Biomedical subjects

Martine Wevers

Publications and source records attributed to Martine Wevers.

5 recordsLinked to original sources

PubMed2006

Structural and radiological parameters for the characterization of jawbone.

OBJECTIVES: The aim of this study was to determine the Hounsfield values of selected bone sites on a computed tomography (CT) scan of the jaw and to investigate the relationship between this radiological parameter and structural parameters. MATERIALS AND METHODS: A selection of 24 bone samples out of eight cadaver human jaws was made. The following parameters were measured: Hounsfield value in the jaw (HU1) determined by a first CT scan, Hounsfield value of the excised bone specimen (HU2) by a second CT scan, bone mineral density (BMD) by a dual-energy X-ray absorptiometry scan, bone volume (BV/TV) by the microfocus CT scan, first peak transmission time (T(US-1)) and first zero crossing transmission time (T(US-2)) by an ultrasound measurement and Young's modulus (E(MECH)) by a compression test. RESULTS: Thirteen specimens were composed of a mix of trabecular and a small amount of cortical bone, while another 11 specimens were composed of trabecular bone only. A good correlation was found between the HU value of the specimen (HU2) and BMD (rho = 0.99), BV/TV (rho = 0.97), T(US-1) (rho = -0.83), T(US-2) (rho = -0.87) and E(MECH) (rho = 0.83). For the pure trabecular bone specimens, the HU value of the excised bone specimen (HU2) was highly correlated (rho = 0.95) with the HU value of the total jaw scan (HU1). For mixed trabecular-cortical bone specimens, this relationship was weak (rho = 0.57). CONCLUSION: With the current CT scan technology, predictions of the mechanical properties of trabecular jaw bone based on Hounsfield values were only valid for jaws with a thin layer of cortical bone. For jaws with a thicker cortical layer, the prediction of the mechanical properties decreased significantly.

Absorptiometry, Photon↗

PubMed2006

Effect of controlled early implant loading on bone healing and bone mass in guinea pigs, as assessed by micro-CT and histology.

Without controlled loading, the failure of early loaded oral implants is higher than in delayed loading, unless loading regimens can be identified that stimulate bone formation. The purpose of this study was to investigate whether controlled early loading optimizes osseointegration. Six series of guinea pigs received percutaneous implants in both tibiae. One implant was stimulated, the contra-lateral served as the control. The strain rate amplitude varied from 1,620 to 12,000 microstrain s(-1). In vivo microfocus computed tomography (micro-CT) was used to study the peri-implant bone at three time points: 1 wk after implantation, but before starting stimulation (V1); 2 wk after stimulation (V2); and 4 wk after stimulation, after the guinea pigs were killed (PM). Bone implant contact and bone mass [BM (%) bone occupied area fraction] were analyzed. The implant failure was 5.9% (six control/one test). Although bone implant contact did not significantly differ, bone mass in the distal half peri-implant marrow cavity was significantly higher around test implants. Strain rate amplitude and the difference in bone mass between test and control implants were inversely correlated. A strain rate amplitude of 1,620 microstrain s(-1) in the cortical bone at a distance of 1.3 mm from the implant showed the highest effect. Based on these results, early loading did not negatively affect the implant outcome. On the contrary, an improved bone reaction in the marrow cavity around early loaded implants was achieved.

Animals↗

PubMed2005

Validation of microfocus computed tomography in the evaluation of bone implant specimens.

