title: Are encapsulated anterior glass-ionomer restoratives better than their hand-mixed equivalents?
abstract: OBJECTIVE
  The performance of encapsulated anterior GI restoratives were compared with their hand-mixed equivalents for the range of powder to liquid mixing ratios routinely encountered clinically. The clinically induced variability of powder to liquid mixing variations of an anhydrous GI restorative formulation was also compared with conventional GI restorative formulations that contained a polyalkenoic acidic liquid.
  
  
  METHODS
  Mean compressive fracture strengths, mean elastic moduli and mean total volumetric wear were determined for the encapsulated anterior GI restoratives mechanically mixed in a Capmix or Rotomix machine and the hand-mixed GI restoratives prepared with powder contents reduced from that recommended by the manufacturer (100%) in 10% increments to 50% for a constant weight of liquid. Multiple comparisons of the group means were made using a one-way analysis of variance (ANOVA) and Tukey's multiple range tests employed at P<0.05.
  
  
  RESULTS
  For the encapsulated GI restoratives, the mean compressive fracture strength, mean elastic modulus and in-vitro wear resistance were significantly increased compared with their hand-mixed equivalents prepared with powder contents below that recommended by the manufacturers. The conventional GI restoratives resulted in a linear deterioration (R2>0.95) of the mean compressive fracture strength and mean elastic modulus with powder content compared with the bi-modal deterioration for the anhydrous GI restorative.
  
  
  CONCLUSIONS
  Encapsulated anterior GI restoratives outperform their hand-mixed equivalents for the range of powder to liquid mixing ratios routinely encountered clinically such that they are advocated for use in clinical practice. Anhydrous GI restorative formulations are more susceptible to clinically induced variability on mixing compared with conventional GI restorative formulations that contained a polyalkenoic acidic liquid.
authors.affiliation: Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Dublin 2, Ireland. adam.dowling@dental.tcd.ie
authors.forename: Adam H
authors.initials: AH
authors.lastname: Dowling
authors.forename: Garry J P
authors.initials: GJ
authors.lastname: Fleming
mesh_terms: D002214:Capsules; D002626:Chemistry, Pharmaceutical; D019245:Compressive Strength; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent / Q000295:instrumentation; D055119:Elastic Modulus; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008298:Maleates / Q000737:chemistry; D008422:Materials Testing; D011208:Powders / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
chemical_list: D002214:Capsules; C501420:Chemfil Superior; D005899:Glass Ionomer Cements; D008298:Maleates; D011208:Powders; D012996:Solutions; C084541:Fuji glass-ionomer lining cement; C040964:Ketac-Fil