Lesson 3: C-Factor
Avoid adhesive shrinkage and tooth strength problems. Configuration Factor, or C-Factor, is an ordinal measurement of the ratio of an onlay's bonded to unbonded surface area, and can be approximated by the number of bonded "sides" an onlay has.
Dentists have traditionally tried either to do minimally invasive preps when possible, and to drill a deep open box when it's not. The idea behind the box is maximal bond surface area will lead to optimal bond strength. However, post-gel-point shrinkage pulls the adhesive's bond off the box's gingival, axial and lower portions of proximal walls in direct composites. This is because it takes far long for dentinal bonds to mature than bonds to enamel.
Lesson 3, C-Factor, covers all of the following:
- Rebuilding structurally compromised cusps
- Flaring preps across Boyde's lines
- Proper layering technique
- Decoupling dentin and enamel bonding
