Preparation Review Flashcards
How do you place a rubber dam?
- Prep work
o Punch holes in rubber
o Check contacts for floss shredding
- Smooth contacts if necessary
o Mark occlusion BEFORE placing dam - Place clamp on tooth
- Place dam over entire clamp
o Can do with or without frame in place - Stretch dam through contacts
o Floss between contacts - Invert dam
o Delicately blow air around cervical area and push rubber into sulcus with plastic instrument - Ligate anterior tooth
o Ligate with ligatures or piece of rubber dam cut and placed interproximal
What is the most optimal method of isolation?
Rubber dam
What is the anatomy of enamel rod orientation?
Larger diameter near surface, smaller near dentin borders
Should you leave unsupported enamel?
DO NOT LEAVE UNSUPPORTED ENAMEL
How are enamel rods and dentin in relation to eachother?
Enamel rods are perpendicular to long axis and radiate outward from dentin
Where does enamel thickness vary?
By location and tooth types
What percent of enamel is made of hydroxyapatite?
90-92% hydroxyapatite
How would you describe enamel?
Strong and Brittle
What is the largest portion of the tooth?
Dentin
Where is dentin located?
In both the coronal and root portions of tooth
What forms the walls of pulp chamers?
Dentin
How does dentin hardness compare to enamel?
1/5 of enamel
Where is dentin most hard?
Near DEJ than near pulp
What percent of dentin is made of hydroxyapatite?
50% hydroxyapatite
What is dentinal sensitivity?
Fluid movement in tubules
Where should you aim to approach a class 3 prep and why?
from lingual when possible (esthetics)
Is it accepptable to leave unsupported enamel on a class III prep?
May be in the facial or incisal
What should you preserve in a class 3 prep?
Incisal contact
Where is the outline form of a class 3 prep?
PERPENDICULAR to long axis of tooth (not lingual surface)
What is the inciso gingival height of a class 3 prep on the lateral and central?
1.5 mm on lateral
2.0 mm on central
What is the mesial distal width of a class 3 prep on the lateral and central?
1.0 mm on lateral
1.5 mm on central
What contact is broken on a class 3?
Gingival contact
What part of the tooth are retention points/groove added?
only in dentin at depth of 1⁄4 round bur
Where are the retention points/grooves on a class 3?
Point is incisal
Groove is gingival
Where is the bevel on a class 3?
1 mm 45 degree bevel is placed on the lingual (or facial)
Describe the facial contact on a class 3
Facial contact is minimally broken so it can be seen slightly from facial
Why is the axis of entry important on preparations?
For retention form to insure proper convergenct
Also important to ensure enamel rods aren’t undermined
What is the purpose of the reverse S curve in amalgam?
Reverse S curve helps resist fracture of amalgam restoration by increasing the bulk of amalgam, reducing its brittleness and increasing its strength
