Effect of Metallic Particles on the Progression of Peri-Implantitis

Concentration of metallic elements (Ti, Al, V, Mo and Cr) in tissue samples (ppb).

The concentrations of titanium (Ti), aluminium (Al), vanadium (V), molybdenum (Mo), and chromium (Cr) will be quantified separately in healthy gingival tissue and peri-implant granulation tissue using inductively coupled plasma triple quadrupole mass spectrometry (ICP-TQ-MS). The concentration of each metallic element will be reported in parts per billion (ppb) and compared between the active control and peri-implantitis groups. Unit of Measure: Parts per billion (ppb).

Microbial species richness and evenness within each sample (alpha diversity).

Alpha diversity of the submucosal microbiome will be assessed in biofilm samples collected from the peri-implant site with the greatest probing depth in participants with peri-implantitis. Bacterial DNA will be extracted and the microbiome characterised by 16S ribosomal RNA gene sequencing. Alpha diversity will describe microbial richness, defined as the number of microbial taxa detected within each sample, and evenness, defined as how uniformly their relative abundances are distributed. Results will be reported as alpha-diversity index values.

Microbial composition between samples from different clinical conditions (beta diversity).

Beta diversity of the submucosal microbiome will be assessed in biofilm samples collected from participants with peri-implantitis. Bacterial DNA will be extracted and the microbiome characterised by 16S ribosomal RNA gene sequencing. Beta diversity will quantify the degree of similarity or dissimilarity in the identity and relative abundance of microbial taxa between samples. These comparisons will be used to evaluate whether microbial community composition varies according to metallic particle concentration and the clinical characteristics of the sampled peri-implant sites. Results will be reported as beta-diversity distance values.

Percentage of TiO₂ Nanoparticles in Each Morphological Category

Titanium dioxide (TiO₂) nanoparticles will be evaluated in healthy gingival tissue from the active control group and peri-implant granulation tissue from the peri-implantitis group. High-resolution transmission electron microscopy (TEM) will be used to visualise the particles, and energy-dispersive X-ray spectroscopy (EDS/EDX) will confirm their elemental composition. Nanoparticles will be classified according to their observed shape and structural features. The percentage of identified TiO₂ nanoparticles in each morphological category will be reported for each sample. Unit of measure: %.

Mean Diameter of TiO₂ Nanoparticles

Titanium dioxide (TiO₂) nanoparticles will be evaluated in healthy gingival tissue from the active control group and peri-implant granulation tissue from the peri-implantitis group. High-resolution transmission electron microscopy (TEM) will be used to visualise the particles, and energy-dispersive X-ray spectroscopy (EDS/EDX) will confirm their elemental composition. Particle diameters will be measured using ImageJ image-analysis software, and the mean diameter of the identified TiO₂ nanoparticles in each sample will be reported in nanometres (Unit of Measure: nm).

Presence of Plaque at the Selected Implant

Plaque will be clinically assessed at six sites around the selected implant in participants with peri-implantitis. At each peri-implant site, plaque will be recorded dichotomously as present or absent. Results will be reported as the presence or absence of plaque at each of the six assessed sites.

Probing Depth (PPD, mm)

Depth of peri-implant sulcus measured at six sites per implant using standardized probing force (20-25 g). Unit of Measure: millimeters (mm)

Bleeding and/or Suppuration on Probing (BoP/SoP)

Presence of bleeding and/or suppuration elicited within 30 seconds after gentle probing at six sites per implant using a standardized periodontal probe. Unit of Measure: Categorical (Present/Absent)

Radiographic Marginal Bone Loss (mm)

Radiographic marginal bone level measured in millimeters as the distance from the implant reference point designed to be in intimate contact with the bone to the most coronal bone-to-implant contact on standardized periapical radiographs. Unit of Measure: Millimeters (mm)