Original Article Three‑dimensional evaluation of the mandibular third molars’ development in unilateral crossbite patients: A cone beam computed tomography study Koray Halicioglu1, Mevlut Celikoglu2, Suleyman Kutalmis Buyuk3, Ahmet Ercan Sekerci4, Faruk Izzet Ucar5, Ibrahim Yavuz3 1Department of Orthodontics, Faculty of Dentistry, Abant Izzet Baysal University, Bolu, Turkiye, 2Department of Orthodontics, Faculty of Dentistry, Akdeniz University, Antalya, Turkiye, 3Department of Orthodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkiye, 4Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Erciyes University, Kayseri, Turkiye, Correspondence: Dr. Mevlut Celikoglu 5Department of Orthodontics, Faculty of Dentistry, Email: [email protected] Selcuk University, Konya, Turkiye ABSTRACT Objectives: The aim was to investigate mandibular third molar (3M)’s maturation in the crossbite and normal sides by two‑ and three-dimensional analyses using cone beam computed tomography (CBCT). Materials and Methods: A retrospective study was performed using CBCT of 25 patients (16 females and 9 males; mean age: 16.8 ± 2.9 years) with unilateral posterior crossbite. The formation stages and the volume of the mandibular 3Ms were evaluated by means of CBCT data of the patients without knowing the crossbite side of the patients. Results: Statistically no significant differences were found in the development of the 3Ms between the crossbite and the control sides, whereas the volume of 3M was found to be less in the crossbite side than in the normal side (P = 0.021). Conclusions: A volume of 3M was found to be less in the crossbite side than in the normal side. Key words: Dental growth, dental maturation, third molar development, unilateral crossbite INTRODUCTION new techniques for acquiring three‑dimensional dental radiographs, resulting in good image quality Radiography is generally used in determining with low radiation dose. In addition, CBCTs provide dental maturation and two‑dimensional panoramic an opportunity to analyze volumetric measurements radiographs are mainly used in radiography as of teeth. Cameriere et al.[5] emphasized that seen in the dental and forensic literature. However, volumetric study with CBCT would be the best different dental age estimation methods have method for dental age estimation. Yang et al.[4] first been used to measure tooth development, which describe an approach to dental age estimation by include diagrams,[1] charts,[2] and definition of CBCT using the ratio of pulp/tooth volume that the formative stages[2,3] at present. Cone beam could be calculated for living individuals. Maret computed tomography (CBCT) allows obtaining et al.[6] indicated that to improve age estimation goal, three‑dimensional images of the tooth. Yang et al.[4] including the volume of dental tissues and their mentioned that the clinical use of CBCT has shown ratio, “further investigation should aim: To acquire How to cite this article: Halicioglu K, Celikoglu M, Buyuk SK, Sekerci AE, Ucar FI, Yavuz I. Three-dimensional evaluation of the mandibular third molars’ development in unilateral crossbite patients: A cone beam computed tomography study. Eur J Dent 2014;8:389-94. Copyright © 2014 Dental Investigations Society. DOI: 10.4103/1305-7456.137653 European Journal of Dentistry, Vol 8 / Issue 3 / Jul-Sep 2014 389 Halicioglu, et al.: Development of mandibular third molars larger sample sizes in order to reduce standard approval was not required due to the archival nature errors of age estimation, study the effect of several of the research. However, as a usual protocol, all the factors on model parameters, and investigate the patients (or parents) signed an informed consent use of all types of teeth together”. Limited number agreeing to the use of the patients’ data (age, gender, of studies is available on the issue of ratio of pulp/ medical history, etc.) for scientific studies. tooth volume. Dental age estimation is usually done on the mandibular incisor,[7] canine,[8] or premolar[9] All images were obtained in the supine position by that is, always the monoradicular teeth[4,10] in the using CBCT (NewTom 5G, QR Verona, Italy). The afore‑mentioned studies. Nevertheless, no study has scanning time was 18 s, collimation height 13 cm, investigated the use of tooth germ volume for dental exposure time 3.6 s, and voxel size 0.3 mm3. Patients in the study group met the following inclusion criteria: age estimation in multiradicular teeth. • No history of trauma, developmental and acquired In addition to this, it is a well‑known fact that dental craniofacial disorders or maxillofacial surgery development is a multi‑factorial phenomenon.[11] Garn prior to orthodontic treatment. et al.[12] in their study have reported in 1965 that they • No missing tooth (excluding maxillary 3Ms) and thought genes, harmonies, and even calories have no systemic disease. an important role in tooth development. However, • Skeletal Class I (determined by ANB; 0‑4°) and environmental factors are now better known to have normodivergent facial pattern (determined by a very important role in the dental development.