Goodacre 2001 Principles of Tooth Prep

Question 1

1. Who first published on total occlusal convergence? What numbers?
2. Who offered different numbers?
3. What TOC does Goodacre, Campagni, and Aquilino recommend?
4. Which authors did research to recommend these numbers?
5. TOC is important in what two ways for a crown’s resistance to dislodgement?

Answer 1

1. 1923 Prothero 2-5 degrees
2. 1994 Wilson and Chan 6-12 degrees
3. 10-20 degrees ToC
4. Dodge, Shillingberg
5. Resistance to lateral forces and retention along the path of insertion

Question 2

1. Who originally published on “critical convergence angles”?
2. For a 10 mm diameter molar tooth prep, what occlusocervical dimension and TOC was found sufficient from that study?
3. Which two authors countered this to say it was inadequate and recommended greater occlusal dimension?

Answer 2

1. Parker 1988
2. 10 mm diameter molar tooth prep with 3 mm of occlussocervical dimension and 17.4 degrees of less of TOC
3. Woolsey and Matich found that 3 mm of OC dimension was enough resistance but only at 10 degrees TOC. Insufficient at 20, so study supports greater dimension.

Question 3

1. What factor leads to anteriors and premolars having adequate resistance despite variations in prepared tooth form and dimensions?
2. Why do molars have typically less resistance with typical preparations?
3. What’s recommend OC/Fl ratio for all teeth?
4. What 1984 study is this based on on?

Answer 3

1. Favorable OC/FL ratios.
2. Molars have larger faciolingual dimension and shorter occlusocervical dimension to produce a lower ratio and poor resistance to dislodgment. Also greater TOC.
3. 0.4 ratio
4. Weed and Baez 1984- inadequate crown resistance with 10 mm die, 3.5 mm OC dimension, 22 degrees TOC.

Question 4

1. After anatomic reduction, teeth have what shapes?
2. What authors in 1978 recommended where proximal grooves should be to provide complete resistance to faciolingual forces?

Answer 4

1. Mand molars: rectangular, Max molar: rhomboid, Premolar and anteriors: Oval
2. Woolsey and Matich; proximal groove

Question 5

1. Garguilo 1961 proposed that what apparatus should be 2 mm?
2. What authors discussed this relation further and coined “biologic width”

Answer 5

1. Dimension of epithelial attachment combined with connective tissue attachment occlusal to bone
2. Cohen and Ross 1968

Question 6

1. Malament and Socransky 1999 found what in regards to strength of ceramic crowns and thickness? (for DICOR crowns)

Answer 6

1. Unable to correlate failure of restorations with thickness when bonded to prepared teeth with resinous cement. No difference between those less than 1 mm thick and greater than 1.5. Recommended to reduce based on ceramic thickness required to get color/contour.