Volume 3, Issue 2 US $6.00

Editor:

Allan G. Farman, BDS, PhD(odont.), DSc (odont.),Diplomate of theAmerican Board of Oraland MaxillofacialRadiology, Professor ofRadiology and ImagingSciences, Department ofSurgical and HospitalDentistry, The University ofLouisville School ofDentistry, Louisville, KY.

Featured Article:

Panoramic radiologicappraisal of anomalies ofdentition: Chapter #2

In The Recent Literature:

Impacted canines

Space assessment

Age determination

Hypodontia

Apical root resorption

Third molar eruptionassessment

FAQs:

Infection control

Reading films

By Dr. Allan G. Farman

Panoramic radiologic appraisal ofanomalies of dentition: Chapter #2

The previous chapterhiglighted the sequential nature ofdevelopmental anomalies of thedentition in general missing teethin particular. This chapter providesdiscussion supernumerary teethand anomalies in tooth size.

Supernumeraries:Supernumeraries are present whenthere is a greater than normalcomplement of teeth or toothfollicles. This condition is alsotermed hyperodontia. The fre-quency of supernumerary teeth ina normal population is around 3 %[1]. Most supernumeraries are foundin the anterior maxilla (mesiodens)or occur as para- and distomolarsin that jaw (see Fig. 1). These arefollowed in frequency bypremolars in both jaws (Fig. 2, 3).Pre-, post- or para-dentitionsupernumeraries are possibledepending on the timing ofdevelopment of the supernumer-ary teeth in relation to that of theregular teeth. Most supernumerar-ies are rudimentary or conical inshape; however, some are regularin shape and are then termedsupplemental teeth. Supernumer-ary premolars are frequentlysupplemental. Complications fromsupernumerary teeth includeimpactions and displacement ordelayed eruption of regular teeth.Most individual supernumeraryteeth are sporadic in occurance;however, multiple supernumerariescan occur in association withcleidocranial dysplasia orGardner’s syndrome. Multiplesupernumeraries should be differ-

entiated from compound odonto-mas. Compound odontomas areencapsulated discrete hamar-tomatous collections of den-ticles.

Recognition of supernumeraryteeth is essential to determiningappropriate treatment [2]. Diag-nosis and assessment of themesiodens is critical in avoidingcomplications such asimpedence in eruption of themaxillary central incisors, cystformation, and dilaceration of thepermanent incisors. Collectingdata for diagnostic criteria,utilizing diagnostic radiographs,and determining when to refer toa specialist are important steps inthe treatment of mesiodens [2].Early diagnosis and timely surgicalintervention can reduce oreliminate the need for orthodon-tic treatment and reduce compli-cations to the regular dentition insuch cases. As a good rule ofthumb, if a permanent tooth iserupted to half its crown heightand the contralateral equivalenttooth in the same arch is not seenclinically, a radiograph should bemade to investigate the cause.

In a series of 10 cases ofsupernumerary premolars treatedin Barcelona only one casealtered the normal eruption of theregular premolars; two evidencedfollicular cyst development [3].

This is consistent with thesupernumerary premolars com-monly being post-dentition inonset and being impeded fromeruption by the regular teeth.Panoramic radiography is animportant step toward the identi-

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“ Cleidocranial dysplasia is an autosomally dominant conditioncharacterized by defective ossification of cranial bonesand clavicles.”

fication, localization and surgicalremoval of these supernumeraryteeth [4].

(a) Cleidocranial dysplasia:Cleidocranial dysplasia is anautosomally dominant conditioncharacterized by defectiveossification of cranial bones andclavicles. It is associated withmultiple supernumerary teeth,especially anterior to the firstpermanent molars, retainedprimary teeth and uneruptedpermanent teeth (Fig. 4). There isalso delayed fontanelle closure,and hypolasia or aplasia of theclavicles [5].