[2] SN‑GoGn angle; 32° ± 5°). • Unilateral crossbite of at least two teeth determined Orthodontic malocclusion is one of the most prominent by plaster models (11 patients had all teeth in of environmental factors. Orthodontic malocclusions crossbite, 8 patients had three teeth in crossbite on the sagittal,[13] vertical[14] and even horizontal[15] and 6 patients had two teeth in crossbite). dimensions have been reported to have an effect on dental development. All records were examined in axial slices, and patients who had two or more unilateral posterior Posterior crossbite is characterized as any abnormal crossbite teeth were determined using the same buccopalatinal relationship between mandibular device (NewTom 5G, QR Verona, Italy) [Figure 1]. and maxillary molars, premolars, or both in centric Primary reconstructions of the data were performed occlusion.[16] Unilateral crossbite is associated with with the Mimics software (Materialise HQ, Leuven, asymmetric muscular function and asymmetric bite Belgium). Second, the exported digital imaging and force.[17] Uysal et al.[15] indicated that the crossbite communication in medicine (DICOM) files were patient presented with a tendency to delayed viewed, and segmentations of the mandibular 3Ms dental maturation. Nevertheless, mandibular third were carried out using software. Observations were molars (3Ms) were not included in their study. In made regarding the patient’s sex, chronological age, addition to this, there is no study investigating the ANB, and SN‑GoGn angles. development of 3Ms in the crossbite and normal sides. In light of this fact, the aim of this study was to Evaluation of dental maturation and dental investigate mandibular 3Ms maturation and volume volume in the crossbite side and to compare them with the Panoramic radiograms were obtained by the Mimics 3Ms in the normal sides by two‑dimensional and software (Materialise HQ, Leuven, Belgium), and dental three‑dimensional analyses using CBCT data. MATERIALS AND METHODS A retrospective study was performed using CBCT data of 25 patients (16 females and 9 males; aged 15‑23 years), selected randomly from the archive of Faculty of Dentistry in Erciyes University. CBCT scans of these patients were previously obtained as a part of the diagnostic records for orthognathic surgery, temporomandibular dysfunction, and impacted canine; and for this reason they were not Figure 1: Unilateral crossbite shown in a cone beam computed subjected to additional radiation. Ethics committee tomography image 390 European Journal of Dentistry, Vol 8 / Issue 3 / Jul-Sep 2014 Halicioglu, et al.: Development of mandibular third molars development of the 3Ms was evaluated according The normality test of Kolmogorov–Smirnov was to the method of Demirjian et al.[2] The formation applied to the data, and all data were found stages of the tooth germs were evaluated based on normally distributed. Thus, the statistical evaluations the formative condition of the crowns and roots of the of these data were performed using parametric mandibular 3Ms. This method divides the formation tests. Student’s t‑test was used to assess gender of the crowns and roots of permanent teeth into eight differences in the patient’s chronological age, ANB, stages. The formation stages are shown in Figure 2. The and SN‑GoGn angles. A paired t‑test was used to formation stage of the mandibular 3M on the side of compare the differences in the developmental stages the crossbite was evaluated. The formative condition and volume of the 3Ms between the crossbite and of the 3M on the other side of the same jaw was used control sides. Since no gender difference was present as the control [Figure 3]. DICOM files were imported for mandibular 3Ms’development stages and volume, in a CBCT diagnostic and treatment planning software the data from both sexes were pooled. A linear allowing for tooth volume calculations. The program regression analysis was performed to evaluate the automatically calculated the volume of the obtained effect of the number of teeth in crossbite. All data three‑dimensional images of the tooth [Figure 4]. were analyzed with SPSS for Windows (version 15.0, SPSS, Chicago, Illinois). P < 0.05 was considered to All measurements were carried out by a be statistically significant. dentomaxillofacial radiologist without knowing the crossbite side and thus a blinding was performed. RESULTS Statistical evaluation To test the reproducibility of the assessments of dental Demographic features of the patients included to the developmental stages and volume of mandibular study are shown in Table 1. Student’s t‑test showed no 3Ms, the same investigator re‑evaluated 15 randomly significant sex differences for skeletal facial patterns selected CBCTs 2 weeks after the first evaluation. and chronological ages and thus both genders Intra‑class correlation coefficients were performed to presented similar characteristic features. assess the reliability of volumetric measurements as described by Houston.