Medical Histories and Personal Protection
The first aim of this chapter is to examine the value of the patient’s medical history in preventing the transmission of infection during dental procedures. The second aim is to look at personal protection of dental personnel.
After reading this chapter, you should have an understanding of the use of the medical history and how personal protection is important in prevention of the transmission of infection.
Taking an accurate medical history is essential before any dental procedure, but often is not helpful for determining whether a patient is an infection risk. This is because many of the potentially infectious diseases are “silent” – the patient may not know they have contracted them. Thus, unless the patient reports that they have been diagnosed as carrying a specific infectious disease, the medical history may not be helpful in determining their infectious status. Many potentially infectious diseases are associated with prejudice and stigma, notably HIV, and infected patients may as a consequence be economical with the truth in giving their medical history. In addition, in many countries, patients are not obliged by law to disclose information about certain infectious diseases they know they carry.
One frequently asked question in taking medical histories is to ascertain a history of jaundice. Although this question can be helpful in determining whether a person has liver disease, which can affect, for example, bleeding time, it is rarely helpful in eliciting liver infections, such as hepatitis B or C. A history of jaundice can also be unhelpful, because it could have been caused by hepatitis A or E, conditions which are usually self-limiting and do not pose an infection risk in dentistry. Jaundice is usually a late stage in the progression of hepatitis B and C infections. It is therefore unlikely that carriage of hepatitis B or C would be elicited from a medical history, unless the patient has been diagnosed as having contracted them and reports them truthfully.
It is because the medical history may be non-contributory in determining whether the patient is an infection risk that standard precautions are used for all patients. Even if a patient does not report a significant diagnosed infection when the medical history is taken, if standard precautions are used, these should give protection against infection for all normal dental procedures.
Any information given to a dental professional during a medical history must be completely confidential. All staff must be aware of this absolute need for confidentiality. Worldwide there have been a number of cases of breaches of confidentiality that have resulted in legal redress.
Every dental practice should have a written and regularly updated infection control policy, which has been read and is adhered to by all members of staff (see Chapter 6 and appendices). It should be a condition of employment that all staff adhere to the policy. An example of an infection control policy is shown in Appendix 1. The policy should include a daily schedule of how to set up a surgery for various procedures (see Appendix 1). New members of staff should have full induction training in infection control (see Appendix 2) and should not learn just by observation during dental procedures. The compliance of all staff with infection control procedures should be regularly audited and discussed at practice meetings. In addition, all staff should periodically attend training sessions given by experts from outside the practice.
Countries vary in their legal requirements for pre-employment health checks for dental personnel. In some countries any personnel who have contracted HIV, hepatitis B, C or tuberculosis are prevented by law from doing, or assisting in dental operations. The evidence for preventing an untreated tuberculosis carrier from being involved in dental procedures is compelling, but after four weeks of a course of antituberculosis therapy they should not be any danger of transmission of infection. The case for barring a person who is infected with HIV is less conclusive, as highly active retroviral therapy should negate the very minimal risk of transmission. Many countries do not legally prevent HIV carriers from doing dental procedures, provided standard precautions are taken, appropriate medication used and regular health checks are done on the infected individual. Similarly hepatitis C has never been proven to be transmitted by dental personnel and it seems illogical to ban carriers from participating in routine dental procedures.
The main route for transmission of hepatitis B to dental personnel is from patient’s blood on instruments after sharps injuries. It is probably related to the number of virions present in the blood. This can be assessed by estimating the number of hepatitis B DNA copies present in a unit of blood. Some countries recommend that dental personnel, if they are doing invasive dental procedures, should not have greater than 103 virions per ml present in blood but this condition is not universally employed.
The value of pre-employment health checks for HIV and hepatitis C is therefore questionable, but there is some merit in ensuring that carriers of hepatitis B and tuberculosis do not engage in invasive dental procedures.
Successful immunisation against infectious disease is an essential part of personal protection in dentistry. The immunisations that are commonly recommended are shown in Table 2-1 and cover a range of bacterial and viral disease. Many of the immunisations listed in the table are routine vaccinations against infectious disease given in most developed countries to infants or adolescents, and are not especially applicable to dentistry. Some of these vaccinations are not given routinely in some countries; a good example of this is tuberculosis. The use of an avirulent tuberculosis strain in the bacille Calmette-Guérin (BCG) vaccine has not been accepted by all countries, as its efficacy of protection and longevity has been questioned.
|Disease||Route||Length of protection|
|Diphtheria||Intramuscular||Probably lifelong if given in infancy, but some authorities recommend re-vaccination in adolescence|