Combined orthodontic and surgical management of maxillary protrusion in adults

rt mana William

L&n&b,

R.

roffit,

D.D.S.,

h.D.,*

and

Raymond

P. White,

D.D.S.,

Ph.

KY., ~a! Rich,mcmd, Vn.

ntcrior maxillary ostectonry, with retraction of the alveolar segment containing the anterior t,eeth, offers a rapid and efficient way to reduce maxillary incisor protrusion in adults.l-* The surgical procedure is not technically difficult, and this has contributed to its increasing popularity. However, it is rare for only the maxillary incisor teeth to be malposed when maxillary protrusion exists. For this reason, surgical intervention alone can lead to incomplete correction of occlusal problems. Patients with complex occlusal problems need orthodontic as well as surgical treatment. Unlike surgical intervention in the mandibular body or ramus, or more extensive maxillary surgical procedures which reposition the entire tooth-bearing segments of the jaws, the anterior maxilla.ry ostectomy involves little more than the alveolar process of the anterior maxilla. In many instances it is possible to achieve the same results from orthodontic treatment alone as are achieved by combined orthodontic and surgical procedures. It is difficult to be objective about whether a patient should be treated by orthodontic or surgical methods when a result can be achieved by either method. Surgeons tend to believe that if it can be done surgically, it should be; orthodontists instinctively take the opposing view, feeling that where tooth repositioning can be achieved orthodontically, this is the procedure of choice. This article discusses -the benefits and the risks to the patient of orthodontic and surgical procedures and the potential interaction of orthodontists and oral surgeons in the treatment of maxillary protrusion. We hope that this discussion will contribute to rational treatment planning using the best of both approaches. From the Department of Orthodontics, and the Department of Oral Surgery, University. *Present 32610.

368

address:

College

of

Dentistry,

University School of University

of Kentucky College of Dentistry, Dentistry, Virginia Commonwealth of

Florida,

Gainesville,

Fla.

Volume Nwm

64

MaxillarzJ protrusion

b e?- 4

Table

I. Effect of alveolar

ostectomy

No. Total Within segment Distal to segment Adjacent to ostectomv

Number

of

Number

of teeth

*D&a Relative

from

ostectomies:

advantages

teeth

Per

28. 22 6 17

cent 14.8 15.6 12.5 34.0

25.

requiring

Department

of

of

nonresponsive teeth

189 141 48 50

site

369

on tooth vitality* No.

-

in adults

endodontic of Oral

and

Surgery,

disadvantages

therapy:

5.

University of

surgical

of Kentucky versus

College

of Dentistry.

orthodontic

treatment

The possible risks of surgical repositioning of an anterior maxillary segment fall into three major categories: (1) surgical catastrophes, such as anesthetic accidents or failure to achieve healing after the ostectomy; (2) devitalization of teeth and bone in the involved alveolar segment ; and (3) loss of alveolar bone at the ostectomy site, with consequent future periodontal involvement in these areas. All these risks are real. All can be evaluated accurately on the basis of experience to the present and ca,n be shown to be quite small. Rapid advancements in oral and facial surgery occurred after World War II in European treatment centers, where most of the newer alveolar surgical procedures were pioneered. Elective surgery in these centers was stimulated by experience gained in treating traumatic injuries to the face, where it was observed that remarkable healing of maxillary injuries was achieved. LOSS of bony segments is rare in cases of traumatic injury. This fact is probably related to the excellent collateral blood supply to the facial area. The same excellent healing is observed after elective surgery. Anesthetic accidents are always a possibility (as they are when oral surgery is performed for any purpose), but these incidents are rare and are well managsed in the modern hospital setting. Thus, the risk of a surgical catastrophe is quite small. Upon first consideration, it seems inevitable that devitalization of teeth and bone in an alveolar segment would occur when the segment is moved surgically. Thle neurovascular bundle to the maxillary anterior teeth could be cut conceivably at four separate locations during a typical ostectomy. Ample clinical evidence demonstrates, however, that devitalization of the teeth and bone rarely ocours, even though denervation and loss of sensation to teeth and mucosa can be expected for a variable period of time after ostectomy. F’erfusion experiments have demonstrated the rich collateral blood supply to the alveolar bone and teeth.j If the ostectomy cut clears the apex of a tooth by a few millimeters, the pulp of the tooth remains vital even though the nerve has been cut. Regeneration of sensory nerve fibers takes place over a period of months, and within 6 months of the segmental ostectomy procedure, electrical or thermal pulp tests for sensation show a positive response. In some instances, regeneration of the nerves is apparently blocked, so that pulpal sensation does not return. When this occurs,

70

Profiit

tooth vitality

and Waite tan be demonstrated

by other means and endodontic

treatment

is

not, required.

