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Home , Dens evaginatus, Dens invaginatus, Dilaceration, Enamel pearl, Supernumerary root, Talon cusp

Volume 3, Issue 3 US $6.00

Editor: Panoramic radiologic appraisal of anomalies of Allan G. Farman, BDS, PhD (odont.), DSc (odont.), the dentition: Chapter #3 — morphology Diplomate of the eration depends largely on the American Board of Oral By Dr. Allan G. Farman and Maxillofacial subjective assessment of what is Radiology, Professor of The previous chapters re- “normal” and what is “excessive” Radiology and Imaging viewed the sequential nature of angulation. All tooth roots are Sciences, Department of developmental anomalies of the curved to some degree, so the Surgical and Hospital dentition in general and anoma- term is reserved for , The University of lies in number and size of teeth in instances of excess or abnormal Louisville School of particular. This chapter continues root curvature that may compli- Dentistry, Louisville, KY. the theme of developmental cate endodontic or exodontic anomalies of the dentition with treatment (Fig. 1). The configura- Featured Article: primary focus on tooth morphol- tion of the root of a prospective Panoramic radiologic ogy. While coronal anomalies in abutment tooth has a significant appraisal of anomalies of the dentition: Chapter #3 — morphology are most frequently influence on its potential load- Tooth morphology detected without the use of bearing capacity; hence, this radiographs, anomalies in root abnormality may also affect the In The Recent Literature: morphology are usually not stability and longevity of an Film selection apparent without the assistance abutment [2]. Dilaceration is most of radiology. These conditions can common in the permanent Third molars be frequently encountered in the dentition. It is thought to result Supernumerary teeth average private general practice from prior local infection, trauma and do affect dental treatment or impaction; however, the pre- Jaw cysts planning. For this reason, less cise cause has not been eluci- Dental age assessment attention will be made to anoma- dated. Clinically, the tooth often lies in morphology of tooth appears structurally and position- Stylohyoid ossification crowns, especially for conditions ally normal so the condition is most likely to be discovered Learning Objectives: affecting the anterior teeth. radiographically. Gain understanding of detection of developmental Dilaceration It should be remembered anomalies of the dentition. Dilaceration is an angulation that conventional radiographs, in the root or [1,2]. The including panoramic images, are Be able to identify determined prevalence of dilac- essentially two-dimensional radiographically the following anomalies: dilaceration, , , connation, concresence, talon , , , and supernumerary roots.

Fig. 1: Bilateral dilacerations of mandibular canines was only evident on radiography. This would need to be considered should orthodontic, endodontic, exodontic or fixed pros- thodontic treatment involve these teeth in the future. “ Taurodontism is usually bilateral and symmetric in distribution, although involvement of an isolated tooth is not rare.”

shadows of three-dimensional Fig. 2: objects. While mesio-distal Bucco-lingual dilacerations are relatively easy dilacerations to determine, bucco-lingual need careful radiographic angulations require a little more scrutiny for the attention to detail. With “bull’s eye” sign dilacerations in a buccal-lingual shown in the direction, the radiographic pre-extraction appearance is that of a “bull’s radiographic detail (A). eye” root (Fig. 2) caused by a Radiographs of view down the root axis showing the extracted the innermost pulp canal sur- tooth are rounded by tooth structure [1]. shown in a similar orientation to the Missing these forms of pre-extraction radiograph (B) and rotated through 90o (C). dilacerations has been postu- lated to be a significant factor in the failure of endodontic treat- ment due to miscalculation of the actual root apex [3].

