Efficacy of liposome-encapsulated ciprofloxacin in a murine model of Q fever.

Encapsulation of antibiotics may improve treatment of intracellular infections by prolonging antibiotic release and improving antibiotic uptake into cells. In this study, liposome-encapsulated ciprofloxacin for inhalation (CFI) was evaluated as a postexposure therapeutic for the treatment of Coxiella burnetii, the causative agent of Q fever. Intranasal treatment of male A/Jola (A/J) mice with CFI (50 mg/kg of body weight) once daily for 7 days protected mice against weight loss and clinical signs following an aerosol challenge with C. burnetii. In comparison, mice treated twice daily with oral ciprofloxacin or doxycycline (50 mg/kg) or phosphate-buffered saline (PBS) lost 15 to 20% body weight and exhibited ruffled fur, arched backs, and dehydration. Mice were culled at day 14 postchallenge. The weights and bacterial burdens of organs were determined. Mice treated with CFI exhibited reduced splenomegaly and reduced bacterial numbers in the lungs and spleen compared to mice treated with oral ciprofloxacin or doxycycline. When a single dose of CFI was administered, it provided better protection against body weight loss than 7 days of treatment with oral doxycycline, the current antibiotic of choice to treat Q fever. These data suggest that CFI has potential as a superior antibiotic to treat Q fever.

Preliminary images from an adaptive imaging system.

I-ImaS (Intelligent Imaging Sensors) is a European project aiming to produce real-time adaptive X-ray imaging systems using Monolithic Active Pixel Sensors (MAPS) to create images with maximum diagnostic information within given dose constraints. Initial systems concentrate on mammography and cephalography. In our system, the exposure in each image region is optimised and the beam intensity is a function of tissue thickness and attenuation, and also of local physical and statistical parameters in the image. Using a linear array of detectors, the system will perform on-line analysis of the image during the scan, followed by optimisation of the X-ray intensity to obtain the maximum diagnostic information from the region of interest while minimising exposure of diagnostically less important regions. This paper presents preliminary images obtained with a small area CMOS detector developed for this application. Wedge systems were used to modulate the beam intensity during breast and dental imaging using suitable X-ray spectra. The sensitive imaging area of the sensor is 512 x 32 pixels 32 x 32 microm(2) in size. The sensors' X-ray sensitivity was increased by coupling to a structured CsI(Tl) scintillator. In order to develop the I-ImaS prototype, the on-line data analysis and data acquisition control are based on custom-developed electronics using multiple FPGAs. Images of both breast tissues and jaw samples were acquired and different exposure optimisation algorithms applied. Results are very promising since the average dose has been reduced to around 60% of the dose delivered by conventional imaging systems without decrease in the visibility of details.

Vancomycin release behaviour from amorphous calcium polyphosphate matrices intended for osteomyelitis treatment.

Calcium polyphosphate (CPP) antibiotic delivery matrices were prepared using a unique processing technique involving the exposure of antibiotic-loaded CPP pastes to high humidity for 0, 5, or 24 h. After the designated gelling period, samples were dried for a minimum of 24 h. At several time points out to 130 h, the elution medium was monitored for vancomycin, Ca2+ ion and ortho and poly phosphate release levels. Vancomycin activity was also assessed after 1, 24 and 130 h, while solution 31P-NMR was used to monitor changes in chain length within a 24 hr gelled VCM disc throughout the elution process. The gelling and drying process significantly reduced the rate of vancomycin release during the initial 2-4 h of elution, while extending the effective antibiotic release period by an additional 80 h. The mild conditions associated with matrix fabrication readily allowed for vancomycin incorporation within an environment that did not disrupt antibiotic activity. Throughout the elution process, all sample groups experienced considerable swelling followed by some apparent bulk erosion. Phosphate chain lysis was clearly observed by the end of the elution period. Generally, no strong or consistent correlation existed between matrix degradation and antibiotic release for the treatment groups investigated. An ability to delay antibiotic release using CPPs in conjunction with this protocol supports further investigations into the potential of this matrix as a localized drug delivery system.

Oral cancer at a Tasmanian tertiary referral clinic, the Royal Hobart Hospital 1996-2002.

