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Orthodontic
Vet Dentistry
Question | Answer |
---|---|
What is ORTHODONTICS? | The area of dentistry concerned with the supervision and guidance of the growing dentition and correction of the mature dentofacial structures |
What are potential sequellae of malocclusions? | 1. problems with mastication 2. TMJ dysfunction 3. caries formation 4. periodontal disease 5. dentofacial growth/developmental abnormalities 6. soft tissue trauma 7. traumatic dental fractures 8. dental attrition |
What is the basic goal of orthodontic therapy? | Harmonious occlusion (not cosmetic orientation of teeth) |
What is DENTOFACIAL DEFORMITY? | Abnormalities of the teeth in morphology or location and/or of the facial support structures |
What are the 3 general categorical causes of dentofacial deformities? | 1. heredity 2. systemic influences: prenatal vs postnatal 3. local influences |
What are examples of systemic influences? | 1. nutritional disturbances 2. infectious diseases 3. endocrine imbalances 4. radiational effects 5. chemical instigations |
What are examples of local effects? | 1. trauma 2. periodontal dz 3. cysts 4. tumors 5. behavior/habits (inappropriate chewing, sucking, etc) |
What is Class O occlusion? | Normal, orthoclusion |
What is Class 1 malocclusion? | Neutroclusion (normal mesio-distal relationship w/faciolingual variations) |
What is Class II malocclusion? | distocclusion |
What is Class III malocclusion? | mesiocclusion |
What is the definition of OCCLUSION? | the contact of the teeth of the maxillary arch with those of the mandibular arch |
What is CENTRIC occlusion? | The position of the arches in relation to each other when the teeth are in maximum occlusal contact |
What is STATIC occlusion? | the relationship of the teeth when the jaws are closed in centric occlusion |
what is CENTRIC RELATION? | The most functional, unrestrained, anatomically retruded positionof the heads of the condyles of the mandible in the glenoid fossae of the TMJ |
What is a SCISSORS bite? | the maxillary incisors overlap the mandibular incisors whose incisal edges rest on or near the cingulum on the lingual surfaces of the maxillary incisors |
What is TRANSPOSITION? | condition where 2 teeth have exchanged places during the development of the occlusion |
What is EMBRICATION? | irregularly arranged teeth within an arch due to lack of space (crowding) |
What is INFRACLUSION? | describes teeth in which the occlusal surface or incisal edge has not reached the same or appropriate level of other teeth of the same type |
what is SUPRACLUSION? | Describes teeth that are above their appropriate occlusal level |
What is SUPERERUPTION? | teeth whose cementoenamel junction erupted above the normal level |
What is TORSIVERSION? | rotated or turned teeth |
What is MESIOLINGUAL rotation? | tooth rotated on its long axis so the mesial aspect is moved toward the tongue |
What is DISTOLINGUAL rotation? | tooth rotated on its long axis so the distal aspect is moved toward the tongue |
What is MESIOVERSION? | A tooth whose crown leans in a mesial direction (more correct than 'rostroversion') |
What is DISTOVERSION? | when a tooth's crown leans in a distal direction |
What is LINGUOVERSION? | When a tooth's crown leans in a lingual direction |
What is FACIOVERSION? | tooth's crown is leaning away from the tongue |
What is RETROCLINATION? | lingual tilting of the anterior teeth |
What is LABIOVERSION? | sometimes used to describe facioversion of the anterior teeth |
What is BUCCOVERSION? | Sometimes used to describe facioversion of the posterior teeth |
What is DISPLACEMENT? | describes a tooth in which both the crown and root have moved principally in the same direction |
What terms are used to describe displacements in different directions of a tooth or group of teeth? | 1. mesioclusion 2. distoclusion 3. linguoclusion 4. facioclusion, labioclusion, buccoclusion |
What does VERSION mean? | describes inclination or tilting in directions of teeth that are generally in their correct position in the dental arch |
What does orthodontic intervention aim to provide? | reasonably functional, esthetic, stable, and harmonious occlusion |
What are the 4 goals to strive for in orthodontic intervention? | 1. proper assessment & supervision of occlusion 2. removal of etiologic factors (interceptive) 3. correction of conditions that may allow occlusion to deteriorate (prevention) 4. establish and maintain as functional and close to normal occlusion as pos |
What are the 3 general categories of orthodontic treatment? | 1. interceptive 2. preventive 3. corrective |
What is INTERCEPTIVE orthodontics? | extracting or recontouring (crown reduction) of primary or secondary teeth |
What are the 3 components of Preventive orthodontics? | 1. occlusal assessment and supervision 2. spacial control 3. behavioral control |
What are the 2 stages of corrective orthodontics | 1. active treatment 2. retention |
At what age should orthodontic treatment be instituted? | As young as possible: young growing bone is more receptive and responsive to changes than older, mature/static bone |
What are disadvantages of implementing orthodontic therapy at too young of an age? | may require prolonged supervision for retention or retreatment due to recoil or drift |
What is Wolff's Law of transformation of bone? | states that the structural form of bone will be that which is best suited to withstand the forces placed on it,and the quantity of bone tissue will be the minimum needed for its functional requirements |
What dictates cellular response in orthodontic movement? | degree and duration of applied force: changes in capilllary pressures stimulate cellular changes in adjacent tissues |
What is the average intracapillary pressure in humans? | 20-30 mm Hg |
What is PHYSIOLOGIC MOVEMENT? | When mild to moderate forces are applied, it acts as a stimulus to initiate cellular resorption and deposition of bone |
What is PATHOLOGIC MOVEMENT? | excessive application of force results in necrosis of periodontal tissues on the pressure side and lack of bone deposition on the tension side |
What cellular activity occurs on the TENSION side of a tooth? | bone deposition |
What cellular activity occurs on the PRESSURE side of a tooth? | Bone resorption |
What is the PRESURE SIDE of the tooth | that in the direction of tooth movement |
Where does the greatest amount of alveolar remodeling occur during tipping motions? | near the crest |
What is the danger of intrusional forces to treat supraclusion? | necrosis of PDL, pulpal necrosis |
How is rotation best accomplished | BY LIGHT FORCES AND INTERMITTENT APPLICATION |
What are the 6 basic orthodontic movements? | 1. tipping 2. radicular (root) 3. translation (bodily) 4. rotation (torsion) 5. extrusion 6. intrusion |
Which is the easiest orthodontic movement? | extrusion, then tipping |
Which is the hardest orthodontic movement? | intrusion |
Where is the center of rotation or FULCRUM in tipping? | at the junction of the middle and apical thirds of the root |
What is radicular movement? | another form of tipping where the apex moves the greatest distance rather than the crown and the fulcrum is at the junction of the cervical and middle thirds of the root |
What is the order from easiest to hardest, of orthodontic movements? | extrusion, tipping, radicular, rotation, translation, intrusion |
What is a challenge associated with rotational tooth movement? | recoil |
What can be done to help counteract recoil from rotation movements? | apply lighter pressure over a longer time period AND use alternating periods of movement and stabilization |
What is a risk of extrusion? | avulsion |
Is recoil typically problematic after intrusion tooth movement? | no |
What is ANCHORAGE? | stable foundation to which an orthodontic appliance is attached |
What factors contribute to resistance of movement of the anchorage unit? | root surface area quality of root alveolus surface area quality of alveolus leverage of appliance type of movement direction of force |
What are the 5 types of orthodontic anchorage? | 1. simple 2. reinforced 3.intermaxillary 4. extraoral 5. reciprocal |
What is SIMPLE ANCHORAGE? | An advantage of at least 2:1 (anchorage:target) is utilized with an appliance in the same dental arch |
What is REINFORCED ANCHORAGE? | use of planes and stationary reinforcement to augment stability of the anchorage by allowing part of the resistance to e transferred from the teeth to paradental tissue |
What are 2 different applications of force? | intermittent and continuous |
What type of force does an inclined plane provide? | intermittent |
When is intermittent force more effective? | When recoil is anticipated |
What is the maximal force that should be applied? What guides that number? | <20 g/cm2, <20 mm HG, <0.5 oz/cm2 force must remain below that of capillary blood pressure |
What are the 2 basic types of orthodontic appliances? | removable and fixed |
What is the main disadvantage of fixed orthodontic appliances? | need greater hygiene care |
What are advantages of fixed orthodontic appliances? | greater security of the applied force less bulky improved precision |
What are the 3 basic types of orthodontic wire? | round rectangular braided |
Which type of wire can apply torquing forces with greatest accuracy? | rectangular wire |
Which type of wire is the most flexible? | braided |
What types of instruments can be used to create bends in orthodontic wire? | birdbeak square howe 3 prong wire-cutter pliers |
How are bends classified? | according to the direction of force |
What are FIRST ORDER bends? | in the horizontal plane: in-and-out bends |
What are SECOND ORDER bends? | in the vertical plane: up-and-down bends |
What are THIRD ORDER bends? What are 3 types? | produce a torque force 1. single-tooth torque 2. anterior torque 3. posterior torque |
What are open coil springs used for? | compression |
What are closed coil springs used for? | traction |
What are 5 types of kick springs? | finger cantilever T W Z |
With fixed appliances, what are springs used for? | tipping |
How does one effect a more gentle force w/springs? | longer wire with more helical loops |
What is an orthodontic band? | flattened piece of metal constructed as a ring to fit around the clinical crown of a tooth and be cemented in place |
What are the 4 most common types of elastics used in veterinary orthodontics? | rings ligatures tubes chains |
What spacing patterns are available in elastic chains? Which is most practical in veterinary work? | long filament short filament continuous filament ** |
What are "K" modules? | Individual filaments with only 2 attachment sites: provide continual gentle force for long periods of time |
What distance are most expansion screws designs to create? | 0.18-0.2 mm movement per quarter turn |
What is the typical width of the PDL space in animals? | 0.15 mm (small animals, older animals) to 0.3 mm |
