndromes. This chapter briefly reviews the morecommon developmental abnormalities that may beencountered in dental practice.

DefinitionA failure of fusion of the developmental processes ofthe face during fetal development may result in a varietyof facial clefts. Cleft lip and cleft palate are the mostcommon developmental craniofacial anomalies. Cleftlip with or without cleft palate (CLIP) and cleft palate(CP) are two different conditions with different etiolo-gies. CLIP results from a failure of fusion of the medialnasal process and the maxillary process. This conditioncan range in severity from a unilateral cleft lip to bilat-eral complete clefting through the lip, alveolus, hard

Clinical Features # .

The frequency of CLIP and CP varies with gender andrace, but in general CLIP is most common in males,whereas CP is more common in females. Both condi-

639

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640 PART V RADIOGRAPHIC INTERPRETATION OF PATHOLOGY

tions are more common in Asians and Hispanics thanAfrican-Americans or Caucasians. The severity of CLIPvaries from a notch in the upper lip to a cleft involvingonly the lip to extension into the nostril, resulting indeformity of the ala of the nose. As CLIP increases inseverity, the cleft will include the alveolar process andpalate. Bilateral cleft lip is more frequently associatedwith cleft palate. CP also varies in severity, ranging frominvolvement of only the uvula or soft palate to exten-sion all the way through the palate to include the alve-olar process in. the region of the lateral incisor on oneor both sides. With involvement of the alveolar process,there is an increase in frequency of dental anomalies inthe region of the cleft including missing, hypoplastic,and supernumerary teeth, and enamel hypoplasia.Dental anomalies are also more prevalent in themandible in these patients. In both CLIP and CP thepalatal defects interfere with speech and swallowing.Affected individuals with palatal clefts are also atincreased risk for recurrent middle ear infectionsbecause of the abnormal anatomy and function of theeustachian tube.

Radiographic FeaturesThe typical appearance is a well-defined vertical radi-olucent defect in the alveolar bone, as well as numer-ous associated dental anomalies (Fig. 29-1). These mayinclude the absence of the maxillary lateral incisor andthe presence of supernumerary teeth in this region.Often the involved teeth are malformed and poorlypositioned. In patients with cleft lip and palate, theremay be a mild delay in the development of maxillaryand mandibular teeth, and an increased incidence ofhypodontia in both arches. The osseous defect mayextend to include the floor of the nasal cavity. Inpatients with a repaired cleft, a well-defined osseousdefect may not be apparent but only a vertically shortalveolar process at the cleft site.

BFIG. 29-1 Cleft palate results in defects in the alveolarridge and abnormalities of the dentition. A, Bilateral clefts ofthe maxilla in the lateral incisor regions and defects of thedentition. B, Lateral cephalometric view showing under-development of the maxilla.

normal arch form and functionalrecreateocclusion.

a

ManagementManagement of CLIP and CP is complex, requiringthe coordinated efforts of a multidisciplinary teamknow as a Cleft Palate Team. This team usually includesa plastic and reconstructive surgeon, oral and max-illofacial surgeon, ENT surgeon, orthodontist, dentist,speech therapist, psychologist, nutritionist, and socialworker. Clefts of the palate are usually surgicallyrepaired within the first year, whereas clefts of the lipare usually repaired within the first 3 months to aidin feeding and maternal/infant bonding. The bonein the cleft site is often augmented with bone graft-ing prior to replacement of missing teeth with eitherfixed or removable prosthodontics or dental im-plants. Orthodontic treatment is usually necessary to

SynonymsCraniofacial dysostosis, syndromic craniosynostosis,

premature craniosynostosis

DefinitionCrouzon syndrome (CS) is an autosomal-dominantskeletal dysplasia characterized by variable expressivityand almost complete penetrance. It is one of manydis-eases characterized by premature craniosynostosis(closure of cranial sutures). Its incidence is estimatedat 1/25,000 births. Of these cases, 33% to 56% mayarise as a consequence of spontaneo\.1s mutations, withthe remaining being familial. CS is caused by a muta-tion in fibroblast growth factor receptor II on chromo-some 10. Mutations at this site are alSQ responsible for


CHAPTER 29 DEVELOPMENTAL DISTURBANCES OF THE FACE AND JAWS 641

other craniosynostosis syndromes with similar facialfeatures but clinically visible limb abnormalities. Inpatients with CS the coronal suture usually closes first,and eventually all cranial sutures close early. Prematurefusion of the synchondroses of the cranial base alsooccurs. The subsequent lack of bone growth perpehdi-cular to the synchondroses and cranial coronal suturesproduces the characteristic cranial shape and facialfeatures.

smaller than normal but appears prognathic in relationto the severely hypoplastic maxilla.

Differential DiagnosisPremature craniosynostosis, either isolated or part of agenetic syndrome, is a fairly common disorder. Its inci-dence is reported to range from 1/2100 to 1/2500births. Other causes of craniosynostosis must be dif-ferentiated from Crouzon syndrome, including othersyndromic forms of craniosynostosis and nonsyn-dromic coronal craniosynostosis. The characteristicfacial features must be present to suggest Crouzonsyndrome.

Clinical FeaturesPatients characteristically have brachycephaly (shortanterior-posterior skull length), hypertelorism(increased distance betWeen eyes), and orbital propto-sis (protruding eyes) (Fig. 29-2, A and B). In familialcases, the minimal criteria for diagnosis are hyper-telorism and orbital proptosis. Patients may becomeblind as a result of early suture closure and increasedintracranial pressure. The nose often appears promi-nent and pointed because the maxilla is narrow andshort in a vertical and an anterior-posterior dimension.The anterior nasal spine is hypoplastic and retruded,failing to provide adequate support to the soft tissue ofthe nose. The palatal vault is high and the maxillaryarch narrow and retruded, resulting in crowding of thedentition.

ManagementThe craniofacial features of Crouzon syndrome worsenover time because of the abnormal craniofacial growth.Early diagnosis permits surgical and orthodontic treat-ment from infancy through -adolescence, coordinatedby a Craniofacial Team. The objectives of these treat-ments are to allow normal brain growth and develop-ment by preventing increased intracranial pressure, toprotect the eyes by providing adequate bony support,to provide an adequate airway, and to improve facialaesthetics and occlusal function. Because of early diag-nosis and improvements in medical and dental care,most patients have normal intelligence and can expecta normal lifespan.Radiographic Features

General radiographic features. The earliest radi-ographic signs of cranial suture synostosis are sclerosisand overlapping edges. Sutures that normally shouldlook radiolucent on the skull film will not bedetectable or will show sclerotic changes. Interestingly,on rare occasions the facial features may present priorto radiographic evidence of sutural synostosis. Prema-ture fusion of the cranial base leads to diminishedfacial growth. In some cases, prominent cranial mark-ings are noted, which are also seen in normal-growingpatients, but they are more prominent because of anincrease in intracranial pressure from the growingbrain. These markings may be seen as multiple radi-olucencies appearing as depressions (so-called digitalimpressions) of the inner surface of the cranial vault,which results in a beaten-metal appearance (Fig. 29-2,C-E).

Hemifacial Microsomia

SynonymsHemifacial hypoplasia, craniofacial microsomia, lateralfacial dysplasia, Goldenhar syndrome, oculo-auriculo-vertebral dysplasia

DefinitionHemifacial microsomia (HFM), the second mostcommon developmental craniofacial anomaly aftercleft lip and palate, affects 1/5600 live births. Patientswith HFM display reduced growth and development ofhalf of the face because of abnormal development ofthe first and second branchial arches. This malforma-tion sequence is usually unilateral but occasionally mayinvolve both sides (craniofacial microsomia). When thewhole side of the face is involved, the mandible,maxilla, zygoma, external and middle ear, hyoid bone,parotid gland, fifth and seventh cranial nerves, muscu-lature, and other soft tissues are diminished in size andsometimes fail to develop. Most case? occur sponta-neously, but familial cases have been reported. There isa male predominance of 3: 2 and a right side predom-inance of 3: 2. Cases with vertebral abnormalities and