BACKGROUND: The Holman Clinic at the Royal Hobart Hospital includes a multi-disciplinary head and neck clinic which functions as a tertiary referral centre for Southern Tasmania and involves Ear Nose and Throat surgeons, Oral and Maxillofacial Surgeons, Plastic and Reconstructive Surgeons, Radiation Oncologists and Medical Oncologists. METHODS: The aim of this study was to examine retrospectively the number, gender distribution, age, site of lesion, histology, mortality and treatment modalities of the oral cancers referred to the Holman clinic at the Royal Hobart Hospital. The medical histories and a database of the Holman clinic were used as the sources of data for this study. A total of 101 patients were treated for oral cancer in the Holman clinic at the Royal Hobart Hospital from 1996 to 2002. There were 64 males and 37 females. RESULTS: The distribution of anatomical sites of the oral cancers in this study was as follows: 36 oral tongue lesions, 17 floor of mouth, 13 lip, five retromolar trigone, five mandibular alveolus, six buccal mucosa, nine palatal and 10 minor and major salivary gland cancers. The most common site of oral cancer was the tongue (35.6 per cent), followed by the floor of mouth (16.8 per cent) and lip (12.9 per cent). CONCLUSIONS: The majority of oral cancers were squamous cell carcinoma, except for the salivary gland cancers. The incidence of squamous cell carcinoma was between 67 and 100 per cent, depending upon the site involved. The trends found in this study are similar to those previously documented over the past 20 years.

Correlation of dental amalgam crevice corrosion with clinical ratings.

In vitro corrosion behavior of gamma 2-containing and gamma 2-free dental amalgams was examined under crevice conditions which simulated the amalgam-tooth interface. By means of potentiostatic testing, current-density/time behavior and integrated anodic current were measured for 16 hr. All of the amalgams demonstrated crevice corrosion susceptibility. Crevice corrosion propagation for gamma 2-free vs. gamma 2-containing amalgams was characterized by lower acceleration and maximum rates during the most dynamic period. Integrated anodic current results were correlated with marginal breakdown ratings reported in two clinical investigations. Strong and significant coefficients were found between integrated current and marginal breakdown ratings when gamma 2-containing and gamma 2-free amalgams were correlated as a single group, but not when correlated separately.

The response of dental amalgam to dynamic loading.

A conventional (gamma 2-containing) dental amalgam was fatigue-tested at 1800 and 80 cycles/min, employing uni-axial, sinusoidal loading, with R = -8. Compressive, tensile, and creep tests were conducted to characterize the alloy's static mechanical behavior. Tests were performed at 37 degrees C on specimens which were aged for seven days, at 37 degrees C. Fatigue-tested specimens were microscopically examined for fracture surface appearance and crack path. The amalgam demonstrated a frequency dependence and a significant reduction in fracture strength due to fatigue loading. The fatigue crack path was primarily intergranular in the gamma 1 phase and inclined at approximately 45 degrees to the principal stress axis. These observations are characteristic of some metals when subjected to low-frequency, elevated temperature testing where significant grain boundary sliding occurs, and therefore suggest a creep-fatigue interaction for this alloy.

Crevice corrosion products of dental amalgam.

The objective of this study was to determine the in vitro corrosion products that resulted from crevice corrosion of low- and high-copper dental amalgams. Specimens were potentiostatically polarized in a chloride-containing electrolyte while set against a PTFE surface to form a crevice. After 16 h, corrosion products were examined by light microscopy, SEM, EDS, and XRD. Analysis showed the presence of three previously reported products [Sn4(OH)6Cl2, SnO, and Cu2O] and a new product, CuCl, which formed on high-copper, gamma 2-free amalgams. Thermodynamic considerations show that CuCl is stable for the reported in vivo potentials of amalgam restorations and the high acidity and high chloride ion concentration associated with crevice corrosion.

Chemical and molecular weight analyses of prosthodontic soft polymers.

A number of studies have been made investigating the properties of dental prosthodontic soft polymer materials. In such materials, which are used as short-term denture soft liners, the polymer component is complexed with one or more plasticizers. This lowers the glass transition temperature, Tg, of the polymer by allowing greater chain mobility and produces a more flexible material. Little information is available relating to the polymer components of such soft-lining materials. The chemical composition and molecular-weight distribution of a polymer help to determine its ability to form a plasticized soft polymer-gel. In the present work, both pyrolysis depolymerization/gas chromatography (GC) and size exclusion chromatography (SEC) have been used to characterize 11 commercial polymer powders. By use of SEC and polymer standards having a narrow molecular-weight range, it has been possible for accurate molecular-weight distributions to be determined for all 11 powders. The peak molecular weights were found to be between 1.79 x 10(5) and 3.28 x 10(5). These values are above the molecular weight at which chain entanglement occurs. The polydispersity ratios (Mw/Mn) were between 2.09 and 4.48. Methacrylate polymers can be readily decomposed thermally to their constituent monomers, which, once recovered, can be analyzed by gas chromatography. The simple pyrolysis apparatus used in the present study was easily assembled and was capable of producing both qualitative and quantitative results. None of the commercial polymers analyzed gave methacrylate decomposition products with pendant chains greater than ethyl (-CH2-CH3). All of the commercial polymers successfully studied by the pyrolysis test method proved to be poly(ethyl [100-79%]/methyl [0-21%] methacrylate) polymers or co-polymers.

