Podcast
Questions and Answers
What is the role of the dental follicle in tooth eruption?
What is the role of the dental follicle in tooth eruption?
Which theory suggests that the periodontal ligament contributes to tooth movement?
Which theory suggests that the periodontal ligament contributes to tooth movement?
What process is incorrectly identified as the cause of eruptive movements in previous theories?
What process is incorrectly identified as the cause of eruptive movements in previous theories?
What can cause limited tooth movement according to the vascular pressure theory?
What can cause limited tooth movement according to the vascular pressure theory?
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In which stage of passive eruption does the anatomical crown remain constant, while the clinical crown continues to change?
In which stage of passive eruption does the anatomical crown remain constant, while the clinical crown continues to change?
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At what point does the first stage of passive eruption occur in deciduous teeth?
At what point does the first stage of passive eruption occur in deciduous teeth?
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Which of the following describes a characteristic of the fourth stage of passive eruption?
Which of the following describes a characteristic of the fourth stage of passive eruption?
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Which factor is NOT associated with periodontal ligament traction according to its theory?
Which factor is NOT associated with periodontal ligament traction according to its theory?
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In the pre-eruptive phase, where do maxillary permanent molars face?
In the pre-eruptive phase, where do maxillary permanent molars face?
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What is true about mandibular permanent molars during the pre-eruptive phase?
What is true about mandibular permanent molars during the pre-eruptive phase?
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What marks the start of the eruptive (prefunctional) phase?
What marks the start of the eruptive (prefunctional) phase?
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Which of the following describes a characteristic of the eruptive phase?
Which of the following describes a characteristic of the eruptive phase?
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What does the gubernacular canal connect?
What does the gubernacular canal connect?
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What is associated with tooth eruption according to clinical signs?
What is associated with tooth eruption according to clinical signs?
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What structures are formed during the eruptive phase?
What structures are formed during the eruptive phase?
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What is the correct sequence of events in the pre-eruptive phase related to jaw growth?
What is the correct sequence of events in the pre-eruptive phase related to jaw growth?
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What occurs during jaw growth in length for deciduous teeth?
What occurs during jaw growth in length for deciduous teeth?
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What type of movement involves both bone resorption and deposition for tooth movement?
What type of movement involves both bone resorption and deposition for tooth movement?
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In which direction do all tooth germs move during jaw growth in width?
In which direction do all tooth germs move during jaw growth in width?
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Where do permanent incisor and canine tooth germs develop in relation to their predecessors?
Where do permanent incisor and canine tooth germs develop in relation to their predecessors?
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What describes the development position of premolars during the pre-eruptive phase?
What describes the development position of premolars during the pre-eruptive phase?
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What happens during eccentric growth of a tooth germ?
What happens during eccentric growth of a tooth germ?
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Which type of movement primarily occurs during the pre-eruptive phase in relation to the growing jaw?
Which type of movement primarily occurs during the pre-eruptive phase in relation to the growing jaw?
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During jaw growth in height, deciduous teeth move in which direction?
During jaw growth in height, deciduous teeth move in which direction?
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What is the primary function of osteoclasts during tooth eruption?
What is the primary function of osteoclasts during tooth eruption?
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Which phase begins when the tooth reaches the occlusal plane?
Which phase begins when the tooth reaches the occlusal plane?
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What leads to the formation of an epithelial-lined canal for tooth eruption?
What leads to the formation of an epithelial-lined canal for tooth eruption?
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Which movement is NOT a type of eruptive tooth movement?
Which movement is NOT a type of eruptive tooth movement?
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What does the root formation theory primarily attribute to tooth eruption?
What does the root formation theory primarily attribute to tooth eruption?
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What is the role of desmolytic enzymes during tooth eruption?
What is the role of desmolytic enzymes during tooth eruption?
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Which theory suggests that bone remodeling is linked to tooth eruption?
Which theory suggests that bone remodeling is linked to tooth eruption?
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During which phase does compensation for occlusal wear primarily occur?
During which phase does compensation for occlusal wear primarily occur?
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What is the main function of the periodontal ligament in tooth eruption?
What is the main function of the periodontal ligament in tooth eruption?
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Which type of tooth movement occurs around a transverse axis?
Which type of tooth movement occurs around a transverse axis?
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What is the definition of active eruption in tooth development?
What is the definition of active eruption in tooth development?
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During which phase does the pre-eruptive phase begin?
During which phase does the pre-eruptive phase begin?
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What does the anatomical crown of a tooth refer to?
What does the anatomical crown of a tooth refer to?
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What is passive eruption characterized by?
What is passive eruption characterized by?
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Which of the following best describes the changes in the pattern of tooth movement during the pre-eruptive phase?
Which of the following best describes the changes in the pattern of tooth movement during the pre-eruptive phase?
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What factors are most likely to influence the periodontium?
What factors are most likely to influence the periodontium?
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What are the primary muscles involved in masticatory functions?
What are the primary muscles involved in masticatory functions?
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Which of the following describes the term 'shedding' in dentistry?
Which of the following describes the term 'shedding' in dentistry?
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Study Notes
Course Objectives
- Students will be able to identify the geometric outlines of tooth crown surfaces and their physiological significance.
- Students will be able to list and explain factors affecting the periodontium.
- Students will be able to describe the temporomandibular joint, its components, and mastication muscles.
- Students will be able to list different mandibular movements and compensatory curves.
- Students will be able to describe the phases of permanent tooth development in the dental arch.
- Students will be able to identify the composition and function of saliva.
- Students will be able to define eruption, its phases, and movements in each phase.
- Students will be able to define and describe tooth shedding mechanisms, clinical considerations, and patterns of shedding in anterior and posterior teeth.
Tooth Eruption
- Tooth eruption is the movement of teeth from their developmental position to their functional position in the oral cavity.
- It involves both bodily and eccentric movements of teeth.
- The process begins at different times for the different types of deciduous and permanent teeth.
Terminology of Eruption
- Active Eruption: The actual movement of the tooth from the developmental site to its position in the dental arch.
- Passive Eruption: Tooth movement doesn't happen but instead, the gums recede.
- Clinical Crown: The portion of the tooth visible in the oral cavity.
- Anatomical Crown: The part of the tooth covered by enamel.
Histological Phases of Eruption
- Information will be discussed in various stages and subtopics regarding the pre-eruptive phase.
Phases of Eruption
- This section will cover when different phases start and end, as well as ongoing events and movement types during each phase.
Pre-eruptive Phase
- Begins during the early bell stage of tooth development.
- Ends with the beginning of root formation.
- Deciduous teeth initially have enough space for each tooth germ, but crowding occurs later due to rapid growth.
- The crowding is relieved by jaw growth in length, width, and height. This bodily movement allows teeth to move forward, backward, outward, and occlusally.
Movement of Deciduous Teeth
- Jaw growth in length moves anterior teeth forward and posterior teeth backward.
- Growth in width moves all teeth outward from the center.
- Jaw growth in height moves the teeth upwards.
- Bodily movement and eccentric growth are two types of movements in the pre-eruptive stage.
- Deciduous teeth initially have enough space for each tooth germ, but crowding occurs later due to rapid growth, and the crowding is relieved by the jaw growing in length, width, and height.
Premolars tooth germs
- First develop on the lingual aspect of their deciduous predecessors at the level of their occlusal surfaces and in the same bony crypt.
- The tooth germs occupy a more apical position as the predecessor teeth erupt and lie in their own bony crypts, and their positions are still lingually situated.
- By time, the primary molars have come into occlusion, and the crowns of the developing premolars occupy a position between the roots of the primary molars.
Permanent teeth without Deciduous Predecessors
- Maxillary permanent molars have occlusal surfaces facing downward and distally.
- Mandibular permanent molars have occlusal surfaces inclined mesially.
- The maxilla molars are in the tuberosity, facing distally, while mandibular molars are in the base of the ramus, facing mesially.
- They tilt to be upright with growth of the mandible.
Eruptive Phase
- Starts when the root formation begins.
- It ends when the tooth reaches occlusion.
- The clinically visible portion of the developing permanent teeth may cause discomfort or pain.
- Tooth growth may also lead to increased salivation, but no bleeding occurs.
Eruption Path of Succedaneous Teeth
- Gubernacular canal connects permanent teeth to the oral epithelium.
- Contains remnants of the dental lamina (Gubernacular cord).
Location of Gubernacular Canal
- Anteriorly, located lingual to primary anterior teeth.
- Posteriorly, located between the roots of primary molars.
Changes in Tissues Overlying Erupting Tooth
- Bone resorption, degeneration of connective tissue, and epithelial proliferation and fusion are crucial for tooth eruption.
- These processes form a central mass that degenerates into an epithelial-lined canal through which the tooth erupts without bleeding.
Osteoclasts Erode Jaw Bone
- Osteoclasts are crucial in the process of erupting adult teeth.
- Osteoclasts erode the jaw bone to make way for the erupting tooth.
Histogenesis of Dento-gingival Junction
- Desmolytic enzymes and epithelial plugs are involved. The final formation of the Dentogingival junction arises from reduced enamel epithelium.
Tooth Movement Phases
- Eruptive Phase: Characterized by root formation, supporting structures development (cementum, PDL, and bone) and formation of the dento-gingival junction.
- Post-eruptive Phase: Begins when the tooth reaches the occlusal plane. The tooth maintains position while the jaw grows, compensates for wear (axial movement, mesial drift). This phase ends at the end of the tooth's lifespan.
- Tooth movement types include axial (bodily, tilting), occlusal, and rotary.
Theories of Eruption Mechanism
- Root Formation Theory: Proliferating root impinges on a fixed base, creating an apically directed force that causes occlusal movement.
- Bone Remodeling Theory: Selective deposition and resorption of bone linked to tooth eruption. Though initially considered a cause of eruption, this remodeling process is now recognized as a byproduct of eruptive movements.
Dental Follicle Theory
- The dental follicle is important for tooth eruption.
- If the follicle is removed, no eruptive pathway forms.
- A replica of the germ will erupt and thus establish a pathway.
Periodontal Ligament Traction Theory
- Periodontal ligament cells and fibers pull the tooth into occlusion.
- Factors include fibroblast contractile properties, connection with collagen fibers, and oblique alignment of PDL collagen fibers.
Vascular Pressure Theory
- Local volume changes in periapical regions, potentially due to arterial pulse or swelling, can influence limited tooth movement.
Passive Eruption
- This phase can be categorized into First, Second, Third, and Fourth stages, that last until the tooth is lost. Gingival recession happens as part of passive eruption.
Stages of Passive Eruption
- Detailed explanation of the first, second, third, and fourth stages, including how the stages occur as the tooth is erupting.
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