EARLY A N D LATE B O N E G R A F T I N G IN C A S E S OF CLEFT LIP A N D P A L A T E

By D^vm NIATTHEWS, O.B.E., M.Chir., F.R.C.S., IVOR BROOMHEAD, M.Chir., F.R.C.S., WILLIAM GROSSMANN, M.D., D.Orth. R.C.S. and HENRY GOLDIN, F.R.C.S.

The Hospital for Sick Children, Great Ormond Street, London

Tins paper reports a survey of results covering a seven-year period between 1962 and 1968.

All cases were operated upon under the National Health Service. None operated upon in private clinics or elsewhere is included, so that as far as possible only those with uniformity of documentatioff from first consultation are reviewed. By restriction in this way it is hoped that comparisons and conclusions are valid and accurate. All the early cases reported were grafted at the Hospital for Sick Children, and the late cases at the Hospital for Sick Children and University College Hospital.

EARLY GRAFTS

Operative Technique.--All children are operated upon at about 3 months of age unless there is any constitutional reason for delay. The bone graft is taken from the left seventh rib with the child lying on its side and the scapula pulled forward by raising the left arm. In bilateral cases, which are operated on in two stages at an interval of three weeks, sufficient bone is taken for both sides, and half is buried subcutaneously in the chest wound for subsequent use. The taking of this graft adds 15 minutes to the length of the operation, and in no case has given rise to any anxiety. I f primary bone grafting is ultimately abandoned it will be because the long-term results do not justify it ; not because of technical hazard. The rib graft spans the alveolar gap and does not extend backwards on to the hard palate. It is enclosed in a Stellmach flap. The rib is cut in half longitudinally and inserted in two pieces side by side to allow maximum rapidity of vascularisation. Both ends of each piece of rib are notched with bone- nibbling forceps, so that the concave ends thus created can sit firmly astride the bony margins of the cleft. Great care is taken to place the grafts well down in the alveolar gap and wedge them tight so that they cannot slip upwards into the pyriform nasal fossa. The four chips obtained with the bone nibblers are inserted above the lateral ends of the grafts as support for the sunken alar base (Fig. I). It is both difficult and unwise, except in very exceptional circumstances, to raise two Stellmach flaps from the septum at the same operation, and only then if the operator is very experienced with this tech- nique ; it is much better to deal with the second side at a separate operation three weeks after the first.

Clinical Material.--The total number of early bone grafts in which survey was attempted was 94; of these, 75 were unilateral and 19 bilateral (Table I). The only complication of the operation was exposure of the bone graft in two cases ; both healed without loss of graft so far as is known. Two cases died later in childhood of unrelated congenital malformations. The 94 cases had 114 grafts ; of these 73 cases (77"7 per cent.) have been examined in the period November 1968 to January 1969 and represent 88 grafts (Table n). Those with the longest period since grafting (I962) are above the average percentage of the follow-up and so this survey is a fair review of the whole period. Of the 21 cases not seen in the three-month review period, II were seen in the regular out-patient follow-up clinic during 1968, some only a short while before the

115

I16 BRITISH JOURNAL OF PLASTIC SURGERY

review period. Thus a total of 84 cases (89 per cent.) have been seen within the last year out of 94 cases operated upon.

Classification of Results.--Straightforward adoption of the standard classification of Class I, Class II and Class I I I occlusion is not valid for cleft cases since the classification presupposes the maxilla to be in one piece ; besides not giving sufficient information to be useful, it would be impossible to apply with a fragmented maxilla. A new classifica- tion has therefore been adopted to meet these special needs (Table III).

FIG. I Early Bone Grafting.-- Insertion of notched split rib grafts into alveolar gap in front of Stellmach flap. Small spare

pieces of bone inserted below the alar base.

Class A means that all segments of the maxilla are in normal occlusion with the mandible.

Class B has needed to be subdiviaed because of different kinds of imperfection. B (i) is well-nigh perfect, the only defect being that the tooth bordering the x:left on the lesser segment is in lingual occlusion and will need minor conventional orthodontics to cor- rect it. B (ii) has normal occlusion of the greater segment but lingual occlusion, which may only be very slight, of the lesser segment. This observation has been most accurately recorded and the result stringently applied to classification ; all so found have been classified in B (ii) instead of A. B (iii) is a group in which the arch itself is perfect but is too small. Sometimes one can observe with the passage of time the drift of a Class A result into a Class B (iii) result. The arch has been maintained and the bone graft has persisted on X-ray evidence ; maxillary collapse has not occurred and yet the result is dentally, and sometimes cosmetically, unsatisfactory. Some of these cases are well

EARLY AND LATE BONE GRAFTING

TABLE I

Early Bone Grafts

Bone grafts performed at age of 3 months over the period January 1962 to January 1968 Total number operated upon 94

Unilateral 75 Bilateral 19

Mortality . . . 2 (unrelated) cerebral I

cardiac I Complications of surgery--

Exposed bone graft 2 (both 1964)

TABLE I I

Early Bone Grafts

Cases examined in follow-up, November 1968 to January 1969

Year Operations Followed-up

1962 1963 1964 1965 1966 1967-8

io I i 24 12 18 19

9 (90%) 8 (72%)

16 (67%) 9 (75%)

13 (72%) 18 (95%)

-i 94 (= II4 grafts) 73 (77"7%) = 88 grafts

TABLE I I I

Early Bone Grafts

A Perfect result--Class I occlusion. B (i) Class I occlusion except for c tooth on lesser segment.

(ii) Class I occlusion greater segment. Lingual occlusion lesser segment.

(iii) Good arch in Class I I I occlusion. C Failures--Class III occlusion with some part of arch collapsed.

TABLE I V

Early Bone Grafts

Analysis of results of 73 cases reviewed November 1968 to January 1969

117

Year Number A B (i) B (ii) B (iii) C

1962 1963 1964 1965 1966 1967-8

9 8

16 9

13 18

o I (I3%) I (6%) 1 (11%) 2 (15%) 6 (32%)

I (11%) o 9 (56%) 2 (22%) 4 (31%) 5 (26%)

2 (22%) 1 (I3%) 2 (13%) 3 (34%) I (8%) I (6%)

5 (56%) 3 (37%) 3 (I9%) I (11%) 6 (46%) 3 (18%)

73 1I (I6%) 21 (28%) IO (I4%) 21 (28%)

58%

1 (11%) 3 (37%) z (6%) 2 (22%) o 3 (18%)

I0 (14%)

118 BRITISH JOURNAL OF PLASTIC SURGERY

suited to a combination of rapid expansion, secondary bone grafting and maxillary o s t e o t o m y .

Class C are failures. T h e y s h o w n an overall Class I I I occlus ion of all segments of the maxil la , and in add i t ion a collapse of s o m e part o f the smal l maxi l lary arch. T h i s too <:an be seen despite X-ray evidence of survival of the bone graft, or grafts.

TABLE V

Early Bone Grafts With the addition of II cases seen in the last year but before

November 1968 to January 1969

(I I +73 = 84 out of total of 94 operations performed)

Total operations: 94 Number seen: 84 (89%)

A B (i) B (ii) B (iii) C I I ( 1 3 % ) 27 (32%) 13 ( 1 5 % ) 21 ( 2 5 % ) 12 (14%)

I. -60%. t

TABLE V I

Early Bone Grafts Survival of bone graft in 70 cases X-rayed

Year

I962 1963 1964 I965 1966 1967-8

X-rayed Surviving Not surviving

9 8

2 I IO

9 13

8 7

19 8 9

1I

I

I

2 2

2

7o 62 (88%) 8 (12%)

TABLE VII

Early Bone Grafts X-ray evidence of teeth growing in bone gra~ (out of 7 ° cases)

1962 2 1963 4 1964 7 1965 4 1966 2 1967 3

22 (31"5%)

Analysis of the 73 cases examined in the three-month review period (November I968 to January 1969), year by year, shows an overall reasonably good result (that is to say A, B (i) and B (ii) in 58 per cent. (Table IV), but it is to be noted that in the A group, the perfect results, the majority tend to be those operated on more recently. But this is not seen in the near perfect (B (i) and B (ii))nor is it seen in those with the good small arch (B (iii)), where those operated on longest show high figures. With the failures

EARLY AND LATE BONE G R A F T I N G I I 9

(C) the spread is also fairly even over the years. I f the I i cases seen in the last year but not in the last three months are included, the figures are substantially the same (Table V). These results suggest that except perhaps in Group A the quality of the result is not influenced by the length of time which has elapsed since the cases were classified. There is no general slide from A to B (i), (ii), and (iii) to C with the passage of time.

X-ray Studies.hOf 70 cases X-rayed 62 (88 per cent.) showed survival of the bone graft (Table VI) ; eight out of nine grafts which had been in place for the full seven years of the survey were radiologically intact. There is no doubt therefore of the long- term survival of early grafts.

In 22 cases, representing 31.5 per cent. of those examined, there was radiological evidence of teeth growing in and through the bone graft (Table VII): In one case two

FIG. 2

Early Bone Grafting.- T w o tee th e rup t ing in the space filled wi th a rib graf t at the age o f 3 m o n t h s .

teeth were firmly established in the graft and had erupted in slight lingual occlusion suitable for conventional orthodontic treatment (Fig. 2).

Pre-operative Orthodontics.--An attempt was made to assess the value of this technique in contributing to the end-result. Its use has been restricted to three specific circumstances. Firstly to set back the moderately protruded premaxilla and expand the lateral segments in bilateral complete clefts (Fig. 3). The minor degrees of protrusion do not require orthodontics. The major degrees cannot be corrected without unaccep- table buckling of the septum (Fig. 4). Secondly, to expand the lesser segment and rotate the anterior end of the greater segment in complete unilateral clefts (Fig. 5). I f this is completely achieved it materially assists the chances of the maintenance of an uncol- lapsed arch by a bone graft. Thirdly, to correct the alveolar obliquity in a cleft limited to lip and alveolus (Fig. 6).

Pre-operative orthodontics is of great value in all three of these conditions. But it is not of course a passport to certain surgical success, and one can have failures even after orthodontics has produced good initial movement. But the better the arch pre- operatively the better are the surgeon's chances of maintaining it and the easier is the operation to do. For successful pre-operative orthodontics the orthodontist must be

FIG. 3 Pre-operative Orthodontics. -- Moderately protruded premaxilla in a case of bilateral complete cleft of lip and palate set back by pre-

operative orthodontics.

FIG. 4 Pre-operative Orthodontics.--To show the buckling of the septum which results from the excessive pressure required in attempting to set back the

grossly protruded premaxilla.

FIG. 5 FIG. 6

Fig. 5.--Pre-operative Orthodontics.--Alignment of maxillary fragments in complete unilateral cleft.

Fig. 6.--Pre-operative Orthodontics. -- Alignment of alveolus in cleft restricted to lip and " primary " palate,

EARLY AND LATE BONE GRAFTING I 2 I

given the chance to start treatment within the first two or three weeks of life. After this his task is much more difficult. An analysis of 42 cases (Table VIII) in which pre- operative orthodontics was used shows that the results in those in which initial move- ment was good were better than those in which it was poor. Some initial movement occurred in all, however, and the dividing-line between good and poor initial movement must necessarily be a subjective conclusion from the study of models, and this is far from

TABLE V I I I

Early Bone Grafts

Analysis of end-results to date of 42 cases which have had pre-operative orthodontics

Year _AA

J _ _ 1962 - -

]1963 1964 i 1965 1966 1967-8

B (i)

I3

Good initial movement (32 cases

B ( i i ) B__(iii) i

- 1

- - 2

3 - - 3 I

6 3

I Poor initial movement f (IO cases) i

B (ii) C A B (i)

- - I

1 2

2 2 4 I

r

~ 8 4 . 5 % - - - - - 70%

TABLE IX

Early Bone Grafts

Analysis of quality of results in bilateral cases examined November I968 to January I969

B (iii) ! C

i - -

I - -

r l

I

i ! 2 ,

Premaxillary set-back

Year With Without

1962 1963 1964 1965 1966 1967-8

A B (i) C, C

X-

w

B (i) A, B (i), B (i), B (i), C

A, A, B (i), C

5 xo

easy. There must necessarily be borderline cases which could affect the percentages considerably in a small series.

Reposition of the Premaxilla.--An attempt has also been made to investigate the quality of results in bilateral cases in relation to the vexed question of whether or not to set the premaxilla back. This has only been done in the most severe cases (Table IX). Of 15 bilateral cases examined, one-third of them have been set back, and from these it would seem that, provided the operation is done with meticulous attention to details first set out by Denis Browne (I949), the results after a" set-back" operation are about the same as without it. The surgeon can be reassured that in the very severe cases when there is virtually no alternative the end-result is not prejudiced by this radical

122 BRITISH JOURNAL OF PLASTIC SURGERY

operation. This observation is only pertinent, however, when these set-backs have been accompanied by bilateral bone grafts. The grafts have been seen to persist radiologi- cally. It is doubtful whether a " set-back" operation without bone grafts would pro- duce a similar result. I f this is true, it follows that if a set-back is done a bone graft is obligatory.

