Occlusion, arch dimensions, and craniofacial morphology after palatal surgery in a group of children with clefts in the secondary palate

Amemkan Journal of ORTHODONTICS Volume 76, Number 3

ORIGINAL

September, 1979

ARTICLES

Occlusion, arch dimensions, and craniofacial rnoyphology after palatal surgery in a, group of children with clefts in the secondary palate Gunnar Jonsson, D.D.S., and Birgit Thilander, D.D.S., Odont.D.* Urn& and Gothenburg,

Sweden

I n children

with clefts in the palate only (CPO), the maxillofacial skeleton shows a retrognathia in relation to the cranial base. 3, 4, 8, 20,p2 This retrognathia depends on a shortening and posterior displacement of the maxilla and the mandible. There is also a reduced posterior facial height due to an increased angle between the cranial and the mandibular bases. The individual variations in this pattern are great. A comprehensive survey of the pertinent literature of CPO has been made by Ross and Johnston.‘l It is their opinion that the retrognathic face represents an interference in maxillary growth which is a long-term effect of the scar tissue created by the palatal surgery. It has also been suggested that the aberrant craniofacial morphology in CPO persons as compared to normal persons may be attributed not only to surgery but also to a morphogenetic characteristic of the cleft palate face.2a 2o Only a few studies on arch dimensions and occlusion in CPO persons appear in the literature. These variables seem to be influenced b:y the size of the cleft,g and the type of surgery, and time of surgical intervention.i2 The frequency of cross-bite occlusion varies among different investigations and different surgical techniques but is generally higher than in healthy children of the same age. la6, 8-1o, I43lg, 24Our clinical impression of the CPO children who were operated upon by a modified von Langenbeck procedure in the Department of Plastic Surgery of the University of Umed was that the frequency of cross-bite occlusion was rather low. The aim of the present investigation was, therefore, to study the occlusion, arch dimensions, and craniofacial morphology in a group of CPO children who were operated From the Departments of Orthodontics, University of Urn& and University of Gothenburg. This study was supported in part by grants from the Swedish Dental Society. *Professor and Head of the Department of Orthodontics, University of Gothenburg. 0002.9416/79/090243+13$01.30/0

0

1979 The C. V. Mosby CO

243

244

Jonsson

und

iim. i. OrthoLi. September 1979

Thilutxkr

PaMe i. Distribution of chiMren in the stuciyaccording IO type of cleft, sex, and type 3f surgery

GroupSP GroupHSP Total

13

13 26

!3 16 5

26 29 55

I (27%) 26 (90%) 33 (60%)

19 (73%) 3 (10%) 22 (40%)

-

upon by a modified von Langenbeck procedure. The occlusion and arch dimensions were studied from the time of deciduous dentition to that of the late mixed dentition (upper canines and second premolars not fully erupted). The craniofacial morphology was assessed at 10 to 11 years of age. Material,

methods

and patients

The material consists of all children with clefts of the secondary palate as their only known anomaly, born between 1960 and 1972, and operated upon by a modified von Langenbeck procedure at the Department of Plastic Surgery, University Hospital, Umeb. The fifty-five children included in the study were divided into two groups according to the degree of the clefts: children with clefts in the soft palate (SP) and children with clefts in the hard and soft palate (HSP) (Table I). Children with submucous clefts were not included in the study. Study casts of the maxilla, photographs, and medical records were used as a basis for grouping the children. Analyses were made of study casts from the ages of 4 to 11 years and lateral roentgenocephalograms taken at 10 or 11 years of age (Fig. 1). Among the 55 children, there were 21 (11 SP and 10 HSP) for whom dental casts were available at all three age periods: 4 to 6, 7 to 9, and 10 to 11 years. In. these children a longitudinal study was made to determine whether their occlusion differed from that in the material as a whole, which is a mixed longitudinal study. If more than three sets of dental casts had been made during the ages from 4 to 11 years, those made at 5, 8, and 11 years of age, respectively, were used in the analyses. Deciduous teeth were ground to eliminate forced guidance in 2 children with unilateral cross-bite, and permanent teeth were extracted to eliminate crowding in 8 of the 5.5 children. These were the only orthodontic treatments given during the observation period from 4 to 11 years of age. Surgical

