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Bone changes resulting from experimental orthodontic treatment
Abstract
While various experiments had been performed in the past to determine the nature of tissue changes as the result of applied forces, we still felt that the whole question regarding the extent of tissue involvement and its behavior to the forces used in orthodontic treatment was very much in an empiric state. A series of experiments was instituted, therefore, in which typical methods of orthodontic treatment were employed, the changes noted clinically, and the animals subsequently sacrificed for a careful histologic study. The animal used was the Macacus rhesus. Two standard methods of treatment for Class II malocclusions were used; one, intermaxillary pressure by means of rubber bands and the other, jumping the bite. In histologic study the alveolar bone surrounding the posterior teeth, the angle of the jaw, and the temporomandibular joint were all studied. Changes were found in all of these regions to indicate, through the evidence of apposition and resorption, that the forces applied resulted not only in a mesial movement of the posterior teeth but also to indicate a reorientation of the position of the body of the mandible by a change in the angle of the jaw and changes in the form and position of the condyle head and glenoid fossa. To determine whether these changes were due entirely to the forces applied, an additional experiment for verification was performed in which the forces applied were as if for treatment of Class III malocclusion. These forces were, therefore, in an opposite direction and the findings showed changes directly opposite in direction to those applied in treatment of Class II malocclusion.Because of the changes observed at the angle of the jaw and the temporomandibular joint, a method is suggested to correct cases of Class II malocclusion by means of forward movement of the body of the mandible without movement of the teeth in the mesial direction from their alveoli.
... (Am J Orthod Dentofacial Orthop 2009;135:737- 48) R emodeling changes in the condylar head and the glenoid fossa have been reported after functional appliance treatment for correction of Class II skeletal dysplasia with mandibular retrognathia. [1][2][3][4][5][6][7][8][9][10][11][12] The posterior displacement of the condylar head and the anterior relocation of the glenoid fossa have been recorded radiographically on serial cephalograms. 13,14 Computed tomography scans have shown a double contour on the bony outline of the condylar head and the fossa articularis. ...
... Histologic and radiographic evidence points toward remarkable changes in this posterosuperior region after anterior mandibular advancement. [1][2][3][4][5][6][7][8][9]20,21 This finding is supported by those of Kantomaa et al 47 and Kantomaa and Perttiniemi, 18 who concluded that reduction in functional stresses in rats led to increased proliferation in the condylar cartilage posterosuperiorly. Moss 46 quoted the Heuter Volkmann law to explain why the condylar cartilage responds to mandibular advancement. ...
This study was designed to evaluate patterns of stress generation in the temporomandibular joint after mandibular protraction, by using a 3-dimensional finite element method. The results of the initial investigation are reported here in Part 1. The effects of varying the construction bite are reported in Part 2.
A 3-dimensional computer-aided design model was developed from the magnetic resonance images of a growing boy (age, 12 years), by using I-DEAS NX (version 11.0, Siemens PLM Software, Plano, Tex). The model simulated mandibular protraction, with 5 mm of sagittal advancement and 4 mm of vertical opening. Stress distributions on the condylar neck, the glenoid fossa, and the articular disc in the anteroposterior and mediolateral directions were assessed.
Tensile stresses were located on the posterosuperior aspects and compressive stresses on the anterior and anterosuperior aspects of the condylar head. Tensile stresses were found in the posterior region of the glenoid fossa near the attachment of the posterior connective tissues.
These results suggest that, on mandibular protraction, the mandibular condyle experiences tensile stresses in the posterosuperior aspect that might help explain condylar growth in this direction. Similarly, on the glenoid fossa, tensile stresses are created in the region of posterior connective tissues; this might be correlated with the increased cellular activity in this region. Further study with variable vertical heights of the construction bites is needed.
... According to the experimental studies, the glenoid fossa and the head of the condyle exhibit remodeling changes as a result of intermaxillary traction (with class II elastics). However, these changes are not significant enough to solve the skeletal discrepancy [15][16][17]. Class II elastics serve as a functional appliance and an orthodontic device that can extend the mandible by promoting growth and increasing the amount of condylar cartilage [18]. Nonetheless, the majority of clinical research indicates that Class II elastics mostly have dentoalveolar effects [19], [20]. ...
ABSTRACT
Intermaxillary elastics is used as a therapeutic method for treatment of the skeletal class II malocclusion because of its skeletal and dentoalveolar effects similar to those of functional appliances. However, the dental side effects prompted researchers to strenghthen the anchorage in order to overcome these side effects, especially after the spread of skeletal anchorage devices. The aim of this study is to evaluate the skeletal and dentoalveolar changes resulted from using class II intermaxillary elastics in combination with indirect skeletal anchorage. The sample consisted of 17 growing patients with skeletal class II malocclusion caused by mandibular deficiency. They would have permanent dentition or at the end of mixed dentition. All the patients treated with Class II elastics supported by miniscrews indirectly. cephalometric radiographs were taken just before and after mandibular advancement (T1 and T2 respectively). It was found by studying cephalometric radiographs that using class II elastics in combination with indirect skeletal anchorage by miniscrews caused forward movement of the mandible and increasing in its length. It also resulted an acceptable proclination of lower incisors and extrusion of the lower molars.
... 29 However, some animal studies have shown that condylar and glenoid fossa modeling could also be accomplished by OE use. [30][31][32] To the best of our knowledge, no studies have been reported on the effects of the elastic forces on the TMJ structures. To study the possible relationship between the OE forces and TMJ biomechanics, we constructed a finite element model (FEM) of the TMJ. ...
Purpose:
The purpose of the present study was to evaluate the effects of the orthodontic elastic forces used in fixed orthodontic treatment on the temporomandibular joint (TMJ) with normal and anteriorly displaced discs.
Materials and methods:
Four different computer models for Class II and III malocclusion with the TMJ disc in the normal and anterior position were created. All the models were subjected to a constant force of 200g (125 N) on both sides to simulate the elastic pull force placed between the upper and lower jaw with 2 different configurations. Stresses on the TMJ were evaluated using finite element analysis.
