2 - malocclusions and oral anatomy
definitions
occlusion
position of teeth when jaws are closed
normal occlusion
“Perfect” interdigitation of the upper and lower teeth when jaws are closed
Maxillary incisors are cranial to mandibular incisors
mandibular canine teeth incline buccally and rest in the interdental space between maxillary 3rd incisor and canine tooth
maxillary premolar teeth do not contact mandibular premolars → scissor bite
maxillary premolars are buccal to mandibular premolars
summary
upper teeth always sit on the outside of the mandibular teeth
premolars do not touch each other
mandibular canines tilt so that tip is pointed out and sits between incisors and canine tooth
malocclusion
any deviation from a normal occlusion
dental malocclusion
abnormal position of a tooth or teeth
Class 1 malocclusion
skeletal malocclusion
symmetrical or asymmetrical deviation of bones that support the dentition
class II-IV malocclusions
causes
hereditary - orofacial skeletal length variations → brachycephalics
systemic influences - congenital or developmental
local influences - persistent deciduous teeth, trauma, oral cyst/masses, behavioral habits
dental malocclusion
malocclusion Class 1
normal rostrocaudal relationship of dental arches
normal jaw length
malposition of one or more teeth
terms
distoversion - tooth angled in distal direction
mesioversion - tooth angled in mesial direction
buccoversion - tooth angled in a buccal direction
linguoversion - mandibular tooth angled in lingual direction
palatovesion - maxillary tooth angled in a palatal direction
labioversion - tooth angled in a labial direction
distally displaced
mesially displaced
buccally displaced
lingually displaced
palatally displaced
labially displaced
crossbite
summary: lower teeth are pointed out when they should be pointed in
cross bite - mandibular teeth more buccal or labial than opposing maxillary teeth
anterior crossbite - mandibular incisors are labial to maxillary incisors - similar to underbite but jaw length is normal
caudal crossbite - mandibular cheek teeth are buccal to maxillary cheek teeth
can be seen in other classes of malocclusion
symmetrical skeletal malocclusion
malocclusion class II - mandibular distoclusion - overbite
abnormal rostrocaudal relationship between dental arches
mandibular arch occludes caudal to its normal position - mandibular bone too short
canines and incisors can cause traumatic injury to palate
malocclusion Class III - mandibular mesioclusion - underbite
abnormal rostrocaudal relationship between dental arches
mandibular arch occludes rostral to its normal position
canines and incisors can cause atrition to lower incisors
asymmetrical skeletal malocclusion
malocclusion Class IV - Wry bite
skeletal malocclusions that can occur in rostrocaudal, side-to-side, or dorsoventral directions
treatment options for malocclusions
extraction
ball therapy -
needs to be a space for mandibular canine teeth to move into
works for mandibular canine teeth
mild linguoversion
does not work for lingually displaced teeth
permanent dentition ONLY
15 min TID
orthodontic appliances
crown reductions and vital pulp therapy
odontoplasty or “blunting” of teeth
oral anatomy
mouth
entrance to oral cavity
oral cavity
lips to oropharynx - level of tonsils
vestibule
theoretical space between lips/cheek and teeth/gums
includes upper/lower lips/commisure, lower lip frenulum x 2, upper lip frenulum x 1, philtrum, buccal mucosa/cheeks
lower lip frenulum - where lips attach to bone between canine and first premolar
upper lip frenulum - where lips attach to bone between incisors
oral cavity proper
from alveolar ridges and teeth to oropharynx
area between roof and floor of mouth → filled by tongue
hard palate
separates cranial oral cavity from nasal passage
composed of incisive papilla, median raphe, rugae
soft tissue covering bony vault of oral cavity proper
rugae
transverse epithelial ridges
should be symmetrical on either side of median raphe
no rugae = immune mediated disease
cleft palate - incomplete transposition of hard palate, communication between nasal passage and oral cavity
soft palate
separates caudal oral cavity from nasal passage
soft tissue unsupported by palatine bone
can make contact with oral surface of epiglottis when relaxed
tongue
body - starts at frenulum
tip
root - where tongue attaches to oropharynx
margin
floor of mouth
salivary ducts
parotid - maxillary P4
zygomatic - Maxillary M1/2
mandibular and sublingual come out of the same duct at tongue frenulum
molar gland - cats only
clefts
cleft lip = primary cleft palate
cleft of lips ± incisive bone of palate (cranial to canines)
cleft palate = secondary cleft palate
cleft of palate caudal to incisive bone and soft palate
cleft of soft palate only
oral mucous membranes
specialized mucosa
dorsum of tongue
lingual mucosa
thick/rough cornified mucous membrane
masticatory mucosa
hard palate, gingiva
undergoes routine masticatory trauma and stress
general/lining mucosa
remaining oral mucosa
buccal, mucobuccal, mucolabial folds
mucosa that is attached to alveolar bone - attachment is loose and movable
gingiva
free (marginal) gingiva
distal-most portion of gingiva
needs to be cleaned under during dental
attached gingiva
relatively immobile
attached to alveolar bone via periosteum
width is vital for planning periodontal treatment
vital to tooth survival - must maintain collar of attached gingiva for remaining neighboring teeth of extracted teeth
interdental papilla
peak of gingiva between teeth
maintains gingival health by preventing food and debris getting caught between teeth
mucogingival junction
demarcation between attached gingiva and alveolar mucosa
used for mucogingival flap
oropharynx
from isthmus fauces to base of epiglottis
isthmus fauces
orifice between oral cavity and oral part of pharynx
bounded by
palatoglossal arches
tongue
soft palate
tonsils
located in back of pharynx
often not visible when in crypts
common location for grass awns