|
| A) | 5% | ||
| B) | 25% | ||
| C) | 50% | ||
| D) | 95% |
Approximately 50% of the dry weight of a typical human cell is protein [1]. Proteins assume numerous roles in the maintenance of homeostasis of the body as enzymes, contractile filaments of muscles, hormones, transporters, structural components, and a myriad of other substances. All proteins are composed of carbon, hydrogen, oxygen, and nitrogen. Additionally, some contain sulfur and/or phosphorus. Amino acids are composed of varying amounts of these basic elements and are the building blocks of all proteins. An adequate intake of protein is an essential component for optimal oral health at all stages of life.
| A) | Keratin | ||
| B) | Amylase | ||
| C) | Type I collagen | ||
| D) | Type X collagen |
The main types of collagen are I through V, each serving different functions. Type I collagen is the predominant protein in the structures of the oral cavity. The connective tissue in the gingiva is composed of type I and III collagen in a 5:1 ratio. Type III collagen predominates in granulation tissue that is the matrix for wound healing [3]. In the oral mucosa, type I and type III collagen are the main constituents of the upper connective tissues layer (lamina propria), while type I predominates in the deeper layers of the connective tissue stroma [4]. The amount of collagen in the layers of the tooth structure itself varies. Enamel is composed of 97% inorganic matrix; in the remaining 3% of organic matrix, type VII collagen has been identified surrounding the enamel rods at the dentin-enamel junction and may confer a higher resistance to fracture [5]. Type I collagen is the predominant protein in the dentin matrix and in the primary extracellular matrix of dental cementum [6]. Type I collagen is also the major collagenous constituent of the dental pulp, the periodontal ligament, and the alveolar bone. Small amounts of type III collagen are found in the dental pulp and the alveolar bone; about 20% of total collagen found in the periodontal ligament is type III [3].
| A) | disaccharide. | ||
| B) | bisaccharide. | ||
| C) | polysaccharide. | ||
| D) | monosaccharide. |
Carbohydrates are molecules that contain carbon, hydrogen, and oxygen, with the hydrogen and oxygen atoms in the same 2:1 ratio as water. Carbohydrates are classified according to size, with a monosaccharide being one sugar, a disaccharide being two sugars, and a polysaccharide being a polymer of simple sugars. The storage form of carbohydrates in plants is starch, but in animal tissues, it is glycogen stored mostly in the liver and skeletal muscles.
| A) | ketosis. | ||
| B) | anemia. | ||
| C) | xerostomia. | ||
| D) | weight gain. |
While no oral lesions are directly pathognomonic of decreased blood glucose levels (hypoglycemia), the oral mucosa requires consistent blood glucose levels to meet the metabolic demands of the rapidly dividing cells of its outer layer. The ability of erythrocytes to provide oxygen adequate for the metabolic needs of epithelial, muscle, nerve, and osseous cells can be compromised when glucose levels are decreased. Impaired erythrocyte function can also lead to anemia, which may manifest as pallor of the oral mucosa. Long-term restriction of carbohydrate intake can force the body to metabolize stored fat as an energy source (ketosis), with the potential to interrupt the acid-base balance of the body [9]. Because life-sustaining metabolic reactions occur in a limited pH range, a sustained state of nutritional ketosis can have an adverse multisystem effect.
| A) | Lipids have major implications for oral health. | ||
| B) | Lipids are water-soluble molecules composed of carbon, hydrogen, and oxygen. | ||
| C) | Patients who are on low-fat diets often develop impaired adrenocortical and gonadal hormone synthesis. | ||
| D) | Studies have suggested that low levels of omega-3 fatty acids may correlate with an increased risk of periodontitis. |
Lipids are water-insoluble molecules composed of carbon, hydrogen, and oxygen. Lipids include triglycerides, phospholipids, sterols, fats, and lipoproteins. The plasma membrane of all human cells is a lipid bilayer that is composed mostly of phospholipids, cholesterol, and glycolipids into which proteins are embedded [2]. The composition of the plasma membrane is critical, as it is the selectivity of this membrane that allows for the ingress of hormone and medication molecules that will exert a specific effect upon a specific tissue, organ, and/or system. Membrane permeability to ions such as sodium, calcium, and potassium is critical for the conduction of neural impulses and the contractility of cardiac and skeletal muscle fibers.
Adrenocortical and gonadal hormones require cholesterol for their synthesis. Many patients may be prescribed a diet low in cholesterol and saturated fat in order to decrease the risk of developing or worsening cardiovascular disease. In general, even these diets provide enough cholesterol and fat to support the body's functions.
As a class, lipids have minor implications for oral health. However, some animal studies have suggested that lipid molecules are a component of a protective layer on teeth that impedes the formation of a bacteria-laden biofilm. It is hypothesized that this layer may decrease the risk of smooth-surface caries [10]. Other studies have suggested that low levels of omega-3 fatty acids may correlate with an increased risk of periodontitis [10]. However, dental clinicians should not make recommendations to increase fat intake based on these limited studies given the prevailing evidence that implicates the various dietary lipids as risk factors in the development of cardiovascular disease.
| A) | Vitamin A | ||
| B) | Vitamin C | ||
| C) | Vitamin D | ||
| D) | Vitamin K |
Vitamins are organic compounds essential to at least one chemical reaction or process in the body. Vitamins also generally cannot be synthesized by the human body at all or are synthesized in quantities that are insufficient to meet the full needs of the body. Vitamins that can be stored in the body are considered fat-soluble, while those that cannot are considered water-soluble. Vitamins A, D, E, and K are fat-soluble vitamins, while the B-complex vitamins and vitamin C are water-soluble. Vitamins are not an energy source but are coenzymes or portions of coenzymes that enable chemical reactions to occur.
| A) | may result in hyperdontia. | ||
| B) | has been associated with anemia. | ||
| C) | has no known impact on oral development. | ||
| D) | can negatively impact the development of enamel and dentin. |
Vitamin A deficiency beginning in utero and continuing to the early teenage years can negatively impact the development of enamel and dentin. Calcification of the deciduous teeth occurs first on the maxillary and mandibular central incisors at about 14 weeks' gestation, while the initial calcification of the deciduous molars ranges from 15 to 23 weeks' gestation. The initial calcification of the permanent maxillary and mandibular first molars occurs about the time of birth, while those of the maxillary and mandibular third molars ("wisdom teeth") can range from 7 to 10 years [13]. As such, maternal vitamin A deficiency during pregnancy has the potential to adversely affect the formation of offsprings' enamel and dentin. Childhood deficiencies may likewise result in irregularities in permanent teeth; a vitamin A deficiency that develops in early adolescence or later would have minimal or no impact or oral health.
| A) | is water-soluble. | ||
| B) | cannot be stored in the skin or liver. | ||
| C) | has a significant impact on oral health. | ||
| D) | can be synthesized by the human body in reasonable quantities. |
Vitamin D is unique among the vitamins in that it can be synthesized by the human body in reasonable quantities provided that there is adequate access to sunlight and that the skin, liver, and kidneys are functioning. It also has characteristics of a hormone, as its physiologic activity requires interaction with a receptor [1]. In humans, the two most important forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).
| A) | Citrus fruits | ||
| B) | Vegetable oils | ||
| C) | Nuts and seeds | ||
| D) | Green leafy vegetables |
Vitamin E deficiency is rare, because it is widely distributed in foods, including vegetable oils, nuts, seeds, green leafy vegetables, and fortified breakfast cereals. However, muscular and neurologic problems can develop in patients with inadequate levels of vitamin E [11].
| A) | coagulation. | ||
| B) | bone formation. | ||
| C) | energy metabolism. | ||
| D) | proper functioning of the visual system. |
Vitamin K exists in three main forms. Phylloquinone occurs naturally in green plants; menaquinone is produced by bacteria in the intestine; and menadione is the synthetic version used in animal feed [21]. In humans, the most significant role of vitamin K is its role in coagulation. It serves as a catalyst for the synthesis of blood-clotting factors, especially in the maintenance of clotting factor II (prothrombin). The conversion of prothrombin to thrombin transforms the soluble clotting factor I (fibrinogen) to the insoluble polymer fibrin, which forms the cross-linked fibrin mesh at the foundation of a blood clot. Deficiencies in vitamin K are rare, given its availability in food and endogenous production by intestinal bacteria. However, deficiency can occur if intestinal absorption is impaired due chronic gastrointestinal disease and/or resection or long-term use of broad-spectrum antibiotics.
| A) | Erythematous oral mucosa | ||
| B) | Loss of the filiform and fungiform papilla of the tongue | ||
| C) | Gingival tissue changes that may resemble that of ulcerative gingivitis | ||
| D) | All of the above |
Oral manifestations of niacin deficiency can involve several structures. Loss of the filiform and fungiform papilla of the tongue changes its appearance to be smooth and shiny. The oral mucosa can become erythematous, and the gingival tissues may resemble that of ulcerative gingivitis [11]. Pain can emanate from any of the affected tissues and can interfere with the patient's ability to eat, speak, and swallow. The ability to maintain oral hygiene may also be compromised. Fortunately, niacin supplementation will reverse these effects. Liquid nutritional supplementation, topical and/or systemic analgesics, and a bland diet may be required until the oral tissues are restored to health. The pain associated with these manifestations usually precludes elective dental treatment. Patients who present with oral and/or systemic signs and symptoms should be referred to their physician for further evaluation.
