1-s2.0-S1073874601800657-main

Cephalometric Changes After Long-Term Early Treatment With Face Mask and Maxillary Intraoral Appliance Therapy Prinda Lertpitayakun, Kuniaki Miyajima, Ryuzo Kanomi, and Pramod K. Sinha

This article reports on a retrospective study of 25 children (mean age, 4 years 2 months) exhibiting Class III malocclusions and anterior cross-bites who were treated with a face mask and a maxillary intraoral appliance. Cepha- Iometric radiographs were taken for all treated patients at three intervals: before treatment (TO), after treatment (T1), and at posttreatment follow-up (T2). A control group consisted of 10 untreated Class III children (mean age, 3 years 11 months). Cephalometric radiographs were taken periodically for observation in this group. Paired t tests and independent t tests were performed to determine the significance of skeletal and dental changes related to treatment. Early therapy produced significant skeletal and den- toalveolar changes. The maxilla moved further forward in the treated group. Mandibular growth was similar in both treated and untreated groups. There was an improvement in the maxillomandibular relationship in the treated group. This was because of the proclination of the maxillary incisors and the retroclination of the mandibular incisors. Self-correction of the original anterior cross-bite in the untreated group occurred. Long-term follow-up re- vealed a decrease in overjet mainly caused by the proclination of the mandibular incisors. However, positive overjet was maintained throughout the study period. Despite some relapse, the treated group showed a net positive improvement in occlusion. (Semin Orthod 2001;7:169-179.) Copyright © 2001 by W,B. Saunders Company

T he te rm early treatment simply means orthodontic therapy under taken during the

most active stages of denti t ion and craniofacial skeletal growth. J o o n d e p h 1 stated that "the ob- jective of early or thodont ic t rea tment is to create a more favorable envi ronment for future deuto- facial development . Interceptive t rea tment can

From private practice, Bangkok, Thailand; Department of Orth- odontics, St. Louis University, Center for Advanced Dental Ed- ucation, St. Louis, MO; private practice, Himeji City, Hyogo-ken, Japan.

Address correspondence to Kuniaki Miyajima, DD& M£, PhD, Department of Orthodontics, St. Louis Univen~ity, Center for Ad- vanced Dental Education, 3320 Rutger Street, St. Louis, MO, 63104.

Copyright © 2001 by W.B. Saunders Company 1073-8746/01/0703-0004~35.00/0 doi: l O. 1053/sodo. 2001.26691

reduce the amoun t of dental compensat ions to skeletal discrepancy that are often associated with a more severe malocclusion in late adoles- cence."

The goals of early interceptive t rea tment may include: 1,2

1. Prevent progressive, irreversible soft-tissue or bony changes;

2. Reduce skeletal discrepancies and provide a more favorable env i ronment for normal growth;

3. Improve occlusal function; 4. Enhance and possibly shorten phase II com-

prehensive treatment; and 5. Provide a more pleasing facial esthetic, po-

tentially improving the psychosocial develop- men t of the child.

Seminars in Orthodontics, Vol 7, No 3 (SeptEmber), 2001: pp 169-179 169

170 Lertpitayakun et al

SusamP studied 409 cephalograms of Japa- nese patients with anter ior cross-bites. He found that maxillary growth retardat ion in the deciduous and early mixed denti t ion tended to con- tinue into adulthood, and the relatively exces- sive growth of the mandible increased until the end of growth. Clinical studies have used maxillary protract ion in the late-mixed to early-perma- nen t dentit ion stages of deve lopment to take m a x i m u m advantage of growth. If the opportu- nity exists, t rea tment should begin in the deciduous dentition, after the child is 5 years of age, but it also has a significant or thopedic effect in the mixed dentition. 4-6 According to da Silva Filho et al, 7 f rom the p e r m a n e n t denti t ion stage on, its effect is essentially limited to dentoal- veolar changes. Cozzani 8 stated that t rea tment should be started as early as 4 years of age. The extraoral traction that pulls the maxilla forward functions in the same general direction as the direction of deve lopment and thus appears to have a bet ter chance of remaining stable.

There are multiple factors that affect the results of face mask therapy. The differing effects of traction of the maxilla depend on the direction and point of force application. 9 Age of the pat ient and durat ion of application of traction also play a role. 1° There have been several studies on the effect of maxillary protract ion appliances in the t rea tment of anter ior cross-bite both clinically and experimentally. The following t rea tment results have been repor ted and agreed on by many investigators:

1. Maxillary anter ior displacement, 4,7,H-29 2. Counterclockwise rotation of the maxilla, 4,7,17,24,28 3. Mandibular backward and downward rota-

tion,4,7.15-20,22 26,28

4. I m p r o v e m e n t in facial profi le , 7,11-12,15,17,24-25 5. Proclination of the maxillary i nc i so r s , 7,17,22,25-26,28

6. Ret roc l ina t ion of the m a n d i b u l a r inci- so r s~ 7'17'19'23'25'26 and

7. Increase in vertical dimension. 7,1~,16-~8,22,25

Long-term stability of protract ion therapy has been reported. Williams et a122 observed 28 growing children pos t t rea tment with rapid palatal expansion (RPE) and maxillary protraction. The anter ior c o m p o n e n t of m ovem en t of the maxilla resulting f rom t rea tment was stable during the per iod of observation, and, in fact, the maxilla cont inued to move anteriorly after treatment . This may be at tr ibuted to normal growth

after t reatment. The maxillary incisors showed fur ther proclination. The positive overjet and overbite were maintained. The effects of maxillary protract ion appear to be stable.

After active protract ion of the maxilla with a face mask, relapse was repor ted by a few investigators. In a study by Gallagher et al, 19 the maxilla relapsed by rotating clockwise, negat ing some of the t rea tment results. The mandible resumed a normal growth direction (downward and forward), and the mandibula r incisors flared more than normal.

Relapse in the overjet corrected by reverse headgear t rea tment appeared to be caused by a combinat ion of pos t t rea tment forward growth of the mandible and proclinat ion of lower incisors compared with the clockwise rotation of the mandible and retroclination of the lower incisors observed at the end of active treatment. :~°

Because of the variability in facial growth, accurate individualized growth predict ion is not possible. Ngan et aP ~ found that t rea tment results were stable 2 years after removal of the appliances. At the end of a 4-year pos t t rea tment observation period, 15 of the 20 patients maintained a positive oveljet or an end-to-end incisal relationship. Patients who reverted to a negative overjet were found to have excess horizontal mandibula r growth that was not compensa ted by proclinat ion of the maxillary incisors. Overcor- rection of the overjet and molar relationship was r e c o m m e n d e d to anticipate subsequent horizontal mandibula r growth. Petit -~2 suggested the Frankel III regulator be used for 6 months after protract ion therapy.

Purpose of the Study

A n u m b e r of clinical studies have been per- fo rmed document ing the initial and short-term response to maxillary expansion and protraction. Data on the long-term effects of maxillary protract ion, and the longitudinal data on un- t reated patients with Class III malocclusions and anter ior cross-bites are limited with regard to sample size and durat ion of longitudinal record keeping. Most studies featured few patients and short observation intervals. The purpose of this study was to evaluate the long-term changes of face mask therapy combined with a maxillary intraoral appliance in the correct ion of Class III malocclusions in a sample of Japanese patients

Maxillary Protraction 171

in the pr imary dent i t ion and c o m p a r e the findings with an un t r ea t ed Class III sample. This retrospective study fol lowed-up pat ients front pr imary dent i t ion to p e r m a n e n t dent i t ion.

Materials and Methods

Patients

The t reatment g roup consisted o f pretreatment , posttreatment, and retention lateral cephalograms of 25 Japanese children with Class III malocclusions and anterior cross-bites who were treated with protract ion headgear and a maxillary intraoral appliance in the office o f Dr. Kanomi. Ten boys and 15 girls were selected with the mean age at the start of t reatment o f 4 years 2 months (range, 2 years 11 months to 6 years 1 month) . The average t rea tment time was 16.12 months. None of the patients had a history o f craniofacial anomalies or had unde rgone prior o r thodont ic treatment.

The cont ro l sample consisted o f 10 un t r ea t ed Japanese chi ldren with Class III malocclus ions and an te r ior cross-bites. Six boys' and fou r girls' records were retr ieved f rom the same private pract ice and were m a t c h e d for age as best as possible with the exper imenta l group. The m e a n age at the start o f observat ion was 3 years 11 mon ths with an age range o f 2 years 7 m o n t h s to 5 years 5 months. Cephalometr ic iadiographs were taken periodically for observation (Table 1).

Appliance Design for Treatment Group

The maxillary intraoral removable appl iance consisted o f an acrylic pos ter ior bite plate with Adam ' s clasps, labial bow, and two l ingual springs act ing on the maxillary incisors. Two hooks were placed between the dec iduous canines and first dec iduous molars for engag ing elastics to the face mask (Figs 1 and 2). T h e face mask is shown in Figures 3 and 4. Approx imate ly

Figure 1. Maxilla17 intraoral appliance.

250g o f p ro t rac t ion force was delivered per side to the hooks, with elastics adjusted to effect a downward and forward pull at 30 ° to the occlusal plane. The lingual springs were activated periodically du r ing t reatment . The pat ients were in- s t ructed to wear the face mask 10 hours pe r day and were t rea ted until a positive overjet had b e e n attained. After the t r ea tmen t was com- pleted, the maxil lary intraoral removable appliance was used as a retainer. The patients wore the removable re ta iner du r ing sleep for 1 year.

Cephalometric Analysis

Cepha lomet r i c rad iographs were taken for all t rea ted pat ients at three intervals: before treat- m e n t (TO), after t r ea tmen t (T1), and at follow-up (T2). In the cont ro l sample, serial lateral cepha lomet r i c rad iographs were col lected to ma tch t ime as accurately as possible, corre- spond ing to the t r ea tmen t and pos t t r ea tmen t per iods o f the t reated group. T h e cepha lomet r i c rad iographs were taken in centr ic occlus ion with the same cephalostat .

Table 1. Mean Ages of the Treated and the Untreated Control Groups

Treated Group Untreated Control (N= 25) (N= 10)

TO 4 yr 2 mo 3 yr 9 mo T1 5 y r 6 m o 7yr 10mo T2 13 yr 1 mo 11 yr 9 mo T0-TI 1 yr 4 mo 4 yr 1 lno T1-T2 7 yr 7 mo 3 yr 11 mo T0-T2 8 yr 11 mo 8 yr Figure 2. Elastics engaging the hooks between decidu-

ous canines and first deciduous molars to the face mask.


Figure 3. Frontal view of a patient wearing the face mask appliance.

M1 lateral cephalometric radiographs were manually traced on tracing film with a mechanical pencil and 0.03-ram lead. Digitization for cephalometric analysis was performed with the Dentofacial Planner software 7.0 program (Dentofacial Soft- ware Inc., Toronto, Ontario, Canada) on each landmark of all tracings. Skeletal and dental measurements were obtained from the computer dig- itizing program. Thirty angular and linear skeletal and dental measurements were used in this study.

Method Error

The reproducibil i ty of the measurements was evaluated by statistically analyzing the difference between double measurements made at least 1 mon th apart of 10 randomly selected patients. The cephalograms were retraced and redigi- tized. The error of the me thod was calculated with Dahlberg 's formula:~:

Sx

where d is the difference between the repeated measurements and n is the n u m b e r of double measurements made. The er ror for angular and linear measurements on the eephalometr ic radiographs did not exceed 0.60 ° and 0.34 mm, respectively.

Statistical Analyses

Paired t tests (P < .05) were pe r fo rmed to compare skeletal and dental changes within groups. I n d e p e n d e n t t tests (P < .05) were used to compare skeletal and dental changes between groups.

Results

At T1, 50% of the unt rea ted patients (5 of 10 patients) exhibited a self-correction of the original anter ior cross-bite. Cross-bite was obsmwed in two of the remaining five patients, and three exhibited an edge to edge incisor relationship.

At T2, 9 of the 10 unt rea ted patients showed positive oveljet by self-correction and 1 presented with an edge to edge incisor relationship.

At T0, the maxi l lomandibular sagittal relationship, as indicated by the ANB angle, Wits, and overjet, tended more toward a skeletal Class III pat tern in the t reated group than in the untreated control g roup (Table 2).

At T1, the control g roup showed significant proclinat ion of both maxillary and mandibular anter ior teeth as presented by U1 to SN (P < .05), incisal mandibular plane angle (IMPA) (P < .001), L1 to A-Pog (P < .001), and U1 to L1 (P < .001) (Table 3).

At T2, no significant differences were seen between the treated and untreated groups. How- ever, maxillary and mandibular lengths as indicated by ptm-pt A and Co-Gn were significantly larger in the t reated patients than in the untreated ones. The y axis (FH/S-Gn) tended to open more in the untreated group (64.02 ° v 61.40 °, at P < .05) (Table 4).

The cephalometric changes from TO to T1 (Ta- ble 5) showed a significant increase in SNA, ANB, and Wits (functional) in the treated group compared with the control (SNA, 1.07 v -0.96, P < .01; ANB, 1.95 v -0.25, P < .001; Wits, 3.05 v

Figure 4. Side view of a patient wearing the face mask appliance. Approximately 250g of protraction fbrce delivered per side with a downward and forward pull at 30 ° to the occlusal plane.

Maxillary Protraction 1 7 3

Table 2. Pretreatment (TO) Cephalometric Comparison Between the Treated Group and the Untreated Control Group

Treated (n = 25) Control (n = 10)

Variable Mean SD Mean SD T Value P Value Sign

Maxillary skeletal SNA 80.12 4.28 82.12 3,91 1.28 .2108 NS Co-pt A (mm) 73.88 3.30 73.19 3.51 -0.55 .5890 NS ptm-pt A (mm) 41.02 2.36 40.84 2.44 -0.21 .8379 NS

Maxillary dental U1-SN 88.80 7.19 85.54 4.02 -1.35 .1876 NS

Mandibular skeletal SNB 80.30 3.83 79.78 2.40 -0.39 .6959 NS SNPog 79.61 3.71 79.34 2.21 -0.21 .8329 NS Y-axis (FH/S-Gn) 60.74 2.8l 61.46 2.52 0.70 .4871 NS Co-Gn (ram) 94.34 4.22 91.95 3.65 -1.57 .1256 NS

Mandibular dental IMPA 79.88 6.00 81.87 4.26 0.96 .3465 NS L1 to A-Pog 2.94 1.41 2.12 1.36 -1.57 .1253 NS

Maxillomandibular relationship ANB -0.17 1.73 2.35 2.96 2.52 .0275 * Wits appraisal (mm) -5.53 2.23 -3.75 1.30 2.36 .0246 * Wits functional (mm) -6.15 2.40 -4.04 1.32 2.61 .0135 * U1-L1 157.27 11.22 157.88 6.88 0.16 .8738 NS Overjet (mm) -2.67 1.02 -1.70 0.93 2.59 .0143 * Overbite (ram) 1.89 1.77 0.67 0.94 -2.05 .0483 *

Vertical relationship Occlusal plane angle (SN-OP) 18.87 3.18 19.34 3.63 0.38 .7052 NS Occlusal plane angle (SN-Function OP) 20.04 3.77 19.91 2.74 -0.10 .9219 NS Palatal plane angle (SN/ANS-PNS) 6.65 3,50 6.39 1,40 -0.32 .7543 NS Mandibular plane angle (SN-GoMe) 34.58 3.98 35.41 3.48 0.58 .5685 NS Gonial angle (Ar-Go-Gn) 127.72 6.33 128.21 3.80 0.23 .8227 NS UAFH (N-ANS) (mm) 43.29 2.98 42.52 2.17 -0.74 .4638 NS LAFH (ANS-Me) (ram) 56.98 3.88 56.85 2.79 -0.10 .9216 NS AFH (N-Me) (ram) 99.31 5.63 97.81 3.63 -0.78 .4421 NS PFH (S-Go) (ram) 64.86 3.27 63.20 2.32 -1.46 .1544 NS PFH/AFH (%) 64.40 3.27 64,26 2.47 -0.12 .9067 NS

Soft tissue Nasolabial angle 97.04 10.18 102.94 12.72 1,44 .1590 NS Upper lip to E plane 0.97 1.42 1.10 1.87 0.22 .8272 NS Lower lip to E plane 2.88 1.95 2.00 1.61 -1.27 .2146 NS Cant of upper lip 21.90 7.03 17.77 9.24 -1.44 .1604 NS

*P < .05. Abbreviation: NS, not specified.

- 0 .48 , P < .001). Maxillary length was significantly

less in the t reated g roup as d e t e r m i n e d by variable

Co-pt A (3.16 m m v 7.9 mm, P < .001) as was

mandibu la r length (Co-Gn, 3.10 m m v 13.49 mm,

P < .001). Moreover , maxillary and mand ibu la r

dental measurements (U1-SN, IMPA, L1 to A-Pog,

and U1-L1) showed that the control g roup had a

greater tendency of procl ina t ion o f incisors than

did the t reated patients. I m p r o v e m e n t of soft-tis-

sue profi le was shown in the t reated g roup com-

pared with the un t rea ted patients. No significant

changes occur red in the occlusal p lane and palatal

plane angles between the two groups but the man-

dibular plane angle appea red to have increased in

the un t rea ted control.

Af ter l ong- t e rm follow-up f r o m T1 to T2 (Ta-

ble 6), the changes be tween the t rea ted and

u n t r e a t e d g roups showed no s ignif icant increase

in SNA, SNB, ANB angles, and Wits. An increase

in maxi l lary a n d m a n d i b u l a r l eng ths was ob-

served in the t r ea ted g r o u p c o m p a r e d with the

u n t r e a t e d g roup . T h e r e was also an increase in

p roc l ina t i on o f maxi l lary and m a n d i b u l a r inci-

sors in the t r ea ted g roup . T h e r e was a s ignif icant

increase in the palatal p lane angle in the t rea ted

g r o u p w h e n c o m p a r e d with the u n t r e a t e d g r o u p

(1.80 v - 0 . 2 9 , P = .047).

Discussion

Many previous studies r e g a r d i n g the co r r ec t i on

o f Class III malocc lus ions with face mask therapy


Tab le 3. Post t reatment (T1) Cephalomet r ic Compar ison Between the Trea ted Group and the Unt rea ted Control Group


Variable Mean SD Mean SD T Value P Value Sign

Maxillary skeletal SNA 81.19 3.50 81.16 3.74 -0.02 .9810 NS Co-pt A (mm) 77.03 3.48 81.09 4.13 2.95 .0057 ** ptm-pt A (mm) 42.59 2.12 44.24 2.75 1.91 .0649 NS

Maxillary dental U1-SN 98.80 7 .81 106.61 8.59 2.60 .0139 *

Mandibular skeletal SNB 79.40 2.84 79.07 2.55 -0.32 .7544 NS SNPog 79.08 2.68 78.93 2.73 -0.15 .8796 NS Y-axis (FH/S-Gn) 61.55 2.40 63.45 3.20 1.92 .0629 NS Co-Gn (ram) 97.45 5.03 105.44 3.92 4.49 <.0001 ***

Mandibular dental IMPA 77.94 8.42 89.30 3.11 5.83 <.0001 *** L1 to A-Pog 0.93 2.05 3.85 1.44 4.09 .0003 ***

Maxillomandibular relationship ANB 1.78 1.67 2.10 3.18 0.31 .7655 NS Wits appraisal (ram) -2.49 1.65 -2.42 2.64 0.10 .9228 NS Wits functional (mm) -3.10 2.41 -4.52 3.10 -1.45 .1574 NS U1-L1 149.24 15.69 128.03 8.95 -4.00 .0003 *** Oveljet (ram) 2.50 0.89 2.20 2.60 -0.36 .7284 NS Overbite (mm) 1.61 1.37 1.66 1.81 0.09 .9323 NS

Vertical relationship Occlusal plane angle (SN-OP) 17.11 3.06 17.45 4.32 0.26 .7951 NS Occlusal plane angle (SN-Function OP) 17.99 3.27 20.46 4.24 1.85 .0726 NS Palatal plane angle (SN/ANS-PNS) 6.62 2.98 8.11 1.89 1.46 .1526 NS Mandibular plane angle (SN-GoMe) 34.65 3.98 37.24 4.17 1.72 .0955 NS Gonial angle (Ar-Go-Gn) 125.58 6.84 126.41 3.67 0.36 .7214 NS UAFH (N-ANS) (mm) 44.95 2.95 50.27 3.02 4.79 <.0001 *** LAFH (ANS-Me) (ram) 59.84 4.78 73.54 4.61 2.09 .0444 * AFH (N-Me) (ram) 103.46 6.10 112.38 6.51 3.84 .0005 *** PFH (S-Go) (mm) 67.46 3.85 71.07 2.85 2.68 .0115 * PFH/AFH (%) 64.56 3.15 63.88 2.88 -0.59 .5616 NS

Soft tissue Nasolabial angle 104.83 10.51 97.34 12.51 - 1.81 .0801 NS Upper lip to E plane 1.76 1.69 1.73 2.06 -0.05 .9600 NS Lower lip to E plane 2.25 2.03 2.96 2.23 0.91 .3689 NS Cant of upper lip 16.88 6.98 18.38 7.55 0.56 .5771 NS

*P < .05. **P < .01. ***P < .001. Abbreviation: NS, not specified.

h a v e n o t i n c l u d e d a c o n t r o l g r o u p o r Class I

pa t i en t s . T h e l ack o f d a t a is p r o b a b l y o w i n g to

t h e low p r e v a l e n c e o f th is type o f m a l o c c l u s i o n ,

a n d t h e e t h i c a l q u e s t i o n o f t r e a t i n g t h e p r o b l e m

w h e n i t exists. F o r t u n a t e l y , u n t r e a t e d Class I I I

s a m p l e s w e r e ava i l ab le f o r use in this s tudy as a

c o n t r o l g r o u p . I n a r e t r o s p e c t i v e s tudy, i t is al-

m o s t i m p o s s i b l e to a s s e m b l e idea l ly m a t c h e d

g r o u p s . C h i l d r e n in t h e c o n t r o l g r o u p t e n d to

e x h i b i t m i l d e r i n c i s o r m a l o c c l u s i o n wi th a

g r e a t e r d e g r e e o f d e n t o a l v e o l a r c o m p e n s a t i o n

a n d m a n y d o n o t wish to w e a r a p p l i a n c e s . Chi l -

d r e n in t h e t r e a t e d g r o u p s , by d e f i n i t i o n , h a d a c l ea r t h e r a p e u t i c n e e d . 34 A g e s a t e a c h s tage in

T a b l e 1 s h o w e d s l ight ly d i f f e r e n t t imes w h e n

c e p h a l o m e t r i c r a d i o g r a p h s w e r e t a k e n f o r b o t h

g r o u p s . T h e r e a d e r s h o u l d k e e p in m i n d t h a t

g r o w t h p l a y e d an i m p o r t a n t r o l e in t h e i n t e r p r e -

t a t i o n o f this s tudy.

A t p r e t r e a t m e n t (TO), t h e sever i ty o f Class I I I

m a l o c c l u s i o n s as i n d i c a t e d by A N B , Wits, a n d

o v e r j e t va r i ab le s was s ign i f i can t ly less in t h e un -

t r e a t e d c o n t r o l g r o u p .

A f t e r t h e r a p y , t h e resu l t s s h o w e d t h a t t rea t -

m e n t i n d u c e d s i g n i f i c a n t ske le ta l a n d d e n t o a l v e -

o l a r c h a n g e s . T h e m a x i l l a m o v e d f o r w a r d (1.07 °

i n c r e a s e in S N A a n d 1.95 ° in A N B ) . A n i n c r e a s e

in t h e m a x i l l a r y i n c i s o r i n c l i n a t i o n a n d t h e cor-

Maxillary Protraction 175

Table 4. Post-Follow-up (T2) Cephalometric Comparison Between the Treated Group and the Untreated Control Group


Variable Mean SD Mean SD 7" Value P Value Sign

Maxillary skeletal SNA 81.51 2.61 82.32 2,97 0.80 .4295 NS Co-pt A (mm) 89.96 5.54 87,16 2.76 -1.98 .0562 NS ptm-pt A (ram) 49.32 3.27 47.43 1.69 -2.24 ,0328 *

Maxillal y dental U1-SN 110.22 6.11 111.05 3.27 0.41 .6869 NS

Mandibular skeletal SNB 80.67 3.13 80.48 2.52 -0.17 ,8669 NS SNPog 81.44 3.04 80,71 2.95 -0.64 .5250 NS Y-axis (FH/S-Gn) 61.40 2.89 64.02 2.61 2.49 .0179 * Co-Gn (ram) 120.14 7 .66 115.88 3.93 -2.16 .0387 *

Mandibular dental IMPA 91.24 6.50 89.75 5.63 -0.64 .5290 NS L1 to A-Pog 3.74 2.34 4.50 2.48 0.85 .3998 NS

Maxillomandibular relationship ANB 0.82 2.32 1.84 2.78 1.11 .2764 NS Wits appraisal (ram) -3.22 3.01 -3.22 1.62 0.00 .9969 NS Wits functional (mm) -5.31 3.39 -4.43 2.17 0,76 .4537 NS U1-L1 126,19 8.06 123.95 8.76 -0.72 .4738 NS Oveijet (mm) 3.14 1.09 3.21 1.48 0.15 .8851 NS Overbite (ram) 2.42 1.31 2.00 1.51 -0.81 .4218 NS

