Conventional, microfilled and hybrid composite resins : laboratory and clinical evaluations

Abstract: Three types of composite resins, classified as conventional, microfilled and hybrid resins were compared with respect to surface characteristics, effect on the gingival margin, marginal adaptation and clinical durability in anterior cavities.The surface characteristics were studied in in vitro systems by means of scanning electron microscopy. Fillings prepared in vivo were evaluated regarding surface characteristics, marginal conditions, color stability and the effect on the develop­ment of gingivitis and caries.Microfilled resins were superior to the conventional and hybrid composites with regard to the possibility of obtaining and retaining a smooth surface. The number of porosities varied greatly between the composites investigated and could not be related to the type or curing method used in their manufacture. Marginal defects in the form of chip fractures and fractures in the resin parallel to the resin/enamel border were seen more frequently in the microfilled composite fillings than in the conventional and hybrid resins. The severity of the defects increased with time.There was a great variation in clinical behaviour within each resin group. The dif­ference in surface characteristics between the three composites did not result in clinically measurable differences in amount of plaque on and degree of gingivitis around the composite fillings neither during a period of normal home care nor during an experimental gingivitis period. Recurrent caries was the major single reason for replacement. Patients with a greater number of caries risk factors clearly showed a higher caries increment, especially around composite fillings. The short­comings of the three composite resin types indicate that no material as yet meets the demands of an all purpose material.