Library

Notes: Bulk melt textured YBa2Cu3O7−δ samples with single grains of about 24 mm diameter were obtained by use of SmBa2Cu3O7−x seed crystals. The maximum trapped field B0 in the gap between two samples was investigated as function of temperature. B0 increased from 1 T at 77 K to 8.5 T at 51.5 K, which is the highest trapped field achieved in nonirradiated samples. At low temperatures, cracking of the samples was observed under magnetic pressure. In this temperature range, the trapped field is limited by the mechanical strength of the samples, for which a value of 25 MPa was estimated. © 1997 American Institute of Physics.

Notes: High-quality binary (Nd0.33Sm0.67)Ba2Cu3O7−δ monodomain superconductors were fabricated by the combination of a compositional-controlled melt-processing technique in air and postannealing in Ar. Critical current densities over the whole field range were observed strongly dependent on Ar postannealing while holding superconducting transition temperatures as high as 96 K. The suppressed chemical variation between the rare-earth element (RE: Nd, Sm) and Ba associated with disperse RE2BaCuOy (RE211) precipitate due to the decomposition occurring in Ar postannealing was attributed to the modified flux pinning. This makes Ar postannealing promising to process superconductors with desired properties for various applications. © 1999 American Institute of Physics.

Notes: High trapped fields were found in zinc-doped, bulk melt-textured YBa2Cu3O7−x (YBCO) material showing a pronounced peak effect in the field dependence of the critical current density. Trapped fields up to 1.1 T were found at 77 K at the surface of a YBCO disk (diameter 26 mm, height 12 mm). Very high trapped fields up to 14.35 T were achieved at 22.5 K for a YBCO disk pair (diameter 26 mm, height 24 mm) by the addition of silver and using a bandage made of stainless steel. The pinning forces and trapped fields obtained in bulk YBCO material are compared with results reported for melt-processed NdBa2Cu3O7−x and SmBa2Cu3O7−x.© 2000 American Institute of Physics.

Notes: Aim: The purpose of this investigation was to examine the long-term relationship between dental restorations and periodontal health.Material and Methods: The data derived from a 26-year longitudinal study of a group of Scandinavian middle-class males characterized by good to moderate oral hygiene and regular dental check-ups. At each of 7 examinations between 1969 and 1995, the mesial and buccal surfaces were scored for dental, restorative and periodontal parameters. The mesial sites of premolars and molars of 160 participants were observed during 26 years (1969–1995). A control group with 615 sound surfaces or filling margins located more than 1 mm from the gingival margin in all 7 surveys was compared with a test cohort with 98 surfaces which were sound or had filling margins located more than 1 mm from the gingival margin at baseline (1969) and had a subgingival filling margin 2 years after (1971).Results and conclusions: The study confirmed the long held concept that restorations placed below the gingival margin are detrimental to gingival and periodontal health. In addition, this study suggests that the increased loss of attachment found in teeth with subgingival restorations started slowly and could be detected clinically 1 to 3 years after the fabrication and placement of the restorations. A subsequent “burn-out” effect was suggested.

Notes: Aim: The purpose of this study was to assess the initiation and progression of periodontal disease during adult life.Materials and Methods: In a 26-year longitudinal investigation of the initiation and progression of chronic periodontitis that started in 1969 and included 565 men of Norwegian middle class, 223 who had participated in some, but not all, intermediate examinations presented at the last survey in 1995. Fifty-four individuals were available for examination in all seven surveys.Results: Covering the age range from 16 to 60 years, the study showed that at 16 years of age, 5% of the participants had initial loss of periodontal attachment (ILA〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03036979:JCPE399:ges" location="ges.gif"/〉2 mm) at one or more sites. Both the subject incidence and the site incidence increased with time, and by 32 years of age, all individuals had one or more sites with loss of attachment. As age progressed, new lesions affected sites, so that as these men approached 60 years of age approximately 50% of all available sites had ILA.An assessment of the intraoral distribution of the first periodontal lesion showed that, regardless of age, molars and bicuspids were most often affected. At and before the age of 40 years, the majority of ILA was found in buccal surfaces in the form of gingival recession. By 50 years, however, a greater proportion of sites presented with attachment loss attributed to pocket formation or a combination of pocket formation and gingival recession. As individuals neared 60 years of age, approximately half of the interproximal areas in posterior teeth had these lesions.Conclusion: This investigation has shown that, in a well-maintained population who practises oral home care and has regular check-ups, the incidence of incipient periodontal destruction increases with age, the highest rate occurs between 50 and 60 years, and gingival recession is the predominant lesion before 40 years, while perio-dontal pocketing is the principal mode of destruction between 50 and 60 years of age.