BACKGROUND: Microfocus computed tomography (muCT) is an emerging technique owing to its speed, full three-dimensional information, and nondestructive properties. PURPOSE: The aim of this study was to explore the efficacy of a muCT system (Philips HOMX 161, Philips Medical Systems GmbH, Hamburg, Germany) for visualization of the bone structure around screw-type titanium implants by comparing muCT images with their histologic homologues. MATERIALS AND METHODS: Eight screw-type titanium implants were placed in the femoral condyles of two goats. After the excised implant-bone specimens were embedded in resin, three-dimensional muCT of the excised implant and bone specimens was performed. Histologic sections were subsequently made. A total of 150 histologic sections were matched with muCT images. RESULTS: Bone trabeculae were clearly visible on the muCT scans. However, bone close to the implant or present in the apical surface features of the implant could not be detected. The overall matching between muCT scans (slices) and the histologic sections was 89%. CONCLUSION: Investigation of trabecular bone around titanium implants by muCT can be considered highly reliable for determining trabecular bone parameters, with the exception of measuring direct bone-to-implant contact.

Animals↗

PubMed2004

The physical and antimicrobial effects of microwave heating and alcohol immersion on catheters that are reused for clean intermittent catheterisation.

INTRODUCTION: Due to worldwide different health insurance policies, patients are often forced to reuse the catheters when performing Clean Intermittent Catheterisation (CIC). We have compared the physical qualities and the antimicrobial effects of two methods of reusing catheters: microwave heating and storage of the catheters in a 70% alcohol solution. The studies were performed during different lengths of time. MATERIALS AND METHODS: Three types of catheters (a standard polyvinylchloride catheter, a special polyvinylchloride catheter with flexible Ergothan tip and a prelubrified catheter), normally intended for single use, were submitted to the effect of a microwave oven (Multitech 215 High Grade and Whirlpool M220 750 W and 1000 W with rotating plate) or preservation in a 70% alcohol solution. To study the effects of microwave heating, a recipient of water was placed in the oven to spread the microwaves and to absorb the heat. The catheters were placed in a resealable plastic bag (Ziploc. To study the effects of preservation in a 70% alcohol solution, the catheters were immerged in the solution for different lengths of time. Thereafter were the physical qualities of the catheters evaluated by using the technique of Differential Scanning Calorimetry (DSC). The antimicrobial effect of the method was evaluated after grafting the catheters with pathogenic E. coli, P. aeruginosa or S. aureus strains. RESULTS: Microwave heating up to 12 minutes at 750 W caused only minimal changes in the physical qualities of all the catheters. However, there was only an antimicrobial effect of the microwave heating on E. coli and not on P. aeruginosa or S. aureus. If the catheter remained longer than 45 minutes in a 70% alcohol solution, the physical qualities of the catheter changed either minimal in the special polyvinylchloride catheter with flexible Ergothan top but changed significantly in the prelubrified catheter). However, already after 5 minutes of immersion in the 70% alcohol solution there was a complete antimicrobial effect on E. coli, P. aeruginosa and S. aureus in all catheters. CONCLUSIONS: It should be recommended to patients on CIC to use a sterile packed and not previously used catheter. In this study we have shown that immersing the catheters in a 70% alcohol solution during 5 minutes can effectively disinfect the catheter without jeopardising the physical qualities. Thereafter, the catheters could be placed in a resealable (e.g. Ziploc bag without being rinsed under water, in order that the few drops of alcohol cause alcohol vapours within the closed plastic bag and maintain the antimicrobial effect.

Equipment Contamination↗

PubMed2004

Age calculation using X-ray microfocus computed tomographical scanning of teeth: a pilot study.

To correlate dental age with an individual's chronological age based on the calculated volume ratio of pulp versus tooth volume measured, an X-ray microfocus computed tomography unit (microCT) with 25 microm spatial resolution was used to non-destructively scan 43 extracted single root teeth of 25 individuals with well-known chronological age. Custom-made analysis software was used by two examiners to obtain numerical values for pulpal and tooth volume. The ratio of both was calculated and statistically processed. No significant intra- or inter-examiner differences were found. In fact, a very strong concordance correlation coefficient was found. Linear regression analysis showed a coefficient of determination (r) of 0.31 which suggests that there is a rather weak correlation between the volume ratio of pulp versus tooth and biological age. Although rather time consuming, this technique shows promising results for dental age estimation in a non-destructive manner using X-ray microfocus computed tomography.

Adult↗