|Year : 2018 | Volume
| Issue : 2 | Page : 88-96
Cephalometric evaluation of patients treated by maxillary anterior segmental distraction
Shanahaz Kuzhippayi Saidalavi, Balakrishna Shetty, Goutham Reddy, Sunil Muddaiah, Sanju Somaiah, Roopa Sidde Gowda
Department of Orthodontics and Dentofacial Orthopedics, Coorg Institute of Dental Sciences, Kodagu, Karnataka, India
|Date of Web Publication||26-Jul-2018|
Dr. Shanahaz Kuzhippayi Saidalavi
Department of Orthodontics and Dentofacial Orthopedics, Coorg Institute of Dental Sciences, Virajpet, Kodagu, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Maxillary hypoplasia secondary to repaired cleft lips and palates is common. The extent of hypoplasia is dependent on several factors. It is not possible to correct maxillary hypoplasia by conventional orthodontics and relapse is common after orthognathic advancement of the maxilla with or without grafts. Distraction osteogenesis (DO) offers a promising alternative for the management of congenital and acquired facial deformities that require bone lengthening. It is less invasive than traditional surgical techniques, requires less surgical time, and eliminates the need for a donor site operation. In addition, simultaneous soft-tissue expansion may improve long-term skeletal stability. DO allows the body's natural healing mechanisms to generate new bone for augmenting or lengthening bone. The purpose of this study was to enumerate and compare dental, skeletal, and soft-tissue changes, and postoperative stability using cephalometric analysis following anterior maxillary DO in cleft patients. Aims and Objectives: (i) The aims and objectives of this study were to enumerate and compare dental, skeletal, and soft-tissue changes, and postoperative stability using cephalometric analysis following premaxillary DO and (ii) to draw clinical inference from the above results. Methods: Seven female patients underwent anterior maxillary DO with a mean age of 19 years, and the anterior movement of premaxillary segment was generated by tooth-borne distractor with a rapid maxillary expansion screw. The distraction of the premaxilla was stopped after achieving a positive profile and sufficient space to align the maxillary dentition. After the consolidation period, the distractor was removed and orthodontic treatment was started with fixed appliances to level the teeth. Cephalometric data of patients were collected before treatment (T1), after distraction (T2), and 6 months after distraction. Comparison between time periods T1–T2, T1–T3, and T2–T3 were done to evaluate the dental, skeletal, and soft-tissue changes brought by DO. Results: In all the patients, the treatment objective was achieved with a positive overjet and improved profile without changing the position and intermaxillary relation of the posterior. There was a significant horizontal increase of the premaxilla with a definite gain in the maxillary dental arch length for alignment of the maxillary dentition with a downward and backward movement of the mandible. Conclusion: Maxillary DO offers an effective technique to transpose the maxilla forward and downward in moderate-to-severe maxillary retrusion. DO offers better stability due to the gradual expansion and lengthening of the soft tissue in response to the gradual traction. It avoids the complication of acute reconstructive surgical methods and minimal trauma when compared to other alternative surgical methods. It also shortens the overall treatment time due to reduced need for comprehensive treatment time.
Keywords: Anterior maxillary distraction osteogenesis, distraction osteogenesis, premaxilla
|How to cite this article:|
Saidalavi SK, Shetty B, Reddy G, Muddaiah S, Somaiah S, Gowda RS. Cephalometric evaluation of patients treated by maxillary anterior segmental distraction. J Cleft Lip Palate Craniofac Anomal 2018;5:88-96
|How to cite this URL:|
Saidalavi SK, Shetty B, Reddy G, Muddaiah S, Somaiah S, Gowda RS. Cephalometric evaluation of patients treated by maxillary anterior segmental distraction. J Cleft Lip Palate Craniofac Anomal [serial online] 2018 [cited 2019 Jun 18];5:88-96. Available from: http://www.jclpca.org/text.asp?2018/5/2/88/237638
| Introduction|| |
Maxillary hypoplasia is a common developmental problem in cleft lip and palate (CLP) deformities. Maxillary hypoplasia results from a combination of a congenital reduction in midfacial growth and the effects of the surgical scar from cleft palate repair.
Maxillary hypoplasia secondary to repaired cleft lips and palates is common. Several factors such as the degree of the cleft deformity and the extent of scar tissue formed after surgical repair affects the amount of hypoplasia seen. The maxillary hypoplasia cannot be corrected by conventional orthodontics, and relapse is common after the orthognathic procedure for maxillary advancement.
Distraction osteogenesis (DO) is the gradual mechanical traction of bone segments at an osteotomy site to generate new bone. This was used first by Codivilla in 1905, but became popular through the work of llizarov.
DO has come into use for reconstructing craniofacial structures after Snyder et al. (1973) reported bone lengthening of a canine mandible. In 1992, McCarthy et al. (1992) reported on their experience with mandibular lengthening by gradual distraction in patients with hemifacial microsomia and Nager syndrome More Details. Since then there has been an explosion of reports in the literature on DO in the craniofacial skeleton. Although application to the mandible is more frequent, advancement of maxillary structures has also been reported.
DO advanced in the field of maxillofacial surgery due to its versatility, simplicity, and possibility of avoiding bone grafts, infections, blood transfusions, or intermaxillary fixation for long periods of time. In addition, DO establishes the augmentation of the soft tissue simultaneously with the bone.
DO offers promising alternative for the management of congenital and acquired facial deformities that require bone lengthening. It eliminates the need for a donor site operation and allows simultaneous soft-tissue expansion which may improve long-term skeletal stability. DO allows the body's natural healing mechanisms to generate new bone for augmenting or lengthening bone.
DO in the treatment of severe maxillary hypoplasia in cleft and palate patients is as follows:
- Reproducible and valuable alternative to standard orthognathic surgical procedures
- Allows for global improvement in facial esthetic
- Allows for a maxillary correction in patients during the period of mixed dentition
- Allows either for an unchanged or better velopharyngeal function.
The statistical analysis was performed using SPSS version 23, IBM, Armonk, NY, USA. Descriptive statistics were calculated which included the mean, standard deviation, and median of the data collected. The comparison of the data (T1–T2, T2–T3, and T1–T3) was analyzed using a nonparametric test, i.e., Wilcoxon signed-rank test, and the differences associated with a value of P < 0.05 were considered as statistically significant.
Case selection protocol
The patients were selected from patients reporting to the Department of Orthodontics and Dentofacial Orthopedics with maxillary hypoplasia secondary to unilateral cleft palate Exclusion criteria includes previous history of orthodontic treatment and/or orthognathic surgery and presence of a noncontinuous soft-tissue contour at the level of the chin indicating a chin strain.
Here, in this study, we used the Cupar technique. It is, in essence, a minor version of the total maxillary osteotomy down-fracture technique [Figure 1].
A buccal vestibular incision is created, allowing direct access to the anterior lateral maxillary wall, pyriform aperture, and nasal floor and septum. The sequence of osteotomies is operator dependent, but the general procedure involves the elevation of nasal mucosa from the superior surface of the maxilla. The nasal septum is released from the maxillary crest. The horizontal osteotomy is completed, and the vertical osteotomy is then performed bilaterally between the teeth. Through this vertical cut, the transpalatal osteotomy is completed with piezo device; a finger is placed on the palatal mucosa to palpate the osteotome. After the osteotomy is done, the anterior maxilla is mobilized with spatula spreader or Smithson's spreader in all direction. After achieving complete mobility of maxilla, the hyrax appliance [Figure 2] is adapted and cemented with proper isolation.
Custom-made tooth-borne distractor [Figure 3] was constructed on study model using hyrax screw with molar, and premolar bands were soldered to orthodontic hyrax screw for construction of the distraction device. The screw was aligned in the sagittal plane to achieve an anteroposterior vector parallel to the occlusal plane and facial midline.
Activation of the distraction appliances started on the fifth postoperative day at a rate of 1 mm/day. The duration of the activation period was determined clinically by the severity of the maxillary hypoplasia and anterior reverse dental crossbite. This was followed by a consolidation period of 12–16 weeks. All the patients tolerated the distraction procedure well. There was no surgical morbidity in any of the patients. After 3–4 months of consolidation, the appliance was removed.
Digital lateral cephalogram was taken at rest with no lip strain, well-defined, and identifiable chin structures on the radiograph. A sample consisting of minimum of seven patients cephalometric radiographs was taken predistraction: T1 [Figure 4] and postdistraction: T2 [Figure 5] and 6 months after T2: T3 [Figure 6].