Results:
The stresses in both the condyle and the disc were greater in the Class II models than in the Class III models. Similar results were found between the groups according to the direction of the orthodontic elastics. In the Class II models, the peak value of the maximum principal stresses was located in the posterior region of the condyle in the models with disc in the normal position.
Conclusions:
The elastic forces used during fixed orthodontic treatment increases the stress on the TMJ, especially for Class II patients. If the disc is in an anterior position, the stresses could be more harmful to the retrodiscal tissue. Thus, during orthodontic treatment, the TMJ should be carefully assessed to avoid irreversible damage.
... It thus seems that as the growth of the condyle is adaptive at least as far as direction is concerned, and it tends to maintain its original position in relation to the fossa. This assumption seems to be in agreement with the earlier findings about the adaptive growth of the condyle, when the mandible has been rotated (Breitner, 1941). Rotation of the mandibular position, for instance posteriorly, results first in an increase in the angle between the articulating surface of the fossa and the condyle, which leads to a more posteriorly directed condyler growth. ...
... Breitner 3 foi o primeiro a demonstrar, histologicamente, o efeito do avanço mandibular no crescimento condilar em um primata na fase de crescimento. Férulas foram desenhadas para criar planos inclinados que forçavam a mandíbula para anterior ao ocluir. ...
Analysis of the changes in the temporomandibular joint morphology induced by mandibular advancement with the Herbst appliance
The aim of the present study was to conduct a literature review addressing the adaptive changes of the temporomandibular joint induced by mandibular advancement with the Herbst appliance. An attempt was made to discuss the experimental investigations performed in animals with utilization of different methodologies, as well as clinical trials in humans employing different diagnostic imaging methods. Regardless of the study design, it seems clear that remodeling changes occur on the joint surfaces, which are mainly characterised by bone apposition on the posterior and superior surfaces of the mandibular head, as well as bone neoformation on the articular fossa, at the anterior region of the postglenoid spine. These positive results are followed by absence of adverse alterations in the condyle, articular disk, fossa or eminence. However, some doubt remains as to the real mechanism in charge of remodeling of the condyle and articular fossa secondary to mandibular advancement.
Resumo O presente estudo tem o objetivo de reali-zar uma compilação dos principais artigos existentes na literatura, voltados para a investigação das alterações adaptativas na articulação temporomandibular, decorren-tes do avanço mandibular com o aparelho Herbst. Para tentar elucidar essas altera-ções, procurou-se discorrer sobre pesqui-sas experimentais realizadas em animais, sob diferentes perspectivas metodológicas, como também pesquisas clínicas realizadas em humanos, nas quais foram utilizados diferentes métodos de diagnóstico por ima-gem. Independente da natureza do estudo, Palavras-chave: Articulação temporomandibular. Aparelho Herbst. Remodelação óssea. parece evidente que ocorrem alterações remodeladoras nas superfícies articulares, caracterizadas, principalmente, por uma aposição óssea na superfície posterior e superior do côndilo e uma neoformação óssea na fossa articular, localizada na região anterior da espinha pós-glenóide. Esses resul-tados positivos são acompanhados por uma ausência de alterações adversas no côndilo, disco, fossa ou eminência articular. No en-tanto, alguma dúvida ainda persiste sobre o real mecanismo responsável pela remode-lação do côndilo e fossa articular frente ao avanço mandibular.
... Breitner credits Kingsley as the first to suggest placement of an appliance between the teeth to unlock the occlusion ("jump the bite") in Class II patients to take advantage of forward mandibular growth. 32 In 1967, Lager 19 introduced the term "compensatory dentoalveolar development" and recommended using a bite plate in growing Class II patients to eliminate occlusal interdigitation, allowing forward movement of the mandibular dentition and improvement in the anteroposterior relationship with mandibular growth. In 1980, Solow 22 suggested that the dentoalveolar compensatory mechanism is "a system which attempts to maintain normal inter-arch relations under varying jaw relationships." ...
During facial growth, the maxilla and mandible translate downward and forward. Although the forward displacement of the maxilla is less than that of the mandible, the interarch relationship of the teeth in the sagittal view during growth remains essentially unchanged. Interdigitation is thought to provide a compensatory (tooth movement) mechanism for maintaining the pattern of occlusion during growth: the maxillary teeth move anteriorly relative to the maxilla while the mandibular teeth move posteriorly relative to the basilar mandible. The purpose of this study was to investigate the hypothesis that the human chin develops as a result of this process.
Twenty-five untreated subjects from the Iowa Facial Growth Study with Class I normal occlusion were randomly selected based on availability of cephalograms at T1 (mean = 8.32 yr) and T2 (mean = 19.90 yr). Measurements of growth (T2 minus T1) parallel to the Frankfort horizontal (FH) for the maxilla, maxillary dentition, mandible, mandibular dentition, and pogonion (Pg) were made.
Relative to Pg (a stable bony landmark), B-point moved posteriorly, on average 2.34 mm during growth, and bony chin development (B-point to Pg) increased concomitantly. Similarly, the mandibular and maxillary incisors moved posteriorly relative to Pg 2.53 mm and 2.76 mm, respectively. A-point, relative to Pg, moved posteriorly 4.47 mm during growth.
Bony chin development during facial growth occurs, in part, from differential jaw growth and compensatory dentoalveolar movements.
Purpose of this study was to evaluate changes in the temporomandibular joint (TMJ) position after bilateral sagittal split osteotomy (BSSO) of the mandible by the help of pre- and postoperative cone-beam computed tomography (CBCT) images.
A collective of n = 78 patients was investigated between 2009 and 2011 before and after BSSO of the mandible in mono- or bimaxillary orthognathic surgery procedures. No intraoperative fixation of the condyles was administered. CBCT scans were performed in all patients before and immediately after surgery with the KaVo 3DeXam device in the position of terminal occlusion. Subsequently, all scans were analyzed by help of the eXam Vision program and the ImageJ image processing software. Alterations of the TMJs were quantified by determining pre- to postoperative differences of the intercondylar distance, the mandibular angle on both sides, and the condylar angles in the transversal plane.
