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Notes: Conventionally, the simulation of thin films has been carried out using an HCP structure to represent its physical structure. Such an idealized structure has been shown to overestimate the effect of interparticle coupling by using an homogeneous exchange coupling scheme. A more realistic approach to represent physical structure has been undertaken by generating a system of grains which lie on a radially isotropic structure and have a nonuniform volume distribution. Interaction effects can be shown by computing δI curves formed through the comparison of the remanence curves using the Wohlfarth relation. To generate an isothermal remanence curve (IRM), a realistic ac erased state is necessary which has been carried out by using a simulated annealing technique. A comparison has been made to determine the effect of physical structure on the bulk properties by computing hysteresis loops, remanence curves, and δI curves. To reduce statistical error these have been averaged over four different sets of easy axes. The loops indicate that an irregular physical structure leads to an increase in the coercivity and decrease in the squareness. The dc-demagnetization curves show an increase in remanent coercivity; this can be attributed to the random physical structure decreasing the size of magnetically correlated regions within the microstructure. The effect of the physical microstructure on the δI curves will be discussed in full in the paper. © 1996 American Institute of Physics.

Notes: Abstract The effect of improved metabolic control on the clinical periodontal condition and the subgingival microflora of diseased and healthy periodontal pockets in 6 ambulatory insulin-dependent diabetes mellitus (IDDM) patients was prospectively studied. Duplicate measurements with a time-interval of 3 days were made every 4 moths for assessment of the metabolic status, the clinical periodontal condition and the subgingival microflora. During the study, patients maintained personal oral hygiene measures as they usually did before the study. Neither supplementary dental prophylaxis nor oral hygiene measures were applied during the investigation. Long-term metabolic control (HbA1c) improved significantly with intensive conventional insulin treatment. Gingival redness decreased significantly whereas gingival swelling showed a not significant trend to decrease. It is suggested that microvascular changes associated with improved metabolic control in diabetes mellitus may mediate the observed change in gingival redness. No effect could be demonstrated for probing pocket depth, probing attachment level, bleeding on probing and the plaque index. Statistical analysis of the effect of improved metabolic control on the subgingival microflora revealed that only the % of streptococci increased significantly in diseased periodontal pockets. In general, no significant changes were found in either healthy or diseased pockets with regard to the bacterial flora associated with periodontal disease. The results of the present study indicate that improved metabolic control in IDDM patients may have no potential impetus for an improved clinical periodontal condition nor on the subgingival bacterial flora. It is concluded that the periodontal condition in IDDM patients may only ameliorate when local oral hygiene measures are applied.

Notes: Abstract The purpose of the present investigation was to study the effect of age on the rate of development of gingival inflammation in individuals not susceptible to periodontal destruction. 7 younger (mean age 37 years) and 7 older (mean age 58 years) individuals were selected on the basis of the presence of at least 18 teeth, no evidence of extraction due to periodontal destruction, no loss of attachment, shallow pockets, gross amounts of plaque and a history of no interdental cleaning. All individuals were subjected to a carefully controlled oral hygiene program and experimental gingivitis was induced in 1 quadrant of the mouth during a period of 33 days. The amount of plaque, redness and swelling of the gingivitis, and bleeding on probing were assessed before, during and after the experiment. Al day 33, supra-gingival plaque samples were taken for bacteriological examination and gingival biopsies were taken for histopathological and immunohistochemical investigation. Results showed no differences between the 2 age groups with regard to the amount of plaque accumulation and the rate of development of gingival inflammation. Furthermore phase-contrast microscopy of plaque samples showed no differences between the 2 age groups. Neither his to-logical nor immunohistochemical investigation showed any differences between the 2 age groups. All biopsies diffusely showed presence of IgG, whereas in most biopsies, IgA plasma cells and in one biopsy IgM plasma cells were found. Neither IgD, IgE nor complement deposits were found. It was concluded that age is of minor importance in the development of experimentally-induced gingivitis in individuals not susceptible to periodontal destruction.

