Evolution of Functional Appliances
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY Leader in continuing dental education
www.indiandentalacademy.com
www.indiandentalacademy.com
• Correction of malocclusion, primarily by means of controlled movement of the developing and mature dentition into a desirable occlusal relationship • Control and modification of growth of skeletal structures of the craniofacial complex, especially via tooth borne appliances
www.indiandentalacademy.com
Various views on biology of tooth movement • Bone resorption on one side and deposition on the other side of the root
Harris (1863) Talbot (1888) Guilford (1898)
• Concept of alveolar bone Kingsley (1877) bending during Farrar (1888) orthodontic tooth movement
www.indiandentalacademy.com
• Oppenheim (disciple of E.H.Angle) based on Walkoff’s pressure theory introduced the concept of overcoming the tension of the bone by strong pressure for a very short time + prolonged retention. • His findings proved a scientific foundation for angle’s empirically developed methods of treatment and from then on, orthodontic treatment was regarded as artificially affected resorption and deposition of bone. www.indiandentalacademy.com
• Ketham – Emphasised the practical importance of tissue reaction to orthodontic treatment. • In America , -Heavy rigid appliances, apparently responsible for root resorption, were abandoned in favour of Angle’s edgewise appliance. -
www.indiandentalacademy.com
• In Europe, The “ Biological superiority ” of removable appliances was reinforced due to the pioneering work of -- Anderson -- Schwarz -- Haupl - Supported by definitive research.
www.indiandentalacademy.com
Various authors involved with evolution of functional appliances
www.indiandentalacademy.com
•
Schwarz recognised the intimate relationship b/w force magnitude and tissue response and classified orthodontic forces into 4 types of biologic efficiency.
1. Forces below the threshold of stimulation to activate orthodontic tooth movement. Balanced by compensatory forces. 2. The most favourable to achieve continuous tooth movement without root resorption. i.e. weaker than the forces exerted by blood pressure (15-20 gms/sq.cm) www.indiandentalacademy.com
3. Forces interrupt blood circulation in Pdl. ( 20-50 gms/sq.cm ) - Tissues not yet crushed and will recover if circulation is restored. - i.e. the repeated application of these type of forces, interrupted in time are conductive to resorption and deposition of alveolar bone. 4. Forces are of the highest magnitude that the pdl is crushed b/w the root and the alveolar bone. ( >50 gm/sq.cm) - If continous, the consequence is extensive necrosis of the alveolar bone and root resorption, which is irreparable. www.indiandentalacademy.com
• Reitan objected the above gradation of forces and stated that no such gradations were observed in histological sections. • According to him the effect of forces is more related to the surrounding anatomical environment and time factor. • However, the historical importance of Schwarz's gradation of forces called attention to the damaging effects of excessive force, such as those of the third and fourth degree. www.indiandentalacademy.com
• Haupl was another famous personality who believed in the European “jaw orthopedic thinking” • His treatment was based on: Roux theory on bone formation • Importance to trophic stimuli • These trophic stimuli would “shake the bone substance” and increase the cell activity of the osteoblasts leading to the deposition of bone. www.indiandentalacademy.com
• Haupl claimed that the activator would provide such stimuli, leading to primary bone formation on the pressure side, and that the newly formed bone would move the teeth. • Supported by Haupl and Eschler’s experiment on dogs.
www.indiandentalacademy.com
• Haupl’s theory of tissue reaction : - Mild pressure narrowed the pdl space - Tissue made sensitive to functional stimuli providing the essential “shaking of the bone molecules” leading to bone deposition and resorption. - The most favourable way to achieve this is by the use of passive appliances which do not narrow the pdl space permanently. www.indiandentalacademy.com
• His teachings had an enormous impact on orthodontics in many parts of europe and his followers limited themselves to the exclusive use of the activator. • Fixed appliances were rejected in europe due to: - Concern over increased root resorption. - Economic reasons : British health service plan. - Outstanding clinicians succeeded in extending the possibilities of removable appliances. - Lack of knowledge of fixed appliances. www.indiandentalacademy.com
• Soon after the invention of vulcanite it was used for “Regulating devices” • At the time of world war II there were two distinctly different devices which were in use 1. Active plate : utilised the forces within the appliance. 2. Activator : utilised muscular forces.
www.indiandentalacademy.com
• Norman W. Kingsley (1879) Described his plate for “Jumping the bite” • Pioneer in orthodontic therapy to use the forward positioning of the mandible. • “It was adapted to the inside of the superior dental arch and the inclined surface projected below and caught the lower incisors”
www.indiandentalacademy.com
• The treatment was to expand both the upper and lower arches and reduce the protrusion of the maxillary teeth. • Then the mandible was moved forward by muscular action to attain proper M-D position. • The main objective was not to protrude the lower teeth, but to change or jump the bite in the case of an excessively retreating lower jaw. www.indiandentalacademy.com
• Further clinical trails by Kingsley and others demonstrated the difficulty of holding the forward position of the lower jaw and therefore was seldom used except some of its modifications: • • • •
Vorbissplate (Hotz) Hawley’s Biteplate Ottolengui’s modification Herbert A.Pullen, J.Lowe Young, Oren Oliver -- Combined with fixed appliances. www.indiandentalacademy.com
• Nowadays the term “Jumping the biteâ€? is widely used for the forward positioning of the mandible with functional appliances the main difference being -- dislocating the mandible to stimulate alveolar or condylar changes, or both, to achieve the desired occlusion by stages.
www.indiandentalacademy.com
Monobloc (Pierre Robin-1902) • Passive positioning device • Modified from bite jumping vulcanite maxillary guide planes designed by Norman Kingsley (1880) • Indicated in patients with glossoptosis and severe mandibular retrognathism who risked occluding their airways with their tongue. www.indiandentalacademy.com
• Robin noted that forward mandibular posture reduced this hazard and significantly improved the jaw relationship. • This problem usually associated with cleft-palate patients, became known as the Pierre robin syndrome. • Was quite similar to Anderson's activator but lacked publicity. www.indiandentalacademy.com
The original Activator (Viggo Anderson-1908) •
Influenced by 1. Kingsley’s concept of “Jumping the bite” and modified his plate – ‘working retainer’ 2. Theories of Roux and Wolff (late 1890’s) “changes in function bring with them changes in internal bone structure and external bone form”
www.indiandentalacademy.com
3. Lischer’s theory: If abnormal musculature can exacerbate existing malocclusions, can not the same muscles be used to correct these problems?
www.indiandentalacademy.com
www.indiandentalacademy.com
Anderson’s original hypothesis • He claimed that a class II relation can gradually be changed into a class I relation by an appliance that makes the patient bite with the lower jaw in a normal relation to the upper. • Increased activity – protractors, elevators • Relaxation and stretching of the retractors.
www.indiandentalacademy.com
www.indiandentalacademy.com
• Dysfunctions will be eliminated, and an adjustment of the complete orofacial muscle complex to the new functional pattern will be induced with adjustments in the bony structures. • The teeth will be moved by intermittent forces generated in the muscles and transmitted through the appliance.
www.indiandentalacademy.com
• i.e. the tooth moving forces are brought into being by kinetic energy provided by the stretching of muscles. • Gradually the whole chewing apparatus will adapt to the jaw relationship prescribed by the appliance. • Musculoskeletal adaptation by inducing a new pattern of mandibular closure • Condylar adaptation: growth in upward and backward direction to maintain integrity of TMJ structures www.indiandentalacademy.com
www.indiandentalacademy.com
• Initially not accepted in US: - facial growth could not be affected - tooth position can be altered with appropriate appliances and biomechanics • Later modified and used by Harvold and Woodside.
www.indiandentalacademy.com
Requisites 1. The appliance itself should be passive. 2. It should force the mandible to assume a new closing pattern, bringing it into the desired relationship to the upper jaw. 3. It should be loose in the mouth in order to provoke the orofacial muscles to bite it into place. 4. Recommended to be used in the night . www.indiandentalacademy.com
• He originally termed his appliance Biomechanical orthodontics Functional jaw orthopedics • Anderson then moved from Denmark to Norway and worked at the University of Oslo where he associated with Haupl.
www.indiandentalacademy.com
• Haupl : -- Eminent periodontist, Histologist. -- advocated the work of Roux ‘shaking the bone’ -- He was convinced that Anderson’s appliance induced growth changes in a physiologic manner. • Started working with Anderson and they together coined the term “Activator” because of its ability to activate the muscle forces. www.indiandentalacademy.com
• Types of force employed in activator therapy: - Sagittal: mandible downward and forwardmuscle force to condyle and slight reciprocal force to maxilla - Vertical: teeth and alveolar processes are either loaded or relieved of normal forces ; high construction bite inhibits growth, direction and inclination of maxillary base - Transverse: incorporation of screws and springs; midline correction www.indiandentalacademy.com
• As to whether the activator promotes mandibular growth, they defined the term “Individual optimum” • According to them : -- The activator cannot create a large mandible from a small one, but it can help the patient achieve the optimal size consistent with morphogenetic pattern. -- Haupl considered this as their goal of treatment. www.indiandentalacademy.com
• Various authors had different views as: -- Growth prediction, direction and timing were not properly defined at that time and were all vague concepts. -- Also the reciprocal effect on maxilla was essentially ignored for most of the history. -- Their hypothesis was objected by several authors.
www.indiandentalacademy.com
• First to reject Anderson's hypothesis was Selmer-Olsen. He stated that “Muscles cannot be stimulated to action at night because nature has designed them to rest during sleep” • His interpretation was based on the assumption that the mandible is displaced beyond rest position by the appliance
www.indiandentalacademy.com
• The disagreements b/w Anderson and Selmer Olsen reflect current divergences in the analysis of muscle response to the activator in general to the functional appliances. • His views were later supported by the findings of : Thompson (1946) : Ahlgren (1960) : Woodside (1973) www.indiandentalacademy.com
• Herren (1953) -- On the basis of the spatial relationship b/w mandible and postural rest position he came to the opposite conclusion. -- According to him the equilibrium b/w various forces was the most important. - Gravity - Air pressure - Muscle tonus - Muscle tension www.indiandentalacademy.com
• Changes of head posture alter the magnitude and direction of force • Change in mandibular position varies force vectors acting on mandible and different muscle groups • Plane of sleep( light or deep), intraoral air pressure, dream cycle, state of mind also affect activator response during sleep.
www.indiandentalacademy.com
www.indiandentalacademy.com
• Woodside “ Tooth moving forces in activator are brought into being by streching of the soft tissues – viscoelastic properties” • i.e. use of potential energy
www.indiandentalacademy.com
• Grude (1952) - Anderson’s associate. - Reviewed some of the cases after their treatment by Activator. - He concluded that the appliance works in the way described, provided the mandible is not displaced beyond the rest position.
www.indiandentalacademy.com
Original appliance • The original appliance had a basic vulcanite or acrylic fabrication consisting of joined maxillary and mandibular components. • Only one wire element was used, a labial arch for the upper anterior teeth. • To achieve expansion the appliance was split in the center and a flexible coffin spring was incorporated. www.indiandentalacademy.com
Construction bite • Purpose : - To bring the lower jaw into a tolerable forward positioning. - To “ Block the bite ” i.e. to prevent the eruption of ant. teeth while attempting to stimulate the eruption of posterior teeth.
www.indiandentalacademy.com
• The optimal forward movement of the mandible for the construction bite is usually half the individuals normal range ( 7-10 mm) • Opening of the construction bite 2mm in excess of the individual’s postural resting position. i.e. 4-5 mm-molar region, 6-7 mm in incisor region • Based on functional analysis only mild skeletal and not dental midline shifts should be corrected.