The difference between pre- and postoperatively ascertained values was minimal (means: lateral condylar distance -0.17 mm; distance of condylar centers -0.32 mm; medial condylar distance -0.49 mm; left mandibular angle +1.06°; right mandibular angle +2.06°; condylar angles in relation to a reference line: left -2.93, right -0.75; angle of cutting +3.42). There is no apparent tendency toward a positional change in any of the 3 examined planes. Between bi- and monomaxillarily operated patients there was no difference either, except for the osteotomy plane.
A 3-dimensional analysis of CBCT data of the TMJ seems to be appropriate to determine the condylar position pre- and postoperatively. Performed by an experienced orthognathic surgeon, BSSO of the mandible does not effectuate any relevant changes of the TMJ-position, thus making an intraoperative condyle-fixation unnecessary.
In addition to studying the effectiveness and efficiency of removable acrylic plates in correcting anterior forced crossbite, the influence of outcome predictors were evaluated.
In all, 65 patients met the inclusion criteria of anterior forced crossbite, mixed dentition, removable plate treatment, and complete case documentation. Effectiveness was assessed based on pre- and posttreatment study casts (which were analyzed for successful treatment outcomes defined as ≥ 1 mm of overjet and overbite) and efficiency was assessed based on treatment duration and number of appointments. Potential outcome predictors were also evaluated, including age, gender, dental maturity, Angle Class, number of teeth in crossbite, severity of crossbite, overbite, ANB angle, Wits appraisal, mandibular plane angle, and patient compliance.
Successful crossbite correction was achieved in 48 of the 65 patients (74 %) within a median of 2.8 months and 2.0 appointments. Plate treatment was discontinued following another median of 11.6 months and 6.5 appointments. Promising outcome predictors are the number of teeth in crossbite (1-2 versus 3-4 teeth = success in 81 versus 42 % of cases), dental maturity (early versus late mixed dentition = success in 84 versus 52 % of cases), and Angle Class (I versus III = success in 83 versus 61 % of cases).
Removable acrylic plates were found to be moderately effective and efficient in correcting anterior forced crossbite. Children presenting with Angle Class I and crossbites involving not more than two teeth when treatment is started during the period of early mixed dentition had the best prognosis for treatment success.
Orthodontic tooth movement has an
inflammatory response and so evokes painwhich is the most unpleasant symptom which drives the patient to
seek medicaments. Analgesic drugs are commonly prescribed in day to day orthodontic practice to control pain
evoked by orthodontic forces. These drugs are also available as OTC ( over-the –counter) drugs and can be
bought from medical shops without prescription.
T he present investigation is done to study the effects of three different analgesic and anti-inflammatory
drugs, acetaminophen, ibuprofen and nimesulide, on the rate of orthodontic tooth movement in guinea pigs.
There are laws which govern the arrangement of the natural teeth. These laws are found to be constant in the teeth of animals as well as human beings.The inclination of the natural posterior teeth is governed by different factors from those which govern the pitch of the occlusal surfaces. The pattern of wear has a strong influence upon the pitch of the occlusal surfaces.Wear could be of a beneficial, physiologic nature up to a point.Function is an important factor of form.
The sole use of either molar crowns or anterior bite planes attached to anterior bands for opening the bite is not recommended. In combination, however, they are most satisfactory.The crown surfaces on the molars should be flat, not anatomic, and the bite planes attached to the anterior bands should be placed as nearly parallel (not inclined) to the occlusal plane as possible.Molar crowns and anterior bite planes are indicated in those cases which require that the bite he opened in order to relieve occlusal interference and to obtain individual tooth movements that would be limited or prohibited during the use of other methods of opening the bite.
Eight children were treated with the occlusal guide plane appliance. Several changes were consistently noted: (1) the posterior border of the mandible invariably returned to approximately its pretreatment position, (2) molar relationships were always changed from a Class II to a Class I occlusion in a short period of time, (3) the head of the condyle tended to return to a location comparable to the pretreatment position in every case, and (4) relative mandibular prognathism was not increased statistically or clinically by this method of treatment.This study is not intended for the purpose of propagating a particular appliance. The treatment periods listed do not necessarily denote a finished orthodontic result; however, several cases were treated to an acceptable occlusion in less than six months.One may speculate that anterior development of the mandible may have been slightly stimulated in several cases. The lack of anterior development of the mandible in the remaining cases suggests that very desirable results can be produced in selected patients, even though skeletal proportions are not changed. Future investigations on laboratory animals may provide more concrete evidence for the basis of final conclusions.
Zusammenfassung In einer tierexperimentellen Studie an Affen der Spezies Cercopithecus aethiops, die sich im maximalen Längenwachstum befanden, wurden Vor-, Rück- und Seitverlagerungen des Unterkiefers durchgeführt und die Veränderungen im Kiefergelenk durch histologische und fluoreszenmikroskopische Untersuchungen belegt.
