American Journal of ORTHODONTICS Volume
71, Number
1, January,
ORIGINAL
1977
ARTICLES
The differential force method of orthodontic treatment P. R. Begg,
D.D.Sc., L.D.S., B.D.Sc., and Peter C. Kesling,
Adelaide, South Australia,
Many
D.D.S.
and Westville, Ind.
wish to learn but few the price will pay. 3uveua1, first century A.D.
T
his essay is being written to explain the light wire differential force technique free of unnecessary and incorrect variations. It is hoped that this will help eliminate the confusion that has been caused by several published accounts which, while purporting to describe this treatment, actually are misleading because they contain retrogressive alterations. Some orthodontists now employing this technique have received only practical training in the manipulation of the appliances and very little teaching on its theoretic basis. Therefore, a brief description of Stone Age man’s attritional occlusion, the basis upon which this method was developed, is also included. Unless this section is carefully studied, the part describing appliance therapy will be of little value to those using this method to treat patients. This essay is an abridged and revised version of two lectures delivered at the fortyfifth annual meeting of the Great Lakes Society of Orthodontists, Oct. 5 to 9, 1974. We wish to thank all members of the Kesling and Rocke Group of Westville, Ind. Without their illustrations and records of appliance therapy throughout treatment, this essay would not achieve its purpose.
Also, to dissuade orthodontists from attempting to employ edgewise brackets in conjunction with this technique, a brief analysis of root-moving forces delivered by the edgewise appliance is included. In the hope of holding the attention of the more clinically oriented orthodontists and of making this article less dreary, the records of treated cases and recent improvements in this method will be interspersed throughout its entirety. 1
Am. J. Orthod. January 1977
Fig.
1. Tree gtment
the
extent
to (the
t he
size
of of
with the
and lower upper left fir st permanent
havi e previc susiy
the
protrusion
been
Begg of
jaws,
the
the right
severest and
molars) published
differential anterior left were in the
force teeth
condition first
1961,
of
I (P.
premolars
extracted July,
method.
and
prior issue
This
excess R.
Begg) also
to
appliance this
the
tooth have
and of
is, from of the
Sitandpc
subsi &a rice treatec
Eight
upper
anI d lower
therapy.
( TI7ese
JOURNAL.)
hint of re lative teeth right rc tcords
Differential
force method
3
Fig. 2. A, Molar band with buccal tube (0.036 inch inner diameter and 0.250 inch long, 0.914 mm. I.D. and 0.635 mm. long) and intermaxillary hook attached to buccal surface. Note that tube is positioned near the gingival band margin, to help prevent the arch wire from being distorted from occlusal forces. A ball-ended hook is also attached to the lingual surface of each molar band to accept elastics or ligature ties, if necessary. 6, Modified ribbon arch bracket (TP 256-500) especially designed for light wire technique, prewelded to a preformed band. Will accept 0.016 inch (0.406 mm.) arch wires in Stage 1, and 0.018 or 0.020 inch (0.457 or 0.508 mm.) wires in Stages 2 and 3. Permits free crown tipping or controlled root torque when required.
The treatment of a severe malocclusion is shown in Fig. 1. This patient’s teeth were so large, compared with the space available in her jaws, that eight teeth (the four first premolars and the four first permanent molars) had to be extracted prior to appliance therapy. Very few patients (2 to 3 per cent) have such severe malocclusions as to require the pretreatment ext,raction of these eight teeth. Development
of the
light
wire
differential
force
technique
Early variations of the edgewise technique. This method would not have been developed if one of us (P. R. Begg) had not been taught by Dr. Edward H. Angle in 1924-25 to use the edgewise appliance. We owe him a debt beyond repayment. However, in contrast to the original nonextraction method of using the edgewise mechanism as taught by Dr. Angle, I (P. R. Begg) began to extract teeth prior to treatment, when necessary. This decision was made as a result of studying Stone Age Australian aboriginal and other dentitions in relation to the etiology of malocclusion. In 1928 Australian orthodontists were shown the results of treatment with the edgewise mechanism after extraction of the four first premolars in those patients who inherited teeth too large for their jaws. The only change made at that time in Dr. Angle’s edgewise mechanism was the use of large round buccal molar tubes instead of rectangular tubes. These round tubes have evolved into the smaller buccal tubes that we now employ in conjunction with the modified ribbon arch brackets (Fig. 2). This change was made so that frictional binding of arch wires would not prevent horizontal elastics from closing extraction spaces. Also, many of these patients had to wear headgear. These orthodontists were, with the exception of Dr. Stanley Wilkinson, noncommittal concerning these treatment results. They were surprised by the unorthodoxy of pretreatment tooth extractions. From 1928 until the present day tooth extraction has continued to be used as an adjunct to orthodontic treatment whenever this appears to be necessary. It was recognition of the fact that the lifelong hereditary forces of mesial migration and continual eruption are very light that led to the discarding of the
Am. J. Orthod. Januarf~ 1977
Fig. 3A.
Facial
photographs
years
at the
beginning
old
before of nonextraction
(top)
and
after
treatment,
treatment which
(bottom]. lasted
Patient
was
12
13 months.
edgewise treatment method. This change was made in order to simulate Nature by employing light continuous orthodontic force values instead of the heavy intermittent forces used in the edgewise technique. A metallurgist, Arthur .J. Wilcock of Victoria, Australia, was able, after years of experimentation, to produce arch wire material suitable for the technique. The fact that the lighter force values employed cause less loosening of teeth, less discomfort, and less damage to roots and tooth-invcst,ing tissues is evidence that these forces arc optimal for tissue tolerance. The records of a patient treated with this technique, using these light force values and directly bonded brackets, are shown in Fig. 3. Those orthodontists who use this method properly, and who formerly used the edgewise technique, report that their average treatment time is much less than that previously required. Furthermore, it now takes only one third to one fourth the chair time for each patient. This technique and orthodontic ccphalomrtrics were developed concurrently, but independently of one another. Most anthropologists and biomctricians con sider that it is impossible to locate landmarks accurately on lateral cephalometric head films. For this and other reasons, we hare never felt secure in following any of these concepts in the planning of our patients’ treatment.
Fig.
3, B to
that
this
the
end
of
anterior ments
are seen
a tooth
3,
edge
to
to
on help
views plus
profile,
on worn
the
six
molar upper
of upper
a tooth
of the
dental
teeth
the
positioner
of
for
indicated
C, Occlusion
nonextraction
at
cases).
I. Direct
D, Final
bonded
occlusion.
in nonextraction
before dental
decision end
teeth.
of teeth.
5
Note attach-
Stage
cases.
The
3 was patient
results.
arches
at the
anterior
Diagnosis
treatment.
is Class teeth.
situation
treatment
to
extraction
relationship the
force method
in most
anterior
location to
the
simultaneously
six retain
prior
without
and the
led
F, Alignment
mass. had
arch
soft-tissue
occur
as is normally
positioner
upper
treated
edge,
in place
(5 months),
the
2 malocclusion
2 (which
in
attachments patient
Division
E to G. E, Occlusal
as the
of tooth
II,
be successfully
1 and
be short
spaces well
could
teeth
relatively
Fig.
B, Class
Stages
can
wore
D.
patient
Diferentinl
to of
G,
3 months.
treatment. arches
treat
Stages Arch
form
this 1 and and
The
presence
relative
to
patient
without
2.
Note
tooth
the
of
basal
slight
bone,
as
a reduction direct
alignment
bonded after
the
Am. J. O?%hod. January 1977
:‘li
b
Fig. 3H. a and b, Molded polycarbonate bracket and special lock pin of the type used in the treatment of this patient. c, Small stainless steel mesh pad which, when spot-welded to the base of the metal bracket permits it to be bonded directly to the tooth surface.