www.indiandentalacademy.com
Modifications of Activator • Some appliances consist of one rigid acrylic mass but with reduced volume or bulk referred to as open activators. • Their goal is to restore exteroceptive contact between the tongue and the palate which is prevented by the classical activator. - Elastic open activator : Klamant (1955)
www.indiandentalacademy.com
• Some appliances consist of 2 parts joined with wire bows. The flexibility or elasticity of the appliance permits mandibular movements in all directions • Ex: Schwarz double plate Stockfish’s kinetor
www.indiandentalacademy.com
www.indiandentalacademy.com
• For sophisticated use various springs and jackscrews were added later. • Eschler (1952) developed modifications of the labial bow that improved intermaxillary effectiveness. - One part was active, moving the teeth. - The other was passive, holding the soft tissue of the lower lip away and thus enhancing the tooth movement desired.
www.indiandentalacademy.com
• In co-operation with Petrix(1957) they explained the use of additional wire elements. • Stockfish recommends round and rectangular wires (fixed appliance therapy) which could be used to complete treatment, on account of the inherent limitations of removable appliances.
www.indiandentalacademy.com
www.indiandentalacademy.com
Herren and LSU Activator (1953) • His method is in complete opposition to the kinetic concept • Construction bite taken in a strong mandibular propulsion. • Activator fixed by clasps to the maxillary dentition.
www.indiandentalacademy.com
• Bite opened well beyond postural rest position • Forward positioning of mandible leads to reduced increase in length of LPM • Sensory engram formed for new position of mandible • Functioning of mandible in more forward position when appliance is not worn • Increased activity of retrodiscal pad with acceleration of condylar growth www.indiandentalacademy.com
• Growth restriction of glenoid fossa: -Normal growth of glenoid fossa is in posterior and inferior direction -Anterior slope of articular eminence undergoes bone deposition on posterior slope and resorption on anterior slope -Anterior relocation of glenoid fossa in orthopedic treatment -Reciprocal forces from viscoelastic tissue between condyle and fossa www.indiandentalacademy.com
www.indiandentalacademy.com
Wunderer modification for Cl III M.O • Appliance split horizontally ,with the upper and lower portions connected by a screw that is embedded in an acrylic extension of the mandibular portion behind the maxillary incisors. • As the screw is opened the maxillary portion moves anteriorly with a reciprocal posterior thrust on the mandibular dentition. www.indiandentalacademy.com
www.indiandentalacademy.com
Bow activator of A.M.Schwarz(1956) • The upper and lower halves are connected with an elastic bow which enables the correction of Cl II by periodic adjustment of the bow.
www.indiandentalacademy.com
www.indiandentalacademy.com
Karwetzky modification(1964) • Consists of maxillary and mandibular active plates joined by a U-bow in the region of the first permanent molars. • Extends over the occlusal aspects of all the teeth • Construction bite is taken with the mandible in the postural resting position. • Depending on where the ends of the U-bow are placed, 3 types of Karwetzky activator are created. www.indiandentalacademy.com
• U-bow : 1 long leg ; 1 short leg • By constricting the bow, i.e. narrowing the U-bend mandibular horizontal movements are created. www.indiandentalacademy.com
www.indiandentalacademy.com
Reduced activator of Schmuth(1973) • Acrylic portion of the appliance is reduced • Labial wire will not be damaged as with the original appliance. • A coffin spring in the palatal portion and the lower acrylic portion is divided to permit expansion. • Can be simultaneously used along with fixed appliances. www.indiandentalacademy.com
www.indiandentalacademy.com
• Muzy (Rome) considers the action of the activator as achieved by muscular-functionalbiomechanical forces. “ One source of energy derives from excessive
muscular function as the result of continuous jaw closure. The second mechanical source of energy is the system of inclined activator planes.”
