Drying the canal with alcohol gave 3.23 MPa, microsuction only 1.23 MPa

The drying protocol decides how well the sealer holds to dentine

When a canal is obturated with a premixed calcium silicate bioceramic sealer, the single-cone technique leaves little room for correction. The bond between sealer and dentine forms in an environment whose moisture the clinician sets with the last move before obturation. That very move, drying the canal, was measured by the team around Idil Ozden in a paper published in Acta Stomatologica Croatica.

Three groups of ten specimens each received a different final step: a paper point, microsuction or 70% isopropyl alcohol. Before that, all thirty extracted maxillary central incisors went through the same route, preparation with nickel-titanium rotary instruments and irrigation with sodium hypochlorite and EDTA, then obturation with the same sealer using the single-cone technique. A week later, 90 sections in total were cut from the coronal, middle and apical thirds for push-out bond strength testing.

The difference was clear (p < 0.001). Isopropyl alcohol gave 3.23 MPa, the paper point 2.97 MPa and microsuction 1.23 MPa. Apical sections held better than coronal and middle ones. Mixed failure mode predominated in all groups, but cohesive failures, those in which only the sealer gives way and not its bond to dentine, were more frequent in the alcohol group and in the paper point group. Scanning electron microscopy showed better sealer adaptation to dentine and fewer voids at the interface in those two groups.

Limitations

This is a laboratory study on extracted teeth, with ten specimens per group and a single type of sealer. The push-out test measures resistance to displacement, not clinical sealing over years.

For the practice

• If you work with bioceramic sealers in endodontics, a paper point and 70% isopropyl alcohol remain the safer choice over microsuction.
• Check your own drying protocol: microsuction gave the lowest bond strength here and the poorest adaptation on microscopy.
• The apical third was not the weak point; lower values were measured in the coronal and middle parts of the canal.