American Journal of ORTHODONTICS Volume
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,
and Westville, Ind.
wish to learn but few the price will pay. 3uveua1, first century A.D.
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
1. Tree gtment
and lower upper left fir st permanent
havi e previc susiy
differential anterior left were in the
is, from of the
subsi &a rice treatec
anI d lower
hint of re lative teeth right rc tcords
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
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
before of nonextraction
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.
3, B to
3 was patient
is Class teeth.
as is normally
E to G. E, Occlusal
this 1 and and
a reduction direct
Am. J. O?%hod. January 1977
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,
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-
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.
whose treatment casts desirable repositioning
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
4, B and
C. B, Views
of the incisor anterior
from angle 1.
4, D and
a total positioner
E. D, The
foreshortened at the of
at that in
crowns view This and
because patient’s two
posterior while central lingual required The
inclinations. 26 patient
arches were at
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
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.
4, H and
molars righting I, Arch positioner
auxiliaries form after
Occlusal position during
made any 3
Detailed to their
months’ finishing axial
of from duration was
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~(*(~.
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
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
and clusion this in two
marked because patient
contact first time
a Class of
the five third
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
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 :
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
wires actually used the Class II, Division
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.
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
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.
gingiva from too
from The the
B, Level of
relative of gingival
kept ages, Begg,
of tooth. P.
C, Interproximal R.:
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
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
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.
North Terrace Orthodontic