Knowledge of the human immunodeficiency virus among final year dental students

J. Dent. 1994;

-\ \Jl

22: 229-235

1

f-

-//

Knowledge of the human immunodeficiency virus among final year dental students* A. D. Gilbertt and N. M. NuttaIlS tDepartment of Dental Surgery 8 Periodontology and #Dental Dental Health, University of Dundee, Scotland, UK

Health Services

Research Unit, Department

of

ABSTRACT A sound basis of knowledge about HIV infection and AIDS is essential to allow students to develop as dentists who undertake appropriate measures during clinical practice. In addition, it is also likely that possessing appropriate information may instil confidence in their own ability to diagnose and then manage patients infected by HIV. A questionnaire designed to test the knowledge of final year dental students in the UK was completed by 60.5% of students in 15 out of the 16 dental schools in the UK Generally, the students rated the teaching they had received about cross-infection precautions, virology, sterilization practice and procedures and recognition of blood-borne virus risk groups as adequate or more than adequate. However, there was a lower degree of satisfaction expressed for instruction in the management ofblood-borne virus carriers and the performance of barrier dentistry. Most dental students were aware of the association of hairy leukoplakia, oral Kaposi’s sarcoma, oral candidiasis as a whole, and thrush as one clinical variant, with HIV infection but there was a much lower level of knowledge of erythematous candidiasis. HIV-associated salivary gland disease, oral melanotic hyperpigmentation and idiopathic thrombocytopenic purpura. This study highlights some important gaps in the knowledge of final year dental students about HIV and AIDS. KEY WORDS: J. Dent. 1994; 1993)

Cross-infection, 22: 229-235

Human

immunodeficiency

(Received 10 May 1993;

virus, Dental students’ knowledge reviewed

16 August

1993;

accepted

1 November

Correspondence should be addressed to: Dr A. D. Gilbert, Department of Dental Surgery and Periodontology, University of Dundee, Park Place, Dundee DDI 4HR, Scotland, UK.

INTRODUCTION The oral cavity is a body area where as many as 40 conditions or lesions associated with infection by the Human Immunodeficiency Virus (HIV) can occur’ and it is known that most AIDS patients have head and neck manifestations2. Oral manifestations are often early signs of HIV infection3, and may thus be useful prognostic indicators. Dentists may therefore play a major role in initial detection of HIV infection, and to fulfil both this responsibility and be able to carry out effective, clinical management of patients they need to be aware of and understand the significance of such conditions and lesions. It is to be hoped that dental students in their last year of training would be in possession of the most current *Presented at the International Association General Meeting. Glasgow. July 1992. a 1994 Butterworth-Heinemann 0300-57 12/94/040229-07

Ltd.

for Dental Research.

academic information regarding blood-borne viruses, be aware of the risk of virus transmission possible as a result of dental procedures and know about recommended cross-infection control procedures. Clinical practice based upon these principles is essential for the safety and well-being of dentists and their patients. Such knowledge may instil confidence in dentists about their own ability to manage patients they know to be infected by HIV, but who are otherwise well, and reduce the incidence of rejecting such patients. Furthermore, the entrance of students into the dental profession may be a significant route through which more recent research findings are disseminated into general dental practice. It is essential therefore that student knowledge is assessed so that any areas of deficiency may be addressed and teaching courses amended appropriately. The aim of this study was to assess UK final year dental students’

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Tab/e 1. Final year UK dental students’ evaluation of the teaching they had received on six topics

More than adequate Topic

(%01

*

Less than Adequate (So)

adequate (s’,l

None (%!

42

55

2

1

7

71

21

1

Sterilization practice and procedures

27

60

13

-

Barrier dentistry

11

54

29

6

Recognition of blood-borne virus risk groups

17

65

17

1

Management of blood-borne virus carriers

13

54

31

2

Cross-infection precautions Virology

knowledge of the virus, the association of lesions/ conditions with HIV, and cross-infection transmission routes for HIV.

