Author's response.

Abstract

We appreciate your encouraging comments and value your observations. We agree that the application of an acid etchant can affect the surface roughness of enamel and micromechanical retention of an orthodontic adhesive. However, it is important to consider that in our study, all brackets attached to the experimental samples, which included brackets bonded with conventional orthodontic adhesive and adhesive incorporated with benzalkonium chloride (BAC), were debonded. To rebond the brackets, the etchant was applied to all experimental samples the same number of times, with the same technique, and the same etchant. Therefore, etchant application per se, whether it was done once or multiple times on the same specimen, was not considered to be a confounding variable and could not have altered the results of the study. The delimitation of the surface area of each sample in our study was determined with the use of the Python programming language and the Opencv library. In preparation, the maxillary bone was colored with black permanent marker to isolate the molars in the photographs and mounted on a labeled black square background over 1-mm gridlines. It was ensured that the distance and angle between the camera lens and the tooth surfaces were the same for all subjects. Binary thresholding was used to segment the other areas from the teeth. Any pixel with a hue >40 was considered to be background, with everything else retained. Connected components analysis was performed to group neighboring nonblack pixels for segmentation from the background. The largest groups from the results of components analysis underwent another thresholding to segment the outline of the tooth. Flood-fill algorithm was applied to the segmented outline to produce a mask corresponding to the tooth areas. In our article, we also included in detail how the demineralized areas on the teeth were determined. The pixels with hue ε [0,11], saturation ε [65,255], and value ε [180,250] were considered to be demineralized areas. Pixel values from 200 to 255 were simplified and converted to white, and those with pixel values from 0 to 199 were converted to black. The conversion of an image to black and white automatically removed noise or the unwanted information in a digital image. This transformation converted the images to measurable binary form which can be further enhanced to create more solid lines. Binarization plays an important part in improving, recognizing, and measuring images.1Firdousi R. Parveen S. Local thresholding technologies in image binarization.Int J Eng Comput Sci. 2014; 3: 40-62Google Scholar, 2Boyat A. Joshi B. A review paper: noise models in digital image processing.Signal Image Process. 2015; 6: 63-75Google Scholar, 3Singh T. Roy S. Singh O. Sinam T. Singh K. A new local adaptive thresholding technique in binarization.Int J Comput Sci Issues. 2011; 8: 271-277Google Scholar The estimated pixels per 1 mm2 in the data set, given the parameters of the camera and the setting of the gathering site, was 2450. This value was used to calculate the over-all surface area of the teeth, the demineralized pink areas, and the white or sound areas. The percentage of enamel demineralization was computed by dividing the surface area of the entire maxillary molars and then multiplying the quotient by 100. We think that color-based image analysis can be more objective, scientific, and reliable in measuring demineralized areas after murexide analysis than scoring the demineralized areas subjectively, as was done in previous studies.4Navia J.M. Experimental and animal husbandry procedures in rat caries research.in: Tanzer J.M. Proceedings “Symposium on animal models in cariology”. Information Retrieval, Washington, DC1981: 77-87Google Scholar, 5Dubroc G. Mayo J. Christopher A. Reduction of caries and of demineralization around orthodontic brackets: effect of a fluoride-releasing resin in the rat model.Am J Orthod Dentofacial Orthop. 1994; 106: 583-587Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar The value of procedural specificationsAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 156Issue 2PreviewSincerely we congratulate the authors for their article, “Benzalkonium chloride in an orthodontic adhesive: Its effect on rat enamel demineralization using color-based image analysis,” published in the January 2019 issue (Torres-Garcia ML, Llavore LD, Bungay A, Sarol JD Jr, Pineda RR, Penas KD. Am J Orthod Dentofacial Orthop 2019;155:88-97). It was a pleasure reading the article which examines the effect of an orthodontic bonding adhesive that contains benzalkonium chloride (BAC) which has the potential to reduce the amount and percentage of demineralization in the enamel. Full-Text PDF