Title	Pre-Heating Resin Composite Does Not Result In Restorations With Less Polymerization Shrinkage
Clinical Question	In patients needing composite restorations, do pre-heated resin composites result in less polymerization shrinkage than standard resin composites?
Clinical Bottom Line	Pre-heating composite does not result in a reduction in polymerization shrinkage.
Best Evidence
PubMed ID Author / Year Patient Group Study type (level of evidence) 19081616 Lohbauer/2009 1 brand of composite In Vitro Research Key results More polymerization shrinkage occurs with the pre-heated composite. When pre-heated to 68° Celsius, 2.85% polymerization shrinkage occurred 5 minutes after curing. When cured at 37° Celsius, the polymerization shrinkage was between 2.15-2.20 vol% (p>0.05). Both showed 0% polymerization shrinkage 24 hours after curing. Advantages of pre-heating composites are more likely to be related to placement technique rather than polymerization properties. 21465004 Tantbirojn/2011 2 types of composite with 5 samples each In Vitro Research Key results There was no significant difference in polymerization shrinkage between pre-heated composites and composites cured at room temperature (p>0.05). The marginal increase in hardness and reduction in shrinkage stress is not a result of decreased polymerization shrinkage of pre-heating composites. 19898716 Walter/2009 1 brand of composite In Vitro Research Key results Preheating the composite to 54° Celsius and 68° Celsius resulted in increased shrinkage when compared to a composite cured at room temperature (p <.0001). An increase in polymerization shrinkage with pre-heated composite can be compensated for with superior marginal adaptation of a pre-heated composite by the operator.
Evidence Search	Lohbauer Article:("Composite Resins"[Mesh] AND "Hot Temperature"[Mesh]) AND "Viscosity"[Mesh]Tantbirojn and Walter Articles: ("Composite Resins"[Mesh] AND "Hot Temperature"[Mesh]) AND "Polymerization"[Mesh]
Comments on The Evidence	Lohbauer: All composite samples were similar at start and were present at completion of the trial. The composites were treated under the same conditions, excluding the temperature of the composite before curing and there were 24 hr follow-ups for all samples. The shrinkage was measured at random, but it was not double-blind. No competing interests were present. Tantbirojn: All composite samples were similar at start and were present at completion of the trial. The composites were treated under the same conditions, excluding the temperature before curing. No competing interests were present. Walter: All composite samples were similar at start and were present at completion of the trial. The composites were treated under the same conditions, excluding the temperature before curing. No competing interests were present.
Applicability	The trial is applicable to patients if they are getting restorations with Tetric® EvoCeram, Filtek Z250, Filtek Supreme Plus, or Durafill VS and are cured according to manufacturer recommendations.
Specialty	(General Dentistry) (Restorative Dentistry)
Keywords	Resin composite Temperature Shrinkage
ID#	2241
Date of submission	04/25/2012
E-mail	tamimin@livemail.uthscsa.edu
Author	Nadijah Tamimi
Co-author(s)
Co-author(s) e-mail
Faculty mentor	Kevin M. Gureckis, DMD
Faculty mentor e-mail	gureckis@uthscsa.edu
Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) None available
Comments and Evidence-Based Updates on the CAT (FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) None available