American Journal of ORTHODONTICS and DENTOFACIAL ORTHOPEDICS Founded hi 1915
Volume 99 Number 6
J u n e 1991
Copyright © 1991 by the American Association of Orthodontists
CASE REPORT
Sequential directional forces treatment: Two Class II case reports James L. Vaden, DDS, MS* Cookeville; Tenn. Two types of Angle Class II, Division 1 malocclusion that were treated with Tweed-Merrifield directional forces are presented. The cases are entirely different. Each required a different diagnosis, but the results are similar. In both cases the resultant vector of all the orthodontic force systems was upward and forward in direction. (AMJ ORTHOD DENTOFACORTHOP 1991;99:491-504.)
S i n c e the days of orthodontics' distinguished founder, Edward H. Angle, the correction of the Class II malocclusion has continued to stimulate thought and initiate controversy within the specialty of orthodontics. No subject has had as much impact on orthodontic literature or on the clinical practice of orthodontics as that of Class II correction. Angle gave orthodontics the edgewise appliance and a set of "goals" toward which to strive during and after the correction of a malocclusion. Angle's goals of (I) an esthetic face and dentition, (2) a healthy periodontium, (3) dentures that function well, and (4) a stable result are as real in the 1990s as they were in the early 1900s. Of course Angle maintained that one must attain the above-mentioned goals and yet maintain a full complement of teeth., Case,'- Hahn,3 Lischer,4 Tweed,5 Begg, 6 Strang, 7 and many others maintained that it was not possible during the treatment of many types of malocclusion to maintain the full complement of teeth. Tweed, in particular, revolutionized orthodontic thought in the United States in the 1940s, 1950s, and 1960s. He adapted Angle's edgewise appliance to suit his needs. He embraced Angle's goals of treatment, but he maintained that it was impossible to attain these goals *Assistant Professor, Department of Graduate Orthc,dontics. University ofTennessee; in fullfirne private practice in Cookeville. Tenn. 814122797
in many cases with a full complement of teeth. After years of personal research and a careful and meticulous study of his treatment results, Tweed became convinced that the lower anterior teeth should be positioned over the basal bone and that the maxillary anterior teeth should berepositioned to function with these newly positioned mandibular incisors. He concluded that the key to a harmonious and balanced face, denture stability, function, and health of the supporting tissues was the mandibular incisor and its relative upright position in its supporting bone. 8 Anchorage preparation was the cornerstone of Tweed's treatment. In 1936 Tweed wrote: "Anchorage--one of the biggest words in orthodont i a - i s not being utilized to'its utmost in applying the principles of the edgewise arch mechanism in the treatment of Class II, Division I malocclusion, with the result that we are causing more double protrusions than are necessary. ''9 Tweed noticed the aforementioned scenario when he stated: "I would worry along, and finally wind up with an underdeveloped mandible and a horsey looking set of teeth. Why? Because I did not diagnose, study, and prepare anchorage--the mandibular and not the maxillary teeth were the ones that did the moving. '''° Tweed prepared anchorage with coordinated bends in the mandibular arch wire, Class I11 elastics, and maxillary headgear. He developed a technique that required 491
492
Am. J. Orthod. Dentofac. Orthop.
Vaden
June 1991
Upwardand Forward Force Sys)em
Dovmwardand Backv,~rd Force Syslern
i: I !
~
f
#
/
I
\
I
"~j
Flq. 1. Upward and forward force system and downward and backward force system.
Fig. 2. Pretreatment dental casts.
excellent patient cooperation, many arch wire changes, and careful monitoring. In 1970 Merrifield and Cross N published a paper in the AMERICAN J O U R N A L OF ORTHODONTICS outlining the concept of directional forces and the sequelae of these forces in both the denture and the posttreatment facial profile of the orthodontic patient. These investigators stated that the resultant vector of all orthodontic forces should be upward and forward in direction. They maintained that the maxillary incisors should be moved distally and supeiiorly as the lower incisors were uprighted during the correction of a bimaxillary protru-
sion. Merrifield and Cross concluded that control of the Frankfort-mandibular angle (FMA), the occlusal plane, and the palatal plane was essential if, during the course of treatment, a resultant upward and forward force vector was to be a reality. They stated that if the proper direction of force was not used, the resultant force vector would be downward and backward, increasing the FMA and steepening the occlusal plane. The net result of all this was that the B point dropped down and back, causing a lengthened face, undertorqued maxillary anterior teeth, and a "gingivar' smile (Fig. 1). Tweed's system of mandibular anchorage prepara-
Vol,me 99 Number 6
C as e r e por t
•.
