Biomedical subjects

J Mouhyi

Publications and source records attributed to J Mouhyi.

5 recordsLinked to original sources

PubMed2000

Adsorption of peroxidase on titanium surfaces: A pilot study.

The present study demonstrates the in vitro and in vivo adsorption of peroxidase onto titanium surfaces. Titanium foils (mean +/- SEM: 365 +/- 2 mm(2), n = 114) were incubated during 30 min with lactoperoxidase (4 mg in 5 mL 100 mM phosphate buffer pH 7). After 15 washings by H(2)O, titanium foils were incubated with o-phenylenediamine (6 mg/mL) and H(2)O(2) (7 mM) during 30 min. The reaction was then stopped by the addition of HCI 1M and the absorbance of the liquid phase was read on a spectrophotometer at 492 nm. In vitro adsorbed lactoperoxidase onto titanium surfaces was 0.70 +/- 0.05 ng/mm(2) (mean +/- SEM, n = 30). X-ray photoelectron spectroscopy confirmed the incorporation of protein nitrogen onto titanium surfaces: the nitrogen atomic percentage increased from 0.9 +/- 0.3 to 12.7 +/- 0.2% (n = 3) and from 3.7 +/- 0.1 to 14.4 +/- 0. 4% (n = 5) when titanium foils were incubated in the lactoperoxidase solution during 30 min and 24 h respectively. In vivo, oral peroxidases adsorbed on titanium healing abutments from 0.01 to 0.58 ng/mm(2) (n = 19) after 2 weeks in the oral environment.

Adsorption↗

PubMed2000

Re-establishment of the atomic composition and the oxide structure of contaminated titanium surfaces by means of carbon dioxide laser and hydrogen peroxide: an in vitro study.

BACKGROUND: In clinical situations with peri-implant bone resorption, re-integration of the exposed implant surface is sometimes preferable, which requires a clean surface. Previous investigations have shown that cleaning of contaminated titanium surfaces using chemical and abrasive methods is difficult. PURPOSE: The aim of this investigation was to evaluate the efficacy of different combinations of chemical and physical methods (citric acid, hydrogen peroxide, and carbon dioxide [CO2] laser irradiation) for removal of contaminants and subsequent reconstruction of the surface oxide of intraorally contaminated titanium foils. MATERIALS AND METHODS: Commercially pure titanium foils (99.6%, 5 x 5 mm in size) were contaminated by placement on dentures in volunteering patients, simulating a peri-implantitis situation. The contaminated foils and clean control foils were treated by seven and six combinations of citric acid, hydrogen peroxide, and CO2 laser irradiation, respectively. The effect of the cleaning procedures was evaluated by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). RESULTS: The initial elemental composition of the contaminated foils was 70% carbon (C), 20% oxygen (O), 10% nitrogen (N), and only traces of titanium (Ti) (< 1%). One treatment proved to be more effective than the others: irradiations by 5-second cycles of superpulsed CO2 laser at a power of 7 W, 10-millisecond pulse width, and with an 80-Hz frequency on a wet surface, followed by repeated application of supersaturated citric acid for 30 seconds, each time followed by rinsing with ultrapure water until all tissue remnants had been removed. Finally, hydrogen peroxide of 10-mM concentration was added to the implant surface and evaporated by CO2 laser at the same settings. This treatment protocol resulted in 10% Ti, 45% O, 41% C, and 2 to 3% N, a composition comparable to that of unused foils: 9% Ti, 40% O, 48% C, and traces of N and chlorine (CI). X-ray photoelectron spectroscopy profiles showed that the thickness of the surface oxide was restored and even augmented with this protocol for treatment of contaminated titanium. CONCLUSION: A combination of citric acid, hydrogen peroxide, and CO2 laser irradiation seems to be effective for cleaning and reestablishment of the atomic composition and oxide structure of contaminated titanium surfaces.

Carbon↗

PubMed2000

The soft tissue response to contaminated and cleaned titanium surfaces using CO2 laser, citric acid and hydrogen peroxide. An experimental study in the rat abdominal wall.

The soft tissue response to clinically retrieved and decontaminated cover screws was evaluated in a rat model. The cover screws were cleaned by using citric acid, sterile water, hydrogen peroxide and CO2 laser alone or with a combination of these. In addition, decontaminated but not cleaned and unused cover screws were used as negative and positive controls, respectively. After cleaning the cover screws were implanted in the abdominal wall of the rat for 6 weeks. The thickness of the fibrous capsule and the number of macrophages within the capsule were measured by means of light microscopical morphometry. As compared to the negative control, CO2 laser on dry surface, CO2 laser + hydrogen peroxide and the positive control had statistically significant thinner fibrous capsules. As compared to the positive, only laser alone resulted in a similar tissue response. It is concluded that CO2 laser used alone or in combination with hydrogen peroxide may be used clinically for sufficient decontamination of titanium surfaces.

Abdomen↗

PubMed1999

Temperature increases during surface decontamination of titanium implants using CO2 laser.

The purpose of the present in vitro investigation was to measure temperature changes at the implant surface when using pulsed CO2 laser in a simulated implant surface decontamination protocol. Six threaded titanium implants were placed in a fresh resected pig mandible. A 4 x 4 mm defect was created buccally to each implant in order to expose the implant head and approximately 5 threads. Temperature changes were monitored by two thermocouples placed near the dehiscence and at the apical part of the implant. Several setting combinations of the CO2 laser with regard to output power, pulse width, pulse repetition rate and irradiation time were tested on dry and wet (distilled water) surfaces. Only minor temperature increases were measured when lasing wet titanium surfaces, while the temperature at dry surfaces exceeded the proposed thresholds for bone damage at clinically relevant settings. It is concluded that the CO2 laser when used on a wet implant surface in a pulsed mode at 8 W/10 ms/20 hz during 5 s induces a temperature increase of less than 3 degrees C. This would minimize the risk of temperature induced tissue damage as a result of lasing implant surfaces.

Animals↗

PubMed1998

An XPS and SEM evaluation of six chemical and physical techniques for cleaning of contaminated titanium implants.

The purpose of the present study was to analyse clinically failed and retrieved implants prior to and after cleaning by means of scanning electron microscopy (SEM) and X-ray induced photoelectron spectroscopy (XPS) as compared to unused controls. Six different chemical and physical techniques for cleaning of contaminated titanium implants were evaluated: 1) rinsing in absolute ethanol for 10 min, 2) cleaning in ultrasonic baths containing trichloroethylene (TRI) and absolute ethanol, 10 min in each solution, 3) abrasive cleaning for 30 s, 4) cleaning in supersaturated citric acid for 30 s, 5) cleaning with continuous CO2-laser in dry conditions at 5 W for 10 s, 6) cleaning with continuous CO2-laser in wet conditions (saline) at 5 W for 10 s. SEM of failed implants showed the presence of contaminants of varying sizes and XPS showed almost no titanium but high carbon signals. XPS of unused titanium implants showed lower levels of titanium as previously reported, probably due to contamination of carbon which increased with time in room air. Cleaning of used implants in citric acid followed by rinsing with deionized water for 5 min followed by cleaning in ultrasonic baths with TRI and absolute ethanol gave the best results with regard to macroscopical appearance and surface composition. However, as compared to the unused implants the results from an element composition point of view were still unsatisfactory. It is concluded that further development and testing of techniques for cleaning of organically contaminated titanium is needed.

Air Abrasion, Dental↗