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Notes: The first measurements of the microwave surface resistance at 18 GHz of bulk Tl-Ba-Ca-Cu-O superconductors produced by the hot isostatic pressing (HIP) process are reported. The superconducting samples, prepared by solid-state reaction with subsequent sintering and consolidation to obtain ideal density, were measured by replacing the end wall of a TE011 circular mode gold-plated copper cavity with the sample and determining the cavity Q for the temperature range 4–300 K. Results indicated that HIP samples which underwent subsequent annealing exhibit, below the critical temperature, a surface resistance approaching an order of magnitude less than copper.

Notes: Abstract This study investigates bacterial invasion of the soft tissue walls of deep pockets from cases with adult (AP) and juvenile periodontitis (JP). Transmission electron microscopy was used to examine pocket soft tissue walls removed from extracted teeth from 5 patients with AP and 2 patients with JP. Bacteria were sparse throughout the epithelium and connective tissue, regardless of the level of tissue breakdown. However many inflammatory cells were seen, and these did appear to be located in regions of marked collagen loss. Accumulations of large numbers of bacteria were extremely rare and found only on the epithelial surface or in artefactual spaces within the deeper tissues. The findings indicate that the tissue destruction associated with periodontitis is not directly related to bacterial invasion. The sparse organisms within the pocket tissues probably result from passive entry rather than an invasive action. Under these circumstances, it would seem reasonable to suggest that bacterial metabolic products rather than the micro-organisms themselves penetrate the tissues in periodontitis.

Notes: Abstract The surfactants tetradecylamine, hexadecylamine and chlorhexidine have been compared with regard to their ability to inhibit microbial growth. Antibacterial activity was assessed by tube dilution methods. Tetradecylamine and chlorhexidine were similar in antibacterial activity, being effective at low concentrations against most organisms tested. Hexadecylamine also inhibited growth but at higher concentrations. Viable counts of salivary organisms were monitored in volunteers over 48 h after one rinse with the agents. The initial reduction in numbers of total viable salivary bacteria and streptococci by tetradecylamine and of streptococci by hexadecylamine had disappeared 3 h after a single mouth rinse, but the reduction in numbers of all salivary bacteria by chlorhexidine was more prolonged.

Notes: Abstract This study compared a simplified oral hygiene regime (scaling, root planing and Bass brushing) with this same regime plus 0.02% chlorhexidine (CH), 0.05% metronidazole (MD) and inactive control (PL) solutions delivered supra-gingivally by a pulsating water jet irrigator.22 patients were distributed randomly into 3 groups, 0.02% chlorhexidine (CH), 0.05% metronidazole (MD), and inactive control (PL). Approximal surfaces with associated pockets ≥ 4 mm were monitored at day 0, for plaque index (PII), gingival index (GI), sulcus bleeding index (SBI), baseline measurement for gingival shrinkage and probeable pocket depth. All monitored surfaces were then immediately scaled and root planed. All patients received identical oral hygiene instruction (Bass brushing), with a sodium fluoride toothpaste and a multituft toothbrush, and were shown how to use the oral irrigator. Proficiency in use of the oral irrigator was checked again at day 7. No interdental cleaning was taught. The active treatment period was 28 days. Patients were seen at days 7, 28, 56 and 84, and all parameters were recorded at each visit, but no further oral hygiene instruction was given.Within procedure comparisons of the findings at days 28 (end of active treatment) 56 and 84 with those at day 0, showed statistically highly significant improvements in all parameters for all groups. Regarding between procedure comparisons, CH was better in reducing PlI at all times except at day 84, and on several occasions in reducing GI and SBI. Irrigated groups were always better than non-irrigated groups. Although the differences were statistically highly significant, clinically the differences between groups were relatively small, except for CH effect on PlI. It was concluded that an oral hygiene regime of scaling, root planing and Bass brushing is statistically less effective in reducing PLI, GI and SBI than the same regime with once daily supragingival irrigation with a pulsating jet oral irrigator, especially using CH (0.02%).

Notes: Abstract 23 patients with pockets ≥ 4 mm and evidence of bone loss on radiographs received thorough scaling and root planing followed by instruction in Bass brushing. They refrained from routine interdental cleaning for the first 28 days. A pulsating jet irrigator was used once daily supragingivally with 0.02% chlorhexidine (CH) 0.05% metronidazole (MD) or 0.01% quinine sulphate inactive control (PL), on a randomized double blind basis. Molar sites were not irrigated and served as control sites; they were only mechanically cleaned.For each patient, subgingival plaque samples were obtained from 2 test and 1 control sites at baseline (day 0), and on days 7, 28, 56 and 84. Plaque samples were monitored by darkfield microscopy on the basis of morphological characteristics of 4 types of bacteria: cocci, motile cells, spirochaetes and “others” (non-motile rods, filaments and fusiforms).The simplified oral hygiene regime of scaling, root planing and Bass toothbrushing combined with interdental supragingival pulsating jet irrigation with CH, MD or PL appeared superior to a system of simplified oral hygiene alone, particularly during the first 4 weeks. However, at most time-points, the benefits were notstatistically significant except for metronidazole. By day 84, the end of the experimental period, all groups approximated baseline levels.The results indicate that supragingival pulsated jet irrigation has limited effects on the composition of subging plaque. More marked changes occur when the irrigation fluid contains a chemical agent such as metronidazole known to be effective against important subgingival organisms, but probably not to such an extent as to change the composition of the flora from one associated with diseased sites to one associated with healthy sites.

Notes: Abstract. This study considers false results which may arise due to problems in the preparation or examination of specimens for darkground microscopy of subgingival plaque. Subgingival plaque samples obtained with a sterile curette were placed in 0.1–0.3 ml sterile full or 1/4 strength Ringer's solution: 0.85% saline, 1% gelatin in 0.85% saline, formal saline or pyrogen-free water for injection. Test slides were prepared from the original dispersion, and control slides from the corresponding sterile solution. Optimal dispersion solution, syringe dispersion frequency and the effect on motility of delay in processing samples were tested. Slides were also prepared from dispersions of 11 representative subgingival “periodontopathic” organisms. Problems in sampling included variability in counts between sites with comparable pocket depths, contamination of the sample and reduction of the sample volume after scaling. Problems in dispersion included contamination, uneven distribution of the different morphotypes and destruction of delicate organisms. Problems in slide preparation included slide contamination, limitation in the number of samples that can be assessed by one examiner at a given time without loss of activity of motile cells, and preparation of a cell monolayer. Problems in identification and counting included confusion of Brownian movements with motility, coccoid particles with cocci, spirochetes with campylobacter, flagella with flagella-like structures, size of cocci, counting of fragmented spirochetes and non-motile flagellated organisms and motile cells, and also bias in counting. Problems in morpbotype grouping included the observation that many (10 of the 11 representative) periodontitis-related organisms were in the non-motile groups and not all cells of the motile species (Campylobacter, Capnocytophaga) showed motility.The results indicate that each stage of subgingival plaque darkground microscopy, sampling, dispersion, slide preparation, counting, morphotype grouping and interpretation may lead to false results if not representative or reproducible. Procedures are suggested for the minimisation of problems in the preparation and examination of subgingival plaque specimens for darkground microscopy.

Notes: Abstract The aim of this study was to investigate the effects of a simplified system of oral hygiene, comprising Bass brushing, scaling, root planing and subgingival irrigation using a pulsated monojet oral irrigator, in patients with chronic periodontitis.After initial assessment, patients received scaling, root planing and instruction in Bass brushing and in use of a pulsated jet oral irrigator (Water Pik + Imax attachment) to irrigate subgingivally. 11 patients with 262 approximal periodontal pockets used 0.02% chlorhexidine (CH), or a placebo as the irrigating solution once daily for 28 days. Plaque index (P1I), sulcus bleeding index (SBI), and probing pocket depth (PPD) were assessed on days 0, 28, 56 and 84. Within procedure comparisons for all groups showed that the regime was highly effective in reducing P1I, SBI and PPD, improvements being maintained at least until day 84. Between procedure comparisons showed that benefits were improved only marginally by the use of 0.02% CH as the irrigation fluid. The patients found the procedure pleasant and neither injuries nor staining were noted during the study.It was concluded that this simplified oral hygiene system was effective in reducing periodontal inflammation and pocket depth, although no significant added benefit with 0.02% CH was apparent. The technique may be useful in patients who cannot achieve high levels of routine mechanical oral hygiene, particularly interdentally. The effects of using higher concentrations of chlorhexidine should be investigated.

Notes: Abstract This study investigated the efficacy of a 0.1% chlorhexidine preparation as an aid to a basic oral hygiene programme comprising only baseline root and crown debridement, instruction in bass brushing without emphasis on interdental cleaning, and pulsated mono-jet subgingival irrigation. Baseline data for plaque index, papilla bleeding index and probeable pocket depth were similar in both test and control groups. Mean values for all 3 parameters were clearly lower in the chlorhexidine group, both at the end of the period of active treatment and up to 2 months thereafter. These differences were statistically significant for P1I at day 28, FBI at day 56 and PPD at days 56 and 84, but not at day 168. Proportionately more sites generally showed improvement in the chlorhexidine group at all times. It was concluded that 0.1% chlorhexidine significantly enhances the effects of the practical oral hygiene regime described.

Notes: Abstract In this study, 11 permanent teeth and their associated soft tissues from an 11-year-old boy with PLS were examined. Plaque, cementum and periodontal tissues were examitied by scanning (SEM) and transmission electron microscopy (TEM), Except for depressed lymphocyte transformation, there were no abnormal haematological data. Local findings included abnormally thin cementum, extensive destruction of the periodontal ligament were still attached to the root, and severe inflammation of the soft tissues. Few bacteria were found in any of the soft tissue layers. The apical border plaque was restricted to gram- cocci and rods. The features observed in this case of PLS may indicate primary defects of cementum or ligament attachment, or disruption of fibroblast and cementoblast function due to the rapid advance of the disease process. Lack of bacterial invasion in the pocket soft tissue casts doubt on its involvement in the present case of severe periodontitis. The restricted range of morphotypes observed suggests a limited range of associated organisms. Further research is required to clarify the rôle of the host response and to identify the organisms involved.

Notes: Abstract The purpose of this study was to determine the susceptibility to chlorhexidine of a range of bacteria which may be isolated from subgingival plaque. In addition, the effect of chlorhexidine on the survival of bacteria in subgingival plaque samples from patients with chronic inflammatory periodontal disease was investigated. The minimum inhibitory concentration (MIC) of chlorhexidine for 52 strains of bacteria ranged from 8 to 500 μ/gml. The modal value of the MIC was found to be 62 μ/gm/l, 64% of the strains tested being inhibited at this concentration. A concentration of 250 μ/g/ml of chlorhexidine inhibited the growth of all bacteria in the 25 subgingival plaque samples investigated. The MTC of chlorhexidine for the samples ranged from 31 to 250 μ//g/ml, the modal value being 125 μ//g/ml.