Diode laser radiation and its bactericidal effect in root canal wall dentin.

OBJECTIVES: The aim of this study was to investigate the antibacterial effect of a diode laser in deep root canal dentin. BACKGROUND DATA: The microbial colonization of root canal dentin can lead to failures in conventional endodontic treatment if an inadequate bacterial reduction only is achieved through canal treatment and chemical disinfection. METHODS: 100 microm, 300 microm and 500 microm bovine dentin slices obtained by longitudinal sections were sterilized and inoculated on one side with an Enterococcus faecalis suspension. Laser radiation was performed on the opposite side with the diode laser (810 nm) at a setting of 3 W in continuous mode (CW). Radiation was performed using a 400-microm tapered fiber tip at an angle of approximately 5 degrees to the surface over a period of 30 seconds. The output power at the distal end of the tip was 0.6 W. The bacteria were then eluted through vibration and cultured on blood agar plates. The colony count reflected the antibacterial effect of laser radiation as a function of the layer thickness. RESULTS: A mean bacterial reduction of 74% was achieved even with a 500-microm thick slice. CONCLUSION: This investigation indicates that the diode laser radiation reduces the number of bacteria in deep layers of infected root canal wall dentin.

The effectiveness of an indicator gel in the detection of exposed dentine.

OBJECTIVES: To investigate the effectiveness of an indicator gel in revealing exposed dentine. METHODS: Teeth prepared into dentine and then stained with the indicator gel were sectioned for histological examination. RESULTS: The indicator gel was found to stain dentine and thin layers of enamel. CONCLUSION: The gel is suggested to be an effective indicator as an aid to acid etching and in the preparation of teeth for resin-bonded restorations.

[In-vitro research on the marginal adaptation of composites with the use of different dentin adhesives]. / In-vitro-Untersuchungen zur marginalen Adaptation von Komposits bei Anwendung verschiedener Dentinhaftmittel.

The aim of this investigation was the check and evaluation of 7 various dentin adhesives regarding their influence on the connection between dentin resp. enamel and composite filling. For that cylindrical cavities in dental crowns (enamel cavities) and roots (dentin cavities) were prepared and treated with dentin adhesives and composite materials. One part of the test teeth was subjected to loads storage in aqueous solution and thermocycling. The marginal adaptation of the composite filling was checked by means of the dye penetration test. The evaluation was made after cutting the teeth in the stereo microscope TECHNIVAL 2 (Carl Zeiss Jena) at 16-resp. 25 magnifications and defined criteria. The fillings in cavities bound by enamel exhibited a very good marginal adaptation of the composite. The location of the dentin cavity (crown or root dentin) had no significant influence on the fitting of the filling. A clear penetration of dye could be observed with the fillings in the dentin with and without adhesives, which considerably intensified after thermocycling. Best results with regard to the marginal adaptation were obtained with Scotchbond 2, Mirage-Bond and Cavex-Clearfil-Newbond. A restoration without a marginal gap was not possible.

[Comparative research on the treatment of exposed bi- or trifurcations]. / Vergleichende Untersuchungen der Bearbeitung der freiliegenden Bi- oder Trifurkation.

S.E.M. comparison studies between different systems for bi- and/or trifurcation treatment, such as special curettes, ultrasonics and rotary diamond burs, were examined at thirty molars. The result show specific rough root surfaces in relation to the individual system. Curettes leaves the roughest root surface.

[Dental treatment methods using the loupe]. / Zahnärztliche Behandlungsmethoden unter der Lupe.

The use of magnifying loupes in dentistry enhances the accuracy of working procedures. The precise fit of laboratory completed restorations can also be more easily controlled. Meticulous tasks such as caries excavation, the bonding technique, restorations, periodontics and surgical procedures are all greatly improved by clearer and better vision. Especially in the relatively new field of restorative cosmetic dentistry, with the adhesive technique, a high level of precise work is required. Caries excavation, enamel etching, bond application, as well as the finishing of restorations with special attention being paid to the enamel area and adjacent teeth are all difficult procedures, and are all greatly simplified by using magnifying loupes.

[Effectivity of ultrasonics by the root canal instrumentation]. / Die Effektivität von Ultraschall bei der Wurzelaufbereitung.

The investigative results showed that preparation of root canals is more effective with ultrasonic as compared to hand instrumentation. Areas like diverticula, canal enlargements or side canals were seen to be extremely clean. This is probably due to the effect of cavitation, implosion of small bubbles, the acceleration of minute particles and the formation of ultra sonic waves. The REM investigation showed no residual bacteria. The hand instrumented canals showed pulp remainders in the canal.

[Ultrasonic root planing. An alternative method versus hand instruments? An in vitro comparison and SEM study]. / Ultraschall-Wurzelglättung. Eine alternative Methode gegenüber Handinstrumenten? Ein in vitro-Vergleich und REM-Untersuchung.

This study showed no difference between the use of the "Piezon Master 400", using four different attachments as compared to the "Hu Friedy" Curettes as far the formation of grooves and scratch marks is concerned. Both root planing methods gave rise to a scalloped surface of the root cement. The ultrasonic root planing however showed a more discrete scalloped surface with very small tears and having a hammered appearance. Hand instrumentation showed much wider tears on the root surface structure.

[Test of Dentin Detector Gel color indicator--in vitro study]. / Prüfung des Farbindikators Dentin Detector Gel--Eine in-vitro-Studie.

A colour indicator, which was said to be suitable to detect artificially exposed dentine layers, was tested; these layers can be caused by preparations in conjunction with facette treatment, adhesive prosthetic dentistry, as well as smooth-face or dental neck filling therapy; these layers have to be covered before the application of adhesive techniques following the acid cauterization procedure.