Treatment procedures must be based on knowledge gained from studying the occlusion of Stone Age man. Of primary concern is the difference between unworn and attritional tooth mass, together with the realization that everyone has his own hereditary rate of continual mesial migration and vertical eruption of the teeth. Treatment planning is made with these concepts in mind. This propdure is more accurate than depending upon static, two-dimensional cephalometrics. The lack of attrition in the presence of mesial migration and continual eruption indicates the need for reduction of tooth mass in most patients. Recognition,
use,
and
teaching
of the
technique
It is fortunate that, 18 years ago, I)r. H. I). Kesling and I)r. (George Dinham visited my (I’. R. Begg’s) office in Adelaide, observed differential force treatment, and were impressed with it. They also seemed, in this short time, to get the message about attritional occlusion, mesial migration, and the continual eruption of teeth. It was also fortunate that they had the foresight and determination to go back to their homes in the United States and, in spite of many disappointments, to persevere with the differential force trcat,ment, using the proper appliances. They not only used the differential forcr light wire treatment method themselves, but Dr. H. I). Kesling instilled into his partners in the Orthodontic Group at Westville, Indiana, the urge and determination to use this method from that time on. By the time they had completed their first 100 cases with this technique, the Orthodontic Center at Westville was completed. Two hundred fifty men were invited and attended t,hree different showings of this work. From these showings, there developed a demand for training. In the last 15 years they have given forty short basic courses to well-attended classes and also more than 100 short refresher courses. Hundreds of so-trained men have had this success and report that it has changed their lives. They are now ablr to achieve more stable results, and both the patients and their parents are happier and more pleased. Appointments are usually scheduled at 6- to 8-week intervals. This enables the operator to successfully treat more patients and/or have much more leisure time for himself and his family. This treatment has been devised so that capable orthodontists can render bct-
Differential
Fig. 4A. Before-and illustrated in Fig. the upper anterior
after-treatment photographs of the patient 4, B to I. Note improved facial contour and teeth, which permits normal upper lip contour.
force method
whose treatment casts desirable repositioning
7
are of
ter treatment for all types of malocclusions, mild or severe (Figs. 44 to 41). However, this is possible only if those who use it have seriously studied its basic biologic foundations. This technique is not intended as a panacea for those who fail to realize the potentials of other techniques. Numerous articles properly describing this technique are in print.l-” Five journals on this technique have been published6 and contain many valuable articles written by various orthodontists. Two editions of a textbook7-s devoted exclusively to the theory and technique of this method have been published in English, French, Spanish, and Italian. There have been many other articles published. Some are excellent, but others purporting to describe it are misleading because, as mentioned before, they introduce retrogressive variations. Some of the best articles describing treatment have been published by orthodontists practicing in .Japan.“, lo However, in order to employ this method successfully, reading alone is not sufficient-practical training is also required. In addition to the short courses
Fig,
4, B and
the
labial
upper that
right the
terior so
C. B, Views
surfaces central
original
teeth
of
of the incisor anterior
force
in
overbite in
technique,
malocclusion
has
a
to
model
necessary
especially
differential
original canines
is
is absolutely
important,
the
upper
to
only). been
patients’
Tissue
banding.
C,
at
anteroposterior
of
this are
on
the
eliminated.
the teeth
has
(Chip
Occlusion
completely
permit
malocclusion
all
cast.
facilitate
type.
At
similar,
been
removed
distal
line
of
Stage
end
from angle 1.
of Note
This
relationship
of
interarch
changes
that
are
Stage
1 in
the
the
end
regardless
of of
their
an-
original
malocclusion.
Fig.
4, D and
tooth remaining
appear
E, Casts
made
tooth
a total positioner
occlusion
achieved
buccal
incisors with
E. D, The
relationships
spaces.
Note
foreshortened at the of
four for
at that in
arch
(two
finishing
the
the of
wires
completion
Stage
completion final
the
during
of have
clinical
anterior
treatment.
and
1
maxillary retention.
Stage been
crowns view This and
of
because patient’s two
2.
The
maintained the
upper
of
their
treatment mandibular).
posterior while central lingual required The
and
anterior
closing and
any lateral
inclinations. 26 patient
months, wore
a
Ihfferential
Fig.
4,
four
first
4
F and
weeks
anchor
G.
F, Occlusal
premolars before
molar
and the
control
views
the
appliances and
of
upper partial
the
upper
second were
placed.
closing
and
deciduous of
G,
lower molars
Cast
extraction
taken
force
arches were at
prior
to
extracted the
end
method
treatment.
9
The
approximately of
Stage
1.
Note
spaces.
mentioned previously, orthodontic students are presently being taught the technique in more than twenty university graduate programs in the United Slates. Also, universities in Australia, Europe, and *Japan teach the method. X few of these universities also teach students about attritional occlusion. As far as we are aware, few, if any, undergraduate dental students are being exposed to the lessons to be learned from studying the development of the normal occlusion of man. ,4ttempting to teach bthc ~~tlgcnise ilIlt the diffcrcl~tial force: methods simutaneously to university graduate orthodontic students is contradictory and, thercfore, can be confusing to both teachers and students. Those who teach the diffcrential force method have no choice other than to contradict what is taught by the edgewise teachers. Attempts to compromise by crolving “midway” treatment methods produce treatment failures. Many recent biologic and mechanical findings have been incorporated into the differential force method. Edgewise-trained operators find it necessary to with t,his relatively new discard previously held concepts in order to succeed method. IXttempting to use the edgewise method on some patients and the differential force method on ot,hers results in poorer treatment results with both techniques. Advantages
of
the
differential
force
treatment
method
1111956 many claims were made in favor of this treatment method. Since then orthodontists using the technique have substantiated these claims. Therefore, it now takes less courage to repeat and elaborate on these claims than was required originally.
Fig.
4, H and
molars righting I, Arch positioner
are
I. H,
in good
auxiliaries form after
at
Occlusal position during
the the
completion teeth
had
views
of
to
withstand
Stage
3. of
been
cast
Stage
treatment. brought
made any 3
at
the
adverse was
of
9
Detailed to their
beginning
pressures
proper
months’ finishing axial
of from duration was
Stage the
3.
torquing in
this
accomplished
inclinations
during
Maxillary or
up-
patient. with
a
Stage
3.
This differential force mcthotl permits early repositioning ot’ the mandible and maintains it throughout treatment. It is therefore not surprising that there is, relatively speaking, minimal Ix&treatment relapse with this method. Universal tooth movements are possible ; sclc~tccl teeth can be held relatively stationary while others move. The separation of tooth-moving forces from thcl arch wire, as is the wsc tluring Stages 2 and 3, permits exact control 01’cr the duration, direction, ant1 magnitude of the forc*c applictl to cnch tooth (Fig. 5). (This is impossible with any technique that relics on the fit bctncen the arch wire and the bracket to create a11tl A-liver forcxx) This ability to tlifferentiate the forces applictl to teeth (even those atljacent to one another) makes this a most precise orthodontic tccahnique. The tlesign of the appliance (inc~luiling auxiliaries) also permits all tooth mo~enicnts to be carried out rapidly a~lcl over great tlistanccs without reac+ivation, Tooth roots can be efficiently torquccl labiolinguall~- and uprighted mesiotlistally without discomfort to the pa.tients or frequent rcaetivation of the appliances. This has put a new complexion OH the diagnosis ant1 treatment of Class II, Division 2 malocclusions. There is greater ~OI~Irol of tooth movement with this method than with others. Some critics mistakenly regard the rigidity of heavy arch wires iis being syiony mous with control, nhe~l act~ually such inflexible rigidity limits and restricts tooth movements. Because the initial rountl ;Irc:h wires nsetl in the differential force hoaT!and light method arc so thin, flexible. tough, ilIlt resilient, :IJ~CI lwnnsc forces can be applied simultaneously, there is greatci* control in all phases of treatment with this method. This makes possible the maximum movement of the dental arches posteriorly or antcriorl;v in the jaws, both in patients requiring and in those not requiring pretreatment reduction of tooth snbstal~(*(~.
Volume
Number
71
1
Diferentinl
force method
11
Fig. 5. A, Combination uprighting spring and lock pin (spring-pin), which securely holds the arch wire in the bracket while uprighting the tooth mesiodistally. Tail of spring is bent to lock assembly into bracket. B, Spring-pin designed for use in plastic bracket. C, Upper and lower 0.020 inch (0.508 mm.) preformed arch wires for use during Stage 3. Prewound 0.012 inch (0.305 mm.) Australian wire torquing auxiliary is in place on the upper arch wire. The use of these relatively heavy arch wires during Stage 3 provides precise control over the application of forces from the auxiliary to the individual teeth.
Fig. 6. Treatment of a Class II, Division 1 malocclusion which did not require pretreatment reduction of tooth substance. The teeth were spaced and the jaws were large enough to hold all teeth on basal bone. Therefore, it was obvious that the hereditary process of continual mesial migration would not cause the teeth to become crowded after treatment, even without prior reduction of tooth substance.
