Orthodontics: Skeletal and Dental Malocclusion

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Questions and Answers

What is Classification?

morphologic description of dental, skeletal, and soft tissue deviations from the norm

Morphologic deviations from the norm are used to arrive at a _ that leads to ________.

diagnosis; 2. develop the treatment objectives and treatment plan

What is Angle's postulate?

upper 1st molars are the key to the occlusion

What is normal occlusion in Angle's classification?

<ol> <li>MB cusp of upper 1st molar occludes in the buccal groove of the lower 1st molar; 2. all teeth are arranged on a smoothly curving line of occlusion</li> </ol> Signup and view all the answers

What is line of occlusion?

<ol> <li>a smooth curve passing through the Central fossa of each Upper Molar and across the Cingulum of the upper Canines and Incisors; 2. same line runs along the buccal cusps and incisal edges of the lower teeth</li> </ol> Signup and view all the answers

What are the 4 classes of Angle's Classification?

<ol> <li>normal occlusion; 2. class I malocclusion; 3. class II malocclusion; 4. class III malocclusion</li> </ol> Signup and view all the answers

What is Angle's Class I malocclusion?

normal relationship of molars, but the line of occlusion is incorrect because of maloposed teeth, rotations, or other causes Signup and view all the answers

What is Angle's Class II malocclusion?

lower molar distally positioned relative to upper molar Signup and view all the answers

What are 4 features of Angle's Class II division I?

<ol> <li>proclined upper incisors; 2. narrow maxilla; 3. deep bite, normal bite, open bite; 4. incompetent lips</li> </ol> Signup and view all the answers

What are 5 features of Angle's Class II division II?

<ol> <li>retroclined upper central incisors; 2. proclined or retroclined upper laterals; 3. deep bite; 4. deep curve of spee in the lower arch; 5. competent lips - close lips at rest without showing muscle strain</li> </ol> Signup and view all the answers

What is an example of subdivisions?

class II occlusion on one side and Class I on the other Signup and view all the answers

What is Angle's Class III malocclusion?

lower 1st molar mesially positioned relative to upper 1st molar Signup and view all the answers

What are 3 criticisms of the Angle Classification?

<ol> <li>Angle assumed the upper first molar was always in the correct location; 2. no skeletal consideration; 3. it only describes an anterior-posterior relationship</li> </ol> Signup and view all the answers

What is the most common Angle's malocclusion?

Class I Signup and view all the answers

What is the research use of Radiographic Cephalometrics?

observe growth patterns in the craniofacial complex Signup and view all the answers

What is the diagnostic use of Radiographic Cephalometrics?

<ol> <li>characterize the patient's dental and skeletal relationships</li> </ol> Signup and view all the answers

What is the evaluation use of Radiographic Cephalometrics?

measure the change in tooth and jaw position produced by growth treatment Signup and view all the answers

What is the skeletal pattern in Class I skeletal malocclusion?

well proportioned jaws (only dental malocclusion) Signup and view all the answers

What is the skeletal pattern in Class II skeletal malocclusion?

mandible is retrusive relative to the maxilla (skeletal and/or dental malocclusion) Signup and view all the answers

What is the skeletal pattern in Class III skeletal malocclusion?

mandible is protrusive relative to maxilla (skeletal and/or dental malocclusion) Signup and view all the answers

What is Brachyfacial type?

broad square face with a strong chin, flat mandibular plane, a straight profile Signup and view all the answers

What is Dolicofacial Type?

a long, narrow face with a steep mandibular plane, convex profile, recessive chin, an anterior-posterior face height imbalance Signup and view all the answers

What is Mesofacial type?

between brachyfacial and dolicofacial types, an average face in well-balanced proportion Signup and view all the answers

What is a retrognathic chin?

pulled back Signup and view all the answers

What is a prognathic chin?

pushed forward Signup and view all the answers

When is growth of width completed?

before adolescent growth spurt Signup and view all the answers

When is growth of length completed?

through the period of puberty Signup and view all the answers

When is growth of height completed?

longer than growth in length Signup and view all the answers

What are 3 factors that affect crossbite?

<ol> <li>genetics - skeletal constriction; 2. habits; 3. environmental - dental interference</li> </ol> Signup and view all the answers

What are genetic factors that cause crossbite?

<ol> <li>asymmetric growth of the maxilla or the mandible; 2. discrepancy of basal bone width</li> </ol> Signup and view all the answers

What are 7 environmental things that can cause crossbite?

