orthodontics Flashcards

Question

JVD 2023. Marissa Berman, Maria Soltero-Rivera, Amy J Fulton Scanlan. Prevalence of Dental and Skeletal Malocclusions in Mesaticephalic and Dolichocephalic Dogs - a Retrospective Study (2015-2018). How effective was orthodontic therapy in treating MAL?

Answer 1

55/74 (74%) dogs with **deciduous malocclusions** underwent interceptive orthodontics: * 45/55 (82%) dogs still presented with permanent malocclusion [32/45 (71%) proceeded with Tx for the adult malocclusion] * 4/55 (7%) dogs developed a normal adult occlusion * 6/55 (11%) did not return for follow-up. 62/198 (31%) dogs with **permanent malocclusions** had atraumatic malocclusion and no treatment was indicated for their permanent dentition. 85/136 (62.5%) dogs returned for treatment of their traumatic malocclusion. 5/85 (6%) treated dogs experienced complications: * 3 - dehiscense after extractions * 1 failed VPT (underwent RCT) * 1 Ortho appliance lost (not requiring further Tx)

Answer 2

* mild (≥ 50% of the crown of the mandibular canine was mesial to the occlusal maxillary canine from the lateral perspective) * moderate (the mandibular and maxillary canine teeth were in the same plane when viewed from a lateral position) * severe (≥ 50% of the mandibular canine was distal to the opposing maxillary canine when viewed from a lateral position) ## Footnote *"Assessment of Extractions of Deciduous Mandibular Canine Teeth to Correct Linguoversion Malocclusion in 17 Dogs". Kirk Herrmann, Kendall Taney. JVD 2022.*

Answer 3

9/17 (52.9%) total * 6/6 (100%) MAL1 * 3/11 (27.27%) MAL2 1/1 (100%) mild MAL2 2/6 (33.3%) moderate MAL2 0/4 (0%) severe MAL2 ## Footnote *"Assessment of Extractions of Deciduous Mandibular Canine Teeth to Correct Linguoversion Malocclusion in 17 Dogs". Kirk Herrmann, Kendall Taney. JVD 2022.*

Answer 4

MAL1: 49-100% MAL2: 27-49% mild MAL2: 49-100% moderate MAL2: 33.3-49% severe MAL2: 0-49% ## Footnote *"Assessment of Extractions of Deciduous Mandibular Canine Teeth to Correct Linguoversion Malocclusion in 17 Dogs". Kirk Herrmann, Kendall Taney. JVD 2022.* *“Outcome of Surgical Extraction of Linguoverted Deciduous Mandibular Canine Teeth, Performed as an Interceptive Orthodontic Procedure in Puppies, on Permanent Occlusion”. Piotr Godziebiewski, Norman Johnston, Susan Thorne, Vicki J. Adams . JVD 2023.*

Answer 5

* 49% permanent normocclusion * 51% permanent malocclusion requiring treatment MAL1 or MAL2 at time of surgery was not associated with the outcome. * 32/77 (42%) MAL1 * 45/77 (58%) MAL2 Age at the time of surgery was not associated with outcome. * 33/77 (43%) dogs had surgery at or before 12 weeks of age * 44/77 (57%) dogs had surgery after 12 weeks of age ## Footnote *“Outcome of Surgical Extraction of Linguoverted Deciduous Mandibular Canine Teeth, Performed as an Interceptive Orthodontic Procedure in Puppies, on Permanent Occlusion”. Piotr Godziebiewski, Norman Johnston, Susan Thorne, Vicki J. Adams . JVD 2023.*

Answer 6

28 dogs with MAL1. permanent normocclusion: * 78.6% (22/28) total * 77.3% (17/22) in dogs with bilateral linguoversion * 83.3% (5/6) in dogs with unilateral linguoversion ## Footnote *"Outcome of Permanent Canine Teeth Following Extraction of Linguoverted Deciduous Mandibular Canine Teeth in 28 Dogs”. Davin Ringen, Naomi Hoyer, Patrick Vall. JVD 2024.*

Answer 7

6/28 (21.4%) dogs had permanent LMC. * 5/6 had gingivectomy and gingivoplasty to correct the permanent LMC * 1/6 the owner declined treatment ## Footnote *"Outcome of Permanent Canine Teeth Following Extraction of Linguoverted Deciduous Mandibular Canine Teeth in 28 Dogs”. Davin Ringen, Naomi Hoyer, Patrick Vall. JVD 2024.*

Answer 8

Doliocephlic breeds Crossbite (CB): a malocclusion in which a mandibular tooth/teeth have a more buccal or labial position than the antagonist maxillary tooth. Similar to posterior crossbite in human terminology. Rostral crossbite (CB/R): One or more of the mandibular incisor teeth is labial to the opposing maxillary incisor teeth when the mouth is closed. Caudal crossbite (CB/C): One or more of the mandibular cheek teeth is buccal to the opposing maxillary cheek teeth when the mouth is closed.

Answer 9

any deviation from normal occlusion

Answer 10

upper and lower incisors meet edge to edge

Answer 11

Abfraction lesions are non‐carious cervical lesions thought to be caused by biomechanical loading forces (flexing and stress) so that the enamel separates from the inner dentin layer. Mechanical microfractures from abfraction weakens the cervical tooth structure and makes it much more susceptible to loss of tooth structure via abrasion.

