|Year : 2015 | Volume
| Issue : 1 | Page : 17-20
Postdistraction stability of hypoplastic maxilla in unilateral cleft lip and palate treated using rigid external distraction device: An audit
Prasanna Kumar1, NK Sahoo1, Sanjeev Datana2, ID Roy1
1 Department of Dental Surgery, Armed Forces Medical College, Pune, Maharashtra, India
2 Department of Orthodontics, Army Dental Centre (R and R), Delhi Cantt., New Delhi, India
|Date of Web Publication||8-Apr-2015|
Dr. Prasanna Kumar
Department of Dental Surgery, Armed Forces Medical College, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
Introduction: Maxillary hypoplasia resulting in skeletal class III malocclusion is common among patients with cleft lip and palate. Large anteroposterior discrepancies and surgical scaring often leads to unpredictable stability of maxillary advancement with Le Fort I osteotomy and is known for a high degree of relapse. The aim of this retrospective study was to evaluate the postdisraction stability after 1-year of maxillary advancement done with rigid external distraction (RED) device in patients with unilateral cleft lip and palate. Materials and Methods: Records of 11 cases treated with RED device used for distraction of maxilla in cleft lip and palate cases were assessed. Lateral cephalograms selected were taken at the end of presurgical (T1), immediate postdistraction (T2) and 1-year postdistraction (T3). Five angular measurements and nine linear measurements were used to assess the position of maxilla in all three planes. P values were obtained for repeated measurement by analysis of variance with Bonferroni's correction for multiple comparisons. Normality was tested using Shapiro-Wilk's test. Results: The average 1-year postdistraction measurements (T3) did not differ significantly compared to the corresponding average postdistraction measurements (T2) (P > 0.05). Conclusion: Midface distraction with RED device provides a significant structural improvement for patients with cleft lip and palate. There was marked an improvement in dentofacial structures and results were stable during the retention phase.
Keywords: Distraction osteogenesis, maxillary hypoplasia, rigid external distraction device, unilateral cleft lip and palate
|How to cite this article:|
Kumar P, Sahoo N K, Datana S, Roy I D. Postdistraction stability of hypoplastic maxilla in unilateral cleft lip and palate treated using rigid external distraction device: An audit. J Dent Res Rev 2015;2:17-20
|How to cite this URL:|
Kumar P, Sahoo N K, Datana S, Roy I D. Postdistraction stability of hypoplastic maxilla in unilateral cleft lip and palate treated using rigid external distraction device: An audit. J Dent Res Rev [serial online] 2015 [cited 2019 Nov 18];2:17-20. Available from: http://www.jdrr.org/text.asp?2015/2/1/17/154639
| Introduction|| |
Skeletal class III malocclusion due to maxillary hypoplasia is common among patient with cleft lip and palate. This situation is in 25% of the cases of cleft lip and palate.  Maxillary advancement with or without mandibular setback is one of the basic protocol for correction of midface hypoplasia. As surgical scar is the main cause of relapse of maxillary correction in cleft lip and palate cases, stabilization of advancement is one of the prime factors for the success of the treated cases. Conventional Le Fort I surgery have a high relapse rate of 4-40% and thus it has become an unpredictable surgical option for advancement of maxilla (8 mm or more) in patients with maxillary hypoplasia secondary to CLP. 
Midface advancement as described by Polley and Figueroa  advocates distraction osteogenesis (DO) principles to advance the hypoplastic maxilla especially in patients with cleft lip and palate. The aim of this retrospective study is to find out the postdistraction stability after 1-year in maxillary advancement done with rigid external distraction (RED) device in patients with unilateral cleft lip and palate (UCLP) treated over the period of 4 years in a tertiary care dental institute.
| Materials and Methods|| |
This retrospective study consisted of records of patients with UCLP treated between March 2009 and March 2013 in a tertiary care dental institute with RED device for maxillary advancement.
The inclusion criteria's were
- Patients with UCLP
- Skeletal class III relation
- Negative overjet of 6 mm or more
- Minimum 1-year postdistraction follow-up.
Exclusion criteria's were
- Any syndromic cases
- Any systemic illness
- Previous history of orthognathic surgery or DO.
Based on the inclusion/exclusion criteria's, 11 patients (8 males and 3 females) treated with RED device for distraction of maxilla in UCLP was selected. The age group was between 14 and 20 years with a mean of 16 ± 0.76. Lateral cephalograms of selected patients were used for this study to confirm the postdistraction stability of the DO with RED device. These cephalograms chosen were presurgical or predistraction (T1), immediate postdistraction (T2) and 1-year postdistraction (T3) [Figure 1].
All the patients had undergone the presurgical orthodontics, which consisted of leveling and alignment and decompensation of affected dentition using 0.022" Roth preadjusted edgewise appliance. Midface distraction was carried out using RED device after the presurgical orthodontics using a custom made casted maxillary splint covering the entire maxillary dentition with hooks in the canine region. This was to hold maxilla as 1 unit during the distraction phase. Same surgical protocol was followed for all patients. High-level LeFort I surgery was done, and RED device (RED II System, Gebrüder Martin GmbH and Co. KG, Tuttlingen, Germany) was applied to all patients. As per the protocol, after a latency period of 5 days, distraction was initiated at a rate of 1 mm/day and continued as per the treatment plan. Once the distraction was completed, the consolidation period was for 8 weeks. External frames are then removed, and facemask traction was used for next 6 weeks from the hooks of appliance in the maxillary dentition. Postsurgical orthodontic treatment was then carried out for settling the occlusion. In retention phase, bonded lingual retainers were used in both arches along with a removable retention plate in the maxillary arch.
