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Biomedical subjects

L Shapira

Publications and source records attributed to L Shapira.

66 records · Page 4Linked to original sources
PubMed1991

Superoxide formation and chemiluminescence of peripheral polymorphonuclear leukocytes in rapidly progressive periodontitis patients.

Previous studies have indicated that in certain types of chronic inflammatory periodontal diseases, polymorphonuclear leucocytes (PMN) functions are impaired. In view of the damage oxygen free radicals may cause to the periodontal tissues, the present study focussed on superoxide (SO) formation and luminol-dependent chemiluminescence (LDCL) by peripheral PMN cells in rapidly progressive periodontitis patients (RPP). PMN cell preparations were stimulated by either opsonized bacteria or phorbol myristate acetate (PMA). The results indicate that PMN cells from RPP patients, stimulated by opsonized bacteria, have significantly enhanced SO formation and LDCL response as compared to healthy subjects. The hyperactivity was cell-associated. In the presence of PMA, no significant differences were detected between the groups. The results suggest that PMN cells from RPP patients are functionally activated, and produce elevated levels of oxygen radicals. These oxygen radicals may play a role in the pathogenesis of RPP.

Adolescent↗
PubMed1991

Effect of glycyrrhizin-containing toothpaste on dental plaque reduction and gingival health in humans. A pilot study.

Glycyrrhizin, the main saponin of licorice, a surfactant producing aqueous gel, was tested for its effect on gingival health, as a supplemental agent in a toothpaste. 40 male and female volunteers brushed their teeth twice daily, with a toothpaste containing 0.25% and 0.50% glycyrrhizin, or a control toothpaste, respectively. All 3 toothpastes contained sodium lauryl sulfate as detergent. The subjects of the 3 groups were examined at days 0, 7, 14, 28, 35 and 42 for plaque, gingival and bleeding indices. The examiner was unaware of subject assignment. None of the brushing regimens with the experimental toothpastes induced significant changes in the examined indices, that were distinct from those observed with the control toothpaste. The decrease (insignificant) in the indices of the study period from 0 to 14 days may be considered as an increased oral hygiene awareness by the subjects examined. Possible explanations for the lack of efficiency in improvement of plaque, gingival and bleeding indices, may have been an insufficient glycyrrhizin concentration and/or chemical incompatibility in a toothpaste containing a mixture of an anionic detergent and an organic antibacterial surface agent.

Adult↗
PubMed1991

Enamel softening with Coca-Cola and rehardening with milk or saliva.

Rehardening effects by cow's milk and by secreted saliva were investigated, in situ, following softening of human enamel with an acidic beverage (Coca-Cola). Volunteers wearing orthodontic removable appliances participated in the study. The intra-oral test was chosen for measuring microhardness of enamel slabs inserted into the dental appliance. The softening and the rehardening degrees were defined as the alterations between initial- and experimental-microhardness value at the enamel surface. In addition, SEM photos were prepared from the initial and experimental stages. Exposure of enamel slabs to the acidic beverage during 1 hour had a softening effect as expressed by the hardness decrease and visualized by the SEM photo. Rehardening effects following milk or saliva exposures respectively were evident, presumably due to deposited organic and mineral material on the enamel surface.

Adult↗
PubMed1989

Effect of prenatal and postnatal fluoride on the human deciduous dentition. A literature review.

Fluoride passes from the mother to fetal teeth. Much of the fluoride is taken up in secretory enamel, probably by the forming mineral apatite crystals. Some is retained with residual proteins. The low concentration of fluoride in the inner enamel is incorporated mainly during the secretory stage, while the enhanced concentration in the surface enamel is produced during the much longer maturation stage. Mature, hard enamel is generally absent during fetal life. The clinical question is whether prenatal fluoride imparts an additional benefit to the universally accepted effect of postnatal fluoride. In general, surface enamel fluoride levels of deciduous teeth increase with increasing pre- and postnatal fluoride administration. A consistent level of caries protection has been reported with pre- and postnatal administration of fluoride unrelated to the acquisition of fluoride in the surface enamel. Many children develop enamel opacities in their deciduous dentition related by various factors to enamel mineralization disturbances in drinking water areas even low in fluoride. Accumulation of fluoride due to an increased fluoride intake is a feature of fluorosed enamel in the deciduous as well as permanent dentition. The resulting mature fluorosed enamel retains a relatively high proportion of immature matrix proteins onto the crystal surface. The degree of fluorosis of the deciduous dentition is less compared with that of the permanent dentition, due probably to a partial protection afforded by the maternal loss of fluoride, formerly known as the "placental barrier".

