Tuesday, October 9, 2012
Orthodontic springs
Comment on this discussion topic
1. Classify the tooth movement
2. Specify the magnitude of the force, the direction and point of application
3. Also provide an illustration with each movement. (scan in hand drawing or post photo of hand drawing)
Ruweda Dawids Materials 1
Functional forces appear against the tooth only during normal oral function. Thus, each time the patient swallows, the activator directs the forces of the muscle contractions against the teeth. Functional forces are not easy to control and do not move the teeth as rapidly as dissipating or intermittent forces. it should be remembered, however, that loose removable appliances are not designed primarily as tooth-moving appliances but rather as devices to affect the growing craniofacial skeleton.
Ruan Louw - Materials
It is possible to rotate a body without translation by two moments that are equal, paralle, in the opposite direction and noncollinear-an arrangement of forces called a couple. A couple always induces a pure
rotational tendency. A force applied at different points on the body will produce different movements, but it does not make any difference where a couple is applied. A momnet is one force producing a sliding
vector. A couple is two forces equal, parallel, opposite and noncollinear in producing a free vector.
Ruan Louw - Theory
Describe in detail the opposing view which claims that mandibular reposturing produces an orthopaedic effect.
Damien Storey - Materials
1. Active Components (Anchorage)
Screws
– Uni-dimensional screws
– Bi-dimensional screws
Wire springs
– Finger spring
– Z-spring
– Canine retractor
– Short labial arch.
Screws
– Expansion is 1 mm. per one full turn i.e. 0.25 mm. per quarter turn
– May be used for moving one tooth or group of teeth (usually more
than one tooth to be moved with a screw)
– Have different sizes and range of activation
– Useful only when a few millimeters of space is needed
– Usually jackscrews been used as active component
– Clasps for retention
Expansion screws
– For anterior Expn. of Max. incisors
– For simultaneous Expn. of maxillary
incisors anteriorly and posteriors laterally
(Y-plate).
– Y-plate can be modified for Tx. Of
unilateral x-bite
– Maxillary split plate (By post. teeth tipping
not by opening mid-palatal suture).
Active plate
• The simplest uses of an active plate is to correct a maxillary anterior crossbite.
• Posterior biteplane is necessary in adult to allow clearance for the upper incisor to move out of crossbite (½ crown or more is covered).
Active plate split in midline will expand constricted maxillary arch almost totally by tipping the posterior teeth buccally Not by opening mid-palatal suture. Therefore this appliance is not indicated for skeletal crossbites or dental expansion for more than 2 mm per side.
1. Springs
– Provide extra length of wire to increase range of action and resiliency
– Extra length can be provided in the form of coil (s), loop (s) or change configuration to provide extra length
of the wire
2. Retentive Components
– Adam’s clasp
– C-clasp (Circumferential clasp)
– Lingual extension clasp
– Ball clasp
3. Acrylic Base Plate
It is used as a vehicle to carry all
Removable Appliance components together.
• It is the Anchor tool for tooth movement.
• Use self-curing acrylic resin.
Damien Storey - Theory 1
Explain his hypothesis (claims) that a Class II Div. I can be gradually changed to a Class I relationship by an appliance that makes the patient bite with the lower jaw in a normal relationship to the upper jaw.
plastic covering the palate and the teeth of both arches, designed to advance the mandible several millimeters
for Class II correction and open the bite 3 to 4 mm. The original design had facets incorporated into the body of the appliance to direct erupting posterior teeth mesially or distally, so, despite the simple design, dental relationships in all 3 planes of space could be changed.5
In designing an inert appliance that fitted loosely in the mouth and, because of its mobility, transferred
muscular stimuli to the teeth, jaws, and supporting structures, Andresen had taken a decisive step in
orthodontic treatment. Although he had effectively redesigned Robin’s monobloc to correct Class II Division
1 malocclusions, he declared that he had no knowledge of Robin’s work at the time.
Andresen’s novel device was not initially well received. First, removable appliances were not much accepted at that time. Second, the profession was under the influence of Martin Schwarz, whose active plate was then a common form of removable—not functional— appliance. Finally, Andresen advocated extractions, although not necessarily in connection with activator treatment. And, in contrast to Angle’s concept of ideal occlusion that was then prevalent, Andresen advocated a more realistic “individual and functional gnathological optimum.” Thus he was subjected to the same type of ridicule that Tweed endured years later.2
In 1925, Andresen, then director of the orthodontic department at the University of Oslo, began developing
for the government a simple method of treating Norwegian children. He modified his retainer into an
orthodontic appliance, using a wax bite to register the mandible in an advanced position.