493
\/
!
l - FIqA 2 3
- IMPA - I~IIA
4 - SNA 5
SNB -ANB - OP-FI 1 - Z ANGLE AFH -
6 7 8 9 l0 -
AO-BO
30 °
j9
,99o 51 ° 83 °
7bo 7° 11° 58 o 65nrn 6n m
Fig. 3. Tracing of pretreatment lateral cephalometric radiograph.
tion, augmented by directional forces, was drastically altered in 1978, when Levern Merrifield ~-" introduced "Sequential Mandibular Anchorage Preparation." Merrifield reasoned that second-order bends placed at one setting in the posterior part o f the mandibular arch wire were very antagonistic to the teeth in the mandibular anterior segment. He stated that the mandibular anterior teeth could not support anchorage preparation of the mandibular posterior teeth and that Class III forces, in most cases, did not "pull" from the right direction. Merrifield's 10-2 System of mandibular anchorage preparation uses 10 teeth as an anchorage unit. The two remaining teeth in the arch are tipped to their desired "anchorage prepared" positions. The 10 teeth that are used as an anchorage unit are aided with an extraoral directional f o r c e - - a high-pull headgear attached to the anterior part of the mandibular arch wire." It has been estimated that 65% of the cases an orthodontist treats involve Angle Class I1 malocclusions. Presented in this article are the pretreatment, posttreatment, and recovery records of two patients with Class II, Division 1 malocclusions. Though these malocclusions presented different problems and required different extraction sequences, both cases were treated with upward and forward force systems. CASE 1
The Class 1I, Division 1 case had both a bimaxillary protrnsion and crowding. Total dc~tition space analysis with differential diagnosis" made it very clear that the four first pre-
molars had to be extracted. Only by careful use of the space gained from.the extractions could the crowding and protrusion be reduced and facial balance and harmony be attained. The case was treated with a nontorqued, nonangulated 0.022inch edgewise appliance using Tweed-Merrifield directional forces. Active treatment time was 23 months. The retention period was 22 months. Diagnosis
The dental casts (Fig. 2) exhibited a Class II relationship of the buccal segments. The mandibular incisors were crowded and were labially flared; the entire mandibular arch was skewed to the right side. The maxillary right lateral incisor was lingually locked between the canine and the central incisor, and the maxillary midline was deviated to the right. In the radiographic evaluation, the prctreatment cephalometric tracing shows the Angle Class II skeletal pattern and the dentoalveolar protrusion (Fig. 3). An IMPA of 99 °, an FMIA of 51 °, and an ANI3.angle of 7 ° indicate the protrusion and reflect the skeletal problem. The frontal and lateral facial photographs of the patient in Fig. 4 illustrate a convex facial profile with a marked protrusion of the lips. The lower lip is particularly protruded and unsight.ly. Treatment
The patient's teeth were fully banded with a standard 0.022-inch edgewise appliance. J-hook high-pull headgear force was applied to both the maxillary and mandibular canines after banding. After leveling, alignment, and canine retraction, 0.019 x 0.025-inch closing loop arch ,,vires were placed. Headgear force was continued. A mandibular stabi-
494
Vaden
Am. J. Orthod. Dentofac. Orthop.
June 1991
Fig. 4. Pretreatment facial photographs.
99 ° to 86°), the FMIA was increased 15° (from 51 ° to 66°), and the ANB angle was decreased.from 7° to 4 °. An intraoral panoramic radiograph taken during retention exhibits root paralleling (Fig. 8). The mandibular right first molar has some condensing osteitis, which is asymptomatic. All four third molars have been r~moved. As shown in the facial photographs (Fig. 9), the facial profile has been made less convex by soft tissue remodeling. The prelreatment and posttreatment composite cephalometric tracings (Fig. 10) show that the mandible moved slightly downward and forward relative to sella-nasion (SN). The net effect of upward and forward force was that the mandibular incisors were uprighted, and the maxillary anterior teeth were moved distally and superiorly.
Fig. 5. Denture correction arch wires with Class II elastics and anterior vertical elastics.
lizing arch wire was fabricated after mandibular space closure and mandibular anchorage preparation. Class II elastics were used only in conjunction with anterior vertical elastics (Fig. 5), and a J-hook high-pull headgear was attached to hooks on the maxillary arch wire. The resultant vector of this force system was upward and forward. Treatment was completed with ideal arch wires, Class II elastics, anterior vertical elastics, and cusp-seating elastics. A J-hook high-pull headgear attached to the maxillary arch wire was worn 10 to 12 hours a day during finishing procedures.
Results achieved The posttreatment dental casts show the Class I interdigitation of the buccal segments (Fig 6). The crowding was relieved, and the midline deviation was corrected. In a,radiographic evaluation, the cephalometric tracing (Fig. 7) revealed the lower incisors wez:e uprighted 13° (from
Retention
The case was retained for 22 months with a maxillary Hawley retainer and a fixed mandibular canine-to-canine retainer. All four third molars were removed during the retention period.
