Question 1

Angle's classification is a limited assessment of occlusion in which of the following ways?

Accepted Answer

All of the above describe the limitations of Angle's classification of occlusion. A thorough evaluation of the client's occlusion should include assessments of the teeth in the transverse plane of space to identify the presence of crossbite malrelationships, as well as assessments of the teeth in the vertical plane of space, to identify the presence of deep overbite or open bite malrelationships. In addition, the impact of the skeletal relationships of the maxilla and mandible in any malocclusion must be determined.

Question 2

Orthodontic forces applied to a tooth must be light and maintained in order to do which of the following?

Accepted Answer

Orthodontic forces applied to a tooth must be light and maintained in order to produce frontal resorption on the pressure side of the tooth, enabling optimal tooth movement. During the process of frontal resorption, light pressure is applied to stimulate osteoclastic activity in the PDL space. Hyalinization occurs when the pressure applied is too heavy, producing a necrotic PDL space that is devoid of all cells. Tooth movement is then delayed for 7 to 14 days until osteoclasts and osteoblasts from the adjacent regions can produce the required bone remodeling. This type of resorption that is produced by heavy pressure results in delayed tooth movement that is called undermining resorption. Optimal orthodontic tooth movement is produced by forces that are light and maintained rather than heavy. Heavy forces produce necrotic PDL spaces that result in delayed tooth movement.

Question 3

The pubertal growth spurt is important to consider when orthodontic treatment is planned. The pubertal growth spurt begins at an earlier age in _____ and lasts for a _____ period of time than in _____.

Accepted Answer

The pubertal growth spurt is correctly described in choice D. It begins at an earlier age in girls and lasts for a shorter period of time than in boys.

Question 4

A skeletal malocclusion is treated by which of the following?

Accepted Answer

Orthodontic treatment of a skeletal malocclusion may include any of the three therapies listed, depending on the age of the client, and the type and severity of the malocclusion. Skeletal malocclusions that are not fully corrected may be camouflaged by tooth movement to minimize the discrepancy. Growth modification may be initiated at an early age to either restrict or enhance the growth of a jaw to prevent the development of discrepancies between the jaws. In some cases, however, surgical therapy will be needed to correct skeletal malrelationships.

Question 5

Based on the equilibrium theory, the position of the teeth is determined by forces applied by which of the following?

Accepted Answer

Based on the equilibrium theory, the position of the teeth is determined by forces applied by all of the above soft tissues. Although the forces applied by the lips, cheeks, tongue, and periodontal ligament are light in magnitude, they are applied for a long period of time throughout the day. Tooth position remains stable as long as the magnitude of the forces applied by these tissues exists in a state of equilibrium.

Question 6

The age of eruption is more important than the sequence of eruption of the permanent teeth.

Accepted Answer

There is great variation in the age at which the teeth will erupt in individual clients. The sequence in which the teeth develop is a more important indicator of normal development of the dentition than is the age of the client.

Question 7

Two types of spacing that are desirable in the primary dentition are:

Accepted Answer

Primate and developmental spacing are two types of spacing that are desirable in the primary dentition. Spacing is desirable in the primary dentition stage, because it provides the room needed for the eruption of the permanent teeth, which are larger in size mesiodistally.

Question 8

An adult client in orthodontic treatment is taking nifedipine, a calcium channel blocking agent, to control hypertension. What is the concern for this client?

Accepted Answer

The concern for the adult client who is taking nifedipine while undergoing orthodontic therapy is the potential for the development of enlarged, hyperplastic gingival tissues in the presence of increased plaque biofilm accumulation around brackets and bands. Nifedipine is a calcium channel blocking antihypertensive agent and is not related to hormonal imbalance, increased bone density, or prostaglandin inhibition.

Question 9

A dental hygienist can play a large role in evaluating and documenting the oral health status of a client at the initiation of the orthodontic evaluation. Which of the following may be completed by the dental hygienist?

Accepted Answer

A dental hygienist can play a large role in evaluating and documenting the oral health status of a client at the initiation of the orthodontic evaluation by the completion of all listed diagnostic procedures. The dental hygienist may complete the periodontal assessment, expose required radiographs, and expose all intraoral and extraoral photographs required to document the client's status at the initiation of treatment.

Question 10

During orthodontic treatment, it is possible that fragments of cementum and dentin will break away from the apex of the root and then become absorbed by the body. This results in which of the following?

Accepted Answer

Blunting of the apex with shortening of the root length can occur during orthodontic treatment. Fragments of cementum and dentin that break away from the apical region of the root will not be redeposited and will eventually be absorbed by the body. This process does not produce a thin, sharply pointed root apex, nor does it contribute to the development of endodontic infection. Because the lost structure is not redeposited at the root apex, lengthening of the root will not occur.

Question 11

Two principles important to growth modification therapy are which of the following?

Accepted Answer

Two principles important to growth modification therapy are growth modification must be carried out in clients who are actively growing, and it must continue until skeletal growth is complete. To alter the growth of the jaws, it is best if treatment is conducted in the mixed dentition stage before or during the adolescent growth spurt. Therefore pressure can be applied to guide the jaws into the most optimal positions possible. Orthodontic management of skeletal growth must then continue until the facial structures have completed growth, because these structures can be expected to continue to express the tendency to produce the same skeletal malrelationships throughout the development of the skeletal facial structures that were originally noted in the child. The child need not be of a very young age and the need for optimal plaque control is no more important during growth modification than during traditional fixed orthodontic treatment involving tooth movement alone.

