The aim of this study was to evaluate cytotoxicity of direct pulp capping materials such as Dycal, Life, ProRoot MTA, and Super-Bond C&B on L929 fibroblasts. Freshly mixed or set materials were prepared and eluted by incubation with cell culture medium for working time period (fresh) or for 6 hours (set). The cells were exposed to media containing elutes for 24 hours, after which the cell survival was evaluated by MTS assays. In freshly mixed materials, average ± standard deviation % cell viabilities were 40.2 ± 14.0%, 43.7 ± 16.0%, 72.9 ± 12.7%, and 66.0 ± 13.6% for Dycal, Life, ProRoot MTA, and Super-Bond C&B, respectively. There was no statistical difference in cell viabilities among material groups, whereas in set materials, the cell viabilities were 48.7 ± 14.8%, 37.2 ± 10.6%, 46.7 ± 15.2%, and 100 ± 21.9% for Dycal, Life, ProRoot MTA, and Super-Bond C&B, respectively. Super-Bond C&B showed more cell viabilities than the other three material groups . The four vital pulp therapy materials had similar cytotoxicity when the materials were fresh. Super-Bond C&B was less cytotoxic than Dycal, Life, and ProRoot MTA after the materials were set, which suggests the use of SB-C&B in future in vivo clinical investigations. 1. Introduction Direct pulp capping is a treatment for exposed vital pulp, which uses a dental material to facilitate both the formation of reparative dentin from odontoblasts [1] and the maintenance of vital pulp [2]. These materials include calcium hydroxide or calcium hydroxide-based cements such as Dycal and Life [3, 4], mineral trioxide aggregate (MTA; ProRoot MTA) [5], and adhesive resins [6]. Selection of pulp capping materials is important to ensure dental pulp cell vitality. Historically, Hermann [7] discovered that calcium hydroxide is effective in repairing a pulp exposure site. Calcium hydroxide possesses antibacterial properties and promotes pulp tissue repair [8]. Thus, it is considered the “gold standard” for direct pulp capping, and it has a long record of clinical success [9]. MTA was developed in 1993 and has been successfully used for pulp capping [10]. When MTA powder is mixed with water, its calcium oxide component reacts with the water and forms calcium hydroxide. Thus, MTA slowly releases calcium hydroxide while setting [11]. In addition, adhesive systems have also been suggested for use as direct pulp capping materials [12]. However, it has been believed that resin systems are inferior to calcium hydroxide-based cements, including MTA [13]. The exception would be a methyl methacrylate-/tributylborane- (MMA/TBB-)
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