Radiographic features of the jaws. The lack of growthin an anterior-posterior direction at the cranial baseresults in maxillary hypoplasia, creating a class III mal-occlusion in some patients. The maxillary hypoplasiacontributes to the characteristic orbital proptosisbecause the maxilla forms part of the inferior orbitalrim and, if severely hypoplastic, fails to adequatelysupport the orbital contents. The mandible is typically


c

A

D

B

FIG. 29-2 A and B, Characteristic facial features of Crouzon syndrome in this 2-year-old boy include orbital proptosis, hypertelorism, and midfacial hypoplasia. Rarely, they mayprecede the radiographic features of sutural synostosis. C, Crouzon syndrome results inearly closure of the cranial sutures and depressions (digital impressions) on the inner surf,a,eof the calvarium from growth of the brain. D and E, Closure of the cranial sutures in anotherpatient. Note also the prominent digital markings. (D and E, Courtesy Department of

Radiology, Baylor University Hospital, Dallas, Texas.)


643DEVELOPMENTAL DISTURBANCES OF THE FACE AND JAWSCHAPTER 29

epibulbar dermoids have been considered to form aseparate category within this condition, known as Gold-enhar syndrome or oculo-auricula-vertebral dysplasia.

thetics, and the hearing loss may be partly corrected byhearing aids.

Clinical FeaturesHemifacial microsomia is usually apparent at birth.Patients with this condition have a striking appearancecaused by progressive failure of the affected side togrow, which gives the involved side of the face a reduceddimension. In addition, aplasia or hypoplasia of theexternal ear (microtia) is common, and the ear canaloften is missing. In some patients the skull is dimin-ished in size. In about 90% of cases, there is malocclu-sion on the affected side. The midsagittal plane of thepatient's face is curved toward the affected side. Theocclusal plane will often be canted up to the affectedside.

SynonymMandibulofacial dysostosis

Definition

Treacher Collins syndrome (TCS) is an autosomal-

dominant disorder of craniofacial development. It is

the most common type of mandibulofacial dysostosis,

with an incidence of 1/50,000. TCS has variable expres-

sivity and complete penetrance. Approximately half of

cases arise as the result of sporadic mutation; the rest

are familial. TCS is caused by a mutation in the TCOF1

gene on chromosome 5.

Radiographic Features

The primary radiographic finding is a reduction in the

size of the bones on the affected side. This change is

clearest in the mandible, which may show a reduction

in the size of -or in severe cases, lack of any develop-

ment of-the condyle, coronoid process, or ramus. The

body is reduced in size, and a portion of the di$tal

aspect may be missing (Fig. 29-3). The dentition on the

affected side may show a reduction in the number or

size of the teeth. CT examination shows a reduction in

the size of the muscles of mastication and muscles of

facial expression, and hypoplasia or atresia of the audi-

tory canal and ossicles of the middle ear. The course of

the facial nerve is often shown to be abnormal on CT

examination of the temporal bone.

Clinical FeaturesIndividuals with Treacher Collins syndrome have a widerange of anomalies, depending on the severity of thecondition. The most common clinical findings are rel-ative underdevelopment or absence of the zygomaticbones, resulting in a small narrow face; a downwardinclination of the palpebral fissures; underdevelopmentof the mandible, resulting in a down-turned, widemouth; malformation of the external ears; absence ofthe external auditory canal; and occasional facial clefts(Fig. 29-4, A and B). The palate develops with a higharch or cleft in 30% of cases. Hypoplasia of themandible and a steep mandibular angle results in anAngle class II anterior open-bite malocclusion.Hypoplasia or atresia of the external ear, auditorycanal, and ossicles of the middle ear may result inpartial or complete deafness.

Differential DiagnosisThe features of hemifacial microsom"ia are characteris-tic. Condylar hypoplasia, especially that caused by afracture at birth or by juvenile arthrosis (Boering'sarthrosis), may be similar, but it does not produce theear changes (see Chapter 25). Exposure of the face ofa child to radiation therapy during growth also mayresult in underdevelopment of the irradiated tissues. Inprogressive hemifacial atrophy (Parry-Romberg syn-drome), changes will become more severe over time but.are generally not present at birth, and the ears arenormal.

Radiographic FeaturesA striking finding is the hypoplastic or missing zygo-matic bones, and hypoplasia of the lateral aspects of theorbits. The auditory canal, mastoid air cells, and artic-ular eminence often are smaller than normal or absent.The maxilla and especially the mandible are hypoplas-tic, showing accentuation of the antegonial notch anda steep mandibular angle, which gives the impressionthat the body of the mandible is bending in an inferiorand posterior direction (Fig. 29-4, C-1'). The ramus isespecially short, and the condyles are positioned poste-riorly and inferiorly. The maxillary sinuses may beunderdeveloped or absent.