[18] The coefficients of reliability Table 1: Demographic features of the subjects according to the Houston method[18] for volumetric included to the study measurements were 0.92 (mandibular right molar Study samples n ANB (°)* SN‑GoGn (°)* CA (years)* volume) and 0.98 (mandibular left molar volume), Females 16 2.8±1.2 34.1±5.1 16.2±1.9 confirming measurement reliability. Kappa coefficients Males 9 3.2±1.4 33.4±3.6 18.1±4.2 were used to evaluate agreement between the first and Total 25 3.0±1.2 33.8±4.6 16.8±2.9 second dental maturity assessments and Kappa values *No significant difference tested by Student’s t-test. n: Number, were found to be above 0.90. CA: Chronological age a b c d e f g h Figure 2: The eight stages of tooth development according to Demirjian method European Journal of Dentistry, Vol 8 / Issue 3 / Jul-Sep 2014 391 Halicioglu, et al.: Development of mandibular third molars Figure 3: The formative condition of the third molar on the other side of the same jaw was used as the control Third molars’ development stages and volume in relation to crossbite presence are shown in Table 2. Figure 4: Volumetric measurement of third molar on the cone beam Paired t‑test showed that no statistically significant computed tomography images differences were found in the development of the mandibular 3Ms between the crossbite and control Table 2: Third molar development stage in relation sides (P = 0.714). In addition, when we evaluated to cross bite presence patients one by one, we detected differences in seven Parameters Crossbite side Normal side P* patients according to the developmental stages of the Root development stage 5.54±1.64 5.50±1.67 0.714 3Ms. On the other hand, 18 of 25 patients’ development 3M volume (mm3) 529.81±199.01 578.52±217.43 0.021 of the 3Ms were the same. Although three patients had *The result of paired t-test, 3M: Third molar one developmental stage delay of the mandibular 3M in the crossbite side, the other four patients had one Dental development is a multi‑factorial phenomenon. developmental stage accelerated. Malocclusions in the sagittal, vertical, and horizontal dimensions[13‑15] were previously shown to affect dental Because Student’s t‑test showed no significant sex development. Therefore, patients who were included differences for the volume parameters of the 3Ms, in this study were compatible with the horizontal the data for both genders were pooled. In contrast to and vertical dimensions as shown in Table 1. Lately, developmental stage similarities, paired t‑test showed it was shown that children with hypodontia showed statistically significant differences for the volume a significant delay in dental development when of the mandibular 3Ms between the crossbite and compared with case controls.[21] To eliminate those control sides (P = 0.021). The volume of mandibular factors, patients with hypodontia were not included 3M in the crossbite side was less than the volume to this study. Since above factors affecting dental of 3M in the control side (529.81 ± 199.01 mm3 and development was eliminated, the effects of unilateral 578.52 ± 217.43 mm3, respectively).Results of the crossbite might be better understood. regression analysis showed that the number of the teeth in crossbite had no affect on the volume of Panoramic radiographs are noninvasive methods that the mandibular 3Ms (R2 = 0.004; P = 0.714). are used in the formative condition of the teeth.[13,22,23] Dental maturation has been successfully determined DISCUSSION from two‑dimensional panoramic radiographs. However, these radiographic images were made Dental age determination is important in both medical from accumulated two‑dimensional images of the jurisprudence and clinical dentistry.[19] The most horizontal or parallel aspects of the tooth[6] and common method by which dental age assessment therefore, would be difficult to accurately evaluate is done is the method of Demirjian et al.[2] This the development of the teeth, especially 3Ms that classification method distinguishes the first four stages have generally different eruption and formation of crown development (A‑D) and the last four stages anomalies. Furthermore, the entire three‑dimensional of root development (E‑G) so it is easy to use. Dhanjal morphological assessment of 3Ms is not possible with et al.[20] have reported that this method performed panoramic radiographs. However, the clinical use of intra‑ and inter‑examination best for radiographic CBCT has created new opportunities for obtaining stage assessment of 3Ms. Therefore, this method was three‑dimensional tooth radiographs, resulting in used in this study. reasonable fair image quality at a low radiation dose.[4] 392 European Journal of Dentistry, Vol 8 / Issue 3 / Jul-Sep 2014 Halicioglu, et al.: Development of mandibular third molars In a recent paper, Ahlowalia et al.[24] in their study and vertical skeletal anomaly reduced the study have reported that CBCT was an accurate means of sample of the present study. Future studies including measuring the volume of artificially created bone larger study samples and performed on CBCT cavities. Therefore, we used CBCT images to assess archive could be welcome to discuss and confirm maturations and volume of 3Ms. our findings. It was stated that deviation of tooth maturation on the CONCLUSION two sides of the same jaw is frequent and few months of tooth maturation difference can be observed.[25] In As a result, although two‑dimensional data showed this study, no statistically significant difference for that no statistically significant difference was present the mandibular 3M developmental stage between for the development of mandibular 3Ms in the normal the crossbite and the normal sides was present. and crossbite sides, the volume of 3M that was We detected differences only in seven patients in calculated by means of CBCT was found to be less in relation to the developmental stages of the 3Ms. the crossbite side than in the normal side. Although there was no difference in dental maturation as assessed by two‑dimensional analyses method, REFERENCES there were statistically significant volume differences between the crossbite and control sides (P = 0.021). It 1. Schour I, Massler M. 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