| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Orthodontics, Sunderland Royal Hospital, Kayll Road, Sunderland SR4 7TP, UK
Department of Orthodontics, Newcastle Dental Hospital, Richardson Road, Newcastle, UK
Department of Orthodontics, Dumfries Royal Infirmary, Bankend Road, Dumfries, UK
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
This was a retrospective study involving analyses of pre- and post-treament cephalograms of 63 Class II division 1 patients treated with the FR to demonstrate the relative maxillary, manidibular, incisor, and molar movements during treatment compared with normal growth within a control group of untreated 39 Class II division 1 cases drawn from the same demographic population.
All cephalograms were digitized and subjected to a Pitchfork analysis, which measured invididual anteroposterior skeletal and dental changes during the period of study.
It was shown that the FR was effective in treating Class II division 1 cases with the studied group being corrected to a clinically acceptable overjet and overbite of 2-3 mm. The majority of the correction came from dental movements, the most significant being the retroclination of the upper incisor teeth (mean 4.1mm, 95 per cent CI ±0.44) and proclination of the lowers (mean 2.2 mm 95 per cent CI ± 0.57). As regards skeletal correction, the most significant contribution was the restraint of normal maxillary forward growth (mean -0.2mm, 95 per cent CI ± 0.62) with forward manidiblar growth not being a significant factor.
Key words: Class II division 1, Frankel, Functional Regulator, Pitchfork Analysis
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
;
Teuscher, 1978;
Eirow, 1981;
Bimler, 1983;
Clark, 1988).
The Functional Regulator FR was developed by Dr Rolf Frankel of Zwickau, East Germany, as
an alternative to the activator-type appliances
(Frankel, 1966).
Frankel believed that poor postural behaviour and
activity of the orofacial musculature was the primary aetiological factor in producing a
malocclusion. He felt that if the abnormal musculature could be altered, then so surely would the
dentition be released from its influence and allow normal development to take place. As the
name implies, the actions of the FR are intended to change or regulate the muscular environment
of the face and teeth,
to stretch facial musculature to normal dimensions, impede abnormal activity of the lips, tongue,
and cheeks, and thus allow
development of the jaws and teeth in all three planes
(Frankel,1980).
Little doubt exists that the FR is an effective method of treatment for Class II division 1
malocclusions, but there is considerable uncertainty regarding the mechanism of the correction. It
has been claimed that the FR promotes forward growth of the mandible
(Frankel,1966;
McNamara, 1982a,
b,
c )
and restriction of the maxilla
(Owen, 1983a,
b,
c),
while others claim that the effects are purely dentoalveolar with little or no skeletal effects
(Gianelly et al., 1983;
Righellis, 1983).
The majority of researchers agree that there is retroclination of the upper incisor teeth during
treatment
(Schulhof and Engel, 1982;
Creekmore and Radney, 1983;
Robertson, 1983),
as well as
agreeing that proclination of the lower incisors is a common finding, although it is maintained
that this is an effect of a poorly constructed and handled appliance
(Eirow, 1981;
Frankel, 1984).
There is no consensus of opinion on how the molar teeth behave
in moving mesiodistally with some researchers finding restriction of the upper molars and mesial
movement of the lowers
(Schulhof and Engel, 1982;
Creekmore and Radney, 1983),
other findings refuting this
(Frankel, 1969a,
Hamilton et al., 1987).
In a review of the literature
Bishara and Ziaja (1989)
suggest that 60-70 per cent of
Class II correction is orthodontic tooth movement, only 30-40 per cent orthopaedic. This purpose
of this study was to assess the relative contributions of skeletal and dental components in
correction of Class II division 1 malocclusions when treated with the FR.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
The records of 115 consecutive Class II division 1 cases treated between 1989 and 1992 with the Functional Regulator of Frankel were examined. All patients were of Caucasian origin.
Standardized cephalometric radiographs had been taken using a Siemens Orthophos-C cephalostat with settings of 14 mA, and between 73 and 77 kV. Exposure times varied between 0.5 and 0.63 seconds. The film used was either Kodak TMG-RA1 or DuPont Ultravision G, with a developing time of 90 seconds using a Kodak N35 developer.
To be included the following criteria had to be met:
),
with an overjet greater than or equal to 6 mm. The records from 52 originally selected cases were discarded for the following reasons:
This left a sample of 63 treated cases, 42 girls and 21 boys in the study. For the purposes of comparison, records were obtained from 58 untreated Class II division 1 subjects, 19 boys and 39 girls, from the same demographic population.
