Biomechanics and tissue changes in edentulous patients Flashcards
What is biomechanics?
study the mechanical nature of biological processes
the study of the action of eternal and internal forces on the living systems - mastication
help in designing new denture
Effect of tooth loss on the PDL?
viscoelasticity of the PL missing
sensory feedback mechanism
osteogenetic potential that responds to the forces applied missing
support and sensory perception are therefore altered with complete dentures
mucous membrane sever the functions of PL with its attendant deficiencies
Role of the PDL?
support and positional adjustments of the tooth
also sensory perception
What usually happens with tooth loss on the alveolar bone?
resorption of the alveolar bone - reduction of the residual ridge
How many Classifications of alveolar bone resorption?
1-6
When does the most amount of bone loss occur in after tooth loss?
first year
class 1 alveolar bone resorption?
dentate
class 2 bone resorption?
post extractionc
class 3 bone resorption?
rounded ridge, adequate height and width
class 4 bone resorption?
knife edge ridge, adequate height, inadequate width
class 5 bone resorption?
flat ridge, inadequate height and width
class 6 bone resorption?
depressed ridge with varying degrees of basal bone loss that may be extensive but follows no predictable pattern
3 dimensional changes in alveolar bone loss?
interach changes:
ateroposteriorly: shorter
transversely: maxillary arch narrowed and mandibular arch broader
vertically: interach distance increases
What counteracts the increase in interarch increasing in dimension?
vertical shortening of lower face - cased by closing moving or autorotation of mandible
more pronounced chin and problematic jaw
Effect of tooth loss on muscles?
as alveolar bone loss increases, the circumolar and FOM muscles become increasing superficial
decrease in masticatory forces achieved with complete dentures
what muscles doe tooth loss affect?
circumolar and FOM muscles
why does masticatory force decrease due to tooth loss?
changes pt diet
could have a systemic effect e.g. vitamin intake due to less meat or fibrous vegetables
Effects if edentulous state, changes manifesting n edentulous pts? (17)
altered facial appearance due to chnaging maxillo-mandibular relationship
altered an dreduced support system
compromised tolerance of the oral tissues
increased risk of pathological changes
increased risk of maladaptive denture wearing experience
reduced support area
reduced or altered neuromuscular control
reduced chewing forces
reduced salivary flow
reduced healing potential;
resulting in compromised denture bearing tissues
phycological
emotional
aesthetic: lower height, collapse of the commissure, cheeks, lips
functional: mastication speech
systemic - metabolic, cardiovascular, cancer
local tissue changes
What is movement of the denture related to?
stability of the denture
resiliency of the mucosa
- movements can further complicate the reduced support status
How does the movement of the complete denture manifest?
displacement
lifting
sliding
tilting
rotating of the dentures
muscles affecting retention and stability?
orbicularis oris
buccinator
risorius
intrinsic and extrinsic muscles of tongue
Dentures are constructed with the following objectives?
minimise the forces transmitted to the supporting tissue
reduce the movement of the dentures
Factors under the control of the clinician?
appropriate optimal extension of the denture base
maximum intimate contact of the denture base with the basal seat
designing the smooth surfaces of the denture to utilise and balance peri-oral and tongue muscles activity to maximise retention an stability
arrangement of the prosthetic teeth in the neutral zone
