Integrated Restorative Flashcards
endodontic lesion with periodontal involvement
inflammatory lesion originating in the pulp however, it will manifest in the periodontium; this lesion may mimic periodontitis
if incorrect diagnosis & perio therapy undertaken with curette this will destroy PDL & compromise prognosis of tooth
periodontal lesion with endodontic involvement
inflammatory lesion in the marginal periodontium but manifests in the pulp
if plaque only colonises the external root surface there is limited effect on a normal healthy pulp
pulp necrosis may occur when the periodontal process extends to apical foramen; prognosis here is poor
true combined lesion
both an endodontic lesion & periodontal lesion occurring simultaneously & independently
tx of perio-endo associated teeth
e.g. ptx has periodontal abscess on 1 tooth yet extensive pocketing & bone loss it is likely to be arising from perio disease so tx should be sub gingival debridement
or if pocketing is isolated to 1 tooth the tooth should be endodontically treated
if uncertain but tooth is non vital the endo tx tooth & observe response
5 properties of occlusal forces to be taken into consideration
- magnitude
- velocity
- frequency
- duration
- direction
what are the ideal occlusal contacts in the ICP
posterior = lower buccal cusps should occlude against marginal ridges and fossae of opposing teeth
anterior = lower incisal edges & canine tips will occlude against cingulum
what is the ICP
intercuspal position - the position of the jaws when the maxillary and mandibular teeth are in maximum intercuspation
what is canine guidance
in canine guided occlusion, the overlap of maxillary and mandibular canines results in disengagement of maxillary and mandibular posterior teeth during excursive movement of mandible i.e. in excursions one or more anterior teeth contact & there is immediate discursion of teeth on the non working side
what is group function
multiple contact relations between the maxillary and mandibular teeth in lateral movements on the working side i.e. the simultaneous contact of numerous teeth acts as a group to distribute occlusal forces on the working side & there is disclusion of teeth on the non working side
TMJ movement
TMJ will move differently depending on which side the jaw is moving to laterally - side jaw is moving towards is called the working side - this condyle will rotate & the non working side will be the side in which the mandible moves away from - this condyle will translate downwards, forwards & inwards i.e. it will orbit
name the 3 forms of tooth guidance
- canine guidance
- group function
- balanced articulation - complete dentures only
normal function
most tooth contact in chewing & swallowing will occur in maximum intercuspation
parafunction
purposeless clenching & grinding which causes greater & longer forces than the teeth are put under during normal function that can cause damage to teeth, periodontium, muscles, joints
what is posselt’s envelope
refers to range of motion of mandible
what is RCP
Retruded contact position (RCP) also known as centric relation, describes the relationship of the mandible to maxilla when the mandibular condyles are in their most superior and anterior position in the articular fossa, independent of tooth contact - this is an easily reproduceable position
rotational movement according to posselts envelope
In the TMJ, the initial mouth opening occur by rotation, within the inferior cavity of the joint
the TMJ rotates around a fixed axis within the condyle, with no antero-inferior translation
the maximum jaw opening with this rotation movement is indicated as ‘R’ on the Posselt’s envelope of motion
translation according to posselts envelope
when the jaw is opened wide, it exceeds the maximum range of jaw opening with rotational movement, and a secondary gliding movement occurs i.e. translation which occurs within the superior cavity of the joint
During translation, the condylar heads slide anterior and inferiorly down the articular eminence, allowing the jaw to open wider. This path of movement is the line produced between ‘R’ and ‘T’, where ‘T’ indicates the maximal jaw opening with full translational movement
edge to edge in posselts envelope
Edge-to-edge articulation is when opposing front teeth meet along their incisal edges when teeth are in maximal intercuspal position - this is in ICP
maximum protrusion in posselts envelope
When the lower jaw is pushed anteriorly as far as possible with some teeth in contact, it is said to be maximum protrusion
mounting casts in an articulator
upper = this requires a facebow - this will transfer the relationship between the maxillary teeth & axis of rotation from the patient to the articulator
it will position the upper cast vertically & the angulation of the occlusal plane in relation to a horizontal reference plane
