Abstract
Background
Patients operated for cleft deformities may have zygomatic hypoplasia secondary to impaired growth of the maxilla. This has, however, not been evaluated in the past.
Subjects and Methods
This study was a prospective, case–control study. This included 32 patients, aged between 19 and 25 years, who were divided into cleft and non-cleft groups. The cleft group was further divided into unilateral clefts, bilateral clefts and isolated palatal clefts. In both groups, the zygoma was assessed and compared on both sides clinically using indirect photogrammetry and radiographically using 3D CT. The results were analyzed statistically using the unpaired t test.
Results
There was a significant difference in the zygomatic projection on cleft and non-cleft sides in the unilateral cleft group. There was no significant difference in the zygomatic projection of both sides in the other subgroups and the control group.
Conclusion
The present study shows that there is a global effect of palato-alveolar cleft repair on the midfacial skeleton. Further studies are required to correlate the impact of age, gender and the technique of palato-alveolar cleft repair with the quantum of malar hypoplasia.
Keywords: Zygomatic hypoplasia, Cleft lip and palate, Palatoplasty, Midface hypoplasia
Introduction
The management of patients with cleft lip and palate has evolved greatly over the years. Despite this, the surgical management of these conditions is still associated with secondary deformities. One such classic deformity, seen after repair of cleft palate and alveolus, is midface hypoplasia, which is usually discussed in the literature in terms of maxillary retrognathism. However, the midface also consists of the zygomatic complex, of which the malar eminence is the key unit. This unit forms a syndesmosis with the maxilla at the zygomatico-maxillary suture. We hypothesize that, being in close anatomical proximity to the maxilla, the malar eminence may take up the repercussions of the scarred palato-maxillary muco-periosteum, which is currently considered the primary etiologic factor for cleft maxillary hypoplasia. Apart from this, the body of the zygoma develops from the first pharyngeal arch, which may genetically be programmed for a hypoplastic phenotype in patients with non-syndromic cleft lip and palate similar to the cleft maxillae. Therefore, it may be worth assessing the impact of the palato-alveolar cleft repair procedures on the growth of the zygoma. Zygomatic hypoplasia in cleft patients has seldom been discussed in the literature. The aim of this paper was to assess the incidence of zygomatic hypoplasia in patients operated for palato-alveolar clefts and discuss the factors that predispose to the development of zygomatic hypoplasia in these patients.
Methods
The study was a prospective, case–control pilot study, which was approved by the institutional review board, SRM University. The study group (Group A) included 17 non-syndromic cleft patients between 19 and 25 years of age, who reported to our center for the correction of secondary cleft deformities. Informed consent was obtained from all patients for photogrammetry and investigations. This group was divided into various subgroups based on the type of cleft deformity that they had. Cleft patients who were associated with syndromes were excluded from the study. The control group (Group B) included age-matched, sex-matched healthy individuals from the same regional location who reported for the management of various dental issues. Neither the study group nor the control group had any history/ongoing orthodontic treatment. Both groups of patients underwent clinical, photographic and radiographic examination to assess the zygoma bilaterally. Occlusal relationships were recorded in all the patients, in order to correlate the zygomatic hypoplasia with the dentoalveolar maxillary hypoplasia.
Photographic Evaluation
Photographs were taken using Nikon D3200 24.2 megapixel DSLR camera with 18- to 55-mm lens and inbuilt grid pattern from a distance of 30 cms (1 foot). The patients were made to stand in normal head position (NHP) with the Frankfort’s horizontal plane and interpupillary line parallel to the floor. Submental photographs were taken from the chin region with the patient’s head tilted to maximum neck extension from the same distance. Facial landmarks of trichion–pogonion distance and interpupillary distance were measured and transferred onto the photographs to facilitate standardization prior to photogrammetry [1]. Indirect photogrammetry was performed in all the patients to assess the quantum of zygomatic hypoplasia.
Technique of Indirect Photogrammetric Evaluation
Indirect photogrammetry was performed similar to the methods described by Nagy et al. [1], which does not use standard facial landmarks for determining the midline. Facial height (trichion–menton distance) and interpupillary distance were used for standardization of the photographs. The bipupillary line, which was constructed by joining the inferior points of both the pupils, was taken as the horizontal reference line. A perpendicular dropped from the midpoint of this line was taken as the vertical reference line [2]. The point used for lateral reference was the zygion point, which corresponds to the lateral and the most prominent point on the malar eminence at the level of the infra orbital rim [3, 4]. The distance between the midline and the zygion point was then measured on both sides of the face (Figs. 1, 2).