Am. J. Orthod. Janunru 19 7 7
Fig. G portrays treatment of a Class II, IIivision 1 malocclusion which did not require pretreatment reduction of toot.h substance. This patient’s upper and lower anterior teeth have been moved back bodily on basal bone. Treatment of malocclusions which do not require pretreatment tooth extractions or the reduction of mesiodistal tooth widths is easier, simpler, and much more rapid than when such reductions of tooth mass arc required. This patient’s treatment is portrayed to refute the opinions of some writers that it is necessary to extract, mhcn this treatment m&hod is ust~l, in ord~ to control anchorage. Morement of this patient’s anterior teeth back on basal bone is evidence that tooth extractions are not required for anchorage purposes. Far fewer appointnicnt,s are requirrd for treatin, bccomr denuded of tooth-sul)l)ortilig tissues. Failure to reduce t,hcxappropriate amount of tooth substance in both dental arches lcads to posttrcatmcnt relapse. Nonextrac*tion treatment as taught by Angle resulted in a far higher incidcncc of relapse and impaction of third permanent molars t,han occurs in paticxnts totlay \vho ha\r pretreatment removal of a sufficient amount of tooth substance. The avoiclancc, tlven today, of prctreatmcnt tooth reduction by sonic orthodontists because a full-mouthed appearance is consideretl to be attractivr is the cause of many relapses. Ideal and
sequence
of force
values
delivered
by fully
activated
light
arch
wires
auxiliaries
It is imperative Arthur .J. Wilcock.
to use the best quality of arch wire material produced by This light arch wire, being very resilient, moves tee01 over
Differenfial
Fig.
26.
and clusion this in two
Treatment
marked because patient
Treatment used
contact first time
during
completion
the
a Class of
active
17
1 malocclusion
substance
relative
and
left
treatment. the
permanent was
II, Division
right for
with
treatment. of
tooth
upper
presented
proximal upper
of
excess
upper molars
first
months.
Only upper
appliance
jaw
that
the
the five third
arch
upper lower
wires molars
This
had
been first
Just
two
severe
size.
premolars
premolars.
and
The
two
second Note
with
to
prior first
method
force
bimaxillary is
a
protrusion
mutilation
extracted
molars
appliance
premolars
(three
upper
and
erupted
into
normal
maloc-
years
permanent to
33
before were
therapy were
two
the
extracted. lower)
occlusion
were after
therapy.
long distances without having to be frequently reshaped for continued activation. If Mr. Wilcock had not persevered until he produced arch wire with the necessary properties, this treatment method could not have been evolved. When first applied, arch wires and auxiliaries deliver their maximal forces and, as the teeth move, these forces gradually decrease. Fortunately, this sequence of force value application is ideal for maximum rates of tooth movement. Frequent reshaping of arch wires is detrimental because it causes minute changes in the directions of force, which reduce the rate at which the teeth more. Rectangular arch wires must, because of their rigidity, be frequently reactivated during treatment. Therefore, when first changing to the differential force method, operators must discard their habits of seeing the patients every 3 or 4 weeks for adjustments. Not being familiar with the appearance of teeth as they respond to the initial arch wires, they may be tempted to reactivate them. Of
Am.
J. Ovthod.
Jan.uary1977
Fig. 27.
Treatment of a patient with Class II, Division 1 malocclusion. The four first premolars were extracted. The same upper and lower arch wires of 0.016 inch (0.406 mm.) diameter were used throughout treatment without once being removed from the mouth. Active treatment time was just under 10 months. For further explanation, see text.
course, if an arch wire becomes distorted, it is imperative to correct it as soon as possible because tooth movements are so ra.pid that such distortions could rapidly move teeth far from their correct paths, Normally, appointments with this method are at intervals of 6 weeks. Fig. 27 portrays treatment of a patient with a Class II, Division 1 malocclusion. The four first premolars were extracted 3 weeks before the start of appliance therapy. The same upper and lower arch wires of 0.016 inch (0.406 mm.) diameter were used throughout treatment without once being removed from the to place the arch mouth. Two adjustments vvcre made durin, 0‘ treatment-first, wires in the slots of the brackets of the four second premolars after the extraction spaces were closed and, second, to place uprighting springs and torquing auxiliaries at the beginning of the final stage of treatment. The distal free ends of the arch wires were kept cinched tightly against the molar tubes to prevent rcopening of extraction spaces during the final stage. Treatment time was under 10 months. When the most powerful canine root-tipping springs made from 0.018 inch (0.457 mm.) Australian wire are used, canine roots can be tipped back even farther and more rapidly than was done for this patient. The benefits of placing fully activated arch wires and auxiliaries are manifold :
Differential
Fig. 28. Drawings begin treatment
of fully activated 0.016 inch (0.406 mm.) arch of the Class II, Division 1 extraction case (A) and
nonextraction case (8) shown. The amount wires can be appreciated by noting where the models at the left. Casts in the center brackets. Casts at the right show the results
force method
35
wires actually used the Class II, Division
to 2
of bite opening or anchor bends in the arch the anterior portions of the arch wires rest on show the arch wires engaged in the anterior of treatment for each case.
1. The rates of tooth movement are increased. 2. Reciprocal forces are caused to become more efficient. 3. Variations in both the values and directions of tooth-moving forces (changes which retard tooth movement and are inevitable whenever appliances are reactivated) are eliminated. 4. Chairside time is reduced. 5. The number of appointments required throughout treatment is reduced. 6. The over-all treatment time is greatly reduced. The initial arch wires made from Wilcock stainless steel wire for two malocclusions are portrayed in Fig. 28. They are so resilient that, when properly activated, they can deliver the proper tooth-moving forces for up to 3 months without being reactivated.
36
Am. J. Orthod. JamuarU 19 7 7
Begg cmd Keslillg
The forces exerted by these arch wires are proportionate to the requirements of each individual tooth. They cause far less discomfort to patients than the forces from rigid rectangular arch wires which have to be frequently reactivated throughout treatment. Also, the fact that these highly resilient wires can deliver the desired forces over a great range of tooth movement eliminates the need for frequent adjustments. This also adds greatly to the patient’s comfort. In this method, arch wires and tooth-moving auxiliaries still have toothmoving forces in them at the completion of treatment. Therefore, the appliances must be removed before too much ovcrmovement occurs. Attritional
occlusion-The
key
to future
advances
in dentistry
Textbook normal occlusion is erroneously accepted as the foundation, the starting point, the basis, the one grand object of dentistry as a whole. Because of this, advances in many branches of dentistry, including orthodontics, have been retarded or misdirected. The refined soft food of civilized man is accelerating the rate of evolutionary reduction and degeneration of his teeth because the teeth now have a lower survival value than in Stone Age man. It is hard to imagine that the whole method of modern food production will be modified in order to promote dental and periodontal health. Some day, as a partial solution to this problem, orthodontists ma.y augment their mechanotherapy with some form of equilibration and continual reduction of tooth substance. This could be accomplished by mechanical stripping and grinding at regular intervals carefully related to each patient’s rates of eruption and mesial migration. Patients could bc instructed to use chewing gum containing varying amounts of tough roughage and carborundum dust to wear away cusps and proximal surfaces. If civilized man’s teeth were subject to such controlled attrition, orthodontists would not have the problem of orthodontic extraction spaces sometimes remaining slightly open after treatment. There would be no intcrdigitating tooth CUSPS to interfere with closure of these sma.11spaces by the hereditary process of mrsial migration. Tears ago a dentist reported that he gave a patient chewing gum with a gritty substance incorporated into it in order to equilibrate his teeth. The patient’s occlusion began to improve, but this treatment was quickly discontinued as soon as interproximal attrition was observed. The dentist feared that loss of oncpoint proximal contacts would, according to G. V. Black’s teaching, be harmful. The roots of civilized man’s teeth cannot migrate closer together because their crowns do not become narrower mesiodistally. This prevents the fibers of the periodontal membranes from becoming shorter with increasing age, as occurs naturally in Stone Age man. Therefore, the transseptal fibers of the periodontal membrane in civilized man are subjected to ever-increasing and presumably destructive stretching forces. Periodontists who complain that artificial reduction of the widths of teeth causes harmful compression of periodontal membranes and their fibers need to study Stone Age dentitions.
Volunae Nwmber
71
Diflerentinl
1
CIVILIZED
’
A
A n
A~AECC
29.
gingiva from too
Diagrammatic of
shallow
attrition. space.
to The
harbor gingival
October,
A
and
to
A& of
civilized
Friction bacteria.
triangles
papilla. Surg.,
man disease.
A, Free
gingival Oral
comparison*
primitive
periodontal
‘Maturity
n
A
from The the
B, Level of
changes
his
to crude
at
show
relative of gingival
kept
space sizes,
soft-tissue trough.
at
different how
food
interproximal
margin. Height
the man
represent B,
37
MAN
A m:,escel,m
m 4
Fig.
PRIMITIVE
force method
was different
attachment (From
ages
of
primitive the
gingival
kept ages, Begg,
of tooth. P.
teeth
and
remained
free
(A
trough
small to
the
man by
interproximal
the
interproximal
to
B)
C, Interproximal R.:
Am.
J.
Orthod.
1945.)
Civilized man’s dentition is pathogenic. It contracts diseases, dental caries, and periodontitis in the stagnation regions protected by plaque. The sites of these stagnation regions (namely, proximal surfaces and occlusal pits and fissures) were pointed out by G. V. Black. Because of their lack of knowledge of Stone Age attritional occlusion, univer.. sity dental research workers are not aware that plaque formation is caused by the absence of abrasive and cleansing properties in civilized man’s food. When they realize this true cause of plaque, it should be useful to them in discovering means to prevent both dental caries and periodontal disease. In Stone Age man proximal attrition wore away the contact points of his teeth and turned them into flat, continually enlarging contact surfaces. The process of mesial migration kept his teeth in proximal contact as their mesiodistal widths were being continually reduced. Consequently, the interdental space remained small and frequently became smaller as the teeth continually erupted. In civilized man the triangular interproximal space, as portrayed in Fig. 29, becomes gradually larger with age in the absence of tooth attrition. The apex of this space is the point of contact of the neighboring teeth, and the walls of the neighboring teeth comprise the two sides. The base is defined by the transseptal fibers. This pyramidical interproximal space continually enlarges in civilized man as the teeth erupt and the transseptal fibers move toward the necks of the teeth. The interdental papilla continues to proliferate ; however, the space finally becomes so large that the papilla can no longer fill it. This unnatural interdental space in civilized man, continually increasing in
Am. J. Orthod. January 1977
size, is a stagnation region where plaque forms and is protected from dislodgmcnt by sheltering of the walls of the teeth and the papilla. Reduction of the mesiodistal widths of adults’ teeth can eliminate existing interproximal periodontitis. Simultaneously, small areas of recurrent dental caries at the gingival margins of proximal fillings are eliminated. Mention of this ability to prevent caries and periodontal disease by simulating tooth attrition has been made here to draw to the attention of the dental profession as a whole the fact that advances can and must be made in other branches of dentistry through the application of knowledge gained from studying Stone Age attrition. For instance, proximal fillings should have flat contact surfaces. Original tooth widths should not be increased by restorations, as this may cause periodontitis, interproximal caries, and increased tooth crowding. Fixed bridgework is limited in the number of years of service because its mesiodistal length is not continually reduced and the abutment teeth cannot migrate mesially at different rates. Normally the posterior teeth must migrate farther and, therefore, travel at a greater rate than the anterior teeth. Also, because of continual tooth eruption, the entire bridge moves occlusally and the abutment teeth develop unfavorable clinical crown/root ratios. This results in reduced alveolar support and the teeth become more susceptible to occlusal and lateral stresses. Therefore, the abutment, teet,h become mobile and the bridge, as well as the supporting teeth, must be removed to avoid accelerated alveolar loss from periodontal disease and ultimate exfoliation. Simulation of attritional occlusion’s relatively flat occlusal plant and cdge-toedge anterior tooth relationships would add greatly to complete denture stability. Flat occlusal surfaces with relatively sharp edges have long ago proved to be the most efficient masticatory apparatus. Unworn cusps and fossae have no more place in artificial dentures than they do in the natural adult dentition. The lateral forces created by cusps are unnecessary and may actually bc a contributing cause of denture instability. A recent article’” indicates that progressive minds in other branches of dentistry are beginning to examine attrit,ional occlusion as a guide to both diagnosis and treatment planning. Drs. H. 3. Cooperman and 8. B. Willard studied the attritional planes of occlusion of Eskimos, Australian aborigines, Mexican Indians, Zulus, and Europeans. They noted the reduction in the curve of Spee, the absence of cusps, the loss of incisal edges and anterior overbite, and the forward position of the mandible. On the basis of this study, they have outlined a method to determine the correct (attritional) occlusal plane for each patient from landmarks on an upper model. They believe that the use of this plane can aid in diagnosis, increase stability, and simplify denture construction and oral reconstruction. Summary
Knowing how to execute differential force treatment with the proper appliances gives the orthodontist a great advantage, and treatment of any type of malocclusion, including mutilated cases and those not requiring reduction of tooth substance, becomes simple. In order to derive such benefits from the differential force technique, one
Volume Number
71
Differentin
1
force method
39
must use it exclusively and not attempt the simultaneous use of other methods, which leads to confusion in both diagnosis and appliance design. It is absolutely necessary to use the cold-drawn, heat-treated, highly resilient wire as produced especially for this method by A. J. Wilcock of Australia. Failures are caused by the use of other wire. The knowledge gained from the study of Stone Age attritional occlusion must be applied as much as is possible during orthodontic treatment. It will affect the diagnosis, amount and method of tooth mass reduction (if indicated), and final positions of teeth for maximum stability and esthetics. To date the differential force method is the only orthodontic technique that was developed to fit the true biologic requirements of man. The practice of the other branches of dentistry must also be related as nearly as possible to the principles found in the natural evolutionary development of man’s dentition, as found in his Stone Age attritional occlusion. To date we have, in orthodontics, the light wire differential force treat,ment method which is in accordance with this principle. The future must bring similar changes in many other branches of dentistry and, it is hoped, even more in orthodontics. REFERENCES
1. Begg,
P. R.: Progress report of observations on attrition of the teeth in its relation to and tooth decay, Aust. 5. Dent. 42: 3X-320, 1938. Begg, P. R.: Stone Age man’s dentition, AM. J. ORTHOD. 40: 298-312, 373-383, 462-475, 517-531, 1954. Begg, P. R.: Differential force in orthodontic treatment, AM. J. ORTHOD. 42: 481-510, 1956. Kesling, H. D.: Have recent technical advances in orthodontics made possible successful treatment for more people8 Dent. Clin. North Am., pp. 821-829, November, 1960. W. B. Saunders Company, Philadelphia. Begg, P. R.: Light arch wire technique, AM. J. ORTHOD. 47: 30-48, 1961. Kesling, P. C. (editor) : Begg J. Orthod. Theory and Treatment, July, 1962; April, 1963; September, 1964; January, 1968; June, 1969. Begg, P. R., and Kesling, P. C.: Begg Orthodontic Theory and Technique, ed. 1, Philadelphia, 1965, W. B. Saunders Company, pp. 5-51. Begg, P. R., and Kesling, P. C.: Begg Orthodontic Theory and Technique, ed. 2, Philadelphia, 1971, W. B. Saunders Company, pp. l-57. Enoki, K.: Begg light wire technique, Jap. Dent. Rev., pp. l-27, January, 1964. Motohashi, K., Ohno, T., Shimizu, K., Shimoyama, K., Yamamoto, Y., and Ohtsuka, E.: Eight teeth extraction cases treated wit,h the Begg technique, .J. Jap. Orthod. Sot. 32: 321-343, 1973. Begg, P. R.: Some aspects of the etiology of malocclusion of the teeth, unpublished thesis presented by P. R. Begg to University of Adelaide, 1935. Payne, G. S.: The effect of intermaxillary elastic force on the temporomandibular articulation in the growing macaque monkey, Am J. ORTHOD. 60: 491-504, 1971. Cooperman, H. N.: HIP plane of occlusion in oral diagnosis, Dent. Survey 51: 60, 62, 1975.
pyorrhea 2. 3. 4.
5. 6. 7. 8. 9. 10.
11. 12. 13. Dr. Dr.
