|Year : 2017 | Volume
| Issue : 1 | Page : 15-21
Mandibular symmetry in participants with a unilateral cleft lip and palate
Ozge Uslu-Akcam1, Ufuk Toygar Memikoglu2, Mehmet Okan Akcam2, Mehmet Birol Ozel3
1 Clinic of Orthodontics, Ministry of Health, Tepebası Oral and Dental Health Hospital, Ankara, Turkey
2 Department of Orthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey
3 Department of Orthodontics, Faculty of Dentistry, Karadeniz Teknik University, Trabzon, Turkey
|Date of Web Publication||2-May-2017|
Clinic of Orthodontics, Ministry of Health, Tepebası Oral and Dental Health Hospital, Kecioren, Ankara
Source of Support: None, Conflict of Interest: None
Context: Facial asymmetry has been reported to be a typical morphological characteristic of unilateral cleft lip and palate (UCLP). Posteroanterior cephalometric radiographs have shown that in addition to an asymmetrically developed nasomaxillary complex, children with UCLP may also have distorted mandibles. Aims: The aim of this retrospective study was to evaluate mandibular symmetry in participants with a complete unilateral left cleft lip and palate (ULCLP) using panoramic radiographs. Subjects and Methods: Pretreatment records of 163 participants (84 ULCLP, 79 Angle Class I without a cleft; mean age: 12.9 ± 3.5 years) were retrieved from the orthodontic department archives. A total of ten anatomic landmarks were marked on panoramic radiographs, and measurements were performed using the PORDIOS software. Statistical Analysis Used: Intra- and inter-group differences were analyzed using Student's t-test. Results: Mandibular right and left ramus, total ramus, condylar, and mandibular molar alveolar heights were significantly shorter in the ULCLP group when compared to controls (P < 0.05 to P< 0.001). In the ULCLP group, mandibular and corpus lengths were shorter on the left side (P < 0.05), whereas in the control group, mandibular and corpus lengths and ramal, condylar, and molar alveolar heights were shorter on the right side when compared to the left side. In addition, ramus/corpus angles were significantly larger in the ULCLP group when compared to the control group (P < 0.001). Conclusions: Mandibular asymmetry exists to varying extents in ULCLP patients and is characterized mainly by smaller cleft-side dimensions. Discrepancies in left-right mandibular dimensions also occur in normal participants.
Keywords: Mandibular dimensions, mandibular symmetry, panoramic radiography, unilateral cleft lip and palate
|How to cite this article:|
Uslu-Akcam O, Memikoglu UT, Akcam MO, Ozel MB. Mandibular symmetry in participants with a unilateral cleft lip and palate. J Cleft Lip Palate Craniofac Anomal 2017;4:15-21
|How to cite this URL:|
Uslu-Akcam O, Memikoglu UT, Akcam MO, Ozel MB. Mandibular symmetry in participants with a unilateral cleft lip and palate. J Cleft Lip Palate Craniofac Anomal [serial online] 2017 [cited 2017 Oct 22];4:15-21. Available from: http://www.jclpca.org/text.asp?2017/4/1/15/205414
| Introduction|| |
Facial symmetry refers to the correspondence in size, shape and location of facial landmarks on opposite sides of the midsagittal plane. While facial asymmetry is a natural phenomenon to the point that no face is perfectly symmetrical, normal asymmetry is not obvious, but severe asymmetry is.
As the focal point of our attention, mandibular morphology, i.e., the structure of the lower third of the face, greatly influences facial esthetics., Moreover, because of its dynamic role in the stomatognathic system, mandibular asymmetry represents not only an esthetic problem but also a functional problem as well. The mandible or mandibular condyle is the primary source of asymmetrical facial development.,,
Facial asymmetry has been reported to be a typical morphological characteristic of unilateral cleft lip and palate (UCLP).,,,, Posteroanterior cephalometric radiographs have shown that in addition to an asymmetrically developed nasomaxillary complex, children with UCLP may also have distorted mandibles.,, The mandibular asymmetry that manifests in UCLP patients develops in parallel with the affected maxilla, suggesting that early evaluation and treatment of both mandibular and nasomaxillary skeletal anomalies is necessary when treating UCLP individuals.,
Studies examining mandibular asymmetry in UCLP patients have reported inconsistent results.,,,,, This may be attributed to differences in study methodologies, radiographic techniques and individual characteristics.
Early diagnosis of mandibular asymmetry is important for interceptive orthodontic and dentofacial orthopedic treatment. In view of the lack of precise information available on the participant, this study aimed to evaluate mandibular asymmetry in children with a complete unilateral left cleft lip and palate (ULCLP) patients and to compare this with a homogeneous Angle Class I control group using panoramic radiographs.
| Subjects and Methods|| |
Diagnostic records of 163 Caucasian participants (mean age: 12.9 ± 3.5 years) were retrieved from the orthodontic department archives. Of these, 79 (41 females, 38 males; mean age: 13.2 ± 3.3 years) were noncleft Angle Class I participants with a normal dentofacial pattern and minimal dental crowding (control group) and 84 (39 females, 45 males; mean age: 12.7 ± 3.7 years) were ULCLP patients [Figure 1]. For ULCLP, all clefts were on the same side (left). Right side clefts, bilateral/isolated clefts were excluded from the study. Posterior crossbite generally existed on the cleft side to various extents. All ULCLP patients had surgical treatment to close their upper lip and cleft before age 3 and were in mixed/permanent dentition. None of the participants had any syndromes or systemic diseases, extraction of a permanent tooth, prosthodontic/orthodontic treatment, or trauma to any tooth before the initiation of orthodontic treatment. Moreover, none of the participants in ULCLP and Class I groups had significant facial asymmetry. Ethical approval had been obtained before the start of the study.
The following landmarks and reference planes were drawn on panoramic radiographs [Figure 2]: (1) Condylion, (2) condylion', (3) ramus-upper, (4) mandibular notch, (5) projection point of condylion on the mandibular notch plane (MNP), (6) ramus-lower, (7) gonion, (8) lower molar - i.e., the most superior/mesial point of the lower first molar crown, (9) projection point of lower molar on the corpus tangent plane (CTP), and (10) menton; ramus tangent plane (RTP): drawn through the most lateral points of the condyle and ramus (landmarks 3 and 6, respectively); CTP: drawn through the most lateral points of the mandibular corpus; condylar plane (CP): drawn through the condylion and perpendicular to the RTP, with the point of intersection with the RTP marked as the condylion'; and MNP: drawn parallel to the CP and passing through the lowest point of the mandibular notch.
Using these landmarks and reference planes, the following dimensions were measured:
Condylar height: Distance between Landmark 1 and the projection point of Landmark 1 on the MNP.
Condylar height”: Distance between condylion' and lower ramus.
Ramus height: Distance between upper and lower ramus.
Ramal height: Distance between condylion and lower ramus.
Upper condylar height: Distance between condylion' and upper ramus.
Mandibular length: Distance between the condylion and menton.
Corpus length: Distance between the gonion and menton.
R/C angle: Angle between the line drawn between the condylion and gonion and the line drawn between the gonion and menton.
R/C tangent angle: Angle between the RTP and CTP.
Lower molar alveolar height: Distance between lower molar and projection point of lower molar on the CTP.
Angular and linear measurements were recorded separately for the right and left sides using the PORDIOS software (Purpose on Request Digitizer Input-Output system, Institute of Orthodontic Computer Sciences, Denmark). All films were exposed by the same technician using the same device (Siemens, P10E, Palomex Instrumentarium, Finland) and the same standardized method, and all measurements were made by the same author and repeated after an interval of at least 3 weeks.
Statistical analysis was performed using the software SPSS version 11.0 (SPSS, Inc., Chicago, IL, USA). Repeatability coefficients for each parameter were calculated to test the reliability of measurements. Student's t-test was used to assess differences between groups and within groups between right and left sides.
| Results|| |
Repeatability coefficients ranged from 0.8197 to 0.9986, indicating reliability of measurement [Table 1].
