title: The effect of instrument lubricant on the diametral tensile strength and water uptake of posterior composite restorative material.
abstract: This in-vitro study investigated the effect of 'instrument lubricants' used during placement of composite restorative material, on the diametral tensile strength (DTS) and water uptake of composite specimens.
  
  
  
  300 posterior composite cylindrical specimens were manufactured: 60 with each instrument lubricant (ethanol, 3-step, 2-step and 1-step 'bonding agent') and 60 with no lubricant (controls). Each set of 60 specimens was evenly allocated to one of the following test groups (n=100/group): Group 1 - tested for DTS immediately after manufacture; Groups 2 and 3 - tested for DTS after immersion in phosphate-buffered saline (PBS) for 1 and 12-weeks respectively, using a Universal Instron machine. Water uptake was assessed gravimetrically. Data were statistically analysed with two-way ANOVA and Tukey's post hoc test (α=0.05).
  
  
  
  The mean DTS and percentage weight change of composite specimens ranged between 32.49-53.14MPa and 0.51-1.36% and varied with lubricant used and time incubated in PBS. All control groups exhibited significantly higher DTS (MPa) (groups 1-3: 53.17±1.78; 50.64±1.85; 45.17±1.77) and lower percentage weight change (groups 2-3: 0.51±0.03; 0.61±0.01) than specimens placed with an instrument lubricant, with significant differences between certain lubricant groups.
  
  
  
  Data from the present study suggest that the use of instrument lubricant may adversely effect the DTS and water uptake of composite restorative material.
  
  
  
  The use of instrument lubricants to aid composite placement is widespread however based on the data obtained it is suggested that discontinuing or limiting the use of instrument lubricants, and if necessary using the 'bonding agent' from a 3-step adhesive system is recommended as results suggest this has the least deleterious effect upon material properties.​.
authors.affiliation: Barts & the London School of Medicine and Dentistry, Dental Physical Sciences, Institute of Dentistry, Francis Bancroft Building, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom. Electronic address: jaymit.patel@nhs.net.
authors.forename: J
authors.initials: J
authors.lastname: Patel
authors.affiliation: Barts & the London School of Medicine and Dentistry, Dental Physical Sciences, Institute of Dentistry, Francis Bancroft Building, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Granger
authors.affiliation: Barts & the London School of Medicine and Dentistry, Dental Physical Sciences, Institute of Dentistry, Francis Bancroft Building, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Parker
authors.affiliation: Barts & the London School of Medicine and Dentistry, Dental Physical Sciences, Institute of Dentistry, Francis Bancroft Building, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Patel
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods; D003762:Dental Instruments; D003764:Dental Materials / Q000737:chemistry*; D054327:Lubricants / Q000737:chemistry*; D008153:Lubrication; D008422:Materials Testing; D013718:Tensile Strength; D014867:Water / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D054327:Lubricants; D014867:Water
keywords: Dental composite; Dental materials; Diametral tensile strength; Instrument lubricant; Material properties; Water uptake