• According to him the vertical and horizontal pressures were inhibited due to the large size of the activator and therefore reduced the size considerably and joined the side elements with a curved elastic sliding splint. www.indiandentalacademy.com
www.indiandentalacademy.com
Harvold-Woodside Activator • Maximal mandibular protrusion minus 3mm • Vertical bite 8-10mm > than inter-occlusal space i.e. average of 12-15mm • According to Harvold his “ Functional occlusal plane ” is the result of neuromuscular forces, growth and functional adaptation during development of dentition arresting the growth of the maxillary posterior teeth. www.indiandentalacademy.com
• At the same time, the posterior mandibular teeth should erupt vertically together with vertical growth of the lower half of the face. • As lower molars erupt at right angles to the plane, disto-occlusion is converted to neutroocclusion. • Hence the high vertical working bite. www.indiandentalacademy.com
www.indiandentalacademy.com
Open activator of Klammt • Not only supported by the mandible but also stabilized by the action of the tongue and uses the formative forces of the tongue. • Indicated in cases of narrow maxilla with distal bite and anterior crowding where 3-dimensional arch development is required. • Vertical pressure together with additional tongue pressure in a sagittal direction leads to an increase in dental arch length. www.indiandentalacademy.com
www.indiandentalacademy.com
窶｢ C.F.L.Nord (1929) At the meeting of the European orthodontic society in Heidelberg presented very simple screw split plates meant for the treatment of the masses. 窶｢ M.Tishler (1936) 9th International dental congress 窶天ienna demonstrated quite sophisticated active plates. www.indiandentalacademy.com
• A.M.Schwarz (1938) - Published a textbook entirely devoted to treatment with plates. • Basic components of Active plate : 1.Baseplate 2.Clasps 3.Active elements
-- In addition to these use of extraoral traction gained much importance. www.indiandentalacademy.com
1. Baseplate : -
As a base of operations to carry all working parts. To serve as anchorage. To be an active part of the appliance itself as indicated by the specific orthodontic problem. Used in the treatment of TMJ Dysfunction, Pdl disease, Bruxism, excessive overbite.
2. Clasps : - To secure the baseplate. -
Arrow clasp (A.M.Schwarz), Triangular clasp, delta clasp, Adams clasp. www.indiandentalacademy.com
2. Clasps : - To secure the baseplate. -
Arrow clasp (A.M.Schwarz), Triangular clasp, delta clasp, Adams clasp.
3. Active elements: -
Labial wire Springs Screws Elastics
www.indiandentalacademy.com
www.indiandentalacademy.com
• The operator will select a combination of all these elements to construct the device for the particular treatment. • Choice is made according to the requirements of the case at hand, the mechanical possibilities offered by the different parts and the preference of the orthodontist.
www.indiandentalacademy.com
www.indiandentalacademy.com
• Schwarz double plate : - Attempted to combine the advantages of the activator and the active plate. - The maxillary appliance was modified by extending flanges into the lower dental arch. - 1st to achieve simultaneous expansion along with correction of CL 2 div1. - Other similar designs were developed by Pedro planas (Madrid) Charles nord (Amsterdam) www.indiandentalacademy.com
www.indiandentalacademy.com
Bionator • Balters (1943) • Equilibrium between tongue and circumoral muscles influences shape of dental arches and intercuspation • Tongue is the center of reflex activity in the oral cavity
www.indiandentalacademy.com
www.indiandentalacademy.com
• Position of the tongue: class II : Posterior displacement class III : low anterior displacement : Narrow arches and crowding : low outward pressure Open bite : hyperactivity and forward posture
www.indiandentalacademy.com
• Forward posturing of mandible: - enlargement of oral space - dorsum of tongue contacting soft palate - accomplish lip closure
www.indiandentalacademy.com
Effects: • Modulation of muscle activity of tongue • Elimination of abnormal influences of perioral musculature • Stimulation of myotactic muscle activity and isotonic muscle contractions • No vertical component except for guiding eruption of teeth • No viscoelastic response • Prevention of deleterious parafunctional activity at night : relaxation of lateral pterygoid ( used for TMJ problems) www.indiandentalacademy.com
Thank you www.indiandentalacademy.com Leader in continuing dental education
www.indiandentalacademy.com