Dental Enamel↗
PubMed1987

Changes in mineral distribution and concentration during enamel development in the deciduous human maxillary and mandibular teeth.

The present study describes the detailed changes in mineral concentration in developing human enamel across the different stages of development from early formation to maturation in the human maxillary and mandibular deciduous teeth. The results indicate a stage in the development of enamel in each of the deciduous human teeth in which the tissue becomes porous due to a loss of matrix protein which is subsequently replaced by mineral during the maturation process with the enamel finally becoming fully mineralized and hard. The time of appearance of this porous stage varies in the different deciduous teeth. The importance of this stage with regards to enamel susceptibility to metabolic influences is discussed.

Aging↗
PubMed1987

Pattern of mineral uptake in the developing human deciduous enamel.

The present study describes the detailed changes in mineral concentration in developing human enamel across the different stages of development from early formation to maturation. The results indicate a stage in the development of deciduous human incisor enamel in which the tissue becomes porous because of a loss of matrix protein, which is subsequently replaced by mineral during the maturation process, with the enamel finally becoming fully mineralized and hard. The importance of this stage with regard to enamel susceptibility to metabolic influences is discussed.

Amelogenesis↗
PubMedDate not supplied

Effect of amine fluoride subgingival irrigation on periodontally diseased sites.

Amine fluoride gel, a surfactant and bactericidal compound was tested for irrigation of periodontal sites in inflammatory periodontal disease. Eight volunteer-patients who had at least 4 sites with probing depths of 6 mm or more in two different quadrants participated in the study. The start of the study was preceded by supragingival scaling. At the selected sites clinical (PI, GI, BOP, probing attachment) and microbial examinations (percentage motile rods and spirochetes) were performed at baseline, 30, 60 and 9 days. Irrigation with AmF gel and saline was performed at experimental and control sites twice weekly during one month. The mean Plaque Index, bleeding on probing and percentage mobile rods and spirochetes, at baseline, were not significantly different between the experimental and control groups, where as the mean gingival index and probing attachment were significantly different. There were decreases in the Plaque and Gingival Indexes, bleeding on probing, percentage motile rods and spirochetes and gain in probing attachment in both experimental and control groups during the test period of 60 days. However, these improvements from baseline values to the periods of 30, 60 and 90 days between the treatment and control groups were not significant. Although mean improvements of the parameters examined were greater in the experimental group, this was probably due to higher baseline values in this group.

Adult↗
PubMedDate not supplied

The relationship between alveolar bone loss and proximal caries in children: prevalence and microbiology.

The present study describes the prevalence of alveolar bone loss (ABL) in children in relation to caries, contact and space loss. In addition, the microbial composition of the subgingival plaque of 20 sites, from 5 children, is presented. Bite-wing radiographs from 500 children were examined. ABL was evident in: 99 sites from 60 children; > 1 site in 27 children; the maxilla only in 34 children; the mandible only in 17 children; both arches in 9 children; 37 sites with no caries; 4.9 percent of all sites with proximal caries; 15.8 percent of all sites with contact loss; and 20.5 percent of all sites with mesial drift. Anaerobic bacteria were cultured from all 20 sites. No significant differences in the percentages of colony forming units of Actinobacillus actinomycetemcomitans and black pigmented Bacteroides were found among sites with/without bone loss, with/without caries or probing depths smaller/equal or larger than 2.5 mm.

Aggregatibacter actinomycetemcomitans↗