Optimal Timing for Nasal Cartilage Molding in Presurgical Nasoalveolar Molding

Sir:

The essential objectives of presurgical nasoalveolar molding in unilateral clefts are to align and approximate the maxillary hemialveolar segments, simultaneously support and mold the deformed nasal cartilages, correct nasal tip projection and centering, and lengthen the deficient cleft side columella, prior to the primary lip repair. These are achieved by using acrylic plates with nasal stents to mold the malleable alveolar processes and immature nasal alar cartilages. After Grayson et al.'s detailed description,¹ many different nasoalveolar molding techniques have been reported. All intraoral methods utilize an alveolar molding appliance, which is custom-fabricated to conform to the shape and size of the maxillary hemialveolar processes registered from the pretreatment maxillary impression. Nasal molding is undertaken through controlled activation and addition of soft reline material to a cartilage-molding nasal bulb on a nasal stent that is embedded into the appliance and emerges from its labial vestibular flange.

The reported literature exhibits wide variation in the timing at which nasal molding is commenced, with some authors describing starting very early while others recommend waiting until most of the lateromedial correction of the greater segment position has been accomplished² or when the alveolar cleft has been reduced to below 6 mm.¹ Theoretically, it would be advantageous to undertake nasal cartilage molding as early as possible, to achieve more long-lasting molding of the relatively plastic immature cartilage and avoid the elastic rebound that would result from older, more mature and less plastic cartilage.³ However, at the pretreatment stage, the greater hemialveolar maxillary segment, pyriform margin, and alar base of the noncleft side are displaced superolaterally by the discontinuous and asymmetric muscle pull extraorally and the tongue pressure intraorally, while the alar base on the cleft side is deficient and displaced posterolaterally (Fig. 1, above).^4,5 Pressure from the stent if added at this stage, when the segments are wide apart and deviated, imposes sagittal stretching on the already severely laterally stretched cleft-side lower alar cartilage, and can potentially lead to notching in the region of the medial angle of the ala, mucosal lining trauma, and tissue breakdown. With the return of the displaced greater segment back toward the midline during the course of orthopedic treatment (Fig. 1, below), the right and left skeletal nasomaxillary and pyriform bases are in an improved three-dimensional relationship, and the nasal cartilages and soft tissues are in an anatomically more correct and compliant position to favorably undergo molding. Nasal molding also introduces a reciprocal sagittal force vector that additionally molds the anterior alveolus (Fig. 2). In my view and experience, nasal molding should be begun when most of the lateromedial positional correction of the greater segment has been achieved, as evidenced by (1) the return of the incisive papilla toward and close to the midsagittal plane of the face; (2) greater than two-thirds reduction in cleft width for wide clefts (for not very wide clefts, the incisive papilla guideline takes precedence), and (3) visible reduction of the nasomaxillary asymmetry. Orthopedic alignment should be paced to reach this stage expeditiously.

Fig. 1.: (Above) Pretreatment presentation exhibiting the characteristic unilateral cleft defect and deformity. (Below) Improvement in anatomical relationships with progress of orthopedic treatment. Note the return of greater segment and incisive papilla toward the midline.

Fig. 2.: Blanching on anterior alveolus indicating additional molding effect generated from reciprocal force vector of nasal molding.

Sunjay Suri, M.Orth.R.C.S.(Edin.), F.R.C.D.C.

Department of Orthodontics

University of Toronto, Faculty of Dentistry

124 Edward Street, Room 519-B

Toronto, Ontario, Canada M5G 1G6 and

Department of Dentistry

The Hospital for Sick Children

555 University Avenue

Toronto, Ontario, Canada M5G 1X8

DISCLOSURE

The author has no commercial associations or financial disclosures to make that might pose or create a conflict of interest with information presented in this article.