ManagementThe mandibular abnormalities may be corrected byconventional orthognathic surgery and/or distractionosteogenesis to lengthen the ramus on the affectedside. Orthodontic intervention may correct or preventmalocclusion. The ear abnormalities may be repairedby plastic surgery or corrected with maxillofacial pros-

Differential DiagnosisOther disorders that may result in severe hypoplasiaof the entire mandible include condylar agenesis,



c

DFIG. 29-3 A and 8, Hemifacial microsomia, showing reduced size and malformation ofthe left ear and left side of the mandible. A, Clinical photograph of infant with hemifacialmicrosomia. 8, Three-dimensional CT image of the affected side shows the extent of thebony malformation. Note the complete absence of the TM) and coronoid process, as wellas auditory canal atresia. A panoramic image (C) and a posterior-anterior skull view (D) ofother cases showing lack of development of ramus, coronoid process, and condyle (arrows).(A and 8, Courtesy Dr. Arlene Rozzelle, Children's Hospital of Michigan, Detroit, Mich.)


645CHAPTER 29 DEVELOPMENTAL DISTURBANCES OF THE FACE AND JAWS

FIG. 29-4 A and B, Treacher Collins syndrome. Note the characteristic facies: down-ward-sloping palpebral fissures, colobomas of the outer third of the lower lids, depressedcheekbones, receding chin, little if any nasofrontal angle, and a nose that appears rela-tively large. C, Correlation of radiographic features with clinical features: short mandibu-lar rami, steep mandibular angle, and an anterior open bite. The zygomas are poorlyformed. D-F, Three-dimensional CT images of young child with Treacher Collins syndromeshow the extent of the bony abnormalities, including the bilateral auditory canal atresia,aplasia of the zygomatic arch, and hypoplasia of the mandibular ramus with characteristic"curved" shape of the mandibular body and pronounced antegonial notching. (F, CourtesyDr. Arlene Rozzelle, Children's Hospital of Michigan, Detroit, Mich.)



E FFIG. 29-4-cont'd

Hallermann-Streiff syndrome, Nager syndrome, andPierre Robin sequence, which can be a part of severalother genetic syndromes.

Clinical FeaturesAlthough the disease affects the entire skeleton, CCDprimarily affects the skull, clavicles, and dentition.Mfected individuals have been shown to be of shorterstature than unaffected relatives but not short enoughfor this to be considered a form of dwarfism. Theface appears small in contrast to the cranium becauseof hypoplasia of the maxilla, a brachycephalic skull(reduced anteroposterior dimension with increasedskull width), and the presence of frontal and parietalbossing. The paranasal sinuses may be underdeveloped.There is delayed closure of the cranial sutures, and thefontanels may remain patent years beyond ,the normaltime of closure. The bridge of the nose may ge broadand depressed, with hypertelorism (excessive distancebetween the eyes). The complete absence (aplasia) orreduced size (hypoplasia) of the clavicles allows exces-sive mobility of the shoulder girdle (Fig. 29-5, A and B).

The dental abnormalities produce most of the mor-bidity associated with cleidocranial dysplasia and areoften the reason for diagnosis in mildly affected indi-viduals. Characteristically, patients with this diseaseshow prolonged retention of the primary dentition anddelayed eruption of the permanent dentition. Extrac-tion of primary teeth does not adequately stimulateeruption of underlying permanent teeth. A study ofteeth from patients with cleidocranial dysplasiarevealed a paucity or complete absence of cellularcementum on both erupted an~ \lnerupted teeth.Often unerupted supernumerary teeth are present,and considerable crowding and disorganization of thedeveloping permanent dentition may occur. Recently

ManagementComprehensive treatment of patients with TreacherCollins syndrome is optimally provided by a multidisci-plinary Craniofacial Team. Growth of the facial bonesduring adolescence results in some cosmetic improve-ment. Surgical intervention, including bilateral distrac-tion osteogenesis of the mandible, may be used toimprove the osseous defects. Treatment of the externalear defects may involve plastic and reconstructivesurgery and/or maxillofacial prosthetics. Coordinatedorthodontics and orthognathic surgery are often usedto treat the malocclusion and improve function andesthetics.

