摘要:

The intention of the study was to assess the differences in results obtained from creep and flow measurements of dental amalgams. Flow registers deformation during setting. Creep denotes the deformation of the set amalgam. The present study did not demonstrate a correlation between flow and creep, and creep is considered a more desirable parameter to include in a standard.

ISSN:0001-6357    

DOI:10.3109/00016357509004628

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The aim of the study was to investigate in commonly used experimental animals the pulpal wall and the dentin with special reference to the number and diameter of the dentinal tubules. The coronal dentin of a total of 26 permanent, intact teeth from rat, cat, dog and monkey was fractured experimentally. The calculations were based on the study of about 150 scanning electron microscope (SEM) photographs of fractured surfaces and of the pulp chamber wall. The number of dentinal tubules per unit area was calculated and the tubule diameter was measured at various distances from the pulp. The tubules were found to be widest at the pulpal wall, where the mean diameter ranged from 1.7 to 2.8μm, the highest value being found in monkey and the lowest in the incisors of rat. In the middle part of the dentin the mean diameter varied from 1.0 to 1.3 pm and at the periphery it was 0.6 to 0.9 pm. The largest number of tubules per unit area was found immediately incisal of the pulp horn and the smallest number cervically, near the enamel. At the pulpal wall the mean number of the tubules ranged from 50,000 to 90,000/mm2, in the middle of the dentin it was between 37,000 and 50,000/mm2and at the periphery it was between 10,000 and 25,000/mm2. In all species examined the dentinal tubules showed a straight course, except in incisors of rat, where local irregularities were seen. A comparison was also made between the species studied and homo with respect to the number and width of the dentinal tubules.

ISSN:0001-6357    

DOI:10.3109/00016357509004629

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The aim of the present study was to further investigate the plaque-reducing effect of a xylitol-containing chewing gum. Ninety-six dental students were divided randomly into three groups: a sucrose group (n = 32), a xylitol group (n = 36) and a control group (n = 28), using a sucrose-containing chewing gum, a xylitol-containing chewing gum, or no chewing gum, respectively, during a three-day experimental plaque growth period with restricted oral hygiene. The fresh weight of plaque collected in the xylitol group was 40 % lower than in the sucrose group, along with a significantly lower mean plaque index. The use of the xylitol chewing gum induced low invertase-like activity in plaque extra-cellular phase together with low carbohydrate content. These results concur to indicate advantageous effects through the use of a xylitol-containing chewing gum.

ISSN:0001-6357    

DOI:10.3109/00016357509004630

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The linkage between potentially teratogenic factors was studied in a material of 599 children with oral clefts and their matched controls. A method based on Yule's Q coefficient describing the degree of association between two dichotomous variables was applied. All factors studied (five groups of drugs taken by the mothers during early pregnancy, maternal influenza and fever) were significantly associated with the birth of children with clefts. The only factor whose association with clefts was explained by linkage to other factors was fever. In addition, the association between clefts and antipyretic analgesics other than salicylates could be partly explained by controlling the intake of salicylates. Although there was a strong association between influenza and consumption of salicylates, the correlation of neither of the two factors with oral clefts could be even partly explained by controlling the other. The method is considered suitable for epidemiological studies of congenital defects.

ISSN:0001-6357    

DOI:10.3109/00016357509004631

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

A longitudinal study was carried out in order to evaluate the caries incidence as affected by partial substitution of dietary sucrose (S) with xylitol (X), the effects of S-or X-containing chewing gums being compared during one year. The material comprised initially 102 young adults, predominantly dental and medical students, divided randomly into S-and X-groups. During the study 2 subjects were excluded, one due to lack of cooperation, the other not being allowed to enter the assigned S-group due to excessive caries prevalence. The subjects consumed 4.0 chewing gums per day in the S-group and 4.5 in the X-group. The frequency of sucrose intake was 4.2 times per day in the S-group, and 4.9 in the X-group. The caries incidence, assessed independently by clinical and radio-graphical means, expressed as the mean increment of decayed, missed and filled tooth surfaces, was 2.92 in the S-group, and—1.04 in the X-group. The corresponding values, when considering additionally the secondary caries reversals, were 3.76 in the S-group, and 0.33 in the X-group. The caries incidence was also expressed in combined quantitative and qualitative terms by considering in addition to the above parameters, also the changes in lesion size. The caries activity index thus calculated was 4.96 in the S-group, and 0.88 in the X-group. The results show a profound difference in the caries increment rate between the two experimental groups. The findings clearly indicate a therapeutic, caries inhibitory effect of xylitol.

ISSN:0001-6357    

DOI:10.3109/00016357509004632

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The mechanism by which tetracyclines affect the formation of dentin was studied by measuring the biosynthesis of collagen in the pulp. The material consisted of 160 rabbit pulps and 108 rat pulps. Collagen synthesis was determined by incubating pulps with [14C]proline and measuring the formation of non-dialyzable [14C]hydroxyproline. The activity of protocollagen proline hydroxylase was measured as the conversion of [14C]proline to [14C]hydroxyproline in a protocollagen substrate by the supernatant of a pulp homogenate. Inin vitroexperiments, oxytetracycline or demethylchlortetracycline inhibited collagen synthesis. Also, the activity of protocollagen proline hydroxylase extracted from rabbit pulps was decreased in the presence of tetracyclines. In both cases the inhibition was related to the concentration of tetracyclines and the inhibition could be preveted by addition of ferrous iron to the incubation. Inin vivostudies, injections of demethylchlortetracycline to rats inhibited collagen synthesis measuredin vitroand the activity of protocollagen proline hydroxylase in the incisor pulps. It was concluded that this effect may be specific to collagen synthesis and the effect may be through chelation of ferrous iron, a cofactor of protocollagen proline hydroxylase. Consequently, the mineralization disturbances in developing teeth during tetracycline therapy may be partly due to a decreased formation of the organic matrix of dentin.

ISSN:0001-6357    

DOI:10.3109/00016357509004633

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The aim of the study was to observe pulpal collagen synthesis in response to trauma and to glucocorticoid medication. The material consisted of 290 rabbit pulps and 76 human premolar pulps. Collagen synthesis was determined by incubating whole pulps in a medium containing [14C]proline. and measuring the formation of [14C]-hydroxyproline. The effect of glucocorticoids was studiedin vitrousing rabbit pulps. Hydrocortisone and dexamethasone inhibited collagen synthesis, whereas prednisolone had no marked effect. Hydrocortisone was found to inhibit the synthesis of [14C]hydroxyproline in neutral salt soluble and insoluble non-dialyzable collagen fractions. [14C]hydroxyproline in the dialyzable fraction was increased, suggesting that hydrocortisone increased collagen degradation. In the human material, premolar pulps were experimentally exposed and then medicated with capping agents. The contralateral teeth were exposed and capped with other capping materials, in some cases they were left as intact controls. The exposure led to an increase in the collagen synthesis as indicated by increased [14C]hydroxyproline formation and elevated protocollagen proline hydroxylase activity in the pulp. This enzyme activity was suppressed in pulps capped with a glucocorticoid paste. In addition, the collagen synthesis rate was lower in pulps treated with another glucocorticoid containing compound, when compared to pulps capped with a calcium hydroxide preparation.

ISSN:0001-6357    

DOI:10.3109/00016357509004634

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The present study includes a reexamination of 10 patients who, two years ago received complete upper and lower denture treatment to eliminate an existing denture stomatitis. Clinical healing of the denture stomatitis was obtained only in one patient, whereas the remaining nine patients still displayed an obvious denture stomatitis. Biopsies were taken from the palatal mucosa and examined histologically, microradiographically, and by electron microscopy. The results of these examination indicated that, in denture stomatitis there is a reduced thickness of the epithelium, an absence of a stratum corneum, a markedly widened intercellular space, especially in the stratum basale, and an intense infiltration of inflammatory cells, plasma cells and lymphocytes in the connective tissue, as well as in the epithelium. These changes are characteristic features of an inflammatory process, and similar to the changes which occur, for example, in chronic, marginal gingivitis. The composition of the inffammatory infiltrate suggested that, in denture stomatitis, immunological phenomena influence the pattern of the tissue reaction.

ISSN:0001-6357    

DOI:10.3109/00016357509004635

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor