Notes: We analyze the mechanism by which positive ions and neutral species desorb from surfaces as a result of photon- or electron-beam induced electronic transitions. The system fluorine on aluminum is used as a prototype. We first present results of ab initio density-functional calculations of the potential energy curves of several charge states of fluorine on aluminum. We find that fluorine adsorbs as F−(2s22p6) and is strongly bound in the ground state. Valence (i.e., 2s22p5) and core (e.g., 2s12p6)-ionized states are, however, repulsive. F+(2s22p4) ions form bound states on Al but their adsorption energies are much smaller and their equilibrium distance is further out from the surface than those of F− ions. The difference in the bonding of positive and negative ions is ascribed to differences in the corresponding screening mechanisms. Screening of negative ions proceeds only by an image mechanism, while screening of positive ions can proceed by both image and charge–transfer mechanisms in which charge from the metal occupies the large-radius 3s and 3p orbitals of F. The resulting partially neutralized positive-ion states have reduced image attraction and increased electron kinetic energy (Pauli) repulsion. Franck–Condon transitions from the ground state populate the repulsive part of F+ potential energy curve and lead to efficient F+ desorption. F++ states are strongly bound and do not desorb. The same conclusions are reached by a more general analysis of the desorption of electronegative atoms from any metallic substrate, based on the concepts of effective medium theory. Finally, we discuss the applicability of our conclusions regarding the desorption of neutral and ionic fluorine to desorption of molecular adsorbates and also desorption from nonmetallic substrates.

Notes: Abstract. The aim of the present study was to examine the Actinobacillus actinomycetemcomitans carrier rate in Chinese subjects, and to determine serotype distribution, presence of the leukotoxin gene lktA and the structure of the lktA-promoter region. Subgingival microbiological samples were obtained from 31 Chinese subjects with moderate to advanced adult periodontitis, 73 young factory workers, and 81 adult residents of a rural area. Bacterial isolates phenotypically identified as A. actinomycetemcomitans were found in 116 of the 185 subjects (detection frequency over-all: 63%). Presence of the leukotoxin gene lktA was demonstrated for all 115 isolates that could be subcultured. The PCR analysis of the lktA-promoter region showed that none of these strains had the deletion in the promoter region known to enhance expression of lktA. No significant difference in the frequency of A. actinomycetemcomitans could be observed between the subjects of the 3 study groups. Analysis by logistic multiple regression indicated a homogeneous distribution of A. actinomycetemcomitans in the 3 cohorts and a lack of significant influence of subject gender or age. Serotype a was found in 21 subjects, serotype b was found in 9, serotype c in 67 and serotype e in 11 individuals. Serotype d was not detected in any subject. Nontypeable isolates, lacking serotype a, b, c, d, or e antigens, were found in 9 individuals. A high prevalence irrespective of gender, age, and cohort suggests that A. actinomycetemcomitans is a common constituent of the normal flora in the Chinese subjects of this study and suggests differences in the microbiological com- position of subgingival plaque may exist for this population group as compared to north American and European populations.

Notes: Abstract. The aims of the present study were to assess radiographically the effects of scaling/root planing combined with antibiotic therapy using tetracycline fibers (TCF): (II) on alveolar bone density and linear discriptors and (II) on supracrestal soft tissue density, 19 subjects with generalized adult periodontitis (with at least 20 teeth present, at least 4 teeth with pockets 〉4 mm and bleeding upon controlled force probing) and high cultural counts of Porphyromonas gingivalis were recruited from a pool of 57 patients. The full mouth treatment group (FT) consisted of 10 patients, who underwent a full mouth supra-gingival scaling and prophylaxis treatment and were instructed to rinse 2× daily with a 0.1% chlorhexidine solution. 1 week later, tetracycline-hydrochloride-containing fibers (Actisite® periodontal fiber) were applied around all teeth. After 7–12 days, the fibers were removed and all teeth were scaled and root planed under local anaesthesia. The chlorhexidine rinsing continued for another 2 months. In 9 subjects (local treatment group LT), 2 teeth with periodontal lesions with pocket probing pepth (PPD) ≥5 mm were treated by placement of tetracycline fibers, which remained in place for 7 to 12 days. Upon removal of the fibers, scaling and root planing was performed on these 2 teeth, while the rest of the dentition renamed untreated, and no chlorhexidine rinse was applied, 2 of the untreated teeth revealing similar periodontal lesions were chosen to represent sites affected by untreated periodontitis (NT). In this group, a limited local treatment was performed (2 teeth) with the inherent potential for recolonization from the untreated pocket sites. Standardized periapical radiographs were obtained from the 4 monitored sites within each patient at baseline (before treatment) and 2 and 6 months thereafter. One radiograph was exposed in a standard way for bone assessment. The second radiograph was underexposed, at about a 1/5 of the original exposure time to allow the evaluation of soft tissue. Mean changes in the near parameters and changes in density (CADIA) observed at multiple sites within each patient and treatment group were used as the best estimate of treatment outcome. Over the observation period of 6 months, a significant difference in bone height changes was found between the untreated sites (median loss –0.29 mm) and the sites from full-mouth treated patients (median gain 0.24 mm p=0.008). When comparing the baseline to the 6 months radiographs, a loss in bone density was observed for the untreated group (median=–2.13 CADIA), Both treatment groups revealed a gain in density (median= 1.58 and 2.43 CADIA for the locally and the full–mouth treated groups, respectively). Differences in density were significant, both between the nontreated and locally treated sites (p= 0.026) and between the nontreated sites and the sites from the full mouth treated patients (p=0.002). The analysis of the soft tissues showed a similar pattern of changes in density to those seen in the bone defect. At 2 months, there was a tendency for loss in density for the nontreated group (median=–0.17 CADIA) that continued over the 6 month period (median =–0.31 CADIA), A significant increase in density was observed for the full–mouth treated sites (median = 1.57 and 0.64 CADIA for the 2 and 6 months radiographs, respectively), A significant increase was also observed for the locally treated group when compared to the untreated sites (median=0.13 and 0.10 CADIA for the 2 and 6 months radiographs, respectively). Comparing untreated sites with full–mouth treated sites, a significant difference was observed for CADIA measurements (p〈0.001). No significant difference was observed comparing locally treated and untreated sites (p=0.24). It was concluded that scaling and root planing combined with TCF therapy can result in increased bone density and alveolar bone height. Full-mouth treatment seemed to result in more pronounced gains compared to local treatment. Untreated sites continued to lose alveolar bone height and density, CADIA of supracrestal soft tissue ROI paralleled the remodelling observed in bone ROI, This is the first controlled study revealing that CADIA of soft tissue ROI in series of underexposed standardized radiographs may render additional valuable information on remodelling of periodontal tissues after therapy.

Notes: abstract This survey attempted to determine the status of oral cleanliness and gingival health in 150 dental students and 101 faculty members in a dental school. Without advance notice, plaque deposits were scored, using the Plaque Index System, and gingival health was determined using the criteria of the Gingival Index System. The 1st-year students had the poorest hygiene and gingival health. An improvement (P 〈 0.01) was noted in the 2nd-year students who were still not in clinical training but had completed a course in preventive dentistry including oral hygiene techniques. Further improvement (p 〈 0.05) was found in students participating in the clinical courses (3rd and 4th years). However, some deterioration of both hygiene and gingival status occurred in the senior 5th year. Among the faculty, the best oral hygiene and gingival state were found in members of departments in which clinical work centered around patient motivation toward prevention and tooth conservation. The scores for plaque and gingivitis were worse in the departments of oral surgery, dental materials, orthodontics and the basic science departments. Almost all departments and every class showed a few individuals with very poor oral hygiene. It is suggested that regular patient contact influences the personal attitude toward oral hygiene, and that professional activity and emphasis on different aspects of the curriculum may be reflected in the attitude of health professionals toward oral health.

Notes: This study evaluated the influence of the image processing step of digital subtraction images on inter- and intraexaminer agreement in the interpretation of alveolar bone changes. 52 pairs of standardized radiographs from various clinical trails were included. Six dentists were invited to interpret the images projected as slides in random order. Display one demonstrated the slide of the digitized baseline radiograph and the follow-up image. Display two showed the regular digital subtraction image. Display three represented a grey level contrast enhanced version and displays four and five were pseudo/color enhanced subtraction images. Applying κ-statistics and multiple regression analysis it was demonstrated that better agreements were obtained when the two color coded displays of subtraction images were shown to the interpreters. The image interpretation was performed in two series. For the first evaluation the interpreters were not informed about the therapy provided nor the time elapsed between taking the pairs of standardized radiographs. In the second series this information was provided. It could be demonstrated that the agreement in the diagnosis of bone change was less influenzed by the knowledge about the clinical information if the two color-converted versions of subtracted images were evaluated. Thus, it was concluded that image processing of subtraction images using color enhancement might improve agreement in the diagnostic task. The color coded images were less influenced by the bias in the interpretation of an expected change. The decision making process might be more objective when using color enhanced subtraction images.

Notes: In this study, longitudinal changes in the composition of the subgingival microbiota of children between the ages of 11 and 14 and their association with changes of clinical parameters describing gingival health were investigated. During 4 years, subgingival microbial samples were taken in 22 boys and 20 girls 10 times. At the same time the gingival bleeding tendency was recorded by the Papillary Bleeding Index (FBI). A total of 840 samples was evaluated using darkfield microscopy and anaerobic culturing on non-selective and selective media. Children, who developed a marked and sustained increase in mean PBI scores (n = 21), had higher frequencies and mean proportions of spirochetes and Eikenella corrodens than children without pronounced puberty gingivitis (p 〈 = 0.05). The mean proportion of Actinomyces viscosus was also higher in these children (p 〈 = 0.05). Among the species discriminated, only Capnocytophaga sp. were found at a higher rate in samples taken immediately before a rise of PBI (p 〈 = 0.05). The detection frequencies of black-pigmented Bacteroides (particularly B. intermedius) increased later, and were significantly elevated after the establishment of a high bleeding tendency (p 〈 = 0.05). These findings implicate Capnocytophaga sp. in the initiation of puberty gingivitis, whereas the increased presence of Bacteroides may reflect a change in the subgingival environment secondary to increased bleeding.

Notes: A 3-month clinical trial was conducted to compare the effects of two concentrations of a chlorhexidine mouthrinse on gingivitis and plaque accumulation. Six hundred (600) adults were divided into three treatment groups matched for age, sex, and initial gingivitis severity. Following a thorough examination and prophylaxis at baseline, subjects were given a mouthrinse containing either 0.12% or 0.20% chlorhexidine gluconate or a placebo mouthrinse. Subjects were evaluated after 6 weeks and 3 months of mouthrinse use. After 3 months, both chlorhexidine groups showed significantly less gingivitis and plaque than the placebo group. The group using the 0.12% chlorhexidine gluconate mouthrinse demonstrated 27–27 % less gingivitis occurrence and 28–28% less gingivitis severity than the placebo group. The 0.12% chlorhexidine gluconate group also had 48–48% less gingival bleeding and 36% less plaque than the placebo group. There were no significant advantages for the 0.20% mouthrinse over the 0.12% mouthrinse. It is therefore concluded that a 0.12% chlorhexidine gluconate mouthrinse offers the same clinical benefits as a 0.20% chlorhexidine gluconate mouthrinse.

Notes: After prophylaxis, 5 dental hygienists performed optimal oral hygiene under supervision for 6 months. At months 0, 1, 4 and 6, Plaque Index, Gingival Exudate Flow Rate and Gingival Index were assessed, and a buccal biopsy of their gingiva taken. Point counting procedures were performed at 2 different levels of magnification to estimate the volume densities of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The percentages of fibroblasts, polymorphonuclear neutrophilic granulocytes, lymphocytes, plasma cells and macrophages were estimated by counting the number of profiles of these cells in the connective tissue area close to the apical end of the junctional epithelium. All the changes inside the tissue occurred slowly. During the 6-month period there was a continuous increase of the volume density of the epithelium in the gingiva. An increase in the percentage of fibroblasts was observed between months 1 and 4 together with a decrease in the percentage of lymphocytes and in the volume density of the infiltrated connective tissue. Between months 4 and 6 an increase of the volume density of the collagen was found together with a further increase in the percentage of fibroblasts and a further decrease in the percentage of lymphocytes. After 6 months of perfect oral hygiene no more plasma cells were visible. This study has shown that, even in presence of clinically healthy gingiva, subclinical changes may take place. It appears realistic to accept the presence of a very mild gingivitis localized in an area adjacent to the attachment as compatible with gingival health.

Notes: It has been suggested that the vascular alterations found in inflamed gingiva may be of significance in the enhanced extension of the pathological process into the periodontium. The purpose of this investigation was to measured the changes in blood vascular volume occurring in gingiva with the onset of gingivitis and its resolution. Twenty-six individuals participated in this study. Gingival biopsies were taken following a 21-day experimental gingivitis, following resolution of a 21-d experimental gingivitis and during a 6-month experimental gingivitis and a 6-month period of optimal oral hygiene. A total of 126 biopsies was obtained, from which 378 sections were cut at 2 μm for stereological analysis. At low magnification, reference volumes were estimated using point counting procedures and expressed as mm3 of gingiva per mm length of vestibular gingiva, in a vestibulo-lingual plane. At higher magnification the ratio between the volume of vessels and connective tissue was calculated. The final results were expressed as mm3 of vessels per mm length of vestibular gingiva, in a vestibulo-lingual plane. The mean vessel volume expressed per unit length of vestibular gingiva ranged from 0.010 to 0.024 mm3/mm. No statistically significant differences in vascular volumes were found between inflamed and non-inflamed gingiva. It was concluded that the changes in vascular architecture during early gingivitis described in the literature had either taken place in the subjects prior to the time of experimentation or that any vascular changes (cytologic or functional) which had taken place may be compensatory for the changes in architecture described in the literature.