## 4 Discussion
In a case of ideal section thickness with fine polishing and strong (mechanical and chemical) adhesion, the microscopy evaluation of the section can be successful (Figure 9A). Figure 9D shows a scanning electron microscopy (SEM) picture that represents the separation of the section from the frosted glass slide in the continuity of the scratch. Figure 9E SEM picture shows a perforated thin bone section on a glass slide. The preparation of a section to microscopy evaluation is a multistep process. The main drawback of the undecalcified thin bone section is insufficient thinness. In our study, we made an experiment to enhance the adhesion chemically and micromechanically between the pathological grade glass and components of the titanium-containing thin bone section to reduce the thickness of the section during the thinning process. Our primary goal was to investigate and increase the adhesion between the 10-MDP containing adhesive material and glass slide by frosting and protonation of glass. The chemical enhancements were achieved by 10-MDP containing bond material application and protonation of the glass slide, the micromechanical enhancements were frosting of the glass slide. A shear force acts between the surface of the section and abrasive paper during the grinding, therefore, the shear bond strength was a suitable measurement for the investigation of experimental groups. The SBS measurements revealed that the thermoplastic adhesive had the lowest bond strength (Figure 7--Group 1). The thermoplastic adhesive is a high viscosity (6000 cps at 121 \({}^{\circ}\)C) thermo-responsive material. The penetration ability of adhesive is limited to the surface irregularities and not able to bond to a smooth glass surface that resulted above 80% adhesive failure modes at all samples (Figure 8). In most of the cases, the thermoplastic adhesive is separated from the smooth glass surface. In a small percentage, the failure modes showed cohesive fracture inside the thermoplastic layer. Due to the high viscosity of thermoplastic adhesive small air bubbles entrapped after cooling down, that can be starting points of defects in the adhesive layer. Based on our measurements it was found that frosted slide combined with 10-MDP containing adhesive (Figure 7--Group 2) gave significantly higher SBS data at bone and titanium compared to thermoplastic adhesive (Figure 7--Group 1). At epoxy adherent, the difference was not significant, but the numbers of cohesive fractures increased compared to a thermoplastic  
Figure 9: Presentation of issues of section thickness related to polishing of section. (**A**) Section with optimum thickness and optimal polishing (3\(\upmu\)m) on both sides; (**B**) section with thick thickness and one side optimal polishing; (**C**) section with thin thickness and one side optimal polishing; (**D**) scanning electron microscopy (SEM) picture of the scratched side of the section with the starting point of section separation from glass; (**E**) SEM picture of perforated section. that indicated the micromechanical retention (lower viscosity of 10-MDP containing bond), which is also supported by good wetting (Table 4). A rougher surface created by the frosting procedure (gently sandblasting) provided an increased surface area for enhanced adhesion. It is well-known that micromechanical retention is a frequently used procedure to enhance the adhesion of prosthodontic work to tooth structure [20]. The cured epoxy with an MDP containing bond material on frosted and protonated-frosted glass surface showed the same magnitude bond strength as a thermoplastic adhesive (Figure 7). EpoFix was a mixture and cured polymer of diglycidyl ether of bisphenol A (DGEBPA) prepolymer resin and triethylenettramine (TETA) hardener components. Hydroxyl groups are formed on the polymer chain at the end of crosslinking polymerization [21]. The epoxy surface has hydrophobic nature based on contact angle measurements (Table 4), but the MDP containing bond material can wet well this surface due to ethanol content (Figure 6).