Facial growth: Before, during, and following orthodontic treatment James
he orthodontic clinician is interested in facial growth as it relates to his endeavors. His primary objective is the correction of the dental abnormality and this is generally accomplished in the growing child. This raises a question which has been a great torment for the specialty. Should the clinician confine his efforts to rearranging t.he teeth or should he also attempt to alter facial growth P This study presupposes that modern orthodontic appliances can accomplish the dental correction. It is concerned with whether orthodontic treatment can change the facial growth direction. A comparison of growth direction before, during, and after treatment would be beneficial in such a determination. This, therefore, is a longitudinal study of several individuals before, during, and following orthodontic treatment. Review
Various terms have been used to describe how orthodontic treatment affects facial growth. These include stimulation,lo, 15, *I inhibition,+ I89*I retardation,8, lG redirection, correction,g and guidance.ls The use of such terminology indicates that growth manipulation is a possibility and that the orthodontist may have this capability. Hixon and KleinI did not agree with these ideas on the capability of growth alteration. They stated: “After three quarters of a century in which a large segment of orthodontic treatment has been directed toward bone growth or inhibition of growth, it is interesting to note there is not one study known to either of us which has broken the null hypothesis.” They further stated: “. . no orthodontic appliance has been shown to produce clinically meaningful (more than 1 mm.) long-term changes in the facial skeleton.” Investigations of facial growth were generally done by two methods. Those investigations involving orthodontic treatment were often done by comparing the growth of a treated group to the growth of a control group. Those investiga68
tions not involving treatment were often done by longitudinal growth studies of individuals. Investigations by Poulton,25 Weislander, and KleinI’ reported more downward tipping of the palatal plane and less forward movement of anterior nasal spine in the groups treated with cervical traction than in the control groups. Creekmore,l” Moore,21 Poulton,2”, 25 Silverstein, and Hanes’* reported less forward movement of pogonion in groups treated with cervical traction than in the control groups. Creekmore”’ also reported more vertical growth of anterior facial height in the treatment group than in the control group. These investigations revealed differences between two groups rather than the alteration of growth of an individual. Investigations of facial growth not involving treatment were concerned with either growth direction or growth rate and were generally longitudinal in nature. Broadbent, Brodie,G and DownsI’ concurred that facial growth occurred primarily along straight lines in an “orderly and uniform” manner. Bergersenl followed various profile landmarks from infancy to adulthood on a sample of sixty subjects. He found ANS and menton to migrate along fairly straight lines. Although growth directions of the individual were consistent, there was a wide range of directions between individuals. He found a positive correlation between growth directions of ANS and menton. When ANS had a steep inclination in growth direction, menton also had a steep inclination. Pike’” studied the growth rates of different parts of the face on a sample of twenty-five persons from the age of 7 years to the age of 12 years. He found that “all individuals demonstrated a close approximation to linearity (constancy) in the growth rates of statural and facial skeletal dimensions studied.” “Deviations in rates of growth observed in this investigation were due to minor alterations from a constant rate of growth and to technical errors in obtaining the data.” Hunterl” and Bergersen’ reported a “growth spurt” (acceleration and deceleration of rate) of the face in adolescence. The foregoing material implies that facial growth, while it may not occur with mathematical precision, is at least an “orderly and uniform” process for the individual. No studies were found which compared an individual’s facial growth before treatment with that individual’s facial growth during treatment. Several investigations reported a low correlation between facial growth and the dentition. Bj6rk4 found a low correlation between overjet and maxillary growth, overjet and mandibular growth, and overjet and the difference between maxillary growth and mandibular growth. Maj and Luzilg reported a low correlation between overjet and the difference between maxillary and mandibular growth. They also found a low correlation between overjet and mandibular plane angle. WilliamsZ9 found a low correlation between various growth measurements and changes in dental occlusion. He found “no evidence to support the belief that good mandibular growth will correct an excessive overjet and/or a Class II relationship.” Of sixty-six subjects examined at approximately age 7 and again approximately at age 14, forty changed molar relationship by one half width of
Am. J. Orthod. January 197i
DIHECTlON lLIOVEMENT OF ANS, PO AS RELATED TO FII
transfer the of
of 8 mm.
measurements forward of
in millimeters. the
3 mm. to
superimposing and ANS
movement 3 mm.),
is represented length
by arrow the
a cusp. One subject out of sixty-six changed from a C’lass II relationship to a Class I relationship. Twenty-fire subjects did not change molar relationship. There were no significant differences in growth of the group that changed molar relationship and the group that did not change molar relationship. There is another factor which has a bearing on the final shape and size of the face. This is a phcnomcvlon called mantlibular rotation. Bjiirk” studied mandibular rotation on 213 Swedish boys examined at 12 years of age and again at 20 years of age. He found that both forward and backward mandibular rotations had occurred. With forward rotations, he stated, “the mandibular symphysis swings forward and the chin becomes more prominent.” With backward rotations, he stated, “the symph,vsis swings backward and the chin is clrawn back below the face.” “ Backward rotation of the mandible is less frequent than forward rotation and has been examined by the implant method in considerably fewer subjects.” Odegard” investigated mandibular rotation in connection with orthodontic treatment. He reported more rotation with removable appliances than with no treatment, and more rotation with fixed appliances and face-bow than removable appliances. Hc concluded, “treatment probably causes a change in the position of the mandible and not in mandibular morphology.”
pretreatment During range
varied for the
in growth the
Tweed” also noticed cases in which mandibular rotation occurred during treatment. The FMA became more obtuse and b point dropped down and back during treatment. This was in contrast to his measurements of the FMA closing an average of 5 degrees from childhood to adulthood. Methods
The sample consisted of nineteen subjects with at least one phase of treatment and at least one phase of nontreatment. These phases were monitored by serial cephalometric head films. Orthodontic treatment was accomplished by the use of an edgewise appliance. Auxiliaries included cervical traction and face-bow to upper molars, high-pull headgear and face-bow to upper molars, straight-pull headgear attached to anterior section of arch wire, high-pull headgear attached to anterior section of arch wire, and intermaxillary elastics. The head films were traced and sella, anterior cranial base, maxilla, mandible, orbitale, and porion were outlined. The original porion was transferred from head film to head film and used throughout the series for each individual. A template of maxillary anatomy was constructed for each individual and this was used to maintain a constant relationship between ANS and maxilla. Each tracing had a different Frankfort plane (due to slight movement of orbitale away from anterior cranial base) and the Frankfort plane from the last film of the
411~. J. Orthod. January 1977
DIRECTION MOVEMENT AS REIu TED I’0 FRANKI Patient
OF ANS, PO RT PLANE
Pre Treatment Byrs.
hxiliaries ta rting: AFce ANS CT FB Age 7$
4yrs. ANS PO
No Aux. Age 9
CT FB Age 11
1, 2, 4,
auxiliaries 3, 7,
8 are of
examples All deviation.
9 is most
1 is most
in a clockwise with
CT FB, cervical
No Aux. Age 10
3, A and B. Auxiliary SP HG, straight-pull
Syrs. lmo, .
lyAr-. 1 Omo.
St. Pull HG Hi Pull HG Age 10
2grs. 2. CT
Post Treatment 3 yrs.
Treatment J-yr. 2mo.
CT FB Age 8
k \ 3vrs. ANS
St. Pull HG Age 10s
St. Pull Age 9
\ Svrs. 7mo.
3, B. For legend,
1 / see opposite
each phase was used for comparison of direction. Movements of the points ANS and pogonion were measured in relation to the Frankfort plane. These movements were transferred to a graph. The graph was examined and comparisons were made treatment, and posttreatment of their directions during the pretreatment, phases. Findings
Pretreatment phase. There was an individual variation in growth direction and the range was fairly large. As compared to Frankfort horizontal, the individuals varied in direction of movement of ANS from 0 (horizontal) to 90 degrees
(vertical). Thr individuals v:iri(>tl in tlirwtion of movement of pogonion from 20 90 tlegrres. When ANS had a steep inclination, pogonion also hat1 a sttq inclination. The two points morctl in apl’ro?timatr~l~- ~~aral ICI tlirrctiolls. Twwtvled ~d~rw. There was an intlivitlual variation in movcmcnt of points AXS and pogonion tluring the twatment l~hasc. The intlivitluals varied in tlirw tion of movement of ANS .froni 46 to 165 tlcgrecs. 111 cliwction of movement of pogonion, the tlirrctioil ranged from slightly forwarcl of vertical (59 tlt~gretY+j to slightly backwartl of vertical (135 tlcgrrcs i Thew xas an incli~%luaI v;lriatiolr in wsponst~ to twatment. Several hat1 no change of tlirwtion ilr movcmont of’ Iwints ,1NS al1t1 pogonion during t,reatlnellt. Several hat1 il tleviiltioll iir tliiwtioii of 1iiowni~i~t of tlicsc points during treatment. The deviation was clockwise in natuw. The tlirwtion ehangctl from horizontal to vertical or f~~~nl vcrtiwl to slightI>- l)it~k\\-a1~(1of wrtical. AI types of ausiliaric3 wwr associatctl with this I~~JO~ISC owasionally. li:dgcwisc treatment Iv-it11no auxiliaries also protlucecl this wsl~onse owasioiially. The mowmtwt of ASS ant1 Iwgonioll again tcntlctl to OWIII~ in parallel clirwtions. 1Vhen ANS sto~~~~ctl its forwrtl movcmcnt, pogonion did also. \Vhcn ANS turned do\~nwai~t in tlirwtion, 1Jogonion tlicl too. Yosttrccrt~~e~f phase. T~~IY: was an intlividual variation in direction of movemerit of ANS and pogonion. J)urin g the posttreatmcnt phase t,he individuals varied from 0 degree ( horizontal ) to 90 clcgrtw (vertical ) for both .2NS antI poponion. (:cnerally, tlitl movenicnts of ANS illld pogonion wcw similar to their movcments during the pretwatment phase. 111scvcral cils(ls there was no movement of ANS, indicating a wssation of miclfw~ial growth (luring the treatment phase. ANS and pogonion again tended to move in parallel directions. to
