Ions-releasing and ability/inability to form apatite of endodontic sealers.

Objectives: All endodontic sealers may be in contact with apical bone and must have high bioactivity and biological behaviour. The in vitro bioactive behaviour of commercial endodontic sealers for root canal therapy was investigated in real-time on wet fresh and set cements by using ESEM/EDX and micro-Raman. Methods: AH Plus (Dentsply, USA), Calcibiotic Root Canal Sealer - CRCS (Hygienic, USA), Pulp Canal Sealer - PCS and SealApex (Kerr, USA), and three calcium-silicate materials ProRoot MTA (Dentsply, USA), Tech Biosealer Endo (Isasan, Italy) and an experimental flowable MTA (University of Bologna, Italy) were tested. Cement discs were prepared according with manufacturer directions and analyzed in wet conditions by ESEM/EDX and micro-Raman immediately after their preparation (fresh) and after soaking at 37°C in simulated body fluid (HBSS) for 24h and 28d. The release of calcium-&-hydroxyl-ions in soaking water was tested at short times (3,24h and 7d) and at long times (14,28d). Results: Fresh wet samples displayed the elements of material composition. The surface of calcium-silicate cements resulted covered by apatite spherulitic deposits already after 24h and a continuous apatite coating at longer times. No apatite was detected neither on PCS nor on SealApex. CRCS showed some/rare apatite deposits since 24h and AH Plus revealed sporadic apatite deposits after 28d. Calcium-silicate materials and SealApex showed higher calcium-releasing than CRCS. AH Plus and PCS do not released calcium. Only calcium-silicate sealers released hydroxyl-ions. Conclusions: Commercial endodontic sealers resulted unable to induce formation of bone-like apatite layer and suggest a lack or modest level of bioactivity. On the contrary, ProRoot MTA and calcium-silicate cements demonstrated earlier bioactivity.