Gold Onlays Flashcards
1
Q
what is the progression of prep/restoration
A
- MO composite prep
- MOD composite prep
- MOD inlay- indirect (composite or porcelain)
- MOD gold inlay
- MOD gold/ceramic/zirconia onlay
- full gold/ceramic/zirconia crown
2
Q
describe the MOD indirect (composite or porcelain) prep
A
- diverge walls 5-15 deegrees
- more divergence than gold inlay prep
- axial walls cannot be undercut
- break buccal contact
- smooth gingival margin, no bevels
- have enough clearance for model and die work
- internal line angles are definitely rounded
- exit angles still 90 degrees
3
Q
how large is the isthmus for the MOD indirect inlay
A
2mm minimum
4
Q
describe the MOD gold inlay prep
A
- less divergence
- short walls have a 2 degree divergence and long walls a 5-7 degree divergence
- bevel occlusal 1mm long
- bevel gingival -1mm long
- bevel axial pulpal line angle- no sharp angles
- axial walls cannot be converged (undercut) but must be straightened up and diverged
- retention is from internal axial walls
- there is no bonding to tooth so internal walls are more retentive and less divergence than indirect composite or porcelain inlays
5
Q
what are the indications for various materials for inlays
A
no specific indications for a gold inlay; amalgam or composite can be used in vitrually every situation a gold inlay can be used
6
Q
what are the indications for an onlay
A
- large carious lesions or defective restorations- when restoration replaces more than 2/3 of the intercuspal distance
- cracked teeth- incomplete vertical fracture of teeth (not in pulp chamber)
- endo treated teeth -after RCT teeth dehydrate and become more prone to fracture; cuspal coverage is a must after endo treatment
- re-establishment of occlusal plane- can significantly adjust plane of occlusion for a single tooth or entire arch without placing full coverage
- prevention of galvanism
- patient preference-
7
Q
what is galvanism
A
gold very resistant to tarnish and corrosion; if pt already has numerous gold restorations, continue to use gold
8
Q
why would a pt prefer gold over amalgam
A
more esthetic and no mercury
9
Q
what are the advantages of onlays
A
- strength- little possibility of fracture or marginal breakdown over time and can support occlusal forces
- wear- gold will not damage adjacent teeth; will deform over time under a lot of loading
- porcelain/zirconia can cause significant damage to opposing teeth under occlusal forces, especially under heavy bruxism forces
- anatomy- lab fabrication allows conrol of contact contour and anatomy
- conservative prep
- cementation- can be cemented with fluoride releasing glass ionomer cement
- longevity- last longer than more other restorations
10
Q
when does the lab have more control of contours
A
with large restorations and when margins are sub gingival
11
Q
what are the disadvantages of an onlay
A
- cost- less than a crown but not usually covered by insurance at full cost
- time technique sensitive- requires two patient visits because of lab
- esthetics- not as esthetic as porcelain or composite restorations
12
Q
when to onlay cusp:
A
- whenever bucco-lingual width of the cavity prep is:
- 1/2 way between central groove and cusp tip consider cuspal coverage
- 2/3 of the way between central groove and the cusp tips must onlay the cusps
- when cusps are undermined after caries removal
- when both marginal ridges have been compromised, consider cuspal coverage
- when patient has a history of fractured teeth
13
Q
describe the prep for an onlay - external form
A
- external form: similar to amalgam with these mods:
- occlusal outline of inlay prep extended to include all non- coalesced fissures
- buccal and lingual proximal walls of box have secondary flare and are divergent occlusally
- no reverse S present on buccal proximal walls
- 30 degree bevel present on gingival cavosurface margin; bevel should blend with the secondary buccal and lingual flare, extends 0.5-1mm
14
Q
describe the prep for an onlay- internal form
A
- occlusal depth is appropriately 1.5mm
- all walls prepared with a 2 degree-5 degree occlusal divergence ( prepared with a #169 and #271 fissure bur)
- rounded internal line angles produced by the #271 bur to relive internal stresses in tooth
- 30 degree bevel placed at occlusal cavosurface of preparation to aid in seating and to make margin of gold burnishable
- any remaining caries or old restorations can be removed with a round bur or spoon
- pulpal and axial wall depths placed entirely in detnin just inside the dentin-enamel junction
15
Q
what is the preparation for an onlay- cuspal coverage
A
- functional cusp- reduce 1.5mm with depth cuts to preserve the incline angle; place counter-bevel to allow adequate thickness of metal (30 degrees) over cusp tip
- non functional cusp- reduce 1mm with depth cuts; counter-bevel placed
- internal buccal/lingual walls less than 1mm tall have only 2 degrees occlusal divergence
16
Q
what is the reverse bevel
A
- facial- non functional bevel
- lingual- functional bevel
- longer reverse bevel
17
Q
where are bases and liners placed and when
A
only on axial wall and pulpal floor when necessary
18
Q
what is placed as a base and liner
A
CaOH placed only in deepest part of prep to protect pulp, glass ionomer (Vitrebond) or composite placed as a base to build the prep to ideal depth and form