Tab/e II. Final year UK dental students’ responses to three questions dealing with their academic knowledge of HlVand AIDS Question

MATERIALS

AND METHODS

Permission was sought from the deans of all the dental schools in the UK to contact their final year dental students. Each school was assured that no results relating to an individual student or school would be divulged. Contact was established with one member of staff in each school who supplied a list of names of the appropriate students in their institution. Each student was sent a numbered questionnaire in an envelope, which also contained a stamped addressed envelope to allow prompt return of the forms. The questionnaires were numbered to allow non-respondents to be identified so they could be sent a second questionnaire and a reminder note. Complete confidentiality of all the returned forms was assured.

%

A: ‘Which host defence cells are primarily affected in AIDS?’ Macrophages B-lymphocytes Phagocytes T-lymphocytes Don’t know

92 1

B: ‘If an individual is demonstrated to antibodies are they’ Definitely suffering from AIDS? Immune to HIV infection? An HIV carrier? Don’t know

2 3 91 4

2 5 -

carry anti-HIV

C: ‘What is theaverage time interval between contracting HIV and the production of antibodies to it?’ Less than 6 weeks 6-l 2 weeks 13-24 weeks 24 weeks-5 years Don’t know

8 28 25 24

15

RESULTS All but one of the 16 schools contacted agreed to take part. A total of 447 replies were received from the 739 students supplied with a questionnaire, giving a response rate of 60.5%.

the students felt that their training in the management of blood-borne virus carriers and the performance of barrier dentistry was less than adequate. Academic

Evaluation

of teaching

The students were asked to grade the adequacy of the teaching which they had received on six subjects relating to the management of potential high risk patients (Table I). Most students felt their education concerning crossinfection precautions, virology, sterilization practice and procedures, barrier dentistry, recognition of blood-borne virus risk groups and the management of blood-borne virus carriers was adequate or more than adequate. Nevertheless, the results suggest that around one-third of

knowledge

of AIDS/HIV

Students were asked a series of academic questions about HIV infection (Table II); 91% of the students said that an individual carrying anti-HIV antibodies would be an HIV carrier and 92% said that T-lymphocytes were the host defence cells primarily affected in AIDS. There was less agreement about the average time interval between contracting HIV and the production of antibodies to it: 28% of students chose the range 6-12 weeks, with 24% choosing 24 weeks to 5 years, and 15% stating they did not know.

Gilbert and Nuttall:

Student’s

knowledge

of HIV

231

Table 111.Final year UK dental students’ knowledge of lesions and conditions in association with HIV Virtually exclusive to HIV

Associated with HIV (in some cases)

Unassociated with HIV

Don’t know

lesion/condition

I%)

I%)

I%)

(%)

Hairy leukoplakia (I) Oral Kaposi’s sarcoma (I)

64 89

33 10

;

2 1

3 3 2 5

95 92 57 25

1 4 32 19

A 51

Salivary gland enlargement (II) Xerostomia (II)

66 40

23 44

10 15

Oral melanotic hyperpigmentation (Ill) Idiopathic thrombocytopenic purpura (II) Seborrhoeic dermatitis

42 40 23

;: 23

Crohn’s disease Gorlin-Goltz syndrome Psoriasis

5 3 10

84 70 70

Oral candidiasis (I) Oral thrush (I) Erythematous candidiasis (I) Candida endocrine syndrome

1

:27 53 10 26 20

Where appropriatethe lesions/conditionshavealsobeen classifiedaccordingto the revisedclassificationof HIVassociated oral lesions? I, lesions strongly associated with HIV infection; II, lesions less commonly associated with HIV infection: III, lesions possibly associated with HIV infection.