Posttreatment stability Recovery records were made 4 years after the end of a 22month retention period. The 6-year recovery dental casts reveal the settled occlusion and a stable buccal segment correction (Fig. 11). In the radiographic evaluation, the recovery cephalometric tracing (Fig. 12) exhibits a trend toward a more upright denture. As an example, the 1MPA has decreased to 84° as a result of the continued uprighting of the mandibular incisors. Six-year recovery facial photographs show continued improvement of the facial profile (Fig. 13). The three composite cephalometric tracings, all superimposed on SN at sella, reveal continued downward and forward development (Fig. 14). Both the intrusion of the maxillary in-
Volume 99 Number 6
Case report
-
\
495
~"
Fig. 6. Posttreatment dental casts.
Posttreatment
F'MA I,MPA FMIA SNA SNB ANB OP-Ftl Z AFI t AO-BO
28 86 66 80 76 4 10 68 67rrm 5rrrn
Fig. 7. Tracing of posttreatment cephalometric radiograph.
cisors and the uprighting of the mandibular incisors have remained stable.
CASE 2 The diagnosis of the following case was also accomplished with the use of l~Aerrifield's total dentition space analysis with differential diagnosis. This case, although it involved an Angle Class II malocclusion, did not exhibit as much lower anterior crowding or lowcr denture protrusion as
the previous case. It was necessary, however, to gain space in the mandibular arch (I) to correct the crowding that was present and (2) to correct the Class II molar relationship by moving the mandibular first molars mesially. Therefore the mandibular second premolars were removed. The first premolars were removed from the maxillary arch to facilitate maxillary anterior retraction. This combination of maxillary first premolar and mandibular second premolar extractions was deemed necessary to correct the malocclusion, maintain
496
Vaden
Am. J. Orthod. Dentofac. Orthop. June 1991
Fig. 8. Posttreatmentpanoramic radiograph.
%,
Fig. 9. Posttreatment facial photographs.
J Fig. 10. Composite of pretreatment and posttreatment tracings of cephalometric radiographs.
Volume 99 Number 6
Case report
497
Fig. 11. Recovery casts.
/
LJ
F~.IA IMPA FMIA SNA SNB ANB OP-FI-t Z AFI I AO-BO
29 84 67 80 77 3 6 65 67t'~m 5ram
Fig. 12. Tracing of recovery cephalometric radiograph.
the teeth over the basal bone, and restore the facial balance and harmony. An 0.022-inch nonangulated, nontorqued appliance was used. The force system uscd was the TwecdMerrifield directional forces system.
Diagnosis The dental casts show an Angle Class II, Division !, subdivision right malocclusion (Fig. 15). The mandibular incisors were relatively upright over their bony support, and there was only 3 mm of mandibular anterior crowding. The maxillary incisors were flared. In the radiographic evaluation, the eephalometric tracing
(Fig. 16) reveals the relatively upright mandibular incisors, the maxillary protrusion, and an ANB angle of 5°. The oeclusal plane value was a rather steep 14°. The frontal and lateral facial photographs of the patient show a convex facial profile with maxillary lip fullness (Fig. 17).
Treatment The patient's teeth were banded with a standard 0.022inch edgewise appliance. J-hook headgear force was applied to the maxillary canines and to the mandibular canines during leveling. After leveling of the mandibular arch, an
498
Vaden
Am. J. Orthod. Dentofac. Orthop. June 1991
|
.q
Fig. 13. Recovery facial photographs.
U Pretreatment Posltreatrnenl ...... Recovery .............
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Fig. 14. Composite of pretreatment, posttreatment, and recovery tracings.
0.018 x 0.025-inch arch wire was fabricated with a closing loop in the mandibular second premolar extraction site (Fig. 18). The loops were activated, and the mandibular molars were moved forward to close the mandibular extraction space. Canine retraction was continued in the maxillary arch with the J-hook headgear. After the maxillary canines were retracted, the remaining space was closed with an 0.020 × 0.025-inch closing loop arch wire. J-hook high-pull headgear attached to hooks soldered gingival to the arch wire between the central and lateral incisors on the maxillary closing loop
arch wire was worn. After mandibular space closure, the mandibular arch was again leveled, and mandibular anchorage was prepared according to the steps Of sequential anchorage preparation. Mandibular anchorage was prepared (1) to upright the molars into the extraction space, (2) to control the occlusal plane, and (3) to disclude the second molars so that they could settle into a functional occlusion during the retention phase of treatment. Only I month of Class II elastic force was required. The Class II elastics were used in conjunction with an anterior vertical elastic and a high-pull headgear at-
Volume 99 Number 6
Case report
499
Fig. 15. Pretreatment dental casts.
LJ
Pretreatment FblA IMPA FMIA SNA SNB ANB OP-FH Z AFH AO-BO
26 93 63 77 72 5 14 68 61ram 2ram
Fig. 16. Tracing of pretreatment cephalometric radiograph.
tached to hooks soldered on the maxillary arch wire distal and gingival to the central incisors. Ideal arch wires were then fabricated, and the case was finished with cusp-seating elastics and the J-hook high-pull headgear. Results achieved
The posttreatment dental casts show Class I interdigitation of the buccal segments (Fig. 19). Note the mandibular anchorage preparation and the "treatment occlusion." In the radiographic evaluation, the ccphalometric tracing
(Fig. 20) revealed the FMA remained stable at 26 °, and the occlusal plane flattened 3 °. An intraoral panoramic radiograph (Fig. 21) taken during retention illustrates root paralleling. The mandibular first molar roots have been moved forward into the mandibular second premolar extraction sites. Ttie facial photographs show the profile was softened and made less convex (Fig. 22). Prctreatment and posttreatment composite tracings illustrate the downward and forward movement of the mandible (Fig. 23). Note the intrusion and distal movement of the
500
Vaden
Am. J. Orthod. Dentofac. Orthop. June 1991
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Fig. 17. Pretreatment facial photographs.
Fig. 18. Closing loop in mandibular second premolar extraction site.
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Fig. 19. Posttreatment dental casts.
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Volume 99 Number 6
Case report
Posttreatment 26, 84 70 73 72
FMA
IMPA FI~IIA
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1
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Fig. 20. Tracing of posttreatment cephalometric radiograph.
Fig. 21. Posttreatment panoramic radiograph.
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i Fig. 22. Posttreatment facial photographs.
501
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Fig. 23. Composite of pretreatment and posttreatment tracings of cephatometric radiographs.
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Fig. 24. Recovery casts.
maxillary incisors. Again, this is an example of treatment with directional forces during which upward and forward force systems are used.
Retention The case was retained for 23 months with a maxillary Hawley retainer and a fixed mandibular canine-to-canine retainer.
Posttreatment stability
The recovery records were made approximately 3 years after the patient entered retention. The records show a stable and continually improving treatment result. The dental casts (Fig. 24) show that the second molars have settled nicely. The occlusion and the arch alignment have remained stable. In the radiographic evaluation, the cephalometric tracing
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Case report
Number 6
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o
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Fig. 26. Recovery facial photographs.
shows the mandible has continued to move downward and forward relative to cranial base (Fig. 25). The continued uprighting of the mandibular incisors and the continued stability of the occlusal plane are sequelae of the upward and forward force system. The recovery facial photographs show continued improvement in the facial profile and a good balance of facial proportions (Fig. 26).
The pretreatment, posttreatment, and recovery composite cephalometric tracings superimposed on SN at sella show a normal and favorable development of the facial structures (Fig. 27). Incisor position, point A retraction, and the Class II correction have remained stable. Both o f these cases, although they involved totally different types o f Class II malocclusion, show the versatility o f the Tweed-Merrifield 10-2 directional forces
504
Vaden
Am. J. Orthod. Dentofac. Orthop. June 1991
,,,,/;
.~.'..
s
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"".~ Recovery . . . . . . . . . . . . .
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Fig. 27. Composite of pretreatment, posttreatment, and recovery tracings.
system. Both are illustrative o f the c o n c e p t o f the use o f u p w a r d and forward force s y s t e m s . Proper treatment o f the first case required c o m p l e t e p r e s e r v a t i o n o f all extraction space for protrusion reduction and anterior tooth alignment. T r e a t m e n t o f the s e c o n d case required almost total loss o f m a n d i b u l a r a n c h o r a g e . B e c a u s e o f l o w e r incisor position, all the m a n d i b u l a r extraction space had to be c l o s e d b y m o v i n g the m a n d i b u l a r molars mesially. T h o u g h both the cases r e q u i r e d different mechanics, the resultant v e c t o r o f all the forces applied to the dentures was the s a m e - - u p w a r d and forward in direction.
REFERENCES I. Angle Ell. Treatment of malocclusion of the teeth--Angle's system. 7th Ed. Philadelphia: SS White Dental Mfg. Co.; 1907. 2. Case C. A practical treatise on the techniques and principles of dental orthopedia. Chicago: CS Case; 1921. 3. Hahn GW. Retention--the stepchild of orthodontia. Angle Orthod 1944;14:312. 4. Lischer BE. Principles and methods of orthodontics. Philadelphia: Lea & Febiger;1912. 5. Tweed CH. Indications for the extraction of teeth in orthodontic procedures. AM J ORItlOD ORALSURG 1944;30:405-28.
6. Begg PR. Begg orthodontic theory and technique. Philadelphia: WB Saunders; 1971. 7. Strang RHW. Factors of influence in producing a stable result in the treatment of malocclusion. AM J ORTHODORAL SUR~ 1946;32:313-32. 8. Tweed CH. A philosophy of orthodontic treatment. AM J ORTIIOD ORAL SURG 1945;31:74-103. 9. Tweed CH. The application of the principles of the edgewise arch in the treatment of Class II, Division I: Part II. Angle Orthod 1936;16:256. I0. Tweed CH. The application of the principles of the edgewise arch in the treatment of Class II, Division I malocclusion: Part I. Angle Orthod 1936;6:208: 11. Merrifield LL, Cross JJ. Directional forces. AM J ORTttOD 1970;57:435-64. 12. Merrifield LL. The systems of directional force. Charles Tweed Foundation. 1982;10:15-29. 13. Merrifield LL. Edgewise sequential directional force technology. Charles H. Tweed International Foundation 1986;14:22-37. 14. Merrifield LL. Differential diagnosis with total space analysis. J Charles Tweed Foundation. 1978;6:10-5. Reprint requests to:
Dr. James L. Vaden 308 East First St. Cookeville, TN 38501
Volume 99 Number 6
J u n e 1991
Copyright © 1991 by the American Association of Orthodontists
CASE REPORT
Sequential directional forces treatment: Two Class II case reports James L. Vaden, DDS, MS* Cookeville; Tenn. Two types of Angle Class II, Division 1 malocclusion that were treated with Tweed-Merrifield directional forces are presented. The cases are entirely different. Each required a different diagnosis, but the results are similar. In both cases the resultant vector of all the orthodontic force systems was upward and forward in direction. (AMJ ORTHOD DENTOFACORTHOP 1991;99:491-504.)
S i n c e the days of orthodontics' distinguished founder, Edward H. Angle, the correction of the Class II malocclusion has continued to stimulate thought and initiate controversy within the specialty of orthodontics. No subject has had as much impact on orthodontic literature or on the clinical practice of orthodontics as that of Class II correction. Angle gave orthodontics the edgewise appliance and a set of "goals" toward which to strive during and after the correction of a malocclusion. Angle's goals of (I) an esthetic face and dentition, (2) a healthy periodontium, (3) dentures that function well, and (4) a stable result are as real in the 1990s as they were in the early 1900s. Of course Angle maintained that one must attain the above-mentioned goals and yet maintain a full complement of teeth., Case,'- Hahn,3 Lischer,4 Tweed,5 Begg, 6 Strang, 7 and many others maintained that it was not possible during the treatment of many types of malocclusion to maintain the full complement of teeth. Tweed, in particular, revolutionized orthodontic thought in the United States in the 1940s, 1950s, and 1960s. He adapted Angle's edgewise appliance to suit his needs. He embraced Angle's goals of treatment, but he maintained that it was impossible to attain these goals *Assistant Professor, Department of Graduate Orthc,dontics. University ofTennessee; in fullfirne private practice in Cookeville. Tenn. 814122797
in many cases with a full complement of teeth. After years of personal research and a careful and meticulous study of his treatment results, Tweed became convinced that the lower anterior teeth should be positioned over the basal bone and that the maxillary anterior teeth should berepositioned to function with these newly positioned mandibular incisors. He concluded that the key to a harmonious and balanced face, denture stability, function, and health of the supporting tissues was the mandibular incisor and its relative upright position in its supporting bone. 8 Anchorage preparation was the cornerstone of Tweed's treatment. In 1936 Tweed wrote: "Anchorage--one of the biggest words in orthodont i a - i s not being utilized to'its utmost in applying the principles of the edgewise arch mechanism in the treatment of Class II, Division I malocclusion, with the result that we are causing more double protrusions than are necessary. ''9 Tweed noticed the aforementioned scenario when he stated: "I would worry along, and finally wind up with an underdeveloped mandible and a horsey looking set of teeth. Why? Because I did not diagnose, study, and prepare anchorage--the mandibular and not the maxillary teeth were the ones that did the moving. '''° Tweed prepared anchorage with coordinated bends in the mandibular arch wire, Class I11 elastics, and maxillary headgear. He developed a technique that required 491
492
Am. J. Orthod. Dentofac. Orthop.
Vaden
June 1991
Upwardand Forward Force Sys)em
Dovmwardand Backv,~rd Force Syslern
i: I !
~
f
#
/
I
\
I
"~j
Flq. 1. Upward and forward force system and downward and backward force system.
Fig. 2. Pretreatment dental casts.
excellent patient cooperation, many arch wire changes, and careful monitoring. In 1970 Merrifield and Cross N published a paper in the AMERICAN J O U R N A L OF ORTHODONTICS outlining the concept of directional forces and the sequelae of these forces in both the denture and the posttreatment facial profile of the orthodontic patient. These investigators stated that the resultant vector of all orthodontic forces should be upward and forward in direction. They maintained that the maxillary incisors should be moved distally and supeiiorly as the lower incisors were uprighted during the correction of a bimaxillary protru-
sion. Merrifield and Cross concluded that control of the Frankfort-mandibular angle (FMA), the occlusal plane, and the palatal plane was essential if, during the course of treatment, a resultant upward and forward force vector was to be a reality. They stated that if the proper direction of force was not used, the resultant force vector would be downward and backward, increasing the FMA and steepening the occlusal plane. The net result of all this was that the B point dropped down and back, causing a lengthened face, undertorqued maxillary anterior teeth, and a "gingivar' smile (Fig. 1). Tweed's system of mandibular anchorage prepara-
Vol,me 99 Number 6
C as e r e por t
•.
