Bleeding on probing and pocket probing depth in relation to probing pressure and mucosal health around oral implants.

OBJECTIVES: To assess the bleeding on probing (BOP) tendency and periodontal probe penetration when applying various probing forces at implant sites in patients with a high standard of oral hygiene with well-maintained peri-implant tissues. MATERIAL AND METHODS: Seventeen healthy patients with excellent oral hygiene in a maintenance program after having been treated for periodontitis or gingivitis were recruited. Missing teeth had been replaced using oral implants. The BOP and probing depth (PPD) were assessed at the mid-buccal, mid-oral, mesial and distal aspects of the buccal surfaces of each implant. Moreover, contralateral teeth were designated and assessed for BOP and PPD in the same locations and at the same observation visits. At each visit, implants and contralateral teeth were randomly assigned to one of the standardized probing forces (0.15 or 0.25 N). The second probing force was applied at the repetition of the examination 7 days later. RESULTS: Increasing the probing pressure by 0.1 N from 0.15 N resulted in an increase of BOP percentage by 13.7% and 6.6% for implants and contralateral teeth, respectively. There appeared to be a significant difference of the mean BOP percentage at implant and tooth sites when a probing pressure of 0.25 N was applied. A significantly deeper mean PPD at implant sites compared with tooth sites was found irrespective of the probing pressure applied. CONCLUSIONS: The results of the present study demonstrated that 0.15 N might represent the threshold pressure to be applied to avoid false positive BOP readings around oral implants. Hence, probing around implants demonstrated a higher sensitivity compared with probing around teeth.

The effect of surface ions on water adsorption to mica.

We have measured the adsorption isotherms of water on a single surface of freshly cleaved mica with K+ on the surface, and on mica where the K+ has been exchanged for H+. Using a very sensitive interferometric technique, we have found a significant difference between the two isotherms at submonolayer coverage, for relative vapor pressures p/p0 < 0.5. The K+-mica isotherm shows a pronounced convexity, suggesting distinct adsorption sites, whereas the H+-mica isotherm is flatter. The two isotherms converge above monolayer coverage. The results give a graphic demonstration of the importance of nanoscale surface heterogeneities for vapor adsorption at submonolayer coverage.

Precision thickness and refractive index imaging of molecular films.

We present an interferometric contrasting technique that allows visualizing the thickness and refractive index of a molecular film being part of an optical multilayer structure (etalon). Small wavelength shifts of the comblike etalon spectrum are transformed into measurable intensity variations using a second reference etalon (optical correlator), illuminated in series. A charge-coupled device camera acting as two-dimensional photometer is utilized to measure the optical spectral correlation (OSC) image. The performance of the here proposed optical spectral correlation method is demonstrated using very thin confined liquid films. We give a detailed signal-to-noise analysis. Subangstrom film thickness resolution is experimentally verified with single exposure images acquired at frame rates comparable to video standards (approximately 25 Hz). Finally, we describe the calibration procedures necessary to obtain an absolute quantification of the OSC image.