- The most critical characteristic of dental cements for ensuring effective bonding of orthodontic brackets is the shear bond strength.
- This property measures the cement's ability to resist forces parallel to the bonding surface, which is essential during orthodontic treatment as brackets are subjected to various mechanical stresses from chewing, tooth movement, and appliance adjustments.

- While other factors such as setting time, solubility in oral fluids, and thermal expansion coefficient are important for overall cement performance and durability, they do not directly impact the primary function of holding the bracket firmly in place.

- Shear bond strength ensures that the brackets remain securely attached throughout the treatment period.
- A cement with inadequate shear bond strength increases the risk of bracket failure, leading to treatment delays and additional appointments.
- Setting time affects working efficiency but is less critical for long-term retention.
- Solubility impacts longevity but insufficient bond strength will cause failure before solubility becomes an issue.
- Thermal expansion coefficient is relevant for minimizing stress due to temperature changes but is secondary to the bonding capacity.

In summary, the ability of the dental cement to resist shear forces (shear bond strength) is paramount for effective and reliable orthodontic bracket bonding.

Reference: Orthodontics: Current Principles and Techniques, 6th Edition, Chapter 10 - Bonding Techniques, Page 345