Computers in orthodontic practice: general considerations.
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Computers↗
Biomedical subjects
S R Freezer
Publications and source records attributed to S R Freezer.
Morphometry of neural structures in the mouse periodontal ligament mesial to the mandibular first molar.
The periodontal ligament mesial to the mandibular first molars of three mice was analysed stereologically between the alveolar crest and the tooth apex. Ultrathin tissue sections were collected at statistically predetermined intervals, 50 and 200 microns apart, examined in the TEM and quantified using standard point counting procedures (Gundersen et al. 1988). Findings include evidence that, in the mouse, some unmyelinated axons arise from myelinated axons and that anatomically discrete arrangements of unmyelinated axons occur in the apericytic wall sections of postcapillary-sized venules. Morphometric data indicate that unmyelinated axons constitute approximately 95 percent of all periodontal axons. The greatest relative proportion of myelinated axons is the bone third of the ligament, at depths between 600 and 800 microns, where the ratio of unmyelinated to myelinated axons is 5:1. Ultrastructurally, the ligament contains a variety of anatomically discrete neural structures in juxtaposition to periodontal blood vessels. These structures include nerve endings contiguous with K-cells, partially exposed terminal axons, preterminal and terminal axons protruding into the vessel lumina, and lamellated receptors. Mitochondria-rich terminals and fine nerve endings approximated pericytes in the walls of postcapillary-sized venules and arteriovenous anastomoses. Typically, these neural structures were characterised by the presence of an associated oxytalan fibre meshwork. This study also provides quantitative parameters for axon distribution within the ligament.
Animals↗
Statistical correlations between cells, blood vessels, oxytalan fibres and nerves in normal mouse molar periodontal ligament using transmission electron microscopy.
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Animals↗
A transmission electron-microscope stereological study of the blood vessels, oxytalan fibres and nerves of mouse-molar periodontal ligament.
Mandibular, mesiobuccal ligament was sectioned from the alveolar crest to the apex at predetermined levels. Data collected using standard point counting procedures was analysed for main effects due to animal, side of mouth, depth and zone across the ligament. Statistically-significant variations only occurred between different lateral thirds with the middle third containing the most oxytalan fibres and the bone third the greatest vascular and neural volumes. Stereology showed that the ligament was 3-7 times more vascular than other connective tissues. Eighty-eight per cent of the periodontal blood volume was enclosed in vessels with a mean lumenal diameter of 20.9 microns and characterized by a thin endothelial lining and few perivascular cells. These vessels had a surface density of 125.1 cm2/cm3. Oxytalan fibres had a length density of 1258 X 10(3) cm/cm3 and a mean caliper diameter of 0.7 micron. Furthermore, 78 per cent of fibres were adjacent to cells, 14 per cent within principal collagen fibres and 8 per cent in the walls of blood vessels. The length density of nerves within the ligament was 255.9 X 10(3) cm/cm3. Unmyelinated axons constituting 95 per cent of periodontal nerve fibres had a mean caliper diameter of 1.4 micron.
Animals↗