TABLE X

Early Bone Grafts

Analysis of 84 cases without bone grafting chosen at random

A 7 (8"3%) B (i) r4 (I6"6%) B (ii) 25 (29"8%) B (iii) r 5 (r7"9%) C 23 (27"4%)

I 54"7% !

With bone grafting (for comparison)

A H ( I 3 % ) B(i) 27(3~%) B(ii) I 3 ( I 5 % ) B(iii) 2x(25%) C I2 ( I4%)

i 60% I

Conc lus ions .n i t is unwise to be comprehensive in a hurry, but this survey has established a number of points. It has shown that early bone grafting in young infants does not increase the operative risk. It has also shown that, in the period covered, bone in the position and form of the graft survives radiologically in 88 per cent. of cases, and that in 31"5 per cent. teeth move into the area of the graft and erupt. It has also shown that 47 per cent. of cases required only minor conventional orthodontics to establish perfect occlusion, and 13 per cent. had perfect resuks. It has also shown 14 per cent. of cases to fail with maxillary collapse despite the radiological evidence of bone in the grafted area, and 25 per cent. of cases to result in a small arch with need for further surgery in adolescence.

Pre-operative orthodontics is seen to contribute both to the quality of the result and to facilitation of operation in the types of case for which it has been used, and the setting back of the severely protruded premaxilla has been shown not to affect the quality of the end result, provided bilateral bone grafts are inserted.

The limitation of the survey is that it covers a period of only seven years with the oldest children approaching 9 years of age. It is intended to review the same cases again five years hence.

During the period covered all cases with alveolar clefts were treated by bone grafting and there is, therefore, no simultaneous series without bone grafts for comparison. But study of the case records of 84 cases of the same age-range operated upon in the seven years before the start of bone grafting show interesting differences (Table X). Groups A and B (i) (the perfect results and those with only one tooth in lingual occlu- sion) account for 45 per cent. with bone grafting and 25 per cent. without. Group B (ii) (those with lingual occlusion of one segment) account for only 15 per cent. with bone grafting and 29"8 per cent without. B (iii) (a good but small arch) was achieved in 25 per cent. with bone grafting and 17. 9 per cent. without. C (poor arch and segmental collapse) represent 14 per cent. after bone grafting and 27. 4 per cent. without. 1

LATE GRAFTS

The technique of rapid expansion followed by the insertion of a bone graft was first reported by two of us (D. M. and W. G.) at the International Congress in Washington in

1 The authors wish to emphasise that they do not put these results forward as a controUed trial. They are included because they are the only records available to them of cases of exactly comparable age in which treatment differed by the omission of a bone graft.

EARLY AND LATE BONE GRAFTING I23

I963 on a series of 18 cases. This review is of 55 cases operated on between January I962 and January I968 (Table XI).

Technique.--Sectional cap splints are applied to the parts of the maxilla and con- nected by a Fischer expansion screw set in acrylic. In unilateral clefts a single screw

TABLE X I

Late Bone Grafts

Rapid expansion and bone grafting

Total number treated~ 1962 to 1967 55 Total number examined~ November 1968 to January 1969 42 (80%) Not seen, November 1968 to January 1969 13 Of these 13, 5 have been seen in the last year. The notes, X-rays

and study modds of the remaining 8 have been examined

is set transversely to expand the two fragments. In bilateral cases a second screw is set at right angles to the first to move the premaxilla (Fig. 7). The secret of orthodontic success is the rapidity of the expansion. I f this is completed in two or three weeks the amount of force exerted moves whole segments without demonstrable angulation of the teeth. The patient or parents are instructed to turn the expansion screw with the key three times a day. The segments are deliberately slightly overexpanded in younger patients in whom growth is not complete. Pre-existing fistula: are not macroscopically enlarged by this procedure.