Corrosion and cytotoxicity evaluation of thermafil endodontic obturator carriers.

The purpose of this study was to evaluate the in vitro cytotoxicity of two metallic and two plastic Thermafil carrier materials, and to separately evaluate the in vitro corrosion behavior of the two metallic carriers. Stainless-steel, Ti-6AI-4V, Polysulfone, and Vectra carriers were evaluated for cytotoxicity using the ISO-recommended agar overlay test. The two metallic carriers were additionally corrosion tested in 0.9% NaCl solution for 174 wk, at 37 degrees C. Elemental analyses of the corrosion solutions were periodically conducted using inductively coupled plasma-mass spectroscopy. Agar overlay results showed that the four carrier materials were not cytotoxic to L929 fibroblasts. Inductively coupled plasma-mass spectroscopy results showed that the metallic materials had small mass loss rates. Scanning electron microscopy showed no evidence of pitting or crevice corrosion.

Trace-element analysis of human teeth and bone by proton-induced X-ray emission.

The objective of our study is to correlate Fe, Cu, Zn, Pb, Br, Sr, and Mo concentrations in human teeth crown, root, and bone.The samples, teeth from a lower jaw bone and the lower jaw bone itself, were obtained from a 97-yr-old female cadaver. Two hundred milligrams of crown and root of the teeth, and lower jaw bones were fixed to a Kapton film and irradiated with a 3.8-MeV external proton beam from an 8-MV FN Tandem Van de Graaff Accelerator.TheF-test was used to analyze the difference between crown, root, and bone. It resulted in the following: For Fe, Zn, and Pb, the comparison showed significant differences among the three sample populations of tooth crown, root, and bone; for Cu, Br, Sr, and Mo, the comparison showed no significant differences among all three sample populations.Several elements in the samples were highly interrelated.

Education in early detection of oral squamous cell carcinoma: a community outreach program.

An educational program consisting of a slide presentation and lecture, a demonstration of how to examine the oral soft tissues, and handout materials was presented to practitioners, hygienists, assistants, and other personnel in their office. A pretest, a critique by the participants, and a follow-up questionnaire were used to determine the value of the program.

The occurrence in mice of facial and mandibular abscesses associated with Staphylococcus aureus.

Swellings affecting the face and jaws of a strain of outbred BSVS mice are described. The swellings consisted of multiple abscesses which were most commonly associated with the mandible. Staphylococcus aureus of a single phage type was isolated from the abscesses. It is suggested that the organisms gained entry through the oral mucosa.

Effect of stepped light exposure on the volumetric polymerization shrinkage and bulk modulus of dental composites and an unfilled resin.

PURPOSE: To compare the volumetric polymerization shrinkage and dynamic bulk modulus of five resins and an experimental unfilled resin polymerized with a stepped power light and with a conventional one step curing light. MATERIALS AND METHODS: Parallel sided glass rings 5 mm in diameter and 2 mm high were etched for 5 min with hydrofluoric acid and silanated. The density and volume of the rings were calculated before they were filled with either SureFil, AEliteflo, Pertac II, Z100, or an experimental unfilled resin. When cured, the resin was bonded to the glass ring which produced a mold with a configuration C-factor of approximately 0.8. The resin was cured for 40 s on each side using either a one step curing light or a stepped power curing light. After curing, the specimens were weighed in air and in water to calculate their final density and volumetric shrinkage. Ten samples were made using each light system and for each resin (total of 100 samples). The bulk modulus was determined for each resin using an ultrasonic method, and the percentage filler contents were determined by thermogravimetric analysis. RESULTS: The mean +/- SD volumetric polymerization shrinkage values ranged from 3.10 +/- 1.19% for SureFil using the one step light to 12.35 +/- 1.38% for the unfilled resin using the stepped power curing light. Student-Newman-Keuls post hoc test separated the 10 different materials into three significant groups at P= 0.05. The unfilled resin exhibited the highest volumetric shrinkage followed by the flowable composite (AEliteflo). For all materials tested, there was no significant difference in the volumetric shrinkage values when the resin was cured with the one step or the stepped power curing light. There was no significant difference in the volumetric shrinkage values for the hybrid composites (Pertac II, Z100, and SureFil). The volumetric shrinkage values were highly sensitive to filler weight (P < 0.001). Except for Z100, there was no difference in the specific gravity values and velocities of the longitudinal and shear waves and bulk modulus when the one step and stepped power curing lights were used. The bulk modulus values ranged from 6.30 +/- 0.19 GPa for unfilled resin, to 17.10 +/- 1.09 GPa for Z100. Curing with the one step or the stepped curing light had no significant effect on the modulus values for any resin with the exception of Z100, P = 0.05. The bulk modulus values were highly sensitive to filler weight, and higher modulus values were associated with increased filler weight (P < 0.001). There was no significant difference between the bulk modulus of Pertac II and SureFil (P = 0.05).

Effect of stepped vs. continuous light curing exposure on bond strengths to dentin.

PURPOSE: To compare the 10-min and 24-hr shear bond strengths of three dentin bonding systems, polymerized with either a standard (Optilux 401) light for 60 s, or a stepped curing light (Elipar Highlight) that delivered a low light intensity for 10 s followed by high intensity for 50 s. MATERIALS AND METHODS: Three bonding systems were used to bond two resin-based composites (RBC) to dentin at 34 degrees +/- 2C using the two curing lights. Single Bond (SB) and Prime & Bond 2.1 (P&B) were used with Z100 RBC, and EBS bonding system was used with Pertac II RBC. Ten specimens from each combination were debonded at 37 degrees +/- 1C 10 min after starting to light cure the bonding system. Ten other specimens were stored in water at 37 degrees +/- 1C for 24 hrs before debonding at 37 degrees +/- 1C (total 120 teeth). RESULTS: The 10-min mean shear bond strengths were: Standard Cure; EBS 11.9 +/- 2.9 MPa, SB 14.6 +/- 2.2 MPa, P&B 14.7 +/- 4.2 MPa: Stepped Curing; EBS 7.4 +/- 2.1 MPa, SB 13.0 +/- 3.6 MPa, P&B 15.6 +/- 4.8 MPa. The 24-hr mean shear bond strengths were: Standard Cure; EBS 14.8 +/- 5.1 MPa, SB 25.1 +/- 3.3 MPa, P&B 25.2 +/- 8.8 MPa: Stepped Curing; EBS 15.1 +/- 4.6 MPa, SB 21.9 +/- 5.9 MPa, P&B 17.3 +/- 9.2 MPa. Three way ANOVA showed significant main effects for light, bonding system and time and no 2- or 3-way interaction effects at P = 0.01. The Least-Squares Means test with Sidak's adjustment for Multiple Comparisons showed that the bond strengths obtained using the standard light were significantly greater than the bond strengths obtained using the stepped curing light (P < 0.01). The 24-hr bond strengths were significantly greater (P < 0.01) than the 10-min bond strengths. The bond strengths obtained with EBS were significantly less than SB and P&B (P < 0.01), but there were no significant differences between SB and PB (P = 0.9752).

Mandibular fracture patterns in Tasmania, Australia.

BACKGROUND: No previous studies on mandibular fracture patterns in Tasmania, and very few elsewhere in Australia, have undertaken to discover which identified age, gender, aetiology, anatomical location of the fracture, period of injury, whether alcohol consumption was associated with the injury, and treatment of mandibular fractures. METHOD: A retrospective study was undertaken of 251 patients with fractured mandibles presenting to the Royal Hobart Hospital, Tasmania from 1993-1999. Data were obtained from the Oral and Maxillofacial Surgery unit fracture record books cross-checked with patients, impatient/outpatient hospital records. RESULTS: The male to female ratio was 4.5:1, with mandibular fractures most common in the male age group of 21-30 years. Assaults (55 per cent of all patients) were the major cause of fractures. Males accounted for 85.5 per cent of assaults, with punching being the most common method, followed by motor vehicle accidents (MVA), 18.3 per cent and sport, 16.7 per cent. In sport, Australian Rules Football was the most common cause, accounting for 45.2 per cent of sporting injuries. The site most frequently fractured was the angle of the mandible. Alcohol abuse was seen in 41.4 per cent of the patients with 84.6 per cent being male. Open reduction and internal fixation with miniplate osteosynthesis, was the preferred treatment modality. The results are compared with other series. CONCLUSIONS: Mandibular fractures are common in Tasmania, with the highest rates involved in assaults and sport (especially Australian Rules Football) and a low rate in MVA. These fractures commonly occurred in young males in which assaults, alcohol and social issues were associated. Therefore, preventive measures and strong public awareness addressing this group may be of benefit in reducing the rate of assaults and sporting injuries to the mandible.

In vitro comparison of 10-minute versus 24-hour shear bond strengths of six dentin bonding systems.

OBJECTIVE: Early bond strengths produced by dentin bonding systems should be sufficient to resist the polymerization shrinkage of resin composite. This study compared the 10-minute and 24-hour shear bond strengths of six dentin bonding systems: One-Step (OS), PermaQuik (PQ), Prime & Bond 2.1 (PB), Scotchbond Multi-Purpose (SBMP), Single Bond (SB), and Tenure Quik with Fluoride (TQ). METHOD AND MATERIALS: Each bonding system was used to bond composite to visibly moist dentin at 34 degrees C +/- 2 degrees C. The specimens were debonded at 37 degrees C +/- 1 degree C 10 minutes after the start of light curing of the bonding system, and the results were compared with the 24-hour bond strengths. The mode of failure was recorded. RESULTS: The 10-minute mean shear bond strengths were: OS, 16.4; PQ, 14.3; SB, 14.0; PB, 12.7; TQ, 10.7; and SBMP, 9.3 MPa. The 24-hour mean shear bond strengths were OS, 23.3; PB, 20.8; SB, 20.3; PQ, 19.4; TQ, 11.2; and SBMP, 10.0 MPa. The 10-minute mean shear bond strengths of OS, PQ, PB, and SB bonding systems were significantly less than the 24-hour values. More dentinal fractures and mixed failures were observed with OS, PQ, and PB. Systems with higher bond strengths had more resin penetration into the lateral dentinal branches. CONCLUSION: The 10-minute mean shear bond strengths were all less than 17 MPa, and the 10-minute bond strengths were less than the 24-hour values.

New trends in antibiotic prophylaxis of infective endocarditis in patients undergoing surgery in the oral cavity.

Viridans-streptococci, which normally reside in the oral cavity, are still the most common pathogens in infective endocarditis. During surgical procedures in the oral cavity, pharynx and respiratory tract, microorganisms may disseminate into the blood and cause infective endocarditis in predisposed patients. It is, therefore generally considered that these patients should be protected during surgery by an effective and simple antibiotic regimen. During recent years new recommendations for prevention of endocarditis have been presented in several countries. Single high dose amoxycillin or 2-dose phenoxymethylpenicillin are used in normal risk patients while 2-dose erythromycin or single high dose clindamycin may be used in patients allergic to penicillins. Parental agents are usually recommended in high risk patients with prosthetic heart valves, however, some countries prefer to administer peroral prophylaxis. Topical prophylaxis in the oral cavity is not included in any national recommendation, but may decrease the magnitude, as well as the frequency, of postsurgical bacteremia. Commonly used antiseptics such as chlorhexidine are not selective enough and causes overgrowth of some viridans-streptococci. More selectively acting agents, such as topical vancomycin, appear to be more suitable.

Managing constipation using a research-based protocol.

Constipation, a common health problem particularly for elderly and hospitalized patients, can cause abdominal pain, discomfort, gas, headaches, nausea, anorexia, a bad taste in the mouth, and potentially adds to functional loss and length of stay. As part of a quality improvement initiative, a research-based interdisciplinary protocol was developed to prevent constipation in hospitalized immobile vascular surgery patients. Using a combination of dietary fiber, increased fluid, and hygiene measures over a 3-year period, incidence of constipation was reduced from 59% to about 9%. The incidence of impaction was eliminated and requests for laxatives and enemas were reduced from 59% to about 8%.

The accuracy of medical history information in referral letters.

BACKGROUND: Accurate medical history information is essential for good patient care and should be notified in the letter of referral. The aim of this study was to investigate the subjective opinion that the medical information in a large number of referrals is either inaccurate or non-existent. METHODS: Medical histories from 54 patients with positive medical history findings upon taking the medical history at the initial consultation appointment were compared to the medical information supplied in the referral letter. RESULTS: Overall, medical information was only 58.8% complete with dental referrals being 55.2% complete and medical referrals 62.4%. The majority of referral letters (70.4%) missed at least one relevant finding and only 29.6% of referrals were 100% complete. CONCLUSIONS: The results of this study suggest that the standard of referral letters needs to be improved as the received referrals were generally incomplete and contained inaccurate information. This highlights the need for each and every practitioner to take their own detailed medical history and not rely on the information supplied in the referral.