Volume 3, Issue 3 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 ofthe dentition: Chapter #3 —Tooth morphology

In The Recent Literature:Film selection

Third molars

Supernumerary teeth

Jaw cysts

Dental age assessment

Stylohyoid ossification

Learning Objectives:Gain understanding ofdetection of developmentalanomalies of the dentition.

Be able to identifyradiographically thefollowing anomalies:dilaceration, taurodontism,enamel pearl, connation,concresence, talon cusp,dens invaginatus, densevaginatus, andsupernumerary roots.

By Dr. Allan G. Farman

Panoramic radiologic appraisal of anomalies ofthe dentition: Chapter #3 — Tooth morphology

The previous chapters re-viewed the sequential nature ofdevelopmental anomalies of thedentition in general and anoma-lies in number and size of teeth inparticular. This chapter continuesthe theme of developmentalanomalies of the dentition withprimary focus on tooth morphol-ogy. While coronal anomalies inmorphology are most frequentlydetected without the use ofradiographs, anomalies in rootmorphology are usually notapparent without the assistanceof radiology. These conditions canbe frequently encountered in theaverage private general practiceand do affect dental treatmentplanning. For this reason, lessattention will be made to anoma-lies in morphology of toothcrowns, especially for conditionsaffecting the anterior teeth.

DilacerationDilaceration is an angulation

in the root or crown [1,2]. Thedetermined prevalence of dilac-

eration depends largely on thesubjective assessment of what is“normal” and what is “excessive”angulation. All tooth roots arecurved to some degree, so theterm dilaceration is reserved forinstances of excess or abnormalroot curvature that may compli-cate endodontic or exodontictreatment (Fig. 1). The configura-tion of the root of a prospectiveabutment tooth has a significantinfluence on its potential load-bearing capacity; hence, thisabnormality may also affect thestability and longevity of anabutment [2]. Dilaceration is mostcommon in the permanentdentition. It is thought to resultfrom prior local infection, traumaor impaction; however, the pre-cise cause has not been eluci-dated. Clinically, the tooth oftenappears structurally and position-ally normal so the condition ismost likely to be discoveredradiographically. It should be rememberedthat conventional radiographs,including panoramic images, areessentially two-dimensional

Fig. 1: Bilateral dilacerations of mandibular canines was only evident on radiography. Thiswould need to be considered should orthodontic, endodontic, exodontic or fixed pros-thodontic treatment involve these teeth in the future.

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“ Taurodontism is usually bilateral and symmetric in distribution,although involvement of an isolated tooth is not rare.”

shadows of three-dimensionalobjects. While mesio-distaldilacerations are relatively easyto determine, bucco-lingualangulations require a little moreattention to detail. Withdilacerations in a buccal-lingualdirection, the radiographicappearance is that of a “bull’seye” root (Fig. 2) caused by aview down the root axis showingthe innermost pulp canal sur-rounded by tooth structure [1].Missing these forms ofdilacerations has been postu-lated to be a significant factor inthe failure of endodontic treat-ment due to miscalculation of theactual root apex [3].

TaurodontismTaurodontism is an inherited

morphologic anomaly ofmultirooted teeth caused byfailure of invagination of theHertwig epithelial root sheath [1].Taurodontism is usually bilateraland symmetric in distribution,although involvement of anisolated tooth is not rare. Clinicalexamination of involved teethfails to reveal any abnormality.Radiologically, affected molar orpremolar teeth appear rectangu-lar with an absence of the normalcervical constriction of the root.There is an increased occlusal-apical dimension to the pulpchamber with diminished apicalroot length (Fig. 3 and 4).

Taurodontism has beenreported in association with anumber of conditions [4-8]; and isfrequently seen in patients havingexcessive numbers of X chromo-somes [9,10]. However, it can occurin otherwise normal patients,perhaps as an atavistic memoryof prehistoric ancestors. As will befound in most standard texts, the

condition has been reported inNeanderthal remains found invarious sites in Europe [11-12].

