Fracture Resistance of Structurally Compromised Roots with Aesthetic Dowel Systems

Objectives: This study evaluated the validity of composite resin and glass ionomer cement for reinforcement of flared root canals before aesthetic dowel system application. Methods: To simulate weakness, the entire surfaces of 140 extracted human single-rooted teeth were enlarged to reduce the thickness of dentin wall to 0.5 mm. The teeth were equally divided into 7 test groups (n=20) according to the canal irrigant used: no irrigant (control), 5% hydrogen peroxide, 5% sodium hypochlorite, a combination of 5% hydrogen peroxide and sodium hypochlorite, 15% ethylenediaminotetraacetic acid (EDTA), 10% lactic acid, or 20% lactic acid. Within each group, half of treated root canals (n=10) were filled with composite resin (PermaFlo, Kerr) and the other half were filled with glass ionomer (Fuji One, GC America). A light-transmitting plastic post (Luminex, Dentatus) was used to create space for the fiber-reinforced posts (DT light post, Bisco) and (Aesthetic post, Bisco) (n=5) and to cure the restorative materials All posts were cemented with adhesive resin cement (Panavia 21, Kurrary). Compressive load was applied at 130им on lingual surface of the composite core (Corestore 2, Kerr) to obtain the fracture resistance on an Instron universal testing machine. The data were analyzed with 1-way ANOVA followed by Ryan-Einot-Gabriel-Welsch Multiple Range Test (a=.05). Results: Lactic acid solutions and EDTA created micromechanical retention in the dentin with composite resin. Moreover, a hybrid layer was detected along the dentin wall and fracture resistance was significantly higher than other groups (p<.001). Conclusions: Composite resin bonding systems are an efficient method to reinforce structurally compromised roots with a lactic acid irrigant. Moreover, aesthetics can be enhanced with aesthetic dowel rehabilitation. Supported by grant No. AT-25-93 from King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia.