Podcast
Questions and Answers
What is the primary function of the soft tissues in the oral cavity?
What is the primary function of the soft tissues in the oral cavity?
Which part of the tooth is responsible for its visibility above the gum line?
Which part of the tooth is responsible for its visibility above the gum line?
What are the functions of the masticatory mucosa?
What are the functions of the masticatory mucosa?
What distinguishes maxillary canines from mandibular canines?
What distinguishes maxillary canines from mandibular canines?
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Which of the following tooth surfaces is closest to the midline?
Which of the following tooth surfaces is closest to the midline?
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What is true about the structure of mandibular molars?
What is true about the structure of mandibular molars?
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What is the primary role of the periodontal ligament?
What is the primary role of the periodontal ligament?
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During which stage does calcification of teeth begin?
During which stage does calcification of teeth begin?
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What is an effect of the mesial drift of permanent molars?
What is an effect of the mesial drift of permanent molars?
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What happens to the roots of a deciduous tooth during exfoliation?
What happens to the roots of a deciduous tooth during exfoliation?
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Which structure is responsible for housing the tooth sockets?
Which structure is responsible for housing the tooth sockets?
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How are anterior teeth primarily classified?
How are anterior teeth primarily classified?
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Which of the following describes a distinct feature of maxillary molars?
Which of the following describes a distinct feature of maxillary molars?
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What defines the incisal edges of incisors?
What defines the incisal edges of incisors?
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What is the eruption age for maxillary first molars?
What is the eruption age for maxillary first molars?
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Which molars have a less developed distolingual cusp compared to their first counterparts?
Which molars have a less developed distolingual cusp compared to their first counterparts?
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Which characteristic pertains to the roots of maxillary molars?
Which characteristic pertains to the roots of maxillary molars?
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What feature distinguishes mandibular first molars from mandibular second molars?
What feature distinguishes mandibular first molars from mandibular second molars?
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What developmental feature is specific to maxillary first molars?
What developmental feature is specific to maxillary first molars?
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How are mandibular second molars characterized compared to mandibular first molars?
How are mandibular second molars characterized compared to mandibular first molars?
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What characteristic does the eruption of primary teeth begin with?
What characteristic does the eruption of primary teeth begin with?
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What is the primary purpose of deciduous teeth?
What is the primary purpose of deciduous teeth?
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What defines a Class II occlusion classification?
What defines a Class II occlusion classification?
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Which feature is indicative of deep bite malocclusion?
Which feature is indicative of deep bite malocclusion?
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At what age do mandibular first molars typically erupt?
At what age do mandibular first molars typically erupt?
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What distinguishes the buccal aspect of the mandibular first molar?
What distinguishes the buccal aspect of the mandibular first molar?
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What is the expected consequence of resorption of deciduous roots?
What is the expected consequence of resorption of deciduous roots?
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What defines the central developmental groove of a tooth?
What defines the central developmental groove of a tooth?
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Study Notes
Oral Anatomy
- The face area includes the eyes, nose, cheeks, and lips.
- Oral tissues include soft tissues (gums, tongue, lips) and hard tissues (teeth, palate).
- The palate is the roof of the mouth, divided into the hard palate (anterior) and soft palate (posterior).
- The throat area includes the pharynx and larynx.
- The floor of the mouth includes the tongue and surrounding soft tissues.
Tooth Anatomy
- The crown is the visible portion of the tooth above the gum line.
- The root is the portion of the tooth below the gum line.
- Tooth surfaces include: lingual, facial, buccal, mesial, distal and proximal.
- The incisal/occlusal surface is the biting/chewing surface.
Tooth Relationships
- The contact area is the flattened portion of the tooth where it touches the adjacent tooth.
- Interproximal spaces are triangular-shaped spaces between teeth, formed by bone and the proximal surfaces.
- Tooth contours allow for proper food deflection and tongue resting.
Dental Arches and Dentition
- The maxillary arch is the upper dental arch.
- The mandibular arch is the lower dental arch.
- Primary dentition consists of 20 deciduous (baby) teeth.
- Secondary dentition consists of 32 permanent teeth.
Tooth Development and Eruption
- Calcification is the hardening of tooth tissues by the deposition of mineral salts.
- Mamelons are the incisal ridges on newly erupted incisors.
- Premolar lobes and cusps vary in number, providing a unique shape for each tooth.
- Molar lobes and cusps are more complex and are often categorized by the presence of a fifth lobe.
- Mandibular teeth typically erupt before maxillary teeth of the same type.
The Tissue
- The gingival unit includes the free gingiva, attached gingiva, and alveolar mucosa.
- The attachment unit (attachment apparatus) includes the cementum, Sharpey's fibers, and periodontal ligament.
- The alveolar process is the bony structure that houses the tooth sockets.
- The mucosa is a thin, freely movable tissue.
Anterior Teeth and Premolars
- Incisors are used for cutting and biting into food.
- Canines are used for gripping and tearing food.
- Premolars, also known as bicuspids, have two cusps each.
Molars
- Molars are responsible for crushing and grinding food.
- Maxillary molars have broader crowns and typically have three roots.
- Mandibular molars have broader crowns and typically have two roots.
Roots
- The pulp tissue of the root contains nerves that only emit a pain response when stimulated.
- The apical foramen is the orifice in the apex of the root where vessels enter and exit.
- Root canals contain nerves and blood vessels that leave the tooth through the root apex.
Anterior Teeth: Incisors and Canines
- Maxillary Central Incisors: The largest and widest incisors.
- Maxillary Lateral Incisors: Smaller than centrals, with more prominent features.
- Mandibular Central Incisors: The smallest teeth in the mouth.
- Mandibular Lateral Incisors: Larger and wider than central incisors, with distinct lingual features.
Canines
- Maxillary Canines: Have the bulkiest crowns and a well-developed lingual cingulum.
- Mandibular Canines: Smoother lingual surface, with a less developed cingulum.
Premolars
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Maxillary 1st Premolar: Has two roots (buccal and lingual) and well-developed facial cusps.
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Maxillary 2nd Premolar: Usually single-rooted, with a more rounded crown.
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Mandibular 1st Premolar: Similar to the mandibular canine, with a single root.
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Mandibular 2nd Premolar: Larger than the first premolar, with either a three-cusp or two-cusp form.### Permanent Molars
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Permanent molars are nonsuccedaneous or accessional, which means they do not replace any primary teeth.
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The first permanent molars erupt distal to the primary second molars.
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Mandibular teeth typically erupt before maxillary teeth.
Maxillary 1st Molars
- Erupts between 6 and 7 years old.
- The largest teeth in the maxillary arch.
- Possesses three well-developed major cusps and one minor cusp (distolingual cusp, or tubercle, of Carabelli).
- There are two cusps on the buccal side and two on the lingual side.
- Contains three widely separated roots.
Maxillary 2nd Molars
- Erupts between 11 and 13 years old.
- Crowns are shorter and narrower than the first maxillary molars.
- Does not have a fifth lobe.
- The distolingual cusp is less developed.
- Roots are closer together and may be fused.
Mandibular 1st Molars
- Erupts at 6 years old.
- Usually the first permanent teeth to erupt.
- Typically contains five cusps: two buccal, two lingual (major), and one distal (minor).
- The largest teeth in the mandibular arch.
- Generally has two roots: mesial and distal.
Mandibular 2nd Molars
- Erupts between 11 and 13 years old.
- Resembles the mandibular first molars buccally and lingually.
- All four cusps are nearly equal in size.
- Occlusally, the second molars have a more rectangular shape.
Maxillary Molar Roots
- Trifurcated, with mesiobuccal, distobuccal, and lingual roots.
- Roots connect to one root trunk for a sturdy anchor.
- The lingual root is the longest, and the distobuccal root is the shortest.
- All three roots are visible from the buccal view.
- The bifurcation point is about 4 mm apical to the cervical line.
- Contains a pulp chamber and three main pulp canals, one for each root.
Mandibular Molar Roots
- Two roots: mesial and distal.
- The mesial root is longer, stronger, and curves mesially before turning distally.
- The distal root is straight and may curve at the apical third.
Deciduous Teeth and Occlusion Review
- There are 20 total deciduous teeth.
- Resemble permanent teeth but are:
- Shorter crowns
- Whiter appearance
- Have spaces between teeth that grow as the jaw grows
Eruption Dates
- Mandibular teeth usually erupt first.
- The entire eruption process takes about 2-3 years.
- Central Incisors: 6-12 months
- Lateral Incisors: 7-13 months
- First Molars: 12-19 months
- Canines: 16-22 months
- Second Molars: 21-33 months
Importance of Deciduous Teeth
- Maintain space for permanent teeth.
- Allow for bone growth of dental arches.
- Spaces develop between teeth as bone grows:
- Primate space: between maxillary lateral incisor and canine, or between mandibular canine and first molar
- Leeway spaces: between first and second molars
- Leeway spaces provide extra space for permanent canines, first and second premolars.
- Resorption of deciduous roots helps guide eruption of permanent replacements.
- If a deciduous tooth is missing, the permanent counterpart will not form.
- If a deciduous tooth is compromised, it may not leave enough room for the permanent replacement.
Mixed Dentition
- A transition period when both primary and permanent teeth are present.
Occlusion Development
- Begins with the eruption of primary teeth.
- Primary molars erupt around 16 months, establishing intercuspation.
Primary Occlusion
- Has three anteroposterior molar relationships called steps or planes:
- Mesial step: Mandibular molars are more mesial than maxillary counterparts.
- Flush terminal plane: Distal of deciduous second molars are even.
- Distal step: Maxillary molars are more mesial.
- Diastemae: spaces created when dental arches grow but teeth remain the same size.
Permanent Occlusion
- Permanent molars erupt and push the spaces between teeth closed.
- Leeway space is gained when permanent premolars replace deciduous ones.
- The mandible continues to grow ensuring a Class I relationship.
Malocclusions
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Deep bite:
- Condyle head displaced distally.
- Posterior teeth don't erupt enough.
- Hyperactive masticatory muscles.
- Condyle growth angle causes less mesial jaw development.
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Horizontal alignment:
- Tongue pushes teeth outward.
- Cheek/lip muscles keep teeth from going too far.
- Balance brings teeth into alignment.
- Disruption in balance leads to malocclusion.
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Vertical alignment:
- Mandibular posterior teeth crown tip lingually, roots tip laterally.
- Maxillary posterior teeth crowns have a slight buccal inclination, roots have a slight lingual inclination.
- Anterior teeth have a slight labial protrusion and lateral incline.
- All teeth have a slight mesial inclination.
Centric Occlusion
- The position of the mandible relative to the maxillae.
- Determined by how teeth fit together when jaws are closed.
- Related to tooth occlusion, not muscle or bone.
Overjet, Overbite, and Crossbite
- Overjet: Horizontal overlap of maxillary teeth over mandibular.
- Overbite: Vertical overlap of maxillary anterior teeth over mandibular.
- Crossbite: Mandibular teeth located facial to maxillary counterparts.
Occlusal Classifications
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Skeletal:
- Class I: Maxilla and mandible in normal relationship.
- Class II: Mandible retruded, distal relationship with maxilla.
- Class III: Mandible protruded, mesial relationship with maxilla.
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Dental:
- Molar Classification:
- Class I: Occlusal Relationship (Neutroclusion)
- Class II: Occlusal Relationship (Distoclusion).
- Class III: Occlusal Relationship (Mesioclusion).
- Canine Classification:
- Class I: Mandibular canine distal within premolar width of maxillary.
- Class II: Mandibular canine distal beyond premolar width of maxillary.
- Class III: Mandibular canine mesial beyond premolar width of maxillary.
- Molar Classification:
Other Occlusal Concepts
- Protrusion: Mandible moves forward, only anterior teeth should touch.
- Premature contact: One tooth hits harder than others, can damage TMJ.
Ideal Occlusion
- Occlusal plane almost flat with a slight curve of Spee.
- Tight proximal contacts, no spaces.
- No rotated teeth.
- Symmetric, well-formed arches.
- Crowns tipped slightly mesially.
- Maxillary third molar almost straight up and down.
- Maxillary first molar is stolarized, tipped mesially.
Eruption Schedule
- All 1st molars erupt at 6 years old.
- All 1st premolars erupt at 10-12 years old.
- All lateral incisors erupt at 7-8 years old.
- All 2nd molars erupt at 11-13 years old.
- All 2nd premolars erupt at 10 -12 years old.
- Mandibular canines erupt at 9-12 years old.
- Maxillary canines erupt at 11-12 years old.
- Mandibular central incisors erupt at 6 years old.
- Maxillary central incisors erupt at 7-8 years old.
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