SynonymCleidocranial dysostosis

DefinitionCleidocranial dysplasia (CCD) is an autosomal-

dominant malformation syndrome affecting bones and

teeth; it affects both sexes equally. Its prevalence is esti-

mated at 1 per 1 million. It can be inherited, or it may

arise as a result of sporadic mutation. CCD is caused by

a mutation in the RUNX2 gene on chromosome 6. It has

variable expressivity and almost complete penetrance.



A

c DFIG. 29-5 Cleidocranial dysplasia. A, Chest radiograph. Note the absence of clavicles.B, The result is excessive mobility of the shoulders. Note also the frontal bossing and under-developed maxilla. C, On a lateral radiograph, note the wormian (sutural) bones in theoccipital region (arrows) and the open fontanel (large arrow). D, A lateral skull film showinga lack of development of the parietal bones (arrows). (A, Courtesy Department of Radiol-

ogy, Baylor University Hospital, Dallas, Tex.)


648 RADIOGRAPHIC INTERPRETATION OF PATHOLOGYPART V

A patent (open) mandibular symphysis has beenreported in 3% of adults and 64% of children. Severalinvestigators have described the alveolar bone overly-ing unerupted teeth as being denser than usual, witha coarse trabecular pattern in the mandible. Thiscorrelates to the histologic findings of decreasedresorption and multiple reversal lines. It may accountfor the delayed eruption in teeth not mechanicallyobstructed by supernumerary and other uneruptedteeth.

Radiographic features associated with the teeth.Characteristic features include prolonged retentionof the primary dentition and multiple uneruptedpermanent and supernumerary teeth (Fig. 29-6). Thenumber of supernumerary teeth varies; as many as63 in one individual have been reported. Theunerupted teeth develop most commonly in the ante-rior maxilla and bicuspid~regions of the jaws. Manyresemble bicuspids, and these unerupted teeth maydevelop dentigerous cysts. The supernumerary teethdevelop, on average, 4 years later than the correspon-ding normal teeth. Because of this it has been pro-posed that the supernumerary teeth represent a thirddentition.

EFIG. 29-5-cont'd E, A posterior-anterior skull film. Thebrachycephaly results in a light-bulb-like shape to the sil-

houette of the skull and mandible.

Differential DiagnosisCleidocranial dysplasia may be identified by the familyhistory, excessive mobility of the shoulders, clinicalexamination of the skull, and pathognomonic radi-ographic findings of prolonged retention of theprimary teeth with multiple unerupted supernumeraryteeth. Other conditions associated with multipleunerupted and supernumerary teeth, such asGardner's syndrome and pycnodysostosi$, must beconsidered in the differential diagnosis.

the number of supernumerary teeth has been correlatedwith a reduction in skeletal height in these patients.

Radiographic FeaturesGeneral radiographic features. The characteristic skullfindings are brachycephaly, delayed or failed closure ofthe fontanels, open skull sutures, and multiplewormian bones (small, irregular bones in the suturesof the skull that are formed by secondary centers ofossification in the suture lines) (Fig. 29-5, G£). In themost severe cases, very little formation of the parietaland frontal bones may occur. Typically the clavicles areunderdeveloped to varying degrees, and in approxi-mately 10% of cases, they are completely absent. Otherbones also may be affected, including the long bones,vertebral column, pelvis, and bones of the hands andfeet.

ManagementIn cleidocranial dysplasia dental care should includethe removal of primary and supernumerary teeth toimprove the possibility of spontaneous eruption of thepermanent teeth. In order to aid the eruption ofnormal permanent teeth, the overlying bone should beremoved to expose the crown when half of the root isformed to aid their eruption. Autotransplantation ofteeth has been shown to be a successful strategy in treat-ing older patients. Ideally, patients should be identifiedearly, before 5 years of age, in order to take advantageof combined orthodontic/surgical treatment. Prostho-dontic rehabilitation with dental implants has beenused in some cases. Patients should be monitoredfor development of distal molars and cysts until lateadolescence.