Differently enabled functional movements of the mandible and different types of maxillomandibular and occlusal relations may share a cause-and-effect relationship with the disorders affecting the temporomandibular joint (TMJ). The purpose of this article is to draw inferences with orthodontic implications for the TMJ from an overview of adverse factors for growth and biomechanics of the TMJ, dentofacial characteristics associated with temporomandibular disorders, and mechanism of action of orthodontic interventions affecting the TMJ. Inferences drawn include the importance of history taking, functional evaluation and the need for radiological evaluation of TMJ condyle and disk, and position and function during procedures that are expected to interfere with TMJ homeostasis, for example, surgical craniofacial corrective procedures, functional therapy, and occlusal reconstructive procedures. Extremes of form (eg, excessive overjet and overbite, open bite and deep bite, skeletal hyperdivergence and hypodivergence) and differently enabled mandibular functions resulting in overloading of TMJs are all potential factors in the etiology of its disorders, thus enhancing the need for its evaluation before, during, and after treatment; a reciprocal relationship exists between growth and biomechanics of the TMJ, dentofacial characteristics and articular afflictions, occlusion and TMJ, and mandibular movements and TMJ. These interrelated, interdependent, and/or coexistent factors have a bearing on the diagnosis and treatment of the disorders of the TMJ. Orthodontic therapy should be directed to achieve a structural balance to facilitate physiologic adaptation and rehabilitation. Because the movements of the mandible are not restricted by the joint structure per se, other operative templates, for example, neuromuscular and psychological, apart from the structural template, contribute significantly to its complex functions and pathology. There is a need to find optimum values of structure and function of the masticatory system and develop mechanisms that can record and reproduce highly accurate geometric models of a subject's TMJ and teeth combined with recordings of chewing trajectories and 3-dimensional TMJ movements to obtain subject-specific models of masticatory system by either improving upon conventional mechanical articulators or by application of virtual-reality techniques for the development of virtual articulators for diagnosis and treatment of the disorders of masticatory system.
Articular cartilage can proliferate sufficiently to alter the contours of joints, allowing them to adapt morphologically to various mechanical stresses. This remodeling has been classified into three types based on histologic criteria which were then applied to the temporomandibular joint. This joint has a fibrous type of articular tissue which is converted postnatally into fibrocartilage in the loaded areas. The thickness and cell population of this tissue, and the amount of internal reconstruction in the subchondral bone vary from one part of the joint to another. These changes appear related to the distribution of mechanical stresses in the joint. Conclusions drawn are: The temporomandibular joint shows the following remodeling trends: progressive remodeling on the anterior part of the condyle, medial part of the tubercle, and roof of the mandibular fossa; regressive remodeling on the posterior part of the condyle and on the lateral part of the tubercle. A perforation in the disc causes progressive remodeling on the condyle and regressive remodeling on the tubercle at the perforation site. Articular remodeling merges gradually into osteoarthritis as the articular tissue breaks down. The net effect of remodeling that has become uncompensated or pathologic is: condyle flattened and enlarged, tubercle resorbed, disc perforated, and articular surfaces uneven. If the dentition is not restored or replaced, a high rate of temporomandibular remodeling occurs which will probably continue into osteoarthritis.
Aus zahlreichen Literaturhinweisen, klinischen Beobachtungen und den Ergebnissen eigener experimenteller Untersuchungen haben wir Argumente fr eine Theorie gewonnen, nach der die Funktion Bedeutung fr den vertikalen Gebiaufbau besitzt.From many references in the literature, clinical observations and the results of our experimental investigations a theory was developed indicating that function is an important factor for the vertical development of the jaws.De nombreux exemples bibliographiques, des observations cliniques et les rsultats de recherches personnelles ont permis l'auteur d'tablir une thorie selon laquelle la fonction joue un grand rle dans l'dification verticale de l'occlusion.
1.1. Evidence has been presented that the force of eruption is not the primary factor in increasing the dental height or the vertical dimensions of the jaws.2.2. Instead, growth in the length of the ramus causes the mandible to recede from the maxilla, thereby increasing the intermaxillary space.3.3. During approximately the first five years of life, the downward growth of the temporal bone contributes to the lowering of the mandible.4.4. When an intermaxillary space is established, the ramus-growth-length is slowed or retarded and the clinical eruption of teeth along with the vertical growth of the maxilla and of the body of the mandible occurs.5.5. This complementary manner of growth of adjacent parts or growth by spatial interrelation is a recognized biologic phenomenon.6.6. Lack of growth in ramus-length will produce a characteristic series of growth disturbances: 6.1.a. The intermaxillary space fails to increase.6.2.b. The teeth cannot erupt and remain submerged, their roots growing normally but deeper within the jawbone.6.3.c. The vertical dimensions of the maxilla and of the body of the mandible fail to increase.6.4.d. The anterior teeth continue in eruption resulting in an overbite relation.6.5.e. The anterior overbite relation will inhibit the forward growth of the anterior part of the mandible.7.7. The ramus-growth-length is therefore regarded as the “pacemaker” for the normal growth and development of the dental mechanism or the lower face.8.8. There is no direct cause and effect relation between the growth and development of the jaws and the growth and development of the teeth.9.9. There is a factor of spatial interrelation between the growth of the jaws and the clinical eruption of the teeth.10.10. Early recognition of an unduly delayed growth in ramus-length may prevent the development of a group of malocclusions.11.11. It is believed that the retardation of growth in ramus-length is due to a metabolic factor.12.12. The extent of duration of the accelerated growth intervals of ramuslength should be further studied.
An infant affected with Pierre Robin's syndrome of micrognathia was treated orthopedically at the age of 2 months. After five months of therapy, normal jaw relations were established. The child died of other causes at the age of 9 months. The histologic analysis of the temporomandibular joint revealed the following: 1.1. The temporal structures of the joint gave evidence of an orthopedically induced transformation in the sense of a forward displacement of the fossa by coordinated processes of bone apposition and bone resorption.2.2. Absence of traumatic injuries of the capsular structures was noted.3.3. The condylar head showed growth activity in the vertical and horizontal directions exceeding the normal rate.4.4. These histologic peculiarities are identical with those described by Breitner, Häupl, and Hoffer in similarly treated experimental monkeys.These observations lead to the following conclusions: 1.1. The scope of orthodontic treatment is not necessarily limited to transformations of the periodontal structures of the jaws. Even parts of the temporal bone may be influenced by orthodontic appliance therapy.2.2. X-ray analysis does not reveal the entire picture of orthodontically induced growth changes. Animal experimentation remains an important aid for the bioassay of orthodontic therapy.3.3. Häupl's functional jaw orthopedics takes best advantage of the morphogenetic property of functional stimuli (Roux21), although any other appliance system may produce the same effect.
