The biological seal of the implant-soft tissue interface evaluated in a tissue-engineered oral mucosal model.

For dental implants, it is vital that an initial soft tissue seal is achieved as this helps to stabilize and preserve the peri-implant tissues during the restorative stages following placement. The study of the implant-soft tissue interface is usually undertaken in animal models. We have developed an in vitro three-dimensional tissue-engineered oral mucosal model (3D OMM), which lends itself to the study of the implant-soft tissue interface as it has been shown that cells from the three-dimensional OMM attach onto titanium (Ti) surfaces forming a biological seal (BS). This study compares the quality of the BS achieved using the three-dimensional OMM for four types of Ti surfaces: polished, machined, sandblasted and anodized (TiUnite). The BS was evaluated quantitatively by permeability and cell attachment tests. Tritiated water (HTO) was used as the tracing agent for the permeability test. At the end of the permeability test, the Ti discs were removed from the three-dimensional OMM and an Alamar Blue assay was used for the measurement of residual cells attached to the Ti discs. The penetration of the HTO through the BS for the four types of Ti surfaces was not significantly different, and there was no significant difference in the viability of residual cells that attached to the Ti surfaces. The BS of the tissue-engineered oral mucosa around the four types of Ti surface topographies was not significantly different.

Ultrastructural analysis of implant-soft tissue interface on a three dimensional tissue-engineered oral mucosal model.

A three dimensional tissue-engineered human oral mucosal model (3D OMM) used in the investigation of implant-soft tissue interface was recently reported. The aim of this study was to examine the ultrastructural features of soft tissue attachment to various titanium (Ti) implant surfaces based on the 3D OMM. Two techniques, that is, focus ion beam (FIB) and electropolishing techniques were used to prepare specimens for transmission electron microscopic (TEM) analysis of the interface. The 3D OM consisting of both epithelial and connective tissue layers was constructed by co-culturing human oral keratinocytes and fibroblasts onto an acellular dermis scaffold. Four types of Ti surface topographies were tested: polished, machined (turned), sandblasted, and TiUnite. The specimens were then processed for TEM examination using FIB (Ti remained) and electropolishing (Ti removed) techniques. The FIB sections showed some artifact and lack of details of ultrastructural features. In contrast, the ultrathin sections prepared from the electropolishing technique showed a residual Ti oxide layer, which preserved the details for intact ultrastructural interface analysis. There was evidence of hemidesmosome-like structures at the interface on the four types of Ti surfaces, which suggests that the tissue-engineered oral mucosa formed epithelial attachments on the Ti surfaces.

Susceptibility of Enterococcus faecalis biofilm to antibiotics and calcium hydroxide.

The purpose of this study was to investigate the antimicrobial efficacy of six groups of antibiotics and calcium hydroxide against Enterococcus faecalis biofilm in a membrane filter model. Two-day-old E. faecalis (ATCC 29212) biofilm was exposed to ampicillin, co-trimoxazole, erythr omycin, oxytetracycline, vancomycin, vancomycin followed by gentamicin, Ca(OH)(2), and phosphate-buffered saline (control). After 1 h of exposure, the antimicrobial activity was neutralized by washing each disc five times in PBS, and then the colony-forming units of the remaining viable bacteria on each disc were counted. The results revealed that only erythromycin, oxytetracycline and Ca(OH)2 showed 100% biofilm kill. An ANOVA with a Bonferroni post hoc test (P < 0.05) detected significant differences among the test agents, except in the ampicillin group versus the co-trimoxazole group. It is concluded that erythromycin, oxytetracycline and Ca(OH)2 are 100% effective in eliminating E. faecalis biofilm, whereas ampicillin, co-trimoxazole, vancomycin, and vancomycin followed by gentamicin are ineffective.