Number and size-spectra of myelinated nerve fibers of human premolars

Nair, Prashant; Luder, Hans U.; Schroeder, Hubert E.

doi:10.1007/bf00186979

Cited by 13 publications

(9 citation statements)

References 23 publications

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“…Our results concerning the small number of large-sized axons find an echo in the abovementions study of human premolar by Nair et al 8) which contents that large-sized nerve fibers account by about 10% of the myelinated nerve by any teeth. In the same way, Loescher and Holland11) reported on the periodontal ligament in the cats, mention a percentage of large-sized axon ranging form 14 to 20%.…”

Section: Discussionsupporting

confidence: 77%

Morphometric Difference in the Human Maxillary Nerve Fibers between Dentulous and Edentulous Jaw Subjects

Ishikawa

Ezure

Goto

et al. 2005

Okajimas Folia Anat. Jpn.

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Summary: This study was conducted to quantify the change in the number and size of myelinated nerve fibers of the maxillary nerve with tooth loss in humans. We carried out a morphometric analysis to compare the number and size of myelinated nerve fibers in the human maxillary nerve between four dentulous and four edentulous jaw cases. Our results indicated that the number of axons decreased by approximately 13,000 with tooth loss. The average size of axons remained unchanged, but there was a change in the fiber size distribution, namely the loss of a large number of smallsized axons was accompanied by the total disappearance of small number of large-sized axons.

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Section: Discussionsupporting

confidence: 77%

Morphometric Difference in the Human Maxillary Nerve Fibers between Dentulous and Edentulous Jaw Subjects

Ishikawa

Ezure

Goto

et al. 2005

Okajimas Folia Anat. Jpn.

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“…The data from the present study indicate that the composition of apical nerves of the adult rat molar is similar to that in mature teeth of other well-studied species. In both cat and human teeth, large numbers of unmyelinated and myelinated fibers traverse the root apex at ratios varying from 2:l to 5:l Karlsson, 1974, 1977;Johnsen and Johns, 1978;Fried and Hildebrand, 1981;Holland and Robinson, 1983;Johnsen et al, 1983;Nair et al, 1992). Our finding of a mean ratio of 3 5 1 unmye1inated:myelinated axons in the adult rat molar is within this range.…”

Section: Discussionsupporting

confidence: 58%

Quantitative study of the apical nerve fibers of adult and juvenile rat molars

1994

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The rat molar has become an important model for studies of interactions between nerves and the pulp-dentin complex, yet there is only limited quantitative information on the number and size distribution of axons entering the roots of this tooth. This study was undertaken to provide such a detailed characterization of the apical innervation of the rat molar. An additional objective was to compare the apical nerve composition of young, recently erupted rat molars with that of mature teeth in order to determine whether there is ongoing maturation of the innervation after the teeth have attained functional occlusion. A complete census was made of the nerve fibers entering the roots of both mature and recently erupted juvenile mandibular first molars in Sprague-Dawley rats. Each of the four roots of the first molars was processed for electron microscopy of thin sections near the apex. The majority of intradental nerve fibers entered the molar via the two larger (mesial and distal) roots. Within the apical root pulp, most, but not all, axons occurred within well-defined fascicles associated with blood vessels. Molars from adult animals (age 4 months) had a mean total of 232 (S.D. = 49, N = 7 teeth) myelinated fibers and 806 (S.D. = 143) unmyelinated axons entering the four roots. Fibers exceeding the A delta size range (circumference > or = 19 microns) accounted for only 4% of the myelinated axons at the apex. Molars from juvenile animals (age 4 weeks) had fewer myelinated fibers (mean 176, S.D. 18, N = 8), but more unmyelinated axons (mean 1,174, S.D. 160) than adults. The mean ratio of unmyelinated axons to myelinated axons was 6.6:1 for juveniles compared to 3.5:1 for adults. Juvenile teeth contained no myelinated fibers that exceeded 19 microns in circumference. These results indicate that the innervation of the rat molar resembles that of teeth of non-rodent mammals in that (1) innervation density is high, (2) there is a high ratio of unmyelinated axons, and (3) most of the myelinated fibers are of thin caliber. Furthermore, it appears that after the molar erupts, maturation of the nerve fiber composition continues with processes that include both a marked decrease in the number of unmyelinated axons and an increase in the number and size heterogeneity of myelinated fibers.

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“…Data on myelinated tooth-axons have been published previously (Nair et al 1992). Here we report the number and size spectra of non-myelinated axons entering the apical radicular pulp of human premolars.…”

Section: Discussionmentioning

confidence: 99%

“…The material used for this study formed part of a larger collection of specimens prepared for a previous investigation to quantitate the myelinated axons of healthy human premolars removed for orthodontic reasons (Nair et al 1992). The methods used can be summarized as follows: (1) immediately after extraction the teeth were fixed by immersion in a half-strength Karnovsky's (1965) solution;…”

Section: Tissue Processingmentioning

confidence: 99%

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Number and size spectra of non-myelinated axons of human premolars

Nair

Schroeder

1995

Anat Embryol

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The aim of this study was to determine the number and size of apical non-myelinated (C) axons of healthy human premolars. The material was derived from a large collection of specimens prepared for a previous quantitative investigation on the myelinated (A) axons of human premolars. A total of 16 teeth (six maxillary first and five each of mandibular first and second premolars), removed from adolescents for orthodontic reasons, were used. Root discs of about 0.6 mm thickness were prepared at about 2 mm cervical to the root apex and processed for light and electron microscopy. The number of non-myelinated axons was determined by taking a total census of such fibres that could be identified and reconstructed by standardized composite electron micrographs from each root disc. The measurement of axons was done on a statistically representative sample of axons (n = 1810) using an electronic image processing unit. The 16 teeth had an average of 2000 +/- 1023 non-myelinated axons at the juxta-apical level (range 534-3912). The average diameter of the non-myelinated axons was found to be 0.5 +/- 0.4 microns (range 0.05-2.4 microns).

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Number and size-spectra of myelinated nerve fibers of human premolars

Cited by 13 publications

References 23 publications

Morphometric Difference in the Human Maxillary Nerve Fibers between Dentulous and Edentulous Jaw Subjects

Morphometric Difference in the Human Maxillary Nerve Fibers between Dentulous and Edentulous Jaw Subjects

Quantitative study of the apical nerve fibers of adult and juvenile rat molars

Number and size spectra of non-myelinated axons of human premolars

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