Vertical relationship Occlusal plane angle (SN-OP) 15.08 3.78 16.50 3.85 1.00 .3234 NS Occlusal plane angle (SN-Function OP) 17.84 3.75 18.22 4,06 0.26 .7928 NS Palatal plane angle (SN/ANS-PNS) 8.42 3.06 7.82 1,87 -0.57 .5718 NS Mandibular plane angle (SN-GoMe) 33.49 4.87 36.41 4.24 1.66 .1069 NS Gonial angle (Ar-Go-Gn) 120.75 7.54 125.12 4.18 1.72 .0946 NS UAFH (N-ANS) (mm) 56.96 4.15 55.14 2.30 -1.30 .2027 NS LAFH (ANS-Me) (ram) 69.48 6.46 68.59 3.30 -0.53 ,5975 NS AFH (N-Me) (mm) 125.45 8 .74 122.32 3.45 -1.52 .1384 NS PFH (S-Go) (ram) 83,76 7,01 78.94 4.21 2.02 ,0513 NS PFH/AFH (%) 67,05 3,88 65.10 3.07 -1.42 .1650 NS

Soft tissue Nasolabial angle 97.56 8.78 96.76 9.24 -0.24 .8127 NS Upper lip to E plane 0.22 1.86 0.60 2.66 0,48 ,6332 NS Lower lip to E plane 1.85 1.96 2,37 3.80 0.41 .6901 NS Cant of upper lip 18.27 6.91 17.21 6,76 -0.41 .6823 NS

*P < .05. Abbreviation: NS, not specified.

r ec t ion o f the an t e r i o r cross-bite in the t r ea ted

g r o u p were caused by act ivated l ingual springs o f

the r emovab le appl iance . All pa t ien ts exh ib i t ed

posit ive overjet . Even t h o u g h t he r e was no sig-

n i f icant d i f fe rence w h e n c o m p a r e d with the un-

t r ea ted cont ro l , the t r e a t m e n t was c o n s i d e r e d

successful w h e n c o m p a r e d with the or ig ina l se-

verity. In addi t ion , the e r u p t i o n o f maxi l lary

incisors associated with an increase in labial in-

c l ina t ion may have c o n t r i b u t e d to the c o r r e c t i o n

o f the an t e r i o r cross-bite. In a study o f J a p a n e s e

ch i ld ren , Susami 3 r e p o r t e d that pa t ien ts with

an t e r i o r cross-bite showed m o r e labial incl ina-

t ion o f maxi l lary incisors than d id pat ients with

n o r m a l occlusion. Miyaj ima et a135 s tud ied the

craniofacia l g rowth in the u n t r e a t e d Class III

J a p a n e s e girls with a n t e r i o r cross-bite. T h e y

f o u n d tha t the maxi l lary incisors were t ipped

labially and the m a n d i b u l a r incisors were t ipped

l ingual ly d u r i n g d e v e l o p m e n t . This t endency be-

came g rea t e r as the den ta l stages advanced, pre-

sumably to c o m p e n s a t e for the unde r ly ing skel-

etal d iscrepancy.

T h e r e was no s ignif icant d i f fe rence in the

m e a n c h a n g e o f the palatal p l ane angle f r o m TO

to T1 be tw een the t r ea ted a n d the u n t r e a t e d

g roups ( - 0 . 0 4 ° v 1.72°). T h e u n t r e a t e d g r o u p

e x h i b i t e d an increase in the m a n d i b u l a r angle

w h e n c o m p a r e d with the t r ea ted g r o u p (1.83 ° v

0.07 °, P = .0149). T h e clinically s ignif icant rota-

t ional effect caused by p ro t r ac t i on h e a d g e a r did

n o t o c c u r in this study. T h e effects o f g rowth

176 Lertpi tayakun et al

Tab le 5. Comparison of Cephalomet r ic Changes From Pre t rea tment (TO) to Post t reatment (TI) Between the Trea ted Group and the Unt rea ted Control Group


Variable Mean Change SD Mean Change SD T Value P Value Sign

Maxillary skeletal SNA 1.07 1.82 -0.96 1.54 3.10 .0039 ** Co-pt A (mm) 3.16 2.34 7.90 2.48 -5.32 <.0001 *** ptm-pt A (ram) 1.56 1.78 3.40 1.25 -2.97 .0055 **

Maxillary dental U1-SN 10.00 8.02 21.07 10.78 -3.34 .0021 **

Mandibular skeletal SNB -0.90 1.81 -0.71 1.70 -0.28 .7776 NS SNPog -0.52 1.85 -0.41 1.64 -0.17 .8662 NS Y-Axis (FH/S-Gn) 0.81 1.45 1.99 2.58 -1.36 .1990 NS Co-Gn (mm) 3.10 3.78 13.49 3.57 -7.46 <.0001 ***

Mandibular dental IMP.& -1.94 9.70 7.43 5.83 -2.84 .0077 ** L1 to A-Pog -2.01 1.35 1.73 0.93 -8.00 <.0001 ***

Maxillomandibular relationship ANB 1.95 0.99 -0.25 1.30 5.41 <.0001 *** Wits appraisal (mm) 3.04 1.65 1.33 2.73 1.85 .0896 NS Wits functional (ram) 3.05 2.09 -0.48 2.53 4.25 .0002 *** U1-L1 -8.03 15.57 -29.85 12.86 3.92 .0004 *** Overjet (ram) 5.17 1.50 3.90 2.89 1.32 .2141 NS Overbite (mm) -0.28 1.53 0.99 2.30 -1.91 .0655 NS

