Assessment of Wettability and Contact Angle of Bonding Agent with Enamel Surface Etched by Five Commercially Available Etchants: An In Vitro Study

Background. The quantity and quality of the etching pattern produced by acids play a significant role in the wettability and contact angle of the adhesive with the enamel surface in orthodontics. The better the etch pattern, the more the surface energy of the enamel, better the penetration of the adhesive, which ultimately results in better bond strength. The present study aimed to evaluate the contact angle of the bonding agent with the enamel surface etched by five commercially available etchants and check if any difference existed between the five. Materials and Methods. Twenty-five human maxillary and mandibular central incisors and premolars extracted for orthodontic or dental purposes were used in this study as samples. The teeth were allocated into five groups based upon the etchant used to etch the enamel surface. After the samples were etched, a hard tissue microtome was used to create thin slices of the enamel surface. The samples were then exposed to bonding agent Ormco Enlight. The bonding agent was released in the form of droplets onto the enamel slices mounted on a contact angle goniometer. The contact angle values were tabulated, and statistical analysis using the one-way ANOVA test was carried out. Results. The contact angle measurements of the etchant group, DPI, were the lowest, while D-tech has the highest contact angle values. However, statistical analysis revealed no statistically significant difference between the contact angle measurements of the five groups included in the study. Conclusion. No statistically significant difference existed between the five etchant groups included in the study. However, commercially available etchant DPI showed lesser contact angle and thus better wettability in comparison to other groups. Further elemental analysis and surface analysis are required to validate these results.

One-Time Multi-Depth Silicon Etching Method Based on SiO2 Masking Layer

In order to improve the possibility of successful bonding and performance of structures, the new method for multi-depth silicon etching is required. This paper aims to design and create a new method for one-time multi-depth silicon etching in manufacturing complex structures based on SiO2 masking layer. The core idea of this method is that: Firstly, all patterns are transferred into photo resist through photo etching; Then etch pattern will be transferred in the SiO2 masking layer by multi-time shallow etching with different time etching control; Finally, patterns will be transferred to the silicon wafer with uniform ratio based on the measured etching selectivity of SiO2-Si with one time. In the experiments, the process is completed in the silicon wafer with SiO2 masking layer whose thickness is elaborately designed. Firstly, the etching rate of SiO2 and the etching selectivity of SiO2-Si were measured accurately. Secondly, the shallow structure based on the designed structure, the etching rate of SiO2 and the etching selectivity of SiO2-Si is etched on the SiO2masking layer. The second step forms different thickness version of SiO2 masking layer. At last, the SiO2 masking layer is etched until final structure and consequently different depth of groove accomplish due to various thickness of SiO2 etched by previous step. The experimental results indicated that the new methods has at least three advantages compared to traditional method: That is faster efficiency, higher cleanness and more complex structure. Fast work efficiency owes to only SF6 etching rather than two gases of SF6 and C4F8 to reduce half of time. Also high cleanness comes from being not exposed to air and researchers directly. The largest benefit of new method may be that can create more complex structure for higher required machine design and for higher mechanical function. It is because that normal etching method could only build few different depth of grooves due to multi-process limitation and contrary to normal one, new method can create more different depth of groove. And more different depth of groove means that more complex structure can be designed.

Effects of a Self-Etching Primer and 37% Phosphoric Acid Etching on Enamel: A Scanning Electron Microscopic Study

ABSTRACT Objective The purpose of this study was to compare the etching effects of a self-etching primer with 37% phosphoric acid on enamel by using a scanning electron microscope. Bond strength and the site of bond failure were also determined for brackets bonded using SEP and 37% phosphoric acid. Materials and methods A total of 60 maxillary premolar teeth were used for this study and they were divided into four groups. First two groups were used for studying the different types of etch patterns obtained and the next two groups were used to test the bond strength with the help of Universal testing machine. After debonding, the amount of residual adhesive was assessed according to adhesive remnant index using a stereomicroscope. Results The majority of etch patterns obtained in the 37% phosphoric acid group were type II, whereas in the SEP group, type IV pattern was more common. There was no statistically significant difference between mean bond strengths obtained with the SEP group and the phosphoric acid group. Use of SEP results in less amount of residual adhesive on tooth surface after debonding. Conclusion SEP produces more conservative etch pattern compared to 37% phosphoric acid. Use of SEP for bonding provides similar and clinically acceptable bond strength compared to use of 37% phosphoric acid etching technique and requires less clean-up procedures hence, reduces enamel loss. Clinical significance Use of 37% phosphoric acid for orthodontic bonding yields high bond strength but, causes enamel loss during both etching and debonding. SEPs not only provide adequate bond strength with a more conservative etch pattern but also enable easy debonding, thereby reducing the enamel damage. How to cite this article Nanjannawar LG, Nanjannawar GS. Effects of A Self-Etching Primer and 37% Phosphoric Acid Etching on Enamel: A Scanning Electron Microscopic Study. J Contemp Dent Pract 2012;13(3):280-284.

Atomic Layer Deposition and Vapor Deposited SAMS in a CrossBeam FIB-SEM Platform: A Path To Advanced Materials Synthesis

Nanopatterning refers to the fabrication of nanometer-scale structures, meaning patterns with at least one lateral dimension between the size of an individual atom and approximately 100 nm. Direct Write or Maskless Lithography as discussed in this article refers to the use of a focused beam, either an ion beam or an electron beam, to create a patterned image directly into (etch), or on top of (deposition), the target material. Both electron beams and ion beams can be used together with gas injection technology to deposit three dimensional structures on the nanometer scale through the process of either electron beam assisted or ion beam assisted chemical vapor deposition (CVD). The deposition occurs only in the vicinity where the electron beam or ion beam is being scanned. Therefore, the deposit will follow the form of the scanned beam in two dimensions. This approach can be applied to produce three-dimensional objects by successively layering upon the two-dimensional pattern. In the case of ion beams in particular, the direct write process can also produce an etch pattern on the nanometer scale as the ion beam physically mills away the material via ion bombardment. This process can also be chemically enhanced for certain materials such as simultaneous use of water to selectively etch carbon.

Surface Analysis of Etched Molar Enamel by Gas Adsorption

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson’s Correlation Coefficient showed a lack of relationship between etch pattern and total surface area.