procedures

The palatal surgery was performed as a modified von Langenbeck palatoplasty. The mean age at surgery was 1 year 9 months (range, 1 year 4 months to 2 years 10 months). The nasal and oral mucoperiosteum was separated by an incision along the margin of the deft. The nasal and oral mucoperiosteum was gently elevated. The hamulus and the palatine artery were preserved. A submucous dissection of the muscles in the soft palate was made. If the cleft could not be closed without heavy tension of the flaps, bilateral relaxing incisions were made medial to the alveolar processes. In 22 children (40 percent) closure was performed without relaxing incisions (Table I). The nasal and oral mucosa was closed with figure-of-eight sutures in the hard palate and in the anterior three fourths of the soft palate. In the posterior part of the soft palate, single sutures were used. (The patients were operated upon by Dr. S. StenstrGm.)

Volume 16 Number 3

Postoperative

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245

CASE NO.

.

55

. . .

CASEA NO. . *s-

.

. .

.

50

. . .-

. . . .-.

m.

. .-.

. .--.-.

45

.--.

.-.-.

.

.-.-. .-.-.-m .-. .-.-. .-. .-.

IS-

40

.--. .-.-.-. .-.-.-. .-.-.

m-

,’

4

.--.-. .-.--.-.-. e-0

.

.--.-. .-.-0

35

.-.--. . .-.-.-.-.-. .-.-..-.-.

.

.-.-.

5

. .

.

.-. .-. .-. . .-.-.-. .-.-.-.-• .-.-.-.-.-.

5-

.-. . .-.

6

7

30

8

9

10

.

-.-.-.-. 0-0 .

.-.--.-.-.-. .-.-.--. .

.

.-.-.-.

11 AGE

b

a Fig. 1 Distribution of the registrations patients with clefts in the soft palate and soft palate (Group HSP).

of the fifty-five patients (Group SP). Filled circles(b)

in the study. Filled squares (a) indicate indicate patients with clefts in the hard

MANDIBLE

MAXILLA

Fig.

2. Reference

points

and

distances

used

in the cast

analysis

ArW,

Arch

width;

ArL,

Arch

length.

Cast analyses

The study casts used in the present study were made as a part of the recording program for cleft palate patients in our clinic. The occlusion was analyzed using descriptive’8 and numerical” classification systems for the buccal and frontal relations. The lateral incisors and the second permanent molars were never included in the analyses, and the first permanent molars were included only for children 7 years of age or older. If a tooth was missing or had not erupted, it was given a score corresponding to the mean value of the neighboring teeth in the same segment. The scoring of the incisors was modified so that the score was 0 if the overjet was normal or larger. The length and width of the upper and lower jaws were measured on the study casts. The reference points and

Fig. 3.

Reference

points

and planes

used

in the cephalometric

analysis.

distances were the same as those defined by Moorrees” (Fig. 2). The measurements were made to the nearest 0.1 mm. by means of sliding calipers (Mauser). Roentgenocephalometric

measurements

Cephalometric measurements were made on lateral cephalograms of the patients at 10 to 11 years of age. If registrations had been made at the ages of both 10 and 11 years, the registration at age 10 was used. Group SP consisted of 14 patients and Group HSP of 16 patients. The roentgenograms were taken in a cephalostat with a focus-film distance of 155 cm. and a distance of 15 cm. between the median sagittal plane of the object and the film plane. In addition to the traditional reference points and lines according to Bjiirk,7 the following reference points were used: x,-The intersection between the perpendicular to the line NSL through s and the line NL. ss’-The projection of ss on the line NL. The following angles and distances thus were used as variables in the cephalometric investigation: 1. 2. 3. 4. 5. 5.

s-n-ss s-n-sm s-n-pg n-ss-pg n-s-ar IL,-NL

7. 8. 9. 10. Il. 12.

ILi-ML NSL-NL NSL-ML RL-ML ss’-pm xi-pm

(Fig. 3)

The measurements were made on tracing films. The readings were made to the nearest 0. I mm. for the distances and to the nearest 0.5 degree for the angles. Duplicate tracings were made for all pateints, and the mean values of the two readings were used in the final calculations.