Answer 12

position of mandible when there is maximum interdigitation and occlusal contacts b/w max and mand teeth

Answer 13

* tipping of mesioverted maxillary canine with elastic chain * tipping of labioverted mandibular canine with a lingual arch bar for anchorage

Answer 14

dilacerated roots

Answer 15

* recommended: 25% reduction of rest length * in this cat: 20% maxillary, 10% mandibular (moved second) * ‘‘Snowman’’ technique: composite material is used to make an anchorage point that takes advantage of increased leverage forces due to increased crown length (placed on the coronal aspect). can decrease elastic length reduction from 25% to 10%

Answer 16

* 2-6 weeks for simple movements * 4-12 weeks for complex movements

Answer 17

* 35-60 g for tipping * 5 g force for the lips * 5-10 g force for the tongue

Answer 18

* Resolves pain from trauma * Allows independent growth of mandibles to their genetic potential.

Answer 19

* Distraction osteogenesis * Orthodontic movement (elastomeric chain, inclined plane, crown extension) * Crown reduction with vital pulp therapy

Answer 20

* The mandibular canine occupies ~80% of the cross-sectional diameter of the rostral mandible. Loss of the mandibular canine may add to decreased function in dogs with an already shortened mandible. * If the mandibular canine tooth causes traumatic contact on the palatal aspect of its maxillary counterpart, the maxillary canine may be extracted, provided that the trauma point is not occurring so medially that extraction of the maxillary canine tooth might not solve the problem. * Without the maxillary canine tooth and alveolar bone in the area, the mandibular canine is allowed space to continue eruption and move labially. * Extracting the maxillary canine allows to salvage the structure and function of the mandibular canine, avoid complications associated with mandibular canine extraction, and negate the need for lifelong follow-up of endodontic therapy.

Answer 21

As successful as conventional orthodontics. Due to the position of 204 – directly buccal to 304 contact so nowhere for 304 to go without hitting 204.

Answer 22

* Distal tipping of 104/204 by elastic chain appliance * followed by incline plane for buccal/labial movement of 304/404 Applied in the same procedure

Answer 23

* apical 1/3 on the anchorage unit (P4/M1) * middle third on the canine. to increase leverage for distal tipping of the canine

Answer 24

* Stimulate frontal resorption * avoid PDL necrosis and undermining resorption.

Answer 25

60 degrees (to create a light tipping force while reducing potential for intrusion)

Answer 26

So it wouldn’t anchor the canines and would allow their movement.

Answer 27

normal relationship of the maxillary incisors overlapping the mandibular incisors whose incisal edges rest on or near the cingulum on the lingual surfaces of the maxillary incisors

Answer 28

**overbite** is the *vertical component* **overjet** is the*horizontal component* of abnormal overlapping incisors

Answer 29

Irregular arranged teeth within an arch due to a lack of space (crowding) typically seen in mandibular incisors and maxillary premolars in brachycephalic breeds. Rotated, tipped, supraerupted (supraclusion), infraerupted (infraclusion), and displaced teeth are not uncommon in embrication.

Answer 30

* version is the tipping of a tooth crown * displacement is bodily movement in one direction or another

Answer 31

prevent normal growth of the mandible or maxilla depeding on the interlock

Answer 32

* interceptive * preventive * corrective

Answer 33

extraction or recontouring (crown reduction) of primary or permanent teeth that are contributing or will contribute to alignment problems of the permanent dentition

Answer 34

**4-8 weeks (no later than 12)** to allow any potential normalization of the growth pattern prior to eruption of the successional teeth and re‐interlocking of the bite pattern. *"Incidence of enamel defects on permanent canine teeth following extraction of linguoverted mandibular deciduous canine teeth in dogs". Charles L. Felz, Boaz Arzi, Kendall Taney, Katherine Block. FVETS 2024.* * enamel defects developed in: 10.4% dogs aged 11-12 weeks at the time of extraction. 30.7% dogs aged 8–10 weeks at the time of extraction. this may suggest extracting deciduous mandibular canine teeth when the dog is older than 11 weeks. * It is unknown if delaying extractions until 11–12 weeks of age or older will affect the ability of the jaws to reach full genetic growth potential due to continued dental interlock and potential interference with skull development. * A delay in extractions also has the potential for ongoing palatal trauma and patient discomfort.

Answer 35

Preventive orthodontics: evaluation and elimination of conditions that may lead to irregularities in the developing or mature occlusal complex. * Occlusal assessment and supervision: supervision of timely primary dental exfoliation and permanent dental eruption (assisting exfoliation or eruption is an interceptive orthodontic action) * Space control: treatment of traumatic, congenital, or hereditary anomalies, as well as dentally destructive diseases (caries, dental resorption, periodontal disease, etc.) and maintenance of dentally voided spaces * Behavioral control: therapy to manage deportment, which can affect occlusion **Usually does not actually include doing anything**

Answer 36

Corrective orthodontics: performing orthodontic treatment for an existing problem. * treatment phase * retainer phase

Answer 37

When a light to mild force is applied it acts as a stimulus to initiate cellular activity resorption and deposition of bone which is termed the physiologic movement. When these pressures are exceeded with a heavy force there will be necrosis of periodontal tissues on the pressure side and poor to no deposition of bone on the traction side which is labeled pathologic movement.

