# Titanium Perimplant Tissue Alterations: A Prospective Cohort Plate Retrieval Study
## 4 Discussion  
This is the first study that uses ICP-OES to analyze soft tissue surrounding titanium plates retrieved from orthognathic and trauma patients. Our study has demonstrated with another investigation method that titanium traces can be found adjacent to the titanium plates. Being the first study of our knowledge using ICP-OES to assess titanium in soft tissue, we cannot compare the results with similar papers. The value of 1.06 ppm cannot be compared to another value and further studies are necessary to validate this method and to cross-check the results. Histological studies have shown titanium particles in the soft tissue adjacent to plates without any inflammatory response [8]. Another study by [PERSON] et al. showed similar results after retrieving the soft tissue around titanium miniplates and analyzing them with histology, Energy-dispersive X-ray spectroscopy (EDXA) and Scanning electron microscope (SEM) [9]. No inflammatory response was also found. Another paper found dense particles in the tissue surrounding the dental implant at 6 months [22]. It is believed that electrochemical and mechanical processes such as stress corrosion cracking, corrosion fatigue and fretting corrosion may interact and cause structural failure and accelerate the release of metal particles and ions [23,24]. In an in vitro model using New Zealand rabbits, titanium implants were placed in the tibia. Traces of titanium have been found in remote organs, but no toxic levels were detected and the concentration was below the normal intake average [25]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Patient/Surgical Site** & \
\begin{tabular}{c} **Tissue Sample** \\ **Number** \\ \end{tabular} &
\begin{tabular}{c} **Titanium Particles** \\ **(ppm)** \\ \end{tabular} & **Complications** \\ \hline
1—Orthognathic & 1 & 1.16 ppm & None \\  & 2 & 1.18 ppm & None \\
2—Orthognathic & 3 & 0.95 ppm & None \\  & 4 & 0.82 ppm & None \\
3—Orthognathic & 5 & 0.68 ppm & None \\  & 6 & 1.23 ppm & None \\
4—Orthognathic & 7 & 1.19 ppm & None \\  & 8 & 1.09 ppm & None \\
5—Fracture site & 9 & 1.2 ppm & None \\  & 10 & 0.99 ppm & None \\
6—Fracture site & 11 & 1.27 ppm & None \\  & 12 & 1.3 ppm & None \\
7—Orthognathic & 13 & 1.21 ppm & None \\  & 14 & 0.87 ppm & None \\
8—Fracture site & 15 & 1.17 ppm & None \\  & 16 & 1.26 ppm & None \\
9—Fracture site & 17 & 0.67 ppm & None \\  & 18 & 0.92 ppm & None \\
10—Orthognathic & 19 & 0.76 ppm & None \\  & 20 & 1.28 ppm & None \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summarized results of the soft tissue samples retrieved adjacent to titanium plates. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Average** & **Standard Deviation** & **Min** & **Max** \\ \hline All sites & 1.06 ppm & 0.209 ppm & 0.67 ppm & 1.30 ppm \\ Orthognathic & 1.03 ppm & 0.207 ppm & 0.68 ppm & 1.28 ppm \\ Fracture site & 1.09 ppm & 0.219 ppm & 0.67 ppm & 1.30 ppm \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Statistical analysis of the results of the soft tissue surrounding the titanium plates. Another study concerning the immuno-inflammatory response adjacent to titanium plates after mandibular fractures by [PERSON] el al. [26] using histology, immunohistochemistry, immuno-positron microscopy and EDX demonstrates the persistence of mild to moderate inflammation and fibrous tissue adjacent to the Ti plates. The design of this research paper did not use consecutive patients, and this may represent a risk of bias regarding patients selection. This may explain the lack of complications in this paper. An additional paper by [PERSON] et al. [27] studying soft tissue response after titanium plate removal after fractures and bone graft using light microscopy and transmitted electron microscopy (TEM) shows the persistence of titanium in the connective tissue. Their recommendation is to remove the titanium plates due to concern about the progression of local tissue damage.