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Table II. Occlusion according to descriptive method at different ages for children with clefts in the soft palate (group SP) and for children with clefts in the hard and soft palate (group HSP)

~~ 4 5 6 7 8 9 10 11

18 25 21 21 14 19 24 9

8 9 11 11 6 8 10 3

0 0 0 0 0 1 1 0

9 14 8 8 I I 10 5

1 2 2 2 1 3 3 1

17 23 19 19 13 15 20 8

94 92 90 90 93 79 83 89

1 2 2 2 1 4 4 1

6 8 10 10 I 21 17 11

Table III. Occlusion according to descriptive method in the twenty-one patients in subsample Type of occlusion

No cross-bite Anterior cross-bite Canine cross-bite only Buccal cross-bite Anterior + buccal cross-bite

4-6 years (No.)

7-9 years (No.)

lo-11 years {No.)

19 (90%) 1 1 0 0

19 (90%) 1 1 0 0

18 (86%) 1 0 1 1

The precision of the measurements was determined according to the formula S, = Jy-3

where a, denotes the reading from tracing 1 and a2 denotes the reading from

tracingn2. The range of the precision (S,) varied between 0.4” (s-n-sm) and 1.0” (NLNSL), except for IL,-NL (1.4”) and ILi-ML (1.6”). The precision of the readings thus was considered acceptable as compared to other cephalometric studlIes. Statistical analyses Differences between qualitative variables were tested by means of a &i-square test or, if n < 20, Fisher’s exact probability test. 23 Differences between quantitative variables were tested with Student’s t test. The dependency of occlusion on age was tested by calculating Spearman’s rank corrleation coefficient (rs), which was tested by means of Student’s t test. The null hypothesis was rejected at the 5 percent level. Results Cast analyses. Using the descriptive classification of occlusion, normal anterior and buccal occlusion was found in 79 to 94 percent of the children at the different ages (Table II). The findings were similar for the 2 1 children in the longitudinal subsample (Table III). When the occlusion was analyzed by the numerical classifi’cation, the distribution of the scores was skew in such a way that more than. 50 percent of the children at most age levels had a score of 0. Therefore, the median values (Md) were more representative for

n

8

10

AGE

9

16

11 10

5

4

1110

6

68

7

9

8

10

11 13

9

3

10

6 11

Fig. 4. The distribution, in percent, at different ages of the patients according to numerical classification of occlusion. SP, Children with clefts in the soft palate. HSP, Children with clefts in the hard and soft palate. Filledbars: Percent of children with incisor and buccal score ~0. Open bars: Percent of children with buccal score ~0. Hatched bars: Incisor score CO.

IV. Median vaiues (Md), range (R), and number of casesat each age level for the total occlusal score from 4 to 11 years of age

Table

Children

with clefts

Md R

0

Children R NO.

-3 8

with

Md

softpalate 0

o-,

NO.

in

o-

0 -3

0 -

9 clefts

0 04

-2 IO

in hard

0 -4

II

o+

-3 II

-0.5 O+-6 6

0 04

-9

O-,

0 -10 10

o-,

9

0 -6 11

-2 0 +

-4 3

and soft palate

0 04 -16 16

0 o+

-4 IO

0 0 10

0 o-

-3 8

o+

-1

-13 13

-4

o+

-15 6

the material than the mean values. in the total material the median value for the total occlusal score was 0 at all ages except 11 years, when Md was - 2.5 (Table IV). The same pattern was observed among the 21 children in the subsample with median values of 0 at 4 to 4 years of age and - 1 at IO to 11 years. There was a negative correlation between age and the frequency of cross-bite in the material (rs = -0.76, p < 0.05). There was no significant difference between Groups SP and HSP regarding the incisor score, buccal score, or frequency of children with a total occlusal score of 0 at the different ages (Fig. 4). There was no difference in the frequency of cross-bite between children in whom relaxing incisions were used or those in whom only denudation was made at the palatal closure. For some age groups for one or both of the SP and HSP groups, there were fewer than four dental casts on which measurements could be made. Measurements on the remaining casts were not possible because of the fact that the deciduous teeth had exfoliated and the permanent teeth had not yet erupted. Mean values are presented as representative values, since no extreme values were found in the age groups and there were only small differ-

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249

32-

30-

**-

0 .