Begg: Kesling:
North Terrace Orthodontic
(5000) Center
(46391)
71, Number
1, January,
ORIGINAL
1977
ARTICLES
The differential force method of orthodontic treatment P. R. Begg,
D.D.Sc., L.D.S., B.D.Sc., and Peter C. Kesling,
Adelaide, South Australia,
Many
D.D.S.
and Westville, Ind.
wish to learn but few the price will pay. 3uveua1, first century A.D.
T
his essay is being written to explain the light wire differential force technique free of unnecessary and incorrect variations. It is hoped that this will help eliminate the confusion that has been caused by several published accounts which, while purporting to describe this treatment, actually are misleading because they contain retrogressive alterations. Some orthodontists now employing this technique have received only practical training in the manipulation of the appliances and very little teaching on its theoretic basis. Therefore, a brief description of Stone Age man’s attritional occlusion, the basis upon which this method was developed, is also included. Unless this section is carefully studied, the part describing appliance therapy will be of little value to those using this method to treat patients. This essay is an abridged and revised version of two lectures delivered at the fortyfifth annual meeting of the Great Lakes Society of Orthodontists, Oct. 5 to 9, 1974. We wish to thank all members of the Kesling and Rocke Group of Westville, Ind. Without their illustrations and records of appliance therapy throughout treatment, this essay would not achieve its purpose.
Also, to dissuade orthodontists from attempting to employ edgewise brackets in conjunction with this technique, a brief analysis of root-moving forces delivered by the edgewise appliance is included. In the hope of holding the attention of the more clinically oriented orthodontists and of making this article less dreary, the records of treated cases and recent improvements in this method will be interspersed throughout its entirety. 1
Am. J. Orthod. January 1977
Fig.
1. Tree gtment
the
extent
to (the
t he
size
of of
with the
and lower upper left fir st permanent
havi e previc susiy
the
protrusion
been
Begg of
jaws,
the
the right
severest and
molars) published
differential anterior left were in the
force teeth
condition first
1961,
of
I (P.
premolars
extracted July,
method.
and
prior issue
This
excess R.
Begg) also
to
appliance this
the
tooth have
and of
is, from of the
Sitandpc
subsi &a rice treatec
Eight
upper
anI d lower
therapy.
( TI7ese
JOURNAL.)
hint of re lative teeth right rc tcords
Differential
force method
3
Fig. 2. A, Molar band with buccal tube (0.036 inch inner diameter and 0.250 inch long, 0.914 mm. I.D. and 0.635 mm. long) and intermaxillary hook attached to buccal surface. Note that tube is positioned near the gingival band margin, to help prevent the arch wire from being distorted from occlusal forces. A ball-ended hook is also attached to the lingual surface of each molar band to accept elastics or ligature ties, if necessary. 6, Modified ribbon arch bracket (TP 256-500) especially designed for light wire technique, prewelded to a preformed band. Will accept 0.016 inch (0.406 mm.) arch wires in Stage 1, and 0.018 or 0.020 inch (0.457 or 0.508 mm.) wires in Stages 2 and 3. Permits free crown tipping or controlled root torque when required.
The treatment of a severe malocclusion is shown in Fig. 1. This patient’s teeth were so large, compared with the space available in her jaws, that eight teeth (the four first premolars and the four first permanent molars) had to be extracted prior to appliance therapy. Very few patients (2 to 3 per cent) have such severe malocclusions as to require the pretreatment ext,raction of these eight teeth. Development
of the
light
wire
differential
force
technique
Early variations of the edgewise technique. This method would not have been developed if one of us (P. R. Begg) had not been taught by Dr. Edward H. Angle in 1924-25 to use the edgewise appliance. We owe him a debt beyond repayment. However, in contrast to the original nonextraction method of using the edgewise mechanism as taught by Dr. Angle, I (P. R. Begg) began to extract teeth prior to treatment, when necessary. This decision was made as a result of studying Stone Age Australian aboriginal and other dentitions in relation to the etiology of malocclusion. In 1928 Australian orthodontists were shown the results of treatment with the edgewise mechanism after extraction of the four first premolars in those patients who inherited teeth too large for their jaws. The only change made at that time in Dr. Angle’s edgewise mechanism was the use of large round buccal molar tubes instead of rectangular tubes. These round tubes have evolved into the smaller buccal tubes that we now employ in conjunction with the modified ribbon arch brackets (Fig. 2). This change was made so that frictional binding of arch wires would not prevent horizontal elastics from closing extraction spaces. Also, many of these patients had to wear headgear. These orthodontists were, with the exception of Dr. Stanley Wilkinson, noncommittal concerning these treatment results. They were surprised by the unorthodoxy of pretreatment tooth extractions. From 1928 until the present day tooth extraction has continued to be used as an adjunct to orthodontic treatment whenever this appears to be necessary. It was recognition of the fact that the lifelong hereditary forces of mesial migration and continual eruption are very light that led to the discarding of the
Am. J. Orthod. Januarf~ 1977
Fig. 3A.
Facial
photographs
years
at the
beginning
old
before of nonextraction
(top)
and
after
treatment,
treatment which
(bottom]. lasted
Patient
was
12
13 months.
edgewise treatment method. This change was made in order to simulate Nature by employing light continuous orthodontic force values instead of the heavy intermittent forces used in the edgewise technique. A metallurgist, Arthur .J. Wilcock of Victoria, Australia, was able, after years of experimentation, to produce arch wire material suitable for the technique. The fact that the lighter force values employed cause less loosening of teeth, less discomfort, and less damage to roots and tooth-invcst,ing tissues is evidence that these forces arc optimal for tissue tolerance. The records of a patient treated with this technique, using these light force values and directly bonded brackets, are shown in Fig. 3. Those orthodontists who use this method properly, and who formerly used the edgewise technique, report that their average treatment time is much less than that previously required. Furthermore, it now takes only one third to one fourth the chair time for each patient. This technique and orthodontic ccphalomrtrics were developed concurrently, but independently of one another. Most anthropologists and biomctricians con sider that it is impossible to locate landmarks accurately on lateral cephalometric head films. For this and other reasons, we hare never felt secure in following any of these concepts in the planning of our patients’ treatment.
Fig.
3, B to
that
this
the
end
of
anterior ments
are seen
a tooth
3,
edge
to
to
on help
views plus
profile,
on worn
the
six
molar upper
of upper
a tooth
of the
dental
teeth
the
positioner
of
for
indicated
C, Occlusion
nonextraction
at
cases).
I. Direct
D, Final
bonded
occlusion.
in nonextraction
before dental
decision end
teeth.
of teeth.
5
Note attach-
Stage
cases.
The
3 was patient
results.
arches
at the
anterior
Diagnosis
treatment.
is Class teeth.
situation
treatment
to
extraction
relationship the
force method
in most
anterior
location to
the
simultaneously
six retain
prior
without
and the
led
F, Alignment
mass. had
arch
soft-tissue
occur
as is normally
positioner
upper
treated
edge,
in place
(5 months),
the
2 malocclusion
2 (which
in
attachments patient
Division
E to G. E, Occlusal
as the
of tooth
II,
be successfully
1 and
be short
spaces well
could
teeth
relatively
Fig.
B, Class
Stages
can
wore
D.
patient
Diferentinl
to of
G,
3 months.
treatment. arches
treat
Stages Arch
form
this 1 and and
The
presence
relative
to
patient
without
2.
Note
tooth
the
of
basal
slight
bone,
as
a reduction direct
alignment
bonded after
the
Am. J. O?%hod. January 1977
:‘li
b
Fig. 3H. a and b, Molded polycarbonate bracket and special lock pin of the type used in the treatment of this patient. c, Small stainless steel mesh pad which, when spot-welded to the base of the metal bracket permits it to be bonded directly to the tooth surface.
