Abstract
To determine the difference in the effects of facemask with miniplate (FM-MP) anchorage on maxillary protraction in growing cleft patients between unilateral (UCLP) and bilateral cleft lip and palate (BCLP) groups.
The samples consisted of a UCLP group (N = 15, 13 boys and 2 girls; mean age 10.98 years; mean protraction duration 2.37 years) and a BCLP group (N = 15, all boys; mean age 11.42 years; mean protraction duration 2.36 years), who were treated with the same surgical technique (rotation and advancement flap and double opposing Z-plasty) by one surgeon and with FM-MP by one orthodontist. Lateral cephalograms were taken before (T1) and after FM-MP (T2). Fourteen skeletal and dental variables were measured. Independent and paired t-tests were performed for statistical analysis.
There were no differences in mean age and values of variables at the T1 stage and in the duration of protraction between the two groups. The BCLP group showed less advancement of point A than the UCLP group (ΔA-vertical reference plane, 2.51 mm vs 4.06 mm, P < .05; ΔA-N perpendicular, 0.79 mm vs 2.26 mm, P < .05; ΔSNA, 0.45° vs 2.85°, P < .01). Since counterclockwise rotation of the palatal plane in two groups was minimal (−0.36° vs −0.87°), no difference was observed with regard to clockwise rotation of the mandible (0.46° vs −0.07°). There were no differences in the degree of labioversion of the maxillary incisor (8.16° vs 7.10°), linguoversion of the mandibular incisor (−2.66° vs −2.14°), and increase in overjet (5.39 mm vs 5.70 mm) between the two groups.
In FM-MP therapy of growing cleft patients under the conditions of this study, the UCLP group shows a more favorable change in maxillary advancement than the BCLP group.
INTRODUCTION
Cleft patients usually have a maxillary hypoplasia due to postsurgical scar tissues at the lip and palate and/or inherited growth deficiency.1–6 In addition, cleft patients are known to have an increased vertical growth pattern compared to that of noncleft patients1,7–13 and to maintain their initial vertical pattern during growth.14
Facemask therapy for maxillary protraction has been regarded as an effective tool for producing orthopedic change in cleft patients.15,16 Traditionally, several intraoral devices such as the labiolingual arch, quad-helix, and rapid maxillary expansion (RME) appliance have been used as tooth-borne anchorage for facemask.17 Recently, facemask with miniplate (FM-MP) therapy has been reported to maximize skeletal effects while minimizing dental change.18–21
The degree of orthopedic change is known to be affected by several factors, including patient age, growth pattern, amount of postsurgical scar tissue, type of cleft, compliance of subject, types of treatment devices, magnitude and direction of orthopedic force, and duration of protraction therapy.22–25 Therefore, it is necessary to apply strict selection criteria to confine the samples to those with similar patient- and treatment-related conditions, including age, gender distribution, cephalometric characteristics, cleft repair surgery method, protraction method and duration, and orthodontic treatment method.
Tindlund and Rygh26 reported that the treatment results with conventional facemask therapy were different between unilateral (UCLP) and bilateral cleft lip and palate (BCLP) patients. However, there have been few cephalometric studies about the effect of FM-MP on maxillary protraction according to cleft type. Therefore, the purpose of this study was to investigate the difference in the effects of FM-MP on maxillary protraction in growing cleft patients between BCLP and UCLP groups. The null hypothesis was that there was no significant difference between BCLP and UCLP groups in the effects of FM-MP on treatment of maxillary hypoplasia in growing cleft patients.
MATERIALS AND METHODS
This retrospective study was performed under approval from the Institutional Review Board of Seoul University Dental Hospital (IRB: CRI 09025). The initial samples were selected using the following criteria: cleft patient (UCLP and BCLP) in Seoul University National Hospital and Dental Hospital; identical surgical technique performed by one surgeon (Millard's rotation and advancement flap for cheiloplasty, 3 to 5 months after birth; Furlow's double opposing Z-plasty for one-stage palatorrhaphy, 12 to 18 months after birth; no primary gingivoperiosteoplasty); the same FM-MP therapy protocol performed by one orthodontist; availability of treatment records and lateral cephalograms 1 month before (T1) and at least 1 year after FM-MP (T2), less than 14 years of chronologic age, and less than a cervical vertebrae maturation index stage of 3 at the T1 stage. Selection criteria for final samples were as follows: midface hypoplasia (SNA, less than 80°; A-N perpendicular, less than 0 mm), chin point deviation less than 4 mm, good stability of the miniplates throughout facemask therapy, good compliance with facemask therapy, and more than 1 year of FM-MP treatment for orthopedic effects. The final sample of this study consisted of a UCLP group (N = 15, 13 boys and 2 girls; mean age 10.98 ± 1.92 years; mean protraction duration 2.37 ± 1.03 years) and a BCLP group (N = 15, all boys; mean age 11.42 ± 1.86 years; mean protraction duration 2.36 ± 0.89 years) (Table 1).
