1 . Which of the following statements describes type A adverse drug effects?
| A) | | They are always minor. |
| B) | | They include allergic reactions. |
| C) | | They are less common than type B adverse drug effects. |
| D) | | They are known pharmacologic effects of a medication. |
Adverse drug effects can be categorized as either type A or
type B [2]. The most frequent adverse drug
reactions (type A) are known pharmacologic effects of a medication. For example, many
medications provide warnings about nausea or drowsiness as a potential adverse effect.
Although type A reactions are known possibilities, they can be very serious, even
life-threatening. In some cases, type A reactions may be incorrectly identified as
"allergies," particularly by patients.
2 . Anaphylaxis is an example of which category of hypersensitivity reactions?
| A) | | Type I |
| B) | | Type II |
| C) | | Type III |
| D) | | Type IV |
PATHOPHYSIOLOGY AND CATEGORIZATION OF ALLERGIC REACTIONS
Type I allergic reactions are immediate, with an onset of
only a few minutes to a few hours. The most serious type I hypersensitivity reaction is
anaphylaxis, the most serious degree of an allergic response. It is characterized by a set
of symptoms that involves various organs and systems and occurs independently,
simultaneously, or subsequently [6]. Initial
symptoms often include widespread hives and progress rapidly to bronchospasm, respiratory
arrest, and ultimately, cardiac arrest. Whether the anaphylactic reaction is of immune or
nonimmune origin, the stimulation of mast cells and circulating basophils releases chemical
mediators that begin the anaphylactic process. A rapidly escalating systemic reaction can
occur only minutes after exposure to a specific antigen or onset may be delayed several
hours [7]. In 1% to 20% of anaphylaxis
cases, there will be a biphasic response, with recurrence of symptoms 8 to 12 hours later,
after the individual had seemed to recover [8]. The interval between the initial reaction and the recurrence has ranged from 1 to 72
hours [9,10].
3 . All of the following are among the most common triggers of contact dermatitis, EXCEPT:
| A) | | Fruits |
| B) | | Metals |
| C) | | Medications |
| D) | | Rubber products |
PATHOPHYSIOLOGY AND CATEGORIZATION OF ALLERGIC REACTIONS
The most common triggers of contact dermatitis are rubber
products, metals, and medications that are applied directly to mucosal or cutaneous
tissues. There are two main forms: irritant contact dermatitis and allergic contact
dermatitis.
4 . Most allergic reactions to local anesthetics occur in response to
| A) | | injected anesthetics. |
| B) | | ester-type anesthetics. |
| C) | | amide-type anesthetics. |
| D) | | All of the above |
ALLERGIES TO MEDICATIONS USED IN DENTISTRY
Local and topical anesthetics are chemically classified as
either amides or esters. The most frequently used injectable local anesthetics today,
including lidocaine, mepivacaine, and bupivacaine, are all amides. Articaine is also
classified as an amide but has the unique feature of the inclusion of an ester group.
Allergies to amide local anesthetics have been very rare; most allergic reactions occur in
response to ester types. Ester-type local anesthetics are metabolized to para-aminobenzoic
acid, which has allergenic properties [21].
While the ester anesthetic procaine is no longer used in North America, benzocaine is a
widely used ester topical anesthetic applied to the oral mucosa prior to the injection of a
local anesthetic. An allergic reaction to benzocaine is usually limited to the site of its
application and can manifest as an area of erythema or ulceration.
5 . What percentage of the U.S. population has an allergy to penicillin?
ALLERGIES TO MEDICATIONS USED IN DENTISTRY
Approximately 10% of the U.S. population has a reported
allergy to penicillin, but only about 1% of the population has a true IgE-mediated
allergic reaction [23,51]. While most allergic reactions to
penicillin and its derivatives result in skin rashes or urticarial lesions, medications in
this group are among the most frequent causes of medication-induced anaphylaxis [24]. Type I reactions can progress to
anaphylaxis in 0.04% to 0.2% of cases, with a 10% fatality rate [1]. Fortunately, most allergic reactions to
penicillin are less severe but can still cause varying degrees of discomfort or
morbidity.
6 . Type IV (delayed) hypersensitivity reactions to NSAIDs may manifest as
| A) | | erythema multiforme. |
| B) | | maculopapular lesions. |
| C) | | Stevens-Johnson syndrome. |
| D) | | All of the above |
ALLERGIES TO MEDICATIONS USED IN DENTISTRY
In dentistry, the frequency of hypersensitivity reactions
among NSAIDs is second only to those caused by beta-lactam antibiotics [31]. IgE-mediated reactions are rare, but
when they do occur, they tend to develop soon after ingestion of either ibuprofen or
naproxen and can feature urticaria, angioedema, respiratory distress, and anaphylaxis.
