title: MTA and F-doped MTA cements used as sealers with warm gutta-percha. Long-term study of sealing ability.
abstract: OBJECTIVE
  To evaluate the long-term sealing ability (up to 6 months) of two experimental calcium silicate MTA cements used as root canal sealers in association with warm gutta-percha.
  
  
  METHODS
  Calcium silicate (MTA) and calcium-fluoro-silicate powders were prepared. Sodium fluoride was included in FMTA (Fluoride-doped Mineral Trioxide Aggregate) as an expansive and retardant agent. Single-rooted teeth were instrumented with NiTi rotary instruments, filled with warm gutta-percha in association with one of the experimental sealers or with AH Plus as a control (n = 20 for each sealer) and stored at 37 °C. Sealing was assessed at 24, 48 h, 1, 2 weeks and 1, 3, 6 months by a fluid filtration method. Scanning electron microscopy with energy dispersive analysis (SEM/EDX) was used to study the dentine/sealer interface of roots stored for 6 months and the surface of cement disks stored for 24 h.
  
  
  RESULTS
  All sealers revealed a statistically significant reduction (P < 0.05) in fluid filtration after the first 2 weeks. No statistically significant differences were observed between FMTA and AH Plus at all analysis times. At short times (24, 48-h), no statistically significant differences were found between the experimental cements and AH Plus. At long-term evaluations (1, 3, 6 months), FMTA and AH Plus sealed significantly better (P < 0.05) than MTA. FMTA was associated with lower fluid filtration rates, and the seal was stable from 48 h to 6 months, thus proving the most effective material. Scanning electron microscopy with energy dispersive analysis of root sections filled with calcium silicate sealers revealed the formation of a blend layer of gutta-percha and cement consequent to the warm gutta-percha condensation technique. Scanning electron microscopy with energy dispersive analysis of 24-h-stored disks identified a Ca-rich coating on the outer surface consisting of globular particles (calcium hydroxide and calcium carbonate), and a deeper internal Ca- and Si-rich region consisting of needle-like ettringite crystals and round formations of calcium silicate hydrate gel.
  
  
  CONCLUSIONS
  Fluoride-doped MTA demonstrated stable sealing during a period of up to 6 months and significantly better than conventional calcium silicate MTA cements and comparable to AH Plus. The study supports the suitability of calcium silicate MTA cements as sealers in association with warm gutta-percha for root filling.
authors.affiliation: Laboratory of Biomaterials and Oral Pathology of Endodontic Clinical Section, Department of Odontostomatological Sciences, University of Bologna, Bologna, Italy. mgiovanna.gandolfi@unibo.it
authors.forename: M G
authors.initials: MG
authors.lastname: Gandolfi
authors.forename: C
authors.initials: C
authors.lastname: Prati
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry*; D002124:Calcium Fluoride / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry*; D003461:Crystallography; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D004338:Drug Combinations; D004577:Electron Probe Microanalysis; D004853:Epoxy Resins / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry*; D006171:Gutta-Percha / Q000737:chemistry*; D006801:Humans; D008137:Longitudinal Studies; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D012387:Root Canal Filling Materials / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation; D017640:Silicates / Q000737:chemistry*; D012969:Sodium Fluoride / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D002327:Cariostatic Agents; D004338:Drug Combinations; D004853:Epoxy Resins; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C534916:epoxy resin-based root canal sealer; C086631:mineral trioxide aggregate; D012969:Sodium Fluoride; D006171:Gutta-Percha; D002119:Calcium Carbonate; D002124:Calcium Fluoride; D002126:Calcium Hydroxide; D005459:Fluorides; C031293:calcium silicate