The i~e~ura~~ oi’ wphalomctric stutlics tlepends UIJCJU ;I number of variables. Included among these are wnsistency- of equipment, film, exposure, development, centric relation, pat,icnt heat1 position, anal tracing. lnconsistcn~y in any of these prcclutles a high &grw of accuracy. Thus. minute changes ill dimension between cephalomctric tracings shoul~l not be wllsi(lerd as completely reliable. Changes greater than 2 1nn1. woultl ha\-(1 slightly more rcIiabilit!- an(I w)uId ]JCZ considerccl as having ;I nlodcl*i~t(~ tlegrec of accuracy-. &lost of the> hwd films in this study were exposed at intervals of 2 or inow J-ears in order to provide a relatively large dimensional change. The lack of uniformity of treatment is ii real problem in wphalometric studies of persons involving orthodontic treatmcbnt. Mcrrificltl ant1 Cross”” found that the direction of force varies not onl,v for the tliffcrcnt headgears but also for the same type of hcatlgeai~ 011 tliffcrcnt individuals. Another variation is in the amount of force Of tllca headgear. This CilII vary from il fe%V ounces to a few pounds. Still another variation is the amount of time 111~headgear is worn. This can vary from no hours to hundreds of hours, ant1 there is no arcurate m&hod of determining the amount. \Vith this many variables, it c’an IJC seen that it would IJC
difficult, if not impossible, to find a sample with any degree of uniformity of treatment. This would make it difficult to associate treatment with any particular growth response. In this study the type of auxilliary was noted for information only. The primary interest was in determining the effect orthodontic treatment in general had upon the growth direction of the individual. The term facial growth was interpreted to mean an increase in size of the face. The downward movement of pogonion was considered to be an increase in the vertical dimension of the face. The forward movement of ANS or pogonion was considered to be an increase in anteroposterior dimension of the middle or lower face. The term downward was considered to mean at a right angle to and below Frankfort horizontal. The term forward was considered to mean parallel with Frankfort horizontal and in an anterior direction. The direction of movement of the facial landmarks depends partially upon the selection of the point of superimposition. For example, superimposition on the bottom of the feet projects a child’s growth in an upward direction. Superimposition on the top of the head projects the child’s growth in a downward direction. The same rule holds true for the face. Superimposition on the upper part of the face projects facial growth in a primarily downward direction. Points of superimposition used in this study were sclla and anterior cranial base, and these were located along the upper posterior border of the face. Therefore, the primary direction of movement of the facial landmarks was downward and forward. The points were selected for accuracy of location. Another problem confronting the clinician is deciding what constitutes normal growth. An early concept” was that normal mandibular growth was downward and forward in direction. In 1966 Bergersenl measured the direction of facial growth on a sample from infancy to adulthood. He found the direction to vary from one individual to another. He also found the growth direction to be fairly consistent for the individual. In the present study the directions of movements of pogonion and ANS were measured in the pretreatment phase. This was considered to be the normal direction of growth for this individual. A major deviation in growth direction during the treatment phase was considered to be related to treatment. This method of investigation was considered more relevant than computing the average inclination and average deviation for the group. That computation would have implied that one could expect a moderate response from each individual. Such was not the case. Some individuals had a severe reaction, and others had no reaction. Several phenomena occurred simultaneously, and these were called collectively the “clockwise response.” They included retardation of forward movement of ANS as described by Creekmore,l” Poulton,a4, 25 Moore,“l and others; the tipping of the palatal plane as noted by Poulton,24 Weislander,2s and KleinIT; less forward movement of pogonion as reported by Creckmore,1° Moore,21 and PoultonZ4, 25; and backward mandibular rotation as noted by Odegard.” These phenomena occurred together and were referred to as the “clockwise response.” Several individuals of this study experienced the clockwise response to orthodontic treatment. Several had no apparent growth response to orthodontic treatment. None exhibited growth correction or improvement.