ArW 3+3 -II-

GROUP -13-

SP HSP

0 H

ArW 5+5 -,I-

GROUP -(I-

SP HSP

-1 ArW 6+6 -111 A

26-

c-4

GQOUP SP -(3HSP

NONCLEFTS

456789

Fig. 5. Mean values for and first molar (ArW6 + groups were small and, Mean values for normal in the soft palate. HSP,

maxillary arch width in the canine (ArW3 + 3), second premolar (ArWS + 5), 6) regions at different ages. The differences in standard deivations between the for clarity only, the mean values are indicated in this and the following figures. children from Moorrees” are included for comparison. Sf, Children with clefts Children with clefts in the hard and soft palate.

ences between the mean and median values. Testing of the differences between Groups SP and HSP was not considered relevant because of the small sample sizes. With the exception of the width between the first permanent molars (ArW 6 + 6), the measurements of the maxillary arch width showed only slight differences between Groups SP and HSP (Fig. 5). In Group HSP, ArW 6 + 6 decreased 2.7 mm. from the ages of 6 to 11 years, while this width increased 0.9 mm. in Group SP. During the whole period ArW 6 + 6 was larger in Group HSP than in Group SP. The maxillary arch length (ArL) was longer in Group SP than in Group HSP at all registrations except at 8 years of age (Fig. 6). From 4 to 11 years of age, ArL decreased 1.8 mm. in Group SP and 3.3 mm. in Group HSP. If cases with extractions were excluded, ArL increased 0.5 mm. in Group SP and decreased 0.1 mm. in Group HSP (Fig. 6). In the mandible the difference between Group SP and Group HSP was small. ArW 6 - 6 tended to be larger in Group HSP than in Group SP. The mandibular arch length was larger in Group SP than in Group HSP, but at 11 years of age there was no difference in mandibular ArL (Figs. 6 and 7). Roentgenologic data. In Group HSP the maxilla was more retrognathic than in Group SP (Table V). Tbere was a tendency for the maxilla to be shorter (ss’-pm) and more posteriorly located (xl-pm) in Group HSP than in Group SP. The facial profile also tended

Am. 1. Orrhou’. September 1979

;

24L

ArL

GROUP -*.-

SP HSP

4 5 6 7 8

9

10

11AGE

a MANDIBLE

MAXILLA n A

ArL GROUP -II-

SP WITHOUT HSP -11-

EXTRACTIONS -I,-

13 ArL GROUP e -13-

mm, *--

24L b4

e---s

NONCLEFTS

5

,

I 6

7

8

9

10

11 AGE

c4

SP HSP

NONCLEFTS

,

,

,

,

/

I

5

6

7

8

9

10

Fig. 6. Mean values for maxillary and mandibular arch lengths (A$) different ages and maxillary arch length for children with no extractions values for normal children from Moorrees17 are included for comparison.

for the total of permanent

,

b

11 AGE

material teeth

(a, c) at (b). Mean

to be straighter in Group HSP than in Group SP. The angle between the skull base and the nasal line (NSL-NL) was greater, the lower incisors were more retrociined, and the gonion angle (RL-ML) was greater in Group HSP than in Group SP. When compared to healthy children, the children in Group SP and Group HSP were retrognathic. The angle between the line NSL and line NL was greater in both groups as compared to healthy children. Also, in Group HSP the angles NSL-ML and RL-ML were greater and the lower incisors were more retroclined (K-ML) than in healthy children. Discussion

The registration program for cleft paiate patients in the Umel region began in 1960. Et has been modified over the years, and therefore the recordings have not been made at the same age level for all patients. The study was restricted to the period of 4 to 11 years, as only a few patients were older than 11 years at the time of the investigation. The prepubertal growth minimum in

Volume 16 Number 3

Postoperative

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afrer clej palate surgery

251

SP HSP SP HSP SP HSP

Fig. 7. Mean

values

for mandibular

and fkst molar (ArW6 - 6) regions are included for comparison.

arch width

in the canine

(AM3

- 3), second

at different

ages.

values

for normal

Mean

premolar children

from

(ArWS

~ 5),

Moorrees”

the Scandinavian population occurs at about the age of 10 years in healthy girls and in 11.5 years in boys.7 Thus, the effect of the differences between boys and girls in onset of the pubertal growth spurt should not have influenced the results in the present study. Dividing the material into more than two groups on the basis of sex or diagnosis provided no further information, and therefore the present groups were formed. The longitudinal study of the subsample showed the same pattern of occlusal and jaw development as in the total material. The presentation as a mixed longitudinal study, therefore, provides a representative picture of the children who have been operated upon in Umei by the modified von Langenbeck technique. Maxillary arch dimensions are influenced not only by the scar tissue but also by orthodontic treatment involving extractions or expansion of the dental arches. The scar tissue inhibits normal maxillary growth, which leads to crowding of the teeth. As it was not possible to determine the role played by the decreased maxillary growth on the development of crowding in each individual case, cases in which extractions had been performed were included in the study. The transversal maxillary growth in the posterior region seemed to be more influenced by the palatal surgery and the size of the cleft than was the transversal growth in the canine region (Fig. 5). The decrease in the distance between the first maxillary molars in Group HSP from 6 to 11 years in contrast to the pattern in Group SP probably depended on the lingually directed eruption path of the molars in Group HSP. Whether this eruption path depends on the size of the cleft or is an effect of the palatal surgery is difficult to determine, but as the frequency of relaxing incisions was higher in Group HSP than in Group SP (p < 0.001) and the greatest medial displacement of palatal mucoperiosteum occurs in the first molar region, it is not unlikely that this decrease in width was an indirect effect of the surgery. The maxillary arch length also appears to have been influenced by the size of the cleft and the palatal surgery, as ArL

Table

V. Mean

values

(x)

and

standard

cephalometric

analysis

1. s-n-ss 2. s-n-sm

80.8 77.8

2.7 3.2

77.3 75.9

3.2 2.5

3. s-n-pg 4. n-ss-pg 5. n-s-ai6. IL ,-NL 7. &-ML 8. NSL-NL

78.6 176.0

3.4 5.1

77.2 180.2

2.9 5.9

121.6 112.5 91.2 10. I

5.1 5.4 7.5 2.9

124.4 ll!.l 84.4 12.4

9. NSL-ML 10. RL-ML I!. ss’-pm

33.5 126.4 46.5

5.0 4.2 2.0

17.9

2.8

12. x,-pm

deviations

(SD.)

3.5*** 1.9

for

variables

!- i2 studied

in the

83.4 80.2

-2,j**

-2,4**

-6, I*** -4.3***

1.4 -4.2*

81.1 174.3

-2.5** 1.7

-3.9*** 5.9***

4.9 7.8 7.2 2.9

-2.8 I .4 6.8* -2.3*

122. I 111.1 94.7 7.6

-0.5 1.4 -3.5 2.5**

2.3 0 -10,3*** 4.g***

37.0 131.7 45.0

5.7 6.4 4.2

-3.5 -5.3* 1.5

31.6 125.8 49.3

1.9 0.6

15.1

3.8

2.8”

16.4

SP = Children with clefts in the soft palate. HSP = Children with clefts in the hard and soft palate. For comparison, mean values for lo-year-old healthy children *p < 0.05. **p < 0.01. ***p < 0.001.

(nonclefts)

-2,g*** 1.5*

from

Thilander

5.4*** 5.9*** -4,3** -1.3

are given.‘$

was shorter in the cleft group than in children without clefts and ArL was shorter in Group HSP than in Group SP. The frequency of cross-bite occlusion was very low in the present investigation. The combined frequency of buccal and anterior cross-bite in the deciduous dentition did not exceed 10 percent, which is about the same as that reported in healthy children by Kutin and Hawes’” (8 percent buccal cross-bite) but lower than that found by Helm” (16 percent). The frequency of buccal cross-bite had increased in the mixed dentition and the total frequency was 11 to 21 percent compared to the frequency of posterior cross-bite of 7.2 percent in healthy children 7 to 9 years of age reported by Kutin and Hawes.‘” In a study by Swanson, MacCollum, and Richardson’” a low frequency of cross-bite (18 percent) was also reported in children with CPO. The palatal closure resembled a von Langenbeck procedure, but with relaxing incisions from outside the alveolar process in the mandible and continuing inside the alveolar process in the maxilla.16 Comparison of the results in this study with the analyses in other studies is difficult. The materials may vary to a considerable extent with respect to size of the clefts, growth pattern, surgical procedures used, and evaluation of the different variables. However, with these reservations in mind, it appears that children in whom the palatal surgery was performed as a push-back procedure have a higher frequency of cross-bite than do the children in the present study (Table VI). In the present study the influence of the size of the cleft on the occlusion, as previously found by Hellquist, Ponten, and Skoog,g could not be demonstrated. This may indicate that the type of surgery used on our patients did not interfere with the occlusion to such a degree that differences could be found between Groups SP and HSP.

