Radiographic interpretation of experimentally produced bony lesions.
Abstract Simulated bone-destroying lesions were created at the apices of two molars and four premolars in a sectioned mandible. All radiographic variables other than bone loss were strictly controlled. Results indicated that in the premolar region it is possible to detect radiographic change without involvement of the junctional or cortical bone, at least to a greater degree than in the molar region.
The effect of periapical rarefying osteitis on cortical and cancellous bone. A study comparing conventional radiographs with computed tomography.
OBJECTIVE
To determine whether erosion of the cortical plate is necessary for successful radiographic identification of periapical rarefying osteitis.


METHODS
Forty-two periapical osteitic lesions were diagnosed from periapical radiographs of 26 patients who were subsequently examined by cross-sectional computed tomography (CT). The relation of the lesions to the buccal and lingual cortical plates was determined and their size measured.


RESULTS
The 42 lesions varied in size from 2 - 10 mm. Thirty one (74%) lesions diagnosed on the periapical radiographs were limited on CT to the cancellous bone with no erosion of the cortical plates. The 11 lesions with cortical erosion were randomly located throughout the jaws. Erosion was due to either the eccentric buccal or lingual location of the tooth apex, large size (>6 mm) of the lesion or narrowness of the jaw.


CONCLUSIONS
Periapical lesions can be diagnosed from periapical radiographs while they are limited to the cancellous bone and before they have eroded the cortices.
Unidirectional hexagonal rare-earth disilicide nanowires on vicinal Si(100)-2×1
Rare-earth disilicide nanowires grown on vicinal Si(100) with a miscut of 2–2.5° toward the [110] azimuth at 600 °C were studied by scanning tunneling microscopy and compared with those grown on flat Si(001). In contrast to rare-earth disilicide nanowires grown on flat Si(100) surfaces, the nanowires grow unidirectionally along the [01̄1] direction of the vicinal Si(100) surface. Rare-earth disilicide nanowires form bundles composed of single nanowire units on both flat and vicinal surfaces. Yet, on the vicinal surface, the bundle width is comparable to the width of the terrace. The average nanowire length on the vicinal substrate is longer than that on the flat substrate. Scanning tunneling spectroscopy shows that the rare-earth disilicide nanowires have metallic properties.