To adapt interns to the stage of clinic dentist as soon as possible and to increase the efficiency of internship,we have applied problem-based learning(PBL) model to the clinic practice of prosthodontics in the students of Grades 2002 and 2003.Such a teaching reform cultivates their interests in autonomous study,increases their confidence,improves the relationship with patients and trains their re-learning ability.

BACKGROUND: BACKGROUND: Studies have found that surface treatment agents containing 10-methacryloyloxy decyl dihydrogen phosphate may be chemical y bonded to the oxide on the surface of zirconia, thereby notably improving the bonding performance of zirconia. OBJECTIVE: To study the effects of Mondbond N and Single bond Universal Adhesive on microtensile bond strength between zirconia and composite resin. METHODS: Sixty pieces of zirconia were randomized into three groups: in group 1, conventional Bis-GMA resin cement was used to bond zironia and composite resin; in group 2, conventional Bis-GMA resin cement was used to bond zironia and composite resin fol owing Mondbond N treatment; in group 3, conventional Bis-GMA resin cement was used to bond zironia and composite resin fol owing surface treatment with Single Bond Universal Adhesive containing 10-methacryloyloxy decyl dihydrogen phosphate. Microtensile bond strength and microstructure on the bonding interface were compared among three groups. RESULTS AND CONCLUSION: (1) Microtensile bond strength was significantly higher in the groups 2, 3 than group 1 (P < 0.05), and there was no difference between the two former groups. (2) Scanning electron microscope observation of the bonding interface: before microtensile test, there were more fissures on the bonding interface of group 1; in the group 2, there were a few fissures on the bonding interface that was relatively even; in the group 3, the bonding interface was smooth and continuous with few fissures. After microtensile, cohesive failure and bonding interface failure were mainly seen in the three groups, but there was no simple interface failure in the groups 2 and 3. These findings indicate that Monobond N and Single Bond Universal Adhesive can both improve the bonding strength of zirconia with composite resin.