Treatment procedures must be based on knowledge gained from studying the occlusion of Stone Age man. Of primary concern is the difference between unworn and attritional tooth mass, together with the realization that everyone has his own hereditary rate of continual mesial migration and vertical eruption of the teeth. Treatment planning is made with these concepts in mind. This propdure is more accurate than depending upon static, two-dimensional cephalometrics. The lack of attrition in the presence of mesial migration and continual eruption indicates the need for reduction of tooth mass in most patients. Recognition,
use,
and
teaching
of the
technique
It is fortunate that, 18 years ago, I)r. H. I). Kesling and I)r. (George Dinham visited my (I’. R. Begg’s) office in Adelaide, observed differential force treatment, and were impressed with it. They also seemed, in this short time, to get the message about attritional occlusion, mesial migration, and the continual eruption of teeth. It was also fortunate that they had the foresight and determination to go back to their homes in the United States and, in spite of many disappointments, to persevere with the differential force trcat,ment, using the proper appliances. They not only used the differential forcr light wire treatment method themselves, but Dr. H. I). Kesling instilled into his partners in the Orthodontic Group at Westville, Indiana, the urge and determination to use this method from that time on. By the time they had completed their first 100 cases with this technique, the Orthodontic Center at Westville was completed. Two hundred fifty men were invited and attended t,hree different showings of this work. From these showings, there developed a demand for training. In the last 15 years they have given forty short basic courses to well-attended classes and also more than 100 short refresher courses. Hundreds of so-trained men have had this success and report that it has changed their lives. They are now ablr to achieve more stable results, and both the patients and their parents are happier and more pleased. Appointments are usually scheduled at 6- to 8-week intervals. This enables the operator to successfully treat more patients and/or have much more leisure time for himself and his family. This treatment has been devised so that capable orthodontists can render bct-
Differential
Fig. 4A. Before-and illustrated in Fig. the upper anterior
after-treatment photographs of the patient 4, B to I. Note improved facial contour and teeth, which permits normal upper lip contour.
force method
whose treatment casts desirable repositioning
7
are of
ter treatment for all types of malocclusions, mild or severe (Figs. 44 to 41). However, this is possible only if those who use it have seriously studied its basic biologic foundations. This technique is not intended as a panacea for those who fail to realize the potentials of other techniques. Numerous articles properly describing this technique are in print.l-” Five journals on this technique have been published6 and contain many valuable articles written by various orthodontists. Two editions of a textbook7-s devoted exclusively to the theory and technique of this method have been published in English, French, Spanish, and Italian. There have been many other articles published. Some are excellent, but others purporting to describe it are misleading because, as mentioned before, they introduce retrogressive variations. Some of the best articles describing treatment have been published by orthodontists practicing in .Japan.“, lo However, in order to employ this method successfully, reading alone is not sufficient-practical training is also required. In addition to the short courses
Fig,
4, B and
the
labial
upper that
right the
terior so
C. B, Views
surfaces central
original
teeth
of
of the incisor anterior
force
in
overbite in
technique,
malocclusion
has
a
to
model
necessary
especially
differential
original canines
is
is absolutely
important,
the
upper
to
only). been
patients’
Tissue
banding.
C,
at
anteroposterior
of
this are
on
the
eliminated.
the teeth
has
(Chip
Occlusion
completely
permit
malocclusion
all
cast.
facilitate
type.
At
similar,
been
removed
distal
line
of
Stage
end
from angle 1.
of Note
This
relationship
of
interarch
changes
that
are
Stage
1 in
the
the
end
regardless
of of
their
an-
original
malocclusion.
Fig.
4, D and
tooth remaining
appear
E, Casts
made
tooth
a total positioner
occlusion
achieved
buccal
incisors with
E. D, The
relationships
spaces.
Note
foreshortened at the of
four for
at that in
arch
(two
finishing
the
the of
wires
completion
Stage
completion final
the
during
of have
clinical
anterior
treatment.
and
1
maxillary retention.
Stage been
crowns view This and
of
because patient’s two
2.
The
maintained the
upper
of
their
treatment mandibular).
posterior while central lingual required The
and
anterior
closing and
any lateral
inclinations. 26 patient
months, wore
a
Ihfferential
Fig.
4,
four
first
4
F and
weeks
anchor
G.
F, Occlusal
premolars before
molar
and the
control
views
the
appliances and
of
upper partial
the
upper
second were
placed.
closing
and
deciduous of
G,
lower molars
Cast
extraction
taken
force
arches were at
prior
to
extracted the
end
method
treatment.
9
The
approximately of
Stage
1.
Note
spaces.
mentioned previously, orthodontic students are presently being taught the technique in more than twenty university graduate programs in the United Slates. Also, universities in Australia, Europe, and *Japan teach the method. X few of these universities also teach students about attritional occlusion. As far as we are aware, few, if any, undergraduate dental students are being exposed to the lessons to be learned from studying the development of the normal occlusion of man. ,4ttempting to teach bthc ~~tlgcnise ilIlt the diffcrcl~tial force: methods simutaneously to university graduate orthodontic students is contradictory and, thercfore, can be confusing to both teachers and students. Those who teach the diffcrential force method have no choice other than to contradict what is taught by the edgewise teachers. Attempts to compromise by crolving “midway” treatment methods produce treatment failures. Many recent biologic and mechanical findings have been incorporated into the differential force method. Edgewise-trained operators find it necessary to with t,his relatively new discard previously held concepts in order to succeed method. IXttempting to use the edgewise method on some patients and the differential force method on ot,hers results in poorer treatment results with both techniques. Advantages
of
the
differential
force
treatment
method
1111956 many claims were made in favor of this treatment method. Since then orthodontists using the technique have substantiated these claims. Therefore, it now takes less courage to repeat and elaborate on these claims than was required originally.
Fig.
4, H and
molars righting I, Arch positioner
are
I. H,
in good
auxiliaries form after
at
Occlusal position during
the the
completion teeth
had
views
of
to
withstand
Stage
3. of
been
cast
Stage
treatment. brought
made any 3
at
the
adverse was
of
9
Detailed to their
beginning
pressures
proper
months’ finishing axial
of from duration was
Stage the
3.
torquing in
this
accomplished
inclinations
during
Maxillary or
up-
patient. with
a
Stage
3.
This differential force mcthotl permits early repositioning ot’ the mandible and maintains it throughout treatment. It is therefore not surprising that there is, relatively speaking, minimal Ix&treatment relapse with this method. Universal tooth movements are possible ; sclc~tccl teeth can be held relatively stationary while others move. The separation of tooth-moving forces from thcl arch wire, as is the wsc tluring Stages 2 and 3, permits exact control 01’cr the duration, direction, ant1 magnitude of the forc*c applictl to cnch tooth (Fig. 5). (This is impossible with any technique that relics on the fit bctncen the arch wire and the bracket to create a11tl A-liver forcxx) This ability to tlifferentiate the forces applictl to teeth (even those atljacent to one another) makes this a most precise orthodontic tccahnique. The tlesign of the appliance (inc~luiling auxiliaries) also permits all tooth mo~enicnts to be carried out rapidly a~lcl over great tlistanccs without reac+ivation, Tooth roots can be efficiently torquccl labiolinguall~- and uprighted mesiotlistally without discomfort to the pa.tients or frequent rcaetivation of the appliances. This has put a new complexion OH the diagnosis ant1 treatment of Class II, Division 2 malocclusions. There is greater ~OI~Irol of tooth movement with this method than with others. Some critics mistakenly regard the rigidity of heavy arch wires iis being syiony mous with control, nhe~l act~ually such inflexible rigidity limits and restricts tooth movements. Because the initial rountl ;Irc:h wires nsetl in the differential force hoaT!and light method arc so thin, flexible. tough, ilIlt resilient, :IJ~CI lwnnsc forces can be applied simultaneously, there is greatci* control in all phases of treatment with this method. This makes possible the maximum movement of the dental arches posteriorly or antcriorl;v in the jaws, both in patients requiring and in those not requiring pretreatment reduction of tooth snbstal~(*(~.
Volume
Number
71
1
Diferentinl
force method
11
Fig. 5. A, Combination uprighting spring and lock pin (spring-pin), which securely holds the arch wire in the bracket while uprighting the tooth mesiodistally. Tail of spring is bent to lock assembly into bracket. B, Spring-pin designed for use in plastic bracket. C, Upper and lower 0.020 inch (0.508 mm.) preformed arch wires for use during Stage 3. Prewound 0.012 inch (0.305 mm.) Australian wire torquing auxiliary is in place on the upper arch wire. The use of these relatively heavy arch wires during Stage 3 provides precise control over the application of forces from the auxiliary to the individual teeth.
Fig. 6. Treatment of a Class II, Division 1 malocclusion which did not require pretreatment reduction of tooth substance. The teeth were spaced and the jaws were large enough to hold all teeth on basal bone. Therefore, it was obvious that the hereditary process of continual mesial migration would not cause the teeth to become crowded after treatment, even without prior reduction of tooth substance.