Neanderthals are known toexhibit enlarged pulp chambers inpostcanine teeth (taurodontism);however, Bailey (2002) found thatthey are not only unique in theirpattern of dental trait frequen-

cies, but also present a highrate of a mid-trigonid crest inlower molars [12]. Taurodontismis, however, relatively com-mon in modern man, particu-larly in Africa [13,14]. Toure et al(2000) reported a frequencyof 48 % in 150 consecutiveSenagalese dental patients

Fig. 2:Bucco-lingualdilacerationsneed carefulradiographicscrutiny for the“bull’s eye” signshown in thepre-extractionradiographicdetail (A).Radiographs ofthe extractedtooth are

shown in a similar orientation to thepre-extraction radiograph (B) androtated through 90o (C).

Fig. 3: Taurodontism: Themandibular first molar teethare missing due to extrac-tion in this adolescentpatient. The fully formedmandibular second molarteeth show the typical features of taurodontism;namely an extended pulp chamber and veryshort apical roots.

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therapy has been documented insuch teeth [18]. It has also beenreported that taurodonts showincreased susceptibility to apicalroot resorption during orthodontictreatment [19]. Panoramic radiogra-phy has been found to be a reli-able means of assessingtaurodontism [20].

Enamel PearlThe most common site for

extradental enamel pearls is at thecementoenamel junction of multi-rooted teeth [1]. They are mostcommonly mesial or distal onmaxillary teeth and buccal orlingual on mandibular teeth (Fig. 5).Enamel pearls most often occursingly and may be composedexclusively of enamel. They vary insize from microscopic to a fewmillimeters. Radiologically, they aredepicted as dense, smooth radio-pacities overlying any portion ofthe crown or root of an otherwiseunaffected tooth. The majorradiologic differential diagnosis isprojection geometry causingoverlap of root contours in multi-rooted teeth. In the primary denti-tion, radiographic interpretationand detection of the enamel pearlmay be complicated by thesuperimposition of the developingpermanent tooth [21]. In a study ofdental patients, the frequencyreported for enamel pearls onmolar teeth was 1.6% [22]. It hasbeen reported that enamel pearlscan predispose to local periodon-tal disease and should thereforebe removed [23]; however, as theycan contain dentin and pulp,caution is advised.

ConnationConnated or “double” teeth

includes both fusion and germina-tion. In the case of fusion of adja-

aged 15-19 years with 18.8% offirst and second molars beingaffected [13]. By way ofcomparison, the prevalenceof taurodontism in Jordanianswas determined to be 8%,and 11% in a Saudi population[15,16]. MacDonald-Jankowskiand Li found taurodontism in

56% of female and 36% of maleChinese adolescents who theystudied [17]. Hence, in diversepopulations, taur-odontism canbe considered simply a variationof normal.

What are the implications oftaurodontism for dental treat-ment? Successful endodontic

Fig. 4: Taurodontismin the mixeddentition showingthat this conditioncan affect bothpermanent (A) andprimary (B)dentitions.

Fig. 5: Enamel pearl shown (arrow) on thedetail of a panoramic radiograph. Theclinical appearance of enamel pearl onan extracted molar tooth and theradiograph of this extracted tooth arealso illustrated.

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cent teeth, there should be areduction in the total number solong as one of the fused teeth isnot a supernumerary. In the caseof germination, there may be theclinical appearance of an addedtooth. The result, in either case, isa tooth with an unusually broadcrown that may show groovingbetween elements that areconnected by enamel, dentin,pulp or a combination of thesetissues. Connation is compara-tively rare depending on thepopulation, being found in from0.08% of Saudi children to 1.5% ofpatients examined in westernIndia [24-27]. Unless there is failurein eruption, connation is oftenobvious upon clinical inspection(Fig. 6). Clinical problems relatingto fusion may be unacceptableappearance, misalignment ofteeth and often periodontalconditions [28].

ConcresenceConcresence is the joining of

adjacent teeth through cementalunion of their roots [1]. It can eitheroccur during development or beacquired. The cardinal radiologicsign of concrescence is closeproximity of adjacent teeth withno detectable intervening peri-odontal ligament space shadow.When developmental, it might beassociated with failed eruption ofone or more teeth. When ac-quired, it may be associated withgross hypercementosis.

Talon CuspA tooth with a talon cusp

generally appears T-shaped (Fig.7A) when viewed from the incisaledge [1] with most additionalcusps being lingual and only rarereports of facial talons [29,30]. Thiscondition is clinically obvious and

Fig. 7A: Talon cusp; 7B: Densinvaginatus; 7C: Clinicalappearance of densinvaginatus; 7D: Radiographicdetail of dens evaginatus –note how the pulp extendsinto the central tubercle.

Connation

Fig. 6: The upper clinical pictureshows a case of connation(germination) of a maxillary centralincisor complicated by periodontaldisease and lateral periodontalabscess. The lower image sequenceis of a connation specimen where amesiodens is fused to two primarycentral incisors.

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“ Dens invaginatus (dens in dente) refers to invagination of toothstructure, most commonly affecting the cingular surface of amaxillary incisor tooth.”

only requires radiographicanalysis to determine whetherpulpal extensions may bepresent within the “talon.” Thisis best performed usingperiapical radiography.

Dens InvaginatusDens invaginatus (dens in

dente) refers to invaginationof tooth structure, mostcommonly affecting thecingular surface of a maxillaryincisor tooth (Fig. 7B). This isoften, but not invariably,suspected clinically. The lesionneeds radiographic appraisal,principally using an intraoralradiograph. If no entrance tothe invagination can bedetected clinically and thereare no signs of pulp pathosis,then no treatment is requiredother than fissure sealing ofthe invagination [31,32]. Indeep invaginations, it is likelythat root-canal treatmentmay be required. Extensiveenamel invaginations may beapparent on panoramic

radiographs, as will complicationsequels such as an apical ab-scess, cyst or granuloma.

Dens EvaginatusDens evaginatus (Fig. 7C,D) is

uncommon in most populations,but occurs in roughly 2% ofAsians and Native Americans[33]. In this dental anomaly, anextra cusp or tubercle protrudesfrom the occlusal surface ofposterior teeth, or occasionally,from the lingual surface ofanterior teeth [34]. Complica-tions can arise if the tubercle isworn, ground, or fractured off,resulting in pulpal exposure andpossible loss of vitality of thetooth. Radiographs are importantto assess the shape of the pulpchamber should dental restor-ative procedures be required.Orthodontists, consideringpremolar extraction cases,should include extraction of theanomalous premolars instead ofthe normal ones. Radiographicassessment is important in suchinstances.

Supernumerary RootsThe normal number of roots

or root canals can show varia-tions from the expected, makingradiographic evaluation espe-cially relevant when planningendodontic therapy orexodontias [35,36]. Mandibularmolars generally have two roots;however, the detail in Figure 8Ashows a mandibular molar withthree roots. Similarly, the onlypremolar to consistently havetwo separate roots is the maxil-lary first premolar tooth. Figure8B shows a mandibular premolarwith a supernumerary root.

Panoramic Radiology: animportant adjunct in the as-sessment of dental morphology

Panoramic radiography is animportant adjunct to clinicalinspection for detection ofanomalies in dental morphology.Such findings are important inselecting teeth for extractionwhen needed for orthodonticreasons. Cholitgul andDrummond (2000) studied thepanoramic radiographs of 1,608children and adolescents fromNew Zealand and found toothabnormalities in 21% of thesestudies. They concluded thatpanoramic radiography isvaluable for detecting or con-firming dental abnormalities, andsupported recommendations forthe use of panoramic radiogra-phy to aid in the assessment ofdental development [37]. Pan-oramic radiographs are alsoimportant in planning dentalcoronal restorations and endo-dontic therapy. In future issues,Panoramic Imaging News willcover anomalies in tooth struc-ture and dental eruption pat-terns.

Fig. 8A: Supernumerary root (arrow) onmandibular molar tooth; 8B: Supernumeraryroot (arrow) on mandibular premolar tooth.

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“ Supplemental supernumerary premolar teeth can becomeradiographically apparent at a stage much later than thatfor the regular dentition.”

In The RecentLiterature:

References1. Farman AG, Nortjé CJ, Wood RE. Oral

and Maxillofacial Diagnostic Imaging.St. Louis: Mosby 1993;pp.65-104.

2. Celik E, Aydinlik E. Effect of adilacerated root on stress distribution tothe tooth and supporting tissues. JProsthet Dent 1991;65:771-777.

3. Chohayeb AA. Dilaceration of perma-nent upper lateral incisors: frequency,direction, and endodontic treatmentimplications. Oral Surg Oral Med OralPathol 1983;55:519-520.

4. Seow WK, Needleman HL, Holm IA. Effectof familial hypophosphatemic rickets ondental development: a controlled,longitudinal study. Pediatr Dent 199517:346-350.

5. Kaste SC, Hopkins KP, Jones D, Crom D,Greenwald CA, Santana VM.Dental abnormalities in children treatedfor acute lymphoblastic leukemia.Leukemia 1997;11:792-796.

6. Rajic Z, Mestrovic SR.Taurodontism inDown’s syndrome. Coll Antropol 1998;22Suppl:63-67

7. Melnick M, Shields ED, El-Kafrawy AH.Tricho-dento-osseous syndrome: ascanning electron microscopic analysis.Clin Genet 1977;12:17-27.

8. Aldred MJ, Savarirayan R, Lamande SR,Crawford PJ. Clinical and radiographicfeatures of a family with autosomaldominant amelogenesis imperfecta withtaurodontism. Oral Dis 2002;8:62-68.

9. Varrela J, Alvesalo L, MayhallJ.Taurodontism in 45,X females. J DentRes 1990 ; 69:494-495.

10. Hillebrand U, Mohr C, Plewa G.Taurodontism in patients with sexchromosome anomalies. Dtsch Z MundKiefer Gesichtschir 1990;14:187-189.

11. Lebel S, Trinkaus E. Middle Pleistocenehuman remains from the Bau del’Aubesier: J Hum Evol 2002;43:659-685.

12. Bailey SE. A closer look at Neanderthalpostcanine dental morphology: themandibular dentition. Anat Rec2002;269:148-156,

13. Toure B, Kane AW, Sarr M, Wone MM, Fall F.Prevalence of taurodontism at the levelof the molar in the black Senegalesepopulation 15 to 19 years of age.Odontostomatol Trop 2000;23:36-39.

14. Constant DA, Grine FE. A review oftaurodontism with new data onindigenous southern African populations.Arch Oral Biol 2001;46:1021-1029.

15. Darwazeh AM, Hamasha AA, Pillai KPrevalence of taurodontism in Jordaniandental patients. Dentomaxillofac Radiol1998;27:163-165.

16. Ruprecht A, Batniji S, el-Neweihi E. Theincidence of taurodontism in dentalpatients. Oral Surg Oral Med Oral Pathol1987;63:743-747.

17. MacDonald-Jankowski DS, Li TT.Taurodontism in a young adult Chinesepopulation. Dentomaxillofac Radiol1993;22:140-144.

18. Hayashi Y. Endodontic treatment intaurodontism. J Endod 1994;20:357-358.

19. Kjaer I. Morphological characteristics ofdentitions developing excessive root

resorption during orthodontictreatment.Eur J Orthod 1995;17:25-34.

20. Tulensalo T, Ranta R, Kataja M. Reliabilityin estimating taurodontism of perma-nent molars from orthopantomograms.Community Dent Oral Epidemiol1989;17:258-262.

21. Kupietzky A, Rozenfarb N. Enamel pearlsin the primary dentition: report of twocases. ASDC J Dent Child 1993;60:63-66.

22. Darwazeh A, Hamasha AA. Radiographicevidence of enamel pearls in Jordaniandental patients. Oral Surg Oral Med OralPathol Oral Radiol Endod 2000;89:255-258.

23. Goldstein AR. Enamel pearls as contrib-uting factor in periodontal breakdown. JAm Dent Assoc 1979;99:210-211.

24. Salem G. Prevalence of selected dentalanomalies in Saudi children from Gizanregion. Community Dent Oral Epidemiol1989;17:162-163.

25. Backman B, Wahlin BY. Variations innumber and morphology of permanentteeth in 7-year-old Swedish children. Int JPaediatr Dent 2001;11:11-17.

26. Knezevic A, Travan S, Tarle Z, Sutalo J,Jankovic B, Ciglar I. Double tooth. CollAntropol 2002;26:667-672.

27. Tasa GL, Lukacs JR. The prevalence andexpression of primary double teeth inwestern India. ASDC J Dent Child2001;68:196-200.

28. Mader CL, Fusion of teeth. J Am DentAssoc 1979;98:62-64.

29. Nadkarni UM, Munshi A, Damle SG.Unusual presentation of talon cusp: twocase reports. Int J Paediatr Dent2002;12:332-335.

30. McNamara T, Haeussler AM, Keane J.Facial talon cusps. Int J Paediatr Dent1997;7:259-262.

31. Goncalves A, Goncalves M, Oliveira DP,Goncalves N. Dens invaginatus type III:report of a case and 10-year radio-graphic follow-up. Int Endod J2002;35:873-879.

32. Gound TG. Dens invaginatus—a pathwayto pulpal pathology: a literature review.Pract Periodontics Aesthet Dent1997;9:585-594.

33. McCulloch KJ, Mills CM, Greenfeld RS,Coil JM. Dens evaginatus from anorthodontic perspective: report ofseveral clinical cases and review of theliterature.Am J Orthod DentofacialOrthop 1997;112:670-675.

34. Stecker S, DiAngelis AJ. Densevaginatus: a diagnostic and treatmentchallenge. J Am Dent Assoc2002;133:190-193.

35. Kannan SK, Suganya, Santharam HSupernumerary roots.Indian J Dent Res2002;13:116-119.

36. Morrow JW, Hylin DL. Supernumeraryrooted primary central incisors: report ofseven cases. ASDC J Dent Child1993;60:337-338.

37. Cholitgul W, Drummond BK. Jaw andtooth abnormalities detected onpanoramic radiographs in New Zealandchildren aged 10-15 years. N Z Dent J2000;96:10-13.

Film selection: Both KodakEktavision and AgfaOrthoLux did well in stan-dard sensitometric tests andin the perceived clarity ofimage features.Wakoh M, Nishikawa K,Kobayashi N, Farman AG,Kuroyanagi K. Sensitometricproperties of Agfa DentusOrthoLux, Agfa Dentus ST8G,and Kodak Ektavisionpanoramic radiographicfilm. Oral Surg Oral MedOral Pathol Oral RadiolEndod 2001 Feb;91(2):244-51.[From the Department ofOral and MaxillofacialRadiology Tokyo DentalClinic, Japan and theUniversity of Louisville, USA.]

This study compares thepanoramic imaging qualitiesof Kodak Ektavision, AgfaOrthoLux panoramic radio-graphic film, and Agfa ST8Gfilms in combination withKodak versus Agfa intensify-ing screens. The densityresponse and resolution ofpanoramic radiographic film/intensifying screen combina-tions was evaluated bymeans of Hurter and Driffieldcurves, modulation transferfunction (MTF), and noise-equivalent number of quanta(NEQ). Image clarity ofselected anatomical struc-tures was also rated. The ISOspeed for the Agfa OrthoLuxfilm/screen combinationswas the fastest, and theKodak Ektavision system wasthe slowest. The averagegradient for the Agfa ST8Gsystem was relatively steepin comparison with those forthe other film/screen combi-nations indicating a narrower

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recording latitude. The MTFsfor the Kodak Ektavision film(a measure of spatial resolu-tion) were higher than thosefor the Agfa films, irrespectiveof the screen combinationused. The NEQ for the AgfaST8G film/screen combina-tions was lower than that forthe other film/screen combi-nations tested. The NEQ forthe Kodak Ektavision film/screen combinations was wellwithin the high-frequencyrange; whereas Agfa OrthoLuxcombined with either theKodak Ektavision imagingscreen or the Kodak LanexRegular imaging screenproduced a NEQ similar tothat of the Kodak Ektavisionfilm/screen combinations inthe low-frequency range.Agfa OrthoLux was perceivedto provide clearer images ofthe selected anatomicaldetails than Agfa ST8G, andthe Agfa OrthoLux/AgfaOrtho Regular 400 combina-tion was not significantlydifferent from the KodakEktavision/Kodak LanexRegular combination in termsof perceived image quality.Agfa OrthoLux is an improve-ment over Agfa ST8G in filmspeed, spatial resolution,granularity, and perceiveddiagnostic image quality. TheAgfa OrthoLux/Agfa OrthoRegular 400 combination;however, did not exceed theKodak Ektavision film/KodakEktavision imaging screencombination in terms ofresolution, granularity, andperceived image quality.

Third molars that appearimpacted at age 18 y canoften erupt into normalocclusion by age 26 y.Kruger E, Thomson WM,Konthasinghe P. Third molaroutcomes from age 18 to 26:findings from a population-

based New Zealand longitudinalstudy. Oral Surg Oral Med OralPathol Oral Radiol Endod2001;92:150-155. [From the De-partment of Oral Health, Schoolof Dentistry, University of Otago,Dunedin, New Zealand.]

This study evaluated the pres-ence and impaction status ofthird molars in persons at age 18years, as well as the observedchanges in their clinical statusbetween ages 18 and 26 years.

This prospective cohort studywas performed on 821 individualsfor whom panoramic radiographswere taken at age 18 years. Foreach tooth, its radiographicimpaction status at age 18 yearswas compared with the clinicalstatus by age 26 years. Of the2857 third molars assessed atage 18 years, 93 % were followedclinically to age 26 years. Ap-proximately 55 % of the teeththat were not impacted by age18 had erupted by 26 years. Ofthe teeth that were impacted byage 18, 34 % had fully erupted byage 26, 31 % had been extractedand 13 % remained unerupted. Ofthe maxillary teeth that werecategorized as “impacted” atage 18 years, 36 % had fullyerupted by age 26, whereas 26 %of the mandibular teeth haddone so (P <.01). Fewer mandibu-lar teeth than maxillary teethremained unerupted by the timethe patient was 26 years old (27% and 41 %, respectively; P <.01),but there was no significantdifference between the jaws inthe proportion of impactedteeth at age 18 years that hadbeen extracted by age 26 years(both 30 %). For mesioangularlyimpacted third molars, 39 % ofmaxillary teeth and 20 % ofmandibular teeth had fullyerupted by age 26, whereasalmost one-third of each hadbeen extracted. Of thedistoangularly impacted thirdmolars, 20 % of the maxillary

teeth and one-third of the man-dibular teeth had erupted by age26, with 22.6% of the maxillaryteeth and 32 % of the mandibularteeth having been extracted. It isconcluded that other than hori-zontally impacted third molars, asubstantial proportion of otherimpaction types do erupt fully,and radiographically apparentimpaction in late adolescenceshould not be sufficient groundsfor their prophylactic removal inthe absence of other clinicalindications.

Supernumerary teeth: Sequentialpanoramic radiographs evi-denced the late development ofa post-dentition supplementalsupernumerary tooth.Gibson N. A late developingmandibular premolar supernu-merary tooth. Aust Dent J 2001Mar;46(1):51-2. [From the TorbayHospital, Torquay, UK.]

Supplemental supernumerarypremolar teeth can becomeradiographically apparent at astage much later than that for theregular dentition. The case of apatient who developed a man-dibular premolar supernumerarytooth between the age of 11 and20 years is reported. Evidence forthe late development of thesupernumerary tooth came fromconsecutive panoramic radio-graphs.

Jaw cysts: Panoramic imageswere used to compare the radio-graphic features of the mandibu-lar odontogenic keratocysts andthe dentigerous cysts associatedwith third molars.Tsukamoto G, Sasaki A, AkiyamaT, Ishikawa T, Kishimoto K,Nishiyama A, Matsumura T. Aradiologic analysis of dentiger-ous cysts and odontogenickeratocysts associated with amandibular third molar. Oral SurgOral Med Oral Pathol Oral RadiolEndod 2001 Jun;91(6):743-47. [From

©2003 Panoramic Corporation (7-03)

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the Department of Oral andMaxillofacial Surgery II,Okayama University DentalSchool, Okayama, Japan.]

The objective was to discriminateradiographically between denti-gerous cysts and odontogenickeratocysts associated with amandibular third molar. Panoramicradiographs were studied forcases of dentigerous cysts (44patients, 45 cysts) and odontoge-nic keratocysts (15 patients, 16cysts). All cysts were associatedwith a mandibular third molar. Thepanoramic images were analyzedwith reference to the patients’ages and symptoms. The meanage of patients in whom odonto-genic keratocysts were detectedwas less than that of patientshaving dentigerous cysts. Themean size of odontogenickeratocysts was larger than thatof dentigerous cysts. The meandistance from the second to thethird molar for dentigerous cystswas greater than that for odonto-genic keratocysts. While therewas a significant correlationbetween the lesion size and thedistance between the secondand third molars in the dentiger-ous cyst versus the odontogenickeratocyst, the patients’ ages didnot significantly correlate withthese features: Odontogenickeratocysts tended to grow morerapidly than dentigerous cysts,but did not cause as much toothdisplacement. No evidence wasfound for either cyst type todevelop gradually from the timeof initiation of the dental follicleor the dental lamina. They ratherarose randomly at various stages.

Dental age assessment: Pan-oramic radiography provides anexcellent means of assessing the

dental age of patients; however,there is a need to developseparate assessment standardsfor different population groups.Davidson LE, Rodd HD. Interrela-tionship between dental ageand chronological age in Somalichildren. Community Dent Health2001;18:27-30. [From theDepartment of Child DentalHealth, School of Clinical Den-tistry, University of Sheffield, UK].

This cross-sectional study com-pared dental age with chrono-logical age in Somali childrenunder 16 years of age and age-and gender-matched whiteCaucasian children, all resident inSheffield, England. The samplegroup comprised 162 subjects: 84Somali and Caucasian boys(mean age 10.6 y) and 78 Somaliand Caucasian girls (mean age11.2 y). The dental age was as-sessed for each subject, usingtheir existing panoramic radio-graphs. Comparisons of thedifference between dental ageand chronological age weremade for each gender and bothethnic groups. Independentsample tests were employed forstatistical analysis. The level ofsignificance was set at p < 0.05.The mean difference betweendental age and chronologicalage was found to be 1.0 years forSomali boys, 0.2 years for Cauca-sian boys, 1.2 years for Somali girls,and 0.5 years for Caucasian girls.The difference between dentaland chronological age wassignificantly greater in Somalisubjects than in Caucasianchildren. The authors concludethat Somali children are moredentally advanced than theirCaucasian peers. This findingunderlines the need for popula-tion-specific dental development

standards for accurate dentalage assessment.

Stylohyoid ossification: Ossifica-tion within the stylohyoid chain isdemonstrable on panoramicradiography. Such ossificationincreases with increased patientage.Krennmair G, Lenglinger F,Lugmayr H. Variants of ossifica-tion of the stylohyoid chain. RofoFortschr Geb Rontgenstr NeuenBildgeb Verfahr 2001Mar;173(3):200-4. [From the Clinicfor Oral and MaxillofacialSurgery, University of Vienna,Austria.].

Panoramic radiographs of 380patients (including 718 radio-graphs clearly depicting theregions of the stylohyoid chains),were subdivided into 4 agegroups (= 20 y, 21-40 y, 41-60 y, > 60y), and were reviewed andexamined for the incidence,length and location(s) of ossifica-tions in the stylohyoid chains.Elongation of the styloid processand/or ossification of the stylohy-oid ligament was found in 221(30.8%) of the reviewed stylohy-oid chains. With increasing age,there was an increase in theprevalence and length of stylohy-oid ossifications (p < 0.01). Asignificant linear correlationbetween the length of thestylohyoid ossifications and agewas only found in the young agegroup (= 20 y; p < 0.01). In this agegroup, there was also a predomi-nance of isolated locations ofossification in the superior stylo-hyoid segment. With increasingpatient age, the presence ofossifications in the middle andinferior stylohyoid segments andcombinations of ossified variabili-ties were prominent. The authorsconclude that stylohyoid ossifica-tion shows age-related differ-ences in incidence, length andtopography.

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