Damien Storey - Materials
2. elastic working range,
3. ease of manipulation by permanent deformation to desired shapes,
4. capability of joining individual segments to fabricate more complex
appliances,
5. corrosion resistance and biocompatibility in the oral environment,
6. Cost: The beta-titanium and nickel-titanium archwires are much more
expensive than the traditional stainless steel alloys, but they offer
unique properties that should be carefully considered when selecting
wires.
Ruan Louw - Theory 2
BTech - block exams 2012
Please remember to post your information and check for updates.
Mouton, Theory 2
2.1. The Reverse Bionator:
The Reverse Bionator is used to treat the problem when the lower jaw is too big or the upper jaw is too small, possibly meaning that the lower front teeth are positioned in front of the upper front teeth. The Bionator try to adjust these growth patterns holding the lower jaw back while trying to accelerate the growth of the upper jaw. Again this appliance uses the bodies internal forces to redirect forces thus adjust growth.
2.2. The Open Bite Bionator:
When the upper front teeth and the lower front teeth do not meet as they should this is called the front open bite. Possible caused by the tongue coming between the teeth too often or perhaps a habit like biting on something, perhaps some sort of a comforter or pencil, it might also be caused by growth patterns meaning the upper jaw and lower jaw are growing at angles meaning the teeth are correct in the jaws but the jaw bones are too far apart. The Bionator attempts to adjust the position of the tongue, trying to hold the tongue away from between the front teeth. This has the effect of causing an area of "low pressure" in the front of the mouth the attempt at equilibrium often and hopefully has the effect of closing the bite.
Monday, October 8, 2012
Chuma Bezana - Theory 1
Discuss the contributing roles of Andresen and Kingsley in the origin and development of the functional appliances Viggo Andresen Designed an inert appliance that fitted loosely in the mouth and by its mobility transferred muscular stimuli to the jaws, teeth and supporting structures. This appliance was initially a Hawley appliance. The Hawley appliance teamed up with HAUPL, and it was called the Activator because of its ability to activate muscles. So Andresen designed the first appliance to transfer functioning stimuli to the jaws, teeth and supporting tissues.Norman KingsleyHistorians claim that two different men deserve the title of being called "The Father of Orthodontics." One man was Norman W. Kingsley, a dentist, writer, artist, and sculptor, who wrote his "Treatise on Oral Deformities" in 1880. What Kingsley wrote influenced the new dental science greatly. The history of the functional appliance can be traced back to 1879, when Norman Kingsley introduced the "bite-jumping" appliance. The earliest evidence of functional orthodontics was an appliance designed by Kingsley, this dentally anchored appliance was meant to maintain the mandible in a forward position. A Kingsley appliance is considered a prototype functional appliance due to its continuous labial bow and bite planes extending posteriorly. Kingsley is known as the “father” of functional appliances.
Chums Bezana - Theory #2
Provide a full description of the position, extension and angle of the inclined plane of the mandibular acrylic block with reference to treating or correcting a deep overbite condition.
Twin Blocks are simple bite-blocks that effectively modify the occlusal inclined plane using upper and lower bite blocks which engage on occlusal inclined planes.. Wearing bite-blocks is rather like wearing dentures and patients can eat comfortably with the appliances in place. The upper and lower bite blocks engaged mesial to the 1st permanent molar at 90° to the occlusal plane, when the mandible postured forward. This positioned the incisors edge-to-edge with 2 mm vertical separation to hold the incisors out of occlusion. The patient had to make a positive effort to posture the mandible forward to occlude the bite blocks inprotrusive bite.The inclined plane on the lower bite-block is angled from the mesial surface of the second pre-molar or second deciduous molar at 70° to the occlusal plane. This places the leading edge of the inclined plane on the upper appliance mesial to the lower first permanent molar, thus keeping a provision for the unhindered eruption of the lower 1st permanent molar. Mesially, the lower bite block extends up to the canine region with a flat occlusal surface.Twin Block appliance acrylic extends to cover the incisal edges of lower incisors. This helps to avoid tipping of the lower incisors and improve in retention. Torquing springs were used to control position of the upper incisors.
Chums Bezana - DMaterials
Explain, in short, why heat treatment is sometimes used in stress relieving stainless steel orthodontic wire.
Heat treatment is generally applied to orthodontic stainless steel wires to relieve the stresses that result from their manipulation by orthodontists. The quality and thickness of the oxide films formed on the surface of heat-treated wires can vary, and it is believed that these oxide films can influence the properties of heat-treated wires. It is also used to improve the wires elasticity, stability of the dislocations and the shape of the wire.
Pongolo Theory
Name three types of Bionator designs which are used to correct various malocclusions or oral conditions, and clearly explain the correction for which each type of appliance is used.