Fig. 1.
Frontal photograph showing the indirect photogrammetry landmarks
Fig. 2.
Submental picture showing zygomatic hypoplasia
CT Evaluation
A computed tomogram with 3D reconstruction was performed in both groups of patients, using Siemens Somatom 64-slice CT machine. One millimeter sections were generated that were used for 3D reconstruction. DICOM software (Digital Imaging and Communication in Medicine) was used for the volumetric assessment bilaterally. The following were the landmarks that we used for volumetric evaluation:
Superiorly Fronto-zygomatic suture
Posterior Plane passing through the beginning of the inferior orbital fissure
Medially Zygomatico-Maxillary suture
Laterally Plane passing through zygion point in the frontal plane
Inferiorly Plane passing through the inferior margin of the zygomatic buttress.
Statistical analysis was performed using SPSS software, which utilized the unpaired t test to determine significance. A p value of < 0.05 was taken as significant.
Results
A total of 32 patients were enrolled in the study. Of these, 17 patients belonged to the study group, of which 13 were male and four were female (Group A). Fifteen patients belonged to the control group, of which 11 were male and four were female (Group B). Based on the type of cleft deformity, patients in the study group were divided into three categories, namely those operated for unilateral cleft lip and palate (Table 1) (Group A1, 11 patients; 64%), those operated for bilateral cleft lip and palate (Table 2) (Group A2, five patients; 29%) and those operated for isolated cleft palate (Table 3) (Group A3, one patient; 5%).
Table 1.
Indirect photogrammetric evaluation and occlusal relation in Group A1
| Patient initials | Cleft t side | IPD | Mid-IPD to zygion—right side | Mid-IPD to zygion—left side | Discrepancy between right and left sides | Anterior dental relation | Posterior occlusal relation |
|---|---|---|---|---|---|---|---|
| AM | Left CLAP | 60 | 62 | 57 (left) | 5 | − 2 mm | Left crossbite with Class III molar relation |
| Sp | Left CLAP | 58 | 56 | 52 | 4 | End-on anterior relation | Left crossbite in relaion to premolar segment with Class III molar relation |
| Na | Left CLAP | 58 | 58 | 54 | 4 | − 3 mm | Left crossbite in relaion to premolar segment with Class III molar relation |
| She | Right CLAP | 60 | 61 | 55 | 7 | End-on anterior relation | End-on molar relation with no crossbite |
| Pu | LT CLAP | 58 | 59 | 54 | 5 | End-on anterior relation | End-on molar relation with no crossbite |
| Ga | Left CLAP | 60 | 59 | 59 | 0 | + 2 mm | Crossbite in relaion to left premolar segment and end-on molar relation of left side |
| MA | Right C LAP | 60 | 56 | 62 | 6 | End-on incisor relation | Crossbite right in relaion to premolar segment and end-on molar relation of right side |
| UP | Right CLAP | 62 | 55 | 61 | 6 | − 4 mm | Bilateral crossbite with class III molar relation |
| AM | Right CLAP | 60 | 57 | 59 | 2 | − 3 mm | Bilateral crossbite with Class III molar relation |
| AG | Right CLAP | 58 | 54 | 59 | 5 | End-on anterior relation | Class I molar relation bilaterally |
| Bg | Left CLAP | 58 | 58 | 58 | 0 | − 4 mm | Bilateral crossbite with Class III molar relation |
Table 2.
Indirect photogrammetric evaluation and occlusal relation in Group A2
| Patient initials | Diagnosis | IPD | Distance between mid-pupillary line and zygion right side | Distance between mid-pupillary line to zygion left side | Discrepancy between the right and left sides | Anterior occlusal relation | Posterior occlusal relation |
|---|---|---|---|---|---|---|---|
| BK | B/l | 62 | 62 | 62 | Equal | Positive overjet | Class I relation with no crossbite |
| Ved | B/L | 62 | 57 | 61 | 4 | Positive overjet | Class I molar relation with crossbite irt premolar segment |
| SN | Bilateral CLAP | 62 | 61 | 58 | 3 | Positive overjet | Class I molar relation with no crossbite |
| RV | B/l CLAP | 58 | 56 | 56 | Equal | Positive overjet | Class I molar relation with crossbite irt premolar segment |
| Pr | Bilateral | 58 | 57 | 55 | 2 | Positive overjet | Class I molar relation with crossbite irt premolar segment |
Table 3.
