PREVENTIVE DENTISTRY AND NUTRITION

It is known that bacteria in dental plaque uses the nutrients in sugary type foods to produce acids. (Dental plaque is discussed in chapter 5, "Oral Pathology," and in Dental Technician, Volume 2, chapter 3, "Preventive Dentistry.") Foods that contain carbohydrates (high sugar content) are referred to as being cariogenic (conducive to the production of dental caries). Dental caries may start when poor oral hygiene is present. The decay process begins when dental plaque and the acid produced from cariogenic foods are left on the teeth for extended periods. Eventually, the acid demineralizes or breaks down enamel and dentin.

To reduce the possibility of dental decay, you should limit the ingestion of sweets to mealtime, and brush and floss thoroughly after meals. Some of the less cariogenic snack foods include fruits and vegetables. However, the least cariogenic snack foods are limited to skim milk, sugar free gum, sugarless soft drinks, sugarless gelatins, and a few others. Ideally, caries may be avoided by properly brushing and flossing right after eating.

CHAPTER 9 INFECTION CONTROL

Infection control involves taking steps to prevent the spread of infectious agents. Your command will develop standard infection control policies and written protocols following BUMEDINST 6600.10. COs and OICs must appoint in writing an infection control officer (ICO) to assist in implementing the infection control program. Material in this chapter and in chapter 10 are taken from BUMEDINST 6600.10, Dental Infection Control Program. Some of the information may be different from what your command policies and procedures are for infection control. COs and OICs may adapt the policies and procedures from BUMEDINST 6600.10 to meet their local conditions and criteria. Compliance with BUMEDINST 6600.10 is mandatory. If your command has significant variations from BUMEDINST 6600.10, the ICO must document in the infection control manual the reasons for those changes.

All dental personnel must be aware of sources and methods of transmission of pathogenic micro-organisms and infectious diseases. The emergence of the human immunodeficiency virus (HIV) epidemic, along with recent reports about health care workers who have acquired an HIV infection through occupational exposure, has generated much fear and worry within all the health professions, including dentistry. Healthcare personnel are caught in a conflict between concern for their patient's needs on the one hand and fear of acquiring HIV infection on the other.

Adding to this dilemma is the problem of the hepatitis virus (HBV) infection, a major infectious occupational health hazard in all the healthcare professions. Each year, several thousand healthcare workers become infected with the HBV. The Center for Disease Control (CDC) estimates that HBV infection in healthcare personnel actually results in some 600 hospitalizations and 200 deaths annually. These concerns have led to a renewed interest in the problem of infection control in the dental health care environment.

CLASSIFICATIONS OF MICRO-ORGANISMS

Microbiology is the study of microscopic life forms referred to as micro-organisms. They are so small that they can only be seen with the aid of a microscope. Micro-organisms are always present in our environment; most live in warm, dark surroundings where adequate food supply exists. The oral cavity is one such area where enormous numbers of micro-organisms commonly exist and multiply. A pathogen is an organism capable of causing disease. Disease producing organisms are said to be pathogenic. Other micro-organisms that are not considered pathogenic can produce infections under favorable conditions. Micro-organisms are classified as bacteria, bacterial spores, viruses, protozoa, and fungi.

BACTERIA

Bacteria are one-celled plants that lack chlorophyll (the chemical that provides the green coloring to plants). A single drop of water may contain as many as two billion medium-sized bacteria. Some diseases caused by bacteria are dental decay, periodontal disease, and tuberculosis.

The three main types and shapes of bacteria are as follows:

1. Cocci\spherical and shaped like small beads

2. Bacilli\rod-shaped

3. Spirochetes\spiral-shaped

Gram Positive and Gram Negative Bacteria

Certain antibiotics treat different types of bacterial infections. A liquid dye called gram stain is used on the bacteria to determine if they are gram negative or gram positive.

Bacteria that are stained by the dye and turn a dark purple color under microscopic study are called gram-positive bacteria. If no color exists after staining and viewing, the bacteria is called gram negative. A dental officer may submit a bacterial culture to the medical laboratory to determine if it is gram positive or negative before prescribing an antibiotic to treat an infection.

Bacterial Spores

Bacteria are very resistant to all environments. A protective coating on the surface helps the bacteria evade the defense mechanisms of the body and generally makes it more durable.

Not all bacteria will take on the form of a spore's shell-like coating to withstand unfavorable conditions. Bacteria in a spore state remain alive but passive, and they are resistant to the effects of heat, drying, and most bactericidal chemicals. They will remain capable of becoming virulent (strongly pathogenic) again under favorable conditions. However, under unfavorable conditions, they will either die or remain dormant in a spore state until another opportunity for growth presents itself.

Viruses

Viruses are micro-organisms that are much smaller than bacteria. Viruses vary in size, from being the size of a single protein molecule to the size of a more complicated bacterial cell. They can be so small that they can be seen only through an electron microscope.

Viruses cannot live long or reproduce outside of a living body (host). They must be able to enter and live in specific cells. For descriptive purposes, they are customarily divided into three subgroups, based on host specificity:

1. Bacterial viruses

2. Animal viruses (including those that attack humans)

3. Plant viruses

Some of the most common diseases caused by viruses are colds, smallpox, measles, rubella, herpes simplex, AIDS, infectious hepatitis, and serum hepatitis. Viruses are usually not affected by therapeutic treatment with antibiotics. Generally, therapeutic treatment is not used to combat a viral infection, but used to treat a secondary bacterial infection that may develop.

Most viruses are susceptible to immersion in boiling water for at least 20 minutes. There are two major exceptions to this rule, infectious hepatitis and serum hepatitis. Because of these exceptions to heat resistance, autoclaving for a minimum of 20 minutes at 270F, or dry heat sterilization for 90 minutes at 320F are the only safe procedures for control of these two viruses. PROTOZOA

Protozoa are single-celled animals that do not have ^{a rigid cell wall.} Some protozoa cause parasitic diseases but not all are pathogens. Most species are harmless, living on dead organic matter or bacteria. Protozoa that are pathogenic survive freely in nature and must be spread by a carrier.

Most protozoa pass through a life-cycle, meaning that they have definite stages of development. These stages vary for each species and are usually very complicated. Malaria is an example of a disease that is caused by protozoa.

FUNGI

Fungi, like bacteria, are plants that lack chlorophyll. They are free-living organisms that are smaller than protozoa. Mold and yeast forms of fungi have firm cell walls and resemble plants more than animals.

Molds usually form cells in long chains or threads that grow into tangled masses. Some threads of the mass bear clusters of seedlike spores that, when dry, are easily blown into the air like dust. Each microscopic seed is capable of growing new mold upon settling in a suitable place. Mold spores are easily destroyed by heat. The most common infections in humans because of mold are athlete's foot and ^ringworm. The mold penicillium is very common in nature and contributes to the spoilage of food. The drug penicillium is derived from this mold.