PEDIATRIC/CRANIOFACIAL Maxillary Hypoplasia in the Cleft Patient: Contribution of Orthodontic Dental Space Closure to Orthognathic Surgery Justine C. Lee, M.D., Ph.D. Ginger C. Slack, B.S. Ryann Walker, B.A. Lindsay Graves, B.A. Sandra Yen, B.A. Jessica Woo, B.A. Rishal Ambaram, B.A. Martin G. Martz, D.D.S., M.S. Henry K. Kawamoto, Jr., M.D., D.D.S. James P. Bradley, M.D. Los Angeles, Calif.
Background: Cleft lip and palate surgery in the developing child is known to be associated with maxillary hypoplasia. However, the effects of nonsurgical manipulations on maxillary growth have not been well investigated. The authors present the contribution of orthodontic dental space closure with canine substitution to maxillary hypoplasia and the need for orthognathic surgery. Methods: Cleft lip/palate and cleft palate patients older than 15 years of age were reviewed for dental anomalies, orthodontic canine substitution, and Le Fort I advancement. Skeletal relationships of the maxilla to the skull base (SNA), mandible (ANB), and facial height were determined on lateral cephalograms. Logistic regression analyses were performed to estimate odds ratios. Results: Ninety-five patients were reviewed (mean age, 18.1 years). In 65 patients with congenitally missing teeth, 55 percent with patent dental spaces required Le Fort I advancement. In contrast, 89 percent who underwent canine substitution required Le Fort I advancement (p = 0.004). Canine substitution is associated with a statistically significant increase in maxillary retrognathia when compared with dental space preservation on lateral cephalograms (mean SNA, 75.2 and 79.0, respectively; p = 0.006). Adjusting for missing dentition, logistic regression analyses demonstrated that canine substitution is an independent predictor for orthognathic surgery (OR, 6.47) and maxillary retrusion defined by SNA < 78 (OR, 8.100). Conclusions: The coordination of orthodontia and surgery is essential to cleft care. The authors report a strong association between orthodontic cleft closure using canine substitution with maxillary hypoplasia and subsequent Le Fort I advancement, and suggest systematic criteria for management of cleft-related dental agenesis. (Plast. Reconstr. Surg. 133: 355, 2014.) CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.
urgical maneuvers for cleft correction in the developing child are known to be associated with maxillary hypoplasia due to disruption of growth centers and scar tissue formation.1 However, the long-term effect of adjunctive nonsurgical manipulation has received minimal attention. From the Division of Plastic and Reconstructive Surgery, University of California Los Angeles David Geffen School of Medicine; and Section of Orthodontics, University of California Los Angeles School of Dentistry. Received for publication June 4, 2013; accepted August 7, 2013. Presented at the 92nd American Association of Plastic Surgeons Meeting, in New Orleans, Louisiana, April 20 through 23, 2013, and the 58th Plastic Surgery Research Council Meeting, in Santa Monica, California, May 2 through 4, 2013. Copyright © 2014 by the American Society of Plastic Surgeons DOI: 10.1097/01.prs.0000436857.63021.f0
Cleft patients in developed countries undergo multiple years of orthodontia, usually beginning around the age of 6, with completion only at full skeletal maturity. One of the largest orthodontic movements involves the technique of canine substitution, in which a hemi-arch of dentition beginning with the canine is moved anteriorly to close the dental space left by a cleft-related missing lateral incisor. Disclosure: The authors have no financial interests, including products or devices, associated with this article. There are no commercial associations that might pose or create a conflict of interest with information presented in this article. All sources of funds supporting the completion of this article are under the auspices of the University of California Los Angeles.
