Granulocyte elastase activity and PGE2 levels in gingival crevicular fluid in relation to the presence of subgingival periodontopathogens in subjects with untreated adult periodontitis

This study aimed to determine the association between the levels of granulocyte elastase and prostaglandin E2 (PGE2) in GCE and the concomitant presence of periodontopathogens in untreated adult periodontitis (AP). GCF and subgingival plaque were sampled by paper strips and paper points respectively, from various periodontal sites in 16 AP subjects. Granulocyte elastase activity in GCF was analyzed with a low molecular weight substrate specific for granulocyte elastase, pGluProVal-pNA, and the maximal rate of elastase activity (MR-EA, mAbs/min/site) was calculated. PGE2 levels in GCF were determined by radioimmunoassay. 5 species-specific DNA probes were used to detect the presence of A. actinomyceterncomitans (A.a., ATCC 43718), B. forsythus (B.f, ATCC 43037), P. gingivalis (P.g., ATCC 33277), P. intermedia (P.i., ATCC 33563), and T. denticola (T.d., ATCC 35405), with a sensitivity of 10(3) cells/paper point. No A.a. was detectable from all sites sampled. The predominant combination of species detected was B.f., P.g., P.i. & T.d. and it was significantly higher at periodontitis sites (68%) than at healthy (7%) or gingivitis sites (29%) (p<0.05). Overall, MR-EA values were strongly correlated with PGE2 levels (r=0.655, p<0.001), especially at these periodontitis sites co-infected by B.f., P.g., P.i. & T.d. (r=0.722, p<0.001). The periodontitis sites co-infected by the 4 species were observable from 15 subjects. These sites were sub-grouped into 8 subjects with a high MR-EA and 7 subjects with a low MR-EA. The PGE2 levels in the high MR-EA group were significantly higher than in the low MR-EA group (p<0.05). No significant differences in clinical or bacterial data were found between the two groups. While within the high MR-EA group, similar results were found between the paired periodontitis sites in each subject with highest and lowest MR-EA values. This study shows that the local host response to bacterial challenge in untreated periodontal pockets is diverse in terms of the intensity of inflammatory response measured by granulocyte elastase and PGE2 levels in GCE A more thorough evaluation of the risk for active periodontal disease may involve the combined approaches to the test of the dynamic bacteria-host relations.

Dentistry's development in Hong Kong

The history of dentistry in Hong Kong is described from the time prior to the colonisation by the British to the present day. With the imminent, and historic, hand over of the present territory from British to Chinese rule on 30 June 1997, the authors also touch on the future of oral care in Hong Kong.

Comparison of modes of oral hygiene instruction in improving gingival health

195 Hong Kong Chinese employees from a single company participated in a 10-month longitudinal study on the effects of various modes of delivery of oral hygiene messages on their gingival health. Subjects were allocated to one of the following modes of oral hygiene education: (1) personal instruction; (2) self-education manual; (3) video; (4) a combination of 2 or more of these modes of instruction. Scaling or any other form of periodontal treatment was not given throughout the study period. Full mouth clinical examinations were carried out using a Williams Periodontal probe to examine for the presence or absence of plaque and bleeding on probing from the gingival sulcus. At 2 weeks, 4 months and 10 months, results showed significant reductions in the mean % of plaque and bleeding when compared with baseline. No significant differences were found between the groups given the various modes of oral hygiene education. The study does confirm the effectiveness of oral hygiene alone in improving gingival health, but the lack of difference in the outcome of various oral hygiene education approaches indicates that the mode of instruction is not crucially important to the end result. However, it has to be acknowledged that improvement in oral hygiene may be related to factors other than the oral hygiene programme itself. The findings have significant implications in oral health promotion programmes to improve the periodontal status of the local community.

Predominant cultivable microflora of supragingival dental plaque in Chinese individuals

The aim of this study was to determine the predominant supragingival cultivable bacterial flora in Chinese individuals, using the experimental gingivitis model. A total of 11 healthy dental students, mean age 22.5 years (range 20-25) were recruited. All were provided with once-a-week dental prophylaxis and oral hygiene reinforcement for 3 weeks to ensure gingival health. In the fourth week, after prophylaxis, the participants entered a 14-day period without any plaque control. A plaque sample was collected at days 1, 3, 7 and 14 from the buccal surface of the upper right canine, second premolar, first premolar and first molar, respectively. Each sample was then dispensed in tryptic soy-broth transport medium and grown anaerobically to obtain pure cultures, which were subsequently identified. Results showed that Gram-positive cocci and rods were the predominant cultivatable species (51-61%) in the samples throughout the 14-day period; with time there was a decreasing percentage of cocci and an increasing percentage of rods. Gram-negative cocci and rods increased in proportion with the plaque age (11-37%). Streptococcus spp. were the predominant Gram-positive cocci while Actinomyces were the predominant Gram-positive rods isolated. Fusobacterium and Capnocytophaga spp. were the two most frequent Gram-negative anaerobic rods cultured. The results compared with those from other analogous studies from the West suggest the possibility of interracial differences in supragingival plaque flora.

Comparison of various modalities of "simple" periodontal therapy on oral cleanliness and bleeding

550 Chinese employees of both sexes aged 25-44 from an industrial organisation participated in a 16-month longitudinal study. Subjects were divided into 4 groups: an oral hygiene group (group A), a scaling group (group B), an oral hygiene + scaling group (group C) and a control (group D). The experimental subjects were examined at baseline, 2 weeks, 4 months, 10 months and 16 months. After 10 months, group A received scaling while group B was given oral hygiene instruction for the 1st time. The control group did not receive any treatment until completion of the programme. At 16 months, all 3 experimental groups had significantly lower plaque and bleeding scores than the control. The plaque and bleeding levels of the experimental groups were lower at all review appointments when compared with baseline. Some variations in the clinical parameters were found between groups at 2 weeks, 4 months and 10 months. The scaling + oral hygiene group showed the best response. Although a proportion of subjects showed a substantial improvement in bleeding scores following scaling, the significant resource implications in providing such treatment has to be considered in planning community health programmes to promote periodontal health, wherein oral hygiene education must still have the highest priority.

The Hong Kong adult oral health survey--1991: background, study population, and methods

This second adult oral health survey was conducted with the following main aims: 1) to describe the oral health conditions and to analyse the oral health care needs and demands of 65-74-yr-olds in Hong Kong, and to propose appropriate strategies for meeting their needs in the light of societal obligations; 2) to describe the oral health conditions and to analyse the oral health care needs and demands of 35-44-yr-olds in Hong Kong with special emphasis on assessment of changes in this age group since 1984 (when the first adult oral health survey was conducted); 3) to assess the impact of sociodemographic and dental care system factors on the oral health status of selected adult age groups: and 4) to utilize survey data to refine curriculum development and research strategies in the Faculty of Dentistry, as well as in the proposal of appropriate action to governmental committees on dental health policy. For enhanced comparability with the previous study, the 35-44-yr-olds were selected from the same geographic areas of Hong Kong Island. Multistage cluster sampling was used to recruit the study population, defined geographic units and addresses being used as the starting-point. A sample of 398 subjects was selected, of whom 93% were both interviewed and clinically examined. The 65-74-yr-olds were recruited from housing estates in all principal areas of Hong Kong, yielding a sample of 559 subjects, of whom 96% were both interviewed and clinically examined.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of supragingival plaque in the control of progressive periodontal disease. A review

Levels of supragingival plaque and calculus have been related to progressive periodontal disease, and control of supragingival plaque in conjunction with professional tooth cleaning subgingivally forms the basis for the management of progressive periodontal disease. However, the contribution towards the management of progressive periodontal disease brought about by supragingival plaque control alone is not clear. There are studies which address, directly or indirectly, the contribution of supragingival plaque control alone towards the management of progressive periodontal disease. The effects of supragingival plaque control alone have been evaluated clinically, histologically and microbiologically, and taken together, the evaluations suggest that these effects may not be as marked as when professional subgingival tooth cleaning is also performed. These studies, however, given the patterns of periodontal disease found in adults in many communities, can form the basis for advocating high individual levels of supragingival plaque control as a community measure in the management of periodontal disease. Further long-term investigations into this approach may be warranted.

Emigration tendencies among Hong Kong Chinese dentists--1990

A postal questionnaire survey was conducted in April-May 1990 among 1223 Hong Kong Chinese dentists resident in Hong Kong to ascertain their plans for emigration from the Territory, as there were no data on emigration trends among dentists. A response rate of 47 per cent was obtained. Only 7 per cent of respondents definitely did not plan to emigrate and 47 per cent planned definitely or hopefully to emigrate, mostly in the years prior to 1997. Canada, Australia and the United States of America were the destinations most commonly cited by those planning to emigrate, and only one-quarter of these have any plans to return to Hong Kong. It was concluded that the emigration and return of Hong Kong dentists would influence workforce planning in the territory, and thus should be monitored.

Reasons given for tooth extraction in Hong Kong

Two hundred and seventy dentists, systematically selected from the membership lists of the Hong Kong Dental Association, were sent forms on which they were invited to record the reasons for tooth extraction in all patients aged 16 years and above over a period of five to six weeks. Third molars were excluded. Fifty-five per cent of the recording sheets dispatched were returned with usable data. Data were provided on 8516 extractions performed for 6331 patients. Overall caries was the reason given for 60 per cent of extractions; periodontal disease for 28 per cent; prosthetic indications for six per cent; trauma (which included tooth wear) for four per cent; and orthodontic and other reasons for two per cent. Extractions for periodontal reasons were more common in those aged 40 years and above, but periodontal disease did not exceed caries as a reason for extraction even in those aged 60 years and over. The tooth type most frequently extracted was the first molar. Mandibular incisors were the teeth most commonly extracted for periodontal reasons. In this community, which has benefited from water fluoridation since 1961, caries was the dominant reason given by dentists for tooth extractions in all age groups of the subjects studied.

Sex differences in the periodontal status of Hong Kong adults aged 35-44 years

Epidemiological studies on periodontal diseases conducted in many countries employing different indices have generally shown advanced periodontal destruction to be more prevalent in adult males than in adult females. The 1984 Hong Kong survey of adult oral health, using the Community Periodontal Index of Treatment Needs (CPITN) to determine periodontal status, revealed that in males aged 35 to 44 years the prevalence of deep pockets was 23 per cent, compared with 9 per cent in females (P less than 0.01). Males had a mean of 0.4 sextants with deep pockets whereas females had a mean of only 0.1 sextants so affected (P less than 0.01). Females were found to have a significantly larger proportion of healthy sextants (P less than 0.01). The observed sex difference in disease prevalence may have been influenced by the fact that fewer teeth were present in the females, but it could not be explained by differences in reported oral hygiene measures and practices.

Conversion of a stable T-cell lesion to a progressive B-cell lesion in the pathogenesis of chronic inflammatory periodontal disease: an hypothesis

Changes in the host's immunological response or, alternatively, changes in the oral microflora have been implicated as possible mechanisms by which a stable lesion of chronic inflammatory periodontal disease may become a progressive lesion leading to tissue destruction and tooth loss. It has recently been established that the progressive lesion in humans can be unequivocally considered as a B-cell response. Circumstantial evidence exists which suggests that the stable lesion is in fact a T-cell-mediated mechanism. An hypothesis is presented to explain the change from a stable to a progressive state in terms of a shift from a predominantly T-cell lesion to one involving large numbers of B-cells. Mechanisms of this shift in cell populations are considered together with a discussion of possible means of preventing such a shift.

The immunopathogenesis of progressive chronic inflammatory periodontal disease

Natural, humoral and cellular immune mechanisms have all been implicated in the pathogenesis of chronic inflammatory periodontal disease. However, confusion still exists as to the role played by each of these immunological mechanisms. Recently, characterization of the cell types within the progressive lesion has been established, in which four recognizable zones were described. Immediately subjacent to the epithelium lining the periodontal pocket both polymorphonuclear leukocytes (PMN's) and macrophages were seen, while cells deeper in the tissues had the morphological appearance of lymphocytes. The majority of these lymphocytes had a B-cell phenotype although a few T-cells and macrophages were found. On the advancing front of the lesion the cells had the morphological appearance of plasma cells, the majority of which contained IgG. Other cells found in this region had the morphology of plasma cells yet contained no cytoplasmic immunoglobulin, but they did contain substantial amounts of lysosomal enzymes. Similar cells have previously been described in periodontal disease; their frequent association with fibroblasts may suggest that they are important in the pathogenesis. Deposits of IgG and fibrin were found in the fibrous tissue band surrounding the lesion. These results are reviewed and, although the zones described were not anatomically distinct, by describing the lesion in this way it was possible to establish a convenient model to explain the immunopathogenesis of progressive chronic inflammatory periodontal disease. In this respect, progressive chronic inflammatory periodontal disease in man should be considered as a B-cell lesion.

Depolarization of the tooth pulp afferent terminals in the brain stem of the cat

1. Tooth pulp afferent fibres belonging exclusively to the Adelta group were stimulated bi-polarly with electrical pulses applied to the dentine and the central effects of the stimulation were examined in the nucleus of the spinal trigeminal complex of anaesthetized cats.2. Field potentials evoked by single pulses to the upper or lower canine tooth pulp were explored over the nucleus of the spinal trigeminal tract in the region 5 mm caudally to the obex up to 8.5 mm rostrally to the obex. They were found to be restricted to a region of 5.5-8.5 mm rostrally to the obex, 4-5 mm laterally from the mid line, with a maximum amplitude at a depth of 5 +/- 0.5 mm.3. Antidromic action potentials were recorded from the tooth pulp afferents. The stimulating micro-electrode was inserted in the region of the medulla from which distinct field potentials could be recorded by orthodromic stimulation.4. Excitability of the central terminals of the tooth pulp primary afferents was increased when the test stimulus was preceded either by a conditioning volley in low threshold afferent fibres of the infraorbital nerve or in Adelta fibres of another tooth.5. Single pulses applied to the afferent fibres of the tooth pulp produced changes in the excitability of central terminals of the fast conducting afferent fibres of the infraorbital nerve.6. The greatly increased excitability of central terminals of tooth pulp primary afferent fibres was accompanied by a small decrease in their synaptic efficiency as estimated from the changes of the post-synaptic component of the field potential evoked by their stimulation.7. It is concluded that an analogous presynaptic control mechanism is present at the central terminals of the tooth pulp primary afferent fibres as is known for the fast conducting cutaneous system. But a difference in the specifity of the action from this afferent system is suggested. While activity from Aalpha fibres is very effective in evoking primary afferent depolarization at both fast conducting trigeminal fibres and slow conducting Adelta system, the Adelta fibre activity is effective only at the latter, and not at the former.