When expansion of the maxillary fragments is complete a thin graft of iliac bone is inserted between the nasal and buccal mucous layers after pre-existing fistula: have been closed. The graft must be set well down and wedged in the alveolar gap ; it is useless to put it in the pyriform nasal fossa. The approach is through the buccal snlcus. The extension apparatus is maintained for seven weeks while the graft is consolidating. Afterwards a removable appliance is used day and night for three months. Thereafter a denture is worn by day to take teeth to fill the gap or a fixed bridge is applied as the patient wishes.

The graft extends back for the full length of the hard palate, and a forward exten- sion can also be fashioned where necessary to support a sunken alar base. The periosteal surface of this graft, which is the more resistant to infection, is usually set against the nasal mucosa when a difficult fistula has had to be closed. In the absence of a fistula it does not matter whether the periosteal surface faces the buccal or nasal mucosa. The graft is wedged on its upper surface with a matchstick of bone on its medial and lateral borders to ensure that it does not ride up out of the alveolar gap. When an anterior shelf is used, chip grafts are built up on it as support for the ala.

Modifications.--In unilateral cases, if the lesser segment is angled upwards anteriorly in the open bite position, the operation is combined with a lateral osteotomy of this segment. In these cases the expansion apparatus is removed on the morning of opera- tion and replaced by segmental cap splints with fixtures on which to screw precast locking bars. These splints and bars are made by cutting a dental study model of the maxilla and placing the segments in their correct position on a study model of the mandible (Fig. 8, A and B). In bilateral cases similar precast segmental cap splints and locking bars are fixed on the morning of operation if it is desired to adjust the vertical height of the premaxilla at operation (Fig. 9).

In cases in which rapid expansion and bone grafting have enlarged the maxillary arch to match the mandibular arch, but where normal occlusion is still prevented by retro-position of the maxilla, maxillary osteotomy to bring the maxilla forward can be

I 2 4 B R I T I S H J O U R N A L OF P L A S T I C SURGERY

done without risk of disturbing the bone graft. An interval of six months should be allowed to elapse after insertion of the graft. The maxillary osteotomy is not difficult to perform. The essential features are to section the septal bone and cartilage through submucous incisions close to the nostril floor ; to divide the pterygoid plates with an

Fxo. 7 Late Bone Grafting.--One expans ion screw get t ransverse ly to expand t he lateral s egment s and a second set at r igh t angles to it

to m o v e the premaxil la .

osteotome ; and to cut the lateral maxillary walls at the level of the antral floor with a dental drill. It is not necessary to elevate or cut the palatal mucosa behind the anterior teeth (Fig. Io, A to E). None of the cases of early bone grafting which have resulted in a B (iii) result is yet old enough for osteotomy, but this would seem to be the logical procedure to adopt at the right age.

The Purposes of the Operation.--These may be summarised as :

I. To correct the maxillary malocclusion in a collapsed maxilla, and permit the eruption of teeth in the gap so created.

2. To relieve an obstructed nasal airway, or airways.

A

B

FIG. 8 Late Bone Grafting.-- Apparatus used to combine bone grafting with lateral osteotomy. A, On segmental model ; B, in situ on

completion of operation.

FIG. 9 Late Bone Orafting.--Apparatus used to align premaxilla and

lateral semalents.

I26 BRITISH JOURNAL OF PLASTIC SURGERY

3. To improve the patient's appearance by expanding the middle third of the face, elevating the alar base, and stretching a tight upper lip.

Optimum Age for Operation.--Rapid expansion can be undertaken as soon as suffi- cient permanent teeth have erupted to secure fixation of the apparatus. It can thus be undertaken with a mixed dentition, and at first our cases were operated upon at IO to 12

FIG. io Late Bone Grafting.--Combination of expansion with maxiUary osteotomy. A, Position before expansion. B, after expansion. C, Position after maxillary osteotomy. D, Fixation apparatus used at osteotomy.

E, Profiles to show clinical improvement.

years of age. It is our preference now, however, to wait until about 18, with the inten- tion of setting the maxilla in occlusion with the fully developed mandible, so that the relationship will remain correct throughout adult life. Nasal obstruction however, causing sinus infection, middle ear deafness or repeated upper respiratory tract infec- tions, is an overriding priority and operation is then undertaken as soon as the orthodontic treatment can be satisfactorily carried out.

Analysis of Survey.raThe total number of cases operated upon between January 1962 and January 1968 is 55 (Table XII). Of these, 42 (8o per cent.) have been examined in the period November I968 to January 1969 and another five within the last year, making a total of 84 per cent. The documents of the remaining eight cases have also been studied in detail.