Am. J. Orthod. January 1977
Orthodontic treatment during the mixed-dentition stage is advocated for the dual purposes of correction of the malocclusion and correction of the growth. It is suggested that these are actually two separate objectives and that each should be evaluated on its own merits. There arc several factors which cause one to doubt the merit of growth-correction procedures: ( 1) There is not a great deal of facial growth to control ; many faces have only minute amounts of growth during treatment. (2) The relationship between facial growth and changes of the dentition is extremely tenuous; Bjiirk,4 Maj and Luzi,‘” and Rilliams”” found a low correlation between facial growth and the dentition. (3) Orthodontic trcatment did not actually improve facial growth; faces grow as well (or better) before treatment as during treatment. It should be emphasized that this study was concerned with facial growth as defined by an increase in the vertical or antcropostcrior dimensions of the face. It was not concerned with changes in the dentition. Yet ideas involving growth control often involve the dentition. For example, Kloehn’” statetl that his idea was that “treatment moved the maxillary teeth distally while face and mandible were growing in their normal path downward and forward.” Coben!’ spoke of “holding or retarding maxillary dentoalvcolar development and distally redirecting the vector of eruption of the maxillary teeth, as normal mandibular growth carries the lower teeth downward and forward into a Class I relationship.” These author9’ lR referred not only to growth changes but to changes in the dentition. dn attempt was made to separate the two subjects and only growth was examined. This study showed that not all “normal mandibular growth” is downward and forward. In the pretreatment phase, the direction varied from almost horizontal to vertical. This study also found that there was lit,tlc “forward mandibular growth” during treatment. I’ogonion, during treatment, moved primarily in a downward direction with either a slight forward or slight backward inclination. There was evidence of retardation of “forward development of middle face” but this was accompanied by retardation of forward movement of lower face because of the concomitant mandibular rotation. The effect on the individual was to increase vertical facial height and to decrease prognathism of the middle and lower face. Whether these changes were suffieicnt to make a significant difference in the size or shape of the face was not known, but the changes were not considered to be of a beneficial nature. There was no evidence of growth “guidance” or “correction.” Whatever benefits accrue from orthodontic treatment appear to be in area of alteration of the dentition rather than alteration of facial growth. This study reiterates the idea of variat,ion in hurnan characteristics. Dentitions vary in occlusal relationships and changes in occlusal relationships. Faces vary in size and shape. Growth varies in tlirection and rate. Thus, it is not surprising to find variation in facial growth response to orthodontic treatment. Many individuals do not conform to a mathemat,ical mean or average, and individual variation is common. Because of these variations, it is difficult t,o predict individual growth response. Summary
A longitudinal growth study was done on nineteen persons, involving three types of malocclusion and several types of treatment. Facial growth direction of
the middle and lower face was compared during pretreatment, treatment, and posttreatment phases of the individuals. The individuals in the sample varied in direction of facial growth. Some individuals had an almost horizontal growth direction, and others had a vertical growth direction. The individuals in the sample varied in their degree of response to orthodontic treatment. Several had no change from their normal growth direction. Several had a deviation in direction associated with orthodontic treatment. The deviation was clockwise in nature and the direction changed from horizontal to vertical or from vertical to slightly backward of vertical. Middle and lower face tended to move in conjunction during all phases. If ANS moved in a horizontal direction, pogonion tended to move in a horizontal direction. If ANS moved in a vertical direction, pogonion tended to move in a vertical direction. If ANS stopped moving forward, pogonion stopped moving forward.
