A Cr4+:forsterite laser for intracavity absorption spectroscopy in the spectral range of 1.2-1.4 µm.

We present a broadband cw Cr4+:forsterite laser operating at room temperature with a lasing threshold of 0.8 W that is tunable in the spectral range from 7246 to 8361 cm-1 (1196-1380 nm). This laser is applied for highly sensitive measurements of gaseous absorption inside the cavity. The maximum sensitivity demonstrated in the experiment corresponds to an effective absorption path length of Leff = 2500 km. The spectral bandwidth of laser emission varies from 3 to 150 cm-1 depending on the laser pulse duration, enabling broadband multi-component absorption measurements. We demonstrate sensitive detection of various species (with estimated detection limits), such as H2O (25 ppt), O2 (3 ppm), CO2 (150 ppb), CH4 (2 ppb), HCl (6 ppb) and HF (2 ppt) using lab-scale absorption lengths of about one meter.

Incidence of cholesterol in periapical biopsies among adolescent and elderly patients.

INTRODUCTION: Cholesterol clefts are common histologic findings in periapical biopsies; they have a reported incidence in periapical periodontitis of up to 44%. Cholesterol crystals are also recognized in advanced atherosclerotic plaques in humans. Male sex, genetic abnormalities, and age have been associated with advanced atherosclerotic lesions. Among these nonmodifiable risk factors, age is the most dominant. The aim of the study was to evaluate if age is also linked to cholesterol deposition in periapical periodontitis. METHODS: The database of biopsy reports obtained between 2006 and 2009 was searched for specimens diagnosed as radicular cysts or periapical granulomas. Only data relating to biopsies obtained from adolescent (13-21 years old) and elderly (over 60 years old) patients were selected. The biopsies were examined by a pathologist under a light microscope (Zeiss, Jena, Germany) at magnifications of 40×-200×. The available material was scanned for the presence of cholesterol clefts and foamy cells in radicular cysts and granulomas. RESULTS: A total of 41 specimens were collected in the adolescent group and 48 specimens in the elderly group over a 4-year period. A higher incidence of cholesterol was found in the elderly group compared with that in the adolescent group (odds ratio = 6.857). CONCLUSIONS: The highly significant incidence of cholesterol deposits in periapical biopsies among elderly patients may be a possible cause for the lack of repair. The mechanism for cholesterol accumulation is probably similar to the process leading to atherosclerosis and coronary artery disease. Statin administration may be advantageous for the treatment of persistent lesions. A clinician should be aware of the risk for persistent lesions after endodontic treatment in elderly patients.

The effect of dentin on the pulp tissue dissolution capacity of sodium hypochlorite and calcium hydroxide.

INTRODUCTION: Sodium hypochlorite (NaOCl) and calcium hydroxide (Ca[OH]2) have tissue dissolution capacity. The aim of this study was to evaluate the potential effect of dentin on their tissue dissolution capacity in a novel dentin model. METHODS: Dentin models were prepared from 25 freshly extracted human molar teeth; the crowns were separated from the roots, and a rectangular inner shape was prepared. Pulp tissue samples adjusted to similar weights of 6.5 ± 0.2 mg were randomly divided into 6 groups: NaOCl groups in test tubes or dentin models for 1 hour, Ca(OH)2 groups in test tubes or dentin models for 1 week, and control groups saline in test tubes or dentin models for 1 week. The final weights after the experimental period were checked and compared with the initial weights. The differences were statistically analyzed. RESULTS: The tissue dissolution capacity of Ca(OH)2 was affected by the presence of dentin. Similarly, NaOCl lost its effect on the pulp tissue after incubation in dentin. Comparison between all test groups showed highly significant differences (P < .001). CONCLUSIONS: Dentin has a detrimental effect on the ability of NaOCl and Ca(OH)2 to dissolve pulp tissue. The dentin model appears to be an efficient tool for the study of interactions between local endodontic medicaments, dentin, and pulp tissue.

Multicolor diode-pumped upconversion fiber laser.

We present a new method to control the power of individual spectral components of a multicolor laser by mirrors with variable air gaps and by a composite resonator configuration. We demonstrate a Pr/Yb-ZBLAN fiber laser with arbitrary spectral composition of three simultaneously emitted components at 492 nm, 520 nm, and 635 nm. With 100 mW pump power at 850 nm launched into the fiber, the total laser output exceeds 10 mW.

Aggressive periodontitis among young Israeli army personnel.

BACKGROUND: The aim of this study was to assess the prevalence of aggressive periodontitis among young Israeli army recruits and to evaluate its association with smoking habits and ethnic origin. METHODS: The study population consisted of 642 young army recruits (562 men [87.5%] and 80 women [12.5%]), aged 18 to 30 years (average: 19.6 +/- 1.6 years), who arrived at a military dental clinic for dental examinations between January and December 2004. Subjects filled out a questionnaire regarding their ethnic origin and family periodontal history, followed by radiographs and a clinical periodontal examination of four first molars and eight incisors. RESULTS: Aggressive periodontitis was found in 5.9% of the subjects (4.3% localized and 1.6% generalized). At least one site with a probing depth > or =5 mm was found in 20.1% of the subjects. A radiographic distance between crestal bone height and the cemento-enamel junction >3 mm was found in 43 (6.7%) subjects. Current smokers (39.9%) (P = 0.03) and subjects of North African origin (P <0.0001) correlated with a high prevalence of aggressive periodontitis. CONCLUSION: A relatively high prevalence of aggressive periodontitis was found in young Israeli army recruits, which was particularly associated with smoking and ethnic origin.