Indirect photogrammetric evaluation and occlusal relation in Group A3
| SN | Incomplete palate | 61 | 61 | 58 | 3 | Positive overjet | Class I molar relation bilaterally |
Occlusal Relation
Clinical dental examination revealed that eight out of 11 patients in Group A1 (81%) had posterior crossbite in relation to the cleft segment with end-on relation of the anterior teeth. The remaining three patients had negative overjet of 3–5 mm with complete collapse and crossbite of the cleft segment posteriors (Table 1). In Group A2, all the patients had positive anterior overjet. However, three out of five patients (60%) had bilateral posterior crossbite, while the other two had Class I molar relation (Table 2). The single patient in Group A3 had normal Class 1 molar relations with a positive overjet (Table 3). The occlusal relationships of the study group reflected that some degree of midface hypoplasia was definitely present in most patients.
All the patients in Group B had positive overjet and Class I molar relation (Table 4).
Table 4.
Indirect photogrammetric evaluation and occlusal relation in Group B
| SP | 58 | 61 | 59 | Positive overjet with Class I molar relation |
| JD | 62 | 59 | 59 | Positive overjet with Class I molar relation |
| SP | 60 | 59 | 58 | Positive overjet with Class I molar relation |
| PO | 58 | 57 | 57 | Positive overjet with Class I molar relation |
| VV | 64 | 58 | 58 | Positive overjet with Class I molar relation |
| SS | 59 | 60 | 60 | Positive overjet with Class I molar relation |
| dk | 58 | 62 | 62 | Positive overjet with Class I molar relation |
| Dh | 58 | 62 | 62 | Positive overjet with Class I molar relation |
| RK | 64 | 58 | 58 | Positive overjet with Class I molar relation |
| SS | 59 | 60 | 60 | Positive overjet with Class I molar relation |
| VK | 58 | 61 | 59 | Positive overjet with Class I molar relation |
| JG | 62 | 59 | 59 | Positive overjet with Class I molar relation |
| JD | 60 | 59 | 58 | Positive overjet with Class I molar relation |
| GP | 58 | 57 | 57 | Positive overjet with Class I molar relation |
| Sk | 64 | 58 | 58 | Positive overjet with Class I molar relation |
Indirect Photogrammetry Results
The interpupillary distance, as measured by indirect photogrammetry, was found to be between 58 and 62 mm in both the study and control groups. This was not expected to be significantly different, as all the study cases were non-syndromic. The mean IPD in the study group was 59.56 mm and was 59.86 mm in the control group (Table 5). Since this was not statistically different (p < 0.05), the IPD line was used as a standard for other measurements, and the midpoint of the IPD line was used as the midpoint of the face.
Table 5.
Statistical evaluation: Comparison of interpupillary distance between the study and control groups
| Mean IPD | T value | P value | |
|---|---|---|---|
| Group A | 59.56 | − 0.35 | 0.36 |
| Group B | 59.86 |
The midpoint–zygion (M–Z distance) distance was found to be different in different groups. In the unilateral cleft group (Group A1), nine out of 11 patients (81%) had deficiency of the M–Z distance on the cleft side as compared to the normal side (Fig. 3). The mean deficit recorded was 5 mm (range 2–7 mm) (Table 1). Statistical analysis revealed a significant difference between the cleft and non-cleft sides in Group A1 (p < 0.05, Table 6).
Fig. 3.
Zygomatic hypoplasia in unilateral cleft lip and palate patient
Table 6.
Statistical evaluation: Comparison of midline–zygion distance on the cleft and non-cleft sides in patients with unilateral clefts
| Mean M–Z | T value | P value | |
|---|---|---|---|
| Group A1 (cleft side) | 55.55 | 4.66 | 0.000076 |
| Group A1 (non-cleft side) | 59.45 |
In the group with bilateral clefts (Group A2), a similar deficit was noticed, with three out of five patients (60%) having asymmetry. The mean deficit was 3 mm (2–5 mm) (Table 2), and the hypoplasia was located in the right side in one patient and the left side in two patients. The single patient with isolated cleft palate (Group A3) also had a deficit of 3 mm on the left side as compared to the right (Fig. 4, Table 3). Taken together, these results were not statistically significant (p > 0.05, Table 7). However, it was noted clinically that there was complete collapse of the premolar segment in three patients of Group A2, corresponding to the side of malar hypoplasia, leading to an extreme degree of crossbite.
Fig. 4.
Zygomatic hypoplasia in incomplete cleft palate patient
Table 7.