McNamara et al. (1999)reported the effectiveness ofdental panoramic radiography inidentifying features pathogno-monic for cleidocranial dysplasia[6]. In addition to the establisheddental complications of failure oferuption of the permanentdentition and multiple supernu-merary teeth, morphologicalabnormalities of the maxilla andmandible, particularly in theascending ramus and coronoidprocess are present. While thereoften are numerous supernumer-ary teeth present in cleidocranialdysplasia this might not beapparent clinically. Failures intooth eruption often results inapparent hypodontia. It is oftennecessary to fabricateoverdentures for theprosthodontic treatment of suchpatients.

Dentigerous cysts may formaround the crowns of uneruptedregular and supernumerary teethweakening the structure of thejaw and predisposing it to patho-logic fracture. Dental panoramicradiography is a valuable adjunctin confirming the diagnosis of

Fig. 1: Unerupted mesiodens(arrowed on panoramic radiograph)is causing displacement of theadjacent regular central incisors.Uncommonly (photograph) there isroom for the mesiodens to eruptand “function”.

Fig. 2: Post-dentition supplementalsupernumerary premolars are illustratedin the panoramic radiograph. Theclinical photograph shows dentalmalocclusion occurring in a patienthaving three such supplemental teeththat have erupted. The dried jawspecimen is of an ancient Indian jawmore than 1000 year old (Mississippian)showing an erupted supplementalpremolar tooth.

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cleidocranial dysplasia and insubsequently checking fordentigerous cyst formation.

(b) Gardner’s syndrome:Gardner’s syndrome (famialadenomatosis coli; intestinalpolyposis type II ) is character-ized by the occurrence ofmultiple impacted supernumer-ary teeth, osteomas of the longbones, skull and jaws, multiplepolyposis of the large intestinesand multiple epidermoid ordermoid cysts Significantly, theintestinal polyps are premalig-nant. Detection of osteomas inthe jaws and multiple supernu-merary teeth (Fig. 5) on pan-oramic radiology may lead tothe early determination of thesyndrome and preventivemanagement of a potentiallyfatal malignancy [7]. In amatched study 82 % of patientshaving this syndrome showedosteomatous changes com-pared to 10 % of controls. Super-numerary teeth, compoundodontomas and impacted teethwere found in 30 % of patientshaving Gardner’s syndromecompared to 4 % of controls.

Anomalies in Tooth Size(a) Macrodontia

Macrodontia involves a tooth orteeth being larger than normal insize with proportional enlarge-ment of pulp chamber, crownand root (Fig 6). This conditionmay be general or localized.General true macrodontia canbe associated with pituitarygiantism. Unilateral relativemacrodontia can occur inhemifacial hypertrophy. Macro-dontia is often sporadic, but canalso be a feature of Ekman-Westborg-Julin syndrome [8, 9].There is usually a normal

Fig. 3: Multiple unerupted supernumeraryteeth in the mandible that are notinterfering with the regular dentition. Insuch cases a syndrome such as cleidoc-ranial dysplasia should be ruled out.

Fig. 4: Cleidocranial dysplasia isassociated with multiple supernu-merary teeth (panoramic radio-graph). Affected patients oftenhave hypoplastic or absentclavicles and have the flexibility tobring their shoulders close togetherin the midline (e.g. photograph).

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complement of teeth. Macro-dontia needs to be differenti-ated from connation (gemina-tion or fusion) and concres-cence. In germination there isdivision of a tooth with anattempt to make an additionaltooth. In fusion there is combina-tion of two or more teeth with areduction in number. For fusion,this number count presupposesthat the combination does notinvolve a supernumerary tooth orteeth. Concrescence is thejoining of adjacent teeththrough cementum.

Early detection of macro-dontia is of importance fororthodontic planning of spaceand cosmetic intervention.Certainly if space is not avail-able for eruption of all of theteeth due to macrodontia,impaction or malocclusion islikely to ensue. Panoramicradiology can help in earlydiagnosis. Caution needs to beapplied; however, as the crownof a tooth that is lingually orpalatally displaced will appearmagnified horizontally on stan-dard panoramic views. Moreovercare needs to be made toensure the patient was posi-tioned symmetrically in thecephalostat. Rotation or lateraldisplacement of the head duringpanoramic radiology can causeone side of the jaws and teethto be minified, while the otherside is magnified.

(b) MicrodontiaMicrodontia implies the abnor-mal smallness of a single ormultiple teeth. This is mostcommonly an isolated anomalysuch as a peg lateral or diminu-tive third molar tooth (Fig. 7). The

Fig. 5: Gardner’ssyndrome: multipleosteomas arepresent in both jawsand there are alsoretained primaryteeth and multipleimpacted perma-nent teeth. Suchpatients are alsoprone to developintestinal cancer.

Fig. 6: Sporadic macro-dontia results in adisproportionately largetooth crown in compari-son with the contralat-eral counterpart tooth(radiograph). Thephotograph illustrates a case ofmacrodont lateral incisior in which thetooth was similar in size to a maxillarycentral incisor tooth.

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“ Microdontia implies the abnormal smallness of a single or multipleteeth. This is most commonly an isolated anomaly such as a peglateral or diminutive third molar tooth.”

diminutive tooth tends to besomewhat conical in shape.Such teeth need to be differ-entiated from rudimentarysupernumerary teeth, andabnormally shaped teeth dueto ectodermal dysplasia orradiation in childhood. Earlydetection of microdontia canbe effected by use of pan-oramic radiology for evalua-tion of growth and develop-ment.

Baccetti (1998) examinedpatterns of associationamong five types of dentalanomalies (aplasia of secondpremolars, small size ofmaxillary lateral incisors,infraocclusion of primarymolars, ectopic eruption offirst molars, and palataldisplacement of maxillarycanines) in an untreatedorthodontic population, aged7-14 years [10]. The prevalenceof associated tooth anoma-lies in five groups of 100subjects each and character-ized by the constant presence

of one primarily diagnosed dentalanomaly was compared to theprevalence for the examineddental anomalies in a controlgroup of 1,000 subjects, derivingfrom a common initial sample of4,850 subjects. Significant recipro-cal associations (p < 0.008) werefound among the dental anoma-lies studied. The statisticallydemonstrated existence ofassociations among differenttooth anomalies was felt to beclinically relevant, since thediagnosis of a dental anomolymay indicate an increasedchance for later developmentaltooth and eruption disturbances.Panoramic Radiology: animportant adjunct in the assess-ment of dental anomalies

This and the previous chapterreviewed anomalies in the numberand size of teeth. These condi-tions are of importance forpatient esthetics – and conse-quently may affect perceptionsof self-worth. Early detection ofdental anomalies isof importancefor planning timely orthodontic

References1. Yanagida I, Mori S. Statistical studies on

numerical anomalies of teeth in childrenusing orthopantomograms-congenitalhypodontia. Osaka Daigaku ShigakuZasshi 1990;35:580-593.

2. Atwan SM, Turner D, Khalid A. Earlyintervention to remove mesiodens andavoid orthodontic therapy. Gen Dent2000;48:166-169.

3. Valmaseda-Castellon E, Berini-Aytes L,Gay-Escoda C. Supernumerarypremolars. Report of 10 cases. Bull GroupInt Rech Sci Stomatol Odontol2001;43:19-25.

4. Yeung KH, Lau YW, Lee KH. Mandibularsupernumerary premolars: orthodonticand surgical considerations. Prim DentCare 1997;4:115-117.

5. Farman AG, Nortjé CJ, Wood R. Oral andMaxillofacial Diagnostic Imaging. 1993;Mosby: St Louis.

6. McNamara CM, O’Riordan BC, Blake M,Sandy JR. Cleidocranial dysplasia:radiological appearances on dentalpanoramic radiography.Dentomaxillofac Radiol 1999;28:89-97.

7. Wolf J, Jarvinen HJ, Hietanen J. Gardner’sdento-maxillary stigmas in patients withfamilial adenomatosis coli. Br J OralMaxillofac Surg 1986;24:410-416.

