Nonsurgical cleaning potential of deep-threaded implants and titanium particle release: A novel in vitro tissue model

To measure the efficiency of three cleaning modalities on two implant designs with similar diameters but different thread depths as well as the presence of titanium particles.

Sixty dyed implants (30 × 4.8 apically tapered (ATAP) and 30 × 5.0 fully tapered (FTAP)) were fixed in plastic models. The horizontal bone defects were surrounded with porcine soft tissue. Three instrumentation modalities were used to clean for 150 s: Curette (CUR), ultrasonic scaler (US), and air powder waterjet device (APWJ) with erythritol powder. Afterward, implants were photographed and scanning electron microscopic (SEM) images were taken. Titanium in the soft tissues was quantified in dissolved samples and histologically confirmed.

For ATAP and FTAP implants, the percentage of the cleaned surface was 26.4 ± 3.0 and 17.1 ± 2.4% for CUR, 33.7 ± 3.8% and 28.1 ± 2.3% for US, and 45.5 ± 4.1% and 24.7 ± 3.8% for APWJ, respectively. SEM images showed significant implant surface changes, especially after instrumentation with CUR and US, whereas APWJ had little to no effect. Most titanium residues were found after cleaning ATAP implants with CUR (152.0 ± 75.5), followed by US (89.5 ± 73.8) and APWJ (0.3 ± 0.8). For the FTAP implants, respective values accounted for 129.5 ± 58.6 μg and 67.0 ± 14.4 μg for CUR and US, respectively. No titanium residues were detected on ATAP with APWJ.

Based on in vitro data, erythritol-powered APWJ still appears to be the most efficient and gentle cleaning method. All three instruments, however, were found to have unprocessed areas depending on different implant designs, hence, clinical relevance for non-surgical approaches remains challenging and warrants further improvement.