In-vitro effects of novel periodontal scalers with a planar ultrasonic piezoelectric transducer on periodontal biofilm removal, dentine surface roughness, and periodontal ligament fibroblasts adhesion.

OBJECTIVES: To compare ultrasonic scaler prototypes based on a planar piezoelectric transducer with different working frequencies featuring a titanium (Ti-20, Ti-28, and Ti-40) or stainless steel (SS-28) instrument, with a commercially available scaler (com-29) in terms of biofilm removal and reformation, dentine surface roughness and adhesion of periodontal fibroblasts. MATERIALS AND METHODS: A periodontal multi-species biofilm was formed on specimens with dentine slices. Thereafter specimens were instrumented with scalers in a periodontal pocket model or left untreated (control). The remaining biofilms were quantified and allowed to reform on instrumented dentine slices. In addition, fibroblasts were seeded for attachment evaluation after 72 h of incubation. Dentine surface roughness was analyzed before and after instrumentation. RESULTS: All tested instruments reduced the colony-forming unit (cfu) counts by about 3 to 4 log10 and the biofilm quantity (each p < 0.01 vs. control), but with no statistically significant difference between the instrumented groups. After 24-hour biofilm reformation, no differences in cfu counts were observed between any groups, but the biofilm quantity was about 50% in all instrumented groups compared to the control. The attachment of fibroblasts on instrumented dentine was significantly higher than on untreated dentine (p < 0.05), with the exception of Ti-20. The dentine surface roughness was not affected by any instrumentation. CONCLUSIONS: The planar piezoelectric scaler prototypes are able to efficiently remove biofilm without dentine surface alterations, regardless of the operating frequency or instrument material. CLINICAL RELEVANCE: Ultrasonic scalers based on a planar piezoelectric transducer might be an alternative to currently available ultrasonic scalers.

In-Vitro Measurement of Forces During Debridement with a Piezoelectric Ultrasonic Periodontal Scaler.

PURPOSE: This study investigated the magnitude, direction, and temporal aspects of the force applied during instrumentation with a piezoelectric ultrasonic periodontal scaler, compared this force with recommendations in the literature, and assessed the influence of the profession (dentist or dental hygienist) and calculus hardness. MATERIALS AND METHODS: The force applied by ten dental hygienists and six dentists during debridement of comparatively soft and hard artificial dental calculus with a piezoelectric ultrasonic scaler was recorded in-vitro. The total force and its components in three axes were statistically analysed. RESULTS: During debridement of soft artificial dental calculus, the mean total force applied by dental hygienists was 0.34 N (± 0.18 N, range: 0.13 N to 0.59 N) and by dentists 0.28 N (± 0.33 N, range: 0.06 N to 0.95 N), and the total force exceeded 0.5 N approximately 23% and 14% of the time for dental hygienists and dentists, respectively. During debridement of hard artificial dental calculus, the mean total force applied by dental hygienists was 0.63 N (± 0.40 N, range: 0.28 N to 1.64 N) and by dentists 0.57 N (± 0.17 N, range: 0.34 N to 0.76 N); the total force exceeded 0.5 N more than half of the time for both professions. On average, dental hygienists applied 1.85x (p = 0.04) and dentists 2.04x (p = 0.06) higher force on hard than on soft artificial calculus. However, dental hygienists and dentists used similar forces during the debridement of both hard (p = 1.00) and soft (p = 0.26) calculus. CONCLUSION: The force applied during the debridement of hard artificial dental calculus was statistically significantly higher than during the debridement of soft artificial dental calculus. No statistically significant difference between dentists and dental hygienists was found. The force applied by both groups on soft and hard artificial dental calculus frequently exceeded recommended values.

Safety and Feasibility of Noninvasive Electromagnetic Stimulation of the Phrenic Nerves.

