فهرست مطالب norbert gutknecht

An increase in dentine thickness could result in an inadequate depth of laser energy penetration. This study aimed to evaluate the effect of a 940 nm laser on Enterococcus faecalis through varying thicknesses of human root dentin slices.

Thirty-five dentin slices of root dentin with thicknesses ranging between 500 and 3000 μm were produced. Six experimental groups (500, 1000, 1500, 2000, 2500, and 3000 μm (n=5 each) were lased and the seventh, non-lased group served as the positive control with a dentine thickness of 2000 μm. The slices were inoculated with 2 μL of E. faecalis suspension of 1.5 × 108E. faecaliscells/mL. All the lased slices were lased from the opposing side of the inoculation. A non-initiated 200 μm bare end fibre at the power of 1 W, in a continuous wave was used. Four doses of laser irradiation of 5 seconds with a side to side movement with the tip held at a 5º angle to the dentine slice were performed. The colony-forming units of E. faecalis were determined and the bacterial photobiomodulation effect analysed using one-way ANOVA with a Bonferroni and Holm post hoc test at a significance level of P > 0.05.

There were statistical differences between the dentin slices of 500, 1000, and 1500 μm treated with the laser compared to the positive control (P < 0.01). However, there were no statistical differences between the lased 2000 and 2500 μm slices compared to the positive control. There was significantly more photobiomodulation of the E. faecalis for the dentine slices of 3000 μm than the positive control (P < 0.01).

Laser treatment through dentine slices of 2000 μm and thinner significantly reduced bacterial growth. The photobiomodulation effects started to occur in dentine slices thicker than 2500 μm compared to the positive control.

The tooth root surfaces are modified by different agents for better removal of the smear layer, formation of fibrin clots and attachment of blood cells. This in vitro study compared removal of the smear layer, formation of fibrin clots and attachment of blood cells after exposing periodontally compromised root surfaces to ER:YAG and CO2 laser beams.

Eighteen dentin block samples were prepared from freshly extracted periodontally compromised teeth that were deemed hopeless, and divided into 3 groups; exposed to Er:YAG laser beams, exposed to CO2 laser beams and the control group. The samples were evaluated using scanning electron microscopy and micrographs were taken. Smear layer removal and blood cell attachment were scored. Data were analyzed with SPSS using Kruskal-Wallis and Mann-Whitney tests.

In the Er:YAG laser group, the smear layer was removed completely. In the specimens exposed to blood, better fibrin clot formation and blood cell attachment were observed in the Er:YAG laser group. In the CO2 laser group, the smear layer was also removed; however, there were no significant differences between the CO2 laser and control groups in fibrin clot formation and blood cell attachment.

Application of Er:YAG laser to the root dentin appears to result in the formation of a suitable surface for fibrin clot formation and blood cell attachment. Further clinical studies are necessary to support these results.

Sodium hypochlorite (NaOCl) irrigation is critical for the success of endodontic treatment and several agitation techniques have been developed to improve the efficacy of this irrigation. Using a combination of contrast medium and radiographic examination, this study evaluated NaOCl extrusion during agitation of irrigant. Development of pressure, which may result in apical extrusion of the irrigant, has been described during laser-activated irrigation (LAI) and passive ultrasonic irrigation (PUI).
Methods and Materials: We examined 40 single root canals categorized as having open apices with apical lesions in 40 patients. For the final irrigation, the teeth were irrigated with a mixture of radiopaque contrast medium and 2.5% NaOCl in solution. The solution was activated for 60 sec in both groups [the Er, Cr: YSGG laser group (n=20) and the ultrasonic group (n=20)]. The teeth were imaged subsequently using radiography for the evaluation of contrast extrusion.
Radiopaque contrast medium was absent from the periapical tissues in all cases.
Use of LAI or PUI appears to be safe as used currently in endodontic treatment.

Side effects related to antibiotic therapy for peri-implantitis are rare in laser therapy (LT); therefore, the aim of this study was to evaluate the effectiveness of LT and photodynamic therapy (PDT) on patients with primary peri-implantitis.
In this randomized clinical trial, 40 implants presenting primary peri-implantitis in 20 patients with a mean age of 52.6 years old were included using the simple sampling technique. Periodontal treatment comprising scaling and root planing (SRP) was accomplished for the whole mouth while mechanical debridement with titanium curettes and air polishing with sodium bicarbonate powder was accomplished around the implants. The implants were randomly divided into two groups and treated with LT (control) and PDT (test). The clinical indices were measured at baseline, 6 weeks and 3 months after treatment. Real-time polymerase chain reaction (PCR) was used for analysis of microbial samples at baseline and 3-month follow-up. Data were analyzed with SPSS 20, using repeated-measures analysis of variance (ANOVA) and Friedman’s and Mann-Whitney tests (α = 0.05).
Both groups showed statistically significant improvements in terms of bleeding on probing (P 0.05). The number of Aggregatibacter actinomycetemcomitans (P = 0.022), Tannerella forsythia (P = 0.038) and Porphyromonas gingivalis (P = 0.05) in the test group and Porphyromonas gingivalis (P = 0.015) in the control group significantly decreased.
The results suggested that LT and PDT have significant short-term benefits in the treatment of primary peri-implantitis.