The scanning electron microscopy of hard dental tissues prepared using steel and diamond burs showed surfaces covered with a thick smear layer that may be relevant to the subsequent bonding of adhesive restorative materials to the prepared cavity. In preparing the surface using a turbine with diamond burs the smear layer was thinner and part of the dentinal tubules orifices were open in the area of water turbulence. SEM analysis of hard dental tissues prepared with the help of colourless Carisolv gel showed a rough, retentive surface, some of the dentinal tubule lumens obstructed by denaturated collagen and surface contaminants. The teeth surfaces prepared with Er:YAG laser Lite Touch (Syneron) remained without smear layer and clearly exposed dentinal tubules orifices. The surfaces were highly retentive.

The dentin surface, prepared with Er:YAG laser demonstrates a very good adaptation of the three tested pulp-capping materials.

Purpose:The preparation of hard dental tissues for veneers is a very technically demanding process, where minimal invasive manner matters. The optical magnification offers higher resolution; brighter and enlarged threedimensional images which improve the precision and the working posture. The study is evaluating the impact of optical magnification on the precision of tooth preparation under simulated clinical conditions in à digital manner.Materials and Methods: For the test specimens, 60 plastic upper incisors are divided into 3 groups (n= 20): 1st group -teeth prepared with a naked human eye.; 2nd group -teeth prepared using compound loups x2,5 magnification; 3rd -teeth prepared using an operating microscope under x6.0 magnification. A laboratory scanning device is used to scan the teeth both before and after the preparation phase. Computer-aided design software is used to overlay the outlines of the teeth it all groups. A sagittal plane is constructed throughout the digital teeth images, and measurements of cut hard dental tissues are done in order to evaluate the accurateness of tooth preparation according to the depth of preparation.Results: There is a statistical difference between the pre-established volume of preparation and the actual cut of hard dentinal tissues no matter the magnification. There is a statistically significant difference between the depth of preparation in naked eye cases and the magnification cases.Conclusions: The quantity of cut tissues it more than the preestablished parameters which may affect the quality of the adhesive bond and it is controversy with the minimally invasive approach. The preparation under magnification is much more precise when compared to a naked eye.

Introduction: One method to evaluate the clinical success of cemented restorations is measuring the marginal adaptation. There is a correlation between the fitting of the restoration and problems caused by clinically undetectable passage of bacteria between the tooth structure and the veneer. Aim: To evaluate in comparison the marginal adaptation of veneers produced via CAD/CAM and press technique. Materials and methods: 32 extracted incisors are divided into two equal-number groups (n=16) according to the production technique – CAD/CAM zirconium veneers and press-ceramic veneers. Cut sections are examined under a SEM magnification. Marginal accuracy is measured as the distance between the finish line of the tooth and the margin of the veneer at eight fixed locations. Results: The mean values of marginal gap of group 1 are: external adaptation – 79.88±3.71 µm; internal adaptation – 79.14±15.70 µm; cervical adaptation – 82.39±28.55 µm; incisal adaptation – 86.85±21.72 µm. The mean values of marginal gap of group 2 are: external adaptation – 100.31±2.16 µm; for internal adaptation – 101.01±12.51 µm; cervical adaptation – 91.55±3.31 µm; incisal adaptation – 93.76±2.54 µm. Conclusions: Veneers produced via CAD/CAM technology have better fit at the external and internal marginal wall. There is no statistically significant difference between the gaps at the cervical and the incisal areas.

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