The FR-2 appliance of Frankel and the Herbst appliance, two of the functional appliances that are often used in the correction of Class II malocclusion, are excellent examples of: (1) an appliance that is primarily tissue-borne and (2) one that is primarily tooth-borne,respectively The functional regulator (FR-2) was developed by Frankel for use during the mixed- and early permanent-dentition stages of development to produce changes in anteroposterior, transverse, and vertical jaw relationships in persons with Class II malocclusion. uses the buccal vestibule as a base of operation. The vestibular shields and the lower labial pads of the appliance are designed to restrain the musculature and remove forces that would otherwise restrict skeletal and dental development. The appliance provides a framework against which the craniofacial muscles function, in order to promote more normal patterns of muscle activity The stimulus for mandibular repositioning with a Frankel appliance is provided by the inferior border of the vestibular shield, the lower labial pads that touch the labial mucosa, and the lingual shield that touches the lingual mucosa. The pressure produced on the mucosa elicits a forward posturing of the mandible. The appliance usually is worn on a full-time basis for 18 to 24 months

1. A comparison of the Herbst and
Frankel appliances
in the treatment of Class II
malocclusion
ACHIEVED BY: Dr.Maen Dawodi

2. • The FR-2 appliance of Frankel and the Herbst appliance, two of the
functional appliances that are often used in the correction of Class II
malocclusion, are excellent examples of:
• (1) an appliance that is primarily tissue-borne and
• (2) one that is primarily tooth-borne,respectively.

3. The functional regulator of Frankel
• The functional regulator (FR-2) was
• developed by Frankel
• for use during the mixed- and early permanent-dentition stages of
development to produce changes in anteroposterior, transverse, and vertical
jaw relationships in persons with Class II malocclusion.

4. Frankel appliance
• uses the buccal vestibule as a base of operation.
• The vestibular shields and the lower labial pads of the appliance are
designed to restrain the musculature and remove forces that would
otherwise restrict skeletal and dental development.
• The appliance provides a framework against which the craniofacial
muscles function, in order to promote more normal patterns of muscle
activity

5. Frankel appliance
• The stimulus for mandibular repositioning with a Frankel appliance is
provided by the inferior border of the vestibular shield, the lower labial
pads that touch the labial mucosa, and the lingual shield that touches
the lingual mucosa.
• The pressure produced on the mucosa elicits a forward posturing of the
mandible.
• The appliance usually is worn on a full-time basis for 18 to 24 months.

6. Treatment effect of the FR-2
• The lateral expansion.
• Although no direct force is placed on the teeth to move them
laterally, 4 to 6 mm of increase in maxillary arch width and 2 to 4 mm
of increase in mandibular arch width are typically observed.
• This expansion may be due to the fact that the vestibular shields
inhibit the cheek muscles from acting against the occlusion and thus
allow for a greater role of the tongue in determining the lateral
positioning of the teeth.

7. Acrylic splint Herbst appliance
• The original type of banded Herbst appliance was introduced by
Herbst in the early 1900s. After achieving some initial popularity, the
Herbst bite-jumping mechanism fell into disuse until it was
reintroduced in the late 1970s by Pancherz.

8. Herbst appliance
• produces a forward repositioning of the mandible during function.
• This repositioning is achieved through the use of the Herbst bite-
jumping mechanism, a telescoping rod that extends from the region of
the upper first molar to the region of the lower first premolar. It is
usually attached to the teeth directly through the use of bands or
stainless steel crowns. Closure of the mandible can occur only in a
protruded position.

9. • the Herbst appliance was modified by replacing the original banded
design of Herbst with upper and lower acrylic splints that anchor the
bite-jumping mechanism.
• The maxillary acrylic splint can be removable or can be bonded in
place, particularly if a rapid palatal expansion appliance or anterior
brackets are connected to the splint.

10. • The mandibular splint is always removable. Because the appliance is
connected to the teeth, dentoalveolar treatment effects can be
expected to occur both anteroposteriorly and vertically (e.g., distal
movement of the upper posterior teeth, mesial movement of the
lower anterior teeth). In contrast to the FR-2 appliance, acrylic splints
allow no lateral movement of the teeth except when a rapid palatal
expansion appliance is used in conjunction with the splints.

11. MATERIALS AND METHODS
• Three samples were considered in this study. Records of patients who
had been treated with the functional regulator (FR-2) of Frankel were
compared with records of patients treated with the acrylic splint Herbst
appliance and also with records of uritreated children with Class II
malocclusion.

12. Groups studied and exclusion criteria
• Frankel sample. Records of approximately 150 patients who finished
Frankel therapy during a two-year period were submitted by eight
private practitioners.
• The application of the final exclusionary rule to the Frankel sample
reduced the size of the sample to 41 cases (22 girls and 19 boys). The
average age of the patients in the sample was 11 years 6 months at the
time of the initial film.

13. • Herbst sample. Cephalometric records of 138 patients treated with the
acrylic splint Herbst appliance were obtained from the private practices
of three of the investigators involved in this study.
• The application of these exclusionary rules eliminated 57 of the cases,
leaving 81 Herbst cases for consideration.

14. Control sample
• When the exclusionary rule was applied regarding the age of the subject
at the time of the initial film, a control sample of 21 cases (13 girls and 8
boys) was identified. The average age of this sample was 11 years 1
month at the time of the first observation.

15. Method of analysis
• The effect of functional appliance treatment on the growth of the
craniofacial region was determined by use of a conventional
cephalometric analysis that is an extension of that devised by
McNamara.
• Statistical methods:Scheffe's method of multiple comparisons was used
to determine differences among groups.

16. RESULTS
• Comparisons of starting forms
• Skeletal measures
• There were no statistically significant differences in starting forms with respect to any of the
17 horizontal or vertical skeletal measures in the treatment groups as compared with the
forms of the control group. However, there were some differences when the Herbst
treatment group was compared with the Frankel treatment group.
• Dentoalveolar measures
• There was no significant difference in any of the dental measures among the two treatment
groups and the control group. The only statistically significant difference was in the vertical
position of the upper first molar: the upper molar in the Herbst group was located in a
slightly more inferior position than in the Fr~inkel group.

17. • Overall comparison
• the 75 comparisons considered, only
7 of the variables showed any
statistically significant differences,
and several of the statistically
significant variables were measures
of the same anatomic relationships:
posterior facial height or the
anteroposterior position of the chin

18. Analysis of treatment effects
• The analysis of the effects of treatment used the same variables that
were used to compare starting forms. Because the interval between the
pretreatment and post treatment films varied among the three groups
analyzed, two types of data are presented.
• Table III shows the increments of growth for the three groups without
any adjustment for elapsed time between films.
• Table IV shows increments that have been annualized to provide a more
direct comparison of biologic activity

19. Although the annualized values for the Frankel and control groups were obviously less than
the actual values, the mean annualized increments (Table IV) for the Herbst patients
tended to be slightly greater than the corresponding actual increments (Table III). The
median duration for treatment of these patients was less than the mean of 1 year.

21. Maxillary skeletal relationships.
• four maxillary skeletal measures considered, there were no significant differences
between the Frankel treatment group and the controls. However, there was a
statistically significant difference in midfacial length increments when the Herbst
appliance group was compared with controls. Even greater differences were
observed when the Herbst group was compared with the Frankel group.
• Maxillary dentition
• The change in the horizontal position of the upper molar was measured by dropping
a line from the most posterosuperior point on the pterygomaxillary fissure
perpendicular to the Frankfort horizontal

23. Mandibular dental relationships.
• The average horizontal movement of the lower molar and lower incisor was
measured by drawing a line perpendicular to the mandibular plane through
pogonion. Measure merits were made from the mesial contact point of the
lower molar and the facial surface of the lower incisor to the constructed
pogonion perpendicular.
• Mandibular skeletal relationships.
• As measured from condylion to gnathion, mean mandibular length in the control
group increased an average of 2.1 mm/yr during the treatment period; in the
Herbst patients the measurement increased by 4.8 mm/yr and in the Frankel
patients, 4.3 mm/yr, values statistically significant with respect to the same
measurement from the controls.

24. Vertical dimension.
• Lower anterior facial height, as measured from anterior nasal spine to
menton, increased an average of 1 mm a year in the untreated Class II
sample.
• Lower anterior facial height increased an average of 2.2 mm in the
Frankel group and 1.8 mm in the Herbst group.
• Posterior facial height increases were also observed in the controls .No
significant differences were observed between either of the treatment
groups or the control group with regard to corpus length, sella-nasion
plane angle, palatal plane angle, or mandibular plane angle, the latter
three angles formed with the Frankfort horizontal.

26. DISCUSSION
• The results of this study suggest that both the acrylic-splint Herbst
appliance and the FR-2 appliance of Frankel produce skeletal and
dentoalveolar treatment effects on the growing craniofacial complex.
• These effects are not uniformly distributed but, rather, have specific
target areas, depending on the appliance used

27. • the Herbst appliance had a slight (0.5 mm) effect on the position to
point A. The movement of point A may be a reflection of the
spontaneous lingual tipping of the upper incisor that occurs during
Herbst appliance treatment.

28. • The Herbst appliance apparently prevented the vertical eruption of the
upper first molar by an average of almost 1 mm/yr (0.5 mm/yr versus
1.6 mm/yr in the other two groups).
• In addition, the average 1.4 mm/yr posterior movement of the upper
first molar observed in the Herbst appliance group was in contrast to the
average 1.3 mm/yr forward movement observed in the control group
and a 0.7 mm/yr forward movement observed in the Frankel group.

29. • A lingual tipping of the upper incisor was observed in both the
Frfinkel and Herbst appliance groups.
• the role of the upper labial wire of the Frankel appliance in producing
lingual tipping of the upper incisors is open to question.
• In contrast, more vertical eruption was observed on an annual basis
in the lower molar region among the Frankel group (1.7 mm) and the
Herbst group (1.3 mm) than in the control group (0.8 mm).

30. • Accelerated increments of mandibular length were observed in the
Herbst and Frankel groups. Whereas mandibular length in the control
group increased an average of 2. I mm on an annualized basis, in the
Herbst appliance group it increased an average of 4.8 mm, While in the
Frankel group it increased an average of 4.3 ram. However, this increase
in mandibular length was expressed more anteriorly in the Herbst group
(2.7 mm) than in the Frankel group (1.2 mm).

31. SUMMARY AND CONCLUSIONS
• This study demonstrated that both the Herbst appliance and the Frankel
appliance have measurable treatment effects in dental and skeletal
elements of the face. Both produced increases in mandibular length and
varying increases in lower anterior facial height. Greater dentoalveolar
effects were observed with the Herbst appliance than with the Frankel
appliance

32. •James A. McNamara, Jr., DDS, PhD,* Raymond P.
Howe, DDS, MS,** and
Terry G. Dischinger, DDS***
Ann Arbor, Mich

33. THANK YOU