Taurodontism Taurodontism is an inherited morphologic anomaly of multirooted teeth caused by failure of invagination of the Hertwig epithelial root sheath [1]. Taurodontism is usually bilateral and symmetric in distribution, although involvement of an isolated tooth is not rare. Clinical examination of involved teeth fails to reveal any abnormality. Radiologically, affected or Fig. 3: Taurodontism: The teeth appear rectangu- mandibular first molar teeth lar with an absence of the normal are missing due to extrac- tion in this adolescent cervical constriction of the root. patient. The fully formed There is an increased occlusal- mandibular second molar apical dimension to the pulp teeth show the typical features of taurodontism; chamber with diminished apical namely an extended pulp chamber and very root length (Fig. 3 and 4). short apical roots. Taurodontism has been reported in association with a condition has been reported in cies, but also present a high number of conditions [4-8]; and is Neanderthal remains found in rate of a mid-trigonid crest in frequently seen in patients having various sites in Europe [11-12]. lower molars [12]. Taurodontism excessive numbers of X chromo- Neanderthals are known to is, however, relatively com- somes [9,10]. However, it can occur exhibit enlarged pulp chambers in mon in modern man, particu- in otherwise normal patients, postcanine teeth (taurodontism); larly in Africa [13,14]. Toure et al perhaps as an atavistic memory however, Bailey (2002) found that (2000) reported a frequency of prehistoric ancestors. As will be they are not only unique in their of 48 % in 150 consecutive found in most standard texts, the pattern of dental trait frequen- Senagalese dental patients

2 therapy has been documented in such teeth [18]. It has also been reported that taurodonts show increased susceptibility to apical root resorption during orthodontic treatment [19]. Panoramic radiogra- phy has been found to be a reli- able means of assessing taurodontism [20].

Enamel Pearl The most common site for extradental enamel pearls is at the of multi- Fig. 4: Taurodontism rooted teeth [1]. They are most in the mixed commonly mesial or distal on dentition showing maxillary teeth and buccal or that this condition lingual on mandibular teeth (Fig. 5). can affect both Enamel pearls most often occur permanent (A) and singly and may be composed primary (B) exclusively of enamel. They vary in dentitions. size from microscopic to a few millimeters. Radiologically, they are depicted as dense, smooth radio- pacities overlying any portion of the crown or root of an otherwise unaffected tooth. The major radiologic differential diagnosis is projection geometry causing overlap of root contours in multi- rooted teeth. In the primary denti- tion, radiographic interpretation and detection of the enamel pearl may be complicated by the superimposition of the developing Enamel pearl shown (arrow) on the Fig. 5: permanent tooth [21]. In a study of detail of a panoramic radiograph. The clinical appearance of enamel pearl on dental patients, the frequency an extracted molar tooth and the reported for enamel pearls on radiograph of this extracted tooth are molar teeth was 1.6% [22]. It has also illustrated. been reported that enamel pearls can predispose to local periodon- aged 15-19 years with 18.8% of 56% of female and 36% of male tal disease and should therefore first and second molars being Chinese adolescents who they be removed [23]; however, as they affected [13]. By way of studied [17]. Hence, in diverse can contain and pulp, comparison, the prevalence populations, taur-odontism can caution is advised. of taurodontism in Jordanians be considered simply a variation was determined to be 8%, of normal. Connation and 11% in a Saudi population What are the implications of Connated or “double” teeth [15,16]. MacDonald-Jankowski taurodontism for dental treat- includes both fusion and germina- and Li found taurodontism in ment? Successful endodontic tion. In the case of fusion of adja-

3 cent teeth, there should be a Fig. 6: The upper clinical picture reduction in the total number so shows a case of connation (germination) of a maxillary central long as one of the fused teeth is complicated by periodontal not a supernumerary. In the case disease and lateral periodontal of germination, there may be the abscess. The lower image sequence clinical appearance of an added is of a connation specimen where a tooth. The result, in either case, is mesiodens is fused to two primary central . a tooth with an unusually broad crown that may show grooving between elements that are connected by enamel, dentin, pulp or a combination of these tissues. Connation is compara- tively rare depending on the Connation population, being found in from 0.08% of Saudi children to 1.5% of patients examined in western India [24-27]. Unless there is failure in eruption, connation is often obvious upon clinical inspection (Fig. 6). Clinical problems relating to fusion may be unacceptable appearance, misalignment of teeth and often periodontal conditions [28].

