Journal of Oral and Maxillofacial Radiology

: 2019  |  Volume : 7  |  Issue : 3  |  Page : 49--54

An evaluation of the relation between the maxillary third molars and facial proportions using cephalometric image

Sanaz Sadry, Ufuk Ok 
 Istanbul Aydin Universtiy, Dentistry Faculty, Department of Orthodontics, Istanbul, Turkey

Correspondence Address:
Sanaz Sadry
Istanbul Aydin Üniversitesi Dis Hekimligi Fakültesi Ortodonti AD, Istanbul


Objective: The aim of this study was to evaluate the position of the third molars and their relationship with pterygomaxillary fissure vertical dimension patterns and on panoramic and cephalometric images. Materials and Methods: In the present retrospective study, the third molar position classifications, third molar positions of patients with cephalometric and panoramic radiographs, and their relationship with vertical skeletal growth and pterygomaxillary fissure were thoroughly investigated in the light of the preoperative clinical and radiologic records from 200 patients with an indication of third molar extraction, who were admitted to İstanbul Aydın University Faculty of Dentistry Oral, Dental and Maxillofacial Radiology Clinic and Department of Orthodontics due to various reasons. Results: The obtained data were evaluated using SPSS (22.0) package program. Regarding the data analysis, Mann–Whitney U-test statistics was used for the analysis of two-variable data. The vertical facial length's relation with the maxillary third molars, which had been examined on cephalometric and panoramic images, was identified as 50.3% for skeletal Class I, 42.1% for skeletal Class II, 7.6% for skeletal Class III, 70.2% for unilateral, and 29.8% for bilateral. The upper impacted wisdom tooth being unilateral or bilateral does not affect the vertical facial length (P = 0.386). The upper wisdom tooth being impacted unilaterally or bilaterally did not exhibit any statistical difference with the parameters of upper-lower and total anterior facial height and posterior facial height. According to the Chi-square analysis, the correlation between gender and pterygomaxillary fissure variable was found to be statistically insignificant (P > 0.05). According to Mann–Whitney U-test results, no variable was found to be statistically significant based on the molar status (P > 0.05). Conclusion: In the light of this study, prior to treatment planning, if the relationship between the third molars and anatomical formations is determined on cephalometric and panoramic radiographs and it is determined whether the impact of upper wisdom teeth remains effective, consider the therapeutic mechanics used in orthodontic treatments and the complications that may arise during surgical operations. It is emphasized that the necessary measures should be considered beforehand in order to prevent these problems.

How to cite this article:
Sadry S, Ok U. An evaluation of the relation between the maxillary third molars and facial proportions using cephalometric image.J Oral Maxillofac Radiol 2019;7:49-54

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Sadry S, Ok U. An evaluation of the relation between the maxillary third molars and facial proportions using cephalometric image. J Oral Maxillofac Radiol [serial online] 2019 [cited 2020 Jun 6 ];7:49-54
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The teeth that have failed to erupt into their place in normal occlusion beyond the normal eruption period and are completely or partially retained in the bone or soft tissue are defined as “impacted tooth.” Although the eruption period of wisdom teeth varies based on parameters such as genetic characteristics of the individual, feeding patterns, functional involvement of the teeth, and racial variations, it usually takes place between the ages of 20–23 years in males and 21–22 years in females. The teeth that fail to erupt into their normal position within the normal eruption period the following period of 1 year are called “impacted tooth.” The causes that lead to incomplete eruption of wisdom teeth may include local factors such as inadequate space, mechanical impediments (cysts, tumors, tissue hyperplasias, local infections, etc.), traumas, and persistence of postorthodontic treatment results, as well as systemic factors such as vitamin deficiencies, malnutrition, endocrine disorders, and certain specific syndromes (cleidocranial dysostosis, achondroplasia, hydrocephalus, etc.).[1],[2],[3],[4] Panoramic radiographs are the first preferred method for evaluating the relations of the third molars with anatomic formations. Performing the necessary radiological and clinical examinations and taking a thorough medical history before the operation are essential to minimize potential complications that may occur during the surgical extraction of impacted teeth. Cephalometric images play a part in cephalometric evaluation of craniofacial structures, as well as orthodontic and surgical treatment planning. They are used to evaluate the position of maxillary third molars and their relation to anatomical formations, as they provide more detailed information in identification of the relationship between cephalometric measurements and anatomic formations in the region, and offer more precise data before surgical procedures.[5],[6],[7],[8],[9] Vertical anomalies of the face are caused by numerous factors affecting each other during the growth period. These factors include growth differences of the maxilla and mandible, tongue and lip functions, thumb sucking, habits such as long-term use of pacifier and feeding bottle, environmental and functional factors such as nasal airway obstruction, and dentoalveolar development following the eruption of the teeth.[10] Variations in the growth rate of both maxillary sutures and mandibular condyles affect the occurrence of vertical anomalies.[11] The direction of maxillary growth has been reported to vary according to the patient's growth potential. The maxillary growth in patients with decreased vertical dimension is reported to display a tendency toward further forward growth compared to that of patients with increased vertical dimension, given that the maxilla and mandible continue their harmonious growth.[12] It is difficult to determine whether the differences in maxillary growth reflect the true impact of a treatment or natural growth potential of two different face types. Pterygopalatine fossa is an anatomical formation deeply lodged in the central area of the face containing complex vascular and neural structures. Fossa pterygopalatina is a small pyramidal depression located under the apex of the orbit on the lateral side of the skull.[13],[14] Williams et al.[15] evaluated the effect of midline deviation on smile esthetics in different facial types (europrosopic, mesoprosopic, and leptoprosopic), reporting that the facial type has an impact on the perception of midline deviation degree. As a result, in-depth anatomical assessment of these structures before dental procedures and surgical procedures, in particular, ensures the safety of the treatment.

The aim of this study is to evaluate the vertical facial dimensions, fissura pterygomaxillaris, the mandible–maxilla relationship, and the relationship between the position of the maxillary third molars and the vertical facial length on cephalometric and panoramic images.

 Materials and Methods

This study included of panoramic and lateral cephalometric images from 200 asymptomatic patients between the ages of 18 and 30 years with upper impacted wisdom teeth, indication of surgical extraction, and physical status I according to the American Society of Anesthesiologists, who were admitted to İstanbul Aydın University Faculty of Dentistry Orthodontics and Oral, Dental and Maxillofacial Radiology Clinic for treatment between 2015 and 2018. The study included patients with unilaterally and bilaterally impacted teeth with complete bone retention. The teeth were selected based on Archer's impacted wisdom tooth classification [Figure 1].[16] Accordingly, the teeth were selected from Class 3 and Class C groups, namely from those in vertical position and in a Crown-Neck relationship with the second molar.[16] The study conducted on the patients who were admitted to our orthodontic clinic to undergo orthodontic treatment with the permission of Istanbul Aydin University Faculty of Dentistry “Ethics Committee on Non-Interventional Clinical Research-Research Not Involving Pharmaceutics and Medical Devices” (Number: B.30.2AYD.0.00.00-50.06.04/67). Patients under 18 years of age with a systemic disease, temporomandibular joint disorder, or developmental-acquired craniofacial or neuromuscular deformity and a history of orthodontic treatment and facial and dental trauma were not included in the study. The data obtained from the patients who suffered a trauma or injury in the head-and-neck region, with a history of surgical operation on the sinus or skull base, a systemic disorder or genetic disorder, syndrome, or congenital anomalies (craniosynostosis and hemifacial microstomy) presenting in the head-and-neck region, were not included in the study. Volunteers between 18 and 30 years of age with bilateral upper impacted third molars, no local factors leading to impaction of upper third molars, and no loss of the third molar with incomplete root development or adjacent second molar due to any reason were included in the study. “Informed voluntary consent form” and “patient follow-up form” were drawn up for all the patients. All radiographs were taken using the same cephalometry device (Planmeca 2011-05 Proline Pan/Ceph X-ray brand X-ray unit, Helsinki, Finland) with the Frankfurt plane parallel to the ground, teeth in centric occlusion, and lips in resting position. Cephalometric radiographs were evaluated by the same researcher using the NemoCeph NX 9.0 software program (Nemotech, Imaging and Management Solutions, Chatsworth, Madrid, Spain). Skeleton classification was done according to ANB angle, as shown in [Table 1]. The vertical facial length was calculated by measuring the distance between N-ANS, ANS-ME, N-ME, and S-GO values [Figure 2].{Figure 1}{Table 1}{Figure 2}

Statistical analysis

The data were analyzed on SPSS 22.0 (Statistical Package for the Social Sciences, Chicago, Illinois, USA) package program. The ANOVA test was used in the comparison of the parameters. The Bonferroni test was utilized for multiple comparisons. Analysis of the correlation between the variables was made using the Pearson test. Data analysis was assessed using Chi-square, Mann–Whitney U, Wilcoxon, and Kruskal–Wallis tests. t-test was used in gender assessments. The significance level was considered statistically significant for P < 0.05.


