Microbiological and SEM-EDS Evaluation of Titanium Surfaces Exposed to Periodontal Gel: In Vitro Study

Abstract

Inflammatory diseases affecting the soft and hard tissues surrounding an implant represent a new challenge in contemporary implant dentistry. Among several methods proposed for the decontamination of titanium surfaces, the administration of topical 14% doxycycline gel seems to be a reliable option. In the present study, we evaluated the microbial effect of 14% doxycycline gel applied on titanium surfaces and exposed to human salivary microbes in anaerobic conditions. We also examined the composition of the exposed surfaces to assess the safe use of periodontal gel on titanium surfaces. Six anatase and six type 5 alloy titanium surfaces were used and divided into two groups: The test group and the positive control group. Both were cultured with human salivary samples in anaerobic conditions. On the test groups, 240 mg of periodontal gel was applied. The microbial assessment was performed with a colony-forming unit (CFU) count and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) to identify the species. The surface integrity was assessed using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS). The results demonstrated the microbial efficacy of the 14% doxycycline periodontal gel and its safe use on titanium surfaces. However, the SEM observations revealed the permanence of the gel on the titanium surfaces due to the physical composition of the gel. This permanence needs to be further investigated in vivo and a final polishing protocol on the titanium surface is recommended.

Keywords: doxycycline; implant properties; peri-implantitis.

Figure 1

Representative SEM observation of a surface from group A. The microorganisms appear morphologically healthy.

Figure 2

Representative SEM observation of a surface from group B. The magnifications show the action of the gel on the bacterial colonies.

Figure 3

Representative SEM observation of a surface from group C. The microorganisms appear morphologically healthy with a well-preserved shape.

Figure 4

Representative SEM observation of a surface from group D. The magnifications show the action of the gel on the bacterial colonies. The external appearance of microorganisms does not show a well-preserved shape of the cells.

Figure 5

SEM-energy dispersive X-ray spectrometry (EDS) representative spectrum. (a) Analysis of group E. (b) Analysis of the surfaces in group A and (c) analysis of the surfaces in group B. There is no particular difference between the groups exposed to saliva with and without the gel application. Instead, there is a small difference between the surfaces of the exposed groups and the unexposed groups. In particular, there is an increase of oxygen (O) and aluminum (Al), and a small decrease of titanium (Ti) and vanadium (V) on the surfaces of the exposed groups.

Figure 6

SEM-EDS representative spectrum. (a). Analysis of group F. (b) Analysis of the surfaces in group C and (c) analysis of the surfaces in group D. There is no particular difference between the groups exposed to saliva with and without the gel application. Instead, there is a small difference between the surfaces of the exposed groups and the unexposed groups. In particular, there is an increase of aluminum (Al) and a small decrease of titanium (Ti) and vanadium (V) on the surfaces of the exposed groups.