The three bionator designs are the basic bionator with a basic wire, a tongue screening bionator with palatal wire and a class III bionator in contract to the two previous types mentioned. The basic bionator is employed in Class I and Class II division cases. The tongue screening bionator is used in cases where there is an open bite or tongue dysfunctions are present. The Bionator Class III appliance is used for correcting Class III malocclusions. It can be used to modify or distract the mandible as well as open the bite, close the bite, or hold the vertical dimension constant.
Pongolo Theory
Give a concise explanation of the mechanism of bone remodeling in response to functional stimuli during mastication.
During mastication, forces are transmitted through the teeth to the alveolar bone and to the underlying basal bone. Most of these forces are vertical, but some are transverse and Anteroposterior. The external surface of the maxilla and mandible is modified precisely by function to absorb the forces of occlusion. Well-defined ridges of bone are specifically designed to absorb and transmit these force vectors.Mastication is a function that involves the whole face and even part of the cranium. Considerable forces are applied through the muscles of mastication to the teeth and underlying bony structure to influence both the internal and external structure of the basal bone. It is this natural mechanism of bony remodeling by occlusal force vectors that forms the basis of functional correction by the Twin Block technique. The forces of occlusion that are applied during mastication are harnessed as an additional stimulus to growth.
Siphon Pongolo DMaterials
Stainless steelThe main objective of a dental laboratory is to manufacture clinically acceptable devices for a profit. As a laboratory owner, it is essential to select the most affordable, yet convenient materials. Stainless steel is less expensive than nickel-titanium and since it is the most commonly used orthodontic wire, it would be most convenient for a laboratory to utilize. The main objective of orthodontic treatment is to obtain good aesthetics in the least amount of time. It has good formability, thus wires can be bent to required specifications. Stainless steel has been clinically proven to be biocompatible in the oral cavity therefore it will harm or cause infectious developments in the patient’s mouth. Stainless steel orthodontic wires can be soldered and weldered, unlike nickel-titanium which is essential when attaching auxiliaries or when fabricating certain removable appliances such as the space maintainer or a distally extended labial bow. Both nickel-titanium and stainless steel are resistant to corrosion, owing to the oxide film characteristic of their surface topography.
Sipho Pongolo Theory 1
Wolff’s law of the transformation of bone “forms the basis of functional correction of the Twin block technique.
The internal and external structure of bone is continuously modified throughout life by the process of bony remodeling. The sensory feedback mechanism helps the bony remodeling process to address the changing requirements of function in dentofacial development. Occlusal forces transmitted by the muscles of mastication through the teeth to the underlying bone provide a proprioceptive stimulus to influence the external form and internal trabecular structure of the supporting bone.Unlike the other connective tissue, bone responds to mild degrees of pressure and tension by changes of this nature. These changes are achieved by means of resorption of existing bone and deposition of new bone. This may take place on the surface of the bone, under the periosteum or, in the case of cancellous bone, on the surfaces of the trabeculae. In this respect, bone is more plastic and adaptive than any other connective tissue. The internal and external structure of bone is modified my functional requirements to enable it to withstand the physical demands made upon it with the greatest degree of economy of structure. The principle is exemplified in Wollf’s law of transformation of bone. The architecture of a bone is such thatit can best resist the forces that are brought to bear upon it with the use of as little tissue as possible.
M.K Mouton Theory 1
In the first phase of the activator construction, after the common clinical procedure, the construction bite in a eugnathic relationship is taken, with the mandible forced forward until the upper canine between the lower canine and the first lower premolar relationship is achieved. The construction bite is taken with the mandible protruded 4-6 mm and interocclusal space of 2
3 mm above physiological rest in the molar region. During the procedure of construction bite taking, great care should be exercised regarding the middles of the jaws. After this, the trial of the wax activator follows to check the relationship between the jaws and possible corrections
The activator appliance consistes of an acrylic intermaxillary block with upper labial arch (0.8 mm) which passively touches the incisal third of the upper incisors. The acrylic is then extended to cover the incisal third of the mandibular incisors in order to prevent the labial tipping of these teeth. The acrylic then extends to the lower lingual sulcus to provide stability and anchorage. At control visits, the acrylic will be trimmed behind the upper front teeth, which is in concordance with treatment of protruded incisors in the sense of their retrusion and overjet reduction. The interocclusal acrylic in the molar and premolar region is not trimmed until the improvement of the sagittal jaw relationship is achieved, in cases with associated deep bite. In the last phase, the acrylic is trimmed selectively according to the occlusal needs of the lateral teeth. Patients are advised to wear the appliance 15 hours a day.
Ruweda Dawids theory 2
Ruweda Dawids, Theory 1
The use of functional appliances offers a number of possibilities such as guiding skeletal growth and modifies the patient’s neuro-muscular behaviour. There are several functional appliances available and each of them has different functions. The different functional appliances and their functions:
• A Clark twin block appliance incorporates the use of upper and lower bite blocks to position the mandible forward for skeletal Class II correction.
• Headgear is an orthodontic appliance for the correction of Class II correction, typically used in growing patients to correct overbites by holding back the growth of the upper jaw, allowing the lower jaw to catch up. The headgear can also be used to make more space for teeth to come in. Headgear needs to be worn approximately 12 to 22 hours a day to be truly effective in correcting the overbite, and treatment is usually anywhere from 6 to 18 months in duration, depending on the severity of the overbite and how much a patient is growing.
• Orthodontic facemask and reverse-pull headgear The appliance is used in growing patients to correct under bites known as a Class III orthodontic problem by pulling forward and assisting the growth of the upper jaw, allowing the upper jaw to catch up.
• Herbst Appliance corrects overbites by holding the lower jaw in a protrusive position. This appliance is most commonly used in non-compliant patients. The Herbst appliance is very effective in correcting large overbites due to small lower jaws in patients that are growing.
• Fixed twin block removable appliance- high comfort level allows you to wear it 24 hours a day. This appliance actually is made up of two separate appliances that work together as one. The upper plate includes an optional expansion screw to widen your upper arch, if needed, as well as pads to cover your molars. The lower plate includes pads to cover your lower bicuspids. These two appliances interlock at an angle, and they move your lower jaw forward and lock it into the ideal position when you bite together. This new position, while temporary, will eventually become the permanent corrected position.
Sindile Gcelu, Material Science I
Explain why and also indicate the most desirable direction of force to be used with a functional appliance
Muir & Reed (1979) states that most multiband appliance systems make extensive use of extra oral forces. By comparison such forces are much less used with removable appliances. There is no good clinical reason why this should be so. Extra oral forces can readily be adapted for use in removable appliance orthodontics and can extend considerably the range of treatment which can be undertaken.
It is possible that heavy extra oral force applied for a substantial proportion of each day to a patient who is growing rapidly may have an orthopaedic effect. In addition to distal movement of teeth through bone there could be a restraint on maxillary growth. Headgear can be applied either directly to a removable appliance or indirectly to molar bands over which the appliance is clipped. Therefore, it is necessary to avoid patterns of headgear that delivers cervical traction (neck strap). It is recommended to use full headgear when applying force directly to a removable appliance.
Ref: Muir, J.D., Reed, R.T. 1979. Tooth Movement with Removable Appliances. USA: Pitman Medical. Pg 82.
Sindile Gcelu Theory 2
Without referring to any of the study material that deals with the historical and functional development of the Functional Appliance, give your own evaluation or opinion as to the effectiveness of these appliancesAccording to Graber & Neumann (1997) indicates that, the maximum power of the muscle activity is not as important as the orderly coordination of the manifold functions. Malocclusion thus must be regarded as a disturbance of that coordination, there may be a cause of the in coordinate activity. Of no minor importance may be the psychological component, producing Para functional influences by which the action of the finger, tongue, lips, cheeks, etc. will produce deformation.
Sindile Gcelu, Theory I
According to Balters’ philosophy, Class II malocclusions are a consequence of a backward position of the tongue, disturbing the cervical region. The respiratory function is impeded in the region of the larynx and there is thus a faulty deglutition. Alongside, there is mouth breathing.
Effectiveness of Bionator appliance:
• To accomplish lip closure and bring the back of the tongue into contact with the soft palate.
• To enlarge the oral space and to train its function.
• To bring the incisors into an edge-to-edge incision or relationship.
• To achieve an elongation of the mandible, which in turn will enlarge the oral space and make the improved tongue position possible?
• An improved relationship of the jaws, tongue, and dentition, as well as the surrounding soft tissue will result.
Cheryl Wolfe Theory 2
In order for normal development of the dental arches in the correct relationship to occur, favourable equilibrium of muscle forces between the tongue, lip and cheeks are essential. Malocclusion is therefore a result of persistant deviation from normal function. The purpose of functional therapy is therefore to change the functional environment of the dentition to promote normal function. The purpose of a functional appliance is to control the forces applied to the dentition by the surrounding soft tissues as well as the muscles that control the position and movement of the mandible. A new functional behaviour pattern is therefore established in order to support a new position of equilibrium by eliminating unfavourable environmental factors in a developing malocclusion. Functional thereapy also aims to unlock a malocclusion and stimulate growth by applying favourable forces that enhance skeletal development.
Clark, W.J. 1995. Twin Block Functional Therapy: Applications in Dentofacial Orthopaedics. London: Mosby-Wolfe. p31-32