Current orthodontic literature reiterates the contention that the inherited growth pattern determines the form of the human jaws and that the jawbones therefore cannot be modified or influenced. According to this contention, effective influence of any treatment is restricted to the alveolar bone. (Brodie, Broadbent, Hellman, Thompson, Mershon, Jackson.) The acceptance of this concept limits improvement in orthodontic therapy to the perfecting of mechanical, tooth-moving devices. More important, if the concept is fallacious, it precludes (if accepted) any clarification of the origin of dental and facial malformations. Because of the inherent defeatism of this contention of immutability, any contradictory theory deserves attention.Generally accepted biologic laws do not support the validity of the theory of immutability of the jawbones (Roux, Darwin, Russel).Through decades orthodontic research has favored the idea that extraalveolar areas can be influenced by treatment (Angle, Case, Baker).Moreover, histologic proof has been published11 of bone transformations induced in areas other than the alveolar process, such as the temporomandibular joint, ramus, angle and lower border of the mandible.There remains a contradiction between, on one side, general biology and these findings and, on the other side, the conception of immutability of the jawbones.The clarification of this issue is fundamental to the understanding of the origin of dentofacial malformations as well as to improvement in the methods of their correction.In this essay new, clinical proof is added to previously published microscopic evidence that bone changes can be induced in extra-alveolar areas.In a mature Macacus rhesus monkey a complete and lasting change in occlusal relations was created without applying any forces to the teeth or to the alveolar process. No mechanical device was used but, by paralyzing masticatory muscles and thus disturbing the balance between muscular forces and the given resistance of the skeleton, an Angle Class III malocclusion was created in a previously normal animal within seventy-two days. This malocclusion has persisted for one year and a half to date, long after recuperation of the affected muscles.In a similar animal an Angle Class II malocclusion, with the associated anomalies of excessive overjet and overbite, was created by raising the bite through flat caps in the molar and premolar regions. The development of this Class II may be correlated with the first experiment where a Class III was created through weakening of the masticatory muscles; for raising the bite means strengthening (increased tone) through elongation of those same masticatory muscles whose weakening induced the Class III anomaly in the first experiment.The results of the experiments are significant in reference to the following pointsThe experiments corroborate previously published histologic evidence of induced extra-alveolar bone transformations.The experiments suggest one possible cause of dental malformations, namely, a disharmony among the muscular forces, or between muscular forces and the architecture of the bone.The experiments point toward a possible means of influencing the occlusion without employing appliances or similar conventional apparatus, by directly modifying muscular strength or bony resistance, possibly even by influencing systemic factors.The experiments elucidate the necessity, in attempting improvement of orthodontic therapy, not of concentrating upon mechanical devices but rather of seeking means of modifying the skeleton.
The main reason for almost universal adherence to the principle of fixation in the treatment of fractures is suspected to be the lack of an individually adequate measure of movement. It is shown that, on the basis of distinguish ing between functional and mechanical stimulation, it is possible to impart to the fragments a repeated passive movement which is determined not so much by arbitrary interference as by the patient's individual constitution. A description of the orthopedic system used (summary of Part II) precedes the general discussion of its applicability to the treatment of fractured jaws.
The connective tissue fibers with which we are concerned in orthodontic tooth movement have been defined, and their functions have been described.The histologic findings of prominent research workers, showing that these fibers were persistent and resistant to control, were reviewed.Clinical observations were recalled to indicate evidence of the force of these fibers, and the possibilities of their effect upon tooth repositioning were noted.The confining, or limiting, connective tissue fibrous band theory was proposed as a supplement to the basal bone and muscle balance theories. Explanations of relapse were described in the light of the potential persistence of this connective tissue band around the necks of the teeth.It was pointed out that the connective tissue fibers must be capable of tooth movement and that they might restrain other movements.It was suggested that, theoretically, these forces might be neutralized by various methods, but no specific method was advocated.
Histologic investigation of experimentally moved deciduous and permanent teeth and their surrounding tissues reveal:Orthodontic movement of teeth of the deciduous or mixed dentition produces migration of underlying and adjoining tooth germs. This is made possible by bone resorption and deposition. Hence orthodontic treatment in the deciduous dentition can affect the development of the permanent successors.The direction in which tooth germs move corresponds to the direction taken by the roots of the adjacent erupted teeth. Therefore movement of the roots of these teeth in the proper direction is essential.Displacement of the roots of teeth in the same direction as their crowns are shifted is assured only if tipping movements are avoided. Where tipping appliances must be used observation of the following rule may help to keep the center of rotation near or at the apex: “Use weak forces, applied near the gingival margin, in a pulling manner and in a direction never pointing toward the root.”
Previous histologic investigations of experimentally treated animals have furnished evidence that the influence of orthodontic treatment is not limited to the alveolar processes but extends to other areas, causing bone transformations in the temporomandibular joint, ramus, body and angle of the mandible.In an effort to determine the relation of these extra-alveolar bone changes to changes in the occlusion, a new series of experiments has been conducted.Various experiments are described in which an artificial change of the vertical dimension was attempted. These experiments, as well as those previously reported, show that attempted changes in the vertical dimension encourage extra-alveolar bone transformations in addition to those in the alveolar processes.Almost all occurring bone transformations can be explained if we assume that artificially elongated muscles tend to re-establish their original length, and succeed in attaining it by adaptation of the bone.The vertical dimension of a given individual appears to be the result of an equilibrium among all forces (active and resisting) present in the masticatory apparatus. The vertical dimension can therefore be permanently decreased by mutilation of the hard tissues, but it cannot be permanently increased above its original value (except, perhaps, by weakening of muscular tissue).The forces created by raising the bite are probably transmitted to extra-alveolar areas by increased resistance (adaptation) of the alveolar bone to excessive stress in a direction parallel to the long axis of the tooth. Raising the bite artificially will therefore cause bone transformations within and without the alveolar processes, with the ultimate result of re-establishing the original muscular length and the original vertical dimension. The bone transformations necessary to re-establish the original vertical dimension might possibly be utilized for various orthodontic purposes, such as influencing the facial contours, or closure of open-bite.The exploitation of changes within the alveolar processes produced by various appliances has long been the basis of orthodontic treatment. The results of the experiments encourage the attempted exploitation of extra-alveolar bone changes as well.