Concresence Concresence is the joining of adjacent teeth through cemental union of their roots [1]. It can either Fig. 7A: ; 7B: Dens occur during development or be invaginatus; 7C: Clinical acquired. The cardinal radiologic appearance of dens sign of is close invaginatus; 7D: Radiographic proximity of adjacent teeth with detail of dens evaginatus – no detectable intervening peri- note how the pulp extends odontal ligament space shadow. into the central tubercle. When developmental, it might be associated with failed eruption of one or more teeth. When ac- quired, it may be associated with gross hypercementosis.

Talon Cusp A tooth with a talon cusp generally appears T-shaped (Fig. 7A) when viewed from the incisal edge [1] with most additional cusps being lingual and only rare reports of facial talons [29,30]. This condition is clinically obvious and

4 “ Dens invaginatus (dens in dente) refers to invagination of tooth structure, most commonly affecting the cingular surface of a maxillary incisor tooth.”

Supernumerary Roots The normal number of roots or root canals can show varia- tions from the expected, making radiographic evaluation espe- cially relevant when planning endodontic therapy or exodontias [35,36]. Mandibular molars generally have two roots; however, the detail in Figure 8A shows a mandibular molar with three roots. Similarly, the only premolar to consistently have two separate roots is the maxil- lary first premolar tooth. Figure 8B shows a mandibular premolar Fig. 8A: (arrow) on with a supernumerary root. mandibular molar tooth; 8B: Supernumerary root (arrow) on mandibular premolar tooth. Panoramic Radiology: an important adjunct in the as- only requires radiographic radiographs, as will complication sessment of dental morphology analysis to determine whether sequels such as an apical ab- Panoramic radiography is an pulpal extensions may be scess, cyst or granuloma. important adjunct to clinical present within the “talon.” This inspection for detection of is best performed using Dens Evaginatus anomalies in dental morphology. periapical radiography. Dens evaginatus (Fig. 7C,D) is Such findings are important in uncommon in most populations, selecting teeth for extraction Dens Invaginatus but occurs in roughly 2% of when needed for orthodontic Dens invaginatus (dens in Asians and Native Americans reasons. Cholitgul and dente) refers to invagination [33]. In this dental anomaly, an Drummond (2000) studied the of tooth structure, most extra cusp or tubercle protrudes panoramic radiographs of 1,608 commonly affecting the from the occlusal surface of children and adolescents from cingular surface of a maxillary posterior teeth, or occasionally, New Zealand and found tooth incisor tooth (Fig. 7B). This is from the lingual surface of abnormalities in 21% of these often, but not invariably, anterior teeth [34]. Complica- studies. They concluded that suspected clinically. The lesion tions can arise if the tubercle is panoramic radiography is needs radiographic appraisal, worn, ground, or fractured off, valuable for detecting or con- principally using an intraoral resulting in pulpal exposure and firming dental abnormalities, and radiograph. If no entrance to possible loss of vitality of the supported recommendations for the invagination can be tooth. Radiographs are important the use of panoramic radiogra- detected clinically and there to assess the shape of the pulp phy to aid in the assessment of are no signs of pulp pathosis, chamber should dental restor- dental development [37]. Pan- then no treatment is required ative procedures be required. oramic radiographs are also other than fissure sealing of Orthodontists, considering important in planning dental the invagination [31,32]. In premolar extraction cases, coronal restorations and endo- deep invaginations, it is likely should include extraction of the dontic therapy. In future issues, that root-canal treatment anomalous instead of Panoramic Imaging News will may be required. Extensive the normal ones. Radiographic cover anomalies in tooth struc- enamel invaginations may be assessment is important in such ture and dental eruption pat- apparent on panoramic instances. terns.

5 “ Supplemental supernumerary premolar teeth can become radiographically apparent at a stage much later than that for the regular dentition.”