Vertical relationship Occlusal plane angle (SN-OP) -1.76 2.56 -1.89 2.93 0.13 .8941 NS Occlusal plane angle (SN-Function OP) -2.05 3.80 0.55 2.94 -1.94 .0613 NS Palatal plane angle (SN/ANS-PNS) -0.04 2.45 1.72 2.14 -1.98 .0561 NS Mandibular plane angle (SN-GoMe) 0.07 1.84 1.83 1.81 -2.57 .0149 * Gonial angle (Ar-Go-Gn) -2.14 1.96 - 1.80 3.49 -0.29 .7766 NS UAFH (N-ANS) (ram) 1.66 2.17 7.75 2.79 -6.92 <.0001 *** LAFH (ANS-Me) (ram) 2.85 2.43 6.69 2.43 -4.22 .0002 *** AFH (N-Me) (mm) 4.15 4.18 14.57 4.79 6.39 <.0001 *** PFH (S-Go) (mm) 2.60 3.03 7.87 2.46 -4.89 <.0001 *** PFH/AFH (%) 0.16 1.64 -0.38 1.63 0.88 .3856 NS

Soft tissue Nasolabial angle 7.79 12.78 -5.60 8.63 3.03 .0047 ** Upper lip to E plane 0.79 1.74 0.63 1.33 0.26 .7929 NS Lower lip to E plane -0.64 2.10 0.96 1.74 -2.12 .0417 * Cant of upper lip -5.03 7.17 0.61 5.85 -2.20 .0346 *

*P < .05. **P < .01 ***P < .001. Abbreviation: NS, not specified.

w e r e p r o b a b l y g r e a t e r t h a n t h e e f fec t s o f t h e

o r t h o p e d i c f o r c e a p p l i e d .

M e a n c h a n g e s f r o m p o s t t r e a t m e n t (T1) to

p o s t - f o l l o w - u p (T2) o f t h e t r e a t e d g r o u p w e r e

m o r e t h a n t h e u n t r e a t e d c o n t r o l b e c a u s e obse r -

v a t i o n t i m e was l o n g e r in t h e t r e a t e d g r o u p (7

years 7 m o n t h s v 3 years 9 m o n t h s ) . A c c o r d i n g l y ,

t h e r e p o r t e d c h a n g e s w e r e n o t e n t i r e l y g e n e r -

a t e d by t h e r a p y . T h e f a v o r a b l e t r e a t m e n t resu l t s ,

h o w e v e r , w e r e m a i n t a i n e d in t h e l o n g - t e r m ob-

se rva t ion . T h e i m p r o v e m e n t in t h e m a x i l l o m a n -

d i b u l a r r e l a t i o n s h i p was less s i g n i f i c a n t at t h e

t i m e o f fo l l ow-up t h a n i m m e d i a t e l y a f t e r t h e

t r e a t m e n t . T h e t r e a t m e n t e f fec t s o f i n c r e a s e d

o v e r j e t w e r e d i m i n i s h e d , m a i n l y b e c a u s e o f

p r o c l i n a t i o n o f t h e m a n d i b u l a r inc isors . S u c h

r e l a p s e has b e e n r e p o r t e d in p r e v i o u s re-

s ea rch . 9:~,-~°,-~6 I n a d d i t i o n to t h e t r a n s i t i o n f r o m

p r i m a r y d e n t i t i o n to p e r m a n e n t d e n t i t i o n , t h e

r e t r o c l i n a t i o n o f t h e m a n d i b u l a r inc i so r s d u r i n g

t r e a t m e n t was i m p o r t a n t f o r m a i n t e n a n c e o f t h e

o v e r j e t c o r r e c t i o n . A t t h e e n d o f T2, 9 0 % o f t h e

u n t r e a t e d c o n t r o l p a t i e n t s e x h i b i t e d c o r r e c t i o n

o f a n t e r i o r cross-bi tes , b u t 100% o f t h e t r e a t e d

p a t i e n t s t h a t w e r e o r i g i n a l l y m o r e s eve re in

t h e m a l o c c l u s i o n s h o w e d pos i t i ve over je t . T h e

t r e a t e d g r o u p w o u l d m o s t l ikely h a v e e n d e d t h e

l o n g - t e r m o b s e r v a t i o n wi th n e g a t i v e o v e r j e t i f

Maxil lary Protraction 177

T a b l e 6. C o m p a r i s o n o f C e p h a l o m e t r i c C h a n g e s F r o m P o s t t r e a t m e n t (T1) to P o s t - F o l l o w - u p (T2) B e t w e e n t h e T r e a t e d G r o u p a n d t h e U n t r e a t e d C o n t r o l G r o u p


Variable Mean Change SD Mean Change SD T Value P Value Sign

Maxillary skeletal SNA 0.32 2.64 1.16 1.09 - 1 . 3 4 .1899 NS Co-pt A (ram) 12.93 5.28 6.07 3.41 3.79 .0006 *** ptm-pt A (ram) 6.73 2.90 3.19 1.52 4.70 <.0001 ***

