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Dental Computed Tomographic Imaging as Age EstimationMorphological Analysis of the Third Molar of a Group of Turkish Population

Kenan Cantekin, DDS, PhD,* Ahmet Ercan Sekerci, DDS,þ and Suleyman Kutalmis Buyuk, DDSþ

Abstract: Computed tomography (CT) is capable of providing accu-rate and measurable 3-dimensional images of the third molar. The aimsof this study were to analyze the development of the mandibular thirdmolar and its relation to chronological age and to create new referencedata for a group of Turkish participants aged 9 to 25 years on the basis ofcone-beam CT images. All data were obtained from the patients’ recordsincluding medical, social, and dental anamnesis and cone-beam CTimages of 752 patients. Linear regression analysis was performed toobtain regression formulas for dental age calculation with chronologicalage and to determine the coefficient of determination (r2) for each sex.Statistical analysis showed a strong correlation between age and third-molar development for the males (r2 = 0.80) and the females (r2 = 0.78).Computed tomographic images are clinically useful for accurate andreliable estimation of dental ages of children and youth.

Key Words: forensic medicine, dental age assessment, Demirjian,orthodontics, criminology

(Am J Forensic Med Pathol 2013;34: 357Y362)

Dental age determination is important to learnwhether childrenand youth are growing properly and is especially useful in

orthodontics, pediatric dentistry, pediatric endocrinology, foren-sics, and anthropology.1Y6 For both the pedodontist and the or-thodontist, knowing a child’s growth and developmental status isespecially important in diagnosis and treatment planning.1Y6

Dental developmentYbased age estimation is 1 of the mostreliable indicators of chronological age.6 Radiographic assess-ment of the degree of third-molar formation is a major part offorensic age estimation of adolescents and young adults. Be-cause of the fact that all other permanent teeth have finishedtheir development in this age group,3,7 third molars representthe only teeth still in development. In addition, it can beperformed simply, can be reproduced, and is cheap.

Classic methods for forensic dental identification are theclinically used radiological documentation techniques such asdental periapical radiographs, bitewing films, and panoramictomographs (OPGs). An alternate imaging modality that is be-ginning to make inroads into medicolegal death investigationaround the world is computed tomography (CT).8Y10 The clini-cal introduction of cone-beam CT creates new opportunities toget 3-dimensional (3D) tooth radiographs. It has been shownthat CT scans cause no magnification errors due to geometricdistortion, which is a common problem in conventional radi-ography.11,12 Furthermore, CT is capable of providing accurate

and measurable 3D images of the third molar that can be rotatedin space, thus eliminating the problem of unfavorably angulatedteeth and teeth superimposed on adjacent structures at a lowradiation dose (skin dose, 1.19 mSv13; total dose, 20 KSv perexamination).14

Many research articles have reported age estimation in chil-dren and/or adolescents through evaluating third-molar minerali-zation on different populations; so far,3,15Y25 after reviewing theliterature, only 1 report26 was seen on the research of age esti-mation in children and adolescents that used radiological docu-mentation as cone-beam CT (CBCT). Bassed et al26 report somedisagreements when Demirjian scores for conventional radio-graphs and CT images were compared. Therefore, the aims of thisstudy were to analyze the development of the mandibular thirdmolar and its relation to chronological age and to create newreference data for a group of Turkish participants aged 9 to25 years on the basis of CBCT images.

MATERIALS AND METHODS

SamplesIn this retrospective study, all data were obtained from the

patients’ records including medical, social, and dental anam-nesis and CBCT images of 752 patients who presented to theOral and Maxillofacial Radiology service, Dentistry Faculty atthe Erciyes University, Turkey. All records were selected froma Turkish population from the Cappadocia region of Turkey.Cone-beam CT images had been taken because of the patients’previous dentomaxillofacial problems.

The CBCT unit selected for this study was the NewTom3G (QR, Verona, Italy). The exposure parameters used to ac-quire the images were 110 kilovolt (peak), 1 to 15 mA, 17 � 13cylindrical field of view, and voxel size of 0.25 mm and expo-sure time of 36 seconds. Table 1 shows the age and sex distri-bution of the sample sets. Ethical approval was received fromthe Ethical Committee of Dentistry Faculty.

The CBCT images were analyzed with the inbuilt software(NNT) in a Dell Precision T5400 workstation (Dell, RoundRock, Tex), with a 32-in Dell LCD screen with a resolution of1280 � 1024 pixels in a darkroom. The contrast and the bright-ness of the images were adjusted using the image processing toolin the software to ensure optimal visualization. Third-molar im-ages were captured using the 3D maximum intensity projectionbone algorithm, which provides what is, in effect, a 3D radio-graph that can be rotated in space to optimize the view of the longaxis of the tooth and the degree of development of the crownand the root. Selecting and moving the cursor on 1 image tochange the center of view altered the reconstructed slices in3 orthogonal planes. Tomography sections of 0.150 mm in theaxial, coronal, and sagittal planes were created. Cross-sectionalimages (axial, coronal, and sagittal image) were transmitted to apersonal computer in the digital imaging and communicationsin medicine format and reconstructed into multiplanar recon-struction images using the digital imaging and communicationsin medicine viewer: ExaVision SX version 1.13 (Ziosoft, Inc,

ORIGINAL ARTICLE

Am J Forensic Med Pathol & Volume 34, Number 4, December 2013 www.amjforensicmedicine.com 357

Manuscript received April 28, 2012; accepted January 18, 2013.From the Departments of *Pediatric Dentistry, †Oral Radiology, and

‡Orthodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey.Reprints: Kenan Cantekin, DDS, PhD, Department of Pediatric Dentistry,

Faculty of Dentistry, Erciyes University, 38039, Kayseri, Turkey.E-mail: [email protected]

The authors report no conflicts of interest.Copyright * 2013 by Lippincott Williams & WilkinsISSN: 0195-7910/13/3404Y0357DOI: 10.1097/PAF.0000000000000054

Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

mailto:[email protected]

Tokyo, Japan). These views were then adjusted for contrast toobtain optimum visualization of the tooth crown and the root.

The selection criteria included the following: (1) Turkishparticipants aged between 9 and 25 years; (2) born after a nor-mal gestation period and healthy; and (3) having normalgrowth, development, and dental conditions. The exclusioncriteria included the following: (1) unknown age, (2) no thirdmolar, and (3) having had significant head trauma that poten-tially affected visualization of the third molars. Eleven filmswere excluded for unknown chronological age, and 96 filmswere excluded for agenesis of the lower wisdom teeth. The finalsamples, therefore, consisted of 649.

ExaminationThe mineralization status of the third molars was assessed

using the formation stages described by Demirjian and Gold-stein27 (Fig. 1), based on 8 stages of tooth formation. All assess-ments were carried out by 2 well-trained investigators (pediatricdentist and maxillofacial radiologist) without any knowledge ofthe participants’ chronological ages.

To assess reliability, 70 (10%) randomly selected radio-graphs were reexamined 30 days after the initial examination bythe same observers, and intraobserver agreement was determinedusing the paired t test.

Statistical AnalysisThe Kolmogorov-Smirnov test was used to test the normality

of distribution of the developmental stages of both mandibularthird molars in each sex and age group. An independent t test wasperformed for sex and age to determine the relationship betweentooth developments. Linear regression analysis was performed toobtain regression formulas for dental age calculation with chro-nological age and to determine the coefficient of determination(r2) for each sex. Statistical analysis was performed using theStatistical Package for the Social Sciences 15.0 (Statistical Pack-age for the Social Sciences Inc, Chicago, Ill) for Windows.

RESULTSRepeated scorings of a subsample of 70 radiographs indi-

cated no significant intraobserver difference (P 9 0.05). Intra-observer consistency was rated at 100%.

