Chemotherapeutic decontamination of dental implants colonized by mature multispecies oral biofilm.

AIM: No studies have tested disinfectants on mature multispecies oral biofilms on titanium substrata. The aim of this study was to investigate the efficacy of commonly used antimicrobial agents in decontamination of multispecies mature oral biofilm on sandblasted, large-grit, acid-etched (SLA) titanium implants. METHODS: SLA titanium disks were inoculated with dental plaque and cultured anaerobically for 21 days. The disks were rinsed with 0.9% NaCl, exposed for 2 min. to tetracycline paste, 1% Chlorhexidine gel (CHX), 35% phosphoric acid gel (Etch) or a novel chemical formula (0.3% cetrimide, 0.1% CHX and 0.5% EDTA) and then rinsed again with 0.9% NaCl. Bacteria were quantified from scanning electron micrographs of the implant surfaces. Living bacteria were quantified with confocal laser scanning microscopy (CLSM). RESULTS AND CONCLUSIONS: Rinsing the surfaces with 0.9% NaCl removed the majority of the biofilm. However, bacteria persisted in all specimens and none of the disinfectants was superior to the double saline rinse group. CLSM analysis showed that CHX and Etch groups had a statistically significant reduction of viable bacteria, although small. Overall the results show that many disinfection agents used in the clinic are ineffective in biofilm removal and leave live bacteria on the surface.

Intra-operative application of chlorhexidine gel reduces bacterial counts in internal implant cavity.

A prospective clinical trial was conducted to assess the bacterial-inhibitory potential of 1% chlorhexidine (CHX) gel in the internal cavity of implant screw holes, when utilized at the time of implant placement. A total of 40 Straumann (S) and Nobel Biocare (N) implants were divided into test (ST or NT; implant + CHX gel) and control (SC or NC; implant only) groups. Total numbers of colony-forming units (CFUs ml(-1) ) were assessed at a minimum of 3 months postsurgery by aerobic and anaerobic culture. A set of specimens was stained with Gram stain. The mean sample-collection time was 110 d for the test population and 98 d for the controls. The use of 1% CHX gel significantly reduced bacterial counts in both the ST and NT samples by over three logs compared with controls. No statistical differences in the numbers of CFUs ml(-1) were evident between aerobic and anaerobic cultures. Differences in the numbers of CFUs ml(-1) between ST and NT groups were not statistically significant. Microscopic analysis showed mainly Gram-positive coccoid species in most samples.

Procedure Time and Students' Perception Comparing Full Arch Digital Scans with Conventional Impressions: A Cross-Over Randomized Experimental Trial.

Methods: Ninety-six dental students each prepared tooth #36 for an all-ceramic crown on typodont models and were then randomly assigned into either group A: performed digital scan first, or Group B: performed conventional impression first. Procedure time was recorded for both. Immediately following each procedure, students indicated their perceived procedure difficulty. After exposure to both techniques, they selected their preferred one. Results: There was a statistically significant difference between the mean procedure time of both techniques (P < 0.0001), where students spent 663.76 ± 442.50 seconds to complete the conventional impression and 293.32 ± 181.49 seconds to complete the digital scan. Females were significantly faster in completing the conventional impression compared to males. On the contrary, male students were faster in digital scanning than female students. There were no carryover effects in the duration and the initially performed procedure. 76% (73 of 96) of participants preferred digital scanning with no statistical significance shown between the preferred and initially performed procedure. Participants perceived conventional impressions to be more difficult than digital scans. There was a weak positive correlation between the VAS score and the procedure time for the digital technique (R = 0.25) and a moderate positive correlation for the conventional technique (R = 0.45). Conclusions: The digital technique was preferred and perceived as easier than the conventional among undergraduate dental students with no impression-making experience, suggesting their readiness for new technology uptake. However, no significant correlation was found between the initially performed procedure and preference.