1. Not all faces grow in the same direction. Some faces grow zontal direction, and others grow in an almost vertical direction. 2. Not all faces have the same growth response to orthodontic maintain their original growth direction, and others experience tion in response to treatment. 3. The clinician should confine his efforts to correction of rather than attempt to correct facial growth.
in an almost horitreatment. Some a clockwise deviathe malocclusion
1. Bergersen, E. 0.: The direction of facial growth from infancy to adulthood, Angle Orthod. 36: 18-43, 1966. facial growth spurt: Its prediction and relation 2. Bergersen, E. 0.: The male adolescent to skeletal maturation, Angle Orthod. 42: 319-338, 1972. 3. Bjiirk, A.: Prediction of mandibular growth rotation, AM. J. ORTHOU. 55: 209-233, 1969. 4. BjBrk, A.: Variability and age changes in overjet and overbite, AM. J. ORTHOD. 39: 779, 1953. 5. Broadbent, B. H.: The face of the normal child, Angle Orthod. 7: 209-233, 1937. 6. Brodie, A. G.: Some recent observations on the growth of the face and their implications to the orthodontist, AM. J. ORTHOD. 26: 741-757, 1940. 7. Brodie, A. G.: On the growth pattern of the human head from the third month to the eighth year of life, AM. J. ORTHOD. 68: 209-262, 1941. 8. Coben, S. E.: Growth and Class II treatment, AM. J. ORTHOD. 52: 5-28, 1966. 9. Coben, S. E.: The biology of Class II treatment, AM. J. ORTHOD. 59: 470.487, 1971. 10. Creekmore, T. D.: Inhibition or stimulation of the vertical growth of the facial complex, its significance to treatment, Angle Orthod. 37: 285-297, 1967. their significance in treatment and 11. Downs, W. B.: Variation in facial relationships, prognosis, AM. J. ORTHOD. 34: 812-840, 1948. 12. Hanes, R. A.: Bony profile changes resulting from cervical traction compared with those resulting from intermaxillary elastics, AM. J. ORTHOD. 45: 353-364, 1959. 13. Hixon, E.: Growth of the dentition and its supporting structure, J. Am. Dent. Assoc. 82: 782, 1971. 14. Hixon, E., and Klein, P. : Simplified mechanics : A means of treatment based on available scientific information, AM. J. ORTHOD. 62: 113-141, 1972. 15. Hotz, R. P.: Application and appliance manipulation of functional forces, AM. J. ORTHOD. 58: 459-478. 1970.
16. Hunter, C. J.: The correlation of facial growth with body height and at adolescence, Angle Orthod. 36: 1969. 17. Klein, P. L.: An evaluation of cervical traction on the maxilla and manent molar, Angle Orthod. 27: 61, 1957. 18. Kloehn, R. .J. : Guiding alveolar growth and eruption of teeth to reduce produce a more 1)alanced denturr, Anglr Orthod. 17: 10-33, 1947. 19. Maj, G., and Luzi, C.: Variation of the overjet and overbite in normal and 17 years, Eur. Orthod. Rot. Rep. Congr. 43: 225, 1967. 20. Merrificld, L. I,., and Cross, J. a. : Directional forors, Ant. J. ORTIIOIL 21. Moore, A. W.: Olwrrations of facial growth and its clinical significance, 45:
24. 25. 26. 27. 28. 29.
Mandilwlar rotation studied with the aid of metal implants, A&I. J. ORTIIOI). 1970. Pike, J. B.: A serial investigation of facial and statural growth in seven to twelvr year old children, Angle Orthod. 38: 63-73, 1968. Poulton, I). R.: A three year survey of Class II malocclusion with and without headgear therapy, Angle Orthod. 38: 181-193, 1964. Poulton, D. R.: The influence of cx?raoral traction, tiM. J. ORTH~D. 53: 8-18, 1967. Silvwstcain, A.: Changes in tile bony facial profilr coincident with twatment of Class II Division 1 malocclusion, Angle Orthod. 24: 214-237, 1954. Tweed, C. FT.: Clinical Ort,hodontics, St. Louis, 1966, The C. 1’. Mostly Company, ~01s. 1 and 2. Weislander, I,.: The effect of orthodontic treatment on the concurrent development of the craniofacial complex, AM. J. ORTHOLL 49: 15-27, 1963. Williams, R. E.: The influence of jam growth on molar position, overjet ant1 mandibular plane angle, Certificate Thrsis, University of Oregon Dental School, 1971. 58: