EFFECT OF THREE DIFFERENT SURFACE TREATMENT PROTOCOLS ON MICROMORPHOLOGY AND BOND STRENGTH OF TWO TYPES OF REPAIRED COMPOSITE RESTORATIONS (IN VITRO STUDY)

Azheen Mohammed HamaXareeb a and Bestoon Mohammed Faraj b


Sulaimani Directorate of Health, Kurdistan region, Iraq.
b Conservative Department, College of Dentistry, University of Sulaimani, Kurdistan Region, Iraq. 
 
 
Submitted: 25/3/2019; Accepted: 29/10/2019; Published: 21/12/2019

ABSTRACT


Background 

Repair bond strength of different composite resins has been assessed in the literature. Clinical findings on the efficacy of available surface treatment protocols are debated. 


Objectives

This in vitro study was conducted to evaluate the effect of three different surface treatment protocols on the bond strength of microhybrid and nanohybrid composite resins.


Materials and Methods

Sixty cured composite specimens divided equally into 2 groups, microhybrid and nanohybrid composite resins. Each group divided equally into 3 subgroups specific to surface treatment protocols; Group A-(Application by erbium YAG Laser), Group B-(Diamond bur abrading followed by 35% phosphoric acid etching), and Group C-(9.5% Hydrofluoric acid etching and primer bonding). All the specimens were stored for 1 week in distilled water at 37°C using an incubator. After this period they were subjected to 500 thermocycles between 5°C and 55°C, with 30s dwell time. Surface micromorphology of the above composite resins was evaluated after surface treatment by using a scanning electron microscope. Composite blocks were repaired with the same composite type but of a different color. Then micro shear bond strength findings analyzed statistically.


Results

Microhybrid composite showed significantly higher bond strength. Hydrofluoric acid etching combined with primer bonding was significantly superior to the other two methods.


Conclusions

Microhybrid composite showed a better repair bond strength compared with nanohybrid composite. Among the assessed preparation protocols, group C showed the higher bond strength, followed by group B and group A showed the lowest repair bond strength. 


KEYWORDS

Composite Resin, Treatment Protocols, Micromorphology, Bond Strength.