Int..L Oral Maxillofac. Surg. 1995; 24:396-400 Printed in Denmark. All rights reserved
MaxillofacialSurgery ISSN 0901-5027
Aesthetic and reconstructivesurgery
Craniofacial growth in bilateral cleft lip and palate patients following secondary premaxillary setback
Rodrigo O. M. Marinho 1, Astrid M. R. Schock 2, John D. Langdon 1, Glyn Wreakes 2 1Departmentof Oral and Maxillofacial
Surgery, King's College School of Medicine and Dentistry, London; 2Department of Orthodontics, Royal Surrey County Hospital, Guildford, UK
R. O. M. Marinho, A. M. R. Schock, J. D. Langdon, G. Wreakes: Craniofacial growth in bilateral cleft lip and palate patients following secondary premaxillary setback. Int. J. Oral Maxillofac. Surg. 1995; 24: 396--400. 9 Munksgaard, 1995 Abstract. Data of an experimental group of bilateral cleft lip and palate patients (BCLP) who had undergone premaxillary setback at a mean age of 10.2 years were compared with a control group of standard cephalometric values for the white population, and with cephalometric data of BCLP patients from the Oslo Cleft Lip and Palate Archive who did not have premaxillary setback. Cephalometric lateral skull radiographs were taken at a mean age of 16.6 years when most facial growth is completed. Overall, the most marked difference between the two cleft samples was a slightly more concave profile in the experimental BCLP group, mainly due to clockwise rotation of the maxillary plane. Other differences were a longer face and a larger mandible in the experimental group.
The range of results for surgical repair of cleft lip and palate is immense. Many questions related to facial growth are not yet answered, due to difficulties in research, which include lost or incomplete files, as well as small patient samples. Cephalometric analysis data of bilateral cleft lip and palate patients from the Oslo Cleft Lip and Palate Archive 18were therefore used for comparison. These are probably the most significant and accurate data available in the literature. Premaxillary protrusion, a characteristic of some infants with complete bilateral cleft lip and palate (BCLP), is a major problem in surgical rehabilitation. Among the procedures advocated to deal with this problem is premaxillary setback, designed to facilitate lip repair (in the case of early setback) and to fit the premaxilla into the maxillary arch form, improving the aesthetics, and facilitating orthodontic treat-
ment, especially if alveolar bone grafts are carried out at the same time 3 (Figs. 1~,). Two types of setback are distinguished depending on the age at which surgery is performed 8. Early premaxillary setback (EPS) is done before or at the same time as lip repair. Late premaxillary setback (LPS) is done after lip closure and generally after palatal repair. Both EPS and LPS may have adverse effects on facial growth in comparison with other BCLP subjects who do not undergo such surgery. However, few studies in the literature confirm such theories, especially in relation to LPS. According to FRIEDE& PRUZANSKV8, EPS was repopularized in the 1950s, mainly by BROWNE & CRONIN. EPS has been criticized in the literature for its negative effects on mid facial growthl,4.7.8,20. HAYWARD~t stated that surgical retrusion of the premaxilla
Key words: cleft lip and palate; craniofacial growth; premaxilla; cephalometry; bilateral cleft lip and palate. Accepted for publication 7 July 1995
would interfere with both blood supply and natural growth and that EPS may cause bony atrophy and disturb dental development. This concern is related to disturbances of the vomeropremaxillary suture (VPS), considered to be a growth centre 6. The VPS, in cases of complete BCLR is a significant suture, allowing rapid growth in the early postnatal months. Traumatic surgical interference may impair suture growth and lead to midfacial retrusion 6. It has been reported t's,2~ that early surgical manipulation of the premaxilla significantly affects the anteroposterior position of the maxilla. There are few reports about LPS and even fewer considering its effect on facial growth. FRIEDE & PRUZANSKY7'8 studied the effect on facial growth of both types of premaxillary setback in patients with complete BCLP and concluded that setback of the projecting
Late premaxillary setback
Fig. 2. Preoperative occlusion view.
Fig. 1. Preoperative profile view.
that of other B C L P patients of similar age treated without setback, with the average profile reaching the normal value for subjects without cleft in early adulthood 8.
Material and Methods premaxilla, whether done in infancy or later, usually resulted in a concave profile. It has been recommended that premaxillary surgery be delayed as long as possible, at least until 7 or 8 years of age, in order to minimize the untoward effects on development of the middle third o f the face 1. According to F ~ I HO~R et al. 3, at that age, the additional disturbance of growth by the operation has probably only a minimal negative influence on the position of the maxilla. The position of the premaxilla immediately after surgery should correspond to
Fig. 3. Postoperative profile view.
