Physiologic recovery after cervical traction therapy

Physiologic recovery after cervical traction therapy 1. Wieslander,

Portlnnd,

leg. tandliik.,

M.S.D., and D. 1. Buck, D.D.S., M.S.D.

ow.

T

changes of all dentitions with age is a well-known he continuing biologic phenomenon. That those few select persons who experience the benefit o F orthodont,ic therapy should not undergo t,his adaptation would be contrary to nat.ure’s laws. Therefore, we must accept the fact that relapse is a critical facet of our responsibility and, for the most part, not well documented. These posttreatment changes ha\-e been categorized as “ph+ologic recovery and developmental changes.“l While the influence of orthodontic forces on facial structures other than dentoalveolar structures has been the subject of quantitative investigations, the question of whct,her these alterations remain in the treated patient or are obliterated 1)~ later growth changes is only partly understood. Several studies deal with long-term effects of cervical traction on the maxillary facial complex in human beings and animals.‘. ‘j Two previous investigations revealed that such force upon the maxilla map influtlnce the facial growt,h pattern in a more posteroinferior direction, with an effect upon the location of the pterygomaxillarv fissure as well as the anterior nasal spinr! an(l the masillarp molars. Anatomic structures surrounding the maxilla were fount1 to be influenced with a slight change in nasion, a rotation of the sphenoid hone, and moderate influence on position of the mandible.“, R The purpose of the present study is to determine whether these accomplished orthodontic changes are relatively stable or whether phpsiologic recovery and developmental changes tend to eliminate the changes. Furthermore, t,hrough the use of a well-matched control group, a better understanding of the role of normal variation associated with these changes can be ascertained. Material

and

method

The material for this investigation consisted of Class 11 malocclusions, in both hops and girls, in the mixed dentition followed longitudinally to the age From University of Oregon Norrlandsgatan 294

Dental School. 31-33, Stockholm, Sweden.

Senior

author’s

present

address:

Volume Number

66 3

Fig. 1. Cervical traction as applied of which is inserted in molar tube.

Physiologic

with

recovery after

a cervical

strap

and

cervical traction

a face-bow,

the

inner

295

arch

of 18 years. A treatment group of twenty-eight patients wearing cervical traction”, i for 12 to 14 hours a day, with 10 to 15 ounces of force upon the maxillary molars for an average treatment time of 2 years 8 months, was utilized (Fig. 1). In certain instances, the maxillary incisors were banded and a bite plate was used during part of the treatment. Twenty-three patients in this group could be recorded at an average age of 18. In addition, it was possible to select a control group of twenty-eight untreated children, each of whom had a Class II malocclusion in the mixed dentition. This group was used to match the treatment result group. Twelve children in the control group were not treated orthodontically and could be recorded at age 18. The mean ANB difference was 6 degrees. The cases in the two groups were matched as closely as possible with regard to overbite, overjet, ANB difference, and molar relationship. It was possible to match individuals very closely for dental-development age, sex, and time of observation.” I’or each case studied, one cephalometric film was taken at the start of observation at an average age of 9 years. A second cephalogram was taken approximately 3 years later. To be able to study stability or relapse of recorded changes after treatment, a third cephalogram was taken at the average age of 18. The three stages of observation were referred to as “pretreatment,” “posttreatment,” and “postretention.” Tracings of cephalometric films were performed according to an accepted standard technique. To be able to study changes in position of the maxilla and ment study

*We are indehted to Richard A. Riedel, Seattle, Wash., group, and to Bhim S. Savara, University of Oregon the control group.

for permission Dental School,

to study his treatfor permission to

296

Il’eislmtder

Fig. 2.

Control

Am. J. Orthod. September 1974

md Buck

group.

Mean

changes

recorded

at

the

ages

of

9,

12,

and

18

years.

. ....

-AGE 9 ----AGE 12 AGE 18

Fig. ment

3.

Cervical (age

12),

traction and

group.

postretention

Mean (age

changes

recorded

pretreatment

(age

9),

posttreat-

18).

the structures surrounding the maxilla, we used a special area for superimposition of subsequent films for reasons described in a previous study.5 Anatomic structures of the anterior cranial base, with the most posterior point of the posterior outline of the frontal sinus, were used for reference purposes. Growth changes in this area have recently been studied, and it appears to be acceptable

Physiologic

recovery after

cervical traction

297

\ AGE 18 I.........CERVlC& l-R/jCTlON “‘.L ....,__ “X..,, CONTROL -.. .. . ...)..

Fig. 4. Schematic group and the

diagram of differences control group at age 18.

in mean

CONTROL

changes

3, : - . . ..._:>* ,/,.. :i’

between

the

cervical

traction

CERVICAL TRACTION

KG

\(I\ ‘*

1: 4\ Fig. 5. 12, and

A comparison 18 years in the

of schematic cervical traction

‘romm’

‘10 I diagrams of. mean group and the control

changes group.

at

the

ages

of

9,

Table

I. A

comparison

of

change

in the

t

I’oirrt .I .\NS P:rlat:11 plxw

2.06 J4.94 +1.56”

S:tsim

J1.05

rohtiou

-.L>(j2 +O.W”

Masilhrp molxr JZ:\ndilml:rr plane

1.“5 pi3 t 2.i 1 +1.2n”

Mrntorr

wnI- *1NL;1 ‘Significant

0.70 p.17

e-3 “29

the

control

group.

Arrows

I .3fi

3.67

j,X.ii

1.i;

1.17

1.41" 0.8ti

+o 5i" p:02

1. .15" 0.5x

0.99" I .03

3.27

1.18

c O.il

0.x3

1.91

;.oo*

127"

-0.65"

126"

1.64"

1.81"

1.61

9.12* t’,Sfj” 2.M ?.

t1.29

O.li

2. 21

J3.85 + 2.50 -0.49”

1.57 I .X-l”

--a Poyonioll

and

--7,

t

WI\1 to sphenoitl Masilhry mo1:11

group

1.61 1 .(iG

t

1”I’M Sphcnoid

headgear

2.10 !L%i

1.3“

+ 1.71 /i.O3

++ 2.9;

0.92

1.08”

!!.t%

1.08

3.5Y 1.66

“.I?! 1.3;”

3.21

10.41”

1.58”

:j,6:j”

2.1 1 :I.;, 1

1.01 2.1-I

2.46%

I.38

0.68

1.x9

l.iS

at the 0.05 level of confidence.

for rcft~rcnw of’ this ~lvsig!:IP In atltlition. tlic Koltotl point was rcgisteretl fol orientation of the rcfcrence lint>. Mcasurement,s wre rrwwtled in relation to il grid systrm originated 1)~ the Frankfod horizontal. The grid system was transftwcd from the first, traving to t,he sccon~l and third tracings, so that all mcasuwm~nts rcfcrrcvl to the area of sul)criml)c’sit,iori (E’igs. :! and 3) Jlwsurtwicwts wcw rrcortlrcl t,o lhc nearest 0.1 mm., anti iwutine statistical wwtvlurcs wre utilizcvl. Any statistical tliffcrcncc lwtwcn the control group iIlI(l the trcatetl ~roul) was consitleretl as thw to treatnlcnt t3cct. The stan(Iarc error of t,hc mcasurc for horizontal and \-crticd vhangw was 0.5 mm.

170Zunse 66 Nnmber 3

demonstrate

t’h~ysidoyic

the

direction

of

change,

Pretreatment llendgcar

either

(age

n=d3 ,F

-3.17” 0.38

IY:iGC t

after or

(age

cervical

299

superoinferiorly

18)

dX1 -0.51”

traction

n=ld

-2is I.i6”

t J7.27

an teroposteriorly

9).postrctention Control

1s

rccwery

t

1.10”

2.66"

4.76"

+ 2.69

1.80

3.51

4.06"

2.04

J6.68

3.13

2.08

0.59

0.79

1.88"

-0.31"

1.43"

1.08"

1.74

1.15

$0.57

0.73

0.70

1.93

t

3.30

1.52

1.4i

1.09

1.83

3.71"

+0.44O

2.06"

-2.15"

2.27"

2.5g0

2.26"

t

c

2.45

2.24

Ll2.66 t

1.76

1.76

2.53 2.26'

-0.17" -3

0.56

1.71

1.89

4.07"

3.02

0.33

0.32

5.35

1.82

7.11

4.34"

-2.31"

1.85"

2.14"

2.82"

J12.33 -3

+

3.00 J16.14

3.55 4.40

4.83 J15.15

2.85 4.10

1.83 0.99

1.54 0.65

cs 4.26

2.76

z3

1.75

0.67

0.76

Cervical traction treatment of Class II malocclusion in the mixed dentition may change the growth pattern of the maxilla in a more posterior-inferior direction (Table I, Figs. 2 and 3). After treatment, the downward and forward growth tendency continued to an equal extent in both the treated group and the control group. Thus, in effect, the spatial change in position of the maxilla in relation to surrounding anatomic structures as an effect of treatment appeared to be quite stable (Fig. 4). The difference in the position of point A betnccn the two groups was evident to the same extent at postretention observation as after active treatment. Retluction of the ANB angle and the more posterior position of PTM as a result of treatment were also findings that could be recorded at age 18. However, the observed slight tipping of the palatal plane and inferior movement of the anterior nasal spine posttreatment was evident to lesser extent postretention, and no statistically significant difference was found. The same was true for nasion, which revealetl a slightly more inferior position after treatment, but posttreatment development decreased the difference between the two groups (Fig. 5). The effect of treatment on the sphenoid bone, with a more posterior position of the pterygoid process as well as a clockwise rotation of the base of the sphenoid bone, was relatively stable and quite evident at postretention age 18 (Fig. f-5).

AWL. J. Orthod. September 1974

/ CERVICAL TRACTION

CONTROL

Fig.

6.

and

18 years

A

comparison in the

of

schematic

cervical

traction

diagrams group

and

of

mean

changes

the

control

group.

at

the

ages

of

9,

i2,

The estahlishetl Class 1 molar relationship was accomplished by distal movement, of the maxillary molars due to the dentoalveolar response to force and to change in the position of the maxilla. An increased difference in posterior position of the maxillary molar was, however, observed at age 18. Dcwel” states that “the purpose of early Class II treatment is (1) to prevent a further extension of the existing malocclusion and (2) to restore or cstahlish normal occlusal relations of the teeth so that the clentition mill have a better chance to follow a normal developmental course in the future.” The interruption of unfavorable dental development with improved muscular and occalusal relationship may have influenced the growth pattern of the maxillary molars after treatment with this subsequent more distal position at the postretention time point (Fig. 6). The distal movement of maxillary molars may affect the position of the mandible. The slight clockwise rotation of the lower jaw observed after treatment was noticeable to some extent at postretention observation, with a steeper mandibular plane in the treatecl group than in the control group. There was, however, no statistically significant difference in the position of pogonion between the two groups (Fig. 6). Accomplished changes in position of the maxilla ant1 surrounding anatomic structures due to cervical traction in the mixed tlentition revealed an over-all picture of relatively gootl stability with a minor tenclency for posttreatment change.

Summary

and

conclusions

A longitudinal investigation ot’ Class II malocclusions treated in the mixed dentition with cervical traction was undertaken in an attempt to study phpsiologic recovery and developmental changes after treatment. A well-matched group of untreated Class II cases was used as a control. It is gratifying to document that changes in the posterior movement of the maxillary molar, the basal maxillary changes revealed by point A and PTM, and the surrounding anatomic structures demonstrated by rotation of the sphenoid bone are relatively stable. Change in position of the maxilla affected the mandible, and a slightly steeper mandibular plane angle could be recorded postretention. The corresponding posterior displacement of pogonion, however, was not statistically significant. The statistical testing of these various hypotheses, plus the magnitude of the growth and treatment differences, tend to indicate clinical significance of these data. The maxillary molar, the base of the maxilla, and associated facial structures demonstrated minimal physiologic return after a six-year followup of treatment changes. REFERENCES

1. Horowitz, S. L., and Hixon, E. H.: Physiologic recovery following orthodontic treatment, AM. J. ORTHOD. 55: 1, 1969. 2. Mitani, H., and Brodie, A. G.: Three plane analysis of tooth movement, growth and angular changes with cervical traction, Angle Orthod. 40: 80, 1970. 3. Moffett, B.: University of Washington School of Dentistry, Department of Orthodontics, Personal Communication, 1973. 4. Wieslander, L.: The effect of orthodontic treatment on the concurrent development of the crnniofacial complex, AM. J. ORTHOD. 49: 15, 1963. 5. Wieslander, L.: The effect of force on crania-facial development, AM. J. ORTHOD. 65: 531-538, 1974. 6. Kloehn, S. J.: Guiding alveolar growth and eruption of the teeth to reduce treatment time and produce a more balanced denture and face, Angle Orthod. 17: 10, 1947. 7. Kloehn, S. J. : Orthodontics-Force or persuasion, Angle Orthod. 23: 56, 1953. 8. Knott, V. B.: Ontogenetic change of four cranial base segments in girls, Growth 33: 123, 1969. 9. Demel, B. F.: Objectives of mixed dentition treatment in orthodontics, AM. J. ORTHOD. 50: 504, 1964. 611 S. UT. Campus

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