Right and left ramus heights, right and left total ramal heights as well as right and left condylar heights” were significantly smaller in the ULCLP group (P < 0.01, P< 0.001) [Table 2].
Left mandibular and corpus lengths were also significantly smaller in the ULCLP group when compared to the control group (P < 0.05). Right and left ramus/corpus angles (P < 0.001) and R/C tangent (P < 0.05) angles were significantly larger in the ULCLP group, whereas right and left lower molar alveolar heights were significantly shorter (P < 0.01) in the ULCLP group.
In the ULCLP group, condylar height and mandibular and corpus lengths were significantly smaller on the left side when compared to the right side (P < 0.05, P< 0.001) [Table 3]. Statistically significant differences (P < 0.05, P< 0.01) between left- and right-side linear and angular measurements were also found in the control group, with mandibular and corpus lengths significantly larger on the right side compared to the left side and ramus/corpus and R/C tangent angles significantly larger on the left side compared to the right side (P < 0.01).
| Discussion|| |
Panoramic radiographs have been widely used in the study of mandibular asymmetry., Kambylafkas et al. reported that panoramic radiographs can be used to evaluate vertical posterior mandibular asymmetries, and Akcam et al. showed that they can provide information on the vertical dimensions of craniofacial structures. Panoramic radiographs are noninvasive, have a favorable cost–benefit ratio and require relatively low doses of radiation.,, Disadvantages include the possibility that the lateral margin of the glenoid fossa and zygomatic arch root may mask the condylar region. This study utilized panoramic radiographs for their ability to provide a bilateral image of the mandible, in light of the advantages mentioned above as well as the fact that ethical considerations precluded the use of cone beam computed tomography (CBCT) or other three-dimensional (3D) imaging techniques, particularly in growing participants.
In a study performed using facial laser scanning, Djordjevic et al. found that the amount of 3D facial asymmetry was higher in a group of unilateral cleft lip patients with or without cleft palate when compared to normal participants. Sezgin et al. reported no significant differences between males and females in terms of the effects of different types of occlusion on mandibular asymmetry. Moreover, Kurt et al. found no significant gender differences in mandibular asymmetry among CLP patients. Therefore, the current study did not include gender among the parameters evaluated.
Numerous studies have used various types of computed tomography techniques to evaluate facial asymmetry in CLP patients.,,,, In a study of CBCT images, Celikoglu et al. reported ramal height and ramal + condylar height measurements to be significantly lower on the cleft side in UCLP patients. Another CBCT study by Kim et al. reported a mild chin deviation toward the cleft side in UCLP patients as well as positive correlations between chin deviation and temporomandibular fossa inclination, mandibular body and ramus lengths, and condylar volume.
Interestingly, this study found a statistically significant asymmetry of the right and left condylar heights in the control group [Table 3]. This contrasts with Kiki et al., who reported no statistically significant differences between right and left condylar or ramal heights in a control group with normal occlusion although the “condylar asymmetry index” used by the authors did point out a slight asymmetry between the right and left condyles of controls. Differences in findings between studies suggest the need for a more precise system of measurement to evaluate both condylar and mandibular asymmetry.
Kiki et al. also reported greater differences between right and left condylar and ramus heights in ULCLP patients when compared to controls; however, the differences between the groups were not statistically significant. The current study found the height of the left condyle to be statistically smaller in comparison to the right condyle in the ULCLP group [Table 3]. This could be related to the abnormal occlusal relationship stemming from the unilateral constriction of the maxillary dental arch, which could in turn affect mandibular movement and thus condylar development. In other words, reduced function could result in underdevelopment of the cleft-side condyle. Inui et al. hypothesized that occlusal problems during the growth period could cause continuous condylar displacement into the glenoid fossa, resulting in differential growth of the left and right condyles. The condyle has been reported to be one of the structures most sensitive to occlusal changes. Considering that the condyle is generally affected by transverse anomalies in growing individuals, a posterior crossbite could be a factor in the development of condylar asymmetry in ULCLP patients.
Malocclusions in general and transverse anomalies in particular have been shown to have a marked effect on mandibular condyle morphology.,, Kusayama et al. reported a high correlation between transverse dental anomalies and skeletal asymmetry, and a study by Solberg et al. conducted with autopsy material from young adults found variations in condylar form to be associated with malocclusions such as crossbite. Asymmetrical constriction of the palatal vault has also been suggested as a cause of condylar asymmetry.
Jena et al. reported significant mandible asymmetries in participants with UCLP and near-normal sagittal maxillary growth, while the mandible was nearly symmetrical among UCLP patients with very severe sagittal maxillary growth hypoplasia.
Liukkonen et al. reported statistically significant differences between right and left condylar heights at age 7 years, between ramus heights at ages 7 and 16, and between condylar and ramus heights at age 16 in healthy children. In line with these findings, the current study observed a statistically significant difference between right and left condylar and ramus heights in the control group. However, as Liukkonen et al. emphasized, given Melnik's finding that asymmetry is present at all ages, it is possible that mandibular asymmetry may not only develop but may also diminish during the growth period of healthy participants so that even when condylar/ramal asymmetry is clearly observable from orthopantomograms, the decision as to whether or not to initiate treatment because of asymmetry should be given careful consideration.
Abuhijleh et al. found the cranial base, maxilla, and mandible in UCLP patients to be affected on the sagittal plane during all growth periods, whereas horizontal asymmetries were mainly detected before and during puberty; moreover, vertical asymmetries were less severe, and there was no distinctive mandibular asymmetry when compared to a Class I group.
Abad-Santamaría et al. reported condylar asymmetry in unilateral posterior crossbite, UCLP, and normal occlusion groups based on the fact that condylar asymmetry indexes were higher than other asymmetry indexes in each of these groups at the 3% threshold. No statistically significant differences were found among the three study groups for any of the asymmetry indexes.
In addition to the dimensional measurements used in the current study, Kyrkanides and Richter reported that the degree of antegonial notching apparent on panoramic radiographs can be used as an early indicator of potential mandibular and lower facial asymmetry in individuals with UCLP.
In contrast to the findings of the current study, studies by Laspos et al. that used posteroanterior and oblique cephalometric radiographs to examine mandibular asymmetry in UCLP patients found no significant differences in mandibular asymmetry between UCLP patients and controls., This may be related to the use of a heterogeneous control group that included participants with various types of malocclusion, whereas the control group in the current study was homogeneous and comprised Angle Class I participants with harmonious craniofacial patterns. It should also be noted that Laspos et al. concluded that mandibular asymmetry was not the major contributing factor in the lower facial asymmetry noted in UCLP patients.,
In line with a study by Smahel and Brejcha, the present study reported a shorter mandibular body and ramus in UCLP patients when compared to controls. Moreover, while the present study found dimensions in ULCLP patients in general to be smaller than those of controls, gonial angle was statistically larger in the ULCLP group when compared to controls. Jain and Krogman also noted significantly greater gonial height among UCLP patients when compared to controls. Interestingly, in the present study, left and right R/C tangent angles in the ULCLP group were similar, whereas the left side was statistically larger than the right side in controls.
The border between “normal” and “abnormal” asymmetry cannot be easily defined. However, despite the fact that no absolute standard exists by which a judgment of abnormality can be made, clinicians can easily identify mandibular asymmetry by measuring bilateral dimensions on panoramic radiographs, and treatment can be appropriately timed to prevent asymmetries from increasing.
| Conclusions|| |
- Right-side mandibular dimensions are generally larger than left-side dimensions in ULCLP patients
- Mandibular dimensions of ULCLP patients are smaller than controls, indicating that ULCLP not only affects the maxilla but may also indirectly affect mandibular dimensions
- Discrepancies in left-right mandibular dimensions occur in normal participants as well as in ULCLP patients
- Further prospective studies should be planned to confirm and improve the results found in the current study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]