8. Ekman-Westborg B, Julin P. Multipleanomalies in dental morphology:macrodontia, multituberculism, centralcusps, and pulp invaginations. Oral SurgOral Med Oral Pathol 1974;38:217-222.

9. Yoda T, Ishii Y, Honma Y, Sakai E, EnomotoS. Multiple macrodonts with odontomain a mother and son – a variant ofEkman-Westborg-Julin syndrome. OralSurg Oral Med Oral Pathol Oral RadiolEndod 1998;85:301-303.

10. Baccetti T. A clinical and statisticalstudy of etiologic aspects related toassociated tooth anomalies in number,size, and position. Minerva Stomatol1998;47:655-663.

Fig. 7: Bilateral microdont mandibularsecond permanent molar teeth. In such asituation preservation of the third molarsshould be a consideration.

intervention to assure optimalfunction dental occlusion andstomatognathic function. Thepanoramic radiograph is animportant adjunct in the assess-ment of normal growth anddevelopment. In the future,Panoramic Imaging News willcover anomalies in tooth mor-phology and dental structure.

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“ Panoramic radiographs can be used to assess eruption patternsand space availability for posterior teeth.”

In The Recent Literature:Impacted canines: Panoramicradiography combined with alateral cephalometric image isuseful in treatment planningimpacted maxillary canines.Stivaros N, Mandall NA. Radio-graphic factors affecting themanagement of impacted upperpermanent canines. J Orthod2000 Jun;27(2):169-73. [From theOrthodontic Department, Univer-sity Dental Hospital, Manchester,UK.]

The investigators used a retro-spective, cross-sectional designto evaluate radiographic factorsinfluencing the orthodontists’decision whether to expose orremove an impacted upperpermanent canine. Panoramicand lateral cephalometric radio-graphic records of patientsreferred between 1994 and 1998to the Orthodontic Departmentat Manchester University DentalHospital having impacted upperpermanent canines (n = 44) wereevaluated. Canine positionmeasurements made from thepanoramic radiograph wereangulation to the midline, verticalheight, antero-posterior positionof the root, overlap of the adja-cent incisor, and presence of rootresorption of adjacent incisor(s).The labio-palatal position of theimpacted canine was assessedfrom the lateral skull radiograph.Whether the impacted caninehad been exposed andorthodontically aligned or re-moved was also recorded.Stepwise logistic regressionanalysis showed that the labio-palatal position of the crown

influenced the treatment deci-sion, with palatally positionedimpacted canines more likely tobe surgically exposed and thosein the line of the arch, or labiallysituated, removed (p < 0.05).Additionally, as the canine angu-lation to the midline increased,the canine was more likely to beremoved (p < 0.05). The orthodon-tists’ decision to expose orremove an impacted upperpermanent canine, based onradiographic information, seemsto be primarily guided by twofactors: labio-palatal crownposition and angulation to themidline. These can be readilyassessed using a combination ofpanoramic radiography and alateral cephalometric image.

Space assessment: Panoramicradiographs can be used toassess eruption patterns andspace availability for posteriorteeth.Tsai HH. Eruption process of thesecond molar. ASDC J DentChild 2000 Jul;67(4):275-81. [Fromthe Department of Pedodontics,School of Dentistry, China Medi-cal College, Taichung, Taiwan,Republic of China.]

This study observed the eruptionprocess of maxillary and man-dibular second molars by evaluat-ing 238 panoramic radiographs.The developmental of the secondmolars was divided into fourstages: completion of crowncalcified = stage 1; initial rootformation = stage 2; initial forma-tion of the radicular bifurcation =stage 3; and root length equal to

crown height = stage 4. Themesiodistal crown width ofthe first and second molars,axial inclination and eruptionrate of these teeth, and thespace available for theiremergence was measured ateach stage. Statistical analy-sis was performed to assesschanges in development.Mandibular second molarsbegan to erupt at stage 3and maxillary second molarsat stage 2. The axial inclina-tion of the mandibular sec-ond molars was essentiallyunchanged from stages 1 to 4but maxillary second molarsuprighted gradually fromstage 1 to 4. The availablespace increased significantlyfrom stage 1 to 2 in both jaws.It is suggested that the spaceavailable for emergence ofthe second molar is preparedbefore stage 2, and then thetooth begins to erupt. For themaxillary second molars,there was a further increase inthe available space afterstage 3. A negative correla-tion was determined betweenthe mesiodistal crown widthof the mandibular secondmolar and the available jawspace at stage 2. A positivecorrelation was seen be-tween the mesiodistal crownwidth of maxillary secondmolars and the available jawspace at stage 3.

