Category: Laboratory Research
Direct and Indirect Composite Onlays on Fracture Strength of ETT
Thidarat Angwarawonga* (thidarat_ang@hotmail.com)| Patchareeporn Keatdumronga | Duangruthai Chotiwutthiphatthana
aDepartment of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand
Objective: To compare the effect of different direct and indirect composite onlay materials on the fracture load of endodontically treated teeth (ETT).
Methods: One direct composite resin ((Filtek™ Z250 (Z250)) and two indirect composite resins (SR Nexco (NC) and Ceramage (CM) were used to fabricate onlay restorations. Forty maxillary premolars were divided into five groups (n=8). Group 1 was left intact (INT; positive control). The remaining premolars received class II MOD cavity preparation and conventional root canal treatment. Group 2 was restored with temporary zinc oxide-based sealing compound and polymer-reinforced zinc oxide eugenol intermediate restorative material (IRM; negative control), whereas Groups 3-5 were prepared onlay cavities, restored with composite core build-ups (a short fiber-reinforced composite resin, EverX Posterior) and direct or indirect composite onlays. Before the fracture test, all specimens were immersed in distilled water at 37ºC for 24 hours. Each specimen was subjected to compressive load at a 45-degree angle to the long axis of a tooth with a crosshead speed of 0.5 mm/min until fracture using the universal testing machine. The fracture load was measured and statistically analyzed using One-way ANOVA and Tukey's HSD test (a=0.05).
Results: The mean of fracture load (mean±SD) was 635.63±110.54 N, 324.41±96.42 N, 554.39±112.68 N, 573.04±174.30 N, and 584.95±97.64 N for INT, IRM, Z250, NC, and CM,respectively. One-way ANOVA analysis with Tukey's HSD test showed no significant difference in the mean of fracture load among the intact teeth group and all experimental groups (p>0.05). The IRM group has the lowest fracture strength, which differed statistically from the other groups ((p<0.05).
Conclusion: Endodontically treated maxillary premolars restored with Filtek™ Z250, SR Nexco or Ceramage onlays have fracture strength comparable to intact teeth.
Funding/Conflict of Interest: This work was supported by the Faculty of Dentistry at Khon Kaen University.
Keywords: fracture strength, composite onlay, endodontically treated teeth