1.1. This article presents a method for completing some difficult deep overbite cases.2.2. The selection of cases reduces itself to the following situation, whether acquired by nature or by preliminary orthodontic treatment: (a) buccal segments in neutroclusion, (b) maxillary incisors spaced and protrusive, (c) mandibular incisors striking the lingual surfaces of the maxillary incisors, and (d) mandibular curve of Spec flattened.3.3. The mechanics of this method was described by fully explaining its use in the treatment of a typical case.4.4. The construction details were outlined.5.5. Advantages and disadvantages were discussed.
Application of an incisal bite plane for as little as three d caused a significant increase in the size of the sublingual glands of rats, with some evidence of hyperplasia and hypertrophy of the acinar cells. The enlargement had few effects on salivary secretion, and the gland changes were reversible.
The objective of this study was to determine if variation in the shape and mineralization of the mandibular condyle are the result of natural adaptation in response to different functional loading demands. Eight female Kuni Kuni piglets were randomly assigned to two groups of four, receiving either a soft or hard diet. Each animal was given three separate doses of vital stains intravenously at set time points during the study. At 8.5 months, animals were euthanized and temporomandibular joints (TMJs) were excised. Histological analysis was used to measure the amount of new bone deposition in the anterior, central, and posterior regions of the mandibular condyle. Backscatter electron (BSE) imaging was used as a semiquantitative estimate of bone mineralization in these two diet groups. Histology revealed that the degree of new bone deposition in the hard-diet group was significantly (n = 4, P < 0.001, paired t-test) higher than that of the soft-diet group. Also, the majority (87%) of animals fed a hard diet tended to show greater new bone deposition on the leftside in comparison to the right, indicating a chewing preference for the left side. In both groups, the degree of new bone deposition was significantly (P < 0.01) higher in the posterior area than in other regions. BSE imaging corroborated basic histology results, with significantly (P < 0.01) higher mineralization levels detected in the hard-diet group. These findings indicate that diet consistency has a small but significant effect on the rate of bone deposition in the mandibular condyle.
ZIEL: Untersuchung des kurz- und langfristigen Einflusses der Herbst-Behandlung auf die totale, matrix und intramatrix Rotation des Unterkiefers (Björk und Skieller 1983) bei hypo- und hyperdivergenten Klasse II Patienten.
MATERIAL: 17 hypodivergente (ML/NSL <= 26) und 13 hyper-divergente (ML/NSL >= 37) Klasse II Patienten, die mit der Herbst-Apparatur behandelt wurden.
METHODE: Auswertung von Fernröntgenseitenbildern des Kopfes von vor und nach 7-monatiger Herbst-Behandlung sowie 5 Jahre nach der Behandlung (Methode von Björk und Skieller, 1983).
BEFUND: Behandlungsveränderungen: In der hypo- und hyperdivergenten Gruppe lag eine leichte (n.s.) anteriore totale Unterkieferrotation (0,3° bzw. 0,1°) vor. Bedingt durch eine anteriore intramatrix Rotation (0,88° bzw. 0,46°) war die matrix Rotation in beiden Gruppen posterior (hypo 0,5°; p<0,05; hyper 0,4°; n.s.). Veränderungen nach der Behandlung: In beiden Gruppen lag eine (0,01 kleinerals p<0.05) anteriore totale Unterkieferrotation (hypo 2,3°, hyper 1,3°) vor. Bedingt durch eine posteriore intramatrix Rotation (0,13° bzw. 0,60°) war die matrix Rotation in beiden Gruppen anterior (hypo 2,4°; p<0,001; hyper 1,9°; p<0,05). Es lag kein Gruppenunterschied vor.
FOLGERUNG: Die während des natürlichen Wachstums anteriore totale Rotation des Unterkiefers wurde während der Herbst-Behandlung nicht beeinflußt. Durch Umbauprozesse am Unterrand der Mandibula (intramatrix Rotation) war aber eine posteriore matrix Rotation zu finden. Durch einen reversiblen Umbau nach der Behandlung änderte sich die matrix Rotation nach anterior. Die Veränderungen waren bei hypo- und hyperdivergenten Patienten vergleichbar.
AIM: To assess the short- and long-term influence of Herbst treatment in high- and low-angle Class II malocclusions with respect to total, matrix and intramatrix rotation of the mandible (Björk and Skieller,1983). SUBJECTS: 13 high-angle (ML/NSL >= 37) and 17 low-angle (ML/NSL <= 26) Class II malocclusions treated with the Herbst appliance.
METHOD: Analysis of lateral headfilms from before and after 7 months of Herbst treatment as well as 5 years posttreatment by superimposition of the radiographs on stable bone structures of the mandible and the anterior cranial base (Björk and Skieller,1983). Three types of mandibular rotations were assessed: (1) Total rotation: change of a constructed implant line (IL) in the mandibular corpus relative to the anterior cranial base, (2) Matrix rotation: change of a tangential mandibular line (ML) relative to the anterior cranial base, (3) Intramatrix rotation: change of IL relative to ML.
RESULTS: Treatment changes: In both the high- and low-angle group insignificant anterior total mandibular rotation occurred (0.1° and 0.3° respectively). Due to mandibular lower border remodeling (intramatrix rotation) matrix rotation was posteriorly directed (high-angle 0.4°/ n.s.; low-angle 0.5°/ p<0.05). Posttreatment changes: In both the high- and low-angle group significant (0.05>p>0.01) anterior mandibular rotation was recorded (1.3° and 2.3°, respectively). Due to mandibular lower border remodeling (intramatrix rotation which was opposite to that seen during treatment) matrix rotation was anteriorly directed and larger than total rotation (high-angle 1.9°/ p<0.05; low-angle 2.4°/ p<0.001). No statistical differences were found between the two examination groups.
CONCLUSION: During Herbst treatment almost no total mandibular rotation was observed. However, due to mandibular lower border remodeling posterior matrix rotation resulted in both high- and low-angle subjects. On a long-term basis posttreatment, a significant anterior total and anterior matrix rotation of the mandible occurred in both high- and low-angle subjects. All components of rotation were tendenciously larger in the low-angle subjects.
Submitted in partial fulfillment of the requirements for a Certificate in Orthodontics, Dept. of Orthodontics, University of Connecticut Health Center, 1977
The British Orthodontic Society invites outstanding contributors from the field of Orthodontics to give the guest lecture in memory of George Northcroft. In 2007 the guest lecturer was Professor Murray C. Meikle. The article that follows was presented as the Northcroft Memorial Lecture 2007 at the British Orthodontic Conference, Harrogate, UK, 24th September 2007.
The purpose of this work was to provide a comprehensive description of craniofacial alteration in the Class III patient in response to orthopedic chin cup treatment. Thirty patients with skeletal Class III malocclusion under treatment with the chin cup appliance, averaging 6 years of age at the start of treatment, were followed longitudinally for a 3-year period. This treatment sample was compared cephalometrically with an analogous untreated Class III sample.The following significant craniofacial alterations were noted in the sample that underwent orthopedic chin cup therapy: 1.1. A retardation of vertical ramus growth.2.2. A retardation of vertical development in the posterior aspect of the mandibular body.3.3. A retardation of vertical development in the posterior maxilla.4.4. A closure of the gonial angle.5.5. A distal rotation of the mandibular complex.6.6. A decreased amount of anteroposterior anterior cranial base growth.7.7. A redirection of the predominantly horizontal mandibular growth pattern to a more vertical direction.8.8. A reduction of the maxillomandibular malrelationship toward normative values.9.9. A production of an Angle Class I dental relationship following the establishment of normal maxillomandibular relations.10.10. A lack of detectable localized effect on the symphyseal region or incisor position as a direct result of chin cup placement and pressure.11.11. Development of soft-tissue profile changes in harmony with underlying skeletal changes.While all of the listed alterations are important when analyzed separately, they gain increased importance when considered together. With orthopedic chin cup therapy, there is a change in craniofacial pattern leading to the observed resolution of the Angle skeletal Class III malocclusion. This study thus provides strong support for the use of the orthopedic-force chin cup appliance in the clinical management of young patients with skeletal mandibular prognathism.
A review of the literature revealed that changes in the articular eminence associated with changes in the dentition were usually overlooked in most reports. An attempt was made to determine whether changes in attrition and loss of teeth would correlate with a change (decreased angulation) in the articular eminence. The population consisted of 103 adult skulls and mandibles of both sexes and three different races. They included partial and totol edentulism, mild to severe attrition, and complete dentitions in good condition. An impression of each of the 206 articular eminences was made and the angulation established. The data were transferred to computer cards and a statistical analysis performed. The level of significance for each of the variables was established and conclusions were made.
Five Macaca irus monkeys were used in this study to determine cephalometric and histologic changes after total maxillary impactions. In the three experimental animals, the maxilla was impacted 5 to 7 mm. and lateral cephalograms were taken over a 150-day period. By superimposing on craniofacial implants, osseous and dental changes were measured. Excellent skeletal stability was demonstrated during the postoperative period. Histologically, there was normal osseous healing of the osteotomized maxillas. Accompanying the counterclockwise rotation (overclosure) of the mandible, there was extensive change in the temporomandibular joint. In the experimental monkeys, the fibrous articular covering of the temporal fossa was thin and irregular. The condylar cartilage appeared atrophic and showed considerable aging; also, the articular disc was much thicker in the experimental animals. The study showed the superiorly repositioned total maxillary osteotomy to be a stable procedure after 150 days of postoperative observation. However, further studies are needed to investigate the neuromuscular and adaptive response of temporomandibular articulation and mandibular rest position after maxillary surgical procedures.
The position of the mandibular condyle in patients treated for mandibular protrusion by the oblique vertical osteotomy of the mandibular rami was studied on temporomandibular joint radiographs exposed according to the oblique transcranial projection. Forty-four adults participated in the study, and the radiographs were taken before the operation, 6 weeks postoperatively and 1 year postoperatively. At the 6-week postoperative control all the variables measured indicated a significant downward and forward displacement of the condylar fragment of about 1mm. The changes did not increase the variability of the joint morphology. At the 1-year postoperative control there were still significant differences in the position of the condyle compared with the pretreatment recording. A slight tendency to normalization was, however, observed. The mobility of the condyle, which was greatly restricted at the 6-week postoperative control, was fully restituted 1 year after the operation.
Many of the premises of dentistry that have evolved empirically have been re-evaluated in the light of newly-developed concepts of TMJ function. Centric relation, although duplicable, may not necessarily be correct. A "functional" centric relation exists when the TMJ radiographs can be correlated with the occlusal findings, in which case, the retruded classical centric relation should be used. When a "dysfunctional" centric relation is present (no correlation between the TMJ radiographs and occlusal findings), the most retruded position should not be used and a therapeutic centric occlusion should be created by the dentist. Subclinical TMJ dysfunction occurs more frequently than commonly thought, because TMJ radiographs are not routinely used. Retruded condylar displacements can be easily overlooked, because the lateral pterygoid muscle has relatively few stretch receptors compared to the elevator muscles of the mandible. Condylar retrusion, therefore, would not necessarily cause lateral pterygoid spasm as might be expected. The exact mechanism of the TMJ suspension system is unknown, although experimental evidence has shown that the condyle can be displaced superiorly with posterior unsupported muscle force. This indicates that the immutability of the condylar path under varying clinical conditions is questionable. Due to the superior displacement characteristics of the TMJ, the condyle does not act as the fulcrum in mandibular kinetics. The fulcrum, therefore, shifts to the teeth and/or bolus, depending on the specific situation. In either instance, whether considering bruxism or mastication, for most patients, an occlusion based on group function is preferable to a canine-protected occlusion to insure TMJ health. Scientifically, no one scheme of occlusion or articulation has been proven to be superior to any other scheme; therefore, the choice is a matter of the personal preference of the dentist.
