Put posts in their place:
When it comes to post cementation, it’s important to choose the right materials. A combination of the right pretreatment, a self-adhesive cement and fiber post that doesn’t require pretreatment can help reduce steps and the chance of mistakes, as well as simplify the procedure.
Some clinicians still use adhesive together with cement, but this can cause issues. Adhesive needs to be air dried, which is tricky in a root canal and adds an extra step to your procedure. Plus, adhesive residue, uncured material or remaining propellant can create a risk of voids and interfere with post seating. Plus, the application microbrush is often too thick to go inside the canal, meaning a thinner brush is needed to apply adhesive in a controlled way. Self-adhesive cements like 3M™ RelyX™ Unicem 2 Self-Adhesive Resin Cement or 3M™ RelyX™ Universal Resin Cement, on the other hand, have standardized application tips which allow for good void-free distribution from the bottom up.
Before placement, use ≤5% sodium hypochlorite solution to clean the canal. It’s important to rinse the prep with water thoroughly – do not let the hypochlorite solution remain in the canal, as it could weaken the bond. Use a paper point to remove excess water without overdrying the canal. You want the dentin to remain moist for an optimal bond. After cleaning the treatment surfaces, there are two easy steps to follow for successful post placement.
1. Apply the self-adhesive cement using the provided root canal mixing tip attachments, keeping the tip immersed in the cement at all times as you gradually work your way up from the bottom of the canal to the top (fig. 5). This technique enables void-free application and an optimal bond. If you simply place cement on the post and place it directly into canal, the air in the canal has no way to get out and you can end up with voids. Using an elongation tip, such as those featured with RelyX Unicem 2 Self-Adhesive Resin Cement or RelyX Universal Resin Cement, can help reach the bottom of the canal. RelyX Universal Resin Cement’s longer and thinner elongation tip, in particular, offers an easier way to apply cement into the root canal (fig. 6).
Do not overfill the canal – if you place too much cement, it will overflow when inserting the post and get onto the dentin, which will interfere with adhesive application. Only place enough cement so that you can easily remove excess after the post is inserted. Do not use a lentulo bur, the cement will set too fast.

Figure 5: Application of self-adhesive cement

Figure 6: Side-by-side comparison of the standard elongation tip attachment (left) to the 3M™ RelyX™ Universal Resin Cement elongation tip (right).
2. Insert the shortened fiber post once – do not move up and down, it could create voids (fig. 7). Once placed, either tack-cure excess cement and then remove it or remove excess cement with a microbrush and hold post down to light cure. Light cure from the top through the post, according to the cement manufacturer’s instructions. Use a good, well-tested curing light with a stable output that to ensure a thorough cure, such as 3M™ Elipar™ DeepCure-S LED Curing Light.
Always use a dual-cure cement to ensure thorough polymerization, even in areas where the light does not sufficiently reach. Cements like RelyX Universal Resin Cement have a powerful self-cure component, providing additional insurance of adequate polymerization – no need to worry about potential voids or uncured material as with the application of a separate adhesive in the root canal.

Figure 7: Insertion of shortened fiber post.
From cementation to buildup, make sure carefully time your process – do not prepare the buildup too early. Wait a minimum of 6 minutes, ideally 10, for the cement to polymerize to avoid disrupting bonding. Don’t just place the post and start preparing. Cement, wait 10 minutes, then buildup.