Age determination: Standardcriteria have been devel-oped using panoramicradiographs for the assess-

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ment of biologic age inSwedish children and adoles-cents.Nystrom M, Aine L, Peck L,Haavikko K, Kataja M. Dentalmaturity in Finns and theproblem of missing teeth.Acta Odontol Scand 2000Apr;58(2):49-56. [From theDepartment of Pedodonticsand Orthodontics, Universityof Helsinki, Finland.]

Development of teeth wasstudied from 2483 dentalpanoramic radiographs of1651 healthy patients rangingin age from 2 to 25 years.Dental maturity was assessedusing a method based ondevelopmental stages ofseven left mandibular teeth.Sex-specific tables weredeveloped of maturity as afunction of chronological ageand of ages as a function ofmaturity scores. Percentilegraphs for visual evaluationsof dental maturity in childrenand adolescents were alsodeveloped. Since maturityscales do not tolerate anymissing data, the authorsdeveloped linear regressionmodels for predicting theformation stages of each ofthe seven mandibular teeth. Itwas easiest to predict theformation stage of the man-dibular first molars (correct in87% within the study material)and most difficult to predictthe formation stage of sec-ond molars and secondpremolars (correct in 69% and70%, respectively.

Apical root resorption: Pan-oramic radiographs made beforeand following orthodontic treat-ment has been used to assessapical root resorption.McNab S, Battistutta D, TaverneA, Symons AL. External apicalroot resorption following orth-odontic treatment. Angle Orthod2000 Jun;70(3):227-32. [From theFaculty of Health, QueenslandUniversity of Technology,Brisbane, Australia.]

The association of appliancetype and tooth extraction withthe incidence of external apicalroot resorption of posterior teethfollowing orthodontic treatmentwas investigated using pre- andpost-treatment panoramicradiographs. The study comprised97 patients. A 4-level ordinal scalewas used to rate external apicalroot resorption. The analysis wasmutually adjusted for the effectsof age at the start of treatment,pre-treatment overbite andoverjet, use of headgear, toothextraction, and type of appli-ance. The incidence of suchresorption was positively associ-ated with tooth position (p < .001),appliance type (p = .038), andextractions (p = .001). The inci-dence of resorption was 2.3 timeshigher for Begg appliance treat-ment compared with edgewise,and it was 3.7 times higher whereextractions had been performedthan when they were not.

Hypodontia: Panoramic radio-graphs showed that hypodontiais more frequent in patientshaving hemifacial microsomia

than in matched individualswithout this condition.Maruko E, Hayes C, Evans CA,Padwa B, Mulliken JB. Hypodontiain hemifacial microsomia. CleftPalate Craniofac J 2001Jan;38(1):15-9. [From the Depart-ment of Oral Health Policy andEpidemiology, Harvard School ofDental Medicine, Boston, USA.]

This study described the patternsof missing teeth in patientshaving hemifacial microsomia(HFM) and compared the preva-lence of missing teeth in subjectswith HFM with a group of unaf-fected subjects. Missing teethwere determined by evaluation ofpanoramic radiographs. Recordsof 125 patients with HFM wereavailable from the CraniofacialCenter at Boston’s Children’sHospital. Seventy-six met inclusioncriteria for radiographic analysisof hypodontia. Fifty-two patientsmet inclusion criteria for compar-ing the prevalence of hypodontiawith a group of patients from theDepartment of Orthodontics atHarvard School of Dental Medi-cine. A Fisher’s exact test wasconducted to test the hypothesisthat HFM patients have a greaterprevalence of missing teeth thanindividuals without the anomaly. Achi2 test for trend was conductedto determine whether hypodontiawas more prevalent with increas-ing severity of the mandibulardeformity in HFM. Hypodontia wasmore prevalent among HFMpatients (26.9%) versus the com-parison group (p < .0001). Addi-tionally, the degree of hypodontiawas correlated with the grade of

©2003 Panoramic Corporation (4-03)

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mandibular hypoplasia (p = .024).Hypodontia was found to be moreprevalent in patients with HFMthan in comparison subjects.

