Effect of timing and method of post space preparation on sealing ability of remaining root filling material: in vitro microbiological study.
OBJECTIVE
To evaluate the effect of timing (immediate versus delayed) and technique of post space preparation on the ability of the residual root canal obturation to prevent coronal bacterial leakage.


METHODS
Sixty-six single-rooted teeth were decoronated at the cementoenamel junction. The canals were prepared according to a step-back technique and were filled with thermoplasticized gutta-percha and AH Plus endodontic sealer (Dentsply De Trey). The root segments were randomly assigned to 8 groups. The positive controls (n = 3) were instrumented but not obturated. The negative controls (n = 3) were instrumented, obturated and sealed with Cavit (3M ESPE). In the other 6 groups (n = 10 each), the post space was prepared either immediately after obturation or 7 days later using LA Axxess burs (SybronEndo) (groups 1 and 2), heated pluggers (groups 3 and 4) or solvent delivered with a hand file (groups 5 and 6). The external surface of all roots was rendered waterproof with nail varnish. Custom-made dual-chamber devices were used to evaluate leakage. The coronal third of the prepared root canal was kept in contact with artificial saliva contaminated with Enterococcus faecalis, and the root apex was submerged in tryptic soy agar medium. The root assemblies were stored at 37 degrees C and were monitored daily over a 90-day period. The occurrence of turbidity in the medium was deemed to indicate bacterial leakage, from which failure of the seal was inferred.


RESULTS
Throughout the experimental period, there was no significant difference (p = 0.094) among the preparation techniques, either immediate or delayed, in terms of bacterial leakage.


CONCLUSIONS
Immediate and delayed post space preparation yielded similar outcomes in terms of the canal seal. Regardless of the timing and the technique of post space preparation, coronal bacterial leakage occurred over time.
Universidade Federal do Rio Grande do Sul, Faculdade de Odontologia, Rua Ramiro Barcelos, 2492, Centro, 90035-003 Porto Alegre, RS, Brazil. fakera@terra.com.br
Fabiana Soares
FS
Grecca
Angela Rezende Gomes
AR
Rosa
Maximiliano Schünke
MS
Gomes
Clarissa Fatturi
CF
Parolo
Jules Renan Dutra
JR
Bemfica
Luis Carlos da Fontoura
LC
Frasca
Marisa
M
Maltz
D002133:Calcium Sulfate / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D003763:Dental Leakage / Q000382:microbiology; D003786:Dental Pulp Cavity / Q000382:microbiology*; D004338:Drug Combinations; D013293:Enterococcus faecalis / Q000302:isolation & purification; D004853:Epoxy Resins / Q000737:chemistry / Q000627:therapeutic use; D006171:Gutta-Percha / Q000737:chemistry / Q000627:therapeutic use; D006801:Humans; D008422:Materials Testing; D011145:Polyvinyls / Q000737:chemistry; D011176:Post and Core Technique; D012387:Root Canal Filling Materials / Q000737:chemistry* / Q000627:therapeutic use; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012464:Saliva, Artificial; D012997:Solvents / Q000627:therapeutic use; D013696:Temperature; D013997:Time Factors; D019227:Tooth Apex / Q000382:microbiology; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*; D015034:Zinc Oxide / Q000737:chemistry
D003738:Dental Cements; D004338:Drug Combinations; D004853:Epoxy Resins; D011145:Polyvinyls; D012387:Root Canal Filling Materials; D012464:Saliva, Artificial; D012997:Solvents; C534916:epoxy resin-based root canal sealer; C020872:Cavit; D006171:Gutta-Percha; D015034:Zinc Oxide; D002133:Calcium Sulfate