Criteria for inclusion was the same as for the treated patients except that no treatment at all was carried out. Patients within this group had either been offered orthodontic treatment and declined, or had been deemed unsuitable for orthodontic treatment.
Exclusion criteria of poorly defined cephalometric landmarks and if any patient had had any dental extractions for any reason during the period between radiographs were applied. This resulted in the exclusion of 19 cases, leaving 39 cases, 14 boys and 25 girls, as the studied control group.
The appliance design was to the FR specification as de- scribed by
McNamara and Huge (1983)
with only one slight modification that being the lingual acrylic pad, originally
recommended by Frankel, replaced by a connecting wire as this was found to be better tolerated
by patients.
The use of the FR had been discontinued when the overjet and overbite was reduced to 2-3 mm, when the patient was either deemed to have finished active treatment or went on to further appliance therapy.
The pitchfork analysis used in this study is designed to measure the individual antero-posterior
dental and skeletal changes that contribute to the correction of a Class II malocclusion. This
analysis has been described in detail by
Johnston (1986),
(1996).
It uses the method of superimposing a later radiograph on an earlier one to measure the physical movement of the upper and lower buccal segments, and incisors relative to their dental bases, both bodily and angular movements, as well as the displacement of the maxilla and mandible relative to the cranial base. The individual components of change are all designated positive or negative appropriate to its impact on treatment: positive if it would help to correct a Class II malocclusion, and negative if it tends to move the skeletal or dental relationship further towards Class II.
The algebraic sum of the various components will equal the change in the molar relationship and overjet. This analysis cannot only measure the magnitude of changes during treatment, but also the source of the changes, dental or skeletal.
The pitchfork diagram is generated to show a summary of the various components of change that come together at the occlusal plane (Figure 1).
|
),
both films from each patient were
traced at the same time with the films side by side on the viewer to try and minimize errors in
locating cephalometric landmarks. In order to execute the analysis used, the following structures
were traced:
For the execution of the analysis, the tracing of the later cephalogram was laid on top of the
earlier and the maxillae superimposed by orientating on the palatal plane ANS- PNS, and
registering on the palatal trabeculae and lingual palatal curvature as described by
Johnston (1986).
Care was taken to ensure that the PTMF of the later film lay at or posterior
to the PTMF of the earlier. In order to ensure future accurate re-superimposition if necessary,
three registration crosses were marked on the first film and transferred to the later film once the
maxillary registration had been established.
The superimposed films were stabilized on a GTCO digitizing pad and the points individually digitized in sequence using a GTCO digitizer linked to a Compaq Prolinea 4/335 computer, which executed the analysis from a program specially written for the purposes of producing a pitchfork diagram, using GeLa 1.7, a computer language designed for writing programs to analyse cephalograms. The data was stored on floppy disc and later used to generate pitchfork diagrams using a Hewlett Packard HP560 printer.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
|
It should be remembered that when analysing a pitchfork diagram and values, that positive values are those contributing to correction of the Class II malocclusion and negative values are non-contributory or antagonistic.
The results for all measurements are shown in Table 2.
|
Mandibular changes
The mean change of the mandible was seen to increase in both the treated (4.1 mm) and control
(5.0 mm) groups, the small difference between the two not being statistically significant. The
amount of movement in the treated group ranged from 12.8 mm of advancement to -1.4
mm of
relative backward movement. The maximum change in the controls was greater than the treated
group at 14.8 mm, the minimum value being -0.2 mm.
ABCH changes
ABCH, the anteroposterior change in the relationship between the maxilla and mandible, made a
mean positive contribution in both the treated (4.0 mm, range 0-8.9 mm) and control (1.9 mm,
range -2.0 to 4.7 mm) groups. The difference between the two groups (2.1 mm) was
statistically
significant (P < 0.001).
All skeletal changes are shown in Figure 2.
|
With regard to the lower molar, there was a significant difference between the total amount of movement in the treated group (mean 0.9 mm) and the control group (-0.6 mm). The net correction of the position of the lower molar in the FR group was due to the bodily movement (1.6 mm), the mean tip (-0.7 mm) opposing the Class II correction. In the FR group a mean total molar correction of 3.8 mm was calculated, the same calculation being only 0.2 mm in the control group. The correction seen in the FR group, however, was due to the ABCH change, the relative movement of the molars being -0.2 mm not contributing to buccal segment correction at all and, in fact, being slightly antagonistic. The minimal overall mean change seen in the control group (0.2 mm) is a good example of dentoalveolar compensation, the molar relationship change (-1.7 mm) maintaining the buccal segment relationship in the face of relatively favourable skeletal growth (ABCH change of 1.9 mm).
Incisor change
The greatest movement of the incisors in the treated group was their tip, 4.1 mm of retroclination
in the upper incisors, 2.2 mm of proclination in the lower. The range of retroclination of the
upper incisors was from -1.0 to 8.2 mm, the tip of the lowers ranging from a proclination
of 7.3
mm to a retroclination of -9.3 mm.
This last figure was somewhat aberrant and was probably due to an error in the method, the
likelihood of so much retroclination occurring with FR treatment being very low indeed.
Bodily movement of the upper incisors ranged from -4.9 to 3.7 mm with a mean movement of -0.9 mm (forward direction). These figures give a correction value of 3.2 mm for the total upper incisor movement and 1.4 mm for the lower incisors, both being seen to contribute favourably to the correction of the Class II malocclusion.
The mean movement of the control incisors was -0.8 mm, the components both being antagonistic to correction of the overjet, being -0.6 and -0.2 mm for tip and bodily movement, respectively. The lower incisor movement was again slightly antagonistic, with a mean tip of -0.6 mm and bodily movement of -0.5 mm, adding up to a total movement of -1.1 mm.
The change in overjet is the total change in incisor relationship and is the algebraic sum of ABCH + Total U1 + Total L1. This works out at 8.7 mm for the treated group, the ABCH contributing a little under half this correction. The control group's overjet reduction was a mean 0 mm demonstrating no change in the incisor relationship. This difference between the two groups was highly significant (P < 0.001).
The changes in molar and incisor positions are shown in Figure 3.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
)
seems to suggest that 9.4 years is the
optimum age for any functional appliance treatment, he agrees with
Tanner (1951)
that growth spurts are very variable and that variation between individuals are very common. The
range in this study of 9.2-11.9 years is seen to be representative of patients being treated at the
optimum age around the pubertal growth spurt.
The treatment time ranged from 10 to 23 months, with a mean length of 16.4 months. When
compared with other studies this seems to be slightly shorter than average,
McNamara et al. (1990)
studying over 18 months,
Schulhof and Engel (1982)
over 21 months, and
Creekmore and Radney (1983)
over 29 months, however,
variation in response to treatment with the FR has to be considered. One of the main determining
factors in the length of treatment time is the co-operation and compliance of the
patient—if the appliance is not worn full time, then the treatment time is obviously
increased. The growth in the untreated control group was studied over a similar period (mean
17.3 months, range 11-23 months) and matched well the starting age of the FR group.
Skeletal changes
The way in which the FR is held in the mouth when the mandible is postured forwards places a
reciprocal force acting distally on the maxilla. The theory is that the normal forward growth of
the maxilla is inhibited or even reversed to effect distal movement of the maxilla relative to the
cranial base, a situation which
Hotz (1970)
said would be ideal for correction of a
Class II skeletal discrepancy.
In this study the mean movement of the maxilla was -0.2 mm, which in terms of the
pitchfork
analysis represents a very small increment of forward growth in an anteroposterior direction in
spite of the forces redirected via the FR. The equivalent result in the control group of -3.1
mm
represents the normal mean maxillary growth relative to the cranial base. As would be expected
all the control cases demonstrated negative values for Max., this representing normal forward
growth of the maxilla range -1.1 to -10.2 mm. That the FR is unable reliably to
fully restrain
forward maxillary growth is evident from the most unfavourable value recorded of -7.1
mm. and
the fact that 32 out of the 63 FR cases demonstrated a negative result. The most favourable value
of 5.8 mm on the other hand represents a significant restraint and probably distal movement of
the maxilla. These findings agree with some authors,
Owen (1981,
1983a,
b,
c),
Neilson (1984),
and Creekmore and Radney (1983)
all
finding some degree of decrease in forward growth taking place. The difference between the
mean maxillary movement of the two groups was a highly statistically significant factor and
suggests that a good deal of the Class II skeletal correction was restraint of the maxilla.
Whether or not there is an increase in size or acceleration of growth of the mandible is one of the
major controversies in functional appliance therapy. Although many researchers have claimed
that the FR causes extra mandibular growth
(Righellis, 1983;
McNamara et al., 1985),
this study showed that there were no significant differences
between the FR and control groups as far as mandibular movement is concerned, the mean FR
movement being 4.1 mm, standard deviation 3.0 mm; the control 5.0 mm, and standard
deviation 2.6 mm. As the 5.0-mm change in the control was due to normal growth, it can be
assumed that the 4.1-mm change in the FR group was no more than normal growth rather than
any effect of the appliance. The maximum value seen in the control was 14.2 mm and for the FR
it was 12.8 mm; again, because this change in the controls was due to normal growth it must be
assumed that even the maximum FR change was no more than normal growth change. That the
size of the mandible is unaffected with the FR is supported by evidence from
Creekmore and Radney (1983),
and Hamilton et al. (1987),
who found no
significant differences between FR and untreated patient groups.
Negative values seen both in the FR and control groups at first seem difficult to explain, after all,
the mandible cannot reduce its size. However, it should be remembered that only anteroposterior
movements are measured and no amounts of movements in other directions are accounted for.
Rotation of the mandible during growth has previously been reported
(Bjork and Skieller, 1983),
which probably accounts for the negative values seen. A backwards rotation
would worsen a Class II skeletal pattern and, if subjected to a pitchfork analysis, generate a
negative value if it exceeds forward growth. Because a backwards pattern of growth rotation is a
common finding in Class II discrepancies, one of the aims of FR treatment is to encourage a
forward rotation during growth
(Isaacson et al., 1977;
Harvold and Vagervik 1971).
That the FR group demonstrated slightly more negative values
than the controls suggests that this aim of FR treatment is unsuccessful.
The ABCH values represent the maxillo-mandibular differential, the movement of the mandible relative to the maxilla. A positive value means that the mandible has outgrown the maxilla, negative values the maxilla outgrowing the mandible. In the FR group where the mean was 4.0 mm in an anteroposterior direction, no negative values were seen, the minimum value of 0 mm being a situation where the forward movement of the mandible matched that of the maxilla, otherwise, in all instances, the mandible came forward further than the maxilla. It would be expected that in the control group, the mean ABCH to be close to 0 mm, with both jaws growing at the same rate, but the mean value was 1.9 mm with a standard deviation of 1.5 mm and a range of -2.0 to 4.7 mm. In fact, only three patients out of the total control group demonstrated a negative ABCH value, and only two out of 39 had a value within 0.5 or 0 mm. This finding perhaps suggests that there is a differential in growth between the maxilla and mandible, the mandible showing greater anteroposterior movement.
Dental changes
Although tissue-borne, it is widely accepted that the FR causes a significant amount of dental
movements within the dental bases. The ideal situation for the correction of the buccal segment
relationship would be the mesial movement of the lower molars and distal movement of the
uppers, or the restraint of the latter as the maxilla comes forward.
Frankel (1969a,
b)
stated that there was no movement of the molars in these directions, a statement that has not
proved to be valid in the light of further studies. In this study, the upper molars were seen to
move mesially with a mean total movement of -1.1 mm. When this is compared to the
movement
of the maxilla -0.2 mm it would appear that the upper molars have come forward further
than the
maxilla and that the FR has been fairly ineffective at preventing this. The mean total lower
movement of 0.9 mm, being positive, was in a contributory direction, albeit a very small
contribution, although when added to the mandibular movement a total forward movement of 5.0
mm was seen to occur.
When comparisons are made with the controls' molar movements, the uppers came forward by the same amount (-1.1 mm), but the lower molars were not seen to come forward, at -0.6 mm total change a statistically significant difference from the FR group.
Johnston (1986)
suggested that the FR may act as a bite plane disrupting normal
intercuspation, thus allowing free movement of the molars. His findings were that the maxillary
molars were held static with mesial drift of the lower molars. He did not find, however, that
dental (molar) movements are the most significant factor in correction of the Class II
malocclusion
and certainly the results from this study seem to agree with this. Regarding the lower molars, the
results of this study agree with most researchers, suggesting that while there is slight mesial
movement of the lower molar, the majority of its movement is due to the forward movement of
its dental base
(Hamilton et al., 1987);
McNamara et al., 1990).
The figure generated for the total molar movement is the sum of the movements of the upper and lower molars with the ABCH change. With reference to the results of skeletal movement, it can be seen that the mean 3.8 mm of correction seen in the FR group is largely due to the mandible outgrowing the maxilla rather than significant dental movements (the -1.1 mm upper and 0.9 mm lower molar movements all but cancelling each other out) and within that differential, the maxillary restraint being the significant factor. The change in the control group was 0.2 mm, which is very close to what would be expected, which would be no change in molar relationships—dentoalveolar compensation appears to have kept the buccal segment relationship fairly static in the light of the mandible outgrowing the maxilla on average.
It is a wide held consensus of opinion that the FR causes proclination of the lower incisors and
retroclination of the uppers
(McNamara, 1985).
This was again shown to be the
case in this study, the upper incisors being retroclined on average 4.1 mm, the lowers proclining
a mean 2.2 mm. It may also be expected that the teeth would have moved bodily in similar
directions, but this was not seen to be the case (-0.9 mm U1 bodily, -0.8 mm L1
bodily), giving
the total U1 movement of 3.2 mm and the lower 1.4 mm, both positive values and thus
contributing to the Class II correction. Commonly, the overjets seen in patients treated with the
functional appliances are greater than 6 mm and further correction in addition to this net incisor
movement
would be necessary by other means. In the case of this study, the maxillo-mandibular differential
of 4.0 mm made up this further correction.
The figures from the control group showed on average no incisor movement aiding a Class II correction and, in fact, the movements, being negative, made the situation slightly worse (total U1 -0.8 mm, total L1 -1.1 mm ), although the range was variable. It may be expected that the incisor teeth would have the same dentoalveolar compensatory effect that the Class II molars were shown to have. In fact, when the total incisor change was added to the skeletal change, the difference was seen to be 0 mm with a standard deviation of 1.1 mm and a close range of -2.4 to 2.3 mm. This result would seem to satisfy the belief that the Class II malocclusion will stay much the same in the absence of any orthodontic treatment, dentoalveolar movements maintaining the dental discrepancy even in the face of antagonistic movements.
By comparison the average total overjet difference in the treated group was 8.7 mm, which was a
highly significant difference from the controls. This correction was the combination of ABCH
and the total incisor movements. Because the mandible has already been seen not to come
forward in the FR group more than would be expected in normal growth, it is the anterior
movement of the lower incisor, which is the contribution in the lower arch to correction of the
Class II malocclusion. In the upper arch, the movement of the upper incisor and restraint of the
maxilla are both important factors in Class II correction, and combine to be the most significant
treatment change with the FR. It seems reasonable to look at the Class II correction in terms of
incisor relationship, as it is based on the incisor relationship that the British Standards Institute
define a Class II division 1 malocclusion, and also that an incisor discrepancy is usually the cause
of the patients' initial complaint.
Creekmore and Radney (1983)
reported
that in their study the correction of a Class II division 1 malocclusion with a FR, 37 per cent was
due to upper incisor retroclination and 26 per cent labial movement of the lower incisors. In the
present study, the same percentage contribution was seen regarding the upper incisors 37 per
cent, but only 17 per cent of the amount was due to lower incisor movement.
It can be seen that the major effect on the correction of the malocclusion was the incisor
movement, contributing to 54 per cent of the total overjet correction, the rest being due to an
orthopaedic effect of the appliance, proportions which are similar to those reported elsewhere
(Bishara and Ziaja, 1989).
|
Conclusions |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsReferences |
|---|
Bishara, S. E. and Ziaja, R. R. (1989) Functional appliances: a review,American Journal of Orthodontics , 95 , 250 –258.
Bjork, A. and Skieller, V. (1983)European Journal of Orthodontics
, 5
,1
–46.
British Standards Institution (1983) BS4492, British Standard Glossary of Terms Relating to Dentistry, British Standards Institution, London.
Clark, W. J. (1988) The twin block technique,American Journal of Orthodontics , 93 , 1 –18.
Cohen, A. M. (1980) The timing of orthodontic treatment in relation to growth,British Journal of Orthodontics , 7 , 69 –74.[Medline]
Creekmore, T. D. and Radney, L. J. (1983) Frankel appliance therapy: orthopaedic or orthodontic?American Journal of Orthodontics , 83 , 89 –108.[Medline]
Eirow, H. L. (1981) The Bionator,British Journal of Orthodontics , 8 , 33 –36.[Medline]
Frankel, R. (1966) The theoretical concept underlying the treatment with functional correctors, Transactions of the European Orthodontics Society, pp. 223-250.
