Tensile Testing of Three Self-Etch Cements with Titanium Paraposts

Objectives:  To evaluate tensile strengths of three different self-etching cements in comparison to glass ionomer cements used with Titanium paraposts.

Methods: Sixty extracted single-rooted teeth (premolars and anterior teeth) were collected and temporarily stored in 5% sodium azide solution for 24 hours.  The teeth were embedded in methyl-methacrylate and the anatomical crowns were removed to a level of 1mm above the CEJ.  Teeth were randomly divided into four groups of fifteen: 

Group 1 (control group) = GC Fuji Plus

Group 2 = Kerr MaxCem

Group 3 = 3M RelyX UniCem

Group 4 = Heraeus ICem. 

The root canals of each sample was debrided with 17% EDTA and 5.25% sodium hypochlorite.  The teeth were prepared for a #3 titanium parapost  (Coltene Whaledent) and cemented (according to each group's manufacturer's instructions) to within 4mm of the apex for each tooth (average of 11.5mm embedment).  All samples were thermocycled for 300 cycles between 5°C and 55°C with a dwell of 30 seconds.  Tensile force testing on each specimen was applied with an instron machine (Model 4202), using a 2.0mm/min crosshead speed until the posts were debonded from each tooth.   

Results: 

	Group 1	Group 2	Group 3	Group 4
Avg Tensile Force	184.8	111.1	230.9	249.3

A one-way ANOVA analysis showed that Group 4 had the highest average tensile strength, resulting in a statistically significant difference when compared to Group 1 and 2 (p=0.009 and p=0.000).  However, Group 3 and 4 did not have a statistically significant difference (p=0.123).  Group 2 had the lowest tensile strengths as compared to Groups 1, 3, and 4 showing statistically significant differences with all other groups (p=0.002 and p=0.000).

Conclusions: Overall, self-etching cements appeared to have clinical relevance for the use of cementing titanium parapost systems.  However, further testing of these newer cements is needed.                          Sponsored in part by Heraeus.