Onlays

Question 1

Posterior Onlay - Definition

Answer 1

An Onlay is a restoration covering at
least one cusp on the occlusal surface
where the morphology is replaced by
another material including ceramic,
gold, amalgam, zirconia.

Question 2

Indications for an Onlay
-When cusps have been undermined by —
-When enamel is available for —
-When there is the presence of — which
are too far apart to repair with composite or amalgam
-Lack of supporting — under a cusp
-Heavy —
—- cusps in an esthetically oriented patient.
-When remaining tooth structure is less than — of the inter-cuspal distance

Answer 2

caries
etch and bonding
horizontal cracks
dentin
occlusion
Discolored
1/3 to ½

Question 3

-Done well, research has shown that an onlay with appropriate cusp coverage

Answer 3

greatly increases the strength of the natural tooth prior to the onlay

Question 4

Contraindications for an Onlay

Answer 4

-Patient has poor oral hygiene
-Patient is severe bruxer
-More than 2/3 of the occlusal table requires restoration to
support the onlay, a complete crown is generally
recommended.
-Inability to create sufficient bulk for ceramic material in the
preparation and with opposing occlusion. Need 2mm of
reduction for ceramics.
-Inability to maintain a dry field.

Question 5

-In general, the adhesive resin cements used for onlays are

Answer 5

technique sensitive and may not be appropriate for every
scenario.

Question 6

Why choose an Onlay?

Answer 6

Conservation of tooth structure is the
primary reason.

Question 7

Onlays are used primarily as a

Answer 7

conservative
alternative to crowns.

Question 8

Leaving the the tooth walls and additional
tooth structure allows for

Answer 8

further
restoration preparations in the future.

Question 9

Once you cut a crown prep,

Answer 9

you can’t do
anything else but another crown.

Question 10

With an onlay, there is still

Answer 10

tooth structure
available to extend the onlay or move
to a crown if the restoration fails.

Question 11

In the past, onlays were not used as often as they were
indicated.
(3)

Answer 11

-More technical preparation
-Difficult to temporize
-More precise fit and therefore more room for
error to occur

Question 12

In the past, onlays were not used as often as they were
indicated.
-More technical preparation
-Difficult to temporize
-More precise fit and therefore more room for
error to occur
-Therefore, the majority of dentists chose to prepare
these teeth for

Answer 12

crowns because the crowns are
easier and quicker to prepare and temporize.
-In addition, some insurances would not pay for
onlays or inlays but would pay for crowns.

Question 13

Now, with more and more dentists purchasing and
using digital scanning with an in office milling,

Answer 13

onlays are used more because the digital scanning
and milling without the temporization issues have
brought back this more conservative restoration by
eliminating the more challenging previous
concern.

Question 14

Here we see a Gold Onlay which preserves the
(2)
Note the marginal adaptation! Only Gold can be
smoothed and burnished in a fashion to make
these margins as perfect as seen here.
This technique is not taught very often anymore.
— are not nearly as capable as attaining
margins of this integrity. Many onlay margins
require the — to do the final sealing
of the margins.
However, with all those challenges, onlays can be
excellent restorations when done well.

Answer 14

facial tooth structure to enhance the esthetics.

Ceramics
resin cement

Question 15

Note – This onlay tooth preparation appears much like a
crown preparation for this full coverage onlay. What hasn’t
been reduced like a crown are the

Answer 15

gingival halves of the
tooth wall.