Topographic representation of lower and upper teeth within the trigeminal sensory nuclei of adult cat as demonstrated by the transganglionic transport of horseradish peroxidase.

Transganglionic transport of horseradish peroxidase-wheat germ agglutinin conjugate (HRP-WGA) entrapped in hypoallergenic polyacrylamide gel was used to study the patterns of termination of primary afferents that innervate the lower and upper tooth pulps within the trigeminal sensory nuclear complex (TSNC). HRP injections were made into the inferior and superior alveolar nerves in order to compare the central projections of the whole nerve with those from tooth pulps. In addition, the relationship between the distribution of the trigeminothalamic tract cells and the projection sites of the tooth pulp afferents was investigated by injecting HRP into the posterior ventral thalamus. HRP-labeled tooth pulp afferent fibers innervating the lower and upper teeth projected to the subnucleus dorsalis (Vpd) of pars principalis, the rostrodorsomedial part (Vo.r) and nucleus dorsomedialis (Vo.dm) of pars oralis, the medial regions of pars interpolaris, and laminae I, II, and V of pars caudalis. Terminal fields of the lower tooth pulp afferents formed a rostrocaudally running, uninterrupted column from the midlevel of Vpd to the caudal tip of caudalis. In contrast, the column of termination of upper tooth pulp afferents was discontinuous at the Vpd/Vo.r transition, and ended at the more rostral level of the caudalis than that of the lower tooth pulp afferents. The representation of the lower and upper teeth in the TSNC was organized in a somatotopic fashion which varied from one subdivision to the next, although terminal zones of the inferior and superior alveolar nerves overlapped within the Vo.r, Vo.dm, and dorsomedial part of rostral pars interpolaris. The lower and upper teeth were represented in the Vpd, Vo.r, Vo.dm, medial region of pars interpolaris, and laminae I, II, and V, in a ventrodorsal or caudorostral, dorsoventral, lateromedial, dorsoventral, and mediolateral or dorsomedial-ventrolateral sequence, respectively. The smaller, more focal terminal areas of the teeth contrasted sharply with more extensive terminal fields of the alveolar nerves. The HRP injections within the thalamus indicated that neurons in Vpd, the caudal pars interpolaris, and laminae I/V of caudalis, which are subdivisions of TSNC that receive pulpal projections, sent their axons to the ipsilateral and contralateral posterior ventral thalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

Representation of upper and lower primary teeth in the trigeminal sensory nuclear complex in the young dog.

Transganglionic transport of horseradish peroxidase-wheat germ agglutinin conjugate entrapped in polyacrylamide gel was used to study the patterns of termination of primary afferents that innervate the upper and lower primary tooth pulps within the trigeminal sensory nuclear complex of the young dog. The lower and upper primary tooth pulp afferents projected to the subnucleus dorsalis of the principal nucleus, the rostrodorsomedial part and subnucleus dorsomedialis (Vo.dm) of the pars oralis, the nucleus of the intermediate plexus (Vi.ip) of the pars interpolaris, and laminae I, II and V of the caudalis. The lower and upper primary teeth were topographically represented in the Vo.dm, rostrocaudal mid-levels of Vi.ip, and in laminae I/V of the caudal levels of the pars caudalis, whereas an extensive overlapped projection was seen in other subdivisions.

Relationship between gingival health and dental caries in children aged 7-12 years.

The purpose of this study was to investigate the relationship between gingival health and dental caries in elementary school children in Japan. The subjects were 474 children aged 7 to 12 years who attended dental check-ups at an elementary school. The Oral Rating Index for Children, which consists of five categories (+2, +1, 0, -1, -2), was used to rate the findings of the gingival health examination. The dental examination was performed using the WHO caries diagnostic criteria for DMFT. Children were divided into three groups: a healthier group (H-group) made up of those scoring +2 (excellent) or +1 (good), an equivocal group (E-group) made up of those scoring 0, and a gingival less-healthy group (L-group) made up of those scoring -2 (very poor) or -1 (poor). Overall percentages for the H-group, E-group and L-group were 48.3%, 21.5% and 30.2%, respectively. The number in the L-group increased with increasing age. The mean scores of the DT and DMFT in the H-group were significantly lower than those in the L-group (p < 0.01 and p < 0.05, respectively). The results suggest that oral hygiene instruction should be given to children in order to motivate self-care, not only to avoid dental caries but also to prevent gingivitis.

Influence of parents' oral health behaviour on oral health status of their school children: an exploratory study employing a causal modelling technique.

OBJECTIVES: The aim of this study was to examine the simultaneous interrelationships between parents' oral health behaviour and the oral health status of their school children. SAMPLE AND METHODS: Subjects comprised 296 pairs of parents (mother or father) and their children at an elementary school in Hiroshima. The child's dental examination was performed using the World Health Organization (WHO) caries diagnostic criteria for decayed teeth (DT) and filled teeth (FT). The Oral Rating Index for Children (ORI-C) was used for the child's gingival health examination. Hiroshima University Dental Behavioural Inventory (HU-DBI) was used for the assessment of the parents' oral health behaviour. A parent-child behavioural model was tested by the linear structural relations (LISREL) programme. RESULTS: There was a significant correlation between DT and ORI-C (r = - 0.168; P < 0.01). Correlation was found between ORI-C and oral health behaviour in children (OHB-C) (r = 0.182; P < 0.01). OHB-C was significantly associated with the HU-DBI (r = 0.251; P < 0.001). The hypothesized model after some revisions was found to be consistent with the data (chi(2) = 1.3, d.f. = 6, P = 0.97; Goodness of Fit Index = 0.999). Parents' oral health behaviour affected their children's oral health behaviour (P < 0.001). Children's oral health behaviour affected their DT through its effect on gingival health level. Parents' oral health behaviour also had a significant direct effect on their children's DT (P < 0.05). Children's grade affected both DT and their oral health behaviour. CONCLUSIONS: Parents' oral health behaviour could influence their children's gingival health and dental caries directly and/or indirectly through its effect on children's oral health behaviour.

[A histopathological study on hypoplasia of the enamel].

The research on the development and injury of the hard tissue of teeth was studied by the pedodontic departments of nine dental schools. We participated in this research and studied histopathologically hypoplasia of the enamel in particular. There were seven selected teeth which had obvious hypoplasia of the enamel. We conducted observations with the naked eye, replica, general microscopy, polarized light microscopy, fluorescence microscopy, and microradiography. Moreover we studied to classify these cases into three types, that is to say, the injury factors of whole body, locality, and unknown origin. The results obtained were as follows. 1) As for the injury factors for the whole body, the bottom of the enamel defects were located corresponding to the incremental line of Retzius in the case of enamel hypoplasia of the deciduous teeth. Also enamel hypoplasia was located near the dentino-enamel junction corresponding to the surface of hypoplasia. 2) As for the injury factors with respect to locality, the bottom of enamel defects were located corresponding to the incremental line of Retzius. The dentino-enamel junction was irregular and discontinuous, still more a part of that area, and the dentin protruded or was exposed. 3) As for the injury factors of unknown origin, hypoplasia was located from the surface of the enamel but it did not spread. Also the hypoplasia of the enamel did not correspond to the incremental line of Retzius. 4) Five cases had fluorescence lines in enamel or dentin.