Complex direct restorations Flashcards
complex posterior direct restorations
used to replace any missing structure of teeth that have fractured, have extensive caries or have existing restorative material
usually replace on or more missing cusps
incidence of tooth fracture
molars are frequently presented fractures than premolars
buccal cusp of maxillary molars
lingual cusp of mandibular molars
most fractured teeth had been restored on three or more surfaces
Treatment plan options
Indirect restoration - onlay/crown - teeth with crowns are less likely to recieve extensive treatment (over a 10 yr period) than are teeth with large amalgam restorations - treatment of choice
DIrect restoration - complex direc restoration - less expensive, transitional restoration
Indications for Complex direct restorations
definitive final restorations - patient financial concerns
transitional restorations - pending final treatment plan, questionable pulpal or periodontal prognosis, management of caries
Indications for complex amalgam restorations
molars
lack of cervical enamel
high caries risk/poor oral hygiene
financial concerns
no esthetic requirements
no amalgam phobia
patient requires a short appointment
reduction of weakened cusps
fracture strength increases when cusps are covered (removed or reduced)
Rules for Cusp removal
if unsupported tooth structure OR caries extension from primary groove to cusp tip (up the cusp incline) is:
1/2 the distance: NO removal is indicated
1/2 to 2/3 the distance: consider cusp removal
over 2/3 the distance: remove the cusp
Cusp Reduction
Remember amalgam needs 2.0 mm for sufficient bulk - for resistance to fracture
reduce cusps to give enough space - 2.0 mm
pulp protection
direct pulp cap - small exposure, previously asymptomatic
indirect pulp cap - less than .5 mm remaining dentin thickness
thermal protection - mostly under amalgam restorations
goal of pulp capping procedures
maintain a healthy pulp
stimulate dentin bridge formation
conditions necessary for a successful pulp cap
pulp is vital
asymptomatic pre operatively
small exposure
isolated - not contaminated with saliva
no excessive hemorrhage
the restoration is well
materials for pulp protection
MTA
calcium hydroxide
calcium silicate
glass ionomer
MTA
mineratl trioxide aggregate - same compounds as Portland cement (calcium oxide, aluminum oxide, silicone dioxide)
“bioactive” and “dentinogenic” - used in direct pulp capping procedures
advantage: reparative dentinogenesis was observed earlier than with calcium hydroxide
cover with GI or RMGI
expensive
calcium hydroxide
gold standard - direct and indirect pulp capping
placed on the exposure or pink dentin
placed only on axial or pulpal floor
soluble - must not extend to margins, wash out of material will result in open margins
low compressive strength - should be covered with GI or RMGI
calcium silicate
tricalcium silicate in a hydrophyllic monomer
stimulates hydroxy apatite and secondary dentin bridge formation
direct and indirect pulp cap
light cured
increments of no more than 1.0mm
liner not required over Theracal
Glass Ionomer/Resin Modified Glass Ionomer
Liner not a pulp therapy material
should not be used directly over the pulp or if the RDT is <.5mm
used over pulp capping materials
auto cure or light cure
can be used in a sandwich technique
fluoride release
Comparison of Pulp Capping Materials
What do we use for pulp therapy
direct or indirect pulp cap
calcium hydroxide directly over the exposure or pink dentin (<.5mm RDT)
theracal can be used instead of calcium hydroxide
axial wall or pulpal floor only
thin layer
atleast 1.0 mm from cavosurface margins
should not compromise retentive features of the preparation GI or RMGI over the calcium hydroxide. GI/RMGI not neessary over Theracal
currently under review at the dental institute
Liners
GI or RMGI should not be placed in contact with the pulp
GI or RMGI - closed sandwich (restorative material is present at all cavosurface margins, open (Gi/RMGI is exposed at cervical margins
sandwich technique is used for composite restorations
GI or RMGI can be used under amalgam restorations as a liner for thermal protection
Final Tooth Preparation
Retentive features
opposing vertical walls
coves and locks
pins
amalgam pins
opposing walls
slightly convergent
What if there are no opposing walls?
try to create proximal boxes which have converging walls
hard stained dentin - no need to remove
Slots, Coves and Locks
Slots & Coves are horizontal
Locks are vertical
Slots remove more tooth structure than pin placement
Slots do not create internal stresses in dentin
slots, coves and locks are placed in dentin, not at the DEJ
330 bur
Pins
Self threading pins come in a variety of sizes (diameters)
slightly larger than the drill
placed w/a slow spped handpiece
self threading and self shearing
placed in dentin - 2.0 mm into dentin, 1.5 - 2.0mm extends out of the dentin into the prep
2.0 mm space for the amalgam occlusal to the pin
one pin per missing line angle
3-5 mm between pins
pin hole/ pin is placed parallel to the external surface of the tooth (to avoid perferation out of the tooth)
Pins Cont’d
provide retention only - do not strengthen the amalgam
problems:
perforation into the pulp or periodontium
stresses generated in dentin
broken/loose pins
2.0mm amalgam above the pin, 2.0mm pin extending above the floor of the prep, 2.0 mm of pin into dentin, pins are parallel to the external surface of the tooth
Pins Cont’d AGAIN
green areas are the preferred areas for pin and other retentive features
white areas are to be avoided bc of furcations, concavities or thin dentin
grey areas can have retentive features placed with caution
Amalgam Pins
used when there is insufficient room to place self threading pins
can be prepared w/a 330 bur
- 0mm in diameter
- 0mm in depth
used mostly when there are few or no vertical walls
mechanical retention forms (slots, amalgam pins and grooves) are less likely to create stress in dentin, microfractures or penetrate into the pulp than threaded pins
Amalgam bonding
etch enamel and dentin, rinse, leave moist
apply multiple coats of primer, dry
mix catalyst and base of a self cure or dual care resin cement or unfilled resin base and catalyst
apply to dentin and condense amalgam immediately
amalgam mixes with the resin cement
amalgam bonding retention
no diff between the performance of pin retained amalgam and bonded amalgam restorations
amalgam bonding agents were equal to four pins or four amalgam pins
amalgam bonding resistance
amalgam bonding has little effect on frature resistance of teeth
no evidence to either clain or refute a differnce in survival between bonded and non bonded amalgam restorations
Remember
Amalgam must be 2mm in thickness to resist fracture
final amalgam must have 2mm of thickness over cusps
all condensation must be completed before the amalgam beings to set - can not add amalgam to set amalgam
Modification Request
What - this is what you want to do - this is a VERB - extend, deepen, prepare
where - use proper terminology
why - usually to remove caries or unsupported tooth structure
how much - estimate
placement of pulp protection
mix a small amt of calcium hydroxide (Dycal)
apply the Dycal w/ the small ball burnisher to the area showing the pulp exposure or pink dentin
placed in the deepest area of the pulpal or axial wall only
clean any excess from the margins, floor or axial wall w/ a spoon excavator so the calcium hydroxide is only in the area that would be pink dentin or the pulp exposure
never at cavosurface, should not remain on the axio pulpal line angle, not used on the entire pulpal floor, must be covered w/ GI or RMGI
Ketac Bond
shake the bottle to fluff up the powder
use one level scoop of powder
dispense the liquid hold the bottle vertically
dispense one drop
one scoop of powder to one drop of liquid
mix w/ a spatula 10 sec
working time 2 min
set in 4 min
Vitrebond Plus
(this or ketac over calcium hydroxide - dycal)
Remove the cap
dispense the two pastes - one click of the dispenser
clean off the dispenser tips and recap
mix w/ a spatula - 10 sec
working time is 2 min 30 sec
the cement can be applied to the area of the prep w/ a small ball burnisher
20 sec cure
