Dental and periodontal status and risk for progression of carotid atherosclerosis: the inflammation and carotid artery risk for atherosclerosis study dental substudy.

BACKGROUND AND PURPOSE: Dental and periodontal disease are potentially involved in the pathogenesis of atherosclerosis. We investigated whether dental and periodontal status is associated with the presence and future progression of carotid stenosis. METHODS: We randomly selected 411 of 1268 participants from the prospective Inflammation and Carotid Artery Risk for Atherosclerosis Study and evaluated dental and periodontal status and oral hygiene at baseline measuring three World Health Organization-validated indices: DMFT (decayed, missing, filled teeth), SLI (Silness-Löe Index), and CPITN (community periodontal index for treatment needs), respectively. The degree of carotid stenosis was measured by duplex ultrasound at baseline and after median 7.5 months (range=6 to 9 months) to identify patients with progressive carotid stenosis. RESULTS: DMFT (P<0.01), SLI (P=0.048), CPITN (P=0.007), and edentulousness (P=0.007) were associated with the baseline degree of carotid stenosis. Atherosclerosis progression was observed in 48 of 411 patients (11.7%). DMFT (adjusted odds ratio [OR]=1.11, 95% CI=1.01 to 1.22, P=0.032) and SLI (adjusted OR=1.77, 95% CI=1.09 to 2.79, P=0.021), but not CPITN (adjusted OR=1.51, 95% CI=0.89 to 2.45, P=0.16) were significant predictors of disease progression, irrespective of traditional cardiovascular risk factors and the baseline degree of stenosis. Edentulous patients had a significantly increased risk for disease progression as compared with patients with teeth (adjusted OR=2.10, 95% CI=1.06 to 4.16, P=0.33). CONCLUSIONS: Dental status, oral hygiene, and particularly tooth loss are associated with the degree of carotid stenosis and predict future progression of the disease.

Innovative wavelengths in endodontic treatment.

BACKGROUND AND OBJECTIVES: The sanitation of the root canal system and the adjacent dentin has always been a key requirement for successful endodontics. In recent years, various laser systems have provided a major contribution to this aim, namely the Nd:YAG-, the 810 nm Diode-, the Er:YAG-, and the Er,Cr:YSGG laser. Numerous studies could prove their efficiency within the endodontic procedure. Recently, two new wavelengths have been introduced to the field of oral laser applications: The KTP laser emitting at 532 nm and the 980 nm diode laser. The present in vitro investigation was performed to evaluate the effects of these laser systems focusing on their antibacterial effect in deep layers of dentin and their impact on the root canal dentin. STUDY DESIGN/MATERIALS AND METHODS: Two-hundred slices of root dentin with a thickness of 1 mm were obtained by longitudinal cuts of freshly extracted human premolars. The samples were steam sterilized and subsequently inoculated with a suspension of either Escherichia coli or Enterococcus faecalis. After the incubation, the samples were randomly assigned to the two different laser systems tested. Each laser group consisted of two different operational settings and a control. The dentinal samples underwent "indirect" laser irradiation through the dentin from the bacteria-free side and were then subjected to a classical quantitative microbiologic evaluation. To assess the temperature increase during the irradiation procedure, additional measurements were carried out using a thermocouple. To assess the impacts on the root canal walls, 20 additional samples underwent laser irradiation at two different settings and were subjected to scanning electron microscopy. RESULTS: Microbiology indicated that both laser systems were capable of significant reductions in both test strains. At an effective output power of 1 W, E. coli was reduced by at least 3 log steps in most of the samples by the tested wavelengths, with the best results for the KTP laser showing complete eradication of E. coli in 75% of the samples. E. faecalis, a stubborn invader of the root canal, showed minor changes in bacterial count at 1 W. Using the higher setting of 1.5 W, significant reductions of E. coli were again observed with both laser systems, where the lasers were capable of complete eradication of E. faecalis to a significant extent. There was no significant relation between the temperature increase and the bactericidal effect. CONCLUSIONS: The present study demonstrates that both wavelengths investigated could be suitable for the disinfection of even the deeper layers of dentin and equal the results achieved by established wavelengths in state-of-the-art endodontics.

Bactericidal effect of different laser systems in the deep layers of dentin.

BACKGROUND AND OBJECTIVES: In recent years, various laser systems have gained importance in the field of laser-assisted endodontics, namely the Nd:YAG, the diode, the Er:YAG, and the Er,Cr:YSGG laser. Individual studies have been carried out so far, focusing on the respective wavelength, its specific bactericidal capabilities, and potential usefulness is root-canal disinfection. The present in vitro investigation however, was performed to compare the microbicidal effect of these laser systems under standardized conditions and to draw a conclusion upon their relative effectiveness in the deep layers of dentin. STUDY DESIGN/MATERIALS AND METHODS: In total, 360 slices of root dentin with a thickness of 1 mm were obtained by longitudinal cuts of freshly extracted human premolars. The samples were steam sterilized and subsequently inoculated with a suspension of either Escherichia coli or Enterococcus faecalis. After the incubation, the samples were randomly assigned to the four different laser systems tested. Each laser group consisted of two different operational settings and a control. The dentinal samples underwent "indirect" laser irradiation through the dentin from the bacteria-free side and were then subjected to a classical quantitative microbiologic evaluation. To assess the temperature increase during the irradiation procedure, additional measurements were carried out using a thermocouple. RESULTS: Microbiology indicated that all laser systems were capable of significant reductions in both test strains. At an effective output power of 1 W, E. coli was reduced by at least three log steps in most of the samples by the tested wavelengths, with the best results for the Er:YAG laser showing complete eradication of E. coli in 75% of the samples. E. faecalis, a stubborn invader of the root canal, showed minor changes in bacterial count at 1 W. Using the higher setting of 1.5 W, significant reductions of E. coli were again observed with all laser systems, where only the diode and the Er:YAG laser were capable of complete eradication of E. faecalis to a significant extent. There was no significant relation between the temperature increase and the bactericidal effect. CONCLUSIONS: The present study demonstrates that all the wavelengths investigated are suitable for the disinfection of even the deeper layers of dentin and may prove to constitute valuable tools in state-of-the-art endodontics.

The Er:YAG laser in endodontics: results of an in vitro study.

BACKGROUND AND OBJECTIVE: Until recently, the main field of Er:YAG laser application was the removal of dental hard substances within the scope of cavity preparation. Nowadays, several new delivery-systems are available, permitting the application of the Er:YAG laser in endodontics. The aim of the present study was to assess the effects of Er:YAG laser irradiation on root canals in vitro. STUDY DESIGN/MATERIALS AND METHODS: For this purpose, 220 extracted human teeth were endodontically processed and subsequently irradiated at different settings using an Er:YAG laser imitating in vivo irradiation procedures. The teeth were then subdivided into three groups and subjected to bacteriological evaluations, scanning electron microscopy, and temperature measurements. RESULTS: The bacteriological evaluation revealed a decisive bactericidal effect of the Er:YAG laser in the root canal. The bactericidal effect was dependent on the applied output power and specific for the different species of bacteria investigated. Scanning electron microscopy showed discrete removal of dentine from the root canal walls. The temperature rise during irradiation was moderate when standardized power settings were used. CONCLUSION: The investigations indicate that the Er:YAG laser is a suitable tool for the elimination of bacteria in root canals under in vitro conditions.