Plastic and Reconstructive Surgery • February 2014 Treatment options for dental spaces in cleft lip and palate–related dental agenesis can be divided into three modalities: orthodontic dental space closure, dental space preservation with prosthetic placement, and dental space closure during orthognathic surgery. The decision to close a dental space versus allow a space to remain patent is usually made by the treating orthodontist in consultation with the plastic surgeon, taking into consideration function, facial aesthetics, and social circumstance. All three modalities for closure have their respective advantages and disadvantages. The major advantage of using dental implants is that the normal quantity of dentition in the correct positions can be achieved with an aesthetic result. However, dental implants require adequate bone stock within the cleft space, which may result in multiple rounds of alveolar bone grafting until the bone stock is adequate. Unlike native teeth, dental implants are immobile and thus cannot be subjected to future orthodontic movements if such circumstances are necessary. Both the cost and longevity of dental implants in cleft patients may be deterrents for universal use.2,3 Closure of spaces using canine substitution allows for adequate, although not necessarily perfect, aesthetic results (Fig. 1). Although this technique does not restore dentition to normal quantities or normal positions, functional deficiencies have not been reported if the original presenting malocclusion had a class I or class II skeletal jaw relationship. The major benefits of using this technique are that the maneuver is permanent, uses only vascularized autologous
tissues, and presents no additional cost to the cleft patient who is already undergoing orthodontic treatment. Finally, surgical closure is also an option in patients who require orthognathic surgery and have not had their lateral incisor space closed. In this study, we investigated our institutional experience with canine substitution in cleft lip and palate patients. We report an association between canine substitution and Le Fort I advancement.
PATIENTS AND METHODS Patients Patients with any type of cleft lip or palate evaluated and treated at the University of California Los Angeles Craniofacial Clinic between 2008 and 2012 were identified (n = 95). Patients older than 15 years of age (at or near skeletal maturity) were retrospectively reviewed for general demographic information as well as cleft type, missing teeth, and orthodontic canine substitution, using evaluations and photography at our multidisciplinary University of California Los Angeles Craniofacial Center, orthodontic clinic, and plastic surgery offices. Absence or presence of surgical maxillary advancement or recommendation for orthognathic surgery was recorded. Due to patient compliance and insurance approval issues, the population of patients who received the recommendation for orthognathic surgery during team evaluation and those who received surgery were not the same. For our study, we recorded those patients who required a Le Fort I advancement
Fig. 1. Treatment of lateral incisor agenesis with canine substitution. Lateral incisor agenesis occurs frequently in cleft patients and can be treated either by leaving a patent space (above) or by closure of the space with canine substitution (below). In the latter technique, the entire cleft-side dental arch is anteriorly transposed.
Volume 133, Number 2 • Maxillary Hypoplasia for optimal occlusion based on orthodontic, surgical, and team recommendations. Lateral Cephalometric Analysis Lateral cephalograms obtained using the University of California Los Angeles dental radiology protocol were traced by two independent evaluators. Sagittal relationships to the skull base and mandible were determined using Steiner’s analysis. Relative maxillary vertical height was estimated using the upper facial height (nasion to A point) to lower facial height (A point to menton) ratio. Statistical Analysis All statistical analyses were performed using Stata software (Stata Corp., College Station, Texas). The primary outcome variable was maxillary hypoplasia, defined by cephalometric measurements and the clinical recommendation for orthognathic surgery. Chi-square tests were used to compare the presence of missing teeth and canine substitution on surgery and three cephalometric measurements. Independent sample t tests were used to compare the average cephalometric measurements between patients with and without dental agenesis or canine substitution. Chisquare and t tests were considered significant for p < 0.05. Significant variables were subjected to stepwise logistic regression analyses to determine independence.