Answer 38

application of an orthodontic force generates a pressure side and a tension side within the PDL * On the pressure side (direction of tooth movement), the PDL is compressed -> an increase in the capillary pressure and blood supply at pressure points -> increased mobilization of fibroblasts, cementoblasts, osteoblasts, and osteoclasts to the area -> resorption and remodeling of bone and periodontal tissues. * On the tension side (away from the direction of tooth movement), the PDL is stretched -> widening of the PDL space -> capillary blood flow and cellular activity increases -> deposition of new bone along the traction areas of the lamina dura

Answer 39

* On the pressure side (direction of tooth movement) the PDL is compressed -> increase in capillary pressure and blood supply at pressure points, initially the alveolar crest -> increased mobilization of fibroblasts, cementoblasts, osteoblasts, and osteoclasts to the area -> resorption and remodeling of bone and periodontal tissues. * On the tension side (away from the direction of tooth movement) the PDL is stretched -> widening of the periodontal membrane space -> capillary blood flow and cellular activity increases -> deposition of new bone along the traction areas of the lamina dura.

Answer 40

* phase 1 - initial movment lasts 24-48 hours. rapid transpositional movement followed by slower "creep" movement. * Phase 2 - lag phase lasts 20-30 days. the halt in tooth movement is due to hyalinization of the PDL caused by vascular obliteration and subsequent local necrosis. Macrophages remodel the necrotic and hyalinized PDL * Phase 3 and 4 - post-lag phases phase where real tooth movement occurs by osseous remodelling

Answer 41

* tipping * radicular (root) * translation (bodily) * rotation (torsion) * extrusion * intrusion

Answer 42

Intrusion: 15-25 g Tipping: 50-75 g Rotation: 50-75 g Extrusion: 50-75 g Translation: 100-150 g

Answer 43

Tooth movement stimulates resorption and deposition of bone. Osteoclasts, which originate in the bone marrow, where they are protected from the site of periodontal inflammation, tend to be unaffected by infection and continue to reabsorb bone. Osteoblasts are of vascular origin and are strongly suppressed by inflammatory disease. In periodontal disease situations, bone resorption is normal but bone formation is inhibited, and the resultant loss of alveolar supporting bone is exaggerated. Orthodontics, although a useful adjunct for enhancing periodontal health if undertaken in the presence of active periodontal disease, is invariably disastrous.

Answer 44

After application of a continuous load, tooth movement can be classified into three distinct phases: * initial strain: displacement of approximately 0.4-0.9 mm within the first week as a result of PDL compression, bone strain, and extrusion. * the lag phase: can vary from 1-3 weeks depending on the age of the patient, the degree of PDL necrosis (hyalinization), and the density of the alveolar bone. Undermining resorption removes the necrotic tissue, vitality is restored * progressive tooth movement

Answer 45

Within 4 hours of sustained pressure, cyclic adenosine monophosphate (cAMP), an important ingredient in cell differentiation, is elevated -> stimulation of osteoblasts and osteoclasts -> alveolar bone resorption at areas of increased PDL pressure, osteoblasts lay down new bone in areas of PDL tension.

Answer 46

Anchorage is the resistance to reaction provided by other teeth or structures. The desired result is to maximize the target tooth movement and minimize the undesirable side effects. The anchorage value of a tooth is a function of its root surface area. For significant differential tooth movement, the ratio of PDL area in the anchorage unit to the PDL area in the target (moving) unit should be at least 2:1 without friction. With the frictional component designed in the appliance, the PDL ratio should be a minimum of 4:1.

Answer 47

Center of resistance: the approximate geometric midpoint of the embedded portion of the tooth root or midway between the alveolar crest and the root apex. Center of rotation: the point around which rotation occurs when a tooth is being moved. * In translation, the center of rotation is at infinity * In tooth rotation, the center of rotation is near the center of resistance * The stress level is zero at the center of rotation during tooth movement The center of rotation could be equated to the fulcrum if the tooth were to be regarded as a simple lever. The moment created by application of a force away from the center of resistance results in rotation around the center of resistance. By varying the distance, a larger moment can be created without increasing the force magnitude. The moment arm is the distance between the point of force application and the center of resistance.

Answer 48

The ratio of cortical to cancellous bone is higher in the mandible than in the maxilla; correspondingly, tooth movement is faster in the maxilla than in the mandible.

Answer 49

2:1 (Wiggs says it is often incorrectly stated as the root surface ratios - however doesn’t elaborate on what IS correct)

Answer 50

* Passive/intermittent force * Continuous force

Answer 51

To prevent damage to the periodontium or tooth, the force should be limited to remain below that of capillary blood pressure: 20–26 g/cm2 of tooth root surface

Answer 52

* Removeable * Fixed

Answer 53

* First-order bends are in the horizontal plane and are in and out bends. * Second-order bends are in the vertical plane and are up and down bends. * Third-order bends are bends that produce a torque force

Answer 54

* simple movement: 2-6 weeks is required. * In more complex movements and those involving torsiversion: 4–12 weeks is recommended. * Occasionally, the actual scissor bite or canine interlock of the occlusion may act as a natural self‐retainer.

Answer 55

it is resorbed and remodels, but usually keeps the same relationship to the tooth - ie. seems to ‘travel’ with the tooth and alveolar crest will be at the same height relative to the tooth after movement.

Answer 56

* direct is applied chairside * indirect is made by a dental lab

Answer 57

mesioverted 104, 204 linguoverted 304, 404 all canines only 75% erupted Diastema between 103/104 and 203/204 was too small to accommodate 304/404.

Answer 58

correcting and establishing comfortable functional occlusion. Owner was warned of hereditary concerns. Options: * CR/XP VPT 304, 404 * orthodontic mvmt 104, 204, 304, 404 * surgical extraction 304, 404. Owner elected combined orthodontics of elastic power chain 104, 204 and inclined plane of 304, 404

Answer 59

* cheaper than other options * designed for specific movement and used in conjunction with power chain * can avoid involving 103, 203 to allow for continued growth of jaws and enlarging of diastema * full eruption of canines not required * dog controls forces as it is intermittent passive force.

Answer 60

* maxillary P4/M1: apical 1/3 of mesial cusp * maxillary canine: middle 1/3 of buccal aspect

Answer 61

measured between 204 and 208, applied to the 204 and 208 composite buttons under tension at 75% of its original length. light to moderate tipping force to prevent PDL necrosis and undermining resorption

Answer 62

60 deg. light intermittent tipping forces of 304/404

Answer 63

Dog was only 6 months old. Took only 2 weeks to achieve normal occlusion. At 1 week button had to be replaced.

Answer 64

* lack of root development and dentinal wall thickening * widening of PDL, periapical lysis * root resorption * furcational crestal bone widening (loss) or loss of interproximal contact between P4 and M1 (suggesting extrusion and/or tipping of anchorage teeth) none present in these teeth.

Answer 65

normally would be 4-6 weeks with masel chain under no tension. however, natural dental interlock of canines provides its own natural retainer so device was removed

Answer 66

* Gingivoplasty +/- alveoloplasty * extraction of 103, 203 * kong ball therapy Fly ball dog (requires full function of incisors and canine teeth). Degree of linguoversion with small diastema made none of these a good option.

Answer 67

the button was placed on the buccal midbody crown surface, in the direction of the intended movement of the tooth. This position would maximize translational movement of the tooth; it was not placed further coronally as the tooth was only mildly mesioverted and less tipping was needed.

Answer 68

MAL2 (mandibular distoclusion) and MAL1/LV 304, 404 resulting in palatal trauma. previous Tx: XSS 704 804 (interceptive orthodontics) to allow for continued jaw growth and stop adverse/unfavorable dental interlock that was impeding jaw growth

Answer 69

Tx options: * Extraction 304/404 * orthodontic movement 304/404 (inclined plane) * CR/XP and VPT 304/404 with odontoplasty of mandibular incisors (increased ability to impinge on the palate after crown reduction of the canine teeth) MTA (mineral trioxide aggregate) * antibacterial * biocompatible * induces dentinal bridge * promotes bone and PDL growth formation

Answer 70

37% (usually). action on dentin: * removes smear layer * dissolves hydroxyapatite crystals and exposes dentinal tubules to allow for micromechanical interlock with dentinal bonding agents odontoplasty removes enamel and exposes dentin. sealant allows time for tertiary dentin to form and prevent bacterial leaching into tubules.

Answer 71

A 15-week-old kitten was presented with MAL2 and bilateral linguoverted deciduous mandibular canine teeth (704, 804) penetrating the mucosa palatal to the deciduous maxillary canine teeth (504, 604) * interceptive orthodontics of 704 & 804 was performed. By 6.5-months of age, the MAL2 was worse, 304 & 404 penetrated the maxillary mucosa. * Tooth extensions were placed, abandoned after 2 weeks due to the challenge of maintaining position in the maxillary 03-04 interdental spaces, potential discomfort associated with rapid tooth movement, traumatic gingivitis, and risks to vitality of the target teeth * took impressions and had removable thermoplastic inclined planes (5 with serial gradations) fabricated: -- a passive intermittent force removeable appliance. -- new appliance about every 10 days over a 3-month period

Answer 72

Advantages over “directly” applied composite inclined planes: * serial gradations of angulations for more gradual tooth movement * elimination of dental trauma from composite adhesions and removals * owner-removable and cleanable appliances * a single anesthetic event required for dental impressions To tip the canine teeth a maximum 20° angle between the tooth axis and IP surface was desirable; minimizing the intrusive forces. * the plane angles on the thermoplastic IP aligners were almost imperceptible, with “soft” contact against the resilient plastic surface. * these gentle angles allowed the mouth to be mostly closed throughout the course of treatment, and may also account for the ready acceptance of the aligners by the cat. * given the distances necessary to tip 304 and 404, and the mouth opening limitations, it appears unlikely that a directly applied composite IP meeting the less than 20° angle could have been constructed

Answer 73

bowing of mandibular incisors which self corrected over time

Answer 74

Retainer: * 2-6 weeks for simple movements * 4-12 weeks for complex movements * or about one half the time it takes to complete the movement The last aligner was used as the retainer for 4 weeks in this cat, allowing time for stabilization of the periodontium and to prevent tooth rebound.