| A) | Newborns | ||
| B) | Elderly individuals | ||
| C) | Women of childbearing age | ||
| D) | Strict vegetarians and particularly vegans |
Vitamin B12 serves as a coenzyme for fat and carbohydrate metabolism and protein synthesis and is integral component in the production of red blood cells. The absorption of vitamin B12 from the gastrointestinal tract requires that it binds to intrinsic factor, a substance produced by the parietal cells of the stomach mucosa. Vitamin B12 is absorbed in the distal small bowel (terminal ileum), and persons with disease of the terminal ileus (e.g., Crohn disease, Whipple disease, celiac disease) are at risk for malabsorption of vitamin B12 and other nutrients. The primary natural sources of dietary vitamin B12 are animal products, including fish and shellfish, beef, poultry, pork, eggs, and dairy products [2]. However, fortified cereals also usually contain 100% of the recommended daily value of vitamin B12. Strict vegetarians and particularly vegans (who consume no animal products) are at an increased risk of insufficient intake of vitamin B12, and these patients may benefit from vitamin B12-fortified foods, oral vitamin B12 supplements, or vitamin B12 injections [1].
| A) | 0.4 mg/liter. | ||
| B) | 1.4 mg/liter. | ||
| C) | 4.0 mg/liter. | ||
| D) | 14.0 mg/liter. |
There are levels at which chronic fluoride ingestion can be associated with adverse effects. The maximum allowable concentration of fluoride in community water systems, also known as the maximum contaminant level (MCL), is 4.0 mg/liter [43]. This level is nearly six times the recommended level for community water systems. As of 2023, the U.S. Environmental Protection Agency was in the process of reviewing the maximum amount of fluoride allowed in drinking water [41]. Ingestion of fluoride at the MCL for a long period of time can lead to the development of dental and skeletal fluorosis [44]. The most common adverse effect associated with the long-term ingestion of fluoride in excess of 2 mg/liter is dental fluorosis [45]. Mild forms of dental fluorosis feature small white spots or streaks in the dental enamel (i.e., mottled enamel). Severe forms of dental fluorosis feature brown or black pits in the enamel. These are not carious lesions but may require composite restorations, as surface pitting will enhance the retention of plaque and increase the potential for the development of caries. In more severe cases, all the enamel may be damaged [46]. A study published by the Centers for Disease Control and Prevention found that approximately 23% of the U.S. population between 6 and 49 years of age had some form of dental fluorosis; 16.0% had very mild fluorosis, 4.8% had mild fluorosis, 2.0% had moderate fluorosis, and less than 1% had severe fluorosis [47]. An additional 16.5% were classified as having questionable or possible dental fluorosis. This same study found that the rates of dental fluorosis among adolescents (12 to 15 years of age) significantly increased between 1986–1987 and 1999–2004. Skeletal fluorosis is characterized by pain and stiffness in major joints and an increased risk for fractures. This condition is rare in the United States [46].
| A) | Zinc | ||
| B) | Calcium | ||
| C) | Fluoride | ||
| D) | Phosphorus |
Calcium is the most abundant mineral in the human body and accounts for about 40% of its mineral composition; approximately 99% of this calcium is sequestered in the bones and teeth [1]. Calcium plays a role in the formation of teeth and bone, muscle contraction, coagulation, cardiac rhythm maintenance, and enzyme reactions.
| A) | dietary sources. | ||
| B) | occupational exposures. | ||
| C) | community water sources. | ||
| D) | denture adhesive pastes, powders, or pads. |
Concern about zinc levels has generally focused on systemic complications from excessive ingestion rather than a deficiency. Aside from nutritional supplements, the most common source of excess zinc is denture adhesive pastes, powders, or pads. Many patients who use partial or complete dentures use an adhesive to provide additional retention for eating and speaking. While properly fabricated prostheses should require no or little adhesive, over time the mucosa and underlying bone atrophy, which can compromise retention and function. Ideally, the existing prostheses should be relined or replaced to reflect the patient's current oral topography. However, the cost can be prohibitive for some, leading to a reliance on adhesive. The cumulative ingestion of zinc from denture adhesives and dietary sources can result in a systemic excess, with the competitive inhibition of copper absorption the primary concern. Zinc and copper use similar metabolic pathways for absorption from the gastrointestinal tract. Therefore, an increase in zinc in the digestive tract will decrease the amount of copper absorbed; when this is sustained, a copper deficiency (hypocupremia) can develop [53]. Symptoms of hypocupremia develop gradually and can include anemia, gait and balance problems, and paresthesias in the extremities [54]. Patients with excessive zinc are often older and may attribute these issues to conditions common with aging. It is therefore essential for dental professionals to educate their patients about the potential systemic complications of sustained ingestion of zinc-containing denture adhesives. Zinc-free denture adhesives have been developed and are the preferred formulations, when possible.
| A) | Phosphorus deficiencies are common. | ||
| B) | Certain gastrointestinal conditions can compromise a patient's ability to absorb phosphorus. | ||
| C) | Conditions such as diabetes, malnutrition/ anorexia, and alcohol use disorder can increase phosphorus levels in the body. | ||
| D) | All of the above |
Deficiencies of phosphorus are rare, as this mineral found in many foods, including dairy products, meats and poultry, fish, eggs, nuts, legumes, vegetables, and grains. However, conditions such as diabetes, malnutrition/anorexia, and alcohol use disorder can decrease phosphorus levels in the body. Certain gastrointestinal conditions, such as Crohn disease and celiac disease, can compromise a patient's ability to absorb phosphorus and other nutrients. Symptoms of a phosphorus deficiency are not pathognomonic but include anxiety, fragile bones, fatigue, irregular breathing, numbness, and weight change [55]. Referral to a physician is advisable when phosphorus deficiency is suspected.
| A) | Chemotherapy | ||
| B) | Radiation therapy | ||
| C) | Weight loss and increased physical activity | ||
| D) | Strict, lifelong gluten-free diet and supportive nutritional care |
A strict, lifelong gluten-free diet and supportive nutritional care (for iron, calcium, and vitamin deficiencies) is the only recommended treatment for celiac disease [61,66,67,68,69]. Adherence to a gluten-free dietary pattern involves all foods containing or derived from wheat, barley, and rye. This may result in a diet that is low in carbohydrates, iron, folate, niacin, zinc, and fiber. Individuals with celiac disease often suffer from malabsorption and can develop vitamin and mineral deficiencies despite adequate intake. Age-specific gluten-free vitamin and mineral supplements are an important addition to the diets of persons with celiac disease [70]. Iron supplements are recommended for iron-deficiency anemia, and folic acid and vitamin B12 should be taken to avoid anemia due to folate or B12 deficiencies. Vitamin K is necessary for individuals with abnormal prothrombin times. Calcium and vitamin D supplements should be encouraged for individuals with low blood calcium levels or osteoporosis.
| A) | Xerostomia | ||
| B) | Aphthous stomatitis | ||
| C) | "Cobblestoning" of the buccal mucosa | ||
| D) | Inflammation of the salivary glands and ducts |
The initial signs of Crohn disease can include specific and nonspecific oral manifestations. Oral changes that are considered specific and pathognomonic of Crohn disease include mucosal tags (similar to skin tags), "cobblestoning" of the buccal mucosa, deep linear ulcerations, and oral granulomatosis (mainly affecting the lips). Nonspecific changes can include xerostomia, aphthous stomatitis, mucogingivitis, and inflammation of the salivary glands and ducts [21].
| A) | Nutrient deficiencies | ||
| B) | Chronic regurgitation | ||
| C) | Gastroesophageal reflux disease | ||
| D) | All of the above |
The oral side effects of bariatric surgery vary among patients. As with all patients, oral hygiene habits and adherence to routine dental prophylaxis appointments should be stressed. Aside from nutritional deficiencies, patients may develop gastroesophageal reflux disease (GERD) and chronic vomiting.
| A) | is not seen in patients with bulimia nervosa. | ||
| B) | develops from repetitive tooth-to-tooth contact. | ||
| C) | is caused by an abrasive force, such as overzealous tooth brushing. | ||
| D) | is caused by repeated contact of gastric hydrochloric acid with the teeth. |
Enamel is the hardest substance in the human body, but the repeated exposure to the hydrochloric acid in regurgitated gastric contents over an extended period of time can lead to a unique pattern of enamel erosion called perimylolysis. Perimylolysis features the loss of enamel on the lingual, occlusal, and incisal surfaces of the teeth. As opposed to attrition, which is the loss of enamel from repetitive tooth-to-tooth contact or abrasion via an external source (e.g., excessive or overly forceful tooth brushing), the gradual dissolution of the enamel matrix in patients with bulimia nervosa leaves a glossy, smooth surface, most commonly on the lingual surfaces of the maxillary anterior teeth [95]. Any lost enamel cannot be regenerated. The underlying matrix of dentin is then exposed; it will wear faster than enamel and is more prone to caries. While enamel is devoid of any neural element, dentin contains dentinal tubules whose odontoblastic processes can perceive thermal stimuli as a source of pain. This can cause patients to neglect oral hygiene and increase the risk of caries and periodontal disease. The irreversible loss of enamel will also cause a change in the occlusion, decreasing the vertical dimension of occlusion. The loss of tooth structure requires that more complicated and expensive restorative options, such as crowns, be utilized. The loss of enamel support around composite or amalgam restorations can lead to their weakening and ultimate loss. The amount of time necessary for the enamel to be eroded in such fashion can range from six months to two years [96].