493
\/
!
l - FIqA 2 3
- IMPA - I~IIA
4 - SNA 5
SNB -ANB - OP-FI 1 - Z ANGLE AFH -
6 7 8 9 l0 -
AO-BO
30 °
j9
,99o 51 ° 83 °
7bo 7° 11° 58 o 65nrn 6n m
Fig. 3. Tracing of pretreatment lateral cephalometric radiograph.
tion, augmented by directional forces, was drastically altered in 1978, when Levern Merrifield ~-" introduced "Sequential Mandibular Anchorage Preparation." Merrifield reasoned that second-order bends placed at one setting in the posterior part o f the mandibular arch wire were very antagonistic to the teeth in the mandibular anterior segment. He stated that the mandibular anterior teeth could not support anchorage preparation of the mandibular posterior teeth and that Class III forces, in most cases, did not "pull" from the right direction. Merrifield's 10-2 System of mandibular anchorage preparation uses 10 teeth as an anchorage unit. The two remaining teeth in the arch are tipped to their desired "anchorage prepared" positions. The 10 teeth that are used as an anchorage unit are aided with an extraoral directional f o r c e - - a high-pull headgear attached to the anterior part of the mandibular arch wire." It has been estimated that 65% of the cases an orthodontist treats involve Angle Class I1 malocclusions. Presented in this article are the pretreatment, posttreatment, and recovery records of two patients with Class II, Division 1 malocclusions. Though these malocclusions presented different problems and required different extraction sequences, both cases were treated with upward and forward force systems. CASE 1
The Class 1I, Division 1 case had both a bimaxillary protrnsion and crowding. Total dc~tition space analysis with differential diagnosis" made it very clear that the four first pre-
molars had to be extracted. Only by careful use of the space gained from.the extractions could the crowding and protrusion be reduced and facial balance and harmony be attained. The case was treated with a nontorqued, nonangulated 0.022inch edgewise appliance using Tweed-Merrifield directional forces. Active treatment time was 23 months. The retention period was 22 months. Diagnosis
The dental casts (Fig. 2) exhibited a Class II relationship of the buccal segments. The mandibular incisors were crowded and were labially flared; the entire mandibular arch was skewed to the right side. The maxillary right lateral incisor was lingually locked between the canine and the central incisor, and the maxillary midline was deviated to the right. In the radiographic evaluation, the prctreatment cephalometric tracing shows the Angle Class II skeletal pattern and the dentoalveolar protrusion (Fig. 3). An IMPA of 99 °, an FMIA of 51 °, and an ANI3.angle of 7 ° indicate the protrusion and reflect the skeletal problem. The frontal and lateral facial photographs of the patient in Fig. 4 illustrate a convex facial profile with a marked protrusion of the lips. The lower lip is particularly protruded and unsight.ly. Treatment
The patient's teeth were fully banded with a standard 0.022-inch edgewise appliance. J-hook high-pull headgear force was applied to both the maxillary and mandibular canines after banding. After leveling, alignment, and canine retraction, 0.019 x 0.025-inch closing loop arch ,,vires were placed. Headgear force was continued. A mandibular stabi-
494
Vaden
Am. J. Orthod. Dentofac. Orthop.
June 1991
Fig. 4. Pretreatment facial photographs.
99 ° to 86°), the FMIA was increased 15° (from 51 ° to 66°), and the ANB angle was decreased.from 7° to 4 °. An intraoral panoramic radiograph taken during retention exhibits root paralleling (Fig. 8). The mandibular right first molar has some condensing osteitis, which is asymptomatic. All four third molars have been r~moved. As shown in the facial photographs (Fig. 9), the facial profile has been made less convex by soft tissue remodeling. The prelreatment and posttreatment composite cephalometric tracings (Fig. 10) show that the mandible moved slightly downward and forward relative to sella-nasion (SN). The net effect of upward and forward force was that the mandibular incisors were uprighted, and the maxillary anterior teeth were moved distally and superiorly.
Fig. 5. Denture correction arch wires with Class II elastics and anterior vertical elastics.
lizing arch wire was fabricated after mandibular space closure and mandibular anchorage preparation. Class II elastics were used only in conjunction with anterior vertical elastics (Fig. 5), and a J-hook high-pull headgear was attached to hooks on the maxillary arch wire. The resultant vector of this force system was upward and forward. Treatment was completed with ideal arch wires, Class II elastics, anterior vertical elastics, and cusp-seating elastics. A J-hook high-pull headgear attached to the maxillary arch wire was worn 10 to 12 hours a day during finishing procedures.