References resorption during orthodontic 1. Farman AG, Nortjé CJ, Wood RE. Oral treatment.Eur J Orthod 1995;17:25-34. and Maxillofacial Diagnostic Imaging. 20. Tulensalo T, Ranta R, Kataja M. Reliability In The Recent St. Louis: Mosby 1993;pp.65-104. in estimating taurodontism of perma- 2. Celik E, Aydinlik E. Effect of a nent molars from orthopantomograms. dilacerated root on stress distribution to Community Dent Oral Epidemiol Literature: 1989;17:258-262. the tooth and supporting tissues. J Film selection: Both Kodak Prosthet Dent 1991;65:771-777. 21. Kupietzky A, Rozenfarb N. Enamel pearls 3. Chohayeb AA. Dilaceration of perma- in the primary dentition: report of two Ektavision and Agfa nent upper lateral incisors: frequency, cases. ASDC J Dent Child 1993;60:63-66. OrthoLux did well in stan- direction, and endodontic treatment 22. Darwazeh A, Hamasha AA. Radiographic dard sensitometric tests and implications. Oral Surg Oral Med Oral evidence of enamel pearls in Jordanian Pathol 1983;55:519-520. dental patients. Oral Surg Oral Med Oral in the perceived clarity of 4. Seow WK, Needleman HL, Holm IA. Effect Pathol Oral Radiol Endod 2000;89:255- image features. of familial hypophosphatemic rickets on 258. Wakoh M, Nishikawa K, dental development: a controlled, 23. Goldstein AR. Enamel pearls as contrib- longitudinal study. Pediatr Dent 1995 uting factor in periodontal breakdown. J Kobayashi N, Farman AG, 17:346-350. Am Dent Assoc 1979;99:210-211. Kuroyanagi K. Sensitometric 5. Kaste SC, Hopkins KP, Jones D, Crom D, 24. Salem G. Prevalence of selected dental properties of Agfa Dentus Greenwald CA, Santana VM. anomalies in Saudi children from Gizan Dental abnormalities in children treated region. Community Dent Oral Epidemiol OrthoLux, Agfa Dentus ST8G, for acute lymphoblastic leukemia. 1989;17:162-163. and Kodak Ektavision Leukemia 1997;11:792-796. 25. Backman B, Wahlin BY. Variations in panoramic radiographic number and morphology of permanent 6. Rajic Z, Mestrovic SR.Taurodontism in film. Oral Surg Oral Med Down’s syndrome. Coll Antropol 1998;22 teeth in 7-year-old Swedish children. Int J Suppl:63-67 Paediatr Dent 2001;11:11-17. Oral Pathol Oral Radiol 7. Melnick M, Shields ED, El-Kafrawy AH. 26. Knezevic A, Travan S, Tarle Z, Sutalo J, Endod 2001 Feb;91(2):244-51. Jankovic B, Ciglar I. Double tooth. Coll Tricho-dento-osseous syndrome: a [From the Department of scanning electron microscopic analysis. Antropol 2002;26:667-672. Clin Genet 1977;12:17-27. 27. Tasa GL, Lukacs JR. The prevalence and Oral and Maxillofacial 8. Aldred MJ, Savarirayan R, Lamande SR, expression of primary double teeth in Radiology Tokyo Dental western India. ASDC J Dent Child Crawford PJ. Clinical and radiographic Clinic, Japan and the features of a family with autosomal 2001;68:196-200. dominant with 28. Mader CL, Fusion of teeth. J Am Dent University of Louisville, USA.] taurodontism. Oral Dis 2002;8:62-68. Assoc 1979;98:62-64. 