Application of force should be calculated to what proportion of the PDL space to prevent injury? | 65% |
What is an INCLINE PLANE? | Appliance designed to make contact with the cusps or incisal edges of the teeth of the opposing occlusion to stimulate tooth movement |
What provides the movement force for an incline plane? | muscles of mastication |
What is a BITE PLANE? | an incline plane designed to prevent occlusal closure |
At what angle should the plane face apically? | 60 degrees |
What is a MANN INCLINE PLANE? | A cast fixed appliance that is anchored to the upper canine teeth with a telescoping support bar between the two which allows for skeletal growth |
What is an INCISOR CAPPING plane? | covers a group of incisors (usually mandibular) to move the opposing incisor teeth |
What is ODONTOPLASTIC STRIPPING? | The process of reducing the interproximal contacts using abrasive strips or thin-fluted burs |
What 2 types of appliances can provide extruding movements in combination with tipping for partially open cross bite? | labial maxillary arch bar and elastics AND mandibular brackets and elastic chains |
When SHOULDN'T elastic ligature ties be used for maxillary or mandibular inclinations or verisons? | when there is already crowding |
What is a potential complication with using elastic ligature ties? | embrication b/c it results in mesial or distal movement of adjacent anchor teeth |
Why is it difficult to stebilize mandibular central incisors after tilting or extrusion? | influences of adjacent fibrous attachment of the mandibular symphysis which may partially encompass them |
What is the main disadvantage of mandibular or maxillary incisal incline planes? | typically block the bite open until they are removed or movement is complete |
What is the typical adjustment and frequency for maxillary expansion screw appliances? | 1/4 turn q3 days |
How can a posterior cross bite be corrected? | expansion screw appliance on maxillary 4th premolar + a lingual arch bar w/elastics to pull mandibular molar lingually |
How long must the bite be blocked open during correction of posterior cross bite? | 2-3 weeks |
What complications can arise during attempts to correct posterior cross bite? | open bite may allow supereruption, drifting, problems with TMJ, special dietary care required |
What is a common result of using expansion screw device for base narrow mandibular canines? | bodily movement of the canines rather than tipping, may spread the mandibular symphysis |
Where should the bracket be attached on the labial surface of the maxillary canine to effect a distal tipping movement of that tooth? | middle to coronal third with a slight mesial shift |
What chain adjustments are made to effect distal tipping of the maxillary canine? | tighten 1-2 notches for the first 7-10 days. As the tooth begins to move, tighten only 2-3 notches at a time |
How can distal inclination of maxillary canine teeth be corrected? | maxillary band or sleeve crown with a kick spring |
How long should the retainer be left on after correction of a distally inclined maxillary canine tooth? | 4-6 weeks (these teeth have a strong tendency to recoil) |
What are the 3 basic tx options for class II malocclusions? | preventive extraction preventive crown amputation and pulp capping corrective orthodontic incline plane |
What are the 3 basic tx options for class III malocclusions w/mesiolingual mandibular cuspid malocclusion | preventive extraction preventive crown amputation + pulp cap corrective orthodontic incline plane |
How should an impression tray fit relative to the structures to be captured? | should extend about 1/4 inch beyond structures in all directions |
What is the disadvantage of using a tray that is too large? | more flexibility in the impression = diminished accuracy |
How does water temp affect the setting time of alginate? | cool water slows setting time warm water speeds setting time |
Within what time frame should alginate impressions be poured into models? | 30 minutes |
Where should the wax block be placed to obtain a bite registration? | in the area of the mandibular right 4th premolar |
What material is preferred for cementing brackets to teeth? | composite resin cements |
How long are retainers needed after simple movements? | 2-6 weeks |
How long are retainers needed after difficult movements? | 4-12 weeks |
What are 4 principal areas where complications occur from orthodontic correction? | 1. crestal alveolar bone 2. root structure 3. PDL 4. pulp |
What are 5 other orthodontic complications? | 1. tooth discoloration 2. appliance associated soft tissue trauma 3. hygiene problems 4. contact allergy 5. elastic slippage |
What changes affect root structure during orthodontic tx? | resorption is usually repaired by cementum deposition, but may persist to a clinically sigificant degree |
Which teeth are more prone to root resorption resulting from orthodontic movement | endodontically treated teeth teeth w/pointed apices dilacerated roots hx of trauma severe periodontal dz use of excessive or prolonged forces |
What factor plays a major role in root resorption? | root contact with a cortical bone plate |
What does excessive tooth mobility during orthodontic correction indicate? | excessive force of movement |
What effect does the use of steroids or NSAIDs have on orthodontic movement | analgesia, but may slow movement |
What happens if excessive force results in ischemic necrosis of part of the PDL | cementum comes in direct contact with bone-->ankylosis |