Richard J. Blankenau

Argon laser effect on demineralization of human enamel

Previous studies have recorded the reduction of caries-like lesions in extracted human teeth that have been irradiated with CO2 laser. Other studies have shown a decrease in dissolution rate of enamel that has been irradiated with CO2 laser and acid resistance. This study was conducted to evaluate the effects of Argon laser irradiation on acid resistance and demineralization of dental enamel. Human enamel was laser irradiated with approximately 60 J/cm2 and 120 J/cm2. The amount of demineralization was determined in a rotating disk assembly (0.1 M acetate buffer, pH-4.5) for 24 hours and the results determined and plotted against the nonlased control using microradiographs and computerized imaging. The amount of dissolution of tooth structure lost to demineralization in 4.5 pH acid bath in a 24 hour period was reduced from approximately 140 micrometers to approximately 70 micrometers . This study show that demineralization is reduced when human enamel is exposed to Argon laser irradiation.

Effects of argon laser curing on dentin shear bond strengths

Previous studies have demonstrated the ability of the argon laser to polymerize light activated materials and improve enamel shear bond strengths. This study was conducted to evaluate the effects of the argon laser on dentin shear bond strengths of current dentin bonding systems. Argon laser (HGM Model 8) at 231 mw and 280 mw, 5 second bonding agent, 10 seconds composite and a conventional curing light (Translux EC/Kulzer) at 10 seconds bonding agent, 20 second composite were used to polymerize samples of dentin bonding systems: Scotchbond Multi-Purpose Plus (3M) and Prime Bond (Dentsply/Caulk), both with TPH (Dentsply/Caulk) composite. A flat dentin bonding site (600 grit) was prepared on the buccal surface of extracted human teeth. Twelve samples were made for each set of parameters for both laser and conventional light totaling 60 samples. Samples were stored in distilled water in light- proof containers for 24 hours at 37 degree(s)C. Shear bond strengths (MPa) were determined for each sample on the Instron testing machine. Mean values were calculated for each set of data and ANOVA with Fisher PLSD were used for statistical analysis. The argon laser provided bond strengths that were 21 - 24% greater than those of the conventional curing light system.

Response of associated oral soft tissues when exposed to argon laser during polymerization of dental resins

Polymerization of dental resins with Argon laser produces restorations with improved physical properties when compared to conventional visible‐light polymerization techniques. However, the possibility of damaging adjacent soft tissues has not been addressed.

Enamel cavosurface bevels finished with ultraspeed instruments

Rating scores ranked the straight fissure bur first for producing the smoothest and most distinct bevel. The 40-fluted and 12-fluted finishing burs ranked second and third, respectively, and the superfine diamond stone was judged to produce the roughest and least distinct bevel. In selecting an instrument for finishing an external enamel cavosurface bevel, the results of this study suggest that a straight fissure bur will produce the most distinct and smoothest bevel when ultrarotational speeds are used. Results also indicated the superfine diamond stone to be the least desirable instrument for preparing a bevel in enamel.

Argon laser application to endodontics

The application of laser technology to endodontics has been studied for some time. At the present time several major problems are being investigated: (1) removal of infected tissues, (2) sterilization of canals, (3) obturation of canals, and (4) preservation of the vitality of supporting tissues. This list is not intended to imply other problems do not exist or have been solved, but it is a starting point. This paper reviews some of the literature that relates to laser applications to endodontics and concludes with some of the findings from our investigation.

In-vivo carieslike lesion prevention with argon laser: pilot study

In vitro research has demonstrated the ability of argon laser irradiation to reduce demineralization or loss of tooth structure. This clinical pilot study was conducted to investigate the effectiveness of this procedure in vivo. Using the Ogaard model of producing demineralization, the experimental teeth were irradiated with argon laser (primarily 488 nm and 514 nm) of 250 mW, approximately 12 J/cm2 fluence, prior to banding. Polarized light evaluation of the sectioned, extracted teeth showed reduced demineralization in the experimental teeth as compared to the bilateral control teeth. Lower powered argon laser irradiation significantly reduced demineralization clinically.

Comparison of three types of light-curing devices

Shortened curing times for light activated composites have been sought for many years. This study was conducted to compare diametral tensile strengths (DTS) of four composites cured with three light curing devices: halogen lamp, argon laser and plasma arc. Twelve samples were made for each composite and light curing device for a total of 192 samples. Diametral tensile strengths were measured on the Instron testing machine and statistical analysis performed using ANOVA and Fisher PLSD. Results indicate there wee no statistical differences in the DTS of the composites tested as a result of the curing light source. The Plasma Arc curing light was able to produce statistically equal diametral tensile strengths in 3 and 6 seconds as compared to the argon laser in 10 seconds and the halogen light in 40 seconds. Supported in part by Dental Medical Diagnostics.

Effect of beam size on composite polymerization

Previous studies have demonstrated the ability of the Argon laser and conventional curing light to polymerize light- activated materials. This study was conducted to evaluate the effect of beam size on the diametral tensile strengths of a composite resin. The Argon laser (HGM Model 8) at 280 mw and 450 mw and beam size of approximately 5 mm , 8 mm, and 13 mm, with 10 second exposure were used to polymerize samples of TPH (L.D. Caulk) composite resin. The conventional curing light (the Max/L.D. Caulk) with beam sizes of 8 mm and 13 mm and 20 seconds exposure were used to polymerize Silux Plus (3M) composite resin. Twelve samples were made for each set of parameters for a total of 96 samples. The samples were stored in light-proof containers for 24 hours at room temperature and then tested on the Instron testing machine for diametral tensile strengths (MPa). Mean values were calculated for each set of data and ANOVA and Fisher PLSD were used for statistical analysis. Results indicate that in this study there was no statistical difference in diametral tensile strengths (MPa) between the beam sizes for a given power setting and light source.

Surface hardness comparison of resins polymerized by argon, xenon, and conventional light sources

A great deal of discussion has taken place regarding how to properly polymerize light activated resins. Claims are made that effective testing can be made by using surface hardness tests on samples with various dental instruments. Although these tests would probably identify a material that had been very poorly polymerized it would not identify materials that were properly polymerized. The lack of consistent, reproducible forces and evaluation of the results make these test practically worthless. Surface hardness which is important clinically has value when combined with evaluation of the surface immediately adjacent to the light source and the surface adjacent to the tooth. Also immediate and 24 hour testing to allow for continued polymerization is helpful in determining how to achieve best results for our patients. A variety of new light sources have been introduced to dentistry with claims of faster and better polymerizations. The visible light units are also undergoing improvements to include built in meters to monitor light output. The purpose of this study was to evaluate the top and bottom surface hardness of a composite resin using the following light sources: argon, xenon, and two visible light sources.

Management of cyclosporine-induced gingival hyperplasia by use of an argon laser

This is a report of a case study with interesting laser applications. A 7 year old female was referred to us for treatment of hyperplastic tissue. At age two the patient had successfully undergone a liver transplant. She had undergone two periodontal surgeries under general anesthetic for the same soft tissue problem. Other possible complications were chronic sinusitis and frequent headaches. She has allergies to penicillin and sulfa. Her daily medications are Predisone and Cyclosporin. We consulted with her transplant team and they had no contraindication for the proposed dental surgery. The doctor placed her on prophylactic erythromycin for the procedure, as a preventive measure. The patient desired not to have any more general anesthetics administered. Clinical examination revealed electric pulp tests were normal for all teeth tested. No visible carious lesions were observed and there was no need for radiographs at this time. Soft tissue revealed red inflamed fibrous tissue consistent with gingival hyperplasia. Probing demonstrated 4 - 6 mm pockets around the anterior teeth.