RESULTS Patients and Descriptive Statistics Ninety-five patients were evaluated at or near skeletal maturity, with an average age of 18.1 years (range, 15 to 24 years) (Table 1). There were 64 male patients (67.4 percent) and 31 female Table 1. Demographics Value Mean age, yr (range) Male, no. Cleft type, no. Isolated cleft palate Cleft lip and palate Unilateral cleft lip and palate Right Left Bilateral cleft lip and palate Dental agenesis, no. Space preservation, no. (% of dental agenesis) Orthodontic space closure, no. (% of dental agenesis) Surgical patients, no. Age at surgery, yr (range)
18.1 (15–21) 64 (67.4%) 10 (10.5%) 85 (89.5%) 65 (68.4%) 25 (26.3%) 40 (42.1%) 20 (21.1%) 65 (68.4%) 38 (58.5%) 27 (41.5%) 51 (53.7%) 17.8 (15.4–21)
patients (32.6 percent). Patients carried the diagnoses of isolated cleft palate (10.5 percent), unilateral cleft lip and palate (68.4 percent), or bilateral cleft lip and palate (21.1 percent). A total of 68.4 percent were found to have agenesis of one or more teeth, and 96.9 percent of them were missing one or more lateral incisors and 30.7 percent were missing multiple teeth. Among patients who were missing teeth, 58.5 percent had dental space preservation and 41.5 percent had dental space closure by means of orthodontic canine substitution. The comparison of these two groups is outlined below. Le Fort I maxillary advancement was performed or recommended in 53.7 percent of the patients. Le Fort I Advancement in Dental Agenesis versus Canine Substitution Stratification based on dental agenesis and clinical recommendations for Le Fort I advancement was performed on the patient cohort (Fig. 2 and Table 2). In patients without dental agenesis, Le Fort I advancement was required in 20 percent. By contrast, 45 patients (69.2 percent) with dental agenesis required Le Fort I advancement (p < 0.00001). All except one of these patients had at least one missing lateral incisor. In the one outlier patient, the missing central incisor space was closed with substitution starting at the adjacent lateral incisor position, analogous to cuspid substitution. Absence of multiple teeth did not reach statistical significance as a correlate or predictor for Le Fort I advancement. Further evaluation of patients with dental agenesis (n = 65) was performed. Within this cohort, Le Fort I advancement was required in 55.3 percent of patients with patent dental spaces. By contrast, 88.9 percent of patients with canine substitution required Le Fort I advancement (p = 0.004). Maxillary Hypoplasia in Dental Agenesis and Canine Substitution The differences found in our cohort on clinical recommendations for orthognathic surgery prompted us to confirm our findings with objective data for maxillary hypoplasia using cephalometric analyses (Fig. 3). Sagittal maxillary relationships were defined using three measurements: the anterior-posterior relationship of the maxilla to the skull base (SNA; normal range, 78 to 86 degrees), the anterior-posterior relationship of the maxilla to the mandible (ANB; normal, +2 degrees), and the ratio of the vertical height of the upper face (N-A) to the vertical height of the lower face (A-menton) (UFH/LFH; normal range, 0.95 to 1.0 mm) (Table 3).
Plastic and Reconstructive Surgery • February 2014
Fig. 2. Le Fort I advancement in skeletally mature cleft patients. Schematic of patient cohort included in this report is shown. Eighty-nine percent of patients undergoing canine substitution proceeded to Le Fort I advancement.
In comparing patients with and without dental agenesis, SNA averaged 79.4 degrees (range, 74.0 to 84.5 degrees; normal, 82 ± 3 degrees) in patients without dental agenesis. By contrast, SNA averaged 77.2 degrees (range, 66.5 to 83.7 degrees) in patients with missing teeth. Likewise, ANB was also decreased in patients with missing teeth (mean, −3.7 degrees; range, −20.5 to 9.5 degrees; normal, 3 ± 2 degrees) in comparison to patients without missing teeth (mean, 0.9 degrees; range, −5.0 to 6 degrees). Comparison of differences between SNA and ANB using the t test found that both were significant (p = 0.048 and 0.004, respectively). Maxillary vertical height did not differ significantly between the groups (p = 0.193). In comparing patients with and without canine substitution, SNA averaged 79.0 degrees (range, 74.0 to 84.5 degrees) in patients without canine substitution. By contrast, SNA averaged 75.2 degrees (range, 66.5 to 79 degrees) in patients with canine substitution. ANB was also decreased in patients with canine substitution (mean, −5.0 degrees; range, −12.8 to 9.5 degrees)
in comparison to patients without patent dental spaces (mean, −1.1 degrees; range, −20.5 to 6.6 degrees). Comparison of differences between SNA and ANB using the t test found that both differences were significant (p = 0.006 and 0.049,
Table 2. Le Fort I Advancement in Dental Agenesis and Canine Substitution
Fig. 3. Cephalometric measurements. Maxillary relationships were examined using three cephalometric measurements. The sella-nasion-A point angle (SNA; reference range, 79 to 85 degrees) was used to determine the anteroposterior relationship of the maxilla to the skull base. The A point–nasion–B point angle (ANB; reference range, 0 to 3 degrees) was used to determine the anteroposterior relationship of the maxilla to the mandible. The upper facial height:lower facial height ratio (UFH/LFH; reference range, 0.95 to 1.0) was used to estimate the relative vertical height of the maxilla to the face. S, sella; N, nasion; A, A point; B, B point; Me, menton.
Without missing teeth With missing teeth 30 (31.6%) 65 (68.4%) 24 (80%) 20 (30.8%)