Radiographic features of the jaws. In cleidocranialdysplasia the maxilla and paranasal sinuses character-istically are underdeveloped, resulting in maxillarymicrognathia. The mandible is usually normal in size.


649CHAPTER 29 DEVELOPMENTAL DISTURBANCES Of: THE FACE AND JAWS

Clinical FeaturesHemifacial hyperplasia begins at birth and usually con-tinues throughout the growing years. In some cases itmay not be recognized at birth but becomes moreapparent with growth. It often occurs with other abnor-malities, including mental deficiency, skin abnormali-ties, -compensatory scoliosis, genitourinary tractanomalies, and various neoplasms, including Wilms'tumor of the kidney, adrenocortical tumor, and hepa-toblastoma (Beckwith-Weidemann syndrome). Femalesand males are affected with approximately equal fre-quency. The dentition of affected individuals may showunilateral enlargement, accelerated development, and

SynonymsHemifacial hypertrophy, hemihyperplasia

DefinitionHemifacial hyperplasia is a condition in which half ofdie face-die maxilla alone, die maxilla widi diemandible, or half of the faces in concert widi oilierparts of die body-grows to unusual proportions. Thecause of diis condition is unknown. Some cases areassociated widi genetic diseases such as Beckwith-Weidemann syndrome.


RADIOGRAPHIC INTERPRETATION OF PATHOLOGY650 PART V

premature loss of primary teeth. The tongue and alve-olar bone enlarge on the involved side.

Differential DiagnosisThe differential diagnosis should cot;lsider hemifacialhypoplasia of the opposite side, arteriovenousaneurysms, hemangioma, and congenital lymph-edema. Also, severe condylar hyperplasia that mayinvolve half of the mandible should be considered (seeChapter 25). The presence of enlarged teeth togetherwith rapid eruption of the dentition suggests hemifacialhyperplasia. Cases limited to one side of the maxillamust be differentiated from monostotic fibrous dyspla-

Radiographic FeaturesRadiographic examination of the skulls of thesepatients reveals, on the affected side, enlargement ofthe bones, including the mandible (Fig. 29-7), maxilla,zygoma, and frontal and temporal bones. There havebeen a few cases reported involving only one side of themaxilla or one side of the mandible,

.

A

B CFIG. 29-7 Hemifacial hyperplasia, revealing enlargement of the right maxilla only.A, Panoramic radiograph shows accelerated dental development limited to the right maxillain a 5-year-old male. 8, A CT axial image using bone algorithm of the same patient, demon~strating enlargement of the maxillary cuspid and first bicuspid (arrows) as compared withthe contralateral side. C, Three-dimensional CT scan shows the subtle bony enlargement

of the right maxilla and the right cuspid.



sia and segmental odontomaxillary dysplasia, both ofwhich have characteristic changes in the radiographicappearance of the alveolar bone, not present in hemi-facial hyperplasia.

Differential DiagnosisOther conditions that must be dif~erentiated fromSOD include segmental hemifacial hyperplasia, mono-stotic fibrous dysplasia, and regional odontodysplasia.Hemifacial hyperplasia is not associated with coarsevertically oriented trabeculae in the bone; mono-stotic fibrous dysplasia is not typically associated withmissing teeth and unlike SOD, will continue to showdisproportionate growth of the affected side; andregional

odontodysplasia typically is associated withghost teeth and is not associated with expansionand alteration in trabecular pattern in the alveolarbone.

ManagementThere have not been a significant number of cases ofhemifacial hyperplasia reported with long-term follow-up to make definitive recommendations for treatment.Although most cases are isolated, a child with suspectedhemifacial hyperplasia should be referred to a medicalgeneticist for diagnosis and early detection of one ofseveral genetic syndromes that can be associated withthis condition.

Lingual Salivary GlandDepressionSynonymsLingual mandibular bone depression, developmentalsalivary gland defect, Stafne defect, Stafne bone cyst,static bone cavity, and latent bone cyst

SynonymHemimaxillofacial dysplasia

DefinitionSegmental odontomaxillary dysplasia (SOD) is a devel-opmental abnormality of unknown etiology that affectsthe posterior alveolar process of one side of onemaxilla, including the teeth and attached gingiva.

