How do you prevent contamination when trying in an indirect restoration in the mouth and what surface treatments are recommended?

Preventing Contamination During Indirect Restoration Try-In

When trying in an indirect restoration intraorally, use strict aseptic technique with gloves and barriers, avoid saliva contamination, and if contamination occurs, clean and re-treat the bonding surface with appropriate protocols before final cementation—silane application should be done once on the clean restoration surface before try-in, and if contamination occurs during try-in, the restoration must be cleaned and the bonding protocol repeated.

Infection Control During Try-In

Standard Precautions Are Mandatory

• Wear medical gloves when contacting saliva or mucous membranes during the try-in procedure 1
• Use additional PPE (protective eyewear, mask, and gown) if spattering of blood or other body fluids is likely 1
• Change gloves between patients and wash hands immediately after glove removal 1

Handling the Restoration

• The indirect restoration should be handled with clean gloves to prevent contamination before try-in 1
• If the restoration contacts saliva during try-in, it becomes contaminated and requires cleaning before final cementation 2, 3

Surface Treatment Protocol

Initial Silane Application (Before Try-In)

• Apply silane to the clean, prepared bonding surface of the restoration according to manufacturer's instructions before the try-in appointment 2, 3
• This initial surface treatment is performed on the uncontaminated restoration 3

Managing Contamination After Try-In

The literature on immediate dentin sealing and indirect restorations indicates that contamination during try-in compromises bond strength 2. While the provided evidence doesn't explicitly address "double silane application," the clinical approach based on adhesive principles is:

• If contamination occurs during try-in: Clean the restoration thoroughly to remove saliva and debris 3
• Re-prepare the bonding surface: The contaminated surface must be cleaned and the bonding protocol repeated 2, 3
• Ethanol cleaning: While not explicitly mentioned in the guidelines for this specific application, ethanol (70% alcohol) is recommended by CDC for cleaning contaminated surfaces and could be used as part of the cleaning protocol before re-silanization 1
• Re-apply surface treatments: After cleaning, reapply silane according to manufacturer's instructions before final cementation 3

Clinical Workflow to Prevent Contamination

Optimal Approach: Minimize Intraoral Try-In

• Use try-in paste or water-soluble gel for fit verification rather than allowing direct saliva contact 3
• Keep try-in time minimal to reduce contamination risk 2
• Consider using a rubber dam or cotton roll isolation during try-in to minimize saliva exposure 2

If Try-In Results in Contamination

1. Remove the restoration and clean thoroughly with appropriate cleaning agents 3
2. Re-treat the bonding surface according to the material-specific protocol 2, 3
3. For ceramic restorations: clean, re-etch (if applicable), and re-silanize 3
4. For composite restorations: clean and re-treat the bonding surface 4, 3
5. Proceed with adhesive cementation using fresh bonding agents 2, 3

Common Pitfalls to Avoid

• Never proceed with final cementation on a saliva-contaminated surface without proper cleaning and re-treatment—this significantly compromises bond strength and long-term success 2
• Do not assume a single try-in with saliva contact is acceptable—contamination must be addressed before final bonding 2, 3
• Avoid prolonged try-in periods that increase contamination risk and compromise the prepared bonding surface 2
• Do not reuse single-use disposable items during the try-in or cementation procedure 1

The key principle is that any contamination during try-in requires complete cleaning and re-treatment of the bonding surface, which may include re-application of silane for ceramic restorations, rather than simply applying silane twice without cleaning 2, 3.