The material for this study consisted of the following: 1) an experimental group of 10 subjects lateral skull cephalometric radiographs drawn from the files of BCLP patients who attended the orthodontic department of Queen Mary's Hospital, Roehampton, London, and who had undergone LPS 2) standard cephalometric values for the white population 17 3) cephalometric analysis data of BCLP patients from the Oslo Cleft Lip and Palate Archive who did not have premaxillary setback TM. To be included in the experimental group, the patient must have fulfilled all the following criteria: 1) repaired complete BCLE which was not part of an established syndrome and not associated with any other congenital malformation 2) premaxillary surgical setback via a vomerine section, when patients were be-
Fig. 4. Postoperative occlusion view.
tween 8 and 13 years of age, by a single surgeon (J.D.L.) 3) the presence of a cephalometric radiograph at the age of 16 or over. Each radiograph was taken in centric occlusion and was of sufficient radiographic quality for identification of landmarks. 4) Caucasian origin. Ten cases were obtained which fulfilled the above criteria, forming a group comprised of six boys and four girls. Since there was no statistical difference between the two sexes and also because of the small sample size, the results were pooled. The subjects were studied at a mean age of 16.6 years, when most craniofacial growth would have occurred. The linear and angular measurements used in this study are shown in Figs. 5 and 6, respectively.
Results Some of the results found in this study are presented in tables of linear (Tables 1 and 2) and angular (Tables 3 and 4) measurements with their mean values and standard deviation. All angular measurements are stated in degrees and linear measurements in millimetres.
M a r i n h o et al.
Both B C L P groups presented with smaller maxillary length (Ss'-Ptm) values than the control noncleft group, the difference being smaller in the experimental setback group. A decreased maxillary length value for B C L P groups when compared with a n o r m a l population has been reported in the literature 2,2~ VARGERVIK 20 found smal-
ler values for B C L P nonsetback subjects and even smaller values for the B C L P setback patients when compared with standards. A much larger and significant difference for the variable AnsPns was found in the Oslo group when compared with the experimental group, a finding which is difficult to explain. For this variable, some controversy exists in the literature. As in the present study, DA~-IL2 reported a slightly smaller
Table 1. Linear variables: experimental group vs control group (measurements in millimetreS)
Fig. 5. Linear measurements.
Ss'-Ptm Ans-Pns Pog-Ar N-Me N-Ans Ans-Me
52.4 56.4 114.4 132.1 57.4 77.1
4.2 6.6 6.7 9.5 4.2 4.6
58.8 59.3 119.4 130.0 57.7 74.4
3.9 4.1 5.0 6.5 3.0 5.7
*** ~NS * NS NS NS
Ss': point A perpendicular to maxillary plane.
Table 2. Linear variables: experimental group vs Oslo group (measurements in millimetres)
Ss'-Ptm Ans-Pns Pog-Ar N-Me N-Ans Ans-Me
52.4 56.4 114.4 132.1 57.4 77.1
4.2 6.6 6.7 9.5 4.2 4.6
47.7 67.2 107.8 125.4 52.3 74.6
3.3 5.5 6.5 7.0 4.3 5.5
*** ** ** ** ** NS
Table 3. Angular variables: experimental group vs control group (measurements in degrees)
Experimental Fig. 6. Angular measurements. 1) N-S-Ba, 2) Ar-Go-Me, 3) S-N-A, 4) S-N-Ans, 5) S-N/ Ans-Ptm, 6) S-N-B, 7) S-N-Pog, 8) A-N-B, 9) S-N/Me-Go, 10) N-A-Pog, 11) Ans-Ptm/ Me-Go.
Student's t-test was used for the intergroup comparisons. For this test, it was assumed that, like the experimental group, the population in the other groups was normally distributed. Values are reported for Student's t-test performed on each variable and the level of statistical significance between the cleft experimental and the other two groups. The levels o f probability and their significance are shown as follows: P > 0 . 0 5 nonsignificant NS 0 . 0 1 < P < 0 . 0 5 probably significant * 0.001
S-N-A S-N-Ans S-N/Ans-Ptm S-N-B S-N-Pog A-N-B N-A-Pog Ans-Ptm/Me-Go
75.2 80.1 11.3 73.5 75.7 1.7 187.9 26.9
5.6 5.5 3.9 4.5 4.8 3.0 6.8 5.0
81.6 87.3 7.5 78.7 79.7 2.9 176.2 24.6
4.0 4.4 2.8 3.1 3.0 2.4 4.6 4.4
*** *** ** *** * NS *** NS
Table 4. Angular variables: experimental group vs Oslo group (measurements in degrees)
S-N-A ' S-N-Ans S-N/Ans-Ptm S-N-B S-N-Pog A-N-B N-A-Pog Ans-Ptm/Me-Go
75.2 80.1 11.3 73.5 75.7 1.7 187.9 26.9
5.6 5.5 3.9 4.5 4.8 3.0 6.8 5.0
75.2 84.0 9.1 74.2 76.2 1.0 182.0 27.9
3.8 3.6 3.6 4.1 4.3 3.0 6.9 5.8
NS * NS NS NS NS *** NS
Late premaxillary setback value for his BCLP sample in relation to normal individuals. In contrast, MUNDAV16 found a larger value for her BCLP group than for her control group. As in most other studies 2,16,2~involving operated BCLP subjects, both S-N-A (maxillary prominence) and SN-Ans (anteroposterior position of the maxilla) angles were found to be smaller in cleft samples since the maxilla is the most affected area in subjects with such deformity, probably because of earlier surgical interventions. In the study of FRIEDE • PRUZANSKYs, although patients with early and late premaxillary setback showed similar results, 14 BCLP subjects with no premaxillary setback presented significantly more convex average values than the other samples. Since none of the subjects in their series had vomer flaps, it is probable that a more convex facial profile may be obtained if vomeroplasty is excluded from the primary surgery TM. However, this is not a uniform finding