optech Flashcards
3 extrinsic causes of staining
smoking
tannins - tea coffee
Chlorhexidine
intrinsic causes of staining
fluorosis
tetracycline
physiological - ageing
what is the first method of whitening for extrinsic staining
HPT
2 types of bleaching
internal non-vital bleaching
external vital bleaching
how does vital external bleaching work
active agent is H2O2
bleaching oxidises chromogenic products within the tooth substance
leads to smaller non pigmented molecules
ionic exchange in metallic molecules leading to lighter colour
what does H2O2 break down to form
water and oxygen
what is the active oxidising agent in H2O2
HO2 free radical
3 constituents of bleaching gel
carbide peroxide - active agent
carbopol - thickening agent
urea - raises pH
what does carbamide peroxide break down to form
hydrogen peroxide and urea
tooth desensitising agents used in bleaching gel
potassium nitrate
calcium phosphate
fluoride
4 factors affecting bleaching
concentration of solution
temperature
cleanliness of tooth
time
why is it important to ensure there are no margins om restorations before bleaching
leakage damages pulp
warnings for patient before bleaching
sensitivity
relapse
allergy
might not work
2 types of vital external bleaching
chair side
home
why is there a good initial result to teeth whitening
dehydration
maximum concentration of H2O2 legal
6 %
equates to 16.7% carbide peroxide
2 features of whitening splint
stops 1mm short of gingival margin
buccal spacer for gel placement
when should you consider bleaching
age related discolouration
mild fluorosis
post smoking cessation
predisposing indications that pt will be sensitive after whitening
pre existing sensitivity
high concentration of bleaching agent
gingival recession
issue with bleaching teeth with composite fillings
teeth bleach composite does not
need to change filling then upkeep bleaching
why should you delay restorative procedures a day ideally a week after bleaching
oxygen remains in the enamel structure and causes problems with bonding
what should never be used to whiten teeth
chlorine dioxide
pH3 - softens teeth - sensitivity
indications for internal non-vital bleaching
non-vital tooth
adequate RCT
contraindications of internal bleaching
staining by amalgam
heavily restored tooth
risk of internal non-vital bleaching and how does it occur
external cervical resorption
diffusion of H2O2 through dentine into periodontal tissues
caused by too high concentration and heat
technique for internal bleaching
remove dark dentine
etch internal tooth surface with phosphoric acid
10% carbide peroxide in cavity
place cotton wool
seal with GIC
repeat weekly
restore palatal cavity when desired shade obtained
when would you use microabrasion - 3
por=st porto demineralisation
fluorosis
demineralisation with staining
what is micro abrasion
combination of erosion and abrasion - acid 18%HCl and pumice
removes discolouration limited to outer layers of enamel
3 medico legal issues of whitening
excess of 6% - fitness to practice
non-registrants of gdc - prosecuted under dentist act for illegal practice
non dentists supplying bleach >6% - trading standards
when can you use excess of 6% h2o2
prevention of disease
2 medical contraindications of whitening
glucose 6 phosphate dehydrogenase deficiency
acatalesemia
what should you do after micro abrasion to reharden the surface
apply fluoride varnish
consequence of too much micro abrasion
yellowing as dentine shows through
sensitivity permanently
function of supra hyoid muscles
elevate hyoid bone and depress mandible
function of MOM
depress elevate and lateral movements of mandible
2 major movements of mandible
rotation
translation
during the small rotational hinge movement from OVD to RVD, what axis do the condyles rotate around until the terminal hinge axis
horizontal
what is the face bow used to relate
maxilla to terminal hinge axis of rotation
what muscle contracts during translation of the condyle
lateral pterygoid
condyle movement during translation
down and forward
wear is posselts envelope
represents extremes of mandibular movement
border movements of the mandible in sagittal plane
ICP another name
centric occlusion
maximum interdigitation of the teeth
position of the condyle in maximum opening
full translation of condyle over articular eminence
position of condyle in Retruded axis position
most superior anterior position of condyler head in fossa
what is RCP
first tooth contact when mandible in in retruded axis position
what is the Bennet movement
lateral translation of the mandible
what is the Bennet angle
the path of the non working condyle in the horizontal plane during lateral excursion
origin insertion and function of Temporalis
temporal fossa
coronoid process
elevates and retracts mandible
lateral pterygoid origin insertion and function
superior head - greater wing of sphenoid
inferior head - lateral border of lateral pterygoid plate of sphenoid
inserts neck of mandible
SLP positions disc on closing
ILP protrudes and depresses mandible and causes lateral movement
medial pterygoid origin insertion and function
superficial maxillary tuberosity
deep head medial aspect of lateral pterygoid plate
ramus of mandible - elevates mandible, lateral movement
masseter origin insertion and function
maxillary process of zygomatic bone and zygomatic arch
ramps of mandible
elevates mandible
when to mark tooth contacts
before preparing a tooth or removing a restoration
after placing a crown or restoration
what is fremitus
palpable or visible movement of tooth when subject to occlusal forces
what are functional cusps
cusps that occlude with opposing teeth in intercuspal position
palatal cusps of uppers
buccal cusps of lowers
what are non function cusps
cusps that do not occlude with opposing teeth in intercuspal position
palatal cusps of lowers
buccal cusps of uppers
what is overjet
relationship between the upper and lower incisors in horizontal plane
normal overbite
2-4mm
2 ways of examining occlusion
static
dynamic
describe canine guidance
mandible moves working side
only canines contact
no posterior tooth contacts
describe group function
mandible moves to working side and multiple teeth contact on working side
what teeth occlude in protrusion
only incisors +/- canines
3 types of occlusal interference
working side
non-working side
protrusive
what is protrusive interference
any posterior contact during protrusion
eccentric bruxism
grinding teeth
centric bruxism
clenching teeth
signs and symptoms of bruxism
tooth wear
fractured restorations
muscle pain and fatigue
pain and stiffness in TMJ
define occlusal trauma
injury resulting in changes to PDL and supporting tissues as a result of occlusal forces
primary occlusal trauma vs secondary occlusal trauma
primary is intact periodontium
secondary is reduced periodontium
Bennet angle and condylar guidance angle on average value articulator
15 bennet
CGA 30
what is a conformative approach to recording occlusion
ICP reg without changing OVD
provision of restorations in harmony with the existing jaw relationship
techniques to record RCP
chin point guidance
bimanual manipulation
a mutually protected occlusion has what guidance
canine guidance
3 predictors of trauma outcome
timing of treatment
root development
severity of injury
potential long term complications of trauma
discolouration
loss of vitality
inflammatory root resorption
unfavourable tooth position
what does yellow tooth indicate
pulp canal obliteration
what does pink tooth indicate
rupture of blood vessels during severe trauma - haemorrhage in pulp chamber
how long after trauma will you see radiographic signs of pulpal necrosis
3-4 weeks
treatment options for pulpal necrosis
primary endo
internal bleaching
extraction and prosthetic replacement
3 types of inflammatory root resorption
internal
external
replacement
trauma prior to prepubescent growth spurt has the highest risk of ankylosis - why?
continues alveolar growth