Statistical evaluation: Comparison of midline–zygion distance on both sides in patients with bilateral clefts and isolated cleft palate
| Mean M–Z | T value | P value | |
|---|---|---|---|
| Group A2, A3 (right) | 59.67 | 1.41 | 0.095 |
| Group A2, A3 (left) | 57.67 |
The control group (Group B) also had minor differences between the right and left sides; however, the maximum difference was 2 mm and these results were not found to be statistically significant (Table 8).
Table 8.
Statistical evaluation: Comparison of midline–zygion distance on both sides in the control group
| Mean M–Z | T value | P value | |
|---|---|---|---|
| Group B (right) | 59.43 | 0.48 | 0.32 |
| Group B (left) | 59 |
We also compared the midline–zygion values of the cleft groups and control groups. There was a statistically significant difference in the mean value of both groups (p < 0.05, Table 9).
Table 9.
Statistical evaluation: Comparison of midline–zygion distance between cleft patients and normal controls
| Mean M–Z | T value | P value | |
|---|---|---|---|
| Group A1, A2 (cleft side) | 57 | − 2.74 | 0.0049 |
| Group B | 59.21 |
The CT evaluation revealed that the patients in Group A1 had malar hypoplasia with a mean linear (midline–zygion as seen on basal view of 3D reconstruction) discrepancy of 5 mm (4–6 mm). This was secondary to the reduced projection of the malar eminence (Figs. 5, 6). The volume of the zygoma was found to be equal on both the sides (range 5436–6543 mm). This was similar to the volume seen in the non-cleft group (5495–6345 mm3) [3]. The zygomatic arch of the affected side also showed lesser transverse projection from the root to the zygomatico-temporal suture when assessed visually, as compared to the unaffected side in all the patients.
Fig. 5.
Frontal 3D CT showing the zygomatic hypoplasia with transverse maxillary hypoplasia
Fig. 6.
Submental 3D CT image showing reduced projection of the zygomatic arch at the root with zygomatic hypoplasia of the left side
Discussion
Facial clefting is a progressive, complex congenital malformation that presents with a multitude of problems in the stomatognathic system. Though the primary correction of cleft lip and palate is surgically completed in early childhood, the repercussions of these procedures are seen throughout the growth phase, which warrants protracted management protocols. Midface hypoplasia with mandibular prognathism is the classic facial profile in non-syndromic adult patients with cleft lip and palate. This has been attributed to the intrinsic deficiency in the growth potency of the maxilla, along with iatrogenically induced growth disturbances secondary to the repair of palato-alveolar clefts [5]. The malar eminence forms the cornerstone of facial esthetics. We have noticed that this eminence also takes the repercussive whiplash effect of retarded maxillary growth and presents as zygomatic hypoplasia. Not much has been reported on zygomatic hypoplasia in cleft patients; however, one study has reported an average of 28–30% incidence of zygomatic hypoplasia in operated non-syndromic CLAP patients [6]. To our knowledge, no studies till date have described the variability that can be associated with different types of facial clefts, and the present study is the first of its kind to assess the incidence of the zygomatic hypoplasia in adult patients with different patterns of facial clefts.
It has already been shown in the literature that the transverse maxillary hypoplasia seen in cleft patients is secondary to the arrested appositional growth and remodeling of the dentoalveolar component of the maxilla. This occurs due to the biphasic vascular insult caused by the labio-palatal cleft repair along with the loss of the osteogenic cambium layer of alveolar maxilla [7]. Alveolar bone grafting [8] also synergizes the growth retardation effect, as the buccal transposition flap used for the labial closure of cleft alveolus denudes the cambium layer in the region of the zygomatico-maxillary suture. This leads to healing by secondary intention and further retardation of the appositional growth at this suture [8]. These multiple areas of scarring and fibrosis negate the growth at the circum-maxillary sutures leading to maxillary hypoplasia and associated decreased projection of the zygoma [5].
Correlations drawn between the indirect photogrammetric findings and the dentoalveolar maxilla–mandibular relationship support the hypothesis that the zygomatic hypoplasia in non-syndromic CLAP patients is secondary to the lack of projection of the zygoma, which in turn is due to the hypoplastic transverse growth pattern of the affected maxilla. The CT findings also support this fact as the volume of the zygoma was equal bilaterally in all the patients of the study group with reduced projection of the zygoma on the affected side.
The present study supports the hypothesis that palato-alveolar scarring is a primary cause for the reduced projection of the malar eminence of the affected side. FEM studies on the transverse maxillary expansion in operated patients with cleft lip and palate have shown that the primary palate (in an operated incomplete cleft palate) and the zygomatico-maxillary buttress (in an operated complete cleft palate) offer maximum resistance to the midfacial growth in transverse dimension [9]. These studies also validate the fact that malar hypoplasia could be a repercussion of palato-alveolar repair.
