Ortho Flashcards
(232 cards)
What EO assessments are made for ortho?
Skeletal
- anteroposterior
- vertical
- transverse
Soft Tissue
- lip competence
- incisal display
- lip protrusion
Discuss AP ortho measurements
From side on, pt in natural head position/Frankfort plane parallel, bipalpation of deepest curve of maxilla + mandible
Skeletal
- 1: normal; chin on/up to 2mm behind zero meridian line
- 2: retrusive; chin behind line
- 3: protrusive; chin in front of line
Discuss vertical ortho measurements
Two methods Linear: Lower Ant. Facial Height - using ruler for numerical value - lower 1/3 should = middle 1/3 — glabella-> subnasale -> soft tissue gnathion
Angular: Frankfort Mandibular Plane Angle
- high/obtuse: lines meet before occiput; inc. LAFH
- av.: lines meet @ occiput
- low/acute: lines meet behind occiput; red. LAFH
Discuss transverse ortho measurements
Measured above + behind and in front of pt
Facial centreline: mid-eyebrow, tip of nose, U lip philtre, chin point
Facial asymmetry: usually mandibular
- true: X-bite + mandibular displacement
- common: molar 3, inc. LAFH
Discuss lip assessment for ortho
Morphology: thin, normal, full
Competency:
- competent: meet @ rest w/o muscular effort
- potentially: separated only by proclined UIs (Class 2/1)
- incompetent: don’t meet @ rest; Skeletal 2, inc. LAFH
Coverage: L lip cover 1/3 UIs
Length: alar base to vermillion border; 22-24mm
Discuss intro-arch dental features for ortho assessment
Crowding: dento-alveolar discrepancy
- mild: <4mm
- mod.: 4-8mm
- severe: >8mm
Spacing: dento-alveolar discrepancy
- not usually measured
- qualify where present
- maxillary median diastema: gap b/w U1s
Rotations
- describe direction from side w/ largest contact point displacement
- i.e. MB, DP
Angulation: mesio-distal tip
Inclination: bucco-lingual
- lat. ceph
— U1s: 109d to maxillary plane
— L1s: 93d to mandibular plane
What inter-arch dental features are in ortho assessment?
Incisor relationship Overjet Overbite Centrelines Molar relationship Crossbites + Displacements
Discuss incisal relationship
1: incisal edge LIs occludes on cingulum plateau UIs
2: incisal edge LIs occludes post. cingulum plateau UIs
- 1: inc. overjet; UIs proclined or normal
- 2: retroclined
3: incisal edge LIs occludes ant. cingulum plateau UIs
Discuss overjet + overbite
Overjet: horizontal distance b/w incisal edge UIs + labial aspect LIs
- av.: 2-4mm
- Class 2/1: >
- Class 3: <
Overbite: vertical overlap of LIs by UIs
- av.: 2-4mm (1/3-1/2)
- complete: contact b/w teeth + teeth/palate
- incomplete: no contact
Discuss dental midlines
U midline (dental) coincident w/ facial midline U+L midlines coincident w/ each other L midline coincident w/ chin point
Discuss molar relationship
1: MB cusp U6 occludes in midbuccal groove L6
2: U6 occludes M
3: U6 occludes D
Discuss crossbites + displacements
Crossbites
- U teeth should occlude B to L; if occlude P = X-bite
- ant. or post.
- unilateral or bilateral
Displacement: mandibular deviation b/w centric relation + centric occlusion
Discuss growth control theories for bone, cartilage and soft tissue matrix
Bone
- no innate growth potential; no growth when transplanted
- growth @ sutures responds to outside stimuli; pulled apart
Cartilage
- nasomaxillary: some innate growth
- mandibular condyle: less growth when transplanted, considered growth site
Soft Tissue Matrix: bone + cartilage react to growth of soft tissue
- cranial vault: size of brain
- nasal + oral cavities: functional need
- mandible: impaired by TMJ ankylosis
Discuss theories of growth modulation
Genetic: homeobox control generic blueprint of growth
Epigenetic
- Functional Matrix Theory
— capsular matrix: indirectly by altering vol. of capsule
— periosteal matrix: directly on skeleton
- Updated functional Matrix Theory
General features of craniofacial growth
Follows somatic growth pattern
Rate inc. pre-/@ puberty
F earlier
Red. facial convexity (class 2); mandible frowns 18+
Continues throughout life
Discuss structures of cranial vault + growth
Comprises - flat bones — frontal — occipital — parietal — squamous part of temporal - sutures + fontanelles
Intramembranous ossification
- apposition: sutures + exterior
- resorption: interior
Structures of cranial base + growth
Comprises
- basioccipital
- ethmoid
- sphenoid
- petrous part of temporal
Endochondrial ossification
Spheno-occipital synchondrosis: affects AP
Surface remodelling
5 mechanisms of maxillary growth
Sutural Surface remodelling Displacement/Myofibroblasts Nasal Septum Functional Matrix
Discuss sutural growth of maxilla
Sutures
- frontomaxillary
- zygomaticomaxillary
- pterygomaxillary
- midline
- zygomatico-frontal (directly)
- zygomatico-temporal (indirectly)
Intramembranous ossification; apposition @ sutures grows forwards + downwards
Discuss displacement growth of maxilla
From 7-15y up to 1/3 forward movement due to passive displacement
Associated w/ sutural growth
Rotational component masked by periosteal remodelling
Discuss nasal septum growth
Cartilaginous growth
1 of 1ry mechanisms of nasomaxillary complex growth
- apposition @ sutures
- surface remodelling: down + forward, widening palatal vault
Considerably affects growth of U face
Discuss growth of mandible
Intramembranous Endochondral @ condyle - elongation - ant. + downward Surface remodelling (majority)
Discuss growth rotations of mandible
Determined by
- post. face height: condyles, synchondroses
- ant. face height: tooth eruption, soft tissue growth
Backward (clockwise)
- IO: red. overbite, ant. openbite
- EO: inc. FMPA + LAFH
Forward (anti-clockwise): class 2/2
- IO: inc, overbite
- EO: red. FMPA + LAFH
Discuss predicting of facial growth
Numerous methods
- 2ry sexual characteristics
- standing height
- age
- skeletal maturity
- dental age
No strong evidence for any of these; no real way to predict max. growth