CASE REPORT

Angle Class II, Division I malocclusion treated without premolar extraction

Stephen McCullough, DDS, MS" Yukon, Okla.

The treatment of an Angle Class II, Division I malocclusion without the extraction of premolars is described. Treatment was accomplished with the standard edgewise appliance using Merrifield directional forces systems. (AM J ORTHOD DENTOFAC ORTHOP 1994;106:317-21.)

W h e n one thinks of orthodontic treat- ment that employs the "Tweed Technique," a com- mon misconception is that the t reatment requires the removal of the four first premolars. Indeed, Tweed 's t reatment of a bimaxillary protrusion case that required this diagnosis forever changed orth- odontic thought. However, since Tweed 's era, there has been a constant refinement of the Tweed philosophy and of Tweed 's t reatment techniques. Levern Merrifield's studies of directional forces ~ and dimensions of the denture 2 and the subsequent development of his sequential force systems 3 has made it possible to properly diagnose, t reatment plan, and treat any type of ma locc lu s ion -no t just the Angle Class I or Class II with crowding and protrusion.

This case report will demonstra te the use of both the Tweed-Merrifield philosophy and the Merrifield force systems to correct an Angle's Class II, Division 1 dental malocclusion that was not complicated by substantial crowding or protrusion.

DIAGNOSIS

A 12-year-01d boy presented with a full-step Angle Class II, Division 1 malocclusion. The casts (Fig. 1) exhibited an overjet of I1 mm and a deep impinging overbite. The mandibular anterior teeth were reasonably well aligned with only minor crowding, but the depth of the curve of Spee was 4 mm. By using Merrifield's total dentition space analysis, the calculations reflected an anterior denture surplus of 3 mm, a midarch deficit of 6 mm and a posterior deficit of 3 ram. The total denture deficit was 6 mm (Fig. 2).

The cephalometric tracing (Fig. 3) confirmed a Class II skeletal pattern. The ANB angle was 5 ~ The mandibu-

aClinical Associate Professor, University of Oklahoma, College of Den- tistry, Graduate Orthodontic Department. Copyright �9 1994 by the American Association of Orthodontists. 0889-5406/94/$3.00 + 0 8/4/48286

Fig. 1. Pretreatment casts.

lar plane was a relatively flat 21 ~ and the mandibular incisor was an upright 85 ~ with mandibular plane. The FMIA of 74 ~ and the Z-angle of 74 ~ were reflections of a very "straight" facial profile. The pretreatmcnt pan- clipsc (Fig. 4) exhibitcd healthy teeth and supporting structures. The facial photographs (Fig. 5) confirmed a balanced and harmonious facial appearance. On smiling, there was excessive gingival display.

317

A. Anterior denture area

a. Teeth v,,idth ~t4

b. Available space 3 2 I 1 2 3 e. Tooth arch disc - 1 d. Headfilm correction + 4

e. S o f t l ' i s s u e M o d i f i c a t i o n 0

D e | l c i t B. Mid-arch denture area

a. Teeth width b. Available space c. l b o t h arch disc d, C u ~ ' e of spee

C, Posterior denture area

a, Teeth width b. Available space c. Tooth arch disc d. Estimated increase

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FbtlA 74 ~ FHA 21" LMPA 85* SNA 81 ~ SNB 76". ANB 5* OP-FH 10 ~ A O B O 0 mm Z ANGLE 74 ~ AF~ 59 turn.

PIER 4-~ ram.

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., 40 29

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Fig. 2. Total dentition s p a c e analysis .

318 ]~lcCullough American Joun,al of Orthodontics and Dentofiwial Orthopedics September 1994

Fig, 4. Pretreatment panoramic x-ray film.

Fig. 3. Pretreatment cephalometric tracing.

TREATMENT

Since the maxillary left canine was beginning to erupt and the maxillary right canine was un- erupted, treatment was delayed for 11 months from the date of the pretreatment records to allow these teeth a proper amount of time to erupt into the arch. After the eruption of these teeth, the patient was sequentially banded, rectangular arch wires were inserted, and high-pull J-hook headgear force was applied to hooks soldered to both arch wires mesial to the canines. After the case was fully banded, sequential mandibular anchorage was pre- pared. After anchorage preparation, the mandibu- lar arch was stabilized, and sequential Class II correction of the posterior teeth was accomplished with a maxillary bulbous loop arch wire, jig force against the maxillary molars, Class II elastics, an- terior vertical elastics, and high-pull headgear

Fig. 5. Pretreatment facial photographs.

r.

force. Treatment time was 20 months. During treatment, there was a 3-month period of very poor elastic and headgear cooperation when no progress was made. A maxillary Hawley retainer and a mandibular fixed canine-to-canine retainer were used for retention. Retention lasted 25 months.