The role of interceptive orthodontics in preventing transverse maxillary and zygomatic hypoplasia needs to be analyzed. Interceptive orthodontics, particularly palatal expansion, has shown to aid in transverse expansion of the maxilla and opens the circum-maxillary sutures [10]. Therefore, it may be possible that maxillary expansion prior to alveolar bone grafting may aid in improving the projection of the malar eminence, as the zygomatico-maxillary suture would remain intact. However, at present, there is no literature evidence on the improvement in the transverse projection of the zygoma by palatal expansion. Studies have shown that the greater quantum of expansion is restricted to the para-nasal skeleton after palatal expansion [11]. This makes surgical interventions in the form of malar osteotomy or malar augmentation essential to improve the zygomatic projection, which would in turn enhance the facial esthetics.
The present study describes the global effect of palato-alveolar cleft repair on the midfacial skeleton and discusses the probable interceptive and corrective management modalities that can enhance the facial symmetry in patients with cleft lip and palate. However, we could not correlate the impact of age, gender and the technique of palato-alveolar cleft repair with the quantum of malar hypoplasia. A prospective, long-term evaluation on a large volume of patients, with the above factors in mind, is essential to assess the impact of palato-alveolar repair procedures on the craniofacial skeleton.
Compliance with Ethical Standards
Conflict of interest
All authors declare that they have no conflict of interest.
Contributor Information
Pendem Sneha, Email: drsneha_p@yahoo.com.
Poornima Ravi, Email: drpoornimaravi@gmail.com.
References
- 1.Krisztian N, Mommaerts MY. Analysis of cleft lip nose in submental vertical view, part I—reliability of new measurement instrument. J Cranio Maxillofac Surg. 2007;35:265–277. doi: 10.1016/j.jcms.2007.04.010. [DOI] [PubMed] [Google Scholar]
- 2.Mommarts MY, Krisztian N. Analysis of cleft lip nose in Submental vertical view, part II: Which is the most important deformity? J Cranio Maxillofac Surg. 2008;36:315–320. doi: 10.1016/j.jcms.2008.01.004. [DOI] [PubMed] [Google Scholar]
- 3.Sadacharan CM, Sikandar R, Kantawala M, Cherian J, et al. Facial analysis of Indian Americans—a direct anthropometric study: international. J Appl Res. 2015;1(12):05–10. [Google Scholar]
- 4.Earcan I, Ozdemir ST, Etoz A, Sigirli D, et al. Facial asymmetry in young healthy subjects evaluated by statistical shape analysis. J Anat. 2008;213:663–669. doi: 10.1111/j.1469-7580.2008.01002.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Liao YF, Mars M. Long term effects of palate repair on craniofacial morphology in patients with unilateral Cleft lip and palate. Cleft Palate Craniofac J. 2005;42(6):594–600. doi: 10.1597/04-077r.1. [DOI] [PubMed] [Google Scholar]
- 6.Da Silva Filho OG, De Rosa LAA, De Lauris RCMC. Influence of cleft palate and palatoplasty on the face. J Appl Oral Sci. 2007;15(3):199–208. doi: 10.1590/S1678-77572007000300009. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Carstens MH. Sequential Cleft management with sliding sulcus technique and alveolar extension palatoplasty. J Craniofac Surg. 1999;10(6):503–515. doi: 10.1097/00001665-199911000-00010. [DOI] [PubMed] [Google Scholar]
- 8.Berkowitz S (2005) Effect of surgery on maxillary growth: Cleft lip and palate—diagnosis and management, 2nd edn. Springer, South Miami, pp 324–326
- 9.Gautam P, Zhao L, Patel P. Determining the osteotomy pattern in surgically assisted rapid maxillary expansion in unilateral palatal cleft: a finite element model approach. Angle Orthod. 2011;81:410–419. doi: 10.2319/070110-369.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Leonardi R, Sicurezza E, Cutrere A, et al. Early post treatment changes of circum maxillary sutures in young patients treated by rapid maxillary expansion. Angle Orthod. 2001;81(1):36–41. doi: 10.2319/050910-250.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Bazargani F, Feldmann I, Bondemark L. Three dimensional analysis of effects of rapid maxillary expansion on facial sutures and bones: a systematic review. Angle Orthod. 2013;83(6):1073–1082. doi: 10.2319/020413-103.1. [DOI] [PMC free article] [PubMed] [Google Scholar]