title: Time-based lateral hygroscopic expansion of a water-expandable endodontic obturation point.
abstract: OBJECTIVE
  This study compared the time-based lateral expansion of two sizes and two batches of water-expandable obturation points (CPoint, EndoTechnologies, LLC) and a similar-sized gutta-percha point (control) at various distances from the point apex: 5, 10, and 15mm.
  
  
  METHODS
  Two batches of sizes 25 and 40 (0.06 taper) CPoints and a single lot of size 40 (0.06 taper) gutta-percha were tested (N=5). Points were fixed to the bottom of a Petri dish, and digital images of each point location were obtained under 50× magnification, which also captured a calibrated linear scale reticule. After imaging each dry cone location, 10mL of water was added, and images were obtained at various time points: 20 and 40min, 1, 2, 3, 4, 5, 6, 7, 8, and 24h. Between measurements, dishes were stored at 37°C. Side-to-side dimension of each point was determined using imaging software
  
  
  RESULTS
  No significant differences (p>0.05) in lateral dimension at each tip distance between batches of similar-sized CPoint samples were found (2-tailed unpaired Student's t-test). Changes in CPoint dimension were significantly higher (p<0.05) for both sizes at each tip distance after 20min of water immersion (one-factor repeated-measures ANOVA; Tukey test). Gutta-percha did not significantly change from the dry value during water immersion (p>0.05).
  
  
  CONCLUSIONS
  When exposed to water, the lateral expansion of a new hydrophilic endodontic obturation point significantly increases in dimension within 20min, whereas a conventional gutta-percha point does not.
authors.affiliation: Department of Endodontics, Georgia Regents University, Augusta, GA, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Didato
authors.forename: Ashraf A
authors.initials: AA
authors.lastname: Eid
authors.forename: Martin D
authors.initials: MD
authors.lastname: Levin
authors.forename: Sara
authors.initials: S
authors.lastname: Khan
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Rueggeberg
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D006171:Gutta-Percha / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007101:Immersion; D008422:Materials Testing; D008853:Microscopy; D009757:Nylons / Q000737:chemistry*; D012387:Root Canal Filling Materials / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D017155:Wettability
chemical_list: D000180:Acrylic Resins; C000589422:CPoint; D009757:Nylons; D012387:Root Canal Filling Materials; D014867:Water; D006171:Gutta-Percha
keywords: CPoint; Endodontics; Hygroscopic expansion; Lateral expansion; Obturation