The effect of preheating resin composites on surface hardness: a systematic review and meta-analysis

Abstract

ObjectivesThis paper presents a systematic review and meta-analysis of the effect of preheating on the hardness of nanofilled, nanoceramic, nanohybrid, and microhybrid resin composites.Materials and MethodsAn electronic search of papers on MEDLINE/PubMed, ScienceDirect, and EBSCOhost was performed. Only in vitro studies were included. Non-English studies, case reports, clinical trials, and review articles were excluded. A meta-analysis of the reviewed studies was conducted to quantify differences in the microhardness of the Z250 microhybrid resin composite using the Comprehensive Meta-Analysis software.ResultsOnly 13 studies met the inclusion criteria for this systematic review. The meta-analysis showed that there were significant differences between the non-preheated and preheated modes for both the top and bottom surfaces of the specimens (p < 0.05). The microhardness of the Z250 resin composite on the top surface in the preheated mode (78.1 ± 2.9) was higher than in the non-preheated mode (67.4 ± 4.0; p < 0.001). Moreover, the microhardness of the Z250 resin composite on the bottom surface in the preheated mode (71.8 ± 3.8) was higher than in the non-preheated mode (57.5 ± 5.7, p < 0.001).ConclusionsAlthough the results reported in the reviewed studies showed great variability, sufficient scientific evidence was found to support the hypothesis that preheating can improve the hardness of resin composites.

Effects of ionizing radiation on surface properties of current restorative dental materials

“…It is reasonable to assume that the decreased microhardness of resin composites at post-radiation obtained previously [20], different from the present investigation, may be attributed to the lower percentage of crosslinker monomers in the materials tested. From a clinical point of view, it is supposed that Eura Enamel may provide increased clinical longevity of tooth restorations in individuals undergoing head and neck radiotherapy, once microhardness is related to the material's strength [43].…”

Comparison between bond strength of lithium disilicate with preheated composite, flowable composite and resin cement

“…Accordingly, the free volume within the polymer network, solvent uptake and material degradation in the oral environment is reduced (18) . viscous composite has higher filler content than flowable composite that makes it better in mechanical properties, wear resistance, higher hardness and lesser in polymerization shrinkage (7)(8)(9)(10) . In addition, viscous composite contains high molecular weight monomers that increases the conversion degree and decrease polymerization shrinkage (19,20) .…”

“…Islam Gamal Shahin * , Cherif Mohsen ** and Hisham Katamish *** ABSTRACT shrinkage and raised mechanical properties (7)(8)(9)(10) . The drawback of using viscous composite as a cement is its high viscosity and low adaptation.…”

Two-year clinical performance and marginal integrity evaluation of high C-factor occlusal cavities restored with preheated Bulk-Fill, SonicFill and incremental fill composite resin

“…Heating the resin composites preceding the placement of composite and directly lightcuring rises the degree of monomer conversion rate and accordingly curing time will be reduced. Enhancement of the degree of polymerization of composite resin enhances its mechanical properties and increases its wear resistance [75] .…”