Volume 76 Number 3

Postoperative

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Table Vi. Frequencies of no cross-bite after different types of surgical procedure clefts in the secondary palate Type of surgery

Present investigation* Cronin-Brauer push-backt

Veau-Wardill-Kilner W/V-Y (Demjen)

push-back? push-backs

No. of cases

4

4-6 l-9 10-11 2.5-4.9 5.0-6.9 7.0-9.0 5 7.4

21 21 21 104 71 40 99 16

253

in cases with

Cases without cross-bite (percent) 90 90 86 44 52 25 58 44

For comparison, data from other studies are included. *Longitudinal subsample. tSee Ranta, Oikari, and Haataja’” (cross-sectional $See Hellquist, Ponttn and Skoog.g §See Bishara, Schweiger, and La Velle.G

study).

As in other studies on CPO children, rg, 22the impairment of the occlusion during the transition from the deciduous to the permanent dentition was also found in the present investigation. The end result of the changes in the occlusion, however, cannot be evaluated until the time of cessation of facial growth. The results of the roentgenocephalometric study show differences of the same magnitude as reported in previous studies between CPO children and healthy children the same age. 2-4 The differences between Group SP and Group HSP also indicate that the craniofacial complex was influenced by the size of the cleft. However, it was not possible to determine whether these differences were caused by the palatal surgery or whether they depended on a characteristic morphology of the CPO children. Girls operated upon by the two most widely used palatoplasties (Veau-Wardill-Kilner procedure and von Langenbeck procedure) do not differ in their craniofacial morphology up to the age of 17.3 When the results from the cephalometric investigation and the analysis of the occlusion are compared with other studies, it appears that the occlusion and arch dimensions were more influenced by the type of surgery than was the craniofacial morphology. This is in agreement with Dahl,* who found, in comparing operated and nonoperated patients, that the influence of the surgery in CPO children was mainly localized to the dentoalveolar regions. The main goals in cleft palate repair are good maxillary growth and, above all, normal speech. There are differing opinions as to whether the von Langenbeck palatoplasty or the Veau-Wardill-Kilner push-back procedure gives the best results with regard to speech.r3, l5 The speech therapeutist at our clinic has found that 78 percent of the children in the present investigation had good or acceptable speech. Summary

and conclusions

A mixed longitudinal study of the occlusion and arch dimensions from 4 to 11 years of age was made on fifty-five children with solitary palatal clefts. A cephalometric study was also made on thirty of these patients when they were approximately 10 years of age. The