Question 12

Serial extraction and palatal expansion therapies are completed to:

Accepted Answer

Serial extraction and palatal expansion therapies are completed to treat severe crowding problems. Expansion of the palate creates more arch space; therefore it is not indicated to achieve closure of maxillary anterior diastemas. In addition, these procedures are not used to maintain the space of a primary tooth that is lost prematurely.

Question 13

A malocclusion may occur in any of three planes of space. A posterior crossbite is a malocclusion occurring in which of the following?

Accepted Answer

A posterior crossbite is a malocclusion occurring in the transverse plane of space. A malocclusion in the vertical plane of space manifests as either an open bite or a deep overbite. A malocclusion in the anteroposterior plane of space manifests as either a Class II or a Class III malocclusion.

Question 14

A prolonged (more than 6 hours per day) thumbsucking habit may cause the development of which of the following?

Accepted Answer

A prolonged (more than 6 hours per day) thumbsucking habit may cause the development of all of the above conditions. The placement of the thumb between the maxillary and mandibular teeth for an extended time will inhibit the eruption of the incisors and produce a protrusion of the incisor teeth. Because the posterior teeth will remain out of occlusion while the thumb is sucked, overeruption of the posterior teeth can occur as well. Prolonged sucking of the thumb produces tension of the buccal musculature, which can cause lingual displacement of the maxillary posterior teeth. This constriction of the maxillary arch can result in a posterior crossbite.

Question 15

The most ideal relationship of the second molars in a primary dentition is which of the following?

Accepted Answer

The most ideal relationship of the second molars in a primary dentition is the mesial step relationship. The permanent dentition should develop into a Class I occlusion. The distal step relationship, at best, will develop into an end-to-end molar relationship in the permanent dentition. The distal step relationship may also develop into a Class II relationship in the permanent dentition. There is no relationship called the "proximal terminal plane relationship." The flush terminal plane relationship may develop into a Class I molar relationship after mesial shifting of the molars into primate and/or leeway spaces.

Question 16

If a client experiences significant pain after orthodontic appointments, when is it best to schedule supportive periodontal therapy appointments?

Accepted Answer

When a client experiences significant pain after orthodontic appointments, it is best to schedule supportive periodontal therapy appointments before the orthodontic adjustment appointments. Immediately after orthodontic adjustment appointments is not the best time for these clients because painful sensations may develop within hours of the adjustment and last for several days. An 8-month recall interval is too long an interval for most orthodontic clients. Although an over-the-counter analgesic will relieve pain associated with orthodontic movement, the best time to schedule supportive periodontal therapy appointments is before these adjustments.

Question 17

Because the duration of a force is more important than the magnitude (strength) of the force applied, habits such as thumbsucking will not produce tooth movement unless practiced for at least how many hours per day?

Accepted Answer

Because the duration of a force is more important than the magnitude (strength) of the force applied, habits such as thumbsucking will not produce tooth movement unless practiced for at least 6 hours per day.

Question 18

The permanent teeth continue to erupt in adolescents even after they have reached the plane of occlusion. This occurs for which of the following reasons?

Accepted Answer

In adolescents the permanent teeth continue to erupt even after they have reached the plane of occlusion because the ramus continues to grow in the vertical dimension until the late teen years. Eating habits of adolescents have no impact on the continued eruption of the teeth. Tooth eruption is not directly a part of the pubertal growth spurt. Rather, it is a response to the increased vertical height of the ramus. The maxilla develops during adolescence in such a manner that the maxillary teeth are translated downward and forward. This pattern of development will not contribute to the continued eruption of the teeth.

Question 19

Mild crowding of the permanent mandibular incisors may resolve after the age of 10 for which of the following reasons?

Accepted Answer

Mild crowding of the permanent mandibular incisors may resolve after the age of 10 because the presence of primate space distal to the mandibular canines allows space for the mandibular canines to move distally, creating more room for the mandibular incisors and alleviating mild crowding problems. The permanent mandibular incisors are significantly larger in size than the primary mandibular incisors. The mandibular incisors erupt in a labial, as well as an incisal direction, which increases the arch space. Although consistent, low-grade forces of the tongue while at rest contribute to tooth movement, this alone will not necessarily create adequate room to resolve crowding.

Question 20

Pain during orthodontic tooth movement is the result of which of the following?

Accepted Answer

Pain during orthodontic tooth movement is the result of ischemic necrosis of the PDL. Frontal resorption is a component of ideal orthodontic tooth movement and refers to the process in which osteoclasts remove bone on the pressure side of the tooth to allow movement of the tooth into the desired position. Undermining resorption also refers to bone remodeling by osteoclasts. In this case, however, osteoclasts and osteoblasts are supplied by adjacent areas of the PDL that have not been necrosed as a result of excessive orthodontic force. Normal orthodontic forces can produce mild pulpitis in the teeth; however, this effect is reversible. Damage to the pulp of the teeth is not a typical result of normal orthodontic forces.

Quiz 59: Persons With Orthodontic Appliances