Class 3 Composite Resin

composite resin pros

superior esthetics, adequate strength, and allows for conservative preps

indications and contraindications for class 3 prep

indications = restoration of carious lesions

contraindications = cannot adequately isolate tooth

purpose of pre-wedge

re-establishes a visually closed proximal contact

3 main goals of tooth prep

1. obtain access to lesion

2. remove faulty structure

3. make convenience form

faulty tooth structure

- caries

- infected dentin/ enamel

- defective restorative materials

facial access indications

- lesion is facial

- irregular tooth alignment/ rotation

- extensive lesion extends to facial surface

- pre-existing faulty restoration on facial

lingual access benefits

1. facial enamel is preserved

2. shade matching is less critical

3. restoration aging is less aparent

with lingual access, what is unique about unsupported enamel?

unsupported enamel CAN be preserved

initial bur + vision for class 3 prep

#330 or #2 round bur

indirect vision

what bur can be used for very small class 3 lesions?

#1 round bur

do not prepare completely through ___ in the facial direction

interproximal contact

called "tunneling"

after initiating access, what changes with your bur?

bur angulation/ position will change to move facially

when possible, class 3 prep should NOT

1. include entire proximal area (in I-G direction)

2. extend to the facial surface

3. extend sub-gingivally

axial extension class 3 prep is dictated by

carious lesion

if you're doing a small class 3 prep it will be ___ shaped, with ___ walls, and only have __ if desired

- scoop shaped

- no uniform axial wall

- bevels only as desired

if you're doing a large class 3 prep you need to develop ___ and include ___

walls (B, L, I, G, A)

bevels (45º for 0.5mm)

inciso-gingival length varies for each tooth based on

1. contact locations

2. embrasure shapes/ sizes

3. tooth position/ rotation

incisal wall is into the

contact zone

facial extension measurement class 3

1.5-2.5mm

axial depth measurement class 3

0.75-1.25mm

**M-D "width"

class 3 outline form has a

smooth oblong curve

incisal extension should be a minimum of

halfway into the contact point

ideal gingival extension

0.5mm beyond contact

primary modifier to position and extension

carious extension

outline should preserve the

lingual marginal ridge

class 3 resistance form

rounded internal line angles

class 3 retention form

- 0.5mm caovsurface bevel

- preparation design w/ distinct walls

- enamel/ dentin bonding

class 3 convenience form

mesio-distal extension (axial depth) removes all infected tooth structure + insert restorative materials

mesio distal extension is the same as

axial depth

inciso-gingival measurement is defined by

incisal/ contact area + gingival clearance parameters

should gingival contact be broken?

yes, ideally 0.5mm

margins should be

smooth, continuous, beveled (0.5mm), and terminate on sound tooth structure

measurement of axial wall depth

1.25mm

what walls are present in a class 3 prep?

facial, lingual, gingival, incisal, axial

matrix/ mylar strip purpose

confine restorative material + help develop axial tooth contours

mylar strip is ___ but the axial surface is ___

flat

convex

**pay attention

use a mylar strip with a

wedge

purpose of a wedge

- hold matrix in place

- separate teeth

- prevent gingival overhangs

how to place wedge

use cotton pliers and place opposite from access

type of adhesive used for class 3

scotch bond

steps for adhesive placement

1. clean and isolate tooth

2. etch for 15 sec (enamel first then dentin)

3. rinse etch 15 sec

4. apply scotchbond in a scurbbing motion for 20 sec

5. air thin for 5 sec

6. light cure 20 sec

7. place composite

8. light cure 20 sec per increment

when can you extend the preparation?

if the prep margins end on decalcified enamel (explorer can penetrate)