The microbiological effect of virgin coconut oil on the morphological and volumetric dimensional changes of 3D printed surgical guides (in vitro study)
Authors: Khalil Rania T. , Alshimy Ahmed , Elsherbini Eglal , Abd-ELLAH Mervat E. 
Published: December 2022

Abstract
Background/objectives
Disinfection of surgical guides is mandatory for intraoperative use. Virgin Coconut Oil may be a potent alternative disinfectant; however, its effect has not been fully discussed in dentistry. The objectives of this study were to compare the morphological and the volumetric dimensional changes of 3D printed surgical guides after immersion in three disinfectants: 100%Virgin Coconut Oil, 2% Glutaraldehyde, and 70% Ethyl Alcohol and to assess the antimicrobial effectiveness of the tested disinfectants.

Materials and methods
A surgical guide was designed using open platform software to print thirty guides and then cut them into two halves (N = 60). Pre-disinfection scans of the first half of the three study groups (n = 30) were performed using Cone-beam Computed Tomography, then immersed for 20 min in three disinfectants as follows: group VCO was immersed in 100% Virgin Coconut Oil, group GA was immersed in 2% Glutaraldehyde, and group EA was immersed in 70% Ethyl Alcohol. Post-disinfection scans of the first half of the three study groups (n = 30) were performed and then compared morphologically and volumetrically using an analyzing software program The second half of the three control groups (n* = 30) were soaked for 20 min in sterile distilled water as follows: group VCO*, group GA*, and group EA* for the assessment of the antimicrobial effectiveness of the three tested disinfectants.

Results
At the morphological assessment of the dimensional changes, group VCO were the most accurate with the lowest mean deviation value of 0.12 ± 0.02 mm and root mean square value of 0.12 mm, group GA and group EA were less accurate with mean deviation value of = 0.22 ± 0.05 mm and = 0.19 ± 0.03 mm and root mean square value of 0.22 and 0.20 respectively (p < 0.001). At the volumetric assessment, group VCO showed lower volumetric changes with a mean deviation value of 0.17 ± 0.10 mm, root mean square value of 0.19 mm, than group GA with mean deviation value of 0.23 ± 0.10 mm, root mean square value of 0.25 mm and group EA with mean deviation value of 0.27 ± 0.11 mm, root mean square value of 0.29 mm, however, no statistically significant differences were found between the three study groups (p = 0.10). The antimicrobial effectiveness of the three tested disinfectants showed a hundred percent (100%) reduction in the total microbial count in the first half of the three study groups treated with the three disinfectants revealing no bacterial growth, however, statistically significant differences were found between the second half of the three control and the first half of the three study groups. (p < 0.001).

Conclusions
Virgin Coconut Oil showed higher morphological dimensional accuracy of the tested surgical guides than Glutaraldehyde and Ethyl Alcohol without causing any volumetric dimensional changes in the 3D printed surgical guides after disinfection for 20 min and the antimicrobial effectiveness was the same between the three tested disinfectants without showing any microbial growth.