Results achieved The posttreatment dental casts show the Class I interdigitation of the buccal segments (Fig 6). The crowding was relieved, and the midline deviation was corrected. In a,radiographic evaluation, the cephalometric tracing (Fig. 7) revealed the lower incisors wez:e uprighted 13° (from
Retention
The case was retained for 22 months with a maxillary Hawley retainer and a fixed mandibular canine-to-canine retainer. All four third molars were removed during the retention period.
Posttreatment stability Recovery records were made 4 years after the end of a 22month retention period. The 6-year recovery dental casts reveal the settled occlusion and a stable buccal segment correction (Fig. 11). In the radiographic evaluation, the recovery cephalometric tracing (Fig. 12) exhibits a trend toward a more upright denture. As an example, the 1MPA has decreased to 84° as a result of the continued uprighting of the mandibular incisors. Six-year recovery facial photographs show continued improvement of the facial profile (Fig. 13). The three composite cephalometric tracings, all superimposed on SN at sella, reveal continued downward and forward development (Fig. 14). Both the intrusion of the maxillary in-
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Fig. 6. Posttreatment dental casts.
Posttreatment
F'MA I,MPA FMIA SNA SNB ANB OP-Ftl Z AFI t AO-BO
28 86 66 80 76 4 10 68 67rrm 5rrrn
Fig. 7. Tracing of posttreatment cephalometric radiograph.
cisors and the uprighting of the mandibular incisors have remained stable.
CASE 2 The diagnosis of the following case was also accomplished with the use of l~Aerrifield's total dentition space analysis with differential diagnosis. This case, although it involved an Angle Class II malocclusion, did not exhibit as much lower anterior crowding or lowcr denture protrusion as
the previous case. It was necessary, however, to gain space in the mandibular arch (I) to correct the crowding that was present and (2) to correct the Class II molar relationship by moving the mandibular first molars mesially. Therefore the mandibular second premolars were removed. The first premolars were removed from the maxillary arch to facilitate maxillary anterior retraction. This combination of maxillary first premolar and mandibular second premolar extractions was deemed necessary to correct the malocclusion, maintain
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Am. J. Orthod. Dentofac. Orthop. June 1991
Fig. 8. Posttreatmentpanoramic radiograph.
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Fig. 9. Posttreatment facial photographs.
J Fig. 10. Composite of pretreatment and posttreatment tracings of cephalometric radiographs.
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Fig. 11. Recovery casts.
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F~.IA IMPA FMIA SNA SNB ANB OP-FI-t Z AFI I AO-BO
29 84 67 80 77 3 6 65 67t'~m 5ram
Fig. 12. Tracing of recovery cephalometric radiograph.
the teeth over the basal bone, and restore the facial balance and harmony. An 0.022-inch nonangulated, nontorqued appliance was used. The force system uscd was the TwecdMerrifield directional forces system.
Diagnosis The dental casts show an Angle Class II, Division !, subdivision right malocclusion (Fig. 15). The mandibular incisors were relatively upright over their bony support, and there was only 3 mm of mandibular anterior crowding. The maxillary incisors were flared. In the radiographic evaluation, the eephalometric tracing
(Fig. 16) reveals the relatively upright mandibular incisors, the maxillary protrusion, and an ANB angle of 5°. The oeclusal plane value was a rather steep 14°. The frontal and lateral facial photographs of the patient show a convex facial profile with maxillary lip fullness (Fig. 17).
Treatment The patient's teeth were banded with a standard 0.022inch edgewise appliance. J-hook headgear force was applied to the maxillary canines and to the mandibular canines during leveling. After leveling of the mandibular arch, an
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0.018 x 0.025-inch arch wire was fabricated with a closing loop in the mandibular second premolar extraction site (Fig. 18). The loops were activated, and the mandibular molars were moved forward to close the mandibular extraction space. Canine retraction was continued in the maxillary arch with the J-hook headgear. After the maxillary canines were retracted, the remaining space was closed with an 0.020 × 0.025-inch closing loop arch wire. J-hook high-pull headgear attached to hooks soldered gingival to the arch wire between the central and lateral incisors on the maxillary closing loop
arch wire was worn. After mandibular space closure, the mandibular arch was again leveled, and mandibular anchorage was prepared according to the steps Of sequential anchorage preparation. Mandibular anchorage was prepared (1) to upright the molars into the extraction space, (2) to control the occlusal plane, and (3) to disclude the second molars so that they could settle into a functional occlusion during the retention phase of treatment. Only I month of Class II elastic force was required. The Class II elastics were used in conjunction with an anterior vertical elastic and a high-pull headgear at-
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Fig. 15. Pretreatment dental casts.