Frankel, R. (1969a) The treatment of Class II Division 1 malocclusion with functional correctors,American Journal of Orthodontics , 55 , 265 –275.[Medline]
Frankel, R. (1969b) The functional matrix and its practical importance in orthodontics, Transactions of the European Orthodontics Society, pp. 207-218.
Frankel, R. (1980) A functional approach to orofacial orthopaedics,British Journal of Orthodontics , 7 , 41 –51.[Medline]
Frankel, R. (1984) Concerning recent articles on Frankel appliance therapy,American Journal of Orthodontics , 85 , 441 –445.[Medline]
Gianelly, A. A., Brosnan, P., Martignoni, M. and Bernstein, L. (1983) Mandibular growth, condyle position and Frankel appliance therapy,Angle Orthodontist , 53 , 131 –142.[Medline]
Hamilton, S. D., Sinclair, P. M. and Hamilton, R. H. (1987) A cephalometric, tomographic and dental cast evaluation of Frankel therapy,American Journal of Orthodontics , 92 , 427 –434.
Harvold, E. P. and Vagervik, K. (1971) Morphogenic response to activator treatment,American Journal of Orthodontics , 60 , 468 –490.
Hotz, R. (1970) Application and appliance manipulation of functional forces,American Journal of Orthodontics ,58 , 459 –478.[Medline]
Isaacson, R., Zapfel, R., Worms, F., Bevis, R. and Speidel, T. (1977) Some effects of mandibular growth on the occlusion and profile,Angle Orthodontist , 47 , 97 –106.[Medline]
Johnston, L. E. (1986) A comparative analysis of Class II treatments, In: Vig, P. S. and Ribbens, K. A. (eds), Science and Clinical Judgement in Orthodontics, Monograph 19, Craniofacial Growth series, Centre for Human Growth and Development, University of Michigan, Ann Arbor, pp. 103-148.
Johnston, L. E. (1996) Balancing the books on orthodontic treatment. An integrated analysis of change,British Journal of Orthodontics , 23 , 93 –102.[Abstract]
McNamara, J. A. (1982 a) On the Frankel appliance. Part 1. Biological basis and appliance design,Journal of Clinical Orthodontics , 16 , 320 –337.
McNamara, J. A. (1982b) On the Frankel appliance. Part 2. Clinical management,Journal of Clinical Orthodontics , 16 , 390 –406.
McNamara, J. A. (1982c) The Frankel appliance: biological basis and appliance design,Journal of Clinical Orthodontics ,16 , 320 –337.
McNamara, J. A. and Huge, S. A. (1981) The Frankel appliance (FR-2) model preparation and appliance construction,American Journal of Orthodontics , 80 , 478 –495.[Medline]
McNamara, J. A., Bookstein, F. L. and Shaughnessy, T. G. (1985) Skeletal and dental changes following function regulator therapy in Class II patients,American Journal of Orthodontics , 88 , 91 –110.[Medline]
McNamara, J. A., Howe, R. P. and Dischinger, T. G. (1990) A comparison of the Herbst and Frankel appliances in the treatment of Class II malocclusion,American Journal of Orthodontics , 89 , 134 –144.
Owen, A. H. (1981) Morphologic changes in the sagittal dimension using the Frankel appliance,American Journal of Orthodontics , 80 , 573 –603.[Medline]
Owen, A. H. (1983a) Clinical application of the Frankel appliance: case reports,Angle Orthodontist , 53 , 29 –88.[Medline]
Owen, A. H. (1983b) Clinical management of the Frankel FR-2 appliance,Journal of Clinical Orthodontics , 18 , 605 –618.
Owen, A. H. (1983c) Morphological changes in the transverse dimension using the Frankel appliance,American Journal of Orthodontics , 83 , 200 –217.[Medline]
Righellis, E. G. (1983) Treatment effects of Frankel, activator and extra-oral traction appliances,Angle Orthodontist , 53 , 107 –121.[Medline]
Robertson, N. R. E. (1983) An examination of treatment changes in children treated with the functional regulator of Frankel,American Journal of Orthodontics , 83 , 299 –310.[Medline]
Schmuth, G. P. F. (1983) Milestones in the development and practical application of functional appliances,American Journal of Orthodontics , 84 , 48 –53.[Medline]
Schulhof, R. J. and Engel, G. A. (1982) Results of Class II functional appliance treatment,Journal of Clinical Orthodontics , 16 , 587 –599.
Teuscher, U. (1978) A growth related concept for skeletal Class II treatment,American Journal of Orthodontics , 74 , 258 –275.[Medline]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
