Class II correction with an intermaxillary fixed noncompliance -Departement orthodontic- mansoura university _ Egypt

1. Supervisor prof : Maher fouda
By : ameen mohammed

2.  Class II malocclusion is one of the most common problems
presenting to orthodontists. Skeletally, a prognathic
maxilla, a retrognathic mandible, or a combination of
the two is a possible etiology for this malocclusion
 Studies in the literature 9–12 report that Class II
malocclusion is more commonly associated with
mandibular retrognathism than with maxillary prognathism

3.  Stahl et al. reported that features of a skeletal Class II occlusion
develop early in the deciduous dentition and do not tend to self-
correct with age, implying that some sort of intervention is
necessary to achieve correction.
 Depending on the patient’s growth status, treatment options
commonly include use of functional appliances or fixed
functional appliances (FFAs) to enhance mandibular growth,
headgear to restrict maxillary growth, camouflage by extraction
of upper and/or lower premolars, or surgical correction of the
underlying skeletal discrepancy in patients in whom facial growth
has been completed.

4.  The term functional appliance refers to a group of
appliances that posture the mandible forward in an
attempt to stimulate mandibular growth.
 Typically a functional appliance is advocated for a
minimum of 12 hours per day for 6 to 9 months to observe
dentoskeletal changes. Thus patient compliance is critical to
the success of removable functional appliances.
 In general, the factors associated with patient compliance
are age, nature of the treatment delivered, and
psychosocial characteristics of the individual patient.

5.  The compliance with treatment is better in adults than in
children and that younger children are more compliant
with treatment than are adolescents.
 The most growth modulation procedures are undertaken in
the adolescent phase, proficient patient compliance may
be difficult to obtain in certain patients. Removable
appliances such as headgear and functional appliances are
usually rejected by patients due to discomfort, pain,
restriction, and constraints on physical activity and
movement

6.  To eliminate patient compliance for Class II correction,
the use of non–patient-compliance-based FFAs was first
propagated by Emil Herbst in 1905 with the
Herbst appliance.
The appliance never really gained popularity until Pancherz
revived it in the 1970s. Since then there have been
numerous modifications of the rigid Herbst appliance and
various other FFAs have also been reported in the literature.

7. Herbst appliance.

8.  These FFAs may be broadly classified as rigid, flexible,
and semirigid fixed functional appliances.
 The major difference between functional appliances and
FFAs is that the mandible is forcefully postured in an
anterior position with FFAs with the help of inter-arch
anchorage using the maxillary denture base as the anchor
unit.

9.  Using the concept of equilibrium, it can be understood that when a
rigid FFA is placed in the mouth, the appliance is in static
equilibrium. This essentially means that when there is a mesial or
forward directed force on the lower arch, there exists an equal and
opposite distal or backward directed force on the upper arch. This
effect has been proved by cephalometric studies as the “headgear
effect” of FFAs.
 Apart from the “skeletal” effects on the denture bases, effects on the
dentition such as retroclination of maxillary incisors, proclination of
mandibular incisors, distalization of upper molars and mesialization of
lower molars, and clockwise rotation of the occlusal plane 38 have
also been observed with FFAs.

10. Cephalometric analysis can be performed to evaluate the cranial base,
the relationship of the maxilla to the cranial base, the mandible’s size and
position relative to the cranial base, the relationship between the maxilla
and the mandible, the vertical dimension, maxillary and mandibular
dentition, and soft tissue. Table 13-1 provides an example of such
analysis

11. DIAGNOSIS AND TREATMENT PLANNING
A relatively easy, quick, and reliable way to assess the outcome
with a functional appliance or FFA is a visualized treatment objective
(VTO). The patient is asked to posture the mandible forward, obtaining
anterior incisal contact with the posterior teeth in a Class I or super
Class I relationship. If the profile of the patient improves, it indicates that
the patient may be a good candidate for functional jaw orthopedics
A Profile view of Class II patient
before treatment.
B, Visualized treatment objective
(VTO). Patient is asked to posture
the mandible forward
to estimate improvement in the
soft tissue profile. Note the
improvement in the soft tissue
profile of the patient.

12. If on posturing the mandible forward the profile does not
show improvement, the patient may not be an ideal candidate
for a functional appliance and other methods for Class II
could be considered or a prefunctional orthodontic phase may
be required
A, Profile view of Class II
patient before treatment.
B, Visualized treatment
objective (VTO) of the
patient. Note that the soft
tissue profile of the patient
is not improved, indicating
that the patient may not be
an ideal case for functional
appliances.

13. As a general rule, a functional appliance (FFA) is most
ideally indicated in growing Class II patients who are
essentially mandibular deficient, with an average to flat
mandibular plane angle and upright lower anterior teeth over
the mandibular basal bone with minimal to moderate
crowding.

