DH 209 Nutrition Exam

Correct Answer:

B. Approximately 50 different species of microorganisms compose the microflora.

Explanation of the Correct Answer:

The microflora in the colon, also known as the gut microbiota, consists of hundreds of different species of microorganisms, not just around 50. There are actually thousands of species that live in the colon, including bacteria, fungi, and other microorganisms. The number of species is far greater than the 50 species stated in option B.

Why the Other Options Are Correct:

A. Vitamin K and numerous B vitamins are synthesized by the microflora.

This statement is true. Certain bacteria in the colon help synthesize important vitamins, including vitamin K and several B vitamins (such as B12, biotin, and folic acid), which are important for various bodily functions. These vitamins are absorbed by the body from the colon.

C. Microflora inhibit pathogenic bacteria.

This statement is true. The gut microbiota plays a critical role in protecting the body from pathogenic bacteria by outcompeting them for nutrients and space, producing substances that inhibit pathogenic growth, and stimulating the immune system to respond to harmful invaders. This is one of the reasons why maintaining a healthy microbiota is important for overall health.

D. Microflora break down substances that human enzymes are unable to digest.

This statement is true. The microbiota in the colon helps break down complex carbohydrates, fiber, and other substances that human digestive enzymes cannot process. This process produces gases, short-chain fatty acids, and other metabolites that benefit human health.

Correct Answer:

B. False

Explanation of the Correct Answer:

The statement is false because tin itself is not the active trace mineral responsible for the effectiveness of topical fluoride formulations. Instead, it is stannous fluoride, a compound containing tin, that is sometimes used in fluoride products. However, the effectiveness of topical fluoride primarily depends on the fluoride ion itself, not the presence of tin as a trace mineral. Furthermore, fluoride compounds like sodium fluoride (NaF) and acidulated phosphate fluoride (APF) are the most commonly used in effective topical fluoride treatments, and these do not involve tin. While stannous fluoride (SnF₂) does provide anti-caries benefits and some additional antibacterial effects because of its tin component, tin alone as a trace mineral is not a standard ingredient or independently responsible for fluoride efficacy. Therefore, the statement as written is inaccurate.

Why the Other Option Is Incorrect:

A. True

This is incorrect because, although stannous fluoride contains tin, it is not the tin itself that makes topical fluoride formulations effective. The fluoride ion is the critical factor in preventing dental caries. Tin may provide some additional antibacterial properties in stannous fluoride formulations, but referring to "the trace mineral tin" alone as an effective component of fluoride treatments is misleading and incorrect.

Summary:

The statement is false. Tin itself is not the effective agent in topical fluoride formulations; rather, fluoride compounds, with fluoride ions being the key active ingredient, provide the caries-preventive benefit. While some formulations use stannous fluoride, the fluoride—not the tin trace mineral—is responsible for the primary therapeutic effect.

Correct Answer:

B. Cholesterol intake is essential.

Explanation of the Correct Answer:

Cholesterol intake is not essential because the body can synthesize all the cholesterol it needs. The liver and other cells in the body produce cholesterol, so it is not necessary to obtain cholesterol directly from the diet. While dietary cholesterol can influence blood cholesterol levels to some extent, the body’s production of cholesterol is the primary source, making dietary cholesterol intake non-essential.

Why the Other Options Are Correct:

A. Cholesterol is a precursor of vitamin D:

This is correct. Cholesterol is converted into vitamin D when the skin is exposed to sunlight. The conversion process involves the transformation of cholesterol into 7-dehydrocholesterol, which, upon exposure to UV light, is converted into vitamin D3 (cholecalciferol).

C. Cholesterol is a sterol derivative:

This is correct. Cholesterol is a sterol, which is a type of lipid molecule with a structure that includes multiple carbon rings. It is an important component of cell membranes and a precursor for the synthesis of hormones like steroid hormones, bile acids, and vitamin D.

D. Lipoproteins transport cholesterol in the blood:

This is correct. Lipoproteins are responsible for transporting cholesterol and other lipids (such as triglycerides) in the blood. Low-density lipoprotein (LDL) carries cholesterol to cells, while high-density lipoprotein (HDL) helps remove excess cholesterol from the bloodstream and transport it back to the liver for excretion.

Correct Answer:

B. Both statements are true

Explanation of the Correct Answer:

Both statements are accurate. Sugar alcohols, particularly xylitol, are classified as anticariogenic, meaning they help prevent dental caries (tooth decay). This classification is based on evidence showing that they do not contribute to acid production by oral bacteria and can actually inhibit the growth of Streptococcus mutans, the bacteria most associated with caries formation.

Furthermore, sugar alcohols stimulate salivary flow, which helps neutralize acids and wash away food particles, contributing to better oral hygiene. Increased saliva also delivers calcium and phosphate ions to the enamel, supporting remineralization of early (incipient) carious lesions and inhibiting demineralization. Xylitol, in particular, has been shown in clinical studies to reduce the incidence of cavities and promote oral health through these mechanisms.

Why the Other Options Are Incorrect:

A. The first statement is true, the second is false

This option is incorrect because the second statement is, in fact, true. Sugar alcohols do increase salivary flow and contribute to enamel protection by both inhibiting demineralization and promoting remineralization of early decay.

C. Both statements are false

This is incorrect because substantial research supports the anticariogenic properties of sugar alcohols and their role in promoting salivary activity and enamel health.

D. The first statement is false, the second is true

This is incorrect because the first statement is also true—sugar alcohols like xylitol, sorbitol, and mannitol are scientifically classified as anticariogenic based on their non-fermentable nature and positive effects on oral health.

Correct Answer:

C. Xerostomia

Explanation of the Correct Answer:

Xerostomia, or dry mouth, is not directly caused by gingival recession. Gingival recession involves the gradual loss of gum tissue from around the tooth, which exposes the tooth's root surface. Although xerostomia can lead to an increased risk of oral health problems such as tooth decay, it is not a direct consequence of gingival recession. Gingival recession primarily affects the gum line and the exposed roots of the teeth but does not directly impact the production of saliva, which is what causes xerostomia.

Why the Other Options Are Incorrect:

A. Abrasion of enamel and cementum

When the gums recede, the root surfaces of the teeth become exposed. This can lead to increased abrasion of the enamel and cementum (the protective layer on the root), especially when teeth are brushed aggressively or with abrasive substances. Abrasion occurs as the exposed root surfaces are more vulnerable to friction and wear.

B. Erosion of enamel and cementum

Enamel and cementum erosion can occur as a result of gingival recession because the exposed roots of the teeth are more susceptible to acid attacks. This can happen from acidic foods and drinks, or from acid reflux. As the enamel and cementum erode, it can lead to tooth sensitivity and increased risk of decay.

D. Root caries

Root caries are cavities that develop on the exposed root surfaces of teeth, which become more vulnerable as a result of gingival recession. The absence of enamel on the roots makes them more prone to the accumulation of plaque and bacterial growth, which leads to cavities. This is a significant risk factor for individuals with gingival recession, as the roots are not protected by enamel.

Summary:

Xerostomia is not a consequence of gingival recession, which affects the gums and exposes the tooth roots. The correct effects of gingival recession include abrasion, erosion, and root caries, as the exposed roots become vulnerable to wear, acid attacks, and bacterial activity.

Correct Answer:

A. Contains a small portion of solid foods

Explanation of the Correct Answer:

A full liquid diet consists solely of liquids or foods that are liquid at room temperature. It does not include solid foods or portions of solid foods, as it is specifically designed to be gentle on the mouth and suitable for patients who are recovering from procedures like periodontal surgery. The diet provides nutrition in the form of liquids, allowing for easier swallowing and minimal irritation to the surgical site.

Why the Other Options Are Incorrect:

B. May be required for the first 1 to 3 days

This is true. After periodontal surgery, a full liquid diet is often recommended for the first few days to ensure that the mouth remains undisturbed and to promote healing.

C. Contains high-protein, high-kilocalorie fluids

This is also true. Full liquid diets often contain high-protein and high-calorie fluids to ensure the patient gets adequate nutrition during the recovery phase, especially when their ability to consume solid foods is limited.

D. Provides food in a liquid form for patients unable to chew

This is true as well. A full liquid diet is typically used for patients who have difficulty chewing or swallowing, such as those recovering from oral or periodontal surgeries, to provide necessary nutrients in a form that is easy to consume.

Summary:

The exception is that a full liquid diet does not contain any solid foods, so the correct answer is "Contains a small portion of solid foods."

Correct Answer: B. Avoid eating for 2 hours prior to the dental appointment

Explanation of the Correct Answer:

Avoiding food intake for 2 hours prior to the dental appointment is recommended for patients with gastroesophageal reflux disease (GERD) because eating can stimulate acid production and increase the risk of acid reflux episodes during the appointment. Lying back in the dental chair can exacerbate reflux symptoms if the stomach is full, leading to discomfort, aspiration risk, or even erosion of the teeth from acid exposure. By avoiding food before the appointment, the patient minimizes these risks, ensuring greater comfort and reducing harm to oral structures.

