ASSESSMENT OF SHEAR BOND STRENGTH OF RESTORATIVE MATERIALS IN VARIOUS DEPTH OF HARD DENTAL TISSUE PREPARATION IN FRONT TEETH

Abstract

In modern dentistry, there are two different approaches to the restoration of anatomy and aesthetics of anterior teeth. The most common is the option of direct restoration with using composite resin materials. The second option is the restoration with using ceramic materials that is carried out through the cooperation of the dentists and the dental laboratory technicians, or, alternatively, with various CAD-CAM systems directly at the dental office. This experiment was carried out by using teeth (premolars, incisors) without significant loss of hard dental tissues. Teeth with abrasion (all except 1st degree) were excluded from the test group. Within the framework of the planned study, the selected extracted teeth were prepared (a certain volume of hard tissues was removed from the vestibular side (a subgroup of the teeth prepared within in the enamel layer, and a subgroup of teeth with the exposed dentine). A total of 40 teeth were prepared (20 teeth with the exposed dentine, 20 with the enamel preparation). The tests were carried out by using a universal testing machine AUTOGRAPH AGS-J. A sample with a tooth was placed at the top of the device then the second part of the sample containing the plate of the material (composite or ceramic), was covered with the second part of the device to be tested, and neatly, trying to avoid applying tension to the adhesive butt joints, and then fastened to the lower clamping device of the tension testing machine. We created the shear forces before the sample was destroyed, paying attention to the character of adhesion line oddments. The results of the experiment have demonstrated that the most optimal shear strength is found out in the complex of hard tooth tissues and ceramic materials IPS Empress Aesthetic and EX3, in the teeth prepared within the tooth enamel layer. When using composite resin, the values studied are lower by 11,4% and 18,1%, (application of adhesion systems of 5th and 7th generations, respectively). In the cases when dentin is exposed, the shear strength decreases by 19,5% when using ceramics modified by leucite glass, by 17,3% in the case of application of feldspar ceramics, and by 8,4% and 13,2% for composite resin restoration when using adhesive systems of 5th and 7Ith generations respectively.