lower = mounted in ICP or RCP
registering the occlusion
if ICP used and the 2 casts fit together obviously then no registration medium is needed
if no obvious ICP then a registration medium is required & it must not alter vertical dimension & must allow natural occlusal stops
when not using ICP how to mount casts
to take this occlusion (RCP) the mandible must be manipulated so there is no muscle resistance & push the mandible back to register
as there is to be a new IP a registration is always required
it should be as thin as possible without allowing occlusal contact as occlusal contact will malform the retruded arc
process of restoring worn anteriors
- impressions taken
- diagnostic wax up on casts
- acrylic mould of wax up
- filled with temporary material and attached to teeth
- impressions taken again
- custom anterior guidance table produced from impressions
- crowns produced to new guidance
2 forms of horizontal force placed on teeth
- constant - only in orthodontic appliances
- intermittent - forces the teeth are put under all the time
in a healthy periodontium with abnormal occlusal forces
there will be no gingival inflammation and no change in attachment this is because periodontitis is a plaque related disease
in healthy periodontium with excessive abnormal occlusal forces
if the load is too great it becomes pathological; this is where the load will be too great for the adaptive capacity of the PDL leading to continued increase in PDL width
occlusal trauma
tooth mobility which is progressively increasing and / or mobility associated with symptoms - there must be radiographic evidence of increased PDL width (think of wiggling post in the ground)
occlusal forces & periodontitis
there will only be vertical bone loss due to the 2mm radius of destruction around plaque
there may be increased rate of disease
progression with both acting together & there may be greater levels of attachment loss at the overlapping
areas of the plaque induced inflammation and trauma
induced inflammation. However alone occlusal forces will not exacerbate gingival inflammation
4 factors determining tooth mobility
- width of PDL
- height of PDL
- inflammation
- number, shape & length of roots
what can improve perio related tooth mobility & why
if plaque adequately removed from teeth then there may be healing of periodontal tissues which will increase tissue tone due to increased collagen fibres thus producing a long junctional epithelium which can improve mobility
3 causes of tooth migration
- loss of periodontal attachment
- unfavourable occlusal forces
- unfavourable soft tissue profile
deep traumatic overbite
upper incisors stripping lower gingivae - trauma relieved using occlusal splint & ortho management, occlusal stops for anterior teeth may also be needed, any plaque related inflammation must also be treated
why must perio be arrested before restorative procedures
if inflamed gingival margin it is likely to bleed during operative procedures & its apico-coronal location is unstable so there may be moisture contamination & could be exposure of a restorative margin
issues with subgingival margins
associated with loss of attachment 1-3yrs after placement leading to pocketing & recession
what is the biologic width
used to determine where restoration margins should be placed. usually around 2mm - made up of 1mm of CT from alveolus to the junctional epithelium and 1mm junctional epithelium i.e. from the alveolus & depth of gingival sulcus
what happens if restoration margins encroach biologic width
this will lead to persistent inflammation and loss of attachment - remember that biologic width is at different heights around the tooth
restorative considerations in perio
crowns & bridges can cause plaque retention, pulpal damage & unfavourable transmission of occlusal forces
RPDs can provide direct trauma from components to teeth & periodontal tissues
so from a perio perspective, fixed prostheses are preferable as long as there is enough support
what is ante’s law
the combined periodontal area of the abutment teeth should be equal to or greater than the periodontal area of the tooth or teeth to be replaced
when to place crowns (4)
- tooth fracture
- restoration failure
- 2ndary caries
- endo
when to replace crowns (4)
- failure aesthetically
- 2ndary caries
- poor marginal adaptation causing periodontal disease
- lost crown
types of full gold crown
Type I & II - small & large inlays
Type III & IV - crowns, bridges, RPDs
pros & cons to full gold crowns
pros - high strength in x section so needs minimal reduction in tooth tissue, similar hardness to enamel
cons - cost & aesthetics
+/- of traditional feldspathic porcelain as crown
pros - similar translucency & shades to natural teeth, biocompatible, can be etched for bonding to tooth