14. TWIN FORCE BITE CORRECTOR APPLIANCE
 The Twin Force bite corrector (TFBC) appliance is a hybrid fixed
push–type, semirigid FFA clamped to archwires in both the upper and
the lower arches bilaterally. Each unit is made up of two 15-mm
telescopic parallel cylinders. Within the cylinder is a nickel-titanium
(Ni-Ti) coil spring
that is activated when the
patient occludes.

15. TWIN FORCE BITE CORRECTOR APPLIANCE
 A plunger is incorporated at the end of each cylinder on both ends. At
the end of each plunger, hex nuts are present to attach the appliance
to the archwires mesial to the upper molars and distal to the lower
canine . At full compression a force of approximately 210 g is
delivered on each side by compression of the coil spring. This force is
synergistic to the indirectly applied force by the muscles of
mastication due to the forced anterior repositioning of the mandible

16. Twin Force Bite Corrector Class II Corrector

17. Twin Force Bite Corrector Class II Corrector

18. A unique feature of the TFBC appliance is
that since the point of force application is closer
to the C RES of the maxillary dentition,
compared to other traditional FFAs where the
point of force application in the maxillary arch
is distal to the upper molar , a lesser
clockwise moment is generated with the
appliance on the maxillary arch. Also, since the
appliance is clamped to the archwire, the
intrusive component of the spring force is
probably redistributed along the entire
denture base. In addition, since the force is
applied buccal to the C RES of the maxillary
molar, estimated to be at the center of the
trifurcation of the maxillary molar, a buccal
expansive force is experienced

19. Treatment Protocol
Pre-treatment records for a patient are obtained (Fig. 13-6) and
after the initial leveling and alignment phase, the arch wires are
progressively increased to 0.019 × 0.025-inch stainless steel in the
upper arch and 0.021 × 0.025-inch stainless steel in the lower arch
(Fig. 13-7, A–C). Both archwires are cinched to consolidate the
arches into a single unit to avoid any spaces developing or flaring
of the incisors

20. Pre-treatment records of Class II patient treated with the Twin Force bite
corrector (TFBC) appliance. A–C, Facial views. D–H, Intraoral views.

21.  Additionally, to minimize lower incisor flaring, MBT bracket
prescription with –6-degree torque lower anterior brackets is
advised. A 0.032-inch × 0.032-inch transpalatal arch is placed to
counteract the buccal forces exerted by the TFBC appliance.
 The standard TFBC version is attached by the hex nuts to the
archwires mesial to the maxillary molars and distal to the lower
canines, posturing the mandible forward in an anterior edge-to-
edge relationship

22. • After 3 to 4 months of appliance placement, the patient usually has an
overcorrected Class I molar and canine relationship.
• This helps to overcompensate for any relapse that may occur after
appliance removal (Fig. 13-7, G–I).

23. • Appropriate finishing and detailing is performed and the patient is
subsequently debonded (Fig. 13-8). The retention protocol involves a
fixed lingual retainer for the lower arch and a removable wrap-
around retainer for the upper arch.
• ( Post-treatment )

24. Effects of the TFBC Appliance (Skeletal)
 During the 3-month period of using the TFBC appliance In an
unpublished study a comparison was done between 20 subjects with
TFBC appliance and an untreated Class II sample,
 A point in the maxilla moved 0.5-mm posteriorly under the distal force
of the appliance and 1.7-mm inferiorly by the clockwise moment
acting on the upper arch (compared to 0.1-mm anterior and 0.4-mm
inferior movement in the control sample .
 The absolute length of the maxilla was similar in both groups
 The palatal plane rotated clockwise 0.5 degree in the TFBC sample
compared to 0.1 degree in the control sample. The mandibular
length (Ar-Pog) increased significantly—2.1-mm in the TFBC sample
compared to 0.7-mm in the control sample
 which could be attributed to a combination of growth and forward
posturing which could be attributed to a combination of growth and
forward posturing

25. Effects of the TFBC Appliance (Dentally)
 The upper incisors showed distal crown tipping of –7.0
degrees in the TFBC sample compared to 0.1 degree mesial
tipping in the control sample.
 The upper molar distalized –0.7-mm and intruded –1.1-mm
in the TFBC group; in the control group the upper molar
mesialized 0.3-mm and extruded 0.2-mm.
 The lower incisors flared 7.3 degrees
 and mesialized 2.6-mm in the TFBC group compared to no
movement in the control group.
 The lower molar mesialized 1.8-mm in the TFBC group
whereas in the control group the molar mesialized only 0.2-mm.
 Therefore the Class II correction was due to a combination of
skeletal and dental effects.

26. Treatment Timing with the TFBC Appliance
 The earlier studies with functional
appliances treated patients early for Class
II correction, more recent evidence
suggests that the optimum treatment timing
for removable functional appliances
appears to be during or slightly after the
onset of the pubertal peak in growth
velocity .
 The a study conducted on patients that
were divided into two groups: prepubertal
and postpubertal, based on skeletal
maturity at the beginning of treatment
 They concluded that the post pubertal
phase is the preferred phase for Class II
intervention with the TFBC appliance.

27. Case report 1
Patient Profile
The patient was a 12-year-old prepubertal male who presented with a
chief complaint of deep bite. He was diagnosed with a Class II
malocclusion due to a retrognathic mandible with full cusp Class II
molars bilaterally, 100% deep bite, and 6-mm of overjet

28. Treatment Progress
After initial leveling and alignment, stiff upper (0.019- inch × 0.025-inch
and lower 0.021-inch × 0.025-inch) stainless steel archwires were placed
with the TFBC appliance inserted with 5-mm of activation. Three months
later the patient was in a super Class I relationship and the appliance was
removed. Class II elastics were used to maintain the corrections and
finishing and detailing were done. The patient was debonded with
improvement of the soft tissue profile and good posterior occlusion

29. Retention Review
The patient was evaluated 6 years in retention and showed stable Class I
molar and canine relationship bilaterally (Fig. 13-26). Overall and
regional superimpositions (Fig. 13-27) showed that, in the treatment
phase, the upper molar was held in place with mesialization of the lower
molar. In the retention phase, both the upper and the lower molars were
very stable with negligible changes. The flaring of the lower anterior
teeth caused by the TFBC appliance was found to be stable in the
retention evaluation.

30. A, Pre-treatment lateral cephalogram. B, Post-treatment lateral
cephalogram. C, Lateral cephalogram in retention. D, Overall and
regional cephalometric superimpositions. Black is pre-treatment, red is
post-treatment, and green is retention.

31. CASE REPORT 2
Patient Profile
The patient was an 11-year-old prepubertal male in late mixed dentition
who presented with a chief complaint of crooked teeth. The patient was
diagnosed with a Class II malocclusion due to a retrognathic mandible
with end on molars bilaterally and minimal crowding in both the upper
and the lower arches. The patient had 5-mm of overjet and 50% deep bite

32. Treatment Progress
After initial leveling and alignment, the deciduous upper left second
molar was extracted and the second premolar was exposed and evaluated
to be small and rotated. Subsequently, stiff upper and
lower archwires were placed with the TFBC appliance for 3 months to
achieve the overcorrected super Class I molar and canine relationship.
The patient was debonded in good Class I molar and
canine relationship.

33. Retention Review
The patient was evaluated after 6 years and stable class I molar and
canine relationship was observed . However, mild relapse of the midline
diastema was noted. Overall and regional superimpositions showed that,
in the treatment phase, both the upper and the lower molars mesialized.
In the retention phase, there was no change in the position of the upper
and lower molars. There was significant flaring of the lower anteriors,
which was stable in the retention phase.

34. A, Pre-treatment lateral cephalogram. B, Post-treatment lateral
cephalogram. C, Lateral cephalogram in retention. D, Overall and
regional cephalometric superimpositions. Black is pre-treatment, red is
post-treatment, and green is retention.

35. CASE REPORT 3
Patient Profile
The patient was an 11-year-old female who presented with a chief
complaint of crowding . She was diagnosed with a Class II, Division I
malocclusion due to a prognathic maxilla and a retrognathic mandible
with Class II molars and canines on both sides and an overjet of 7-mm,
overbite of 70% with crossbite of the molars bilaterally, and a convex
soft tissue profile

36. Treatment Progress
The patient presented with a severe Class II skeletal relationship
with an ANB angle of 12 degrees . However, since the patient was still
growing, growth modulation was attempted. There was moderate
crowding in the upper arch and minimal crowding in the lower arch.

37. Treatment began with banding of the maxillary molars and rapid
maxillary expansion (RME) in the upper arch to create space for the
crowding. Subsequently, the patient’s upper and lower arches were set
up for TFBC appliance placement. The patient was debonded after 24
months of active treatment with a Class I molar and canine relationship
bilaterally

38. Retention Review
The patient was evaluated after 7 years and showed a harmonic soft
tissue profile with maintenance of stable buccal occlusion bilaterally
Overall and regional superimpositions showed mesial movement of both
the upper and the lower molars in the treatment phase and no changes in
the retention phase. Flaring of the lower anteriors was observed to be
stable in the retention phase.

39. A, Pre-treatment lateral cephalogram. B, Post-treatment lateral cephalogram. C,
Lateral cephalogram in retention. D, Overall and regional cephalometric
superimpositions. Black is pre-treatment, red is post-treatment, and green is
retention.

40. conclusion
Class II correction with the semirigid TFBC appliance
appears to be predominantly a combination of dentoalveolar
and mild skeletal changes. Long-term retention evaluation of
Class II correction achieved with the TFBC appliance
showed the correction to be stable. Dental effects of the
appliance, such as occlusal plane rotation, distalization, and
intrusion of the maxillary molars, appear to be transient
effects that do not contribute to overall Class II correction;
however, mesial movement and extrusion of the lower molar
with use of the appliance appear to be stable effects in the
long-term. Treatment efficiency based on overall treatment
time suggests that the postpubertal phase is the preferred
phase for Class II correction with the TFBC appliance.