9. Varrela J, Alvesalo L, Mayhall 29. Nadkarni UM, Munshi A, Damle SG. Unusual presentation of talon cusp: two This study compares the J.Taurodontism in 45,X females. J Dent panoramic imaging qualities Res 1990 ; 69:494-495. case reports. Int J Paediatr Dent 10. Hillebrand U, Mohr C, Plewa G. 2002;12:332-335. of Kodak Ektavision, Agfa Taurodontism in patients with sex 30. McNamara T, Haeussler AM, Keane J. OrthoLux panoramic radio- Facial talon cusps. Int J Paediatr Dent chromosome anomalies. Dtsch Z Mund graphic film, and Agfa ST8G Kiefer Gesichtschir 1990;14:187-189. 1997;7:259-262. 11. Lebel S, Trinkaus E. Middle Pleistocene 31. Goncalves A, Goncalves M, Oliveira DP, films in combination with human remains from the Bau de Goncalves N. Dens invaginatus type III: Kodak versus Agfa intensify- report of a case and 10-year radio- l’Aubesier: J Hum Evol 2002;43:659-685. ing screens. The density 12. Bailey SE. A closer look at Neanderthal graphic follow-up. Int Endod J postcanine dental morphology: the 2002;35:873-879. response and resolution of mandibular dentition. Anat Rec 32. Gound TG. Dens invaginatus—a pathway panoramic radiographic film/ to pulpal pathology: a literature review. 2002;269:148-156, intensifying screen combina- 13. Toure B, Kane AW, Sarr M, Wone MM, Fall F. Pract Periodontics Aesthet Dent Prevalence of taurodontism at the level 1997;9:585-594. tions was evaluated by of the molar in the black Senegalese 33. McCulloch KJ, Mills CM, Greenfeld RS, means of Hurter and Driffield population 15 to 19 years of age. Coil JM. Dens evaginatus from an curves, modulation transfer Odontostomatol Trop 2000;23:36-39. orthodontic perspective: report of 14. Constant DA, Grine FE. A review of several clinical cases and review of the function (MTF), and noise- taurodontism with new data on literature.Am J Orthod Dentofacial equivalent number of quanta indigenous southern African populations. Orthop 1997;112:670-675. (NEQ). Image clarity of Arch Oral Biol 2001;46:1021-1029. 34. Stecker S, DiAngelis AJ. Dens 15. Darwazeh AM, Hamasha AA, Pillai K evaginatus: a diagnostic and treatment selected anatomical struc- Prevalence of taurodontism in Jordanian challenge. J Am Dent Assoc tures was also rated. The ISO dental patients. Dentomaxillofac Radiol 2002;133:190-193. speed for the Agfa OrthoLux 35. Kannan SK, Suganya, Santharam H 1998;27:163-165. film/screen combinations 16. Ruprecht A, Batniji S, el-Neweihi E. The Supernumerary roots.Indian J Dent Res incidence of taurodontism in dental 2002;13:116-119. was the fastest, and the patients. Oral Surg Oral Med Oral Pathol 36. Morrow JW, Hylin DL. Supernumerary Kodak Ektavision system was rooted primary central incisors: report of 1987;63:743-747. the slowest. The average 17. MacDonald-Jankowski DS, Li TT. seven cases. ASDC J Dent Child Taurodontism in a young adult Chinese 1993;60:337-338. gradient for the Agfa ST8G population. Dentomaxillofac Radiol 37. Cholitgul W, Drummond BK. Jaw and system was relatively steep tooth abnormalities detected on 1993;22:140-144. in comparison with those for 18. Hayashi Y. Endodontic treatment in panoramic radiographs in New Zealand taurodontism. J Endod 1994;20:357-358. children aged 10-15 years. N Z Dent J the other film/screen combi- 19. Kjaer I. Morphological characteristics of 2000;96:10-13. nations indicating a narrower dentitions developing excessive root

6 recording latitude. The MTFs based New Zealand longitudinal teeth and one-third of the man- for the Kodak Ektavision film study. Oral Surg Oral Med Oral dibular teeth had erupted by age (a measure of spatial resolu- Pathol Oral Radiol Endod 26, with 22.6% of the maxillary tion) were higher than those 2001;92:150-155. [From the De- teeth and 32 % of the mandibular for the Agfa films, irrespective partment of Oral Health, School teeth having been extracted. It is of the screen combination of Dentistry, University of Otago, concluded that other than hori- used. The NEQ for the Agfa Dunedin, New Zealand.] zontally impacted third molars, a ST8G film/screen combina- substantial proportion of other tions was lower than that for This study evaluated the pres- impaction types do erupt fully, the other film/screen combi- ence and impaction status of and radiographically apparent nations tested. The NEQ for third molars in persons at age 18 impaction in late adolescence the Kodak Ektavision film/ years, as well as the observed should not be sufficient grounds screen combinations was well changes in their clinical status for their prophylactic removal in within the high-frequency between ages 18 and 26 years. the absence of other clinical range; whereas Agfa OrthoLux This prospective cohort study indications. combined with either the was performed on 821 individuals Kodak Ektavision imaging for whom panoramic radiographs Supernumerary teeth: Sequential screen or the Kodak Lanex were taken at age 18 years. For panoramic radiographs evi- Regular imaging screen each tooth, its radiographic denced the late development of produced a NEQ similar to impaction status at age 18 years a post-dentition supplemental that of the Kodak Ektavision was compared with the clinical supernumerary tooth. film/screen combinations in status by age 26 years. Of the Gibson N. A late developing the low-frequency range. 2857 third molars assessed at mandibular premolar supernu- Agfa OrthoLux was perceived age 18 years, 93 % were followed merary tooth. Aust Dent J 2001 to provide clearer images of clinically to age 26 years. Ap- Mar;46(1):51-2. [From the Torbay the selected anatomical proximately 55 % of the teeth Hospital, Torquay, UK.] details than Agfa ST8G, and that were not impacted by age the Agfa OrthoLux/Agfa 18 had erupted by 26 years. Of Supplemental supernumerary Ortho Regular 400 combina- the teeth that were impacted by premolar teeth can become tion was not significantly age 18, 34 % had fully erupted by radiographically apparent at a different from the Kodak age 26, 31 % had been extracted stage much later than that for the Ektavision/Kodak Lanex and 13 % remained unerupted. Of regular dentition. The case of a Regular combination in terms the maxillary teeth that were patient who developed a man- of perceived image quality. categorized as “impacted” at dibular premolar supernumerary Agfa OrthoLux is an improve- age 18 years, 36 % had fully tooth between the age of 11 and ment over Agfa ST8G in film erupted by age 26, whereas 26 % 20 years is reported. Evidence for speed, spatial resolution, of the mandibular teeth had the late development of the granularity, and perceived done so (P <.01). Fewer mandibu- supernumerary tooth came from diagnostic image quality. The lar teeth than maxillary teeth consecutive panoramic radio- Agfa OrthoLux/Agfa Ortho remained unerupted by the time graphs. Regular 400 combination; the patient was 26 years old (27 however, did not exceed the % and 41 %, respectively; P <.01), Jaw cysts: Panoramic images Kodak Ektavision film/Kodak but there was no significant were used to compare the radio- Ektavision imaging screen difference between the jaws in graphic features of the mandibu- combination in terms of the proportion of impacted lar odontogenic keratocysts and resolution, granularity, and teeth at age 18 years that had the dentigerous cysts associated perceived image quality. been extracted by age 26 years with third molars. (both 30 %). For mesioangularly Tsukamoto G, Sasaki A, Akiyama Third molars that appear impacted third molars, 39 % of T, Ishikawa T, Kishimoto K, impacted at age 18 y can maxillary teeth and 20 % of Nishiyama A, Matsumura T. A often erupt into normal mandibular teeth had fully radiologic analysis of dentiger- by age 26 y. erupted by age 26, whereas ous cysts and odontogenic Kruger E, Thomson WM, almost one-third of each had keratocysts associated with a Konthasinghe P. Third molar been extracted. Of the mandibular third molar. Oral Surg outcomes from age 18 to 26: distoangularly impacted third Oral Med Oral Pathol Oral Radiol findings from a population- molars, 20 % of the maxillary Endod 2001 Jun;91(6):743-47. [From