Type IV (delayed) hypersensitivity reactions may also occur; manifestations can include
cutaneous reactions such as maculopapular lesions, erythema multiforme, and
Stevens-Johnson syndrome, any of which can take 24 to 72 hours to develop.
Cross-reactivity among all NSAIDs is possible but infrequent, as the molecular structures
of this group of medications can vary considerably [32]. However, if a patient indicates he or she has had an allergic
reaction to ibuprofen, naproxen, or any other NSAID, it would be prudent to consult with
the patient's physician before prescribing or administering any medication in this group.
A hypersensitivity reaction to ibuprofen contraindicates its use when combined with other
medications, such as hydrocodone. Patients who have had allergic reactions to ibuprofen or
naproxen should also be advised to exercise caution when selecting over-the-counter
analgesics.
7 . All of the following are "red flags" for the possible development of a latex allergy, EXCEPT:
| A) | | No prior exposure to latex products |
| B) | | History of irritant or allergic contact dermatitis |
| C) | | Allergy to certain fruits (e.g., banana, avocado) |
| D) | | History of having undergone multiple surgeries for any reason, particularly beginning in childhood |
ALLERGIC REACTIONS TO MATERIALS USED IN DENTISTRY
A type I hypersensitivity reaction to natural rubber latex
can occur without any prior hypersensitivity reaction, but there are certain indicators in a
patient's medical history that should raise a "red flag" for a potential allergy. Patients
with a history of irritant or allergic contact dermatitis can develop a progressive
sensitization to natural rubber latex components. Subsequent exposure to any latex product
can precipitate a hypersensitivity reaction in these individuals. Patients who have
undergone multiple surgeries for any reason, particularly beginning in childhood, have
likely been repeatedly exposed to natural rubber latex and can develop a progressive
sensitization. Also, as discussed, persons with an allergy to certain fruits (e.g., banana,
avocado) are at an increased risk for latex hypersensitivity. The basis of this
cross-reactivity is the structural similarity between the protein-composed enzymes that the
rubber tree uses to defend itself against microbial colonization, particularly fungal
organisms, and the protein-based enzymes that perform the similar antimicrobial function in
these fruit trees/vines [40].
8 . The most common hypersensitivity reaction to dental amalgam in the oral soft tissue is
| A) | | urticaria. |
| B) | | Kaposi sarcoma. |
| C) | | oral lichen planus. |
| D) | | oral lichenoid lesions. |
ALLERGIC REACTIONS TO MATERIALS USED IN DENTISTRY
In the oral soft tissue, the most common hypersensitivity
reaction to dental amalgam is a type IV response known as oral lichenoid lesions. These
erythematous lesions develop on the oral mucosa in direct contact with an offending
material (e.g., dental amalgam, epoxy resins, composite restorations, orthodontic
appliances) [43]. It is a T-cell mediated
response that develops over time as mercury salts or other ions penetrate through the
epithelial lining and incorporate into the surface proteins of the basal keratinocytes
[44].
9 . Which of the following statements regarding nickel allergy is TRUE?
| A) | | Nickel allergy is more common in men than women. |
| B) | | Nickel is rarely associated with any type of allergic reaction. |
| C) | | The usual manifestation is a delayed type IV reaction (specifically, allergic contact dermatitis). |
| D) | | When present in an alloy (i.e., mixed with other metals), nickel is incapable of triggering an allergic reaction. |
ALLERGIC REACTIONS TO MATERIALS USED IN DENTISTRY
Despite its widespread use, the American Contact Dermatitis
Society named nickel the contact allergen of the year in 2008, and it is a common cause of
allergic contact dermatitis [45]. Nickel
allergy is much more common in women (10%) than men (1% to 2%), likely due to
sensitization from nickel-containing jewelry [46]. It is extremely rare for a nickel-containing crown or cast-metal
partial denture framework to cause an immediate type I hypersensitivity reaction; the
usual manifestation is a delayed type IV reaction (specifically, allergic contact
dermatitis).
10 . The medication of choice to treat anaphylaxis is
| A) | | lidocaine. |
| B) | | penicillin. |
| C) | | epinephrine. |
| D) | | corticosteroids. |
TREATMENT OF HYPERSENSITIVITY REACTIONS IN DENTAL PATIENTS
Epinephrine remains the medication of choice to treat
anaphylactic shock. Commercially prepared pre-loaded syringes of 0.3 mg of 1:1,000 epinephrine
(usually referred to by their brand name, EpiPen) can be injected into the deltoid or vastus
lateralis muscles or in the sublingual region. The highly vascular sublingual region can
promote rapid absorption of the drug. Subcutaneous administration does not provide as much
bioavailability of epinephrine as the intramuscular or sublingual routes [50].