Landmarks used which are as follows [Figure 7], [Figure 8], [Figure 9]:
|Figure 7: Cephalometric angular measurements of skeletal and soft-tissue structures. (1) SNA: angle between Sella-Nasion-A point, (2) SNB: angle between Sella-Nasion-B point, (3) ANB: angle between A Point-Nasion-B point, (4) Y-Axis: andle between Frankfurt Horizontal and Sella-Gnathion, (5) SN/PP: angle between Sella-Nasion and palatal plane, (6) subnasale, (7) sublabiale|
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|Figure 8: Cephalometric linear measurements of skeletal and soft-tissue structures. (1) NV-A: perpendicular distance from A point to Nasion vertical line (Nasion verticle line: perpendicular line from Nasion to Frankfurt horizontal), (2) NV-Pog: perpendicular distance from Pogorion to Nasion verticle line, (3) Co-A: lione between condylion to A point, (4) N-ANS: upper anterior facial height (line between Nasion-Anterior Nasal Spine), (5) ANS-Me: lower anterior facial height (line between Nasion-Anterior Nasal Spine), (6) E-St: distance from tip of the upper lip to E-line, (7) E-Sm: distance form tip of the upper lip to E-line, (8) NV-Nose tips: perpendicular distance from tip of the nose to Nasion vermicular line|
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|Figure 9: Dental cephalometric measurements. (1) U1/SN: angle between axis of upper central incisor and Sella-Nasion, (2) U1/NA: angle between axis of central incisor and Nasion-A point, (3) U1/NA: perpendicular distance from incisal edge of upper central incisor and Nasion-A point, (4) Overjet: distance between incisal edge of upper and lower central incisors|
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- SNA, NV-A, ANB, Co-A, and the length of palatal plane (anterior nasal spine-posterior nasal spine [ANS-PNS]) were evaluated to determine the amount of distraction
- SNB, NV-Pog, and Y-axis were evaluated to reveal the effects on the mandible. N-Me, (Nasion-Menton) N-ANS, and ANS-Me were measured to determine the alterations in facial heights
- SN/PP angulation of the palatal plane was measured. U1/SN, U1-NA, U1/NA, and overjet were measured to show the changes of upper central incisor
- E-St, E-Sm, subnasale, sublabial, and NV-Nose tip were evaluated to determine the soft-tissue alterations.
The statistical analysis was performed using SPSS 23 software. Descriptive statistics were calculated which included the mean, standard deviation, and median of the data collected. The comparison of the data (T1–T2, T2–T3, and T1–T3) was analyzed using a nonparametric test, i.e., Wilcoxon signed-rank test, and the differences associated with a value of P < 0.05 were considered as statistically significant.
| Results|| |
The present study was conducted to enumerate and compare dental, skeletal, and soft-tissue changes, and postoperative stability using cephalometric analysis following premaxillary DO in cleft patients. The cephalometric data collected before treatment (T1), after distraction (T2), and 6 months later distraction (T3) was fed in the SPSS software (IBM version 23). Descriptive statistics were calculated which included the mean, standard deviation, and median of the data collected [Table 1]. The comparison of the data was analyzed using a nonparametric test, i.e., Wilcoxon signed-rank test, and the differences associated with a value of P < 0.05 were considered as statistically significant [Table 2].
|Table 1: Mean (M) and standard deviation (SD) of measurements taken lateral cephalogram radiographs at T1(before treatment), T2 (after distraction) and T3 (6 months after distraction)|
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|Table 2: Comparison of measurements taken before T1 (treatment), T2 (after distraction) and T3 (6 months after distraction)|
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Comparison between T1–T2 (before treatment-after distraction)
During DO, the maxilla was horizontally advanced as indicated by the significant change in the SNA angle from a mean of 74.07° to 77.14°. An increase in NV-A and Co-A from −9.14 mm to −7.14 mm and 75.00 mm to 77.42 mm, respectively, revealing a definite forward movement of the premaxilla. The maxillary dental arch length was significantly increased from 46 mm to 48.28 mm. A significant change was seen in Y-axis from a 61.00° to 62.21° showing a downward and backward movement of the mandible. The overjet showed a significant change from −4.4 mm to 1.2 mm indicating achievement of positive overjet. The soft-tissue change was noticed in E-St from a value of −9.28 mm to −7.00 mm showing an improvement in profile.
Comparison between T1–T3 (before treatment – 6 months after distraction)
A statistically significant alteration in ANS-PNS from 46 mm to 47 mm indicated an increase in the length of the maxillary dental arch. A change in the Co-A and NV-A from 75 mm to 76 mm and −9.14 mm to −7.14 mm, respectively. A downward movement of the mandible was indicated by the increase of ANS-Me from 60.64 mm to 63.57 mm and a backward movement of the mandible by the change in the value of Y-axis from 61° to 62.42°. A significant increase in overjet is seen from −4.42 mm to −0.21 mm. An increase in the value of E-St from −9.28 mm to −7.92 mm indicated an improvement in profile.