7 the Department of Oral and dental age of patients; however, standards for accurate dental Maxillofacial Surgery II, there is a need to develop age assessment. Okayama University Dental separate assessment standards School, Okayama, Japan.] for different population groups. Stylohyoid ossification: Ossifica- Davidson LE, Rodd HD. Interrela- tion within the stylohyoid chain is The objective was to discriminate tionship between dental age demonstrable on panoramic radiographically between denti- and chronological age in Somali radiography. Such ossification gerous cysts and odontogenic children. Community Dent Health increases with increased patient keratocysts associated with a 2001;18:27-30. [From the age. mandibular third molar. Panoramic Department of Child Dental Krennmair G, Lenglinger F, radiographs were studied for Health, School of Clinical Den- Lugmayr H. Variants of ossifica- cases of dentigerous cysts (44 tistry, University of Sheffield, UK]. tion of the stylohyoid chain. Rofo patients, 45 cysts) and odontoge- Fortschr Geb Rontgenstr Neuen nic keratocysts (15 patients, 16 This cross-sectional study com- Bildgeb Verfahr 2001 cysts). All cysts were associated pared dental age with chrono- Mar;173(3):200-4. [From the Clinic with a mandibular third molar. The logical age in Somali children for Oral and Maxillofacial panoramic images were analyzed under 16 years of age and age- Surgery, University of Vienna, with reference to the patients’ and gender-matched white Austria.]. ages and symptoms. The mean Caucasian children, all resident in age of patients in whom odonto- Sheffield, England. The sample Panoramic radiographs of 380 genic keratocysts were detected group comprised 162 subjects: 84 patients (including 718 radio- was less than that of patients Somali and Caucasian boys graphs clearly depicting the having dentigerous cysts. The (mean age 10.6 y) and 78 Somali regions of the stylohyoid chains), mean size of odontogenic and Caucasian girls (mean age were subdivided into 4 age keratocysts was larger than that 11.2 y). The dental age was as- groups (= 20 y, 21-40 y, 41-60 y, > 60 of dentigerous cysts. The mean sessed for each subject, using y), and were reviewed and distance from the second to the their existing panoramic radio- examined for the incidence, third molar for dentigerous cysts graphs. Comparisons of the length and location(s) of ossifica- was greater than that for odonto- difference between dental age tions in the stylohyoid chains. genic keratocysts. While there and chronological age were Elongation of the styloid process was a significant correlation made for each gender and both and/or ossification of the stylohy- between the lesion size and the ethnic groups. Independent oid ligament was found in 221 distance between the second sample tests were employed for (30.8%) of the reviewed stylohy- and third molars in the dentiger- statistical analysis. The level of oid chains. With increasing age, ous cyst versus the odontogenic significance was set at p < 0.05. there was an increase in the keratocyst, the patients’ ages did The mean difference between prevalence and length of stylohy- not significantly correlate with dental age and chronological oid ossifications (p < 0.01). A these features: Odontogenic age was found to be 1.0 years for significant linear correlation keratocysts tended to grow more Somali boys, 0.2 years for Cauca- between the length of the rapidly than dentigerous cysts, sian boys, 1.2 years for Somali girls, stylohyoid ossifications and age but did not cause as much tooth and 0.5 years for Caucasian girls. was only found in the young age displacement. No evidence was The difference between dental group (= 20 y; p < 0.01). In this age found for either cyst type to and chronological age was group, there was also a predomi- develop gradually from the time significantly greater in Somali nance of isolated locations of of initiation of the dental follicle subjects than in Caucasian ossification in the superior stylo- or the dental lamina. They rather children. The authors conclude hyoid segment. With increasing arose randomly at various stages. that Somali children are more patient age, the presence of dentally advanced than their ossifications in the middle and Dental age assessment: Pan- Caucasian peers. This finding inferior stylohyoid segments and oramic radiography provides an underlines the need for popula- combinations of ossified variabili- excellent means of assessing the tion-specific dental development ties were prominent. The authors conclude that stylohyoid ossifica- tion shows age-related differ- ences in incidence, length and topography.

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