RESULTS ACHIEVED

The posttreatment casts (Fig. 6) showed an Angle Class I interdigitation of the posterior seg- ments and an ideal overjet-overbite relationship. The posttreatment cephalometrie tracing (Fig. 7) confirmed that the ANB angle was reduced to 3.5 ~ The mandibular incisors remained upright as re- flected by an IMPA of 88 ~ The posttreatment FMIA was 70 ~ and the Z-angle virtually remained at its pretreatment value. The posttreatment pan- oramic x-ray film (Fig. 8) showed healthy support- ing tissue and no disease. The posttreatment facial photographs (Fig. 9) confirmed the maintenance of

American Journal of Orthodontics and Dentofilcial Orthopedics l~[cCllllollgh 319 Volume 1 0 6 , N o . 3

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FHIA 70 * IrMA 22* LHPA 88 ~ SNA 79 5* SNB 76* ANB 3.5* OP-Ht 7 ~ AO-BO I ram. Z ANGLE 75* AF}I 67 ram. PFH 51 mm. 1 - SN 97*

Fig. 7. Posttreatment ceph&lometric tracing.

Fig. 6. Posttreatment casts.

the pleasing facial profile. The intrusive forces that were used on the maxillary anterior segment suc- cessfully reduced the excessive gingival display.

The composite cephalometric tracing (Fig. 10) revealed good mandibular response in a downward and forward direction. After 18 months of reten- tion, the third molars were removed.

FIVE-YEAR POSTI 'REATMENT RECORDS

Five years and 8 months after the completion of active treatment, a third set of records was made. The casts (Fig. 11) confirmed the stability of the Angle Class I dental relationship that was achieved during treatment. Some deepening of the overbite that probably contributed to the slight crowding of the mandibular incisors was noted. Cephalometri- cally, the favorable pattern of development contin- ued (Fig. 12). Because of favorable mandibular response, the ANB angle at recall was 0.5 ~ The FMA continued to flatten to 19 ~ and the mandibu- lar incisors uprighted slightly to an IMPA of 87 ~ The FMIA at recall was 74~ its value before

Fig. 8. Posttreatment panoramic x-ray film.

Fig. 9. Posttreatment facial photographs.

treatment. At recall, the Z-angle had increased to 84 ~ .

The composite cephalometric tracing (Fig. 13) confirmed the continued mandibular response, and

320 ~ [ c C t d l o t t g h A m e r i c a n Joz~rna! o f O r t l z o d o n t i c s a n d D e , z t t ~ t c i ( z l O r t h o p e d i c s

S e p t e m b e r 1 9 9 4

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- - - ~ -*~ F~,IA 19" I ~- - ~ - _ r ~, t 1,~4 PA 87* t I i l [ SNA 78 S* II '.�9 SNB 78* I r ANB 0.5 ~ I �9 O P - F ~ I 3*

AO'BO 0 ram. / I , Z ANGLE 84*

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Fig. 10. Pretreatment-posttreatment composite cephalometric Fig. 12. Recall cephalometric tracing. t r a c i n g .

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Fig. 13. Pretreatment, posttreatment, recall cephalometric composite tracing.

Fig. 11. Recall casts.

the flattening of the horizontal planes. The facial photographs (Fig. 14) exhibited the pleasing bal- ance and harmony of the face.

This case has been presented to illustrate the use of the Tweed-Merrifield diagnostic philosophy

American Journal o f Orthodontics and Dentofacial Orthopedics ~, . ~.. , . ~,lli#Cf'ltllOl'"ll 321 Volume 106, P,'o. 3

and o f the Mer r i f i e ld force systems on a nonp re - m o l a r ex t rac t ion case. By using the concep t s o f to ta l space analysis , d i f fe ren t i a l �9 and se- quen t i a l ly a p p l i e d d i rec t iona l force systems, all types o f cases can be t r e a t ed to an o p t i m u m resul t .

REFERENCES

1. Merrifield EL, Cross JJ. Directional force. AM J ORTIIOD 1970;57:435-64.

2. Merrifield LL. The dimensions of the denture. Presented at each Tweed Course. Charles Tweed Memorial Center, Tuc- son, Ariz.

3. Merrifield LL. The systems of directional force. J Charles Tweed Found 1982;10:15-29.

Reprint requests to: Dr. Stephen McCullough 508 W. Vandament Suite 200 Yukon, OK 73099

Fig. 14. Recall facial photographs.

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