Peri-implantitis cleaning instrumentation influences the integrity of photoactive nanocoatings.

OBJECTIVE: To determine in vitro the loss of integrity caused on photocatalytic anatase coated implant surfaces by clinical instrumentation through changes in surface topography and loss of functionality. METHODS: Anatase-coated titanium discs were treated with diamond burs, polishers, plastic and metal hand instruments, air scaler and air flow devices. The pressure exerted through instrumentation was measured online. Surface topography was evaluated through scanning electron microscopy and contact profilometry, surface function through hydrophilization capacity upon UV-A activation. RESULTS: Treatment with diamond burs and instruments with metal tips resulted in an increase of roughness. Use of silicone polishers led to smoothening, which was more pronounced on the anatase surface. Plastic instruments, the air abrasive system and rubber cups left the surfaces intact. Functionality was partially lost on surfaces subjected to hand instruments and completely lost upon diamond burs and silicone polishers. SIGNIFICANCE: The integrity of functional nanocoatings depends on the applied instrumentation. Air flow device, rubber cup with polishing paste and plastic tipped instruments prevent damage on these nanosurfaces and may be preferably used when decontaminating anatase and other nanocoatings in a clinical setting.

[Effect of fenestration of the cochlea on the vibration of the round window membrane]. / Effekt der Promontorialfensterung auf die Schwingung der Rundfenstermembran - experimentelle Studie.

Drilling a promontory window and coupling an FMT into the scala tympani may be a surgical alternative to stapes surgery in obliterative tympanosclerosis. Aim of this experimental study on human temporal bones was to measure changes of the acoustic transfer function from the tympanic membrane to the round window membrane after drilling a promontory window and insertion of a floating mass transducer.Laser vibrometry and acoustic measurements were performed on 11 temporal bone preparations equipped with a microphone attached to the round window. Calibrations were carried out to allow determination of SPLs affecting the cochlea after drilling a promontory window leaving the membranous inner ear intact and after insertion of an FMT into the cavity (with or without slight pressure).Drilling a promontory window does influence the transfer function. Insertion of the FMT with additional slight pressure further changes the transfer function.The presence of a promontory window changes the acoustic transfer function to the round window. Further investigations are needed to correlate the qualitative results with the audiological results after "third window vibroplasty" (inserted floating mass transducer without stimulation).

Detection of tympanic membrane movement using film patch with integrated strain gauge, assessed by optical coherence tomography: experimental study.

OBJECTIVE: We report an ex vivo and in vivo experimental study of a device designed to measure tympanic membrane movement under normal and pathological conditions, assessed using optical coherence tomography. MATERIALS AND METHODS: We designed two types of flexible, round film patch with integrated strain gauge, to be attached to the tympanic membrane in order to measure tympanic membrane movement. Tympanic membrane attachment was assessed using optical coherence tomography. The devices were tested experimentally using an ex vivo model with varying middle-ear pressure. RESULTS: Optical coherence tomography reliably assessed attachment of the film patch to the tympanic membrane, before and after middle-ear pressure changes. Strain gauge voltage changes were directly proportional to middle-ear pressure recordings, for low pressure changes. Tympanic membrane perforations smaller than 2 mm could be sealed off with the film patch. CONCLUSION: Attachment of the film patch with integrated strain gauge to the tympanic membrane was not ideal. Nevertheless, the strain gauge was able to precisely detect small pressure changes within the middle ear, in this experimental model.

[Tensometry - development of a measurement technique of the tube function in a temporal bone model]. / Tensometrie - Entwicklung eines Langzeitmessverfahrens der Tubenfunktion am Felsenbeinpräparat.

OBJECTIVE: Middle ear pressure depends widely on the function of the eustachian tube. Tube dysfunction is often a trigger for middle ear diseases like chronic otitis media but also for barotrauma. Patients with impaired tubal function should not be exposed to situations with extreme pressure changes. Until today, there is no valid examining method for long-time measuring of the development of middle ear pressure. MATERIAL AND METHODS: The basic idea was to develop a thin flexible film with integrated strain gauges made of platinum and gold, which can be applied directly on the surface of the tympanic membrane. Using these, shifts or distensions of the tympanic membrane in a temporal bone model can be measured and documented. RESULTS: We were able to show that the measuring system was sensitive enough to register pressure variations in the middle ear volume of a temporal bone model. While using a full bridge design of the strain gauge resistors it could be shown that the measuring voltage of the strain gauges were in phase of the pressure measurement curve or according to the positioning in opposite phase. In single resistor mode the measurement were not so positioning depended. Measuring tympanic membrane movement in case of perforation was feasible. CONCLUSIONS: To improve the longtime stability of the strain gauge film the next development step will be to make a new design with Konstantan resistors (CU-Ni-Mn). After a testing period, longtime measurements in clinical studies will follow.

[Thermographic investigations during stapedotomy using a CO2 laser]. / Thermografische Untersuchung während der CO2-Laserstapedotomie.

BACKGROUND: Temporary sensorineural hearing losses after CO(2) assisted stapes surgery have been described in literature. Whether thermal effects are the reason for this side effect is still unclear. The specific aim of this research is to demonstrate the thermal spread during CO(2) laser stapedotomy using a high-speed infrared camera. MATERIAL AND METHODS: Thermal depth effects in physiological saline solutions were examined in cochlea models (glass capillary tube, crystal cuvette and temporal bone preparation). Temperature changes and exchange processes after CO(2) laser application were measured using a high-speed infrared camera. Visualization of gas bubbles triggered by vaporisation underneath the stapes footplate after CO(2) shot was achieved with a high-speed camera. The footplate perforations were performed with a scanner system using a micromanipulator (laser power 20 W, 0.6 mm diameter, continuous wave, duration of 40 ms). RESULTS: Homogenous temperature increases of more than 100°C were measured on the surface of the footplate and 0.25 mm within the capillary tube after single shot CO(2) laser stapedotomy. Gas bubbles may cause isolated temperature increases of up to 65 K. These effects were found in depths of up to 2 mm underneath the stapes footplate. CO(2) shots on the saline solutions with parameter used for initial laser application may lead to temperature increases between 20-65 K in depths of 3-6 mm. CONCLUSIONS: CO(2) applications to an opened inner ear with the same laser parameter used for initial shot on the stapes footplate should be avoided.