The amount of distraction done in each case is given in Graph 1. [Additional file 1] The cephalograms were traced using NemoCeph Dental Studio NX 2006, Version 6.0 (Nemotec ® , Madrid, Spain). X-Y coordinate system was used to differentiate between horizontal and vertical changes of midface and maxilla. The horizontal axis (X-axis) was a line through the nasion 6° upwards from Sella-Nasion line. The vertical line (Y-axis) was a line perpendicular to the horizontal axis through Nasion. Examined points were indicated as positive values when moved anterior and superior on X-Y coordinate and similarly negative value when moved posteriorly or inferiorly. Point A and ANS were used to record the position of the maxilla in horizontal and vertical plane to calculate the skeletal correction of the maxilla and also the relapse in the retention phase. Of 11 cases, 5 cases were selected randomly and retraced by the same operator after a gap of 1-week to check the intra-operator variability.
| Results|| |
The statistical analysis was performed using Statistical Package for Social Sciences (SPSS, Ver 11.5; Chicago, IL, USA) for Microsoft Windows. The analysis based on kappa statistics revealed that there was a statistically significant agreement between first and second evaluation (intra-operator agreement) for all linear as well as angular measurements performed in the study (P < 0.001) [Table 1]. Variables not normally distributed were transformed to normality using appropriate mathematical transformations. P values were obtained for repeated measurements by analysis of variance with Bonferroni's correction for multiple comparisons. P < 0.05 is considered to be statistically significant. Normality was tested using Shapiro-Wilk's test [Table 2].
|Table 1: The distribution of intra-operator variability for all Angular and Linear measurements |
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Comparison of angular measurements
The average postdistraction and 1-year postretention SNA, ANB, and nasolabial angle (NLA) were significantly higher compared with the corresponding average predistraction measurements (P < 0.001). The average postdistraction SNA, ANB, and NLA did not differ significantly compared with the corresponding average 1-year postdistraction measurements (P > 0.05).
The average predistraction SN-GoGn values did not differ significantly compared to the postdistraction and 1-year postdistraction SN-GoGn (P > 0.05). The average postdistraction SN-GoGn values did not differ significantly compared to the average 1-year postdistraction SN-GoGn values (P > 0.05) (Graph 2a) [Additional file 2] .
Comparison of linear measurements
The average postdistraction and 1-year postdistraction overjet, PtA-X axis, ANS-X axis and Mx 1-X axis were significantly higher compared to the corresponding average predistraction measurements (P < 0.001). The average postdistraction overjet, PtA-X axis, ANS-X axis and Mx 1-X axis did not differ significantly compared to the corresponding average 1-year postdistraction measurements (P > 0.05).
The average predistraction SNB, Na-Me, ANS-Me, PtA-Y axis, ANS-Y axis, and Mx 1-Y axis did not differ significantly compared to the corresponding postdistraction and 1-year postdistraction measurements (P > 0.05). The average postdistraction SNB, Na-Me, ANS-Me, PtA-Y axis, ANS-Y axis, and Mx 1-Y axis did not differ significantly compared to the corresponding average 1-year postdistraction measurements (P > 0.05) (Graph 2b).
| Discussion|| |
Distraction osteogenesis is a useful method for bone regeneration and has become a popular technique for the treatment of craniofacial skeletal dysplasia, commonly employed in patients with cleft lip and palate.  The maxillary hypoplasia in cleft lip and palate patients is because of genotype of the patient, cleft itself or because of surgical scaring. The choice for maxillary advancement between conventional Le Fort I surgery and DO depends upon the extent of the deformity. In a patient where the requirement of maxillary advancement is more than 8 mm, DO is preferred over conventional Le Fort I surgical procedure. 
The RED device, introduced by Polley and Figueroa for treatment of severe maxillary hypoplasia, is preferred over internal devices because of its advantages such as large distraction in 3 planes, good vector control, and predictable results with ease in application and removal of the device. ,,
The average change in position of skeletal and dental landmarks on X-axis (point A, ANS, and Mx 1) showed marked improvement and correction in skeletal disharmony. The present study reveals a significant correction in sagittal position of maxilla with DO, increase in SNA from 74° to 80.9°, the average increase in overjet noticed was 10.9 mm, that is, from −8 mm to +2.9 mm and the average improvement noticed in NLA was 19.4°. The average range of maxillary advancement was 9.91 mm in the present study. Meta-analysis by Cheung and Chua showed that most common range of maxillary advancement were in the range of 3-9 mm. 
The angular and linear measurements to assess the position of maxilla 1-year postdistraction showed statistically insignificant changes. The results of this study are in agreement with the findings by Saltaji et al.  and Sahoo et al.  The results of the present study are similar to that of Datana et al.  which highlights long-term cephalometric follow-up of the patients with UCLP and showed significant improvement in dentofacial structures with maxillary DO. The stable results with DO can be attributed to orthotropic autologous bone formation in pterygomaxillary area.  Kusnoto et al.  also noted changes in pterygoid region after distraction and stressed for prolonged retention. Singh et al.  concluded that maximum relapse occurred during first 6 months of postdistraction period and after that the outcomes were stable. Our study is in disagreement with the observation made by Wen-Ching Ko et al.  which showed significant horizontal relapse in 1-year follow-up.
| Conclusion|| |
Midface distraction with RED device provides a significant skeletal improvement in patients with cleft lip and palate. There was a marked improvement in dentofacial structures and results were stable during the retention phase 1-year postdistraction.
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[Table 1], [Table 2]