Intro Flashcards
List common occlusal and dental anomalies.
Crowding, spacing.
Increased or reverse overjet.
Anterior open bite, deep bite.
Hypodontia, supernumeraries.
Define occlusion and its classifications.
Occlusion: Arrangement of upper and lower teeth in contact.
Ideal Occlusion: Hypothetical; teeth perfectly positioned.
Normal Occlusion: Minor deviations without functional or aesthetic issues.
Malocclusion: Significant deviations causing functional or aesthetic problems.
What are Andrews’ six keys to ideal occlusion?
Molar relationship.
Crown angulation (mesio-distal tip).
Crown inclination.
Absence of rotations.
Tight contacts (no spaces).
Flat occlusal plane.
What is the molar relationship?
The distal surface of the upper first permanent molar’s distobuccal cusp occludes with the mesial surface of the lower second molar’s mesiobuccal cusp.
What are the three primary steps of an orthodontic assessment?
History (presenting complaint, medical/dental/family/social history).
Examination (extra-oral and intra-oral).
Special investigations (radiographs, models, vitality tests).
How are facial skeletal patterns assessed in three planes?
Antero-Posterior (AP): Class I, II, III.
Vertical: Lower Anterior Face Height (LAFH)/Total Anterior Face Height (TAFH) ratio.
Transverse: Symmetry, e.g., midline deviations.
What are Class I, II, and III skeletal patterns?
Class I: Maxilla 2-3 mm in front of the mandible.
Class II: Maxilla significantly ahead or mandible retruded.
Class III: Maxilla retruded or mandible significantly forward.
Define Frankfort-Mandibular Plane Angle (FMPA) and its significance.
increased/decreased
FMPA: Angle between Frankfort plane and mandibular plane.
Increased FMPA: Associated with vertical growth/open bites.
Decreased FMPA: Associated with horizontal growth/deep bites.
Explain the role of soft tissues in orthodontics.
Lips: Competency influences tooth alignment.
Tongue: Position and swallowing affect occlusion (e.g., anterior open bite).
Habits: Thumb-sucking can alter dental arches.
Speech: Lisping
Describe the typical radiographs used in orthodontic assessment and their purposes.
OPT (Orthopantomogram): Evaluate overall dentition, impacted teeth, and bone structure.
Lateral Cephalogram: Analyze skeletal relationships and growth patterns.
Maxillary Anterior Occlusal Radiograph: Assess anomalies in the maxillary arch.
Explain the concept of mandibular displacement.
Discrepancy between retruded contact position (RCP) and intercuspal position (ICP).
May cause pain, joint clicking, deviation on opening, and centric occlusion discrepancies.
What is the significance of the Lower Anterior Face Height (LAFH) to Total Anterior Face Height (TAFH) ratio?
Normal ratio: 50%.
Increased ratio: Associated with excessive vertical growth (e.g., open bites).
Decreased ratio: Associated with reduced vertical growth (e.g., deep bites).
What are the intra-oral examination components during an orthodontic assessment?
Assess oral hygiene and periodontal health.
Check tooth count and note any missing, extra, or malformed teeth.
Evaluate crowding, rotations, inclination, and angulation of teeth.
Palpate for unerupted canines.
Differentiate between Class II Division 1 and Division 2 malocclusion.
Class II Division 1: Proclined upper incisors; increased overjet.
Class II Division 2: Retroclined upper incisors; minimal or increased overjet.
What are the orthodontic impacts of tongue thrust?
Cause or Effect: May cause or adapt to anterior open bite (AOB).
Can lead to AOB relapse if the habit persists after treatment.
What are the occlusal features of a sucking habit (e.g., thumb or digit sucking)?
- Proclination of upper anteriors.
- Retroclination of lower anteriors.
- Localized anterior open bite (AOB) or incomplete overbite (OB).
- Narrowing of the upper arch, potentially leading to:
Unilateral posterior crossbite.
effects superimposed on existing skeletal pattern & incisor relationship
How are teeth assessed for occlusion during intra-oral examination?
Incisor relationship (Class I, II div 1, II div 2, III).
Overjet, overbite/open bite.
Molar and canine relationships (Angle’s classifications).
Crossbites, midline alignment.
Classify incisor relationships based on the British Standards Institute.
Class I: Lower incisor edges occlude with/just below upper cingulum plateau.
Class II:
Division 1: Proclined upper incisors; increased overjet.
Division 2: Retroclined upper incisors; reduced/normal overjet.
Class III: Lower incisors anterior to upper cingulum; reverse/reduced overjet.
What are the uses of study models in orthodontics?
Evaluate arch relationships and occlusion.
Plan appliance designs.
Monitor treatment progress.
What are Angle’s Classes of Malocclusion?
- Class I (Neutrocclusion):
The mesiobuccal cusp of the upper first molar occludes with the buccal groove of the lower first molar.
Normal molar relationship, but there may still be crowding, spacing, or other irregularities.
- Class II (Distocclusion):
The mesiobuccal cusp of the upper first molar is anterior to the buccal groove of the lower first molar.
Subdivided into:
Division 1: Proclined upper incisors; increased overjet.
Division 2: Retroclined upper central incisors; reduced overjet.
- Class III (Mesiocclusion):
The mesiobuccal cusp of the upper first molar is posterior to the buccal groove of the lower first molar.
Associated with reverse overjet (underbite).
What are the canine relationships in orthodontics?
Class I:
The upper canine cusp lies in the embrasure between the lower canine and first premolar.
Class II:
The upper canine cusp lies mesial (ahead) to the embrasure between the lower canine and first premolar.
Class III:
The upper canine cusp lies distal (behind) to the embrasure between the lower canine and first premolar.
What are the main aims of orthodontic treatment?
- Achieve stable, functional, and aesthetic occlusion.
- Address skeletal and dental discrepancies.
- Prepare for restorative work if needed.
Explain the Index of Orthodontic Treatment Need (IOTN).
A tool to assess the need for orthodontic treatment based on:
Dental Health Component (DHC): Clinical severity of malocclusion.
Aesthetic Component (AC): Impact on appearance.
What is a potential cause of hemifacial microsoma?
Lack of neural crest cells on affected side