Data from an evaluation of a series of patients at the University of Kentucky are shown in Table I. Approximately 80 per cent of teeth in or near an alveolar ostectomy segment give a positive response to vitality tests a few months after surgical intervention. Only a few of the teeth which did not respond to electrical pulp testing showed pulpal degeneration and required endodontic therapy. In these instances we observed an ostectomy cut passing through the root of the involved tooth. Subsequently, conventional endodontic therapy gave an aeceptable result. The health of the periodontium at an ostectomy site is influenced primarily by the care with which alveolar bone was preserved in areas adjacent to the bony cuts. St a premolar extraction site, good bony contours are obtained unless the ostectomy cut removes bone immediately adjacent to the long axis of a canine or second premolar root. When bone is removed too close to the root, a bony defect may remain after the operation. Where a cut is to be made between adjacent teeth (as between the maxillary central incisors when a midline split anteriorly is part of the surgical procedure), interseptal bone may be lost if a bur cut is brought between teeth all the way to the height of the alveolar crest of bone. If the last few millimeters of bone is split with an osteotome, excellent gingival contours are obtained. Postoperative periodontal problems occur only as a result of poor surgical technique. These incidents are rare. One problem which occurs in patients undergoing prolonged orthodontic retraction of incisors is root resorption. The factors leading to root resorption during orthodontic treatment remain unknown, but it is apparent that length of treatment is an important variable.” Root resorption is seen more frequently in persons whose orthodontic treatment takes longer than 18 to 2-1 months, a.nd it is minimal in patients treated for less than a year. Root resorption does not occur in patients managed surgically. It is probably fair to say that the risk of root resorption in routine, well-managed orthodontic retraction of maxillary incisors is approximately equal to the risk of devitalization of teeth or the creation of periodontal defects accompanying surgical retraction. Neither of these is a major problem. The major advantages of using a surgical procedure for retraction of maxillary incisors in a maxillary protrusion problem are three : 1. Decreased total treatment time. If no orthodontic treatment is required, the total treatment time can be very short. In a more typical situation, however, where full orthodontic appliances are to be used in conjunction with the ostectomy, the saving in treatment time over conventional orthodontics is about -10 per cent. Treatment time might be reduced from 18 months of active trea,tment with orthodontic methods alone to 10 months of active treatment including orthodontic and surgical procedures for a similar result. 2. Increased possibility of maximum retraction of the incisor segment.

Volume Number

64 4

Maxillary

protrusion

in adults

371

Orthodontic mechanics at present allow maximal retraction of incisor teeth, but if 100 per cent retraction of incisors is desired in closing an extraction site, and if no tipping of teeth is to be allowed, the anchorage requirements are severe. Great c.are in orthodontic treatment is required to prevent loss of posterior anchorage. Surgical retraction is always a maximum anchorage proceclure. As protrusion becomes less severe, but extraction of maxillary premolars is still indicated, this maximum retraction requirement becomes less of an advantage. If some mesial movement of molars into a solid Class II relationship is required, the inflexibility of an ostectomy in providing for individual tooth movement may become a positive disadvantage. In general, the more severe the protrusion, the more advantage there is in surgical rather than orthodontic retraction. 3. Intrusion of anterior teeth along with retraction of the maxillary segment. Once a, maxillary anterior segment has been surgica.lly released, it can be repositioned within limits, both vertically and horizontally. Intrusion of maxillary incisors during orthodontic treatment is possible but difficult. When the anterior segment is intruded surgically, the floor of the nose is elevated. Interference at the nasal septum becomes a limiting factor at approximately 4 mm .4 If intrusion is kept within this limit, remodeling of the nasal floor after surgical intervention restores the original contours within a few months. Such intrusion is a real advantage in many deep-bite protrusion situations. Although treatment time is decreased when an ostectomy is used to reduce protrusion, the total cost of treatment may not be reduced. Geographic differences may determine what factors will affect cost, but it is reasonable to assume that costs of combined treatment will be somewhat greater than the cost of orthodontic or surgical treatment alone. The length of time a patient is wearing appliances may be reduced by 40 per cent, but the length of chair time for that patient mrill be reduced less, because the time required fsor fabrication of the appliances remains constant. In addition to the surgeon’s fee, hospitalization for 18 to 72 hours is required, and these costs must also be considered. The availability of third party payment and the more rapid treatment progress if surgical means are employed have influenced patients to believe that combined treatment is worth the additional cost. Patients should understand all aspects of treatment, including cost, before treatment begins. A final difference between orthodontic or surgical treatment alone and the combined orthodontic-surgical procedure is the requirement for cooperation between specialists in the combined approach. This can be either an advantage or a disadvantage, depending upon the personalities and attitudes of the individuals involved. In any cooperative situation, some give and take is required. For both the surgeon and the orthodontist, the benefits to patients and the opportunity to learn can be important advantages of a cooperative relationsh.ip, outweighing any inconvenience caused by the requirement to consult.

Treatment

plcmning

for

anterior

maxiilary

ostectomy

in

conjunction

with

or&o

treatment

The diagnostic criteria for maxillary protrusion and the steps in gathering data for the diagnosis are independent of the treatment method. The objective of a diagnostic evaluation should be to establish the nature and location of the problem, differentiating between maxillary skeletal and alveolar protrusion and mandibular skeletal and alveolar retrusion. Evaluation of the patient and cephalometric analysis are necessary for this purpose. Any appropriate set of measurements may be used to make this diagnosis. In an evaluation of the patient, two factors deserve particular attention in the clinical examination. The relative ba.lance of the face, as influenced by nose and chin, is important in determining the over-a,11 profile effect. Orthodontic retraction of maxillary incisors can make an already large nose more obvious. Surgical retraction of the alveolar segment will accentuate the nose even more, because the retraction of anterior nasal spine in the surgical procedure tends to retract the upper part of the upper lip more than orthodontic retraction of incisors. Comparing the two approaches, the surgical retraction usually gives a less obtuse nasolabial angle (which is generally desirable esthetically) while accentuating the prominence of the nose (which is frequently undesirable) .71s The length of the upper lip also should be considered, since prominence of incisors vertically as well as horizontally may be an esthetic problem. If the ?Jpper lip is long, it may not be desirable to retract incisors as much as would otherwise be thought from an analysis of tooth relationships. If the upper lip is short, there may be an a,dditional indication for intrusion as well as retraction of incisors. Locating the underlying problem is of prime importance in the diagnostic procedure. It does not automatically follow that the focus of treatment should be on that problem. It may be better to make compensatory changes, using treatment to mask the problem rather than attempting to a,ttack it directly. A frequent example of this occurs in adults who have a combination of maxillary alveolar protrusion and mandibular skeletal retrusion. Rather than bringing the mandible forward surgically, it may be better to plan a maxillary alveolar ostectomy plus a procedure to augment the deficient chin. This approach is beneficial when a degree of mandibular dental compensation for the Class II relationship already exists, so that the chin would still be deficient, even if the teeth were placed into the most convenient occlusal relationship. Genioplasty under these circumstances may give a more stable correction.7 The possible effects of several different treatment plans can be predicted by manipulating casts and tracings to predict the results. Methods for predicting results in combined orthodontic and surgical procedures have been published recently.8 Cephalometric prediction is essential to ensure that esthetic results are anticipated correctly as well as to evaluate various treatment possibilities. At present, surgical retraction of an anterior segment is limited to adult patients for two reasons. First of all, there is no possibility of growth facilitating orthodontic treatment in an adult. Where there is a possibility that, growth can be influenced to obtain correction of a skeletal malocclusion, this should be

Maxillary

Fig.

1. Case

1. Preoperative

and

3 years

postoperative

prolrusion

sin adults

373

photographs.

attempted before surgical intervention or before prolonged tooth movement procedures arc undertaken. Second, there is a possibility that surgical intervention in an area will interfere with future growth in an unpredictable fashion. It is conceivable that as our knowledge of the subject increases, the age at which surgical proc.ed.ures can be recommended will be lowered. At present, it seems prudent to reserve surgical intervention for patients in whom growth is complete or essentially complete; that is, patients who are at least in their late teens. Interaction

