Oral Orthopedics and Movement of Maxillary Segments

A Roentgen Stereophotogrammetric Study

BODIL RUNE, D.D.S.

KARL-VICTOR SARNAS, D.D.S.

GORAN SELVIK, M.D.Lund, Swedgn

An infant with a complete unilateral cleft of the lip and palate underwent maxillary

expansion treatment using an oral orthopedic appliance. Movement of the maxillary

bone segments was studied by means of metallic implants and roentgen stereophotogrammetry,

and intra-oral changes were recorded by measuring transverse dimensions on casts.

Expansion treatment had almost no influence on the positions of the maxillary segments,

and movements of the segments showed little agreement with measures on casts. The

findings suggest that the appropriate use of the term oral orthopedics and the evaluation of

treatment effects would benefit from evaluating the movement of the segments by

methods other than measurements of casts.

Introduction

"Oral orthopedics" is a term used "to con-

vey that a different type of movement is

achieved by certain appliances, i.e. a move-

ment of the entire jaw segment, tooth, bone

and soft tissues, as one unit," (Robertson and

Hilton, 1971). Treatment results have been

evaluated mainly by measuring series of casts

to determine intra-oral changes (Huddart,

1961; Graber, 1964; Huddart, 1967; Neuman,

1967; Robertson and Hilton, 1971; Huddart,

1974; Robertson and Fish, 1975; Robertson,

Shaw, and Volp, 1977; Shaw, 1978). Mea-

surement points are poorly defined, however,

and are difficult to identify because of rapid

changes in surface morphology and tooth

eruption. Besides, appositional growth and

remodelling disguises displacement of the

bone segments. Movements of the segments

can not, therefore, be accurately identified by

means of surface measurement points.

To obtain identifiable measurement points

in the infant maxilla, metallic implants have

been inserted and used as bone markers in a

few roentgen studies (Robertson, and Hilton,

1968; Robertson, 1971; Robertson and Hil-

Dr. Rune is Orthodontist at the Center for Craniofa-

cial Anomalies, General Hospital, Malmo, Sweden and

Dr. Sarnas is Orthodontist and Head of the Center at

the same hospital. Dr. Selvik is Assistant Professor at the

Department of Anatomy, University of Lund, Lund.

The study was supported by grants from Segerfalks

Foundation, Helsingborg.

ton, 1971; Robertson, Shaw, and Volp, 1977;

Shaw, 1978). Implant stability, however, was

not ascertained in the two-dimensional coor-

dinate systems, and Shaw (1977) stated that

the implant technique "is of limited value

since the implants may be disturbed by the

developing teeth and because slight inaccu-

racy in head positioning may lead to substan-

tial errors of interpretation."

Since exact methods for recording move-

ment of the maxillary bone segments in in-

fants have been unavoidable, it has been im-

possible to verify the claims which have been

made relative to the effects of oral orthope-

dics.

With a recently developedroentgen ster-

eophotogrammetric method (Selvik, 1974)

based on the use of metallic implants, move-

ment between bone segments is recorded

three-dimensionally. Implant stability is

checked with a high degree of accuracy, and

the need for identical head positioning is elim-

inated (Rune et al., 1977 a; Rune et al., 1977

b). In the present study this method was used

to record movement of the maxillary bone

segments in an infant who underwent oral

orthopedic treatment prior to primary palate

repair.

Materials and Methods

The study concerns a girl with a complete

cleft of the lip and palate on the right side.

Surgical treatment included primary lip clo-

385

386 Cleft Palate Journal, October 1979, Vol. 16 No. 4

sure (lip adhesion) at about three months ofage; primary palate repair (Wardill proce-dure) at about 20 months; and secondary liprepair (Randall-Johanson procedure) atabout 27 months. Prior to primary palaterepair, maxillary expansion treatment wascarried out by means of an acrylic plate witha fan screw. After surgery, the infant refused

FIGURE 1. Locations of implants. L, inferior ridge

of the infrazygomatic crest. 4, anterior aspect of themaxilla, medial to and at the level of the infraorbitalforamen. P, oral aspect of the palatal shelf, halfwaybetween the incisive foramen and the transverse palatinesuture.

mm |primary lipclosure

o

primary palaterepair

+60-LU

+5.04'

+4.0

+304

+2.04

+1.04

o 4

-1.04

-2.07 expansion

---

-3.0-

to wear the retention appliance, and no fur-

ther orthopedic treatment was attempted.

Imptants. Tantalum implants (pins 1.5 %

0.5 mm) were inserted in each maxillary seg-

ment at the time of primary lip closure at

locations previously described (Figure 1)

(Rune et al., 1977 a).

ROENTGEN EXAMINATION. Stereo roentgeno-

grams were obtained three days after primary

lip closure and five times thereafter (Figure

2).

STEREOMETRIC CALCULATIONS. The stability

of the implants was checked at each exami-

nation by calculating the distance between

either of the two implants in each segment

and comparing the actual value to that of the

initial examination (Selvik, 1974, p 177). The

implant triangles represent the segments in

the calculations of movement which is ex-

pressed in terms of rotations about and trans-

lations along the cardinal axes of the head

(Figure 3). The calculated rotation angles are

valid for the entire bone segment provided no

deformity of the bone takes place. The cal-

culated translations refer to the center of grav-

ity of the implant triangles in each segment.

In the present study, movement of the right

(cleft) segment was calculated relative to the

left (non-cleft) segment which was regarded

as fixed. Additionally, the translations of each

individual implant in the right segment were

secondary

repair

x

lip

A-Aq

Tome... first primary

molars

T T

18

i

I

o-

111

1 C IC

24 42 age (months)

roentgen

examinations

1

Y M

FIGURE 2. Changes in intra-oral transverse dimensions measured on casts and given in relation to age. Surgery,

oral orthopedic treatment, and roentgen examinations (I-VI) are indicated. T-Ti: intertuberosity width, A-A;1:

intercanine width (Hellquist and Skoog, 1976).

Rune, et al., ORAL ORTHOPEDICS STUDIED BY ROENTGEN STEREOMETRY

calculated relative to the implant triangle in

the left segment. Rotations larger than 1.2

degrees, translations larger than 0.4 mm, and

distance changes larger than 0.3 mm were

Z

FIGURE 3. Directions of the cardinal axes aboutand along which rotations and translations are calculatedfor the skeletal segments. Positive directions of the rota-tions are indicated.

387

considered significant, as determined from

tests of the accuracy of the method (Rune et

al., 1979). For a detailed account of the radio-

graphic and kinematic principles see Selvik

(1974).

MrasurEmENTs oN casts. An alginate

impression was taken of the maxilla at the

time of each roentgen examination, and an

additional impression was taken during the

expansion treatment period. Transverse di-

mensions (Hellquist and Skoog, 1976) were

measured on the casts, and changes were

noted (Figure 2). Additionally, the change in

distance was noted between the lingual cusps

of the first primary molars from the beginning

of their eruption at the age of 17 months.

Results

Imprant sramBILTy. The three implants in

the left segment remained stable in the bone

for 1084 days (Table 1). In the right segment,

the distance between two anterior implants

(A, Figure 1) changed by 0.6 mm during the

interval between roentgen examinations I and

II. (In the right segment, two anterior im-

plants, 4, and one implant located in the

palate, P, constituted the implant triangle

while an unstable lateral implant, L, was

TABLE 1. Implant stability (mm) calculated for three implants in the right (cleft) and three implants in the left

(non-cleft) maxillary segment. The figures indicate the total amount of displacement of the three implants within

each bone segment measured from their positions at the initial examination. Examination numbers according to

indications in Figure 2.

Examination

Days after Right LeftInitial Examination Number Segment Segment

398 ' II .349 096515 III .669 105525 IV 114 A114722 V 202 .0981084 VI 172 110

TABLE 2. Movement of right (cleft) segment relative to left (non-cleft) segment given as rotations about andtranslations along the body-fixed cardinal axes (X-, Y-, and Z- axes) with positive direction of rotations asindicated in Figure 3. The data for rotation and translation all refer to changes from exammatlon time I.

Examination numbers according to indications in Flgure 2.

Rotation about (degrees) Translation along (mm)

_ Days after _ Examination

First Examination Number X-axis Y-axis Z-axis X-axis Y-axis Z-axis

398 II -1.6 -3.0 12.1 -O0.9 -1,5 1.0515 III 1.5 -4.5 22.2 -2,.4 -1,.2 0.9525 IV -2.3 -3.6 6.2 -1.5 -O," 0.7722 V -3.0 -3.9 10.8 -O," -1.6 1.0

1084 VI 3.1 -5.6 31.1 . -0.4 -2.8 1.2

388 Cleft Palate Journal, October 1979, Vol. 16 No. 4

disregarded). During intervals II to III and

III to IV, the distance 4-4 in the right seg-

ment changed by 0.9 and -1.4 mm respec-

tively, with one implant A4 moving laterally-

caudally (II to III) and medially-cranially (IIl

to IV). During interval V to VI the distance

A-A changed by 1.0 mm (one implant 4

moving caudally-distally). The total change

in distance 4-4 was 1.3 mm in 1084 days (I to

VI).

Right

10 mm{

10 mm <

10 mm-<

MovEMENT RECORDED BY ROENTGEN STER-

EomMETrRY. Movement of the right (cleft) seg-

ment calculated relative to the left (non-cleft)

segment was modest except for rotations

about the sagittal (Z-) axis (Table 2, Figure

4). In the 398 days following primary lip

closure (I to II), the cleft segment rotated with

the lateral alveolar ridge turning medially

(positive direction about the Z-axis); and it

was translated laterally, caudally, and ante-

Left

---------

Left

FIGURE 4. Computed move-

ment between implant triangles

projected on the frontal (XY), the

sagittal (ZY), and the transverse

(XZ) plane. The changes are given

in relation to the positions in the

coordinate system of the initial ex-

amination. Outlines of the segments

are drawn schematically. The figure

does not represent movement of the

alveolar areas and the dental arch.

The numbers refer to roentgen ex-

aminations indicated in Figure 2.

Rune, et al., ORAL ORTHOPEDICS STUDIED BY ROENTGEN STEREOMETRY

riorly (along the X-, Y-, and Z- axes). During

117 days when expansion treatment was oc-

curring (II to III), the segment rotated with

the lateral alveolar ridge turning further me-

dially (about the Z-axis); and it was translated

further laterally by 1.5 mm.

In the ten days after primary palate repair

(III to IV), the segment rotated with the

anterior part turningcranially (negative di-

rection about the X-axis) and the lateral al-

veolar ridge turning laterally (negative direc-tion about the Z-axis); and it was translatedmedially.

During the following 559 days (IV to Vand V to VI), the segment rotated with thelateral alveolar ridge turning medially (aboutthe Z-axis); and it was translated mediallyand caudally.

MEasurEs on casts. After primary lip clo-sure, a small decrease in the intercanine dis-tance occurred while the intertuberosity dis-tance remained unchanged (Figure 2). Duringexpansion, all measured distances increased.After primary palate repair, when oral or-thopedic treatment was terminated, a contin-uous narrowing of the dental arch occurred.The intertuberosity distance was stabilizedfrom ten days and the intercanine distancefrom 107 days after primary palate repair,while the distance between the first primarymolars decreased during the entire remamlngobservation period.

Discussion

ImpLANT staABILITY. In the right segment, atotal change of 1.3 mm was considered ac-ceptable between two implants measuring 1.5X 0.5 mm during an observation period of

almost three years (1084 days). Certain insta-bility should be expected during a period ofsettling-in after insertion (Aronson, 1976;Rune et al., 1977 a; Rune et al., 1979). Themeasured changes between implants 4-4 inthe right segment during intervals II to IIIand III to IV may have been caused by elasticdeformity of the bone, however, as a result ofthe expansion treatment. Movement of im-plant 4 during interval V to VI followed thegeneral direction of tooth eruption.

__ MovEmMENT RECORDED BY ROENTGEN STER-, EOMETRY. The predominant movement of theright (cleft) segment was a continuous rota-tion about the sagittal (Z-) axis with thelateral alveolar ridge turning medially. The

389

- direction of this rotation was reversed onlyduring a short period after primary palaterepair. After this procedure, even a smalltranslation laterally of the cleft segment wasreversed into a continuous translation medi-ally. Thus, movement of the cleft segmentseemed to be influenced by palatal surgery,while no effect was observed from secondary:lip repair. Orthopedic expansion treatmentprior to primary palate repair had little influ-ence on the position of the cleft segment. Itresulted only in a limited translation laterally,and this relapsed completely within sevenmonths. Generally, the movements of the cleftsegment followed a developmental pattern ofrotations about the Z- and Y- axes as previ-ously observed after primary palate repair infive UCLP patients who had had no oralorthopedic treatment (Rune et al., 1979).Mrasures on casts. A continuous decrease

of the intercanine distance after primary lipclosure (I to II) corresponded with the ob-served rotation of the cleft segment about theZ-axis (with the lateral alveolar ridge turningmedially), while it contrasted with the rota-tion about the Y-axis (with the anterior part -of the segment turning laterally). The increasein intra-oral transverse distances during ex-pansion treatment was consistent with thelimited translation laterally of the bone seg-ment, while it contrasted with the directionof the rotation of the cleft segment about theZ-axis (with the lateral alveolar ridge turningmedially). Thus, changes brought about bythe orthopedic appliance appeared to havebeen restricted mainly to movements of teethand adaptation of supporting alveolar bone.Appliance-related changes in positions ofmaxillary bone segments appeared to be min- |imal. Immediately after primary palate re-pair, when expansion treatment was discon-tinued, all transverse intra-oral dimensionsdecreased while, at the same time, the cleftsegment rotated (about the Z-axis) with thelateral alveolar ridge turning laterally. Againintra-oral changes differed from the rotationaldirections of the bone segment movement.This was the case even after secondary liprepair when the intercanine and the intertu-berosity distance remained unchanged, whilethe cleft segment continued its rotation (aboutthe Z-axis) with the lateral alveolar ridgeturning medially. The intro-oral changes ob-served after primary palate repair (IV to VI) -

390 Cleft Palate Journal, October 1979, Vol. 16 No. 4

-were similar to changes which Robertson and

Fish (1975) declared "consistent with the con-

cept of rotation of the maxillary fragments

about axes in the molar or retromolar areas,

together with growth of the arches." In our

patient, however, a small rotation about the

Y-axis occurred during this period with the

anterior part of the segment turning laterally.

Thus, rotational movements of the cleft

segment occurred mainly in opposite direc-

tions to the changes measured on casts, a

finding which seems paradoxical since the

casts are models of the oral parts of the seg-

ments. We have no explanation for these dif-

ferences. It may be stressed, however, that the

recorded segmental movements occur through

growth changes and/or deformity in the cir-

cum-maxillary sutures, while the measured

intra-oral dimensions change by appositional

growth and remodelling as well. In our pa-

tient the bone segment seemed to move ac-

cording to a certain developmental pattern,

while the changes in the alveolar areas and

the dental arch could be regarded as compen-

satory. The maxillary bones and the alveolar

areas did not move "as one unit" at any time,

and movement of the maxillary bone seg-

ments could not be verified from transverse

measurements on casts. Treatment effects on

alveolar bone and dental arch dimensions

were recorded by this method, however.

Taken together, the two methods of monitor-

ing change gave more information than either

taken alone.

References

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