Am. J. Orthod. Janunru 19 7 7
Fig. G portrays treatment of a Class II, IIivision 1 malocclusion which did not require pretreatment reduction of toot.h substance. This patient’s upper and lower anterior teeth have been moved back bodily on basal bone. Treatment of malocclusions which do not require pretreatment tooth extractions or the reduction of mesiodistal tooth widths is easier, simpler, and much more rapid than when such reductions of tooth mass arc required. This patient’s treatment is portrayed to refute the opinions of some writers that it is necessary to extract, mhcn this treatment m&hod is ust~l, in ord~ to control anchorage. Morement of this patient’s anterior teeth back on basal bone is evidence that tooth extractions are not required for anchorage purposes. Far fewer appointnicnt,s are requirrd for treatin, bccomr denuded of tooth-sul)l)ortilig tissues. Failure to reduce t,hcxappropriate amount of tooth substance in both dental arches lcads to posttrcatmcnt relapse. Nonextrac*tion treatment as taught by Angle resulted in a far higher incidcncc of relapse and impaction of third permanent molars t,han occurs in paticxnts totlay \vho ha\r pretreatment removal of a sufficient amount of tooth substance. The avoiclancc, tlven today, of prctreatmcnt tooth reduction by sonic orthodontists because a full-mouthed appearance is consideretl to be attractivr is the cause of many relapses. Ideal and
sequence
of force
values
delivered
by fully
activated
light
arch
wires
auxiliaries
It is imperative Arthur .J. Wilcock.
to use the best quality of arch wire material produced by This light arch wire, being very resilient, moves tee01 over
Differenfial
Fig.
26.
and clusion this in two
Treatment
marked because patient
Treatment used
contact first time
during
completion
the
a Class of
active
17
1 malocclusion
substance
relative
and
left
treatment. the
permanent was
II, Division
right for
with
treatment. of
tooth
upper
presented
proximal upper
of
excess
upper molars
first
months.
Only upper
appliance
jaw
that
the
the five third
arch
upper lower
wires molars
This
had
been first
Just
two
severe
size.
premolars
premolars.
and
The
two
second Note
with
to
prior first
method
force
bimaxillary is
a
protrusion
mutilation
extracted
molars
appliance
premolars
(three
upper
and
erupted
into
normal
maloc-
years
permanent to
33
before were
therapy were
two
the
extracted. lower)
occlusion
were after
therapy.
long distances without having to be frequently reshaped for continued activation. If Mr. Wilcock had not persevered until he produced arch wire with the necessary properties, this treatment method could not have been evolved. When first applied, arch wires and auxiliaries deliver their maximal forces and, as the teeth move, these forces gradually decrease. Fortunately, this sequence of force value application is ideal for maximum rates of tooth movement. Frequent reshaping of arch wires is detrimental because it causes minute changes in the directions of force, which reduce the rate at which the teeth more. Rectangular arch wires must, because of their rigidity, be frequently reactivated during treatment. Therefore, when first changing to the differential force method, operators must discard their habits of seeing the patients every 3 or 4 weeks for adjustments. Not being familiar with the appearance of teeth as they respond to the initial arch wires, they may be tempted to reactivate them. Of
Am.
J. Ovthod.
Jan.uary1977
Fig. 27.
Treatment of a patient with Class II, Division 1 malocclusion. The four first premolars were extracted. The same upper and lower arch wires of 0.016 inch (0.406 mm.) diameter were used throughout treatment without once being removed from the mouth. Active treatment time was just under 10 months. For further explanation, see text.
course, if an arch wire becomes distorted, it is imperative to correct it as soon as possible because tooth movements are so ra.pid that such distortions could rapidly move teeth far from their correct paths, Normally, appointments with this method are at intervals of 6 weeks. Fig. 27 portrays treatment of a patient with a Class II, Division 1 malocclusion. The four first premolars were extracted 3 weeks before the start of appliance therapy. The same upper and lower arch wires of 0.016 inch (0.406 mm.) diameter were used throughout treatment without once being removed from the to place the arch mouth. Two adjustments vvcre made durin, 0‘ treatment-first, wires in the slots of the brackets of the four second premolars after the extraction spaces were closed and, second, to place uprighting springs and torquing auxiliaries at the beginning of the final stage of treatment. The distal free ends of the arch wires were kept cinched tightly against the molar tubes to prevent rcopening of extraction spaces during the final stage. Treatment time was under 10 months. When the most powerful canine root-tipping springs made from 0.018 inch (0.457 mm.) Australian wire are used, canine roots can be tipped back even farther and more rapidly than was done for this patient. The benefits of placing fully activated arch wires and auxiliaries are manifold :
Differential
Fig. 28. Drawings begin treatment
of fully activated 0.016 inch (0.406 mm.) arch of the Class II, Division 1 extraction case (A) and
nonextraction case (8) shown. The amount wires can be appreciated by noting where the models at the left. Casts in the center brackets. Casts at the right show the results
force method
35
wires actually used the Class II, Division
to 2
of bite opening or anchor bends in the arch the anterior portions of the arch wires rest on show the arch wires engaged in the anterior of treatment for each case.
1. The rates of tooth movement are increased. 2. Reciprocal forces are caused to become more efficient. 3. Variations in both the values and directions of tooth-moving forces (changes which retard tooth movement and are inevitable whenever appliances are reactivated) are eliminated. 4. Chairside time is reduced. 5. The number of appointments required throughout treatment is reduced. 6. The over-all treatment time is greatly reduced. The initial arch wires made from Wilcock stainless steel wire for two malocclusions are portrayed in Fig. 28. They are so resilient that, when properly activated, they can deliver the proper tooth-moving forces for up to 3 months without being reactivated.
36
Am. J. Orthod. JamuarU 19 7 7
Begg cmd Keslillg
The forces exerted by these arch wires are proportionate to the requirements of each individual tooth. They cause far less discomfort to patients than the forces from rigid rectangular arch wires which have to be frequently reactivated throughout treatment. Also, the fact that these highly resilient wires can deliver the desired forces over a great range of tooth movement eliminates the need for frequent adjustments. This also adds greatly to the patient’s comfort. In this method, arch wires and tooth-moving auxiliaries still have toothmoving forces in them at the completion of treatment. Therefore, the appliances must be removed before too much ovcrmovement occurs. Attritional
occlusion-The
key
to future
advances
in dentistry
Textbook normal occlusion is erroneously accepted as the foundation, the starting point, the basis, the one grand object of dentistry as a whole. Because of this, advances in many branches of dentistry, including orthodontics, have been retarded or misdirected. The refined soft food of civilized man is accelerating the rate of evolutionary reduction and degeneration of his teeth because the teeth now have a lower survival value than in Stone Age man. It is hard to imagine that the whole method of modern food production will be modified in order to promote dental and periodontal health. Some day, as a partial solution to this problem, orthodontists ma.y augment their mechanotherapy with some form of equilibration and continual reduction of tooth substance. This could be accomplished by mechanical stripping and grinding at regular intervals carefully related to each patient’s rates of eruption and mesial migration. Patients could bc instructed to use chewing gum containing varying amounts of tough roughage and carborundum dust to wear away cusps and proximal surfaces. If civilized man’s teeth were subject to such controlled attrition, orthodontists would not have the problem of orthodontic extraction spaces sometimes remaining slightly open after treatment. There would be no intcrdigitating tooth CUSPS to interfere with closure of these sma.11spaces by the hereditary process of mrsial migration. Tears ago a dentist reported that he gave a patient chewing gum with a gritty substance incorporated into it in order to equilibrate his teeth. The patient’s occlusion began to improve, but this treatment was quickly discontinued as soon as interproximal attrition was observed. The dentist feared that loss of oncpoint proximal contacts would, according to G. V. Black’s teaching, be harmful. The roots of civilized man’s teeth cannot migrate closer together because their crowns do not become narrower mesiodistally. This prevents the fibers of the periodontal membranes from becoming shorter with increasing age, as occurs naturally in Stone Age man. Therefore, the transseptal fibers of the periodontal membrane in civilized man are subjected to ever-increasing and presumably destructive stretching forces. Periodontists who complain that artificial reduction of the widths of teeth causes harmful compression of periodontal membranes and their fibers need to study Stone Age dentitions.