cons - margin often poor due to shrinking when fired, abrasive to opposing teeth, brittle, unreliable for bruxists / posterior teeth
+/- pressable ceramics as crowns
can be used as single unit anteriors / posteriors or as small span anterior / premolar bridges
high aesthetic but if heavy occlusal loads this can cause crown to break
+/- procera milled crown
this is a densely sintered (high levels of powder) non porous aluminium oxide
single unit
as it can be milled it can be produced quickly with good aesthetics & strength
shouldn’t be used in heavy occlusal loads
zicronium oxide core ceramics as crowns
milled using CAD/CAM machines so very quick
dense strong opaque core but only limited shades
not etchable so must be cemented
can be useful for limited fixed PDs
how much tooth tissue to be cut with crowns other than gold & metal ceramic
2-2.5mm must be cut into tooth tissue
MCC +/-
+ good strength & aesthetics
- large amounts of tooth tissue need cut, too strong & can cause root #, poor appearance in comparison to pure ceramic crowns due to uniform colour throughout tooth & at cervical margin, can cause allergy abrasive to opposing teeth
porcelain fused to non precious metal crown
produced of fluorapatite leucite glass ceramic with Ni Cr & Mo as a base (or CoCr)
single crowns / small to large span bridges
good aesthetics
potential hypersensitivity
porcelain fused to titanium crown
silicone dioxide & aluminium oxide with a core of pure grade 2 titanium
option for single crowns & small span bridges
shouldn’t be used in resin retained bridges, long span bridges or minimal occlusal clearance
biocompatible
crown prep for metal crowns
thickness >0.5mm
non functional cusps >1mm
functional cusps >1.5mm
chamfer, should or shoulder with bevel margins should be used
crown prep for ceramic crowns
thickness = 2mm
functional cusps = 2.5mm
incisally = 1.5-2mm
shoulder or heavy chamfer margin
crown prep for MCC
functional cusps = 2.5mm
non functional cusps = 2mm
incisally = 2mm
shoulder or heavy chamfer of 1.2mm
cementation of crown
RMGI - metal or MCC crowns
resin - porcelain veneers, ceramic onlays, resin bonded crowns
must be good moisture control with dam, area should be cleaned with chlorhexidine, seat with firm finger pressure then ptx bite, excess should be removed and margins checked with probe
list most to least common causes of crown failure (6)
- caries
- perio
- fracture of abutment tooth
- endo
- fracture of porcelain
- loss of retention
if endo treated tooth has no cuspal coverage it is 6x more likely to fail
indications of veneers & when to use
indications - more conservative than crowning teeth, retentive, durable, great aesthetics, preserve pulp & gingivae, allow for RCT later if necessary, only use if less than half the crown is missing
when - erosion, discolouration, bridge repair, spacing, crowding, chips/fractures, OVD increase, diastema
contraindications of veneers
destructive, removes healthy tooth tissue, bruxism, poor OH, nail biting, excessive tooth loss, crossbite
4 prep stages for a veneer
- incisal prep
- buccal prep
- interproximal extension
- gingival margin
buccal prep of veneer
must be in 3 planes as there are multiple curves to buccal aspect of tooth:
cervically 0.3mm (thinnest enamel here)
mid buccally 0.5mm
incisally 0.7mm
interproximal extension of veneer
if through contact point there may be some drift, it can also be hard to clean excess cement
gingival reduction of veneer
gingival margin must be placed around 0.5mm into gingival sulcus for aesthetics but must not be any deeper as if it is then it will interfere with biologic width so margin must be in sulcus itself. also emergence profile of the veneer itself must be the same as that of the tooth originally
incisal reduction of veneer (4)
- feathered margin - no incisal overlap, margins will be at incisal edge, likely to have breakage / microleakage
- window prep - most protected via window of enamel, can be minimal & localised but poor aesthetics as margins visible
- incisal bevel - good but may be some breakage at incisal edge
- incisal overlap - 2mm reduction for translucency & strength but lots of tooth tissue removed & thin area on cast may break
problems with veneers
- if only 1 single tooth veneered there may be difference in appearance of this tooth
- may discolour & may look unnatural if just a single colour
- occlusion problems if crossbite / bruxism
- if debonding there may be staining or caries
- marginal staining
- over prep can lead to sensitivity or loss of pulp vitality
- fracture due to poor internal fit or excess seating pressure
inlays v onlays
inlay = indirect intracoronal restoration; within body of tooth but no cuspal coverage
onlay = indirect extra coronal restoration; covers body & cusps
pros & cons of gold inlay / onlay
Type I / II
+ high strength, casts accurately, high polish so will prevent plaque accumulation to itself & suitable for bruxists
- unnatural appearance, may not retain well, must be cemented in place not bonded
pros & cons of composite inlay / onlay
+ good aesthetics, when used indirectly very strong, repairable, less polymerisation shrinkage so less microleakage & pain
- not as strong as gold, pooling of bonding materials leading to poor bonding
cermoer as inlay / onlay
+ aesthetic, more durable than composite, increased fracture toughness & wear resistance, repairable e.g. Belleglass
ceramic as inlay / onlay
+ aesthetic, wear resistant, better bond strength than composite (good for poor retentive cavities), can transmit forces to teeth more, less marginal leakage
- all margins must be placed on enamel, wear resistance could be bad, low fracture resistance
inlay / onlay prep
- no undercuts present (any should be blocked out)
- walls must be diverging at 4-6 degrees
- margins must be chamfered & no margins should be through occlusal contacts; must be completely clear of contact with opposing tooth
- occlusal reduction = 2mm (1mm for gold)
- tooth must be provisionalised before impression; not in GI / eugenol
- must have adequate bulk & adequate remaining tooth tissue
indications of inlay / onlay (4)
- extensively restored teeth
- repeated fracture of direct restoration
- difficulty obtaining occlusion
- protection of remaining tooth tissue
adv of inlay / onlay
aesthetic
conservative
strong
cuspal protection
less polymerisation shrinkage, microleakage, pain, cuspal fracture
disadv of inlay / onlay
ceramic wearing opposing teeth
ceramic may fracture at try in due to lack of bulk
debonding due to poor etch or occlusion
marginal ditching
expensive
clinical & lab reasons why a try in fails
clinical : incomplete temporary removal / gingival tissue encroachment due to poor temporary / distortion of impression
lab : interproximal over extension / marginal over extension / resin restoration expansion / blebs on fitting surface
where are dahl appliances placed and why
often placed palatally on upper anteriors, usually from canine to canine
provide inter occlusal space anteriorly making an open bite to allow for restoration of anterior teeth following posterior over eruption
types of dahl
direct composite made using vacuum formed stent or indirect CoCr/composite/compomer
dahl construction
requires elastomeric impression of 13-23 with facebow & interocclusal record, lab will mount casts on semi adjustable articulator and it will be waxed up however there may not be enough space to build up original height. good diagnostic tool for parafunction.
outcome of dahl
when OVD is increased to create space this will eliminate occlusal reduction in the crown production
if OVD not increased there is need for occlusal reduction which can result in loss of vitality & short non aesthetic crowns
cervical abfraction
non carious tooth surface loss causing wedge shaped lesions at the cemento-enamel junction
2 phases of root resorption
- injury to non mineralised tissues e.g. pre-dentine / pre-cementum
- stimulation (to keep inflammation present)
5 main types of root resorption
- internal resorption
- external resorption
- ortho induced root resorption
- tumour
- replacement resorption
internal root resorption
initiated within pulp chamber / root canal of tooth primarily caused by chronic pulpal inflammation
histologically - loss of predentine
often asymptomatic but when it progresses; periradicular abscess formation & tooth mobility
can be seen in cervical region as pink tooth
radiographically - uniform round / oval radiolucent enlargement of canal
tx = if non perforated then pulpectomy with non setting CaOH for 4-6wks then obturate canals with GP // if perforated then use MTA
external root resorption
initiated in periodontium & maintained by necrotic pulp pulpal tissue
radiographically - moth eaten appearance on outer surface
in pathological root resorption due to perio infection there is injury to precementum apical to epithelial attachment followed by bacterial stimuli from PDL sulcus; radiographically this is seen as a single resorption lacuna in the dentine at crestal bone level expanding coronally & apically
pathologic external root resorption
usually from impacted tooth or pressure from tumour
replacement root resorption
usually in trauma i.e. intrusion / avulsion where healing in cementum isn’t possible & bone comes into contact with root surface without an intermediate attachment apparatus
clinically - lack of physiologic mobility, percussion sound = metallic, if process continues tooth may be infraoccluded
radiographically - resorption lacunae are filled with bone & PDL space is missing, no radiolucencies
aka ankylotic root resorption