The mean T SD age was 16.57 T 4.29 years, made up of330 males (mean T SD age, 16.58 T 4.43) and 314 females(mean T SD age, 15.57 T 4.21).

Data were subgrouped by sex and age for both left andright mandibular hemiarches. Tables 2 and 3 show the mean ageand SD for stages A to H in the left and right third mandibularmolars for the males and the females. A statistically signifi-cant sexual dimorphism was noted for 38 and 48 at stage C(P G 0.05), 0.29 and 1.07 years earlier in the males than in the

TABLE 1. Distribution of Age and Sex of the Sample

Age, y Male Female Total

9 12 9 2110 26 15 4111 17 28 4512 29 24 5313 29 24 5314 27 23 5015 25 24 4916 13 30 4317 17 25 4218 27 10 3719 18 24 4220 16 16 3221 26 21 4722 10 22 3223 19 8 2724 19 16 35Total 330 319 649

FIGURE 1. The Demirjian classification of tooth mineralizationmodified in accordance with CT images.

Cantekin et al Am J Forensic Med Pathol & Volume 34, Number 4, December 2013

358 www.amjforensicmedicine.com * 2013 Lippincott Williams & Wilkins


females, respectively. The correlation between chronologicalage and the Demirjian stages is expressed in Figures 2 and 3.

As can be seen, the third molars had reached completecrown calcification (stage D) at age 13 years, ranging from 10.4to 18.1 years (Tables 2 and 3). The first root completion (stageH) was not seen in the males and the females until the age of18 years. Demirjian stages A and B were not observed in the14- to 24-year-old age group. Stage C was not observed in thegroups older than 18 years.

The development of the right and left lower third molarswas compared using paired t test. Statistically significant dif-ferences between the 2 sides were not found (P 9 0.05).

Linear regression coefficients were used to assess thecorrelation between third-molar development and chronologicalage. Statistical analysis showed a strong correlation between ageand third-molar development for the males (r2 = 0.80) and thefemales (r2 = 0.78). The new equations were the following:

For 48:

Males : age ¼ 6 :27 þ 0 :89 development stageFemales : age ¼ 6 :87 þ 0 :87 development stage

For 38:

Males : age ¼ 6 :71 þ 0 :89 development stageFemales : age ¼ 7 :77 þ 0 :87 development stage

DISCUSSIONThe third-molar calcification stage is 1 of the few tools that

can be used to assess age when development is nearing com-pletion.28 However, age estimates based on dental methods haveshortcomings, especially during adolescence when the thirdmolar is the only remaining variable dental indicator. Indeed, agreat variation in position, morphology, and time of formationexists.25 For this purpose, third-molar examination represents 1acceptable alternative, although it is the most variable toothwith regard to time of formation28 and the age of eruption.29

Different methods for evaluating dental maturity have beendefined, based on the observation of distinctive formationstages.23,29Y31 We have chosen the Demirjian method because itis more simple (only 4 stages of root formation on the thirdlower molars) and objective (only changes in shape or pro-portions and no metric estimations are defined). Moreover, re-cent studies verify that the Demirjian classification systemperformed best not only for observer agreement but also for thecorrelation between estimated and true age.22

To date, we have found only 1 published study26 examiningwisdom teeth for age estimation obtained from CT images, afterconducting a bibliographic search in MEDLINE using PubMedand the key words/phrases wisdom teeth, CT, CBCT, and dentalage. Bassed et al26 have compared the developmental scores obtainedfrom both CT images and conventional OPG radiographs, and thedevelopment of the third molar in a sample of 15- to 25-year-old

TABLE 2. Statistical Data of Chronological Mineralization Age of 38

Male Female

Stage n Mean SD Min Max n Mean SD Min Max P

A 14 10.40 0.74 9.10 12.10 12 10.42 1.14 9.00 12.30 NSB 24 11.10 1.28 9.50 13.50 24 11.30 0.94 9.50 12.70 NSC 31 12.47 1.50 9.80 15.60 66 13.16 1.68 10.30 17.90 0.03a