Volunae Nwmber
71
Diflerentinl
1
CIVILIZED
’
A
A n
A~AECC
29.
gingiva from too
Diagrammatic of
shallow
attrition. space.
to The
harbor gingival
October,
A
and
to
A& of
civilized
Friction bacteria.
triangles
papilla. Surg.,
man disease.
A, Free
gingival Oral
comparison*
primitive
periodontal
‘Maturity
n
A
from The the
B, Level of
changes
his
to crude
at
show
relative of gingival
kept
space sizes,
soft-tissue trough.
at
different how
food
interproximal
margin. Height
the man
represent B,
37
MAN
A m:,escel,m
m 4
Fig.
PRIMITIVE
force method
was different
attachment (From
ages
of
primitive the
gingival
kept ages, Begg,
of tooth. P.
teeth
and
remained
free
(A
trough
small to
the
man by
interproximal
the
interproximal
to
B)
C, Interproximal R.:
Am.
J.
Orthod.
1945.)
Civilized man’s dentition is pathogenic. It contracts diseases, dental caries, and periodontitis in the stagnation regions protected by plaque. The sites of these stagnation regions (namely, proximal surfaces and occlusal pits and fissures) were pointed out by G. V. Black. Because of their lack of knowledge of Stone Age attritional occlusion, univer.. sity dental research workers are not aware that plaque formation is caused by the absence of abrasive and cleansing properties in civilized man’s food. When they realize this true cause of plaque, it should be useful to them in discovering means to prevent both dental caries and periodontal disease. In Stone Age man proximal attrition wore away the contact points of his teeth and turned them into flat, continually enlarging contact surfaces. The process of mesial migration kept his teeth in proximal contact as their mesiodistal widths were being continually reduced. Consequently, the interdental space remained small and frequently became smaller as the teeth continually erupted. In civilized man the triangular interproximal space, as portrayed in Fig. 29, becomes gradually larger with age in the absence of tooth attrition. The apex of this space is the point of contact of the neighboring teeth, and the walls of the neighboring teeth comprise the two sides. The base is defined by the transseptal fibers. This pyramidical interproximal space continually enlarges in civilized man as the teeth erupt and the transseptal fibers move toward the necks of the teeth. The interdental papilla continues to proliferate ; however, the space finally becomes so large that the papilla can no longer fill it. This unnatural interdental space in civilized man, continually increasing in
Am. J. Orthod. January 1977
size, is a stagnation region where plaque forms and is protected from dislodgmcnt by sheltering of the walls of the teeth and the papilla. Reduction of the mesiodistal widths of adults’ teeth can eliminate existing interproximal periodontitis. Simultaneously, small areas of recurrent dental caries at the gingival margins of proximal fillings are eliminated. Mention of this ability to prevent caries and periodontal disease by simulating tooth attrition has been made here to draw to the attention of the dental profession as a whole the fact that advances can and must be made in other branches of dentistry through the application of knowledge gained from studying Stone Age attrition. For instance, proximal fillings should have flat contact surfaces. Original tooth widths should not be increased by restorations, as this may cause periodontitis, interproximal caries, and increased tooth crowding. Fixed bridgework is limited in the number of years of service because its mesiodistal length is not continually reduced and the abutment teeth cannot migrate mesially at different rates. Normally the posterior teeth must migrate farther and, therefore, travel at a greater rate than the anterior teeth. Also, because of continual tooth eruption, the entire bridge moves occlusally and the abutment teeth develop unfavorable clinical crown/root ratios. This results in reduced alveolar support and the teeth become more susceptible to occlusal and lateral stresses. Therefore, the abutment, teet,h become mobile and the bridge, as well as the supporting teeth, must be removed to avoid accelerated alveolar loss from periodontal disease and ultimate exfoliation. Simulation of attritional occlusion’s relatively flat occlusal plant and cdge-toedge anterior tooth relationships would add greatly to complete denture stability. Flat occlusal surfaces with relatively sharp edges have long ago proved to be the most efficient masticatory apparatus. Unworn cusps and fossae have no more place in artificial dentures than they do in the natural adult dentition. The lateral forces created by cusps are unnecessary and may actually bc a contributing cause of denture instability. A recent article’” indicates that progressive minds in other branches of dentistry are beginning to examine attrit,ional occlusion as a guide to both diagnosis and treatment planning. Drs. H. 3. Cooperman and 8. B. Willard studied the attritional planes of occlusion of Eskimos, Australian aborigines, Mexican Indians, Zulus, and Europeans. They noted the reduction in the curve of Spee, the absence of cusps, the loss of incisal edges and anterior overbite, and the forward position of the mandible. On the basis of this study, they have outlined a method to determine the correct (attritional) occlusal plane for each patient from landmarks on an upper model. They believe that the use of this plane can aid in diagnosis, increase stability, and simplify denture construction and oral reconstruction. Summary
Knowing how to execute differential force treatment with the proper appliances gives the orthodontist a great advantage, and treatment of any type of malocclusion, including mutilated cases and those not requiring reduction of tooth substance, becomes simple. In order to derive such benefits from the differential force technique, one
Volume Number
71
Differentin
1
force method
39
must use it exclusively and not attempt the simultaneous use of other methods, which leads to confusion in both diagnosis and appliance design. It is absolutely necessary to use the cold-drawn, heat-treated, highly resilient wire as produced especially for this method by A. J. Wilcock of Australia. Failures are caused by the use of other wire. The knowledge gained from the study of Stone Age attritional occlusion must be applied as much as is possible during orthodontic treatment. It will affect the diagnosis, amount and method of tooth mass reduction (if indicated), and final positions of teeth for maximum stability and esthetics. To date the differential force method is the only orthodontic technique that was developed to fit the true biologic requirements of man. The practice of the other branches of dentistry must also be related as nearly as possible to the principles found in the natural evolutionary development of man’s dentition, as found in his Stone Age attritional occlusion. To date we have, in orthodontics, the light wire differential force treat,ment method which is in accordance with this principle. The future must bring similar changes in many other branches of dentistry and, it is hoped, even more in orthodontics. REFERENCES
1. Begg,
P. R.: Progress report of observations on attrition of the teeth in its relation to and tooth decay, Aust. 5. Dent. 42: 3X-320, 1938. Begg, P. R.: Stone Age man’s dentition, AM. J. ORTHOD. 40: 298-312, 373-383, 462-475, 517-531, 1954. Begg, P. R.: Differential force in orthodontic treatment, AM. J. ORTHOD. 42: 481-510, 1956. Kesling, H. D.: Have recent technical advances in orthodontics made possible successful treatment for more people8 Dent. Clin. North Am., pp. 821-829, November, 1960. W. B. Saunders Company, Philadelphia. Begg, P. R.: Light arch wire technique, AM. J. ORTHOD. 47: 30-48, 1961. Kesling, P. C. (editor) : Begg J. Orthod. Theory and Treatment, July, 1962; April, 1963; September, 1964; January, 1968; June, 1969. Begg, P. R., and Kesling, P. C.: Begg Orthodontic Theory and Technique, ed. 1, Philadelphia, 1965, W. B. Saunders Company, pp. 5-51. Begg, P. R., and Kesling, P. C.: Begg Orthodontic Theory and Technique, ed. 2, Philadelphia, 1971, W. B. Saunders Company, pp. l-57. Enoki, K.: Begg light wire technique, Jap. Dent. Rev., pp. l-27, January, 1964. Motohashi, K., Ohno, T., Shimizu, K., Shimoyama, K., Yamamoto, Y., and Ohtsuka, E.: Eight teeth extraction cases treated wit,h the Begg technique, .J. Jap. Orthod. Sot. 32: 321-343, 1973. Begg, P. R.: Some aspects of the etiology of malocclusion of the teeth, unpublished thesis presented by P. R. Begg to University of Adelaide, 1935. Payne, G. S.: The effect of intermaxillary elastic force on the temporomandibular articulation in the growing macaque monkey, Am J. ORTHOD. 60: 491-504, 1971. Cooperman, H. N.: HIP plane of occlusion in oral diagnosis, Dent. Survey 51: 60, 62, 1975.
pyorrhea 2. 3. 4.
5. 6. 7. 8. 9. 10.
11. 12. 13. Dr. Dr.
Begg: Kesling:
North Terrace Orthodontic
(5000) Center
(46391)