DefinitionLingual mandibular bone depressions represent agroup of concavities in the lingual surface of themandible, where the depression is lined with an intactouter cortex. Historically they were referred to aspseudocysts because they resemble cysts radiographi-cally, but they are not true cysts because no epithe-lial lining is present. The most common location iswithin the submandibular gland fossa and often closeto the inferior border of the mandible. This lingualposterior variant (LP) of these depressions was firstdescribed by Stafne in 1942. This well-defineq deepdepression is thought to result from or be associatedwith growth of the salivary gland adjacent to thelingual surface of the mandible. Similar defects havealso been described in the anterior region near theapical region of the bicuspids, associated with the sub-lingual glands (lingual anterior variant, or lA), andvery rarely on the medial surface of the ascendingramus, associated with the parotid gland (medialramus variant, or MR). In LP developmental bonedefects investigated surgically, an aberrant lobe of thesubm_andibular gland has been described to extendinto the bony depression; however, CT imaging ofsome of these defects reveals fat tissue and no evidenceof gland. The etiology remains unknown, but thecondition is a developmental anomaly that has beendocumented to develop in patients as old as 30 yearsand as young as 11 years. These defects may continueto slowly grow in size.

Clinical FeaturesThe abnormality is always unilateral and results inenlargement of the alveolar process, gingiva, and teeth.Frequently teeth are missing (most commonly the bicus-pids), and some of the teeth that remain are unerupted.Unilateral hypertrichosis and mild facial enlargementhave been reported in a few cases. Most cases aredetected in childhood because a parent notices the lackof tooth eruption or mild facial asymmetry, or thedentist notices missing premolars radiographically.

Radiographic FeaturesThe density of the maxillary alveolar process isincreased, with a greater number of thick trabeculaethat appear to be aligned in a vertical orientation (Fig.29-8). The roots of the deciduous teeth are larger thanon the unaffected side and usually are splayed in shape.The crowns of the deciduous teeth and sometimes thepermanent teeth are enlarged. Enlargement of pulpchambers and irregular resorption of the roots ofdeciduous teeth also may be seen. The maxillary sinusdoes not pneumatize the alveolar process and thusappears smaller than on the contralateral side. Thereis often delayed eruption of the first and secondpermanent molars.



8 cFIG. 29-8 A, A panoramic view of segmental odontomaxillary dysplasia. Note the largeleft maxillary deciduous molars compared with the right side and the lack of formation ofthe bicuspids, delayed eruption of the first molar, and the dense bone pattern of the leftmaxillary alveolar process. Band C, A second case demonstrating the coarse trabecularpattern of the right maxillary alveolar process and delayed eruption of the maxillary rightfirst bicuspid and molars.

gland fossa. Rare LA examples are located in the apicalregion of the mandibular premolars or cuspids and arerelated to the sublingual gland fossa, above the mylo-hyoid muscle. The margins of the radiolucent defectare well defined by a dense sclerotic radiopaque marginof variable width, which is usually thicker on the supe-rior aspect. This appearance is the result of the x rayspassing tangentially through the relatively thick walls ofthe depression. This cortical outline is often less distinctin the LA variant. The LP defect may involve the infe-rior border of the mandible. Computed tomography(CT) images reportedly reveal tissue, with the samedensity as fat within the defect (Fig. 29-10), or in somecases, there is continuity of the tissue within the defectwith the adjacent salivary gland.

Clinical FeaturesAlthough lingual mandibular bone depressions appearto be relatively rare, with an incidence of LP of about0.10%-0.48%, it is likely that many go unreported. LAincidence is even less, at 0.009%. These concavities areasymptomatic and almost impossible to palpate; gener-ally they are discovered only incidentally during radi-ographic examination of the area. In a recent review ofa large number of cases, males predominated femalesat 6.1: 1 with a peak incidence in the fifth and sixthdecades.

Radiographic FeaturesA lingual mandibular bone depression is a well-definedround, ovoid, or occasionally, lobulated radiolucencythat ranges in diameter from 1 to 3cm (Fig. 29-9). TheLP defect is located below the inferior alveolar nervecanal and anterior to the angle of the mandible, in theregion of the antegonial notch and submandibular

Differential DiagnosisThe appearance and location of the radiographic imageof this developmental bone defect are characteristic and



B

A

cFIG. 29-9 A, Lingual mandibular bone depressions of the posterior variant usually areseen as sharply defined radiolucencies beneath the mandibular canal in the region of thesubmandibular gland fossa. These defects can erode the inferior border of the mandible.8, An unusual variant with a superior position above the inferior alveolar canal. C, Ananterior variant within the sublingual gland fossa.