D 71 13.42 1.83 10.50 17.60 30 13.83 2.48 10.50 18.10 NSE 29 15.13 1.26 13.30 17.80 30 14.79 1.42 11.90 17.20 NSF 44 17.71 2.09 13.00 21.20 45 17.78 2.08 13.00 21.60 NSG 48 20.77 2.49 16.30 24.70 61 20.27 2.63 15.10 24.40 NSH 69 21.83 1.93 18.00 24.90 46 22.02 1.93 18.30 24.80 NS

aP G 0.05.

Max indicates maximum; min, minimum; NS, not significant.

TABLE 3. Statistical Data of Chronological Mineralization Age of 48

Male Female

Stage n Mean SD Min Max n Mean SD Min Max P

A 8 10.43 0.96 9.10 12.10 12 10.34 1.08 9.00 12.30 NSB 25 11.05 1.27 9.50 13.50 23 11.33 0.95 9.50 12.70 NSC 31 11.74 1.60 9.80 15.60 17 12.81 2.00 10.30 16.30 0.04a

D 78 13.44 1.73 10.80 17.60 78 13.76 1.96 10.80 17.90 NSE 28 15.25 1.36 13.00 17.90 32 14.80 1.47 11.90 17.20 NSF 45 17.84 1.98 14.00 21.20 44 17.88 2.01 13.00 21.60 NSG 49 20.95 2.50 16.30 24.70 63 20.30 2.61 15.10 24.40 NSH 66 21.79 1.95 18.00 24.90 45 22.00 1.95 18.30 24.80 NS

aP G 0.05.

Max indicates maximum; min, minimum; NS, not significant.

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Australian population was assessed, suggesting that CT imagingis a more reliable technology for use in dental age estimationthan are OPGs. Therefore, we investigated CT images of 7- to24-year-old Turkish participants to establish Turkish referencedata on third-molar mineralization according to the 8 stagesproposed by Demirjian et al.27

Previous studies that used mineralization of the third molarto establish dental age in the Turkish population have beenpublished.3,25 However, to our knowledge, this is the first studyto supply more reliable reference data on third mandibularmolar mineralization in both sexes for the Turkish populationbecause this is carried on CT images. In a study by Sismanet al,25 a total of 1114 OPGs were taken from subjects ofTurkish origin according to the Demirjian classification to de-termine third-molar mineralization stages (Table 4). Accordingto their findings, there were no statistical differences in third-molar mineralization stages between the left and right jaw seg-ments, but root development stages generally occurred earlier in

the upper third molars than in the lower third molars and amongboys than among girls. Accordingly, the Turkish population wasfound to reach the H stage at a mean age of 22.1 years in malesand 22.6 years in females.25 In addition, Willershausen et al32

studied a total of 1202 OPGs of 602 female and 600 maleprobands of Central and Southern European origin, comingfrom Turkey and other unspecified countries. This study iden-tified the mineralization stages of third molars according to theclassification proposed by Kullman et al.33 According to thisstudy, the Turkish population reached Ac stage, which repre-sents the completed root development, at a mean age of20.6 years; and the Southern European population, at a meanage of 21.1 years. The data for the Central European populationlay in between. Because the differences amounted to 6 months,these are deemed as not significant. Our study determined thatthe Turkish population reached stage H at a mean age of 21.7 yearsin the males and 22.0 years in the females. A comparison be-tween the right and left sides of the lower wisdom teeth did notreveal any significant differences either.

The reliability of the Demirjian method was verified withinterobserver and intraobserver studies. Although agreementbetween decisions made by the same expert (J = 0.896) was‘‘perfect’’ or ‘‘substantial’’ according to the 6-category systemproposed by Landis and Koch,34 the J value calculated tomeasure agreement between decisions made by different experts(reproducibility; 0.692) can be considered only ‘‘good’’ or‘‘useful for some purposes.’’34 In this study, intraobserver value

FIGURE 2. The correlation between chronological age andDemirjian stages for 38.