Notes: Objectives: Current literature is ambivalent on the use of barrier membranes for regeneration of intraosseous defects. One of the reasons for unpredictable results may be related to infection before, during and after the surgical procedure. Therefore, the purpose of the present controlled study was to evaluate both the use of membranes (MEM) and antibiotics (AB), separately and in combination.Methods: In all, 25 patients with two intraosseous periodontal defects each were randomized in two groups: AB+ group receiving systemic antibiotics (n = 13) and AB– group without antibiotics (n = 12). After raising flaps and after debridement, both defects in each patient were covered by a bioresorbable membrane (MEM+). However, just before suturing the flaps in a coronal position, the membrane over one of the two defects was removed at random (MEM–). This protocol resulted in four groups of defects: (i) MEM– AB–; (ii) MEM+ AB–; (iii) MEM– AB+ ; (iv) MEM+ AB+. Patients were monitored clinically and microbiologically for 1 year. Data were analyzed in repeated measures ancova's and adjusted means for clinical variables were obtained from the final statistical model.Results:  Reduction in probing pocket depth (PPD) at 12 months postoperatively varied between 2.54 and 3.06 mm between the four treatment modalities, but overall no main effect of MEM or AB was found. Gains in probing attachment level (PAL) at 12 months postoperatively varied between 0.56 and 1.96 mm for the 4 treatments. In the overall analysis for PAL, no main effect of MEM or AB was found. Gains in probing bone level (PBL) 12 months postoperatively ranged from 1.39 to 2.09 mm between the treatment groups. Again, overall, no main effects of MEM or AB were found for PBL. Explorative statistical analyses indicated that smoking and not MEM or AB is a determining factor for gain in PBL (P = 0.0009). Nonsmokers were estimated to gain 2.04 mm PBL compared to 0.52 mm in smokers. The prevalence of several periodontal pathogens, at the day of surgery or postoperatively, and specific defect characteristics, were not determining factors for gain in PAL and PBL.Conclusions:  Neither the application of barrier membranes nor the use of systemic antibiotics showed an additional effect over control on both soft and hard tissue measurements in the treatment of intraosseous defects. In contrast, smoking was a determining factor severely limiting gain in PBL in surgical procedures aimed at regeneration of intraosseous defects.

Notes: Abstract In a recent publication, it was hypothesized that the ratio between bleeding and plaque scores may act as a prognostic indicator for periodontal breakdown. Furthermore, it was found that the rate of development of gingival inflammation in terms of bleeding on probing during experimental gingivitis is more rapid in patients susceptible to periodontal breakdown than in subjects insusceptible to periodontal breakdown. The purpose of the present investigation was to compare the gingival reaction to dental plaque in an experimental gingivitis study in individuals without periodontal breakdown, having either a low or a high bleeding/plaque ratio. A group of 8 volunteers (18–23 years) with a low bleeding/plaque ratio and 7 volunteers (19–22 years) with a high bleeding/ plaque ratio were selected. In both groups, an experimental gingivitis study of 23 days duration was carried out. Results showed that individuals with a high bleeding/plaque ratio developed significantly more clinical inflammation in terms of bleeding and swelling of the gingiva than individuals with a low bleeding/plaque ratio. After 23 days of plaque accumulation, gingival biopsies as well as supragingival plaque samples were taken from both groups. Phase-contrast microscopy of the plaque samples showed no significant differences between the 2 groups. Low %s of spirochetes and motile rods were found. Stereologic point-counting procedures snowed equal amounts of infiltrated connective tissue in both groups. However, significant differences in composition of the infiltrate appeared to be present. The high ratio group showed more IgA producing plasma cells and complement activation than the low ratio group. The results of the present study suggest that the bleeding/plaque ratio of an individual may be regarded as a prognostic indicator for the degree of experimentally induced gingival inflammation in terms of bleeding and swelling of the gingiva as well as complement activation and IgA-plasma cell activity.

Notes: Abstract The purpose of the present study was to investigate the effect of mechanical oral hygiene procedures on bleeding on probing in relation to age and periodontal status. The study was carried out on 49 indivuals divided into 7 experimental groups according to age and having been either treated for destructive periodontal disease or having an intact healthy periodontium. In order to eliminate any pre-existant gingival inflammation, all subjects received a carefully controlled oral hygiene program. At the start of the experiment, all subjects were instructed to abstain from oral hygiene procedures for 24 h. Thereafter, clinical baseline measurements were carried out, including bleeding on probing (BOP) using a standardized probing pressure. Next, all subjects cleaned their teeth according to their normal oral home care protocol using a multitufted toothbrush, toothpicks and interdental brushes. BOP scores were again assessed 30 min after completed tooth cleaning procedures. The results revealed a significant increase in BOP after the mechanical oral hygiene procedures in every individual in all experimental groups (p 〈0.05). Further analysis showed that the increase in BOP was independent of the periodontal status of the subjects. However the BOP scores after mechanical oral hygiene procedures were higher in the young age groups. It was concluded that the diagnostic predictability of BOP in the treatment of periodontal diseases might be affected by temporarily elevated BOP scores shortly after mechanical oral hygiene procedures.

Notes: Abstract The aim of the present study was to investigate the rate of development of experimentally-induced gingival inflammation in relation to the susceptibility to periodontal disease. By selection according to age, a younger (25–39 years) and an older (45–54 years) age group, with a comparable reduced but healthy periodontium, was selected. This equal amount of periodontal breakdown may suggest that the younger age group represented individuals with a relatively higher degree of susceptibility to periodontal disease. At the start of the experiment, each patient was instructed to abstain from oral hygiene procedures in 1 quadrant of the mouth for a period of 18 days. Results showed that all subjects developed signs of gingival inflammation. Regarding the development of redness and swelling, no differences could be assessed between the 2 age groups. However, analysis of the bleeding scores revealed that bleeding on probing developed more rapidly in the younger age group. It was concluded that those patients who have suffered from a more rapid form of periodontal disease also develop inflammation, in terms of bleeding on probing, more rapidly.

Notes: Background: When the subgingival presence of periodontal pathogens is studied in groups of patients or populations, mostly a number of the deepest sites is sampled. The mean clinical parameters of these deep sites are also frequently used as a the descriptor of the clinical situation of these subjects. It can be questioned, whether these 4 deep sites are capable of predicting a full-mouth situation.Aim: The purpose of the present retrospective study was to investigate to what extent the experienced progression of periodontitis as measured in the deepest approximal pocket in each quadrant reflects the disease progression at the approximal sites on a full-mouth level.Methods: A data set of a 7-year longitudinal study of 158 young subjects (69 male, 89 female, 15–25 years of age at baseline) was used. Clinical assessments included plaque index (PI), pocket depth (PD) and attachment loss (AL) at baseline (1987) and follow-up (1994). Measurements were made at the approximal surfaces of all teeth. The deepest pocket in each quadrant was determined at follow-up. Changes of the clinical parameters between baseline and follow-up were calculated both as full-mouth mean scores as well as for these 4 deepest sites. A regression analysis was used to evaluate the relationship between full-mouth score and the 4 test sites.Results: For disease progression between baseline and follow-up, significant correlation coefficients were observed between the 4-site and full-mouth mean changes (PD: 0.80, AL: 0.70, PI: 0.77). Regression coefficients were 0.51 for PD, 0.35 for AL and 0.55 for PI. The precision of the estimate for the full-mouth mean, as predicted by the 4-site mean, is determined by the residual standard deviation. This was for PD 0.31 mm, for AL 0.31 mm and for PI 0.29. Compared to the between-patient standard deviation of the full-mouth means, the residual standard deviations were high.Conclusion: In the present population, a reasonable to good correlation between full-mouth and 4-sites data was observed. However, the high residual standard deviation in the regression analysis illustrates the inaccuracy for the 4-sites data when used as a descriptive for changes in the periodontal condition on a full-mouth level. Data evaluating progression of periodontitis based on a limited number of diseased sites should be interpreted cautiously.

Notes: Abstract. In the present investigation wound healing was studied clinically in 8 younger (mean age 33.5 years) and 8 older patients (mean age 48 years), who were surgically treated for the same amount of severe periodontitis. This implies that the patients in the younger age group represented individuals with a higher degree of susceptibility to periodontal disease than the patients in the older age group. After surgery all patients were subjected to a carefully controlled oral hygiene program. Patients were recalled weekly until 8 weeks post surgery and again after 15 weeks for a final examination. At every recall session oral hygiene measurements were carried out and the bleeding tendency of the pockets was determined after probing with a standardized pressure. Bleeding on the basis of mechanical trauma after probing was considered to be a clinical parameter for wound healing in a plaque free environment.Results indicate that the oral hygiene program resulted in equally low plaque scores in both age groups. However, in a period from 5–15 weeks after surgery younger patients showed significantly more bleeding pockets than older patients. Furthermore it was found in both groups that the more loss of attachment there was, the slower the rate of wound healing.It was concluded that the time span for wound healing is longer in patients who are more susceptible to periodontal disease, than in those who are less susceptible.

Notes: The supercurrent in a Nb–In0.53Ga0.47As/In0.77Ga0.23As/InP weak link structure is controlled by means of a current injected into the two-dimensional electron gas. For small injection currents the critical current to control current ratio is as large as 20. The measured features can be qualitively explained in terms of a modification of the Andreev level occupation by the injected carriers. © 1998 American Institute of Physics.