<ol> <li>premature loss or prolonged retention of primary teeth; 2. crowding; 3. abnormal eruption sequence; 4. impaired nasal breathing during growth; 5. pathology; 6. trauma; 7. iatrogenic injury</li> </ol> Signup and view all the answers

What are 4 habits that cause crossbite?

<ol> <li>tongue thrusting; 2. mouth breathing; 3. non-nutritive sucking; 4. jaw posture habits</li> </ol> Signup and view all the answers

What are 3 factors of habits that are important in causing crossbite?

<ol> <li>frequency; 2. intensity; 3. duration of the habits - more than 6 hours per day</li> </ol> Signup and view all the answers

What are 7 characteristics of mouth breathing?

<ol> <li>increased facial height; 2. super-eruption of posterior teeth; 3. downward and backward rotation of mandible; 4. opening bite anteriorly; 5. labioversion of maxillary anterior teeth; 6. increased overjet; 7. contraction of maxillary arch</li> </ol> Signup and view all the answers

What are 4 characteristics of thumb-sucking?

<ol> <li>thumb sucking against maxilla promotes development of Class II malocclusion; 2. maxillary incisors are pushed labially; 3. mandibular incisors are pushed lingually; 4. buccal muscles exert pressure lingually against posterior teeth</li> </ol> Signup and view all the answers

What are 2 causes of dental crossbite?

<ol> <li>displacement of teeth; 2. occlusal shifting</li> </ol> Signup and view all the answers

What is the primary cause of skeletal crossbite?

maxillary constriction Signup and view all the answers

What malocclusion is anterior crossbite/jaw discrepancy related to?

class III Signup and view all the answers

What malocclusion is posterior crossbite related to?

Classes I, II, or III Signup and view all the answers

How to tell the difference between skeletal and dental crossbite?

<ol> <li>dental crossbite; lingual shift of maxillary teeth; 2. skeletal; buccal shift</li> </ol> Signup and view all the answers

What does untreated posterior crossbite result in?

<ol> <li>wear facets on posterior teeth; 2. wrapping of the alveolar ridges; 3. asymmetry of the arch and/or face; 4. possible periodontal problem</li> </ol> Signup and view all the answers

Is bilateral or unilateral crossbite more common?

True Signup and view all the answers

Is there functional shift in unilateral crossbite?

False Signup and view all the answers

What are 3 causes of true unilateral crossbite?

<ol> <li>alveolar deformation; 2. maxillary asymmetry; 3. mandibular asymmetry</li> </ol> Signup and view all the answers

Functional shift can be masking a _____ crossbite.

bilateral Signup and view all the answers

What happens to compensate for bilateral crossbite?

mandible shifts in order to achieve max occlusion, causing unilateral expression of bilateral crossbite Signup and view all the answers

Why should anterior/posterior crossbites be treated as soon as possible?

because the position of primary teeth can influence the developing permanent tooth buds Signup and view all the answers

What is the sagittal plane used to evaluate?

<ol> <li>relationship between maxilla/mandible and the cranial base; 2. relationship between the maxilla and the mandible; 3. overjet; 4. anterior crossbite; 5. molar and canine occlusal relationship</li> </ol> Signup and view all the answers

What are 4 causes of Dental (upper arch) Class II malocclusion?

<ol> <li>early loss of primary molars; 2. dental agenesis; 3. M/D cavities with loss of interproximal tooth mass; 4. molar rotation (mesially rotated)</li> </ol> Signup and view all the answers

What are 3 causes of Skeletal Class II malocclusion?

<ol> <li>maxillary protrusion; 2. mandibular retrusion; 3. combination</li> </ol> Signup and view all the answers

What are 5 characteristics of Class III occlusion?

<ol> <li>proclined upper incisors; 2. retroclined lower incisors; 3. anterior/posterior crossbite; 4. midface deficiency; 5. concave profile</li> </ol> Signup and view all the answers

What are 3 causes of Dental (lower arch) Class III malocclusion?

<ol> <li>early loss of primary molars; 2. dental agenesis; 3. M/D cavities with loss of interproximal tooth mass</li> </ol> Signup and view all the answers

What are 3 causes of Skeletal Class III malocclusion?

<ol> <li>maxillary retrusion; 2. mandibular prognatism; 3. combination (most common)</li> </ol> Signup and view all the answers

What is evaluated in the transverse plane?

<ol> <li>midline deviation; 2. crossbite</li> </ol> Signup and view all the answers

What is evaluated in the vertical plane?

<ol> <li>facial pattern; 2. open bite; 3. deep bite</li> </ol> Signup and view all the answers

What is anterior open bite? What are 2 causes?