Association of lesions/conditions HIV infection

with

Students were asked to designate each of a randomly ordered list of lesions/conditions as being either virtually exclusive to HIV, associated with HIV (in some cases) or unassociated with HIV (Table 111).Where appropriate the lesions/conditions have also been classified according to the revised classification of HIV-associated oral lesions compiled by a 15-member working party in August 19904. The association between HIV and hairy leukoplakia was recognized by 97% of respondents and just under twothirds (64%) thought the association was virtually exclusive. Almost all the students (99%) recognized the link between HIV and Kaposi’s sarcoma and here 89% thought the association was virtually exclusive. Most students (95%) recognized that oral candidiasis (as a generic term) is association with HIV in some cases with almost as many (92%) stating that one variant, thrush, is similarly associated. Another clinical variant, erythematous candidiasis, was thought to be HIV associated in some cases by only 57% of respondents with 32% being positively convinced that no such link.existed. Two-thirds of the students (66%) thought there was an association in some cases between salivary gland enlargement and HIV infection while only 40% of them thought that xerostomia was similarly associated. Less than 50% of respondents recognized that a link does exist between HIV and encephalopathy. oral melanotic hyperpigmentation, idiopathic thrombocytopenic purpura and seborrhoeic dermatitis, but at least 70% knew that Crohn’s disease, Gorlin-Goltz syndrome and psoriasis have no HIV association.

Table IV. Final year UK dental students’ views on potential transmission routes of HIV Potential transmission

route

%

Your unbroken skin in contact with unbroken skin of HIV+ve patient Your unbroken skin in contact with blood of HIV+ve patient Your unbroken skin in contact with saliva of HIV+ve patient Your cut skin in contact with unbroken skin of HIV+ve patient Your cut skin in contact with blood of HIV+ve patient Your cut skin in contact with saliva of HIV+ve patient Inhalation of aerosol-containing blood of HlVfve patient Inhalation of aerosol-containing saliva of HlVfve patient Don’t know

Potential

3 13 6 5 99 64 76 1 1

cross-infection

transmission

routes

Respondents were asked to identify potential crossinfection transmission routes for HIV. The results are shown in Table IV which is divided into three sections for ease of interpretation. In the first of these, the respondent’s skin is assumed to be unbroken, in the second the respondent’s skin is assumed to be broken and the third deals with aerosol inhalation. Few respondents thought that their unbroken skin in contact with the unbroken skin (3%). blood (13%) or saliva

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(6%) of an HIV-positive patient represented a crossinfection risk. However, contact of their own cut skin with the blood or saliva of an HIV-positive patient was deemed by the majority of respondents to be a potential crossinfection transmission route. There was a perceived difference in the risk posed by the two body fluids in this way however, with 99% citing blood as a potential crossinfection vector, while only 64% cited saliva. The relative risk of aerosol inhalation as a means of cross-infection was deemed to be less than cut skin contact but with the differential in perceived infectivity between an HIV-positive patient’s blood and saliva being maintained. Seventy-six per cent of respondents thought inhalation of an aerosol-containing blood from an HIVpositive patient represented a risk while only one-third (33%) perceived a saliva-containing aerosol from such a patient to be a potential cross-infection transmission route. Only 1% of respondents stated ‘don’t know’.

DISCUSSION The method All results from questionnaires are highly dependent on the precise questions asked which means that interpretation of the results must be treated with caution. Comparison with the results of other surveys which differ in sample size, respondent target and content is virtually impossible. Despite these shortcomings, however, this is the only method which could be used to gain a snap-shot perspective on the nationwide state of knowledge of final year dental students. Forty per cent of the students who were sent a questionnaire failed to complete the questionnaire despite being re-contacted on two occasions. There may be many reasons for this, including apathy induced by repeated requests to fill in questionnaires, but another explanation may be lack of confidence about the topics tested, even though assurances were given that the results would be confidential. The results presented should therefore perhaps be looked on as probable overestimates of the general level of knowledge among final year dental students in 1991. Evaluation

of teaching

Generally, the students rated the teaching they had received very favourably. It is inevitable that the responses to the questions asked may, in part, reflect the abilities of the teachers involved and not just the subjects covered. However, the results of the questions posed showed that there was a lower degree of satisfaction expressed for instruction in the management of blood-borne virus carriers and the performance of barrier dentistry which may suggest students feel relatively less well prepared for the practical reality of treating high risk patients than they do about the theories underpinning it. This may reflect

