Essentials of Orthodontics textbook Flashcards

Question

MOCDO

Answer 1

Missing teeth Overjet Crossbite Displacement Overbite

Answer 2

Developed to measure the success of ortho tx. Difference between PAR scores at the start and upon completion of treatment can be calculated, and from this a percentage change in PAR score, which is a reflection of the success of tx.

Answer 3

Index of complexity, outcome and need IOTN + PAR

Answer 4

central incisors - 12-16 lateral incisors - 13-16 canines - 15-18 first molars - 14-17 second molars - 16-23

Answer 5

central incisors - 6/7 lateral incisors - 7/8 canines - 18/20 first molars - 12/15 second molars - 24/36

Answer 6

Central incisors - 3-4 Lateral incisors - 3-4 Canines - 4-5 First premolars - 21-24 Second premolars - 27-30 First molars - around birth Second molars - 30-36 Third molars - 96-120

Answer 7

Central incisors - 3-4 Lateral incisors - 10-12 Canines - 4-5 First premolars - 18-21 Second premolars - 24-27 First molars - Around birth Second premolars - 30-36 Third molars - 84-108

Answer 8

Central incisors - 6-7 Lateral incisors - 7-8 Canines - 9-10 First premolars - 10-12 Second premolars - 11-12 First molars - 5-6 Second molars - 12-13 Third molars - 17-25

Answer 9

Central incisors - 7-8 Lateral incisors - 8-9 Canines - 11-12 First premolars - 10-11 Second premolars - 10-12 First molars - 5-6 Second molars - 12-13 Third molars - 17-25

Answer 10

The difference in widths --> leeway space (in general 1-1.5mm in mandible and 2-2.5mm in maxilla) Arch width is measured across the arch between the lingual cusps of the second deciduous molars or second premolars. Between the ages 3-18yrs 2-3mm increase occurs.

Answer 11

Screening - 10yrs maxillary canines palpable in 70% of cases - 11yrs maxillary canines palpable in 95% of cases Eruption cyst - accumulation of fluid/blood in the follicular space overlying the crown of an erupting tooth - usually rupture spontaneously Failed eruption - Disruption in normal sequence of eruption - Asymmetry in eruption pattern between contralateral teeth. If a tooth on one side of the arch has erupted and 6 months later there is still no sign -- radiographs

Answer 12

Early loss of teeth deciduous canine/first molar - centreline shift. consider contralateral extn. deciduous second molar - permanent first molar will drift forwards

Answer 13

Balancing - the extn of contralateral tooth. Centreline problems. Compensating - removal of equivalent opposing tooth. maintain occlusal relationship between arches.

Answer 14

Tooth fails to achieve or maintain occlusal relationship with adjacent or opposing teeth. 1-9% children

Answer 15

impaction of first permanent molar against second deciduous molars occurs in approx 2-6% cases and is indicative of crowding. mild cases can be managed with by tightening a brass separating wire around the contact point between two teeth over a period of about 2 months. severe cases can be dealt with using an appliance.

Answer 16

Distortion or bend in the root of a tooth. Affects upper central/lateral incisor typically. There appears to be 2 distinct aetiologies: 1. developmental. usually affects isolated central incisor. F>M. Crown of the affected tooth is turned upward and labially. 2. Trauma. Intrusion of a deciduous incisor leads to displacement of underlying developing permanent tooth germ. Characteristically, that causes the developing permanent tooth crown to be deflected palatally, and the enamel and dentine forming at the time of the injury are disturbed, giving rise to hypoplasia. management: crown is exposed surgically and traction is applied to align the tooth, provided that the root apex will be sited within cancellous bone at the completion of crown alignment.

Answer 17

Additional to the normal series. 2% in permanent dentition. 1% of primary dentition. Morphology 1. Supplemental. resembles a tooth. 2. Conical. conical supernumerary most often occurs between upper central incisors. Most commonly associated with displacement of the adjacent teeth, can also cause failure of eruption or not affect the other teeth. 3. Tuberculate: type is described as being barrel shaped, but usually any supernumerary which does not fall into the conical or supplemental categories. associated with failure of eruption. 4. Odontome: variant is rare. Both a compound (conglomeration of small tooth like structures) and complex (amorphous mass of enamel and dentine) Failure of eruption common reason for non-present maxillary central incisor Displacement associated with displacement or rotation of an erupted permanent tooth. management involves removal of supernumerary tooth then FA. Crowding Supplemental type. Remove most displaced tooth. No effect incidental finding

Answer 18

1st molars are rarely the first tooth of choice for extn as their position within the arch means that little space is provided anteriorly for the relief of crowding or correct of incisor relationship. Rules - if dentition is uncrowded extn of 1st permanent molars should be avoided - maxilla there is a greater tendency for mesial drift and so the timing of extn of upper 1st molar is less critical In the lower arch, a good spontaneous result is more likely if: - lower 2nd molar has developed - the angle between the long axis of the crypt of the lower second molar and the first permanent molar is between 15 and 30 - a crypt of the second molar overlaps with the root of the first molar

Answer 19

98% of 6yr olds 49% of 11yr olds 7% 12-18yr olds Factors: - Physiological - Familial - Small teeth in large jaws - Missing teeth - Midline supernumerary - Proclination of upper labial segment In cases where the MD is >3mm, it may be necessary to consider appliance tx to approximate the central incisors to provide space for the laterals and canines to erupt.

Answer 20

Deciduous dentition CLP Craniofacial abnormalities Mixed dentition Severe CIII skeletal problems Delayed eruption of permanent incisors Presence of supplemental incisors Impaction of 1st perm molars First perm molars of poor prognosis Ectopic canines Hypodontia Marked mandibular displacement patients with medical problems pathology

Answer 21

Intramembranous osiffication - formation of bone in a membrane Endochrondral ossification - bony replacement of a cartilagenous model

Answer 22

complex structure including maxilla, palatal, zygomatic, ethmoid, vomer and nasal bones. Separate bones join with each other and the anterior cranial base at sutures. until the age of 7, growth of the maxillary complex occurs in downwards and forwards displacement and by drift and remodelling. As the growth of the brain and calvarium slows, so does the maxillary growth. Forward displacement of the maxillary complex allows space for the maxilla to grow backwards, lengthening the dental arch posteriorly in the area of the tuberosities, allowing room for the permanent molars to erupt. Ortho interventions to advance the maxilla, eg., protraction head gear in Class III cases, are reported to be more successful before the age of 10 when the sutures around the maxilla are more amenable to displacement. Interventions to expand the maxilla by RME are reported to be more successful before the age of 16.

Answer 23

PDL consists of cells surrounded by type 1 collagen and oxytalan fibres and a ground substance consisting of proteoglycans and glycoproteins. fibroblasts are responsible for producing and degrading the PDL fibres Cementoblasts are responsible for cementum osteoblasts are responsible for bone production and coordination of bone deposition and resorption osteoclasts are responsible for bone resorption cells rests of Malassez are responsible for dealing with dead cells and debris

Answer 24

Osteoblasts - production of bone. recruit and activate osteoclasts. balance been bone resorption and deposition, controlled by osteoblast. become surrounded by mineralised bone and become osteocytes. Osteocytes - continue to communicate with each other via cytoplasmic extensions in canaliculi in the bone. responsible to detecting mechanical load on bone. Osteoclasts - large multinucleate cells responsible for resorption of bone. Found on the bone surface undergoing active resorption in pits called Howship's Lacunae.

Answer 25

application of mechanical load affects PDL by causing fluid movement in PDL space and by stretching and compressing the collagen fibres and ECM. this leads to deformation of alveolar bone. this distortion in the pdl and alveolar bone are detected by cells which are connected to ECM by proteins known as integrins in their cell walls. 4 basic stages of tooth movement: 1. matrix strain and fluid flow in the pdl and alveolar bone 2. cell strain, secondary to matrix strain and fluid flow 3. cell activation and differentiation 4. remodelling of the pdl and alveolar bone

Answer 26

group of growth factors known to induce formation of bone and cartilage bone morphogenetic proteins

Answer 27

Enzyme in the bone remodelling and resorption expressed in osteoclasts cathepsin K

Answer 28

Colony stimulating facotr (macrophage CSF) polypeptide growth factor found in bone matrix and produced by osteoblasts. acts directly on osteoclast precursor cells to control proliferation and differentiation into osteoclasts

Answer 29

interleukin 1 potent stimulator of bone resorption and inhibitor of bone deposition

Answer 30

matrix metalloproteinases range of enzymes produced to break down unmineralised ECM

Answer 31

produced by osteoblasts in response to RANKL, decrease the activity of osteoclasts to regulate bone resorption

Answer 32

Mediator of bone resorption. produced in sites of inflammation. produced by cells in response to mechanical loading. inc production of intracellular messengers.

Answer 33

produced by osteoblasts. stimulatory factor for differentiation, fusion, activation and survival of osteoclasts.

Answer 34

Produced by various cell types to bind to MMPs to inhibit or reduce their activity

Answer 35

1. mechanical loading causes strain in ECM of PDL and in alveolar bone causing fluid flow 2. strain in ECM is sensed by PDL cells due to their connection to ecm via integrins. osteocytes in the bone also sense the mechanical force by fluid flow through the canaliculi. 3. osteocytes respond to mechanical deformation by producing BMPs and other cytokines which activate osteoblasts. fibroblasts produce MMPs. Osteoblasts respond by producing PGE-2 and leukotrienes. 4. osteoblast production of PGE-2 and leukotrienes leads to an elevation of intracell messengers. cause osteoblasts to produce IL-1 and CSF-1 and increase in receptor activator of nuclear factor. 5. IL-1 is produced by osteoblasts and macrophages also increases the production of RANKL by osteoblast. 6. RANK L and CSF 1 cause increased attraction and proliferation of blood monocytes which fuse to form osteoclasts. RANKL also stimulates the osteoclasts to become more active. 7. osteoblasts bunch up to expose the underlying osteoid and produce MMPs to degrade the osteoid and to give osteoclasts the access to the underlying mineralised bone. osteoblasts also produce OPN which causes osteoclasts to attach to the exposed bone surface 8. osteoclasts resorb the bone by excreting hydrogen ions into the matrix, softening the hydroxyapatite crystals, then use proteases such as Cathepsin K to break down the ECM 9. Osteoblasts also produce inhibitors of some enzymes and cytokines (TIMPs and OPG to ensure that bone resorption is carefully controlled)

Answer 36

1. in areas of tension, osteoblasts are flattened and the osteoid remains unexposed 2. cells in the pdl increase the amount of a specific secondary messenger (ERK in response to tension) 3. ERK signalling induces the expression of RUNX-2 which in turn causes an increase in osteoblast number, possibly by inducing differentiation of fibroblasts into osteoblasts. 4. osteoblasts clump into groups, secreting collagen and other proteins composing the organic matrix, then produce hydroxyapatite, which mineralises the matrix resulting in new bone

Answer 37

tipping --50-75 bodily movement --100-150 root uprighting --75-125 extrusion --50-100 intrusion --15-25

Answer 38

external apical root resorption is a complex inflammatory process that occurs in virtually all patients undergoing treatment. apical portion of root is removed by odontoclast

Answer 39

facial development begins a 4wks (5 swellings - frontonasal, 2 maxillary, 2 mandibular around the stomodeum (primitive mouth)) maxilla and mandible derive from the first pharyngeal arch into which cranial neural crest cells have migrated bone formation occurs by either intramembranous or endochondral ossification bone growth occurs by remodelling and displacement calvarium ossifies intramembranously, closely following the growth of the brain. growth is complete at 7yrs. cranial base ossifies endochondrally. growth at the spheno-occipital synchondrosis occurs in 2 directions until the mid teens. maxilla and mandible ossify intramembranously and undergo complex patterns of remodelling. displaced forwards and downwards in relation to cranial base. growth occurs posteriorly at the tuberosities (maxilla) and ramus (mandible) to accommodate the permanent dentition. the mandible experiences rotational growth and most individuals having an upward and forward direction of rotation. facial growth continues at low level in the adult. growth continues for longer in boys in the AP and V dimensions.

Essentials of Orthodontics textbook Flashcards

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