These studies reveal an average age of grafting at 14 years 5 months. The youngest

EARLY AND LATE BONE GRAFTING :27

was 8 and the oldest 18. There were 36 unilateral cases and 19 bilateral. Twenty-one (38 per cent.) had pre-existing fistulm which were closed at operation. Satisfactory orthodontic expansion was obtained in all cases. Operations were accompanied by lateral osteotomies in four cases and the height of the premaxiUa was adjusted in two. So far none of the failed cases of early bone grafting has reached the age when secondary bone grafting can be attempted, but there is no reason to suppose that previous operation will make rapid expansion more difficult to achieve. Ziegelmayer (I956), and others

FIG. IO~ E

working on cadaver material, have demonstrated that even the normal uncleft maxilla can be separated along its primary suture lines by rapid expansion.

Of the 55 cases studied, 35 (74 per cent.) have remained in perfect occlusion and seven (I 5 per cent.) have shown very minor degrees of lingual occlusion. It is possible that these have resulted from a slight outward angulation of the alveolus and teeth during expansion which has subsequently settled back, but this is difficult to prove. In five cases (Io'5 per cent.) there has been relapse and these must be accounted as failures (Table I3).

Thirty-five cases have been re-X-rayed during follow-up and of these 32 (91"5 per cent.) have shown the persistence of the bone graft (Table I4). In several, teeth have erupted into the gap created by the expansion. Sometimes these teeth need conventional orthodontics to turn them or to align them.

Complications.--In no case has the graft been lost, but in I i (2o per cent.) there has been post-operative exposure of the graft at the site of the repaired fistula. The most stringent observation has been made in this respect, and even the most minute exposure

I28 BRITISH JOURNAL OF PLASTIC SURGERY

TABLE X I I

Late Bone Grafts

Analysis of the total series of 55 cases

Average age at grafting, x4 years 5 months Youngest 8 Oldest I8

Unilateral cases : 36. Bilateral cases : I9 Fisrulee needing to be closed at t ime of grafting 2I (38%) Satisfactory initial expansion. 55 (lOO%) Lateral osteotomies . . . 4 Adjustment of premaxillary elevation 2

TABLE X I I I

Late Bone Grafts

Analysis of results--rapid expansion and bone grafting 55 cases. 47 cases examined. 8 lost to follow-up

Years since Good Fair grafting result result* Failures

6½ 6 5½ 5 4½ 4 3~ 3 2½ 2

i½

35 (74%)

° ° .

I

I

2

. H

2

. . °

. . .

I

7 ( I5%)

i" (u~i.)

2' "(bils) I (uni.)

I" "(bil.)

. . .

5 (Io'5%)

* Cases of minor lingual occlusion of one or more segments.

TABLE XI V

Late Bone Grafts

Number of cases X-rayed, November I968 to January I969 Number showing presence of bone graft . Number showing no surviving bone graft

35 32 (9v5%)

3 (8.5%)

TABLE X V

Late Bone Grafts

Complications

Post-operative exposure of graft Surgery needed to cover graft . Chip sequestra ext ruded.

II (20%) 4 (7%)

i i (20%)

EARLY AND LATE BONE GRAFTING I2 9

has been recorded ; seven of these I I cases healed without the need for interference. In the remaining four the suture line was either restitched or a rotation flap was swung to cover the bone, in all cases with success. Excessive zeal in building up the ala has resulted in the extrusion of one or more chip sequestra through the suture line in I I cases (2o per cent.). Satisfactory healing followed these extrusions (Table XV).

Conclusions : This six and a half year survey has shown 74 per cent. of good results and a further 15 per cent. of results with only minor occlusal defects, making a total of 89 per cent. From the patients' point of view the most dramatic outcome of operation is the relief of nasal obstruction, which is experienced within a week or ten days of the commencement of rapid expansion and is permanent.

REFERENCES

BROWNE, DENIS (1949). Hare lip. Ann. R. Coll. Surg. 5, 1969. MATTHEW$, D. and GROSSMAN, W. (I964). Trans. int. Soc. plast. Surg., Thi rd Congr.~

1963, p. 239. Amsterdam : Excerpta Medica. STELLMACH, R. (1955). Fortschr. Kieferorthop., x6, 247. ZIEGELMAYER~ G. (1956). " Gaumennahterweiterungfl ' p. 121. Munich : Hanser.