lack of practical clinical experience in treating such patients which in turn may have produced some lack of confidence. or it may reflect unease or unwillingness to treat these patients at all. It is widely recognized that the number of known HIVpositive individuals is much smaller than the actual number infected and it is logical to assume that all practising clinicians will at times therefore unknowingly treat HIV-positive patients. Education that the occupational risk of contracting HIV is very 10w~.~is vital to ensure that dental treatment of high risk and/or HIV/ AIDS patients is not withdrawn or made difficult by dentists and that dentists themselves may provide such treatment in a rational way. Academic

knowledge

HIV appears specifically to attack T-lymphocytes resulting in a reduced T-helper cell count and thus a reduced Thelper/suppressor cell ratio. Sufferers of AIDS, the terminal event of HIV infection, may thus display anergy to skin testing, reduced mitogenic responses and increased susceptibility to many infections and otherwise rare tumours. The standard AIDS test relies upon detection of anti-HIV antibody. It is known that HIV can be carried simultaneously with the antibody and remain infective, thus the seroconversion does not indicate immunity but implies carrier status’. It is encouraging that at least 90% of students (93% and 90% respectively) recognized these facts. However, the respondents’ knowledge of the average time interval between contracting HIV and seroconverting was more disappointing. The average time to seroconvert has been estimated to be 2.6 monthsx with most infected persons being expected to seroconvert within 6-12 weeks of exposure’. Only 28% of students chose this option from those given. It is also known that 95% of individuals seroconvert within 5.8 monthslO. therefore the 24% of respondents selecting the 24 weeks-5 years option are overestimating the average seroconversion time. Furthermore, 15% stated they did not know, which suggests that many students may not understand when HIV testing might be expected to produce a positive result after. for example. a needlestick injury if a specific time was identified when infection with HIV may have taken place. Many students (78%) assessed the teaching they had received in virology as being at least adequate, suggesting that these individuals feel competent in this area of study (Table I). The results derived from this section of the questionnaire suggest that their knowledge is patchy and that some respondents’ self-confidence is, at least in part. misplaced, which may have clinical implications. Association of lesions/conditions with HIV infection

associated

Many HIV-associated lesions appear in and around the mouth so dentists may play a major role in initial

Gilbert and Nuttall: Student’s knowledge of HIV

detection of the infection and so provide vital diagnostic and referral services. Dental schools thus have a great responsibility to ensure that students are well trained in recognizing the signs and symptoms of HIV infection. This is particularly important as patients may be unaware of the presence or significance of any lesions and many, even if they have a high risk lifestyle, may have chosen not to be HIV tested and so may be unaware of their infection. Most students were clear that both Kaposi’s sarcoma (99%) and hairy leukoplakia (97%) are associated with HIV. However, 36% of respondents did not recognize the fact that hairy leukoplakia is virtually exclusive to HIVpositive individuals”. Indeed, in one study in Africa, the clinical finding of hairy leukoplakia was found to have a predictive value for the presence of AIDS or HIVinfection of 100% and 95% respectively’*. Thus there is great significance in the presence of hairy leukoplakia but this appears to be underestimated in the sample studied. Most respondents (89%) recognized oral Kaposi’s sarcoma as being virtually exclusive to HIV-infected individuals. Kaposi’s sarcoma rarely occurs in other instances, but when it does it is seen primarily in the seventh decade of life, mostly affecting the lower extremetiesij. It is important that Kaposi’s sarcoma is recognized, as it may be the first sign of HIV infection or may develop during the course of the disease14. From the early periods of the AIDS epidemic, candidiasis was also seen to be an important sign of the disease process and its progression. A substantial body of epidemiological data now emphasizes its high prevalence in HIV-infected personsi5. 16, with the frequency of candida isolation and clinical signs of candidiasis increasing with advancing HIV infection”. The responses in this study indicate that students probably recognize this for oral candidiasis as a whole and for thrush as one clinical variant but that there is a much lower level of knowledge for erythematous candidiasis. This is signiticant since a study has suggested that the erythematous form of candidiasis may precede the widely recognized pseudomembranous (thrush) form 18,although prospective surveillance studies are yet to be undertaken to confirm this observation. It is worrying that virtually a third (32%) of students said that no link existed between HIV and erythematous candidiasis, and in many ways this is worse than students recognizing that they do not know. It is probable, therefore, that the role ofboth the erythematous and hyperplastic variants of candidiasis in relation to HIV should be highlighted to all students if this important clinical sign is to be recognized. Candida endocrine syndrome was recognized as having no association with HIV by only 19% of students. Perhaps this was because the strong link of oral candidiasis as a whole with HIV was recognized by so many students and many became confused as to whether this was just another variant that could be associated. At least here the majority (52%) stated they did not know rather than getting it wrong. A number of lesions affecting the salivary glands have been associated with HIV infection. These lesions are