RADIOGRAPHIC INTERPRETATION OF PATHOLOGY654 PART V

BA

CFIG. 29-10 CT scans of lingual mandibular bone depressions, posterior variant. A andB are axial bone and soft tissue windows of the same case. Note the well-defined defectextending from the medial surface of the mandible and the corresponding soft tissueimage, which shows radiolucent tissue within the defect that has the density equivalent offat tissue (arrow). (, A three-dimensional, reformatted CT image revealing a defect extend-ing from the medial surface of the mandible.

Focal Osteoporotic Bone Marroweasily identified. Lingual mandibular bone depressionscan be readily differentiated from odontogenic lesionssuch as cysts because the epicenter of odontogeniclesions is located above the inferior alveolar canal.However, when the defect is related to the sublingualgland and appears above the canal, odontogenic lesionsshould be considered in the differential diagnosis.

SynonymMarrow space

DefinitionFocal osteoporotic bone marrow is a radiologic termindicating the presence of radiolucent defects withinthe cancellous portion of the jaws. Histologic examina-tion- reveals normal areas of hematopoietic or fattymarrow. The etiology is unknown but has been pos-tulated to be (1) bone marrow hyperplasia, (2) persist-ent embryologic marrow rel;nnants, or (3) sites ofabnormal healing following extraction'-, trauma, or localinflammation. This entity is a variation of normal

anatomy.

ManagementRecognition of the lesion should preclude any treat-ment or surgical exploration or the need for advancedimaging such as CT. The defect may increase in sizewith time. There are rare reports of salivary gland neo-plasms developing in the soft tissue within the defect.Destruction of the well-defined cortex of the defect mayindicate the presence of a neoplasm.



The immediate surrounding bone is normal, withoutany sign of a bone reaction (Fig. 29-11).

Clinical FeaturesFocal osteoporotic bone marrow defects are usuallyclinically asymptomatic and are commonly an inciden-tal radiographic finding. These marrow spaces aremore common in middle-aged women.

Differential DiagnosisA small simple bone cyst may have a similar appearancebecause there is usually no bone reaction at the periph-ery of a simple bone cyst. When the osteoporotic bonemarrow occurs in the furcation region or at the apex ofa tooth, the differential diagnosis includes the presence"of an inflammatory lesion. If the area is normal bonemarrow, the lamina dura should be intact. Very earlyinflammatory lesions that have not yet stimulated avisible osteoblastic response may appear similar.

Radiographic FeaturesA common site for focal osteoporotic bone marrow isthe mandibular molar-premolar region. Other sitesinclude the maxillary tuberosity region, mandibularretromolar area. edentulous locations, occasionally thefurcation .region of mandibular molars, and rarely thearea near the apex of teeth. The radiographic appear-ance of focal osteoporotic bone marrow space is quitevariable. The internal aspect is radiolucent because ofthe presence of fewer trabeculae in comparison withthe surrounding bone. The periphery may be ill-defined and blending or may appear to be corticated.

ManagementNo treatment is required for the osteoporotic bonemarrow space. Prior radiographs of the region shouldalways be obtained if available. ~en doubt exists about

B

DFIG. 29-11 A-C, Focal osteoporotic bone marrow defect, seen as a radiolucency(arrow). A few internal trabeculae may be present, and the periphery varies from welldefined to ill defined. D, An example located in the furcation of a mandibular first molar.Note that the periodontal ligament space and lamina dura are intact.



the true nature of the radiolucency, a longitudinal studywith films at 3-month intervals may be prescribed. Themarrow space should not increase in size.

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CHAPTER 29 DEVELOPMENTAL DISTURBANCES OF THE FACE AND JAWS 657

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CAROL ANNE MURDOCH-KINCH · dentition. Management The craniofacial features of Crouzon syndrome worsen over time because of the abnormal craniofacial growth. Early diagnosis permits