of orthodontics

and

surgery

in treatment

sequence

There has been considerable controversy as to whether orthodontic tooth movement should be done before or after surgery. At present, interocclusal acrylic indices can be used to stabilize the teeth in any desired position following surgical intervention, whether or not the occlusion is prepared to give good interdigitation of teeth prior to surgery. Full-banded orthodontic appliances provide excellent immobilization at the time of surgery, even if fixation within a single arch rather than intermaxillary fixation is to be used. These two factors make it feasible to delay some occlusal correction by orthodontic methods until after the surgical procedure. As a general rule for combined-treatment cases, we believe that tooth movement in the transverse (posterior cross-bite) plane of space is best accomplished after surgical intervention. Vertical repositioning of teeth, as in the leveling of a mandibular arch to correct an excessive occlusal curve, can be scheduled before or after surgery, depending on the method of leveling employed. If leveling can be accomplished by extrusion of premolars, it can be deferred until after the operation. If intrusion of incisors is to be attempted, this must be done before surgery. Repositioning of teeth in the anteroposterior plane of space, either retracting incisors or orthodontically closing extraction spaces, is best done before surgery.

Am. J. O?aOd. October

Fig. 2. Case of lower

1. Preoperative incisors; orthodontic

intraoral leveling

photographs. Note the lack of paiatai of the mandibular arch is not necessary.

1973

impingement

In all cases, the deta,iied finishing movement and “‘settling” of teeth into a stable occlusion can be deferred until after surgery. 1t is almost impossible to obtain these detailed movements prior to the surgical procedure. The rationale for correcting posterior cross-bites and carrying out leveling by extrusion after surgery is simply that these procedures are both easier and more efficient at that time. After surgery, teeth are being moved without interferences from occlusion, whereas if these movements are attempted before the surgical procedures, the teeth may be moved into traumatic occlusion. The following case reports illustrate potential orthodontic-surgical interaction in specific circumstances. Cnse. 1. In this patient (Figs. 1, 2, and 3) the vertical position of the mandibular incisors was good, so that no orthodontic treatment of the mandibular arch was necessary. The mandibular incisors had not erupted into palatal contact. The maxillary incisors showed only mild irregularities. Transpalatal distance between the maxillary canines was too narrow to match the lower dental arch if the segment was repositioned posteriorly. Maxillary intercanine width was increased with a midline split at the time of surgery, and a removable appliance No further orthodontic treatment was was used to realign incisors slightly after surgery. required. Total treatment time was 4 months. Case 2. An anterior deep-bite relationship existed in this patient, in addition to the maxillary incisor protrusion (Figs. 4, 5, 6, and 7). Cephalometric analysis revealed a flat mandibular plane, so that leveling the lower occlusal plane and opening the bite by extrusion of posterior teeth was desirable. An acrylic wafer index was constructed on mounted dental

M!uxillary

Fig.

3. Case

1. Preoperative

and

postoperative

protrusion

cephalograms

and

in adults

375

tracings.

casts to maintain a slightly open bite at the time of surgery. The anterior maxillary ostectomy was performed, bringing the maxillary anterior segment posteriorly and superiorly to assist in the deep-bite correction. Mandibular occlusal plane leveling and maxillary incisor alignment xvere achieved after the ostectomy. Despite some difficulties lvhen a cast splint for fixation broke at surgery, a good result was achieved in 11 months. Cnse 3. In this patient (Figs. 8, 9, and 10) a maxillary lateral incisor was missing. The remaining five maxillary incisors had drifted, making prosthetic replacement of the missing lateral incisor impossible. Orthodontic correction of the incisor spacing problem was necessary before surgery. The mandibular second premolars were extracted to provide space for incisor alignment and leveling of the lower occlusal plane before surgery, while maintaining the anteroposterior position of the incisors. Leveling by a combination of premolar extrusion and incisor intrusion was expected. In this instance, since full orthodontic appliances were in place in the maxillary arch at the time of surgery, a rectangular stabilizing arch wire was employed for postsurgical fixation. The full-dimensional rectangular arch was bent on the prediction casts. An acrylic index was constructed on these casts to obtain the predicted position of the teeth at surgery, and the rectangular arch mire was tied to place in the operating room after the segment had been placed in the acrylic index. Preoperative orthodontic procedures required 8 months, and postoperative orthodontic finishing took 3 months. Total treatment time was 13 months, including the 2 months of postoperation stabilization. Case 4. A more complicated dental problem in addition to the facial deformity existed in this patient (Figs. 11, 12, and 13). Several permanent teeth had been lost, with subsequent periodontal problems. A periapical radiolucency secondary to nonvital teeth was discovered in the mandibular incisor region when the patient was first examined.

76

Profit

Fig.

and

4. Case

Am.

White

6. Orlhod.

October

2. Pretreatment

and

Case

Pretreatment

2.

1 year

posttreatment

and

posttreatment

profile

photographs.

casts.

1973

Maxillary

Fig.

