We appreciate the readers’ interest in our research article. They have rightfully raised a concern about the sample processing method, which we think is attributable to the lack of details of our methodology. We are glad to present a more detailed description of the methodology and an explanation to the questions raised.
The external elements (oxygen, nitrogen, calcium, phosphorus, iron, fluorine, sodium, chlorine, magnesium, cerium, and potassium) were found to be precipitated on the surface of the miniscrew implants (MSIs) that were anchored in alveolar bone; the neck part remained in contact with oral soft tissues and the head in contact with saliva, its contents, and food. In essence, implant surfaces do acquire different precipitates from contact with biologic fluids and bone. The biologic fluids that are in contact with MSIs are blood and exudates, saliva and its contents, and foods. After retrieval of the MSIs, they were gently washed to remove debris without disturbing the precipitated elements; the first objective was to study the elements on the surface layer. Although gentle washing removes loosely attached debris, heavy cleaning such as ultrasonication with a detergent would disrupt some of these elements from their sites on the implant surfaces. Debris-free regions on MSIs at the specific sites were subjected to elemental composition analysis by using x-ray microanalysis (EDX). The EDX readings were taken on the debris-free regions located with the scanning electron microscope (SEM). The data thus obtained with the EDX showed precipitated elements and not contaminated surfaces of the MSIs by organic debris. Hence, we concluded that modification of the elemental composition of the surface layer of the MSIs occurred in the mouth.
Our conclusion that “the surface elemental composition of retrieved MSIs differs from that of as-received MSIs” was based on the EDX analysis of debris-free sites on MSIs facilitated by SEM. The obvious source of the altered composition of the surface layer of MSIs is the biologic oral tissues and fluids in the oral cavity.
After we obtained the EDX analysis, these MSIs went through a second, more aggressive cycle of cleaning with ultrasonication. This step was essential to remove the adhering organic debris and precipitates, so that we could observe the entire MSI surface clearly for surface characterization under the SEM.