19
Q
what are the considerations with bases and liners
A
- should build the prep to ideal form
- should not be placed on the gingival floor
- should not extend onto facial or lingual enamel walls
- should not be relied on for support of restoration
- should not be relied on for retention
- base must be smooth and retained during impression
20
Q
what is the technique with impressions for onlays
A
- use any crown and bridge quality impression material
- place two layers of retraction cord in sulcus adjacent to gingival margin, removing one cord prior to taking impression
- custom trays are the most accurate
21
Q
what provisional restoration is used with onlays
A
- IRM: zinc oxide eugenol placed for inlay preparation; can also be used for onlay preps if permanent restoration will be delivered quickly (within 2 weeks)
22
Q
what are the 3 types of acrylic
A
- polymethacrylate (Jet)
- vinylpolyethylmethacrylate (Trim, Snap)
- Bis-acryl composite - Pro Temp II, Intrgrity
23
Q
what is the direct method for provisional restorations
A
- acrylic provisionals formed in the mouth at time of prep, using template
24
Q
what is the cement used with provisional restorations
A
- both types can be cemented with temp bond or IRM (eugenol does not interact well with acrylic); Tempbond NE or other non-eugenol temporary cements are a better choice
- Durelon (permanent acrylic cement) can be used if retention might be an usse
- CaOH can be used when retention is good (very weak cement)
25
provisionals should be placed with _____ occlusion, Why?
- light
- to prevent supraeruption of tooth and prevent destruction of the provisional by heavy occlusal forces
26
what are the post op instructions for provisional restorations
- pt should be able to function normally with provisional in place with the following modications:
- floss only in the gingival direction, pulling the floss through to the buccal below the contact area
- avoid sticky foods that might pull the provisional restoration from the tooth
- avoid hard foods that could crush the provisional
27
describe the seating of casting before pt arrival
- before pt arrival
- check margins and contacts on the die to ensure proper fit
- inspect internal surface of casting for obvious blebs or bubbles that might interfere with seating
- disinfect casting with surface disinfectant
28
describe the seating of casting after pt arrival
- remove provisional restorations- elevate with spoon just below the contact
- all intra oral manipulation of casting should be done with 2x2 gauze placed at back of the throat to help prevent misadventures
- remove any remaining temporary cement from surface of tooth, leaving any bases in place
- clean tooth with consepsis using a prophy brush
- place the restoration on the tooth and check proximal contacts with lightly waxed floss, relive any heavy contacts with a 12 fluted carbide finishing bur
- inspect the margins of the restoration looking for open margins
- if open margins are found, reinspect internal surface and adjust as needed
- reseat and inspect margins
- remove casting, dry, inspect carefully and adjust any prematurities on slow speed
- check occlusion with accufilm by marking the bite without the casting in placed then with the casting seated, the red ink will be more visible on the gold
- the occlusal markings should be found posterior and anterior to the restoration
- use a boley gauge to check thickness of casting prior to adjusting occlusal surface; if less than 0.5mm thick may need to adjust opposing dentition
- check lateral and protrusive excursions by the same method
- check bite with pt
- use mylar strips as a final check of occlusion
29
what do you do if open margins are still present
remove casting and apply fit checker or occlude to internal surface; replace casting on tooth and have patient close, first in MI, then on a cotton roll
30
what should be found with mylar strips/shimstock
a contact should be found anterior to the restoration that snags or tears the mylar strip; if the strip pulls through in an area that is in contact when casting is not in place, further adjustment is neeeded
31
describe the polishing of the casting
- burnishing: burnish margins on the die or tooth, with any burnisher, working from gold to tooth; this will thin the gold and leave virtually undetectable margins
- slightly short margins can be closed using this method
- a BW can be taken to verify fit
- casting should fit more tightly after burnishing
-re-define occlusal anatomy with small round burs on slow speed and finishing burs on high/slow speed; check thickness of casting with boley gauge before starting and during adjustment to prevent perforation
- restore original finish using Shofu points; tripoli, and rouge
32
describe cementation
- clean casting with steam if needed to remove debris from seating process; disinfect
- cement casting using any permanent crown and brudge cement: ZnPO4, Rely X, SpeedCem
33
what are the post op instructions after cementation
- after removal of excess cement, advise pt not to ear or drink for at least an hour
- eat only soft food on the side of restoration for next 24 hours
- post cementation appt- in one week to verify all cement has been removed
34
