title: Expansion of gutta-percha in contact with various concentrations of zinc oxide-eugenol sealer: a three-dimensional volumetric study.
abstract: BACKGROUND
  Successful endodontic treatment depends on achievement of a fluid-tight seal that is not possible solely with gutta-percha and requires the use of a root canal sealer. Eugenol, which is a principal component in zinc oxide-eugenol (ZOE) based sealers, is reported to produce a volumetric expansion of gutta-percha. The aim of this study was to evaluate the three-dimensional expansion of gutta-percha at various powder/liquid ratios of ZOE-based sealer by using spiral computed tomography (SCT).
  
  
  METHODS
  Fifty freshly extracted premolars with single canal were decoronated and instrumented by using RaCe rotary instruments (35/06). The teeth were divided into 5 groups of 10 each, and volume of the canal was measured by using SCT. The teeth were then obturated with gutta-percha cones (35/04) in groups ZE 1:1 to ZE 1:4 with Pulp Canal Sealer EWT (ZOE-based) with powder/liquid ratio of 1:1, 1:2, 1:3, and 1:4, respectively, and gutta-percha alone in control group (no sealer group). The filled volume in each canal was measured by using SCT 1 day, 7 days, and 1 month after obturation, and percentages of obturated volume and of volume changes in groups over time were calculated. The data were statistically analyzed by using one-way analysis of variance and post hoc multiple comparison tests.
  
  
  RESULTS
  The groups ZE 1:2 and ZE 1:3 gave the highest mean volume values during a 1-month period and were significantly different in comparison with groups ZE 1:1 and ZE 1:4 (P < .05).
  
  
  CONCLUSIONS
  Increasing the ratio of eugenol in sealer resulted in volumetric increase of gutta-percha. However, further studies should be performed to confirm the expansion and sealing ability of gutta-percha of the size corresponding to the prepared canal, leading to the achievement of fluid impervious seal.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Mamata Dental College, Andhra Pradesh, India.
authors.forename: Veeramachaneni
authors.initials: V
authors.lastname: Chandrasekhar
authors.forename: Pradeep Kumar
authors.initials: PK
authors.lastname: Morishetty
authors.forename: Swarna Latha
authors.initials: SL
authors.lastname: Metla
authors.forename: R V S Chakradhar
authors.initials: RV
authors.lastname: Raju
mesh_terms: D001641:Bicuspid / Q000000981:diagnostic imaging; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging; D006171:Gutta-Percha / Q000737:chemistry*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D011208:Powders; D012387:Root Canal Filling Materials / Q000737:chemistry*; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D012996:Solutions; D013499:Surface Properties; D013997:Time Factors; D036542:Tomography, Spiral Computed; D015035:Zinc Oxide-Eugenol Cement / Q000737:chemistry*
chemical_list: D011208:Powders; D012387:Root Canal Filling Materials; D012996:Solutions; D015035:Zinc Oxide-Eugenol Cement; D006171:Gutta-Percha