Poster Presentation

Time domain analysis of fracture of composite-tooth interface using acoustic emission technique

Nak-Yeon Cho. Clinical Professor

Seoul National University Gwanak Dental Hospital

Aim : To evaluate the interfacial debonding behaviors of tooth-composite interface using an acoustic emission (AE) technique and to relate it to the polymerization shrinkage kinetics of composites.

Materials and methods: An AE system was manufactured to detect the acoustic signals which were generated by the debonding at the tooth-composite interface during composite restoration. A class I cavity was prepared on the 14 extracted human premolars and divided into two groups. The prepared teeth in each group were restored with either a methacrylate based Z250 (3M ESPE) composite or a silorane based P90 (3M ESPE) composite. AE signals were measured as a function of time for 4000 s after the initiation of light curing. The polymerization shrinkage and peak shrinkage rate of two composites was measured.


Results :

The mean of the total number of AE events for P90 was lower than that of Z250. AE in Z250 group was detected right after the beginning of light curing, while AE was first initiated 40 s after light exposure in P90.


Group Mean AE Events Number Total Cumulative AE Events Number
Z250_SBMP 3.86 20
P90 1.86 10





Shrinkage Rate





Z250 2.16 0.404 1.41
P90 1.34 0.247 3.21


Conclusions: The lower the shrinkage (rate) and slower polymerization reaction of composites resulted in the lower AE events number. The AE is an effective technique to monitor the debonding kinetics at tooth-composite interface during the composite restoration in real time.