Notes: Objectives:  The purpose of this study was to determine the influence of long-standing gingival inflammation on periodontal attachment loss. On the basis of repeated examinations, the present report describes the influence of gingival inflammation on the initiation of periodontitis from 16 to 59 years of age.Material and Methods:  The data originated from a 26-year longitudinal study of Norwegian males, who practiced daily oral home care and received state-of-the-art dental care. The initial examination included 565 individuals. Subsequent examinations took place in 1971, 1973, 1975, 1981, 1988 and 1995. Thus, the study covers the age range of 16–59 years. All tooth sites were divided into four categories according to their history of gingival inflammation over the entire observation period: sites always scoring GI=0, GI=1 and GI=2 sites (GI=gingival index). Sites disclosing various GI scores at different observation periods were not considered.Results:  The mean cumulative attachment loss for non-inflamed (GI=0) sites in individuals approaching 60 years of age was 1.94 mm. Sites always scoring GI=1 yielded 2.42 mm, and sites that always scored GI=2 exhibited 3.31 mm of periodontal attachment loss. At interproximal sites of all three groups where gingival trauma was assumed to be minimal or non-existent, only very few sites expressed attachment loss due to gingival recession (2–4%). At interproximal sites always scoring GI=0, 20% loss of attachment was in the form of pocket formation by 59 years of age. The GI=1 and the GI=2 cohorts exhibited attachment loss with pocket formation in 28% and 54%, respectively.Conclusion:  This study has shown that, as men approach 60 years of age, gingival sites that throughout the 26 years of observation bled on probing had approximately 70% more attachment loss than sites that were consistently non-inflamed (GI=0). Before 40 years of age, there was a slight increase in periodontal attachment loss due to pocket formation, but after this, the frequency increased significantly. Loss of attachment due to gingival recession was very small in all three groups.The fact that sites with non-inflamed gingiva also exhibited some loss of attachment and pocket formation may be explained by fluctuation in the variations of tissue status during long observation intervals combined with the presence of subclinical inflammation.

Notes: Aim: The purpose of this study was to assess the long-term influence of gingival inflammation on tooth loss.Material and Methods: The data originated from a 26-year longitudinal study of Norwegian males, who practiced adequate daily oral home care and received “state-of-the-art” dental care. The initial examination in 1969 included 565 individuals aged between 16 and 34 years. Subsequent examinations took place in 1971, 1973, 1975, 1981, 1988 and 1995. Thus, the study covers the age range of 16–59 years. The teeth were divided into three tooth groups (I–III) reflecting the history of inflammation of the surrounding gingiva (gingival index (GI) scores) over 26 years: (I) teeth with surrounding gingival units scoring a minimum of one site with GI=0 and a maximum of three sites with GI=1, (II) teeth with surrounding gingival units scoring a minimum of one site with GI=1 and a maximum of three sites with GI=2 over the observation periods and (III) teeth with surrounding gingival units always scoring a minimum of GI=2 (bleeding on probing) at all sites over the observation period.Results: At baseline (1969), out of possible 15,820 teeth (565 × 28), 15,383 teeth were present. Four hundred and thirty-seven teeth had already been missing for unknown reasons. By 1995, 13,159 teeth were reexamined, i.e. over the 26-year observation period only 126 (0.95%) teeth were lost. Only 16 (0.28%) of 5793 teeth belonging to GI-Severity Group I were lost. In the GI-Severity Group II, however, 78 (2.28%) out of 3348 teeth were lost, and 13 (11.21%) of 103 teeth with GI-Severity Group III were lost. Teeth with GI-Severity Group III yielded an odds ratio for tooth loss that was 46 times higher than that of teeth with GI-Severity Group I, and five times higher than that of teeth with GI-Severity Group II over 26 years. Furthermore, teeth with the GI-Severity Group II had a nine times higher risk for tooth loss than teeth with the GI-Severity Group I.The GI-Severity Group I retained 99.5% of the teeth after a tooth age of 51 years. The GI-Severity Group II retained 93.8% of the teeth after a tooth age of 50 years. However, in the GI-Severity Group III, 63.4% of the teeth were retained for a tooth age of 47 years.Conclusions: Teeth surrounded with inflammation-free gingival tissues were maintained for a tooth age of 51 years, while teeth consistently surrounded with inflamed gingivae yielded a 46-times higher risk to be lost. Only two-thirds of such teeth were maintained throughout the 26-year observation period. This documents the role of gingival inflammation as a risk factor for future tooth loss.

Notes: Aim: The purpose of this study was to assess the rate of attachment loss during various stages of adult life in a well-maintained middle-class population.Material and Methods: The data originated from a 26-year longitudinal study of Norwegian males who had received regular and adequate dental care and practised daily oral home care. The initial examination in 1969 included 565 individuals aged between 16 and 34 years. Subsequent examinations took place in 1971, 1973, 1975, 1981, 1988 and 1995. Thus, the study covers the age range of 16–59 years. The rate of the annual attachment loss was calculated as the difference between the individual mean attachment loss between two examinations divided by the years between examinations. The mean annualized relative risk of attachment loss was calculated as the frequency distribution of sites with initial periodontal attachment loss (loss of attachment at the first time of occurrence 〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:03036979:JCPE401:ges" location="ges.gif"/〉2 mm) and healthy sites (loss of attachment always 〈2 mm). For comparison of significant changes in annual attachment loss rates between the age groups and mean annualized relative risks of attachment loss as they proceeded through adult life, the Wilcoxon Mann–Whitney U-test was used.Results: The mean overall individual attachment loss during 44 years (between 16 and 59 years) totaled 2.44 mm (range 0.14–2.44 mm), averaging an annual mean rate of 0.05 mm/year. The highest annual rate of attachment loss occurred before 35 years of age (0.08–0.1 mm/year), after which the mean annual rate decreased to about 0.04–0.06 mm/year for the next three decades of life leading to 60 years. The mean annualized relative risk of initial attachment loss increased significantly from adolescence (1.2%) to the maximum at 30–34 years of age (6.9%). After the age of 34 years, the risk of initial attachment loss decreased again, but after the age of 40 years, another continuous increase was observed.Conclusions: Over a 26-year period, 25% of the subjects went through adult life with healthy and stable periodontal conditions. The remaining 75% developed slight to moderately progressing periodontal disease with progression rates varying between 0.02 and 0.1mm/year with a cumulative mean of loss of attachment of 2.44mm as they approached 60 years of age. The annual mean rate and the mean annualized risk of initial attachment loss were highest between 16 and 34 years of age. Only 20% of the sites continued to lose further attachment during the remainder of the observation period, and less than 1% of the sites showed substantial loss of attachment (〉4mm).

Notes: Summary Animal experiments with groups of 25 female mice each were performed to assess the influence of proluton or nortestosterone acetate (the progesterone component of “Anovlar”) on their larynges with special attention to induced alterations. Such alterations had indeed been observed after administration of testosterone: fibers in the pars interna of the thyro-arytenoid muscle were broadened, the RNA synthesis increased, and glycogen was incorporated into the muscle fibers at an increased rate. According to the morphological results of the present study, neither prolution (progesterone) nor nortestosterone acetate causes comparable effects. That is to say, the thickness of the muscle fibers of pars interna as well as the histochemical reactions (RNA, glycogen) were not significantly different from those found in control groups. Furthermore, the surface epithelium of the vocal cord remained equally unchanged.