The protocols of FM-MP were as follows (Figure 1): two curvilinear type surgical miniplates (KLS Martin, Tuttlingen, Germany) were placed in the infrazygomatic crest area, one on either side, under local anesthesia. The end of the miniplate was exposed through the buccal attached gingiva between the maxillary canine and the first premolar or the maxillary primary canine and the first primary molar. The end hole of the miniplate was modified to create a hook for elastics. The stability of the miniplates was confirmed 4 to 8 weeks after installation, and the patients were instructed to wear a Petit type facemask (Gwangmyung, Seoul, Korea) for 12 to 14 hours per day. The orthopedic traction force (more than 500 g/side) was applied with forward and 30° downward vector relative to the maxillary occlusal plane. According to a recent prospective randomized clinical trial,27 facemask therapy produced equivalent changes in the dentofacial complex with or without RME. Therefore, an RME appliance was not applied during protraction in all subjects in order to exclude the effect of midpalatal suture opening on maxillary protraction.
Position of the miniplate in the maxilla (A) and the buccal attached gingiva (B).
Position of the miniplate in the maxilla (A) and the buccal attached gingiva (B).
In the lateral cephalograms taken at the T1 and T2 stages, the landmarks, reference planes, and 14 skeletal and dental variables were defined (Figures 2 and 3). Cephalometric tracing and measurements were performed by a single operator using the V-Ceph program (CyberMed, Seoul, Korea) in the units of 0.05° and 0.05 mm. All variables from five randomly selected subjects were reassessed by the same operator after 2 weeks. The differences ranged from 0.27 to 0.38 mm for the linear measurements and from 0.31° to 0.48° for the angular measurements according to the Dahlberg formula.28 Therefore, the first set of measurements was used for this study. After Shapiro-Wilk normality test, paired t-test within each group and independent t-test between two groups were performed for statistical analysis.
Landmarks and reference planes. Landmarks: 1. Nasion. 2. Sella. 3. Orbitale. 4. Porion. 5. Anterior nasal spine. 6. Posterior nasal spine. 7. Point A. 8. Maxillary central incisor edge. 9. Maxillary central incisor root apex. 10. The mesiobuccal cusp tip of the maxillary first molar. 11. Mandibular central incisor edge. 12. Mandibular central incisor root apex. 13. Point B. 14. Menton. 15. Gonion. Reference planes: horizontal reference plane, a horizontal line which angulated 7° clockwise to the sella-nasion line passing through the sella; vertical reference line, a perpendicular plane to the horizontal plane passing through the sella.
Landmarks and reference planes. Landmarks: 1. Nasion. 2. Sella. 3. Orbitale. 4. Porion. 5. Anterior nasal spine. 6. Posterior nasal spine. 7. Point A. 8. Maxillary central incisor edge. 9. Maxillary central incisor root apex. 10. The mesiobuccal cusp tip of the maxillary first molar. 11. Mandibular central incisor edge. 12. Mandibular central incisor root apex. 13. Point B. 14. Menton. 15. Gonion. Reference planes: horizontal reference plane, a horizontal line which angulated 7° clockwise to the sella-nasion line passing through the sella; vertical reference line, a perpendicular plane to the horizontal plane passing through the sella.
(A) Linear variables. 1. A-N perpendicular (mm). 2. A-N perpendicular (mm). 3. Overbite (mm). 4. Overjet (mm). (B) Angular and proportion variables. 5. Bjork sum (°) = a + b + c. 6. SNA (°). 7. SNB (°). 8. ANB (°). 9. U1-FH (°). 10. SN to palatal plane angle (°). 11. SN to occlusal plane angle (°). 12. SN to mandibular plane angle (°). 13. IMPA (°). 14. Anteroposterior facial height ratio = (e/d) × 100.
(A) Linear variables. 1. A-N perpendicular (mm). 2. A-N perpendicular (mm). 3. Overbite (mm). 4. Overjet (mm). (B) Angular and proportion variables. 5. Bjork sum (°) = a + b + c. 6. SNA (°). 7. SNB (°). 8. ANB (°). 9. U1-FH (°). 10. SN to palatal plane angle (°). 11. SN to occlusal plane angle (°). 12. SN to mandibular plane angle (°). 13. IMPA (°). 14. Anteroposterior facial height ratio = (e/d) × 100.