233

characterized by xerostomia and/or major salivary gland enlargement. It would appear from the results in Table II that many students appear to be unaware of this. Oral melanotic hyperpigmentation. idiopathic thrombocytopenic purpura and seborrhoeic dermatitis are all associated with HIV in some cases 19.Less than half the students recognized this, which is a concern, particularly as the first two conditions are listed in the Revised Classification of HIV-Associated Oral Lesions4. Furthermore, many students said that no association existed between oral melanotic hyperpigmentation, idiopathic thrombocytopenic purpura or encephalopathy and HIV, rather than saying they just did not know the answer. This is important as not every HIV-positive patient with oral symptoms will present with classic hairy leukoplakia, Kaposi’s sarcoma or thrush which are well recognized. Such knowledge is essential in order to be able to follow guidelines issued by the British Dental Association that HIV-positive patients who show oral manifestations of HIV disease should be referred for expert advice5. The majority of respondents did recognize that Crohn’s disease, Gorlin-Goltz syndrome and psoriasis had no association with HIV. This is encouraging as it is in some ways as important to recognize which conditions have no association with HIV as it is to recognize those which do, as wrong information in this regard could lead to patients being wrongly categorized, which could affect their access to treatmentzO.*i.

Potential

cross-infection

routes for HIV

The risk of occupational transmission of HIV via blood is real but statistically very small. Transmission to health care workers by occupational parenteral exposure to infected blood has been estimated to be less than 0.5% per exposure to HIV-infected blood.22. Such contact with blood was cited as a possible transmission route by virtually all respondents (99%) and similar saliva contact was cited as a transmission risk by almost two-thirds (64%) of those surveyed. The information regarding saliva as a transmission risk is much more uncertain. Antibodies to HIV of the classes IgG and secretory IgA are commonly found in the saliva of HIV-positive patients, resulting in the suggestion that saliva collection could be used as a convenient non-invasive means of HIV antibody screening23. The HIVvirus may also be recovered from the oral cavity but the mouth and its salivary secretions have not been demonstrated to transmit the virus as yetz4. Glandular saliva has even been shown to inhibit the infectivity of HIV** which may partially explain the infrequency of virus isolation from gland saliva and the lack of transmission found clinically. Thus while it is possible that the students may be expressing exaggerated concern about saliva from HIV-positive patients contacting their cut skin, it must be stated that it is generally accepted that all direct contact with HIV-positive body fluids should be regarded as potential transmission routes, even if no definitive proof of this risk has yet been

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found. Certainly the students rated blood as a more likely infective agent than saliva for both the cut skin and inhalation routes, and the inhalation route was regarded by them as less of a transmission risk than parenteral exposure. The risk of HIV transmission to clinicians with unbroken skin touching the unbroken skin, blood or saliva of an HIV-positive patient must be nil. The same is true of clinicians with cut skin contacting only the unbroken skin of an HIV-positive patient. However, 3%. 13%. 6% and 5% respectively of students considered these to be possible transmission routes. These answers may suggest that the students were worried about the practical possibility of their skin having small abrasions or cuts of which they themselves could be unaware. While in practical terms this is possible, the question asked specifically referred to the skin being definitively unbroken. These respondents may thus have a less than logical approach to the problem of cross-infection control, and again could reflect some unwillingness to treat such patients. Certainly, fears of personal risk in treating potential or actual HIV-positive/AIDS cases have been cited by dentists as a barrier to providing these patients with dental care 26. Adoption of universal crossinfection policies and education that the risks involved are small is a continuing requirement. The inflated perception of’ risk of viral infection which has been revealed among dental staff and students2’ may increase dentists’ uptake of precautionary measures but may also manifest itself in an unwarranted level of concern about treating known HIV carriers. Dentists should have an accurate picture of the current knowledge of the Human Immunodeficiency Virus in order to make rational and informed decisions about how to manage all dental patients.

References

6.

7 8.

9.

10

11

12.

13.

14.

1s.

CONCuJSlONS The study suggests there may be some significant gaps in the knowledge of some students about some of the oral lesions/conditions associated with HIV infection which may reduce their ability to provide appropriate diagnostic treatment or referral facilities for the patients who will depend upon them.

16.

17.

18. 19.

Acknowledgements We would like to thank the Deans of the dental schools of Belfast, Birmingham, Bristol, Cardiff, Dundee. Edinburgh, Glasgow, Guys, Leeds, Liverpool, The London Hospital, Manchester, Newcastle, Sheffield, and University College, London who allowed this study to be conducted. and the students and local contacts within these schools. The study was funded by the Scottish Office Home and Health Department, Grant K/OPR/15/2/4/F4, who do not necessarily share the views expressed in this article.

20.

21.

22.

23.

Samaranayake LP. Oral care of the HIV infected patient. Dent Update 1992; 19: 56-58. Schiodt M and Pindborg JJ. AIDS and the oral cavity. lnr J Oral Maxillofac Surg 1987: 16: 1-14. Scully C and Porter SR. Oral manifestations of HIV infection. Lancer 1988; i: 975-977. Challacombe S. Revised classification of HIV-associated oral lesions. Br Dent J 1991: 170: 305-306. British Dental Association. The Control of Cross-intection in Dentisrry. Advice Sheet A12. London: British Dental Association, 1991. Centers for Disease Control. Guidelines for prevention ol transmission of human immunodeficiency virus and hepatitis B virus to health-care and public-safety workers. Morb Mortal Week Rep 1989; 38: no S-6. Scully C and Cowson RA. Medical Problems in Den&q, 2nd edn. Bristol: Wright. 1987: p. 440. Longini IM, Claric WS and Byors RH. Statistical analysis of the stages of HIV infection using a Markov model. Stat Med 1989: 8: 831-843. Centers for Disease Control. Recommendations for preventing transmission of Human Immunodeficiency Virus and Hepatitis B Virus to patients during exposure-prone invasive procedures. Morbid Mortal Week Rep 1991; 40: no RR-8. Horsburgh CR, Ou C-Y. Jason J. Holmberg SD. Longini IM. Schable C. Mayer KH, Lifson AR, Schochetman G and Ward JW. Duration of human immunodeficiency virus (HIV) infection before detection of antibody. Lancet 1989; ii: 637-640. Greenspan D and Greenspan JS. Significance of oral hairy leukoplakia. Oral Surg Oral Med Oral Pathol 1992: 73: 151-154. Schiodt M, Bakilana PB and Hiza JF. Oral candidiasis and hairy leukoplakia correlate with HIV infection in Tanzania. Oral Surg Oral Med Oral Pathol 1990: 69: 591-596. Epstein JB and Silverman S. Head and neck malignancies associated with HIV infection. Oral Surg Oral Med Oral Pathol 1992; 73: 193-200. Beral V. Peterman TA Berkelman RL and Jaffe HW. Kaposi’s sarcoma among persons with AIDS: a sexually transmitted infection? Lancet 1990; 335: 123-128. Samaranayake LP and Scully C. Oral candidosis in HIV infection. Lancet 1989; ii: 1491-1492. Coleman D. Russel R. Harwood M, Malachy I’ and Shandley D. Clinical and microbiological analysis of oral candidosis in HIV-positive patients. J Dent Res 1989: 68: (abstr), 893. Korting HC. Ollert M, Georgii A and Froschl M. In vitro susceptibilities and biotypes of Candida afbicans isolates from the oral cavities of patients infected with human immunodeficiency virus. J Clin Microbial 1989; 26: 26262631. Pindborg JJ and Nielson H. Significance of oral lesions; oral candidosis. J Dent Res 1989; 68: (abstr), 859. Ficarra G. Oral lesions of iatrogenic and undefined etiology and neurologic disorders associated with HIV infection. Ora! Surg Oral Med Oral Path01 1992: 73: 201-21 I. Gerbert B. AIDS and infection control in dental practice: dentists’ attitudes. knowledge and behaviour. J Am Dent Assoc 1987; 114: 311-314. Hazelkorn HM. The reaction of dentists to members of groups at risk of AIDS. J Am Dent Assoc 1989; 119: 612-619. Scully C and Porter SR. The level of risk of transmission of human immunodeficiency virus between patients and dental staff. Br Dent J 1991: 170: 97-100. Shoeman RL. Pottathil Rand Metroka C. Antibodies of HIV in saliva. N En@ J Med 1989: 320: 1145-l 146.

Gilbert and Nuttall:

24. Centers for Disease Control. Update: universal precautions for prevention of transmission of human immunodeticiency virus. hepatitis B virus and other blood-borne pathogens in health-care settings. Morbid Mortal Week Rep 1988; 37: 377-382. 25. Fox PC. WolffA Yeh C-K, Atkinson JC and Baum BJ. Saliva inhibits HIV-I infectivity. J Am Dent Assoc 1988; 116: 635-637.

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26. Gerbert B, Maguire B and Badner V. Changing dentists’ knowledge, attitudes and behaviours relating to AIDS: a controlled educational intervention. J Am Dent Assoc 1988: 116: 851-854. 27. Samaranayake LP. Figueiredo HMJ. Rowland CA and Aitchison KA. A comparison of the attitudes of hospital dentists and dental students in Glasgow, UK and Los Angeles. USA towards treatment of AIDS and hepatitis B patients. Am J Dent 1990: 3: 9-14.

Abstracts

Marginal gap of recent light-activated restorative glass ionomers immediately after light activationeffect of setting shrinkage and shear bond strength. lrie M and Nakai H. Jap J Dent Mater 1993; 12:

790-794. The marginal gap, setting shrinkage and shear bond strength to tooth structure were determined for recently available light-activated restorative glass ionomers. Three light-activated glass ionomers and one composite were used. Investigations were performed immediately after light activation. In all cases, marginal gap was observed and an apparent correlation existed between marginal gap and setting shrinkage (r = 0.9997, P < 0.001). Marginal gap was influenced more by setting shrinkage than by shear bond strength. (12 references) H. Hisamitsu

Relation between the change of vertical dimension and the linguistic function in complete denture prosthesis. Gao ning et al. Pracr Oral Med 1993; 9: 230-234. Due to the change of vertical dimension, the subjective perceptibility, the objective judgement and the sonagram will change in complete denture wearers. These changes were analysed in 12 complete denture wearers in this research. The result showed that correct vertical

dimension will be useful to the restoration of the linguistic function and can shorten the time that patients spend on verbal adaptability on denture. Articulation will decrease whenever the vertical dimension is too high or too low. (9 references) Liao Fang-Gang and Yu Liu-Ning

A clinical study on a newly developed adhesive resin short-term assessment. system KB-1 00-a Hosoda H, lnokoshi S, Yamada T, Tagami J, Fujitani M, Takatsu T. Jap J Conserv Dent 1993; 36: 1305-I 323. This study was designed to evaluate the clinical performance of a newly developed adhesive resin system KB-100, which comprises a two-liquid-type surface conditioner and one-liquid-type light-cured bonding resin. Sixty-one cavities and 25 cases of root surface exposure without definite defect were restored with this system using restorative composites and/or low viscosity composites, A short-term detailed examination was performed and the following results were obtained. Preoperative hypersensitivity observed in 47 cases disappeared immediately after treatment except for two cases of severe preoperative sensitivity. The KB-1 00 system hardly showed any complication up to 3 months after treatment. (1 5 references) H. Hisamitsu