Why the Other Options are Incorrect:

A. Brush their teeth immediately after a GERD acid exposure

This is incorrect. Brushing immediately after acid exposure can actually damage the enamel further. Acid weakens enamel, and brushing right afterward can erode it more severely. Instead, patients should be instructed to rinse with water or a fluoride mouthwash and wait at least 30 minutes before brushing to allow the enamel to remineralize and harden.

C. Drink orange juice before the dental appointment

This is incorrect. Orange juice is highly acidic and can worsen GERD symptoms and further expose teeth to acid, increasing the risk of erosion. Consuming acidic beverages before an appointment can promote reflux, cause discomfort, and harm oral health.

D. Enjoy spicy foods

This is incorrect. Spicy foods are known GERD triggers. They can relax the lower esophageal sphincter (LES), promote acid reflux, and worsen GERD symptoms. Patients with GERD are typically advised to avoid spicy foods to prevent flare-ups and related oral or gastrointestinal discomfort.

Summary:

The dental hygienist should advise the patient with GERD to avoid eating for at least 2 hours before the dental appointment to reduce the risk of reflux and protect both the patient's comfort and oral health. Immediate brushing after acid exposure, consuming acidic beverages like orange juice, and eating spicy foods are inappropriate recommendations because they can exacerbate GERD symptoms and cause further oral and esophageal damage.

Correct Answer:

D. Coconut oil

Explanation of the Correct Answer:

Coconut oil is known for being the most saturated fat among the options listed. About 90% of the fat in coconut oil is saturated. This high level of saturated fat content makes coconut oil solid at room temperature, similar to other highly saturated fats like butter or lard. Despite its high saturated fat content, coconut oil is often touted for containing medium-chain triglycerides (MCTs), which some believe may have health benefits, but it is still considered high in saturated fat overall.

Why the Other Options Are Incorrect:

A. Soybean oil

Soybean oil is primarily composed of polyunsaturated fats, with only about 14% of its fat content being saturated. It is often used as a healthier cooking oil due to its lower saturated fat content and higher amounts of omega-3 fatty acids.

B. Olive oil

Olive oil is considered a monounsaturated fat with about 14-15% saturated fat. It is praised for its health benefits, particularly for heart health, and is a primary fat source in the Mediterranean diet. The majority of the fat in olive oil is oleic acid, a monounsaturated fat known to be beneficial for reducing LDL (bad) cholesterol.

C. Canola oil

Canola oil is mostly composed of monounsaturated fats and polyunsaturated fats, with only about 7% saturated fat. It is considered a heart-healthy oil due to its high levels of omega-3 fatty acids (ALA) and low levels of saturated fat.

Correct Answer:

D. Energy storage

Explanation of the Correct Answer:

Proteins are primarily involved in many vital functions such as muscle contraction, enzyme catalysis, metabolism regulation, and providing structural support to cells and tissues. However, energy storage is not a primary function of proteins. The body typically stores energy in the form of carbohydrates (as glycogen) and fats (in adipose tissue). While proteins can be used as an energy source when necessary (for instance, during prolonged starvation), their main roles are much more focused on structural, functional, and regulatory tasks rather than energy storage.

Why the Other Options Are Correct Functions of Protein:

A. Regulating metabolism

Proteins play a crucial role in regulating metabolism, especially through the action of enzymes and hormones. Enzymes are proteins that catalyze biochemical reactions, speeding up processes like digestion and cellular energy production. Hormones like insulin are also proteins and help regulate metabolic processes such as blood sugar control.

B. Muscle contraction

Proteins such as actin and myosin are directly involved in muscle contraction. These proteins interact to produce the force needed for muscles to contract and perform movements, making muscle contraction one of the key roles of proteins.

C. Catalyzing reactions

Enzymes, which are proteins, catalyze chemical reactions in the body. This is one of the most important functions of proteins, as enzymes speed up necessary metabolic reactions such as digestion, energy production, and biosynthesis.

E. Providing structure

Proteins provide structural support to cells and tissues. For example, collagen is a structural protein found in connective tissues, skin, and bones. Similarly, keratin provides structure to skin, hair, and nails. Actin and tubulin are structural proteins that form part of the cytoskeleton, giving cells shape and support.