RESULTS
Characteristics of the Samples
There were no significant differences between the BCLP and UCLP groups with regard to mean age at the T1 stage (11.42 years vs 10.98 years), gender distribution (all boys vs 13 boys and 2 girls), and duration of protraction (2.36 years vs 2.37 years) (Table 1). All patients in both groups received orthodontic treatment simultaneously with FM-MP treatment (fixed orthodontic appliance on the maxillary arches during FM-MP treatment, 100.0% [15/15] in the UCLP group and 93.3% [14/1] in the BCLP group; removable orthodontic appliance for expansion of the maxillary arch, 6.7% [1/15] in the BCLP group). Six patients in the UCLP group (40.0%) and five patients in the BCLP group (33.3%) received fixed appliances on both the maxillary and mandibular arches. Therefore, the distribution of orthodontic appliances on the maxillary or mandibular arch was not significantly different between the two groups. In addition, the skeletal and dental variables at the T1 stage were not significantly different between the two groups (Table 2).
Changes in the Skeletal and Dental Variables Within Each Group
In the BCLP group, there were significant increases in ΔA-VRP (2.51 mm, P < .001), ΔA-N perpendicular (0.79 mm, P < .05), and ΔANB (1.27°, P < .05) (Table 3). Since counterclockwise rotation of the palatal plane (Δpalatal plane angle, −0.36°) was minimized and clinically insignificant, the BCLP group did not show a significant clockwise rotation of the mandible (Δmandibular plane angle, 0.46°) and change in vertical dimension (Bjork sum, 0.48°). Labioversion of the maxillary incisor (ΔU1-FH, 8.16°, P < .01) contributed to increase in Δoverjet (5.39 mm, P < .001), while linguoversion of the mandibular incisor was insignificant (ΔIMPA, −2.66°).
Comparison of the Amounts of Change in the Skeletal and Dental Variables Between T1 and T2 Stages Within Each Group and Between the Two Groups

The UCLP group showed significant increases in ΔA-VRP (4.06 mm, P < .001), ΔA-N perpendicular (2.26 mm, P < .01), ΔSNA (2.85°, P < .001), and ΔANB (2.84°, P < .01). Similar to the BCLP group, the UCLP group did not show significant clockwise rotation of the mandible (Δmandibular plane angle, −0.07°) and change in vertical dimension (Bjork sum, −0.07°) due to minimal counterclockwise rotation of the palatal plane (Δpalatal plane angle, −0.87°). Labioversion of the maxillary incisor (ΔU1-FH, 7.10°, P < .01) caused a significant increase in overjet (Δoverjet, 5.7 mm, P < .001), although linguoversion of the mandibular incisor (ΔIMPA, −2.14°) was not significant.
Comparison of the Amounts of Change in the Skeletal and Dental Variables Between the Two Groups
As Table 3 shows, advancement of point A was less pronounced in the BCLP group than in the UCLP group (ΔA-VRP, 2.51 mm vs 4.06 mm, P < .05; ΔA-N perpendicular, 0.79 mm vs 2.26 mm, P < .05; ΔSNA, 0.45° vs 2.85°, P < .01).
Since the amount of counterclockwise rotation of the palatal plane in the two groups was negligible (Δpalatal plane angle, −0.36° vs −0.87°), no significant differences in the amounts of clockwise rotation of the mandible (Δmandibular plane angle, 0.46° vs −0.07°) and change in vertical dimension (Bjork sum, 0.48° vs −0.07°) were observed. In addition, there were no significant differences in the amount of labioversion of the maxillary incisor (ΔU1-FH, 8.16° vs 7.10°), linguoversion of the mandibular incisor (ΔIMPA, −2.66° vs −2.14°), and increase in Δoverjet (5.39 mm vs 5.70 mm) between the two groups.
DISCUSSION
Since the primary purpose of this study was to compare the effectiveness of FM-MP therapy for treatment of maxillary hypoplasia between BCLP and UCLP patients, the authors tried to apply strict selection criteria so that two groups had similar patient- and treatment-related conditions (Table 1). Lateral cephalograms and superimposition between T1 and T2 stages representing each group were manifested (Figure 4).
Lateral cephalograms at T1 and T2 stages, and superimposition between T1 and T2 stages. (A) An example of the BCLP group (duration of protraction, 2.33 years; increase of ΔA-VRP, 2.35 mm), (B) An example of the UCLP group (duration of protraction, 1.67 years; increase of ΔA-VRP, 4.10 mm).
Lateral cephalograms at T1 and T2 stages, and superimposition between T1 and T2 stages. (A) An example of the BCLP group (duration of protraction, 2.33 years; increase of ΔA-VRP, 2.35 mm), (B) An example of the UCLP group (duration of protraction, 1.67 years; increase of ΔA-VRP, 4.10 mm).
In cases of untreated noncleft Class III patients with maxillary hypoplasia, Shanker et al.29 reported that point A advanced only 0.2 mm over a 6-month period. According to a meta-analysis, Kim et al.30 reported that point A advanced between 0.9 and 2.9 mm in facemask therapy for Class III patients.
In the present study, although both groups showed significant increases in ΔA-VRP (BCLP group, 2.51 mm, P < .001; UCLP group, 4.06 mm, P < .001) and ΔA-N perpendicular (BCLP group, 0.79 mm, P < .05; UCLP group, 2.26 mm, P < .01), the advancement of point A in the UCLP group was significantly larger than that in the BCLP group (ΔA-VRP, P < .05; ΔA-N perpendicular, P < .05) (Table 3). In addition, increase in ΔSNA was only significant in the UCLP group (2.85°, P < .001) (Table 3). Considering that the protraction durations were similar in both groups (2.36 years in the BCLP group vs 2.37 years in the UCLP group) (Table 1), the results of this study indicate that the maxilla of the BCLP group was less advanced than that of the UCLP group. Treatment efficiency of maxillary advancement (defined by increase of ΔA-VRP/duration of protraction) was 1.07 ± 0.64 mm/y in the BCLP group and 1.75 ± 0.67 mm/y in the UCLP group, respectively. These findings are in accordance with Tindlund and Rygh,26 who reported that maxillary advancement with a conventional tooth-borne anchorage facemask was greater in UCLP patients than in BCLP patients.
Postsurgical scar tissue on the lip and palate might inhibit the maxillary growth.31 Since BCLP patients usually have more scar tissue than UCLP patients, the amount of scar tissue may be one reason for the difference in maxillary advancement between BCLP and UCLP patients. Therefore, further study is needed to quantify the influence of cleft scar tissue on maxillary advancement.
In facemask therapy with tooth-borne anchorage, several studies32–34 have reported counterclockwise rotation of the maxilla, clockwise rotation of the mandible, and increase in lower facial height. In the present study, counterclockwise rotation of the maxilla was clinically insignificant in both groups (Δpalatal plane angle, BCLP group, −0.36°, UCLP group, −0.87°) (Table 3). Because cleft patients have more vertical growth pattern than do noncleft patients,11 counterclockwise rotation of the maxilla should be minimized in cases with vertical growth pattern.
In addition, in the present study, neither the BCLP nor UCLP group demonstrated significant changes in anteroposterior facial height ratio (ΔA/P FHR, BCLP group, 0.58, UCLP group, 0.66) and mandibular plane angle (Δmandibular plane angle, BCLP group, 0.46°, UCLP group, −0.07°) (Table 3). These findings suggest that clockwise rotation and vertical dimension change of the mandible in cleft patients were minimized through the use of FM-MP.
Maxillary protraction with tooth-borne anchorage in cleft patients has been reported to induce dental effects, specifically, labioversion of the maxillary incisors and linguoversion of the mandibular incisors.12,35 Since miniplates are independent of the maxillary dentition, it was expected that FM-MP therapy would minimally influence the maxillary incisors. In this study, all subjects were treated with fixed appliances in the maxillary arch in order to align the maxillary dentition and to regain space for congenitally missing maxillary lateral incisors and alveolar bone graft. Although there was no significant difference in the amounts of labioversion of the maxillary incisors between the two groups, labioversion of the maxillary incisors was more pronounced in the BCLP group than in the UCLP group (ΔU1-FH, 8.16° vs 7.10°) (Table 3). More labioversion of the maxillary incisors in the BCLP group than the UCLP group would contribute similar increase of overjet in both groups despite the difference in the amount of maxillary advancement. Further investigation is required in the subjects who were treated with only FM-MP without a fixed appliance in order to objectively determine the effect of treatment on the maxillary incisors.
On the contrary, changes in the mandibular incisors in the present study were in accordance with the results of a previous study of facemask treatment with tooth-borne anchorage.34 In both groups, the mandibular incisors were tipped lingually but statistically insignificant (ΔIMPA, BCLP group, −2.66° vs UCLP group, −2.14°) (Table 3).
Although the authors applied strict selection criteria to include subjects with similar pretreatment conditions (age-, gender-, and facial pattern-matched samples), the findings of this study should be interpreted with caution due to the relatively small sample size and absence of the untreated cleft controls. In addition, it would be of great interest to evaluate further the effect of FM-MP with respect to various factors, such as cleft type, soft tissue scar, force vector, magnitude of orthopedic traction force, and patient age.
CONCLUSION
Although FM-MP therapy was effective for protracting the maxilla in both the BCLP and UCLP groups, the UCLP group showed a more favorable change in maxillary advancement than the BCLP group.