The study was conducted on 258 maxillary third molars from 99 female (49.5%) and 101 (50.5%) male patients, with a total of 200. Of the 200 patients included in the study, 58 had bilateral and 142 had unilateral maxillary third molars. Of the 101 male patients, 31 (49.3%) had bilateral and 70 (53.4%) had unilateral maxillary third molars; of the 99 female patients, 27 (46.6%) had bilateral and 72 (50.7%) had unilateral maxillary third molars [Table 2]. Skeletal Class I was identified as 50.3%, skeletal Class II as 42.1%, and skeletal Class II as 7.6% [Table 3].{Table 2}{Table 3}

The evaluation revealed only the S-GO (total posterior facial length) variable to be statistically significant based on molar status (Mann–Whitney U-test). No difference in other variables was observed based on molar status [Table 4]. While ANS-ME and N-ANS variables differed according to gender, no statistical difference was found between the other variables.{Table 4}


Teeth that failed to erupt into the dental ark in time and take their place in normal occlusion and are completely or partially retained in the bone or soft tissue are defined as impacted.[16],[17],[18],[19] Difficulty in wisdom teeth taking their place in the dental arch depends on inadequate space as well as the fact that the dentition and eruption conditions and the distance and direction they have moved during eruption differ from other teeth. The upper wisdom teeth do not fall within the scope of orthodontic theory, and they complete the eruption process with a completely opposite movement. The upper second molar erupts in a downward and forward direction, whereas the upper wisdom teeth can make a triple movement in downward, backward, and outward directions. This complex movement is often delayed in modern humans, and the completion of the normal formation of tuber maxilla causes the upper wisdom tooth to remain impacted. Even if there is sufficient room for the wisdom tooth to erupt, some local and systemic factors adversely affect the eruption of these teeth into the occlusal plane.[20] However, no studies have been conducted on the direct effect of vertical face length on the bilateral or unilateral impact of the upper wisdom teeth or any correlation between them.

Since the investigation in the basic design had been performed according to vertical pattern, 200 patients participating in the study were divided into three groups according to their vertical skeletal development through the joint evaluation of SN-GoMe angle and Jarabak ratio measured in their initial lateral cephalometric radiographs. Cha et al. utilized the SN-GoMe angle when classifying the patient groups according to their vertical dimensions.[21] Pavoni et al., on the other hand, based their classification of the patients with Class III malocclusion according to their vertical develop on the SN-MP angle.[22] Yoshida et al. classified the patients based on the FMA angle,[12] whereas Koh and Chung did so based on the FMA angle and lower facial height.[23] As facial height can be easily affected by development or gender; it has been reported that both the anterior facial heights and the posterior facial heights should be taken into consideration and that it would be optimal to use anterior/posterior facial height ratios in the evaluation of facial patterns.[22] Since SNGoMe angle too is affected by skull base plan, which may vary between individuals, Jarabak ratio is also planned to be included in the criteria. The vertical development patterns of the face are examined in three ways – hyperdivergent (high angle), hypodivergent (low angle), and normodivergent (normal angle) – and these patterns vary depending on various factors during the developmental period. These factors include the development of jaws, dentoalveolar development, eruption of teeth, and the function of the lips and tongue.[12] If the rate of vertical development in condyles is lower than the rate of vertical development in the facial sutures (maxilla) and/or alveolar processes, the mandible rotates clockwise (hyperdivergent growth model). In the opposite case, that is, if the rate of condylar development is higher than the rate of vertical development in the facial sutures (maxilla) and/or alveolar processes, the mandible rotates counterclockwise (hypodivergent growth model). Moreover, if the rate of condylar development is equal to the rate of vertical development in the facial sutures (maxilla) and/or alveolar processes, the mandible follows a normal growth pattern.[24],[25] The hyperdivergent growth model is characterized by decreased posterior/anterior face height ratio, increased lower face height, and mandibular angle, whereas the hypodivergent growth model has direct opposite characteristics.[26],[27] The type and severity of different skeletal patterns are often masked by facial soft tissues. Although the general perception since the late 1950s had been that the softtissue profile would passively follow the hard tissue, later studies indicated that soft tissue showed an independent developmental pattern.[28],[29] Tsunori et al.[30] argued that there was a link between the maxillofacial complex development in vertical and transversal dimensions and increased muscle activity. The literature was reviewed for soft-tissue thicknesses in different vertical direction patterns. Macari and Hanna [31] found that chin soft-tissue measurements were lower in hyperdivergent individuals compared to normal and hypodivergent adults. Celikoglu et al.[32] similarly reported that soft-tissue thicknesses were lower in both male and female high-angle individuals. As a result of the PTM fissure evaluations based on the localizations of patients who were categorized according to gender and presence of wisdom tooth, the number of impacted upper wisdom teeth has been detected to be higher in females compared to males in the majority of cases, and the difference in question was not found to be statistically significant (P > 0.05). This is thought to be caused by one of the factors related to vertical direction. However, it does not appear to be related to PTM fissure. In their study assessing the relationship of 202 lower wisdom teeth with the mandibular canal, Mahasantipiya et al.[33] reported narrowing of the canal in 135 cases (66.8%), stating that, although this may not cause pericoronitis, it could still lead to neurovascular disorders in the region. The literature reviews did not reveal any study on the relationship between the upper wisdom teeth and the PTM fissure. The studies by Mahasantipiya et al.[31] do not establish any relationship between upper wisdom teeth and PTM fissure that is similar to the one with narrowing of the canal, and this gives rise to the thought that it may be caused by upper wisdom teeth among the causes of vertical growth. The study by Ghaeminia et al.[34] reported a close relationship between mandibular wisdom teeth and mandibular canal and a greater risk of complication in impacted wisdom tooth surgery due to the changes in wisdom tooth location and the mandibular canal trace. Considering the close proximity of maxillary impacted wisdom teeth to the PTM, the present study anticipates that, similar to the relationship of mandibular wisdom teeth with mandibular canal shown in the studies by Ghaeminia et al.,[34] the shape of the PTM too may be affected by wisdom teeth. In the present study, evaluations revealed no difference between the PTM widths and lengths and the impacted wisdom teeth and genders. Based on the results of the cephalometric analyses performed in our study, the increase in upper anterior face height and S-GO length measurement in males is thought to be characterized by the increase in maxilla skeletal unit. In their three-dimensional KIKT studies, Costa et al.[35] recorded findings indicating no correlation between the anterior face height and the maxillary posterior vertical alveoli and thereby PTM which is in contradiction with our findings. Rothstein and Yoon-Tarlie,[36] on the other hand, found in their longitudinal study a statistically positive correlation between anterior face heights and maxilla posterior heights of individuals between the ages of 10 and 12 years, which is also consistent with our findings. This is thought to be caused by population differences. Unlike our study, the researchers used lower facial height (ANS-Me) and anterior facial height (N-Me) measurements instead of SN/GoGn angle to identify the vertical pattern. However, these measurements are not sufficiently informative about vertical growth pattern. Increased vertical facial dimension results in transversal narrowing of the dental arcs. This is due to a heightened pressure on the buccal tissue caused by the increased vertical dimension. Personal treatment plan can lead to a wider appearance of the maxillary arc in individuals with a shorter face and a narrower appearance in individuals with a longer face.[35] Vertical growth patterns play an important role in the length of the maxilla and mandible. Jaw length is associated with vertical growth patterns. Individuals with a long face have smaller skeletal sagittal dimensions, whereas individuals with a short face have increased sectional dimensions.[37],[38] Grippaudo et al.[39] reported an increase in upper arc length in high-angle individuals and a decrease in low-angle ones. Our study did not find any difference between genders. In parallel with other studies in the literature, Tuǧsel et al.[40] also make no mention of a difference in the distribution of impacted teeth with regard to gender. In the study carried out by Dural et al.,[41] the incidence of impacted teeth was found to be higher in females than in males, and this was statistically confirmed. Maxillary third molar teeth were most commonly observed in mesioangular and vertical positions, whereas the upper third molar teeth were most commonly seen in vertical position in parallel with the findings of Tuǧsel et al.[40] They reported observing a smaller number of distoangular positions and rarely horizontal positions. Hattab and Alhaija noted that inadequate retromolar space was notably related to tooth impaction and that even in the case of sufficient retromolar space, an impaction rate of 17% was observed nonetheless.[42]


This study demonstrated that there is a difference in the impact of wisdom tooth depending on the anomalies, but these have been found to be statistically insignificant. We believe that studying vertical patterns on larger populations to have a better understanding of their impact on upper wisdom teeth will pave the way for early detection of anomalies.

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Conflicts of interest

There are no conflicts of interest.


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