Comparison between T2–T3 (after distraction – 6 month after distraction)
Statistically there was an alteration in the values of Co-A from 77.42 mm to 76.07 mm showing a backward movement of the maxilla and ANS-PNS from 48.28 mm to 47 mm indicating a slight decrease in the length in the dental arch denoting a decrease in the elongation of the premaxilla.
| Discussion|| |
Anterior maxillary DO provided an easier method of improving the profile of the patients by moving the premaxilla in anterior and downward movement, thereby gaining space in the upper arch for the alignment of the maxillary dentition [Figure 10], [Figure 11], [Figure 12].
When pretreatment period (T1) and the distraction period (T2) of the study were compared, there was a definite horizontal movement of the premaxilla which was brought by the intraoral distraction appliance. The mandible showed a clockwise rotation which was caused by the forward and downward movement of the maxilla resulting in the increase in the lower facial height. The maxillary arch showed a marked increase in length with an increase in the overjet and an improved patient profile.
The success of DO depends on the response to mechanical stretching of the initial callus formed at the osteotomy site. Therefore, a waiting period of 7 days after surgery to allow time for initial callus formation and repair of the periosteal tissues to occur. The osteotomy site in the lengthened maxilla showed a complete regeneration of the alveolar crest which was only apical to the cementoenamel junction. The buccal plate was intact, and there was a complete regeneration of the trans-septal fibers. Therefore, the space created in the alveolar bone could be readily used to correct severe crowding.
When pretreatment period (T1) and 6 months postdistraction (T3) were compared the results gained due to the distraction process was still seen, i.e., the arch length gained, overjet gained, etc., showing that DO helped in correction of the maxillary hypoplasia.
However, when the period of distraction (T2) with the 6 months postdistraction (T3) was compared there has been a minute relapse in the amount of length gained in the maxilla due to distraction even though there was not much change in the patient profile. The main reason for relapse is the contraction of the scar tissue of the palate after maxillary advancement, and the other reason is the pressure of the soft tissue on the maxillary advancement gained by anterior maxillary DO. The relapse caused by the contraction of the scar tissue of the palate and soft-tissue pressure can be minimized by increasing the consolidation period of the 12 weeks, thereby allowing more bone formation and more adaptation of the soft tissue of the face on the advanced maxilla.
Various studies showed that anterior maxillary segmental distraction can effectively correct the hypoplastic maxilla and severe dental crowding associated with CLP by increasing the midface convexity and dental arch length while preserving velopharyngeal function and dental crowding can be corrected without requiring tooth extraction all of which are in agreement the present study.,,,,,
DO presented better stability than conventional orthognathic procedure and the upper incisor angulation stayed increased in conventional method but in DO it remained constant.,
Greater precision can be achieved using a tooth-borne rather than a bone-borne distractor, as the orthodontic brackets are fixed to the precise tooth morphology rather than an inclined palatal vault. The method of fixing the appliance to the teeth with bands also allows better tooth position control than an acrylic splint, and it may also be more difficult to remove an acrylic splint than a band. However, problems with anchorage and the proclination of the anterior teeth may still occur if a tooth-borne distractor is used.,,
Studies conducted in growing children with CLP patients showed great improvement in dentofacial structure after maxillary DO and stability in maxillary skeletal advancement and the achieved dentoskeletal treatment outcome was partly diminished.,,,,,,
External and internal distraction devices have been used for maxillary DO. Internal maxillary distraction has definite advantages over the RED system in the form of good patient compliance and convenience. The main advantages are less physical and psychological stress on the patients and a shorter duration of hospitalization. Disadvantages of internal distraction when compared to external distractors include techniques sensitive fixation methods, less flexibility in vector management, and vector control and limited quantum of achievable advancement.
| Conclusion|| |
The results of this study showed that the maxilla of cleft patients can be lengthened using anterior maxillary DO using an intraoral distraction device with long-term stability, increase in the arch length, and improvement of the profile of the patient from concave to convex.
Maxillary advancement in CLP patients using DO appears to be a fairly stable procedure. The DO technique can effectively transpose the maxilla forward and downward in moderate-to-severe maxillary retrusion. For the correction of severe midfacial hypoplasia, DO seems to be the most favorable when substantial corrections are needed. This is mainly because DO is accompanied by lengthening of the related soft tissues of the face and the oral cavity.
The two main advantages of distraction osteogenesis to correct maxillary hypoplasia secondary to cleft deformity which are as follows:
- There is usually no need for a bone graft
- There is a simultaneous expansion of the soft tissue.
The disadvantage of the anterior maxillary DO using intraoral device is that it cannot perform a three-dimensional correction.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]
[Table 1], [Table 2]