Rotating a Segmental Maxilla to Close a Serious Vertically Displaced Alveolar Cleft

Supplemental Digital Content is available in the text.

Summary:

In recent years, alveolar bone grafting has emerged as the first treatment choice for space closure in the secondary dentition. Despite this, a high possibility of failure still exists for patients with a vertical discrepancy of cleft segments. This is attributed to the absence of valid contact between the grafted bone and the surfaces of bone segments in the cleft region. In cases of minor discrepancies, the vertical distance can be reduced orthodontically, allowing for subsequent alveolar bone grafting.¹ However, in severe cases, isolated orthodontic treatment is not viable due to a high risk of periodontal problems and increased tooth mobility. Under the circumstances, surgical intervention is essential. Herein, we report a case in which the alveolar segment is aligned using a novel application of segmental maxillary osteotomy to rotate the segment with a subperiosteal tunnel. Rigid fixation of the segment in the desired position is then performed with concurrent bone grafting. Therefore, performing segmental maxillary osteotomy before bone grafting could be an alternative to correcting the vertical discrepancy encountered in cleft patients.

CASE STUDY

Clinical examination of a 12-year-old girl revealed the upper left lateral incisor was congenitally absent, while the upper left central incisor and canine had erupted completely, both of which inclined toward the cleft region. The patient had undergone operations for a unilateral cleft lip and palate 2 years ago. In addition, a conventional bone graft had been attempted, but failed. Therefore, we determined that surgical intervention to reposition the bone segments may be a more suitable treatment option for this patient.

SURGICAL COURSE

The surgery was performed under general anesthesia. Incisions along the cleft margins and a vertical incision in the buccal mucosa were made [see figure, Supplemental Digital Content 1, which displays a schematic diagram of the incision design. A, Diagram of the labial and palatal incision design. B, Diagram of the incision design (bottom view). C, Coronal diagram of palatal incision showing the position relative to the palatal vessels, http://links.lww.com/PRSGO/B390)]. Subperiosteal dissection was performed to expose the site of the horizontal osteotomy with a tunnel.^2,3 Virtual presurgical planning was done to determine a safe osteotomy line and direction, minimizing the risks of the procedure and enhancing accuracy and efficiency [see figure, Supplemental Digital Content 2, which displays virtual surgical planning. A and B, Anteroposterior and lateral virtual surgical planning images, showing the sites of the horizontal osteotomy and the interdental osteotomy. C and D, Virtual surgical planning images demonstrating the proposed position of the dentoalveolar segment, http://links.lww.com/PRSGO/B391)].

The osteotomy was made ≥5 mm above the root of the tooth with a piezoelectric osteotomy. Additionally, a small incision parallel to palatal vessels was made to expose the cortical bone on the palatal side. The buccal and palatal cortical plate was cut through with a thin osteotome to ensure complete mobilization of the osteotomized dentoalveolar segment. After the segment was rotated to the desired position, it was fixed using plates. Cancellous bone harvested from the iliac crest was grafted into the modified cleft space. Tension-free closure of the cleft site was then performed (Fig. 1). Finally, the segment was wired into a splint, which was kept in place for 4 weeks. (See Video 1 [online], which is intended to provide a general understanding of the surgical procedure in a cleft patient with a severe vertical discrepancy.)

Fig. 1.

Steps of the operation. A, Incision of the alveolar cleft and segmental maxillary osteotomy. B, Intraoperative photograph of the site of the horizontal osteotomy and interdental osteotomy, and the rigid fixation of dentoalveolar segment. C, Placement of the bone graft. D, Closure of the flaps.

Video 1. Vertical discrepancy procedure. Video 1 from “Rotating a segmental maxilla to close a serious vertically displaced alveolar cleft”.

Download video file ^{(76.6MB, mp4)}

DISCUSSION

The difficulty of this case arose from a lack of sufficient contact between the grafted bone and the alveolar segments. Traditional alveolar bone grafting with orthodontic treatment was not suitable in this case. To achieve alignment or rotation of the malpositioned lesser segment, there would be a high risk of tooth movement, as well as overeruption of the canine.⁴ This can result in bone loss and periodontal defects, compromising the bony support of the dentition. Studies have demonstrated that the success of grafting correlated directly with the preoperative presence of adequate bone on the mesial surface of the canine.⁵ Thus, in this case, the defect cannot be repaired solely with a bone graft; one solution to this problem is to correct vertical discrepancy by surgical repositioning of the laterally displaced maxilla.^6–9

Rotation of the osteotomized dentoalveolar segment was considered risky because a large amount of segmental rotation could compromise blood supply and the survival of the segment. Instead of choosing a vestibular incision which provided wide access and adequate bone exposure,¹⁰ we constructed a horizontal subperiosteal tunnel to minimize potential damage to the blood supply. In addition, to avoid stripping the palatal mucosa, a small incision parallel to the palatal vessels was designed. Given that stabilizing such a small size dentoalveolar segment is difficult, virtual preoperative planning was done to confirm the position of plates to be placed so as to diminish the risk of damage to the dental roots and to achieve maximum stability. The dentoalveolar segment was fixed securely to bilateral alveolar segments to withstand the traction forces of the soft tissues and ensure further stability. Furthermore, a matter of the extent of rotation of the alveolar segment is troublesome. On the one hand, we need to reposition the dentoalveolar segment to a manageable position to correct the vertical discrepancy. On the other hand, the posterior gap produced by rotation of the segment could not be too wide. Ideally, a favorable location of segment was replaced without influencing the reconstruction of posterior gap with cancellous bone. Clinical examination at 6-month follow-up showed that the patient had excellent soft-tissue coverage at the cleft area, normal color of the buccal and palatal mucosa, and a stable alveolar arch. Furthermore, a computed tomography scan image revealed formation of a new bone and restoration of the continuity of the dental arch. “Bridging” of the cleft defect had been achieved [see figure, Supplemental Digital Content 3, which displays postoperative computed tomography scan images. A and B, Anteroposterior and lateral view with a 3-dimensional reconstruction showing stabilization of the dentoalveolar segment at 6 months post operation. C and D, Axial and coronal view showing formation of a new bone (marked with a red arrow), http://links.lww.com/PRSGO/B392].

This is a particularly valuable technique to correct the vertical discrepancy encountered in cleft patients. As we reposition the dentoalveolar segment to a favorable and predictable position, valid contact of the grafted bone with bony segments increases, promoting bony bridging. Consequently, the failure risk associated with bone grafting is reduced. Different from Lefort I osteotomy, it is merely a segmented alveolar bone to help facilitate bone grafting, unification of the arch, and reduce morbidity. In addition, the rotation also reduces tension on the buccal flaps, facilitating ease of closure.

CONCLUSIONS

Segmental maxillary osteotomy with concurrent bone grafting offers an alternative approach in the closure of clefts with severe vertical discrepancy. Rotation and fixation of an osteotomized alveolar bone in the desired position were performed to make the gap smaller and more manageable, which facilitates successful bone union and fill, minimizes prolonged orthodontic treatment, and eliminates the need of second bone graft. With further refinement, even better outcomes may be achieved in the future.

ACKNOWLEDGMENT

The research protocol was censored and approved by the Ethic Committee of West China Hospital of Stomatology, Sichuan University (Approval No. WCHSIRB-D-2017-143).