Answer 75

* Cats have <0.1 to 0.3 mm enamel * Dogs have <0.1 to 0.6 mm enamel Etching not only softens the enamel, but removes 0.01 mm.

Answer 76

Tipping causes rotation of a tooth around its center of resistance (CR) located **at the middle of the embedded root**. Coincident to this tipping rotation, is an extruding force exerted distally, and an intruding force, exerted mesially.

Answer 77

no - theoretically but some damage will likely happen due to the forces applied.

Answer 78

The position of the arches in relation to each other when the teeth are in maximum occlusal contact

Answer 79

The most functional unrestrained anatomically retruded position of the heads of the Condyles of the mandible in the Glenoid fossa of the TMJ

Answer 80

The dental arches close too far when the bite in in static occlusion. Typically seen when excessive wear of the teeth occurs allowing excessive closure of the occlusion.

Answer 81

results from genetic malpositioning of teeth or dietary causes involving insufficient attrition

Answer 82

* Compressive * Tensile * Shear * Twisting * Bending

Answer 83

* Initial compression phase * Hyalinization phase (10-20 days) - ligaments that undergo this process (Lag phase) * further tooth movement (Postlag phase)

Answer 84

The active tooth contacts made during mastication and swallowing

Answer 85

Any deviation from normal occlusion

Answer 86

upper and lower incisors meet edge to edge

Answer 87

Contact between maxillary and mandibular teeth; mammals have precise occlusion

Answer 88

The relationship of the teeth when the jaws are closed in centric occlusion Static occlusion can be studied in the actual patient or on an occluded study model and it can be used to classify occlusion

Answer 89

a behavior modification technique using a removable orthodontic device.

Answer 90

* No major jaw length discrepancy should be present. * The diastema between the maxillary I3 and canine teeth should be wide enough to accomodate the mandibular canine tooth in its corrected position * Works best in young dogs with actively erupting teeth. When teeth are only partly erupted, the toy needs only to guide the erupting tooth in the correct direction. Once erupted, the tooth needs to be redirected into a more appropriate position. The time required for correction was longer in the fully erupted teeth. * In less severe cases of mandibular retrognathia, it works if a very large ball is used and it can help tip the teeth rostrally and labially (if mandible is too short)

Answer 91

shape: * round or oval * without ropes or handles (the dogs will take the toy by the easiest way, which is by the rope if it is present) size: * too small will not touch both mandibular canines at the same time, and might be taken too deeply into the mouth * too large a toy (that lies on top of the canine crown tips) might cause intrusive rather than lateral tipping pressure and might be uncomfortable, causing the dog to give up playing * the toy should sit in between and just behind the canine teeth, larger than the distance between the canine teeth, thus applying lateral pressure to the teeth * in some dogs very large toys are needed, because the dog holds objects between its carnassial teeth rather than the canine teeth. In that case the toy needs to be so large that it does not fit between the carnassial teeth, as this is likely to result in some degree of rostral, as well as lateral, tipping of the canine teeth * in selected cases, where rostral as well as lateral tipping is required, carrying the toy between the carnasial teeth can be useful. consistency: * hard rubber, slightly deforming on chewing * too soft a toy is unlikely to create enough pressure and would be rapidly destroyed by chewing * smooth surface to avoid excessive tooth wear

Answer 92

at least 15 minutes of active chewing TID

Answer 93

38 dogs were included. **time required for correction was recorded for 26 dogs, range 2-12 weeks**: * dogs aged 5 months at start of treatment: 2-8 weeks (median 3 weeks) * dogs aged 5.5 months: 2-6 weeks (median 4 weeks) * dogs aged 6 months: 3-4 weeks (median 3.5 weeks) * dogs aged 6.5 months: 2-7 weeks (median 4 weeks) * dogs aged 7-9 months: 5-12 weeks (median 7 weeks) 8 dogs had slight or severe mandibular retroganthia, they had the worst outcome: * 3/8 with slight mandibular retrognathism were corrected in 2-3 weeks * 1/8 was moving slowly (0.5 mm per month) * 1/8 was unilaterally corrected * in 3/8 the canine teeth did not move **Approximately 70-75% dogs experienced correction**. No relapses were reported.

Answer 94

a 7 month old cat with facial swelling, unerupted maxillary canine tooth and a dentigerous cyst * Opened and curetted the cyst, and left it to heal for 1 month to allow the tooth to erupt * It didn’t so orthodontically extruded the canine tooth with a custom invented anchorage device with extrusion force of 50-75g * Managed to get the tooth extruded and it was still present and somewhat healthy at 5 years later * Had abnormal radicular anatomy

Answer 95

Only after application of heavy forces and the movement of teeth for more than 30 days.

Answer 96

* Shetland Sheepdogs * Italian Greyhounds therefore possibly heredity involvement

Answer 97

Contact between maxillary and mandibular teeth; mammals have precise occlusion

Answer 98

The relationship of the teeth when the jaws are closed in centric occlusion. Static occlusion can be studied in the actual patient or on an occluded study model and it can be used to classify occlusion

Answer 99

extrusion tipping radicular (root) rotation (torsion) translation (body) intrusion

Answer 100

stimulated resorption of alveolar bone, widening of PDL space (severe pressure causes undermining resorption, necrosis of PDL and bone) causes elongation of the PDL and apposition of alveolar bone, enlarged blood vessels (severe tension causes resorption of bone and widening of PDL)

Answer 101

widened at the expense of the bone, resulting in angular bone defects without periodontal pockets, tooth becomes loose!

Answer 102

when bone is resorbed by excessive occlusal forces, the body attempts to reinforce it with buttressing bone formation

Answer 103

widened PDL funnel shaped at crest angular defects in the bone with no pocket formation

Answer 104

results from genetic malpositioning of teeth or dietry causes involving insufficient attrition

Answer 105

single rooted teeth: in the junction between the middle 1/3 and apical 1/3 multi-rooted teeth: middle of the inter-radicular bone

Answer 106

* Slightly excessive pressure: resorption of alveolar bone, with a resultant widening of the PDL space. In areas of increased pressure, blood vessels are numerous and reduced in size * Slightly excessive tension: elongation of PDL fibers, apposition of alveolar bone. In areas of increased tension, blood vessles are enlarged. * Greater pressure: compression of PDL fibers produces areas of hyalinization (loss of cells). Subsequent injury to fibroblasts and other connective tissue cells leads to necrosis of areas of the PDL. Vascular changes are also produced: within 30 minutes, impairment and stasis of blood flow occur; at 2-3 hours, blood vessels appear to be packed with erythrocytes, which start to fragment; and between 1-7 days, disintegration of the blood vessel walls and release of the contents into the surrounding tissue occur. In addition, increased resorption of alveolar bone and of the tooth surface occur. * Severe tension: causes widening of the PDL, thrombosis, hemorrhage, tearing of the PDL, and resorption of alveolar bone. * Pressure severe enough to force the root against bone causes necrosis of the PDL and bone. The bone is resorbed from viable PDL adjacent to necrotic areas and from marrow spaces (undermining resorption).

Answer 107

pressure severe enough to force the root against the bone -> hyalinization (loss of cells) -> osteoclasts within adjacent marrow spaces attack the underside of the lamina dura (undermining resorption)

Answer 108

insufficient occlusal forces causes: * thinning of PDL * atrophy of fibers * osteoperosis of bone * reduction in bone height hypofunction from open bite, lack of antagonistic tooth, unilateral chewing

Answer 109

inclined planes [TCE]: * success in 96.6% [98.6%] complete resolution in 71.2% [77.8%] functional resolution in 25.4% [20.8%] * failure in 3.4% [1.4%] adjustments required in: * 31.4% of dogs with IP * 61.1% of dogs with TCE median treatment time * inclined plane: 42 days; MAL2 significantly longer (55 days) than MAL1 (30 days) * TCE: 42.7 days; not associated with MAL class relapse * IP 14.4% * TCE 1.4% ## Footnote *"Success of orthodontic treatment of linguoverted mandibular canine teeth using a direct inclined plane appliance. Frontiers 2023. Taylor et al.*

Answer 110

at the time of appliance removal, complications occurred in 19.4% of dogs. * Gingivitis at the appliance margin in 55.5% (40/72) of dogs * Palatitis deep to the appliance in 16.7% (12/72) of dogs * Enamel fracture in 13 teeth * Enamel-dentin fracture in 3 teeth * Tooth staining in 6 cases 14.4% of the teeth that had initial resolution, had rebound movement that required additional treatment. ## Footnote *"Success of orthodontic treatment of linguoverted mandibular canine teeth using a direct inclined plane appliance. Frontiers 2023. Taylor et al.*

Answer 111

Tipping – a single force applied to the crown of the tooth. Root moves minimally. Uprighting – tipping root back into parallel orientation. Bodily movement/Translation – crown and root moves together an equal distance same direction. To do this the force must pass through the tooths center of resistance. Intrusion or extrusion – movement along the long axis. Rotation – labial/lingual movement around the long axis. Torquing – Moving only the root of the tooth (lingual or labial root torque) to change its inclination. Controlled labiolingual or buccolingual inclination (front-to back angle) of a tooth's root while keeping the crown relatively stable.

Answer 112

Initial phase * rapid tooth movement over a short distance, which then stops (0.4–0.9 mm during the first week) * the extent of tooth movement in this phase is the same for both light and heavy forces * caused by displacement of the tooth in the PDL space and by bending of alveolar bone to some extent Lag phase * little to no tooth movement * formation of hyalinized tissue in the PDL, that must undergo resorption before further tooth movement can occur * duration of the lag phase depends on the amount of force applied. When light forces are applied, the area of hyalinization is small and frontal resorption occurs, whereas larger area of hyalinization occurs with heavy orthodontic forces. * Lighter force = less hyalinized tissue = faster resorption and shorter lag phase. * generally the lag period is 2-3 weeks Post Lag phase * After resorption of the hyalinized tissue tooth movement progresses rapidly. * osteoclasts are formed over a large surface area, directly resorbing the bone surface facing the PDL

Answer 113

MAL prevalence 25.9% MAL3 17.5% (12.8% breed standard, 4.7% not) For single dogs * 33.8% purebred dogs had malocclusions * 20% mixed breed dogs had malocclusions For dogs in litters * 0% purebreds with malocclusion * 23.5% mixed breeds with malocclusions

Answer 114

The inclined plane is required bilaterally in order to prevent the mandible from simply shifting to one side rather than moving the mandibular canine tooth.

Answer 115

* without etching the teeth, acrylic was applied to the maxillary canine and incisor teeth * the patient’s mouth was placed into partial occlusion with the endotracheal tube displaced to one side of the mouth before the acrylic was fully cured -> indentation of the mandibular canine tooth into the acrylic * the indentation demonstrates where to start the inclined plane * the acrylic is allowed to fully cure before being gently removed from the mouth using a luxator * the appliance is shaped outside the mouth using a coarse diamond bur and replaced to confirm positioning and occlusion (without risk of damaging the gingiva or teeth) In order to accomplish the removal of the device prior to bonding to the teeth, only one side can be done at a time.

Answer 116

* the teeth are acid etched * a bonding agent is applied * the splint is placed back on the teeth before light-curing the bonding (curing is done through the acrylic)

Answer 117

Given that enamel development ceases prior to or at the time of tooth eruption, enamel in dogs should be fully developed in permanent teeth 15–31.4 weeks after birth.

Answer 118

when hypoplasia or enamel defects affect only one tooth they are known as a Turner’s tooth or exhibiting Turner’s hypoplasia. ## Footnote *"Incidence of enamel defects on permanent canine teeth following extraction of linguoverted mandibular deciduous canine teeth in dogs". Charles L. Felz, Boaz Arzi, Kendall Taney, Katherine Block. FVETS 2024.*

Answer 119

17.5% dogs exhibited enamel defects affecting 14.6% permanent canine teeth.

Answer 120

37.8% (28/74) dogs required additional treatment to prevent the permanent mandibular canine teeth from causing trauma to the hard palate and gingiva.

Answer 121

Enamel defects developed in permanent canine teeth after extractions of deciduous canines in: * 10.4% of dogs aged 11-12 weeks at the time of extraction * 30.7% of dogs aged 8–10 weeks at the time of extraction Although the association between age at the time of extractions and development of enamel defects was not significant, this may suggest to wait on extracting deciduous mandibular canine teeth until the dog is older than 11 weeks. It is unknown if delaying extractions until 11–12 weeks of age or older will affect the ability of the jaws to reach full genetic growth potential due to continued dental interlock and potential interference with skull development. A delay in extractions also has the potential for ongoing palatal trauma and patient discomfort.

Answer 122

when treating deciduous teeth: * crown extensions would be in place until the deciduous teeth exfoliate with the eruption of permanent dentition * linguoversion of the permanent dentition can occur, and can require further treatment

Answer 123

ideally 6-8 mm of the crown should be exposed (corresponding to roughly 5-6 months of age) to allow sufficient attachment of the extension

Answer 124

the extension should be long enough to engage the outer edge of the palate associated with the maxillary diastema or space distal to the maxillary canine tooth

Answer 125

In mild cases of mandibular canine tooth linguoversion where the tip of the canine crown is interfering with the diastema gingival margin causing gingival irritation and indentation from impaling the soft tissue, gingivectomy and gingivoplasty may be performed to eliminate the soft tissue impediment.

Answer 126

* The resulting GV should be hour-glass shaped, wider dorsally to serve as a “sliding board” to receive the linguoverted canine tooth. * Every effort should be made to maintain the gingival margin and attached gingiva at the maxillary I3 and canine teeth. * Maintenance of the periosteum will enhance epithelialization of the soft tissue defect.

Answer 127

* ball diameter: slightly larger than the space between the mandibular canine teeth * the ball should be firm with a malleable coating that will deform slightly when chewed * frequency and duration of ball therapy: a minimum of 3 times daily for 15 minutes each time

Answer 128

tipping involves crown and root moving in opposite directions, whereas translation requires forces producing movement in the same direction

Answer 129

20 to 26 g/ cm2 Forces greater than the capillary blood pressure of 20 to 26 g/ cm2 could damage tooth and periodontium (ie with active force devices)

Answer 130

Osteoclasts, which originate in the bone marrow, where they are protected from the site of periodontal inflammation, tend to be unaffected by infection and continue to reabsorb bone. Osteoblasts are of vascular origin and are strongly suppressed by inflammatory disease. In periodontal disease situations, bone resorption is normal but bone formation is inhibited, and the resultant loss of alveolar supporting bone is exaggerated. "Orthodontics is invariably disasterous".

Answer 131

Non-steroidal antiinflammatory (NSAIDs) use in orthodontic cases is controversial. Current research indicates that due to their inhibitory effect on prostaglandins which moderate tooth movement, their use can impair the tooth movement process. Recommendations stated in the human literature recommend the use of acetaminophen as an alternative to NSAID use.

Answer 132

The periodontal ligament (PDL) mediates the bony response to pressure applied to the dentition. Tooth movement is primarily a PDL phenomenon.

Answer 133

The bioelectric theory involves the production of piezoelectricity by the deformation of bone, collagen, and fibrous proteins. Electricity is produced in the deformation process and the relaxation process, thereby providing a constant flow of bioelectric energy. The exact mechanism has not been elucidated, but the application of exogenous electrical signals has been known to affect cellular activity

Answer 134

If orthodontic pressure is excessive, sterile necrosis develops in the compressed area of the periodontal ligament. The cells cut off from adequate blood supply die (hyalinisation). The remodeling of bone occurs underneath the necrotic layer, delaying the process of tooth movement several days to weeks. Because the osteoclastic activity is separated from the moving tooth by this necrotic layer of PDL, the process is referred to as ‘‘undermining resorption.’’

Answer 135

1. Initial strain: Displacement of approximately 0.4 to 0.9 mm, which occurs within the first week as a result of PDL compression, bone strain, and extrusion. Compression of the PDL requires 1 to 3 hours. (Accounts for the immediate movement seen after appliance activation Not stable—largely elastic deformation rather than biologic remodeling) 2. Lag phase: Can vary from 1 to 3 weeks. Little to no visible tooth movement Formation of hyalinized (necrotic) PDL areas on the pressure side due to vascular occlusion Removal of necrotic tissue via undermining resorption (osteoclasts recruited from adjacent marrow spaces) Excessive force → more hyalinization → prolonged lag phase 3. Post-lag Phase (Acceleration / Linear phase) Steady, linear tooth movement Frontal resorption on pressure side (osteoclast activity directly adjacent to PDL) Bone apposition on tension side (osteoblast activity) Re-established PDL function Achieved with optimal (light, continuous) forces

Answer 136

the ratio of PDL area in the anchorage unit to the PDL area in the target (moving) unit should be at least 2:1 without friction. With the frictional component designed in the appliance, the PDL ratio should be a minimum of 4:1

Answer 137

Normal capillary pressure Forcess that exceed this will restrict blood supply to the PDL and formation of hyalinized (necrotic) PDL areas on the pressure side due to vascular occlusion

Answer 138

The ratio of cortical to cancellous bone is higher in the mandible than in the maxilla; correspondingly, tooth movement is faster in the maxilla than in the mandible.

Answer 139

tipping: 50 to 75 g. Other forces for reference: translation is 100 to 150 g (50–60 cN). rotation are in the range 50 to 75 g (25–30 cN). extrusion are 50 to 75 g (25–30 cN). intrusion= extremely light forces (15–25 g)

Answer 140

translation is 100 to 150 g (50–60 cN). Other forces for reference: Tipping: 50 to 75 g. rotation are in the range 50 to 75 g (25–30 cN). extrusion are 50 to 75 g (25–30 cN). intrusion= extremely light forces (15–25 g)

Answer 141

The usual retainer period is one half of the amount of time it took for the tooth to reach the desired location.

Answer 142

Outcome Distribution: o 49% (38/77) achieved atraumatic permanent occlusion o 51% (39/77) required further orthodontic treatment  Malocclusion Class: o No significant difference in outcome between class 1 and class 2 malocclusion cases*  Age Factor: o No correlation between age at extraction (mean 13.2 weeks) and outcome *class 1 and 2 mandibular malocclusion at the time of surgery (P = 0.07) so almost significant

Answer 143

Complete resolution of linguoversion in 71.2% of teeth Functional resolution in 25.4% Failure in 3.4%. Median treatment time was 42 (11–174) days Class 2 took significantly longer than Class 1 Class 2 was 55 (16–174) days compared to 30 (11–77) days

Answer 144

45.7% had adjuvant treatement 31.4% of dogs required an anesthetized appliance adjustment

Answer 145

Complications at removal occurred in 19.4% of dogs (16.9% of devices) 13 teeth enamel, 3 enamel dentin fractures 14.4% had rebound movement that required additional treatment

Answer 146

Gingivitis at the appliance margin was seen in 55.5% (40/72) of dogs, and palatitis deep to the appliance was seen in 16.7% (12/72) of dogs

Answer 147

No evaluated risk factors, including the age of the patient at the time of IP application, the number of teeth included in the appliance, the type of malocclusion treated, or the number of days that the appliance was in place, significantly (P > 0.05) affected the outcome.

Answer 148

Only class I 78.6% (22/28) had a normal permanent occlusion. Of these 6 patients, 5 received gingivectomy and gingivoplasty treatment (ie they were sufficiently mild)

Answer 149

Deciduous Incisors 3-4 weeks Canines 3 weeks Premolars 4-12 weeks Permanent: Incisors 3-5 MONTHS Canines 4-6 MONTHS Premolars 4-6 MONTHS Molars - 5-7 MONTHS

Answer 150

Ringen et al: 78.6% (22/28) had a normal permanent occlusion. Berman et al: 18% (10/55) had a normal permanent occlusion... (Berman doesn't specify what class of malocclusion and doesn't techincally specify that it was deciduous canines extracted/permanent mal)

orthodontics Flashcards

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