6. Case

splint fractured, index controls Imaxillary and

2. A,

lntramaxillary

fixation

an arch bar segment vertical dimension. B, mandibular arches after

Fig.

7. Case

with

a cast-gold

splint

was substituted for Orthodontic bands surgical procedure.

2. Cephalometric

protrusion

was

in adults

planned.

When

377

the

the missing piece. An acrylic were employed to level the

tracings.

When periodontal, endodontic, and restorative needs must also be written into a eomprehensive orthodontic-surgical treatment plan, our experience with this and similar patients would indicate that the best treatment sequence to follow is: (I) emergency care as required, and preliminary periodontal therapy; (2) preparatory orthodontic care prior to surgery; (3) ostectomy; (4) orthodontic procedures as necessary to position teeth where they are finally desired ; (5) comprehensive periodontal therapy ; and (6) comprehensive restorative treatment. Such a sequence was necessary for this patient. In addition to necessary scaling and curettage, endodontic treatment with retrograde amalgam obliteration of the root canals was carried out on the mandibular central incisors prior to orthodontic treatment. The extreme extrusion of mandibular incisors indicated that leveling of the mandibular arch should be achieved as much by intrusion as possible, and the appropriate orthodontic mechanics were set up preoperatively. It was decided not to attempt correction of the posterior cross-bites. After orthodontic leveling of the mandibular occlusal plane, an anterior maxillary ostectomy was performed, employing a rectangular arch wire which was tied in place in the operating room for surgical fixation. Minor postsurgical adjustments in tooth position were

Fig.

8. Case

3. Pretrearment

and

1 year

posttreatment

facial

photographs

required, and the orthodontic appliances were removed II months after they were initially placed. Periodontal surgical procedures in all quadrants and restorative procedures were carried out after removal of the bands. In this case, the incisors were stable in the immediate posttreatment period, but recurrent periodontal disease and spacing of incisors mere noted on 3-year follow-up. Finishing,

orthodontic

retention

cmd

stability

If tooth movement has been deferred until after surgical intervention, it is important that everything be ready to begin tooth movement as soon as surgical

Number Volunae

4 64

Maxillary

Fig. 9. Case

3. Cephalometric

tracings,

orthodontic

in adults

protrusion

preoperative

379

preparation.

m. pntrtdrmntpost tredmd

. .. .._

,,‘1 : ;’ I’ ; ,’IL’,,1:: ,’,‘,? Q ‘,I .Fig. 10. Case.

3. Cephalometric

tracings,

total

treatlment

period.

fixation ean be released. An acrylic index will b’e in pl.ace during the healing period, so that the patient has a stable occlusion. This stability of occlusion is important, so the index should not be removed until the patient is comfortable with the new occlusal relationship that it creates and until healing has progressed to the stage that postsurgical fixation could be removed normally. When the index is removed, it is important that light working orthodontic arch wires be placed immediately with vertical and/or cross elastics to correct tooth

A-m. J. Orthod. October 1973

Fig.

R 1~ Case

4. Pretreatment

and

posttreatment

dental

casts.

position and simultaneousiy guide the ma.ndible to its desired position. If a patient has a tendency to slide the jaw forward after a maxillary ostectomy, the position of the maxillary incisor teeth mill not be stable. Orthodontic elastics and resulting tooth movement can be used to prevent this. If tooth movement has been accomplished prior to surgery the teeth should fit reasonably well at operation. Vertical elastics on light arch wires may be needed to obtain detailed interdigitation, but this finishing phase of treatment should take only a few weeks. Retention after a course of treatment which includes surgical retraction of maxillary incisors differs little from retention a.ftcr total treatment by orthodontic tooth movement. Once healing has occurred, the bony segments are remarkably stable.7* lo An>- instability is caused by the shifting of teeth within the alveolar process, not by shifting of the segments themselves. If anything, stability after surgical retraction is better than after orthodontic retraction of incisors. Frequently, no retention is needed after anterior maxillary ostectomy. If tooth movement besides the ostectomy has been achieved (alignment of incisors within the segments, for instance), the usual orthodontic retention procedures are indicated. Tongue adaptation to the new position of maxillary incisors after surgical

Volume Number

64 4

Maxillary

Fig.

12.

Case

4. Pretreatment

Fig.