Third molar eruption assessment:Sequential panoramic radio-graphs can be used to evaluateeruption of third molars followingextraction of second molar teeth.Orton-Gibbs S, Crow V, Orton HS.Eruption of third permanentmolars after the extraction ofsecond permanent molars. Part1: Assessment of third molarposition and size. Am J OrthodDentofacial Orthop 2001Mar;119(3):226-38. [From theSt Helier Hospital, Surrey, UK.]

The eruptive path of third molarsafter extraction of second molarswas examined in 63 patients.

Panoramic radiographs from thestart and the end of activetreatment and three or moreyears after treatment wereassessed. Study models wereused to compare the size of thesecond and third molar teeth andto assess the final position of thethird molars following eruption. Allthird molars erupted; none be-came impacted. During eruption,maxillary third molar crownsuprighted and maintained theirangulation as they came intoocclusion. Mandibular third molarcrowns continued to uprightsignificantly mesiodistally afteractive treatment, with spaceclosure being the result of hori-zontal translation rather thanmesial tipping. Further uprightingoccurred once occlusion wasestablished although few be-

came as upright as thesecond molars they replaced.Mandibular third molar rootswere frequently curveddistally, thus the third molarcrown position was invariablybetter than the overall toothangulation would suggest by16.5o on average. Modelanalysis (Richardsons’ scoringsystem) showed 96 % ofmandibular and 99 % ofmaxillary third molars eruptedinto an acceptable position.The mesiodistal size of thirdmolars was suitable to re-place second molars. Onaverage, mandibular thirdmolars were 0.55 mm largerand maxillary third molarswere 0.70 mm smaller thansecond molars.

Q: What infection controlprecautions or practices shouldbe applied to the use of aPanoramic Corporation PC-1000X-ray machine?

A: Universal precautions asrecommended by the CDC, OSHA,ADA and OSAP should be applied.Wearing of exam gloves isrecommended. The hand grips,chin rest, forehead support, templesupports, and any surface thatmay potentially come in contactwith the patient, either directly orsecondary from the operator,should be disinfected with a hardsurface disinfectant such asBIREXse or should be draped. Thebite-guide used to position thepatient is designed to be

Frequently Asked Questions:disposable and is notautoclavable. Discard and replaceafter each use. When using thecephalometric attachment,disposable rubber covers should beplaced over the ear rods. Surfacedisinfectants should be used onany direct or secondary contactsurfaces.

Q: Is there a method for readingpanoramic radiograms to assurea thorough review of everythingbeing shown?

A: One approach was suggested byDr. Allan Farman, our editor, in theinitial Panoramic Imaging NewsVol 1. #1. “I approach the radiographroughly in the numerical sequenceshown, namely starting with thebony landmarks from the midline of

the upper jaw and nasal cavity,then working back in the maxillaand zygomatic complex on eachside. The soft tissue shadows of thetongue and soft palate areincorporated at this stage. This isfollowed by evaluation of thecervical spine and associatedstructure. I then evaluate thecontents of the mandible startingfrom the midline and thenprogressing posteriorly on eachside. Any examination would beincomplete without a thoroughevaluation of the soft tissuesanterior to the spine and inferior tothe mandible. The last part of theevaluation should be the area ofchief complaint and the dentalarches. You can sequence yourevaluation in many ways; however,it is very important to develop aconsistent approach that ensuresthat all diagnostic information inthe radiograph is indeed read.”

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