LJ
Pretreatment FblA IMPA FMIA SNA SNB ANB OP-FH Z AFH AO-BO
26 93 63 77 72 5 14 68 61ram 2ram
Fig. 16. Tracing of pretreatment cephalometric radiograph.
tached to hooks soldered on the maxillary arch wire distal and gingival to the central incisors. Ideal arch wires were then fabricated, and the case was finished with cusp-seating elastics and the J-hook high-pull headgear. Results achieved
The posttreatment dental casts show Class I interdigitation of the buccal segments (Fig. 19). Note the mandibular anchorage preparation and the "treatment occlusion." In the radiographic evaluation, the ccphalometric tracing
(Fig. 20) revealed the FMA remained stable at 26 °, and the occlusal plane flattened 3 °. An intraoral panoramic radiograph (Fig. 21) taken during retention illustrates root paralleling. The mandibular first molar roots have been moved forward into the mandibular second premolar extraction sites. Ttie facial photographs show the profile was softened and made less convex (Fig. 22). Prctreatment and posttreatment composite tracings illustrate the downward and forward movement of the mandible (Fig. 23). Note the intrusion and distal movement of the
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Am. J. Orthod. Dentofac. Orthop. June 1991
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Fig. 18. Closing loop in mandibular second premolar extraction site.
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Case report
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FMA
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Fig. 21. Posttreatment panoramic radiograph.
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maxillary incisors. Again, this is an example of treatment with directional forces during which upward and forward force systems are used.
Retention The case was retained for 23 months with a maxillary Hawley retainer and a fixed mandibular canine-to-canine retainer.
Posttreatment stability
The recovery records were made approximately 3 years after the patient entered retention. The records show a stable and continually improving treatment result. The dental casts (Fig. 24) show that the second molars have settled nicely. The occlusion and the arch alignment have remained stable. In the radiographic evaluation, the cephalometric tracing
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Fig. 26. Recovery facial photographs.
shows the mandible has continued to move downward and forward relative to cranial base (Fig. 25). The continued uprighting of the mandibular incisors and the continued stability of the occlusal plane are sequelae of the upward and forward force system. The recovery facial photographs show continued improvement in the facial profile and a good balance of facial proportions (Fig. 26).
The pretreatment, posttreatment, and recovery composite cephalometric tracings superimposed on SN at sella show a normal and favorable development of the facial structures (Fig. 27). Incisor position, point A retraction, and the Class II correction have remained stable. Both o f these cases, although they involved totally different types o f Class II malocclusion, show the versatility o f the Tweed-Merrifield 10-2 directional forces
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system. Both are illustrative o f the c o n c e p t o f the use o f u p w a r d and forward force s y s t e m s . Proper treatment o f the first case required c o m p l e t e p r e s e r v a t i o n o f all extraction space for protrusion reduction and anterior tooth alignment. T r e a t m e n t o f the s e c o n d case required almost total loss o f m a n d i b u l a r a n c h o r a g e . B e c a u s e o f l o w e r incisor position, all the m a n d i b u l a r extraction space had to be c l o s e d b y m o v i n g the m a n d i b u l a r molars mesially. T h o u g h both the cases r e q u i r e d different mechanics, the resultant v e c t o r o f all the forces applied to the dentures was the s a m e - - u p w a r d and forward in direction.
REFERENCES I. Angle Ell. Treatment of malocclusion of the teeth--Angle's system. 7th Ed. Philadelphia: SS White Dental Mfg. Co.; 1907. 2. Case C. A practical treatise on the techniques and principles of dental orthopedia. Chicago: CS Case; 1921. 3. Hahn GW. Retention--the stepchild of orthodontia. Angle Orthod 1944;14:312. 4. Lischer BE. Principles and methods of orthodontics. Philadelphia: Lea & Febiger;1912. 5. Tweed CH. Indications for the extraction of teeth in orthodontic procedures. AM J ORItlOD ORALSURG 1944;30:405-28.
6. Begg PR. Begg orthodontic theory and technique. Philadelphia: WB Saunders; 1971. 7. Strang RHW. Factors of influence in producing a stable result in the treatment of malocclusion. AM J ORTHODORAL SUR~ 1946;32:313-32. 8. Tweed CH. A philosophy of orthodontic treatment. AM J ORTIIOD ORAL SURG 1945;31:74-103. 9. Tweed CH. The application of the principles of the edgewise arch in the treatment of Class II, Division I: Part II. Angle Orthod 1936;16:256. I0. Tweed CH. The application of the principles of the edgewise arch in the treatment of Class II, Division I malocclusion: Part I. Angle Orthod 1936;6:208: 11. Merrifield LL, Cross JJ. Directional forces. AM J ORTttOD 1970;57:435-64. 12. Merrifield LL. The systems of directional force. Charles Tweed Foundation. 1982;10:15-29. 13. Merrifield LL. Edgewise sequential directional force technology. Charles H. Tweed International Foundation 1986;14:22-37. 14. Merrifield LL. Differential diagnosis with total space analysis. J Charles Tweed Foundation. 1978;6:10-5. Reprint requests to:
Dr. James L. Vaden 308 East First St. Cookeville, TN 38501