13.

and

Case

2 years

4. Cephalometric

protrusio?z

posttreatment

in adults

381

cephalograms.

tracings.

retraction seems quite good. Lingual pressure studies indicate that pressure against incisors by the tongue tip tends to increase after retraction, but there is no tendency for teeth to flare toward their original position unless tongue pressure is tripled or quadrupled following operation.ll Fortunately, this occurs rarely with either surgical or orthodontic retraction. Summary

and

conclusions

In adult patients, anterior maxillary ostectomy can be used for retraction of protrusive ma,xillary incisors in a patient for whom other necessary tooth move-

382

Profit

and White

Am. J. Orthod. October 1973

inent is accomplished by conventional orthodontic full-banded therapy. The additional risk to the patient of the surgical procedure is minimal, and the risk of root resorption during orthodontic treatment is minimized because of the decreased duration of t,reatment. The shorter treatment period is the major advantage of using an ostectomy for incisor retraction. Other advantages are the maximum retraction of incisors which is achieved with the surgical procedure and the ability to intrude the maxillary incisor segment if needed. The primary disadvantage, besides the minimal risk associated with surgery, is the potential increased cost to the patient. Diagnostic criteria are not different if an ostect,omy is planned as part of the over-all orthodontic treat,ment. Surgical incisors retraction gives a slightly different nasolabial angle than orthodontic retraction of maxillary incisors. Cephalometric prediction of results is a key step in treatment planning, to ensure that all treatment possibilities have been weighed and also to prevent unexpected esthetic results. If orthodontic treatment is limited to minor reposit,ioning of individual teeth or to leveling of the mandibular arch by extrusion of canines and premolars, the orthodontic treatment can 1~2carried out entirely following the ostectomy. If extraction spaces in either arch are to be opened or closed orthodontically, or if some component of leveling of the occlusal plane by intrusion of teeth is required, this part oi’ the orthodontic treatment should be done prior to surgery. When. all maxillary teeth are banded prior to the ostectomy, a rectangular arch wire can be used to achieve maxillary fixation, without the necessity for tying the jaws together during the healing period. In all instances, final detailing of the occlusion orthodontically should be done following the osteetomy. Retention problems are similar, whether the incisor retraction was done surgically or orthodontically. The bony segments are remarkably stable, once healing has occurred, and repositioning of the teeth within the segment in response to tongue or lip forces is observed rarely. The maxillary ostectomy procedure offers a way to achieve excellent results for adult patients with maxillary protrusion in treatment periods consistently under 1 year. REFERENCES

I.

2. :1. 4. 5. 6.

Hogeman, K. E., and Sarnas, K. V.: Surgical and dental-orthopedic correction of maxillary protrusion or Angle Class II, Division 1 malocclusion, &and. J. Plast. Reconstr. Surg. 1: 101.10,7, 1967. K61e, H.: Surgical operations on the alveolar ridge to correct occlusal abnormalities, Oral Surg. 12: 277-288, 1959. Daniel, II. T., White, R. P., Jr., and Proffit, W. R.: Anterior maxillary osteotomy in dental treatment, J. Am. Dent. Assoc. 83: 338-343, 1971. Kent, J. N., and Hinds, E. C.: Management of dental facial deformities by anterior alveolar surgery, J. Oral Surg. 29: 13-26, 1971. Bell, TV. H. : Revaseularization and bone healing after anterior maxillary osteotomy : A study using adult rhesus monkeys, J. Oral Surg. 27: 249.255, 1969. deshields, R. A.: A study of root resorption in treated Class II, Division 1 malocclusion, Angle Orthod. 39: 231-244, 1969.

Maxillary ‘7. Bell, W. H., anterior part 64:

162-187,

and Dann, J. of the jaws-A

J.:

protrusion

in adults

383

dentofacial deformities by surgery in the and soft-tissue changes, AM. J. ORTHOD.

Correction of study of stability

1973.

8. McNeil& R. IV., Proffit, W. R., and White, R. P.: Cephalometric prediction for orthodontic surgery, Angle Orthod. 42: 154-164, 1972. 9. Harris, M. E.: Cephalometric prediction of soft tissue profile fa~llowing anterior maxillary osteotomy, thesis for Certification in Orthodontics, University asf Kentucky, 1973. 10. Knight, J.: Cephalometric study of stability after anterior maxillary osteotomy, thesis for Certification in Orthodontics, University of Kentucky, 1972. 11. Proffit, W. R.: Diagnosis and treatment planning for alveolar surgery, with special reference to soft tissue considerations, Proc. Third Int. Orthod. Congr., 1973. (In press.)

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society

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co-incident allready look the

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with features

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American

Society

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close

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Address,

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