Am. 1. Orthod September 1979

palatal closure was made by means of a modified von Langenbeck procedure at a mean age of 1 year 9 months. The frequency of cross-bite in the deciduous dentition was comparable with that in children without clefts. As in other studies, an impairment of the occlusion was seen with increasing age. The children showed retrognathic faces and the difference between the cleft children and the noncleft children was of the same magnitude as in other studies. It was found that the arch dimensions and the craniofacial morphology were influenced by the size of the cleft, while the occlusion was not. The craniofacial morphology in the present investigation was comparable to that in other studies where a push-back technique had been used, but the frequency of cross-bite was lower. Thus, it would appear that the type of surgery influences the occlusion more than it affects the craniofacial morphology. REFERENCES 1. Bernstein, L.: The effect of timing of cleft pa!ate operations on subsequent growth of the maxilla, Laryngoscope 78: 1510-1565, 1968. 2. Bishara, S. E.: Effects of the Wardill-Kilner (V/W-Y) palatoplasty on facial growth, Angle Orthod. 45: 55-64, 1975. 3. Bishara, S. E., Enemark, H., and Tharp, R. F.: Chephalometric comparisons of the results of the Wardill-Kilner and von Langenbeck palatoplasties, Cleft Palate J. 13: 3 19-329, 1976. 4. Bishara, S. E., and Tharp, R. M.: Effects of von Langenbeck palatoplasty on facial growth, Angle Orthod. 47: 34-41, 1977. 5. Bishara, S. E.: Facial morphology and the Demjen W/V-Y technique: Cleft palate only. In Morris, H.L. (editor): The Bratislava Project: some results of cleft palate surgery, Iowa City, 1978, University of Iowa Press, pp. 108127. 6. Bishara, S. E., Schweiger, J. W., and La Velle, W. E.: Dental and oral aspects of the Demjen W/V-Y technique. In Morris, H. L. (editor): The Bratislava Project; some results of cleft palate surgery, Iowa City. 1978, University of Iowa Press, pp. 139- 158. 7. Bjork, A.: Kaebernes relation til det evrige kranium. In Lundstrom, A. (editor): Nordisk hirobok i ortodonti, 4 uppl., Stockholm, 1975, Sveriges Tandlakarforbunds Forlagsfdrening, pp. 70-75. 8. Dahl, E.: Craniofacial morphology in congenital clefts of the lip and palate: An x-ray cephalometric study of young adult males, Acta Odontol. Stand. 28: Supp. 57, 1970. 9. Hellquist. R., Ponttn, B., and Skoog, T.: The influence of cleft length and palatoplasty on the dental arch and deciduous occlusion in cases of clefts of the secondary palate, Stand. J. Plast. Reconstr. Surg. 12: 45-54, 1978. 10. Holm, A.-K.: Oral helath in 5-year-old Swedish children, Community Dent. Oral Epidemiol. 3: 184-189, 1975. 11. Huddart, A. G., and Bodenham, R. S.: The evaluation of arch form and occlusion in unilateral cleft palate subjects, Cleft Palate J. 9: 194-209, 1972. 12. Koberg, W.: System der Rehabilation von Patienten mit Lippen-Kiefer-Gaumenspalten, Opladen, 1971, Westduetcher Verlag. 13. Krause, C. J., Van Demark, D., and Tharp, R.: Palatoplasty: A comparative study, Trans. Am. Acad. Ophthalmol. Otolaryngol. 80: 551-559, 1975. 14. Kutin, G., and Hawes, R. R.: Posterior cross-bites in the deciduous and mixed dentitions, AM. J. ORTHOD. 56: 491-504, 1969. 15. Lindsay, W. K.: Von Langenbeck palatorrhaphy. In Grabb, W.C., Rosenstein, S., and Bzoch, K. (editors): Cleft lip and palate, Boston, 1971, Little, Brown & Company, pp. 399-402. 16. MacCollum, D. W., Richardson, S. O., and Swanson, L. T.: Habilitation of the cleft palate patient. h’. Engl. J. Med. 254: 299-307, 1956. 17. Moorrees, C. F. A.: The dentition of the growing child: A longitudinal study of dental development between 3 and 18 years of age, Cambridge, Mass., 1959, Harvard University Press, pp. 199-210. 18. Pruzansky, S., and Aduss, H.: Arch form and the deciduous occlusion in complete unilateral clefts, Cleft Palate J. 4: 41 l-418, 1964.

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19. Ranta, R., Oikari, T., and Haataja, J.: Prevalence of crossbite in deciduous and mixed dentition in Finnish children with operated cleft palate, Proc. Finn. Dent. Sot. 70: 20-24, 1974. 20. Ross, R. B., and Coupe, T. B.: Craniofacial morphology in six pairs of monozygotic twins discordant for cleft lip and palate, J. Canad. Dent. Assoc. 31: 149-157, 1965. 21. Ross, R. B., and Johnston, M. C.: Cleft lip and palate. Baltimore, 1972, Williams & Wilkins Company. 22. Shibasaki, Y., and Ross, R. B.: Facial growth in children with isolated cleft palate, Cleft Palate J. 6: 290-302, 1969. 23. Siegel, S.: Nonparametric statistics for behavioral sciences, International Student Edition, Tokyo, 1956, McGraw-Hill Book Company, Inc. 24. Swanson, L. T., MacCollum, D. W., and Richardson, S. 0.: Evaluation of the dental problems in the cleft palate patient, AM, J. ORTHOD. 42: 749-765, 1956. 25. Thilander, B.: The relation of dentofacial structures of the cranium in neutral occlusion of various ages: A seminar, Gothenburg, 1974 (unpublished data). s-901

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