FIGURE 3. The correlation between chronological age andDemirjian stages for 48.

TABLE 4. Comparison of Dental Ages, Determined on OPGsand CT Wisdom Teeth Images, According to the DemirjianMethod for the Same Population

Stage Sex

OPG Images CT Images

P

A Group ofTurkish

Population inCappadocia

Region

A Group ofTurkish

PopulationCappadocia

Region

Sisman et al,25

2007 Our Study

n Mean SD n Mean SD

A Male 72 11.53 3.44 8 10.43 0.96 NSFemale 101 12.64 4.48 12 10.34 1.08 0.04a

B Male 70 11.60 1.52 25 11.05 1.27 NSFemale 68 11.44 1.69 23 11.33 0.95 NS

C Male 58 12.22 1.85 31 11.74 1.60 0.00a

Female 56 12.46 1.83 17 12.81 2.00 NSD Male 40 12.90 1.50 78 13.44 1.73 NS

Female 75 13.60 2.24 78 13.76 1.96 0.03a

E Male 31 14.42 1.69 28 15.25 1.36 NSFemale 36 15.42 2.40 32 14.80 1.47 0.00a

F Male 20 16.90 1.50 45 17.84 1.98 NSFemale 32 16.84 2.10 44 17.88 2.01 NS

G Male 26 18.08 2.38 49 20.95 2.50 0.00a

Female 48 19.29 2.32 63 20.30 2.61 NSH Male 63 22.10 2.87 66 21.79 1.95 0.00a

Female 104 22.66 2.18 45 22.00 1.95 NSaP G 0.05.

NS indicates not significant.




was maximum (1.00) and higher to those obtained from OPGsby others.35

Our results with regard to sex agree, in general terms, withthose reported by previous studies of third-molar develop-ment.31,36Y38The mean ages at stage H were similar for bothsexes, whereas in stage C, some sexual dimorphism was evi-dent, with third-molar maturity commonly occurring earlier inthe males than the females. Sexual dimorphism was confirmedby logistic regression analysis, which showed that mineraliza-tion of teeth 38 and 48 was more advanced in the males than thefemales in a group of Turkish population evaluated in this study.

Statistical analysis shows stronger correlation for themales (r2[38] = 0.80, r2[48] = 80) than the females (r2[38] = 0.75,r2[48] = 75). In agreement with our data, Prieto et al37 andSisman et al25 found stronger correlations for males (r2 = 0.54and r2 = 0.65, respectively) than for females (r2 = 0.45 andr2 = 0.61, respectively). On the other hand, Liversidge39 foundthat the mean age for most stages between Bangladeshi boysand girls was similar, except for crypt. This diversity could beexplained by the differences in the selected age range of thestudy populations. In addition, in previous studies, the valuesof r2 were observed within a wide range and in a low level,from 0.45 to 0.65. However, in our study, compared with thewisdom teeth morphological analyses on OPG, a much lowerr2 range and the highest r2 values were obtained, 75 and 80.This is important in terms of reflected superiority of CT im-ages, compared with OPGs, in dental age assessment accordingto the Demirjian method. In addition, a newly prepared equa-tion for eastern Turkish children and adolescents using linearregression, proposed by Demirjian, will be very useful for fo-rensic age determination through third-molar mineralization.

CONCLUSIONSA referable database of developmental stages of wisdom

molars in a population of Turkish children and youths wasestablished according to the Demirjian classification system onCT images. For dental age estimation of these subjects, 4 re-gression formulas were obtained for both females and males.Computed tomographic images are clinically useful for the ac-curate and reliable estimation of dental ages of children andyouth.

A similar database collection of population origin mayreveal in further studies more specific age-estimation tech-niques and possible differences or agreements in dental devel-opment between members of diverse nationalities or distinctethnic groups.

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