Phases of Eruption of Permanent Teeth
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Questions and Answers

What is the average amount of crowding in the incisor segment when permanent incisors erupt?

  • 0.9 mm
  • 1.7 mm
  • 1.6 mm (correct)
  • 2.5 mm
  • Which teeth erupt at 6 years of age during the first phase of permanent tooth eruption?

  • Canines
  • First premolars
  • First molars (correct)
  • Central and lateral incisors
  • What is the difference in size between primary molars and premolars replaced by them called?

  • Molar convergence
  • Dental arch development
  • Leeway space of Nance (correct)
  • Occlusal relationship
  • What is the purpose of the Leeway space of Nance in the dental arch development?

    <p>To align permanent incisors and adjust the occlusal relationship of molars</p> Signup and view all the answers

    During which phase of permanent tooth eruption do the permanent central and lateral incisors erupt?

    <p>Second phase</p> Signup and view all the answers

    What is the function of the first permanent molars during the first phase of eruption?

    <p>To support the deciduous dentition</p> Signup and view all the answers

    What happens to the canines during the fourth phase of permanent tooth eruption?

    <p>They force themselves by wedging between the lateral incisors and first premolars</p> Signup and view all the answers

    What is the purpose of the second molars during the fourth phase of permanent tooth eruption?

    <p>To support the canines during their wedging</p> Signup and view all the answers

    At what age is the permanent dental arch typically completed?

    <p>12 years</p> Signup and view all the answers

    What is the function of the primate space?

    <p>To preserve a space for the permanent teeth for proper occlusion</p> Signup and view all the answers

    What is the name of the curve that occurs in the sagittal plane and is observed from a point opposite the first molars?

    <p>Curve of Spee</p> Signup and view all the answers

    What is the direction of the inclination of the crowns of maxillary posterior teeth?

    <p>Buccally</p> Signup and view all the answers

    Why does the Curve of Wilson become deeper as you move posteriorly?

    <p>Because the inclinations of posterior teeth become greater as you go posterior</p> Signup and view all the answers

    What is the name of the phase that occurs after the completion of the permanent dental arch?

    <p>Fifth phase</p> Signup and view all the answers

    What is the name of the space that occurs between the upper B and C teeth in the maxillary arch?

    <p>Primate space</p> Signup and view all the answers

    What is the term for the curved planes of the dental arches that occur in the upper and lower arches?

    <p>Curved occlusal planes</p> Signup and view all the answers

    What is the term used to describe the horizontal overlap of the maxillary anterior teeth over the mandibular teeth?

    <p>Overjet</p> Signup and view all the answers

    What is the term used to describe the vertical overlap of the maxillary anterior teeth over the mandibular teeth?

    <p>Overbite</p> Signup and view all the answers

    What is the shape of the dental arches in both the upper and lower jaws?

    <p>Parabolic</p> Signup and view all the answers

    How many segments do the parabolic curves of each dental arch divide into?

    <p>Three</p> Signup and view all the answers

    What is the direction of the posterior segment of the upper dental arch?

    <p>Slightly deviated lingually</p> Signup and view all the answers

    What is the reason for the posterior segment of the upper dental arch to be slightly deviated lingually?

    <p>Due to the DB convergence of the upper first molar and the location of the second and third maxillary molars</p> Signup and view all the answers

    What happens to the distal convergence of the upper molars as we go posterior?

    <p>It increases</p> Signup and view all the answers

    What happens to the buccolingual dimension of the upper molars as we go posterior?

    <p>It decreases</p> Signup and view all the answers

    Study Notes

    Phases of Eruption of Permanent Teeth

    • The first permanent molars erupt at 6 years of age, supporting the deciduous dentition and increasing chewing efficiency to adapt to jaw growth.
    • The permanent central and then lateral incisors erupt with 1.6mm crowding in the lower incisor segment, with their permanent location and alignment established only after dental arch development is completed.
    • The 1st and 2nd premolars take the places of the deciduous molars, with a smaller size in M-D dimensions, resulting in Leeway space of Nance (average: 0.9 mm on each maxillary quadrant, 1.7 mm on each mandibular quadrant).
    • The Leeway space of Nance is utilized for the alignment of permanent incisors and for the molars to adjust the proper occlusal relation of maxillary and mandibular permanent molars.
    • The canines (corner stones) force themselves by wedging between the lateral incisors and first premolars in both jaws, with the second molars erupting distal to the first molars.
    • The eruption of the wisdom tooth marks the final phase.

    Completed Dental Arch

    • The permanent dental arch is completed at the fourth phase (end of 12 years with the eruption of 3 & 7).

    Primate Space

    • The primate space is noticed during the development of deciduous occlusion.
    • It is the space between upper B & C for maxillary teeth and between lower C & D for mandibular teeth.
    • Its function is to preserve a space for the permanent teeth for proper occlusion.

    Curves of Occlusal Planes

    • The occlusal surfaces of dental arches do not follow a flat plane but have curved surfaces.
    • The curves of the lower dental arch are concave, while those of the upper dental arch are convex.
    • The two curved planes become identical in centric occlusion.

    Curve of Spee

    • The curve is observed in the sagittal plane.
    • It is observed from a point opposite the first molars.
    • Incisal ridges of anterior teeth and buccal cusps of posterior teeth follow a curve that ends at the anterior border of the condyle.
    • This curve complements the path of the mandibular condyles in the anterio-posterior movements of the mandible.

    Curve of Wilson

    • The curve is observed in the coronal plane.
    • For each posterior tooth, the occlusal surfaces of both right and left teeth adapt to a curved plane (convex for upper and concave for lower).
    • The curve becomes deeper as you go posterior due to the increased inclination of posterior teeth.
    • The crowns of mandibular posterior teeth incline lingually, while those of maxillary posterior teeth incline buccally.

    Overbite and Overjet

    • The horizontal overlap is known as overjet (2-4 mm).
    • The vertical overlap is known as overbite (2-4 mm).

    Relationship of Anterior Teeth

    • Maxillary anterior teeth overlap mandibular teeth.
    • The incisal edges of maxillary anterior teeth are labial to the incisal edges of mandibular teeth.
    • The parabolic curves of each dental arch are divided into three segments overlapping each other.

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    Description

    This quiz covers the different phases of permanent teeth eruption into dental arches, including the first phase of molar eruption and the second phase of incisor eruption.

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