A degradable, poly (lactic-co-glycolic acid) (PLGA), gentamicin-loaded prophylactic coating for hydroxyapatite (HA)-coated cementless hip prostheses is developed with similar antibacterial efficacy as offered by gentamicinloaded cements for fixing traditional, cemented prostheses in bone. We describe the development pathway, from in vitro investigation of antibiotic release and antibacterial properties of this PLGA-gentamicin-HA-coating in different in vitro models to an evaluation of its efficacy in preventing implant-related infection in rabbits. Bone in-growth in the absence and presence of the coating was investigated in a canine model. The PLGAgentamicin-HA-coating showed high-burst release, with antibacterial efficacy in agar-assays completely disappearing after 4 days, minimising risk of inducing antibiotic resistance. Gentamicin-sensitive and gentamicinresistant staphylococci were killed by the antibiotic-loaded coating, in a simulated prosthesis-related interfacial gap. PLGA-gentamicin-HA-coatings prevented growth of bioluminescent staphylococci around a miniature-stem mounted in bacterially contaminated agar, as observed using bio-optical imaging. PLGA-gentamicin-HA-coated pins inserted in bacterially contaminated medullary canals in rabbits caused a statistically significant reduction in infection rates compared to HA-coated pins without gentamicin. Bone ingrowth to PLGA-gentamicin-HAcoated pins, in condylar defects of Beagle dogs was not impaired by the presence of the degradable, gentamicinloaded coating. In conclusion, the PLGA-gentamicin-HA-coating constitutes an effective strategy for infection prophylaxis in cementless prostheses.
A previously undocumented complication of root canal therapy is reported. A dilute solution of 5-10 mls sodium hypochlorite was inadvertently injected into the maxillary sinus during root canal therapy of a right upper second premolar (5). The patient developed acute, sudden, severe facial pain and swelling necessitating emergency admission to hospital and operative intervention under general anaesthesia. A diagnosis of acute chemical sinusitus was made, further management and discussion follow.
Inter-radicular placement of orthodontic miniscrews is a valuable source of anchorage in the treatment of orthodontic patients. Root perforation is a possible complication from inter-radicular placement of orthodontic miniscrews. Root perforation can be successfully treated, but may involve apical surgery.
Confocal Raman spectroscopy was undertaken to identify separate layers of PLGA and gentamicin sulfate (GS) coatings on a titanium alloy substrate for a novel drug-delivery system. Additionally, it was found that it was possible to measure the layer thickness and uniformity of the PLGA accurately by detecting intensity and wavelength changes in the vibrational bands of the copolymer bonds. Further analysis of the materials was done using FIB, SEM/EDX, and profilometry; these techniques were used to confirm the findings of the Raman data. It was determined that the substrate was extremely rough and therefore the coating was not uniform in thickness but the materials were uniformly dispersed. Most importantly, two distinct GS and PLGA layers were present.
Both primary upper second molars were extracted from a young male patient. The left had a normal root pattern but the right had four well-defined roots. The accessory root appeared to be the mesiopalatal which had a distinctly rounded cross-sectional profile. The other roots had the typical form characteristic of primary molar roots. Some degree of bifurcation can occur in the mesiobuccal roots of upper molars and the accessory root described in this report may represent an extreme example of such bifurcation.
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