since centres not using vomer flaps 12'19 have shown similar results to those where a vomer flap has been used 5,~s. Much smaller S-N-A and S-N-Ans values for a primary premaxillary setback group than for a nonsetback group have been reported ~. Both cleft groups showed a larger SN/Ans-Ptm (upper face angulation) than the normal population, probably due to a posteriorly upward-tipped maxillary plane, i.e., a clockwise maxillary rotation 9,x4. Larger S-N/Ans-Ptm and smaller S-N-Arts angles found in the experimental group are possibly due to the downward (clockwise) rotational component of the premaxilla setback, which further tipped the maxillary plane. Increased 12,~9 and decreased ~6 upper facial angulation values have been reported for BCLP subjects when compared with noncleft control patients. The Oslo group presented significantly smaller mandibular length (PogAr) values than the experimental group. Other studies 2'2~ show no difference in the Pog-Ar value when comparing BCLP and normal subjects. A smaller S-N-B (mandibular prominence) found in both cleft groups is substantiated in other studies 1,19. This is probably a "compensation" for a decreased growth of the maxilla 13. Similarly, a smaller S-N-Pog (anteroposterior position of the mandible) in nonsetback BCLP h a s been reported in the literature Ls,19. Thus, a more retrogna-
thic mandible is a constant finding in the BCLP patients when compared with the normal standards. Although not statistically significant, the A-N-B value observed in the experimental group !s about 60% smaller than the value presented in the control group. The values found in the experimental (1.7 ~ and the Oslo (1.0 ~ groups are similar to most of those found in other studies of nonsetback BCLP 12,19. One report s found smaller values for early and late premaxilla setback groups, with the latter showing an inverted relationship between the maxilla and the mandible. However, these authors s found an extremely large value in their nonsetback sample, thus showing a very convex profile. BISrU~RA & OLIN 1 reported a negative A-N-B angle for all their EPS subjects and a positive value for all their nonsetback children. A better anteroposterior relation of maxilla and mandible was found for this study's experimental group when compared with other BCLP subjects who had premaxillary setback l,s. The angle of convexity (N-A-Pog) takes into account the influence of the "chin button", or prominence of pogonion 15. A more concave profile was observed in the experimental group when compared with the Oslo sample. This important difference is probably due to the effect of the premaxillary setback in the experimental group, since the clockwise rotation of the premaxilla during the procedure relocates the maxillary plane in a posterior position. Another factor that may have played a role is the smaller mandibular length in the Oslo sample. A much more concave profile in a BCLP group which had premaxilla surgery, when compared with nonsetback BCLP subjects, has been described 1. The maxillary/mandibular plane angle (Ans-Ptm/Me-Go) presented a larger value for both cleft groups when compared with the control subjects, although the difference was not statistically significant. This was confirmed by MUNDAYx6 and by SMhI-n~L~9, who felt that the larger value found for this variable in his BCLP sample was due to the steep slope of the mandibular body, resulting in hyperdivergency of vertical maxillomandibular relations. Although for the Oslo sample, gnathion (Gn) was used instead of menton (Me), no difference should be expected since the definition of Me (lowest point on the symphysial shadow) used here
and that of Gn (lowest point of the mandibular symphysis) 18 are basically the same. Both experimental (57.3%) and Oslo (58.7%) cleft groups presented slightly larger values for the anterior lower facial height (ALFH) than the control group (56.3%). The experimental group value was just outside the standard deviation for a normal population x~ whereas the Oslo value presented a larger difference. This difference may be due to the downward repositioning (rotation) of Ans during the premaxillary setback in the experimental group. Other authors xJaJ6 confirmed larger A L F H values for both nonsetback and setback BCLP groups than their control groups. Therefore, we found that both cleft groups showed more of a class III relationship, and a retrognathic maxilla and mandible, but with no significant difference between them. Smaller maxillary and mandibular lengths in both cleft groups were also shown, with the mandible being even smaller in the Oslo group, a finding which, together with a more upward (clockwise) rotated maxilla in the experimental group, may explain the more concave profile found in the latter group. Although it leads to a more concave profile, the secondary (late) premaxillary setback operation does not, overall, cause any further adverse effect on the facial growth of BCLP patients. Therefore, it may b e advocated in grossly displaced cases. A repeated longitudinal study with a larger sample number, and in which all the variable aspects can be controlled for, should be undertaken.
Acknowledgment. Financial support from the Brazilian National Research Council (CNPq), grant no. 200549/89-8, made this work possible and is gratefully acknowledged. References
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Prof. J. D. Langdon Oral and Maxillofacial Department King's College Hospital Denmark Hill London SE5 8RX