Alveolar clefts are complex anatomical defects in the upper jaw, significantly impacting a patient's dental and facial development. The surgical management of alveolar clefts is a highly debated topic within cleft care, with various protocols and techniques aiming to achieve optimal outcomes. This article provides a comprehensive overview of the diagnosis, treatment options, surgical techniques, and outcomes associated with alveolar cleft repair.

Understanding Alveolar Clefts and Their Impact

An alveolar cleft is more than just a gap in the maxillary arch; it's often visualized as a tornado-shaped defect, widening as it extends into the nasal cavity. This distortion affects surrounding anatomy, including the alar base of the nose, which lacks bony support on the cleft side.

Associated with alveolar clefts are distinct fistulas:

Nasolabial fistula: Located at the apex of the cleft in the labial sulcus, transitioning from loose wet labial mucosa to nasal mucosa.
Oronasal fistula: Extending from the incisive foramen to the alveolar process, a transition of attached palatal mucoperiosteum to nasal mucosa.

At the junction of these two fistulas, attached alveolar gingiva provides crucial support for erupting teeth. Dental development in patients with alveolar clefts can present with various anomalies, including missing, supernumerary, misshapen, or malpositioned teeth. Congenital absence of a permanent lateral incisor is common.

Core Treatment Goals for Alveolar Clefts

The overarching goals for successful surgical management of alveolar clefts are shared across different treatments. These aim to restore function and aesthetics:

Stable bone continuity of the maxillary arch.
Effective separation of oral and nasal cavities.
Appropriate maxillary arch form and transverse width.
A stable environment for the eruption of the canine on the cleft side.
Maintenance and bone support for all erupting teeth.
A keratinized gingival environment for erupted teeth.
Piriform bone support for the nasal base.
Preserved anterior vestibule.
Uninhibited facial growth.
Minimized donor site morbidity, if applicable.

Evolution of Alveolar Cleft Treatment

The journey of treating alveolar clefts has seen significant evolution. Early approaches, such as primary bone grafting in infancy, were popular in the mid-20th century but later fell out of favor due to concerns about iatrogenic impairment of facial growth.

Historical Approaches to Alveolar Cleft Surgery

Primary bone grafting: Advocated by Schmid and others, this approach in infancy was largely abandoned due to negative impacts on facial growth.
Secondary bone grafting: Introduced by Boyne in the 1960s, this method advocated treatment towards the end of the first decade of life. It aimed to minimize growth impairment while supporting adult dentition eruption and has since become the gold standard for comparison.
Gingivoperiosteoplasty (GPP): Skoog published his experience with "boneless bone grafting" in the same decade, marking the birth of GPP.

Today, all three options are still practiced, but secondary bone grafting remains the most widely accepted. New technologies, such as inductive proteins and distraction osteogenesis, continue to emerge, further diversifying the treatment landscape.

Key Surgical Management Techniques for Alveolar Clefts

Gingivoperiosteoplasty (GPP) Explained

GPP is a technique that aims to encourage bone formation using local mucoperiosteal flaps. It is often performed concurrently with primary lip repair. Not all infants are candidates, especially those with wide unilateral clefts or mesenchymal deficiency, as GPP could unnaturally constrict the arch form.

GPP Surgical Steps:

Nasal Floor Repair (Roof): The nasal floor, from the nasal sill to the incisive foramen, is closed by suturing the reconstructed lateral nasal wall to a superiorly based mucoperiosteal vomer flap (nasal flap). This separates the nasal from the oral cavity.
Oral Floor Repair (Floor): Inferiorly based mucoperiosteal flaps (oral flaps) are elevated from the oral edges of the alveolar cleft and sutured together to close the oral boundary.
Labial Border Closure: Anteriorly based triangular flaps (labial flaps) are brought from between the alveolar segments and flipped across the cleft to close the labial border.

This meticulous flap design creates a sealed, guided tissue regeneration chamber, directing bone growth across the cleft. Technical pitfalls include elevating flaps in the wrong plane, inaccurate flap planning, and trauma to the flaps. Careful dissection is needed if a deciduous tooth follicle is encountered.

Primary Bone Grafting Overview

Primary bone grafting protocols typically involve a staged approach. This includes molding the maxillary arch segments during the first year of life, followed by stabilization of the arch with an autogenous bone graft in infancy (around 4-6 months).

Rosenstein and Dado's approach uses a maxillary appliance before lip repair to align segments. After lip repair, the appliance is modified to allow lip musculature to mold and close the anterior cleft. The appliance continues for 6-8 weeks post-surgery, and the palate is closed by one year of age.

Secondary Bone Grafting: The Gold Standard

Secondary bone grafting is currently considered the gold standard for surgical management of alveolar clefts. It is typically performed during the mixed dentition phase, between ages 6 and 11, when the permanent canine root is one-fourth to one-half formed.

Pre-surgical Considerations:

Orthodontist and surgeon discuss timing, fate of adjacent teeth, and arch expansion.
Dental issues like poor hygiene or caries must be addressed.
Primary teeth adjacent to the cleft may be extracted 3-6 weeks prior to ensure a viable mucosal seal.
Arch expansion can be done before or after grafting. Preoperative expansion utilizes segment mobility to achieve optimal arch width, while postoperative expansion waits 6-8 weeks after surgery.

Secondary Bone Grafting Technique (Modified Abyholm):

Pre-operative preparation: Chlorhexidine mouthwash and nasal antibiotic ointment are used.
Patient Positioning: Supine with support under the posterior iliac crest for graft harvest, maintaining two sterile fields.
Flap Elevation: A superiorly based mucoperiosteal flap is raised off the lesser segment, including sufficient attached gingiva.
Fistula Closure: Opposing alveolar cleft mucosal surfaces are separated into upper (nasal lining) and lower (oral lining) flaps. The nasal lining flaps are sutured together, and then the oral lining flaps are closed to repair the oronasal fistula. If the cleft is wide, anterior hard-palate tissue may be raised as posteriorly based flaps.
Bone Harvest: Iliac crest cancellous bone graft is the gold standard donor source. It's harvested using a curette or gouge. A cortical strut may also be harvested to reconstruct the pyriform rim.
Graft Placement: The harvested bone is packed into the prepared graft site, compressing the pieces. Any remaining bone can augment the deficient maxillary bone in the cleft-side piriform rim.
Flap Closure: The lesser-segment mucoperiosteal buccal sulcus flap is advanced over the labial surface of the graft and secured. Dehiscence is most common at the junction of this flap and the oral lining repair.

Postoperative Care: Gentle oral hygiene, antibiotic mouthwash, soft diet for 6 weeks. Graft preservation is assessed radiographically at 8-10 weeks.

Alveolar Distraction Osteogenesis (TDO)

For "ungraftable" or "recalcitrant" alveolar clefts with unhealthy scarred gingiva, large fistulas, or previous graft failures, TDO offers a valuable solution. TDO moves a tooth-bearing segment into the gap, closing the fistula and converting a wide cleft into a narrow one amenable to traditional grafting.

Types of Alveolar TDO:

Horizontal TDO of a tooth-bearing alveolar segment: Creates a transport segment (2-3 teeth) from the distal alveolus, separating it from the maxilla. A distraction device is applied, gradually closing the alveolar cleft until it touches the premaxilla. This is typically reserved for patients past mixed dentition due to risk to unerupted follicles.
Vertical alveolar TDO: Useful for augmenting previously grafted clefts with severe vertical deficiency and scarred mucogingiva. A transport segment of superior maxillary bone is slowly lowered, leveling the alveolar ridge. A minimum of 10mm vertical bone height below the maxillary sinus is needed, or an onlay cortical graft may be performed first.

TDO Protocol: Activation begins 5 days post-operation at 0.5-1 mm/day. The device remains for 8-12 weeks consolidation, followed by removal and secondary grafting of the residual cleft.

Bone Morphogenic Protein (rhBMP-2) in Cleft Repair

Recombinant human bone morphogenic protein-2 (rhBMP-2) is a mitogen that stimulates osteoblastic activity and induces bone formation. Approved for human spine fusion, it is being explored for alveolar augmentation and cleft treatment.

Some trials suggest rhBMP-2 with a collagen sponge can improve bone healing, reduce donor morbidity, and lower costs compared to autogenous iliac crest grafts, especially in skeletally mature patients. However, its risk-benefit profile in growing patients is still largely unknown. Potential complications include ectopic bone formation, resorption, hematoma, swelling, painful seroma, and theoretical concerns like carcinogenicity.

Late Bone Grafting Considerations

Delaying alveolar bone grafting until skeletal maturity, particularly for patients needing a LeFort I osteotomy, has largely been abandoned. This is because canine eruption into a bone graft provides better long-term support.

For adults presenting with untreated alveolar clefts in permanent dentition, a combined segmental orthognathic and bone grafting procedure is required. However, outcomes are generally less favorable than grafting in mixed dentition. The goal shifts from supporting erupted teeth to providing bone stock for prosthetic placement.

Outcomes and Prognosis of Alveolar Cleft Treatment

Outcomes for surgical management of alveolar clefts vary widely depending on the technique and specific patient factors. Follow-up evaluations and outcome measures also vary across studies, making direct comparisons challenging.

GPP Outcomes and Challenges

Initial evaluations of the Millard GPP protocol, often with Latham device pre-molding, reported bony bridge formation in 63% of unilateral and 83% of bilateral clefts, with a low percentage requiring secondary bone grafting. However, other studies reported concerns such as vertical maxillary growth disturbance and high rates of anterior crossbite.

More recent evaluations of nasoalveolar molding (NAM) combined with GPP reported bone formation in 80% of clefts, with 73% not requiring secondary bone grafting. These studies also found no adverse effect on midface growth up to 18 years of age, though independent reproduction of these results is still needed.

Primary Bone Grafting Results

Rosenstein et al. reported no cephalometric evidence of impaired growth in their primary grafting cohort compared to similar ungrafted groups. Hathaway et al. also found no difference in arch form. However, Ross's evaluation of multiple centers suggested primary grafting might negatively affect midface growth, though it wasn't clear if this was worse than secondary grafting between ages 4 and 10.

Secondary Bone Grafting Success Rates

Success rates for secondary alveolar bone grafting range from 70-80% in most studies, and over 90% in some. This success is often linked to factors like the timing of graft placement relative to canine eruption. Grafting adjacent to fully erupted teeth is associated with higher failure rates.

Factors contributing to improved graft success include:

Stable healed graft prior to canine eruption.
Canine root formation of one-fourth to one-half formed at graft placement.
Standardized protocols and experienced surgeons.

Distraction Osteogenesis Success

Alveolar distraction osteogenesis is reserved for complex cases where other methods have failed. Its success lies in its ability to address wide,

Surgical Management of Alveolar Clefts