<ol> <li>failure of incisor teeth to overlap; 2. habit/post teeth erupt excessively</li> </ol> Signup and view all the answers

What is posterior open bite? What are 3 causes?

<ol> <li>failure of posterior teeth to occlude, unilaterally or bilaterally; 2. habits; 3. failure of posterior eruption/ankylosis</li> </ol> Signup and view all the answers

What is anterior deep bite? What are 2 causes?

<ol> <li>upper incisors overlap lower incisors excessively; 2. deep curve of spee/lack of anterior contact</li> </ol> Signup and view all the answers

What is the primary dentition tooth ID system in ortho? What is it for permanent dentition?

<ol> <li>EDCBA ABCDE; 2. 87654321 12345678</li> </ol> Signup and view all the answers

Study Notes

Classification of Malocclusion

Classification refers to the morphologic description of deviations in dental, skeletal, and soft tissue from the norm.
Morphologic deviations inform diagnosis, treatment objectives, and treatment planning.

Angle's Classification

Angle's postulate highlights the upper 1st molars as the key to occlusion.
Normal occlusion is characterized by the MB cusp of the upper 1st molar occluding in the buccal groove of the lower 1st molar, with all teeth arranged along a smoothly curving line.

Types of Angle's Malocclusion

Four classes in Angle's classification:
- Normal occlusion
- Class I malocclusion: Molar relationship is normal but line of occlusion is incorrect due to dental factors.
- Class II malocclusion: Lower molars are positioned distally to upper molars.
- Class III malocclusion: Lower 1st molar is mesially positioned relative to the upper 1st molar.

Class II Malocclusion Variants

Class II Division I features include proclined upper incisors, narrow maxilla, deep bite, and incompetent lips.
Class II Division II features include retroclined upper central incisors, deep bite, and competent lips.

Subdivisions and Classifications

Subdivisions involve Class II occlusion on one side and Class I on the other side.
Class I malocclusion is the most common Angle's classification.

Radiographic Cephalometrics

Research use assesses growth patterns in the craniofacial complex.
Diagnostic use helps characterize dental and skeletal relationships.
Evaluation use measures changes in tooth and jaw position due to treatment.

Skeletal Malocclusion Patterns

Class I skeletal malocclusion features well proportioned jaws with dental malocclusion.
Class II skeletal malocclusion has a retrusive mandible relative to the maxilla.
Class III skeletal malocclusion involves a protrusive mandible relative to the maxilla.

Facial Types

Brachyfacial: Broad, square face with strong chin and flat mandibular plane.
Dolichofacial: Long, narrow face with steep mandibular plane and concave profile.
Mesofacial: Average face in balanced proportions.

Growth Patterns

Width growth concludes before adolescent growth spurt.
Length growth continues through puberty.
Height growth is typically longer than length growth.

Crossbite Factors

Three key factors affecting crossbite:
- Genetics: Skeletal constriction affecting jaw growth.
- Environmental influences: Including premature loss of teeth, crowding, and trauma.
- Habits: Such as tongue thrusting and mouth breathing.

Crossbite Characteristics

Dental crossbite involves displacement of teeth or occlusal shifting.
Skeletal crossbite generally results from maxillary constriction.

Class I and Class II Malocclusion Causes

Class II dental malocclusion can result from early loss of primary molars and molar rotation.
Class II skeletal malocclusion may result from maxillary protrusion or mandibular retrusion.

Class III Malocclusion Characteristics

Class III occlusion includes proclined upper incisors, retroclined lower incisors, and a concave profile.
Factors causing Class III may include early loss of teeth or mandible prognatism.

Evaluation Planes

Transverse plane evaluations examine midline deviation and crossbite.
Vertical plane evaluations assess facial patterns, opening, and deep bites.

Open Bite Types and Causes

Anterior open bite occurs when incisor teeth fail to overlap, often due to habits or excessive eruption.
Posterior open bite involves posterior teeth failing to occlude, potentially from habits or ankylosis.

Deep Bite Characteristics

Anterior deep bite results from excessive overlap of upper incisors over lower incisors.
Causes include a deep curve of Spee or lack of anterior contact.

Tooth Identification Systems

Primary dentition use EDCBA in two rows for tooth identification.
Permanent dentition utilizes a numerical system from 8 to 1 for the upper arch and from 1 to 8 for the lower arch.

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Description

Explore the classification of dental and skeletal deviations in this insightful flashcard quiz. Understand how morphological discrepancies contribute to diagnosis and treatment planning in orthodontics. Ideal for students seeking to grasp foundational concepts in orthodontics and malocclusion classification.