Comparison of Titanium and PEEK Medical Plastic Implant Materials for Their Bacterial Biofilm Formation Properties.

This study investigated two of the most commonly used CAD-CAM materials for patient-specific reconstruction in craniomaxillofacial surgery. The aim of this study was to access the biofilm formation of Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, and Escherichia coli on titanium and PEEK medical implant materials. Two titanium specimens (titanium grade 2 tooled with a Planmeca CAD-CAM milling device and titanium grade 5 tooled with a computer-aided design direct metal laser sintering device (CAD-DMLS)) and one PEEK specimen tooled with a Planmeca CAD-CAM milling device were studied. Bacterial adhesion on implants was evaluated in two groups (saliva-treated group and non-saliva-treated group) to imitate intraoral and extraoral surgical routes for implant placement. The PEEK medical implant material showed higher bacterial adhesion by S. aureus, S. mutans, and E. coli than titanium grade 2 and titanium grade 5, whereas E. faecalis showed higher adhesion to titanium as compared to PEEK. Saliva contamination of implants also effected bacterial attachment. Salivary coating enhanced biofilm formation by S. aureus, S. mutans, and E. faecalis. In conclusion, our findings imply that regardless of the implant material type or tooling techniques used, salivary coating plays a vital role in bacterial adhesion. In addition, the majority of the bacterial strains showed higher adhesion to PEEK than titanium.

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro.

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3× with 1× PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.

Intrathecal atipamezole augments the antinociceptive effect of morphine in rats.

BACKGROUND: Opioid analgesics are effective in the treatment of chronic pain, but they have serious adverse effects such as development of tolerance and dependence. Adrenergic α(2) agonists and µ-opioid receptor agonists show synergistic potentiation and cross-tolerance in spinal analgesia, whereas α(2)-adrenergic antagonists have shown pronociceptive effects. However, at ultralow doses, spinal α(2)-adrenergic antagonists have been reported to paradoxically enhance opioid antinociception. New data have suggested a functional µ-opioid-α(2)-adrenoceptor complex, which may help in interpreting the paradoxical effect of the α(2)-adrenergic antagonists. In the present study we assessed the effects of low doses of atipamezole, a nonselective α(2)-adrenergic antagonist, on both systemic and spinal morphine antinociception and tolerance. METHODS: Antinociception was assessed in male Sprague-Dawley rats using hotplate, tail-flick, and paw pressure tests. Spinal or systemic opioid tolerance was induced for 4 days. The effects of both intrathecal and subcutaneous atipamezole on acute morphine-induced antinociception and established morphine tolerance were studied. RESULTS: Systemic or spinal atipamezole itself did not produce antinociception at the doses studied (subcutaneous 0.03, 0.3, 3 µg/kg or intrathecal 0.1, 1, 10 ng). The combined administration of spinal morphine and 1 ng of atipamezole increased the antinociceptive effect of acute spinal morphine 30 minutes after the administration of test drugs in the tail-flick test. Furthermore, 10 ng of intrathecal atipamezole attenuated established morphine tolerance 30 minutes after the administration of test drugs in the tail-flick test. However, subcutaneous atipamezole had no significant effect on systemic morphine antinociception, and it did not attenuate morphine tolerance. CONCLUSIONS: Spinal coadministration of low doses of atipamezole augmented the antinociceptive effect of morphine in naïve and tolerant rats. Heterodimerization of µ-opioid- and α(2A)-adrenoceptors with consequent changes in function and interaction could explain these results. This also suggests an interesting explanation for the variability in opioid response and tolerance in patients experiencing stress or having an increased noradrenergic tone due to other causes, e.g., drugs.

Peri-implant tissue response to TiO2 surface modified implants.

OBJECTIVES: The objective of this study was to evaluate peri-implant soft tissue attachment and alveolar bone height on nanoporous TiO(2) thin film on commercial titanium dental implants compared with unmodified standard implants. MATERIAL AND METHODS: In six adult beagle dogs, the mandibular premolars P2-P4 were extracted bilaterally. Sol-gel-derived nanoporous TiO(2) thin film was produced on smooth coronal part of standard ITI Straumann implants (4.1 mm x 8.0 mm) by dip coating method. After 3 months healing period of the extraction sockets modified (n=24) and unmodified (n=11) control implants were placed bilaterally. The animals were killed after 8 weeks and the samples were retrieved and processed for histologic/histomorfometric and TEM/SEM evaluations. RESULTS: Histological examination showed mild or absent inflammatory reaction in peri-implant connective tissues around the surface modified implants. Further, junctional epithelium (JE)/connective tissue (CT) appeared to be in immediate contact with the experimental implants. Of the experimental implants, 22% were judged to be detached from the implant surface while 45% of the untreated control implants were detached. Dense plaques of hemidesmosomes were found in TEM evaluation of the JE cell membrane facing the surface-treated implants. In the histomorfometric analysis, the distance between the implant margin and alveolar bone crest was significantly shorter in surface-treated implants than in the control implants (P<0.02). CONCLUSION: Nanoporous sol-gel-derived TiO(2) thin film on ITI Straumann dental implants improved soft tissue attachment in vivo.