INVESTIGATION OF THE SEALING PROPERTIES OF ADHESIVE SYSTEMS 5 AND 7 GENERATIONS

Abstract

Composite filling materials are used as restorative materials in modern therapeutic dentistry. Composite filling materials have neither mechanical nor chemical adhesion to the tooth hard tissues. Thus, they require usage of additional materials, such as adhesive systems, in order to improve the quality of bonding. The manufacturers mention indications for usage in the instructions to the products; however their studies are protected with property rights and unavailable to wide public. Therefore, a detailed study of modern adhesive systems is important for the sense of treatment of hard tooth tissues.The purpose of the research was to determine the effectiveness of sealing property of adhesive systems of 5th and 7th generations in the restoration of pregingival tooth defects. In order to solve the set tasks, 160 teeth with wedge-shaped defects which were removed according to orthodontic and surgical indications in patients aged 20-45 years were studied. After extraction the teeth were rinsed under running water, cleaned from blood clots, stored in saline (sodium chloride 9 mg/ml) and used within a week. All teeth were divided into two groups, depending on the applied 5th and 7th generation of adhesive system. Charisma F composite material was used as a filling material in all cases in order to eliminate any difference in filling material properties. Each group was divided onto 4 subgroups, depending on the treatment tactics: 1 – non-preparatory method; 2 – grinding of walls along the perimeter of the defect; 3 – preparation, with the formation of the floor of the cavity and perpendicular pregingival wall; 4 – preparation with the formation of the floor and four walls. The micro leakage test of the adhesive systems was performed before and after the application of alternating loading. All prepared teeth, were divided into two groups for testing. Both groups of teeth were marked, 20 samples of teeth from each group were used for each testing. As soon as the filling process was completed, the prepared samples were immersed in 0.1% methylene blue indicator solution for 2 hours. Afterwards the samples were washed with water. Samples were immersed in the indicator solution vertically so that the restoration is in solution and the root of the tooth was placed above the solution level. Further, samples of the first group were splitted in sagittal dimension through the center of the filling with a diamond bur avoiding overheating. Assessment of hermeticity of the filling was performed with a 10x magnifying loupe for detection of indicator penetration of the along the walls of the cavity, using the following scale: 0 – no penetration of the dye; 1 – penetration of the dye within the enamel; 2 – penetration of the dye to the enamel-dentin junction; 3 – penetration of the dye to the floor of the cavity. For determination of the effect of variable loads on the marginal adaptation of filling (under the masticatory load), the samples of the second group were positioned vertically, fixed with a self-curing resin. An AC load of 10-25 kgf of 30 cycles/min was applied using a universal machine for mechanical testing for 10 min. Sielast K. imprint material was used as an antagonist to simulate the chewing process. The leakage assessment was performed according to the same criteria as in the first group. According to the obtained results, it can be concluded that for the restoration of wedge-shaped teeth defects it is possible to use adhesive systems of both (5th and 7th) generations. An important prerequisite for preparation of teeth should be at least grinding of the walls of the lesion, even without changing of their shape, because under the microscope you can see areas of incomplete adhesion of the material to the enamel that has been painted, in the case of a nonpreparable method of treatment of wedge-shaped defects. The 5th generation adhesive system showed slightly better results before application of the load (1 sample was painted out of 20, unlike the 7th generation adhesive system, where the dye penetration was noted in 3 samples) and after alternating loading (1 sample of the first group with adhesive was painted 5th generation out of 20, and in the second group with the 7th generation adhesive system – 2 samples). However, these results are also valid as the colour intensity and the penetration depth were the same.

Keywords

• sealing properties
• adhesive systems
• wedge-shaped defects.