Maxillary dental U1-SN 11.41 6.92 4.44 9.56 2.41 .0217 *

Mandibular skeletal SNB 1.27 2.60 1.41 0.80 - 0 . 2 4 .8129 NS SNPog 2.35 2.41 1.78 1.16 0.94 .3521 NS Y-axis (FH/S-Gn) - 0 , 1 5 1.61 0.57 1.70 - 1 . 1 8 .2465 NS Co-Gn (mm) 22.70 7.81 10.44 7.32 4.27 .0002 ***

Mandibular dental IMPA 13.30 11.19 0.45 4.44 4.87 <.0001 *** L1 to A-Pog 2.81 2.31 0.65 1.67 2.67 .0116 *

Maxil lomandibular relationship ANB -0 .95 1.85 - 0 . 2 6 1.16 - 1 . 0 9 .2827 NS Wits appraisal (mm) - 0 . 7 3 2.79 - 0 . 8 0 2.02 0.07 .9448 NS Wits funct ional (ram) -2 .21 3.26 0.09 2.41 -2 .01 .0522 NS U1-L1 -23 .05 15.42 - 4 . 0 8 11.83 - 3 . 4 9 .0014 ** Overjet (ram) 0.64 1.25 1.01 1.55 - 0 . 7 3 .4705 NS Overbite (ram) 0.80 1.54 0.34 1.74 0.78 .4436 NS

Vertical relat ionship Occlusal plane angle (SN-OP) - 2 . 0 4 3.89 0.95 2.99 - 0 . 7 9 .4346 NS Occlusal plane angle (SN-Function OP) -0 .15 3.95 - 2 . 2 4 2.56 1.54 .1321 NS Palatal plane angle (SN/ANS-PNS) 1.80 2.96 - 0 . 2 9 1.85 2.06 .0470 * Mandibular plane angle (SN-GoMe) - 1 . 1 6 3.23 - 0 . 8 3 1.25 - 0 . 4 4 .6662 NS Gonial angle (Ar-Go-C,n) - 4 . 8 4 4.09 - 1.29 1.96 - 3 . 4 5 .0016 ** UAFH (N-ANS) (mm) 12.00 3.89 4.87 2.39 5.38 <.0001 *** EAFH (ANS-Me) (ram) 9.64 4.71 5.05 4.57 2.63 .0130 * AFH (N-Me) (ram) 21.99 7.13 9.94 6.66 4.60 <.0001 *** PFH (S-Go) (ram) 16.30 6.26 7.87 4.33 3.89 .0005 *** PFH/AFH (%) 2.50 2.89 1.22 0.90 1.98 .0562 NS

Soft tissue Nasolabial angle - 7 . 2 8 13.76 - 0 . 5 8 12.91 - 1 . 3 2 .1951 NS Upper lip to E plane - 1 . 5 4 1.94 - 1 . 1 3 2.57 - 0 . 5 2 .6067 NS Lower lip to E plane - 0 . 4 0 2.20 - 0 . 5 9 3.46 0.20 .8434 NS Cant of uppe r lip 1.40 6.42 - 1.17 8.94 0.95 .3473 NS

*P < .05. **P < .01. ***P < .001.

not for the treatment. The growth redirection of maxilla was more forward to improve the skeletal discrepancy. Despite mandibular growth in the pubertal growth spurt, the occlusion was maintained in a favorable arrangement. The findings of this study indicate that early interven- tion of Class III malocclusion with face mask and intraoral appliance therapy is beneficial.

Conclusions

This was a retrospective study of the long-term stability of face mask therapy along with maxillary intraoral appliance in patients with anterior cross-bite. The records of 25 Class III patients

were compared with those of 10 untreated patients with Class III malocclusion. Growth played an impor tant role in the interpretation of the results. The major findings follow:

1. The early correction of Class III malocclusions with maxillary protraction headgear combined with a maxillary intraoral appliance p roduced significant skeletal and den- toalveolar changes. The maxilla moved significantly far ther forward in the treated group. Mandibular growth was similar in both treated and untreated groups.

2. There was an improvement in maxillomandibular relationship after treatment. The re-


suit was caused by the maxillary proclination of the maxillary incisors and the retroclination of the mandibular incisors. This likely occurred as a result o f treatment and the transition from primary dentit ion to mixed dentition.

3. Self-correction o f the original anterior cross- bite in the untreated control group occurred. Eruption of the maxillary incisors associated with an increase in labial inclination may have contributed to the correction o f the anterior cross-bite.

4. The clinically significant rotational effect ex- pected from the treatment o f the maxilla and the mandible did not occur in this study. The individual growth potential was probably greater than the effect o f the protraction force applied with regard to the rotational effect.

5. After long-term follow-up, the changes between the treated and the untreated groups showed no significant increase in SNA, SNB, ANB, and Wits. Increased overjet was dimin- ished, mainly because o f the proclination of the mandibular incisors. Positive overjet was maintained throughout the study period. De- spite some relapse, the patients showed a net positive improvement in occlusion. Early in- tervention o f Class III malocc lus ion with face mask and maxillary intraoral therapy is beneficial.

A c k n o w l e d g m e n t

The authors wish to express their sincere gratitude to Drs. Donald J. Fergnson, Dennis M. Killiany, and Gus G. Sotiro- poulos for their valuable help and comments in preparing the article.

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