BACKGROUND: Mechanical ventilation is widely used in ICU patients as a lifesaving intervention. Diaphragmatic atrophy and thinning occur from lack of contractions of the diaphragm during mechanical ventilation. It may prolong weaning and increase the risk of respiratory complications. Noninvasive electromagnetic stimulation of the phrenic nerves may ameliorate the atrophy seen with ventilation. The objective of this study was to show that noninvasive repetitive electromagnetic stimulation is safe, feasible, and effective to stimulate the phrenic nerves in both awake individuals and anesthetized patients. METHODS: A single-center study with 10 subjects overall, 5 awake volunteers and 5 anesthetized subjects. We used a prototype electromagnetic, noninvasive, simultaneous bilateral phrenic nerve stimulation device in both groups. In the awake volunteers, we assessed time-to-first capture of the phrenic nerves and safety measures, such as pain, discomfort, dental paresthesia, and skin irritation. In the anesthetized subjects, time-to-first capture as well as tidal volumes and airway pressures at 20%, 30%, and 40% stimulation intensity were assessed. RESULTS: Diaphragmatic capture was achieved in all the subjects within a median (range) of 1 min (1 min to 9 min 21 s) for the awake subjects and 30 s (20 s to 1 min 15 s) for the anesthetized subjects. There were no adverse or severe adverse events in either group, nor any dental paresthesia, skin irritation, or subjective pain in the stimulated area. Tidal volumes increased in all the subjects in response to simultaneous bilateral phrenic nerve stimulation and increased gradually with increasing stimulation intensity. Airway pressures corresponded to spontaneous breathing of ∼2 cm H2O. CONCLUSIONS: Noninvasive phrenic nerve stimulation can be safely performed in awake and anesthetized individuals. It was feasible and effective in stimulating the diaphragm by induction of physiologic and scalable tidal volumes with minimum positive airway pressures.

Efficient Thermobonding Process Forming a Polyurethane Based Diagnostic Catheter with Liquid Crystal Polymer.

Diagnostic and therapeutic catheters play an inevitable role in minimal invasive medical procedures. Unfortunately, standard catheters show a limited transducer density and high production efforts. We propose a novel catheter design and manufacturing method using a liquid crystal polymer (LCP)-based flexible printed circuit board (FPCB) and a thermoplastic polyurethane (TPU) elastomer tube. Both components are bond together with a low cost, additive free lamination process at a re-flow temperature of 250° C. The lamination process is improved with a laser welding seam and LCP-integrated microholes preventing delamination. Standardized Mechanical tests were conducted to characterize the bonding. A Peel strength of up to 8.5 N in the radial direction and a non plastic elongation in the axial direction of 10% provide evidence that the thermobonding process is suitable for the production of flexible and mechanically durable medical catheters featuring high electrode densities.

Electrodes for long-term esophageal electrocardiography.

The emerging application of long-term and high-quality ECG recording requires alternative electrodes to improve the signal quality and recording capability of surface skin electrodes. The esophageal ECG has the potential to overcome these limitations but necessitates novel recorder and lead designs. The electrode material is of particular interest, since the material has to ensure conflicting requirements like excellent biopotential recording properties and inertness. To this end, novel electrode materials like PEDOT and silver-PDMS as well as established electrode materials such as stainless steel, platinum, gold, iridium oxide, titanium nitride, and glassy carbon were investigated by long-term electrochemical impedance spectroscopy and model-based signal analysis using the derived in vitro interfacial properties in conjunction with a dedicated ECG amplifier. The results of this novel approach show that titanium nitride and iridium oxide featuring microstructured surfaces did not degrade when exposed to artificial acidic saliva. These materials provide low electrode potential drifts and insignificant signal distortion superior to surface skin electrodes making them compatible with accepted standards for ambulatory ECG. They are superior to the noble and polarizable metals such as platinum, silver, and gold that induced more signal distortions and are superior to esophageal stainless steel electrodes that corrode in artificial saliva. The study provides rigorous criteria for the selection of electrode materials for prolonged ECG recording by combining long-term in vitro electrode material properties with ECG signal quality assessment.