The growth of the glenoid fossa is assumed to follow that of the cranial base. It has been observed recently that distal displacement in association with an obtuse cranial base angle is reduced on remodeling of the fossa anteriorly as a consequence of a more anterior position of the condyle in the fossa. The aim of this investigation was to simulate the increased distal displacement experimentally by causing a premature artificial cranial synostosis. Ten 10-day-old rabbits underwent gluing of the interparietal and temporoparietal sutures. These and ten controls were killed at 50 days for examination, and the articular surface of the right glenoid fossa was marked with a soft metal wire. The skulls were roentgenographed in standardized lateral projection. The articular surface was significantly shallower in relation to the skull base in the experimental group, and the glenoid fossa was located more superiorly and posteriorly. The most likely reason for the more horizontal direction of the articular surface is the more anterior location of the condyle, exerting increased pressure on the eminence. This becomes important, as it has recently been shown that in rabbits this shallowing of the fossa is associated with increased forward growth of the mandible.
The origin of the mandibular condylar cartilage is not periosteal, like that of the other secondary cartilages; this cartilage originates in a cellular blastema of its own. Despite the fact that the development of secondary cartilages, in general, is dependent on mechanical irritation, that of the condylar cartilage is not. The low level of function experienced postnatally seems to favor growth, but because the proliferation cells of the condylar cartilage are multipotential, they switch their differentiation pathway in the direction of osteoblasts in the absence of function, and growth of the cartilage ceases. This regulation of differentiation is mediated by maturation of the cartilage cells. If function is not present, maturation advances rapidly, and the mature cartilage induces bone formation instead of cartilage. Cyclic AMP and Ca are important mediators in this process, because they affect the advancement of maturation.
Ten orthodontic patients in whom a headgear-activator appliance was used in the first phase of treatment for Class II malocclusion were clinically evaluated. All patients had abnormal perioral muscle function at the initial examination. Myofunctional methods were used before and during active treatment. Pretreatment and posttreatment cephalometric tracings were evaluated to examine the effect of the appliance on dental, skeletal, and soft tissue structures. Five of the 10 cases illustrated distal movement of the lower first molar, a phenomenon not mentioned previously in the literature. Growth stimulation of the mandible was also observed in this patient sample, with some subjects demonstrating above-average mandibular growth when compared with a control group of normal subjects. Abnormal oral function was eliminated, and all patients had clinically acceptable results at the end of the treatment period. The headgear-activator appliance can be considered an effective tool for the control of vertical growth problems in growing mixed-dentition patients.
In a brief summary of the essential points aimed at, it may be stated: 1.1. That according to prevailing notions among orthodontists a face is normal when its dentition is in normal occlusion and, conversely, a face is abnormal when its dentition is in malocclusion. The inference is that orthodontic treatment changes the abnormal face to the normal as the dentition is restored to normal occlusion from malocclusion.2.2. That what is meant by a normal face is usually just taken for granted because it was at no time clearly defined.3.3. That a systematic metrical study of facial features of sixty-two young adult white males with full complements of teeth in normal occlusion reveals the fact that their faces are extremely variable.4.4. That in order to understand the nature of facial variation, it is essential to have a standard measure to determine what is normal and what is not normal.5.5. That by the use of the standard described, it is found that the dimensions of the facial features studied in the group with normal occlusion are not all normal. The proportion of those features which are normal to those which are not normal is on the whole approximately 2:1. In faces with dentitions in Class II Division 1 and Class III, it is extremely variable, ranging from 4:1 to 1:2.6.6. That dimensions of facial features which are not normal are found to be of two sorts. One comprises those dimensions which are larger and the other those which are smaller than normal.7.7. That in some facial features, the number of anormal dimensions which are larger is equal to those which are smaller than normal; that is, they are symmetrically divided.8.8. That equally or symmetrically divided dimensions have little significance beyond the fact that they are larger or smaller than the normal and that they are as likely to be the one as the other.9.9. That when unequally or asymmetrically divided, the dimensions of those features which are not normal indicate certain trends; that is, they are more often either larger or smaller than the normal.10.10. That asymmetrical division is to be noted both in dimensions of faces with dentitions in normal occlusion and in faces with dentitions in Class II Division 1 and Class III malocclusion.11.11. That in faces with dentitions in normal occlusion, the asymmetries are very slight while in those with malocclusion they are very marked.12.12. That as the asymmetries become more unbalanced, they clearly indicate (a) the differences between the same features in faces with dentition in normal occlusion and malocclusion and (b) the differences between features of faces with dentitions in Class II Division 1 and Class III malocclusion.It is thus clear that the use of the described “standard” provides a measure which greatly reduces the confusing intricacies of facial variation and simplifies the practical problem of appraising faces for orthodontic needs.
Practical Orthodontia
- Kronfeld
Temporomandibular Articulation
- Riesner
A Study of Bone and Tooth Changes Incident to Experimental Tooth Movement and Its Application to Orthodontic Practice
- Marshall
Histologic Analysis of the Jaws of a Child With Malocclusion
- Kronfeld
The Use of Bite Plates
- Callaway
Zur Frage der Orthodontisch Verursachten Wurzelresorption
- Gubler
Mechanics of the Mandible
- Stein
Die Wirkung der sogenannten Gaumenplatte
- Breitner
Textbook of Dental Histology
- Kronfeld
Ein weiterer Beitrag zur Frage der Bewegung belasteter Zahn
- Schwarz
The Temporomandibular Joint and the Occlusal Curve as Factors in Determining Tooth Position
- McLean
Mechanics in Orthodontia From a Modern Aspect
- Hellman