Permanent Tooth Eruption Quiz

Permanent Tooth Eruption

• Permanent teeth, also known as succedaneous teeth, erupt behind the roots of the primary teeth.
• An exception is the maxillary incisors, which erupt more forward.
• The eruption process for a permanent tooth is similar to that of a primary tooth.

Eruption Process for Permanent Tooth

• During eruption, the reduced enamel epithelium (REE) fuses with oral epithelium.
• This tissue degenerates, leaving an epithelial-lined eruption tunnel.

Primary Tooth Eruption Timeline

• Central incisors erupt 6-12 months.
• Lateral incisors erupt 9–16 months.
• Canines (Cuspids) erupt 16-23 months.
• First molars erupt 12–18 months.
• Second molars erupt 24–30 months.
• Most children possess all 20 primary teeth by age 3.
• Primary teeth typically begin to shed around age 6.

Permanent Tooth Eruption Timeline

• First Molars: 6–7 years
• Central Incisors: 6–8 years
• Lateral Incisors: 7–9 years
• Canines: 9–12 years
• Premolars: First Premolars: 10–11 years, Second Premolars: 11–12 years.
• Second Molars: 11–13 years
• Third Molars (Wisdom Teeth): 17-21 years
• Most permanent teeth have fully erupted by the early 20s.

Disturbances During Tooth Eruption

• Premature eruption:

  • Natal teeth: primary teeth erupting at birth.
  • Neonatal teeth: teeth erupting in the first 30 days of life.

• Delayed eruption:

  • Potential causes include systemic conditions, genetics, poor nutrition, hormonal disorders, Down syndrome, chemotherapy, prematurity, low birth weight, and tobacco smoke.

• Multiple unerupted teeth:

  • A rare condition where permanent or deciduous teeth fail to erupt.
  • Potential causes include obstruction from primary teeth or bone surrounding the unerupted tooth.

• Embedded or impacted teeth:

  • Unerupted teeth due to a lack of eruptive force.
  • Impacted teeth are prevented from erupting by other teeth.
  • Crowding, premature loss of primary teeth, or tooth rotation during eruption can all impact this.
  • Third molars and maxillary cuspids are most commonly impacted.

• Dentigerous Cyst (Follicular Cyst):

  • Develops from the reduced enamel epithelium (REE) after the crown formation and maturation.
  • Fluid accumulation above an unerupted tooth creates a cyst.

Abnormal Exfoliation (Loss) of Primary Teeth

• Abnormal shedding or loss of primary teeth.
• Potential causes include dental anomalies (e.g., enamel hypoplasia), trauma, and untreated dental disease.
• Genetic disorders can also contribute to the problem.

Abnormal Occlusion (Malocclusion)

• Occlusion is the relationship between the maxillary and mandibular teeth when the jaws are fully closed.
• Unnatural occlusal stress can lead to disharmony, and impact the functions for which the teeth were designed.
• Causes include genetic factors (running in families), early tooth loss, and various habits (thumb-sucking).
• Further causes also include differences in jaw size, crowding/spacing of teeth, impact teeth, abnormal tooth eruption paths, and the loss of a tooth.

Centric Occlusion (CO)

• The voluntary position of the teeth that allows for maximum contact.
• Each tooth contacts two opposing teeth except for the mandibular central incisors and maxillary third molars.

Tooth Loss and Centric Occlusion

• The loss of a tooth for a prolonged period often leads to the tipping of neighbouring teeth, misalignment and supereruption of the opposing tooth, which affects the entire dentition.

Angles Classification of Malocclusion

• Classifies malocclusion based on the relationship of the maxillary and mandibular arches.

Normal Overjet

• The maxillary arch horizontally overlaps the mandibular arch in centric occlusion by 1-3 mm.

Overjet

• The distance between the incisal edges of the maxillary and mandibular incisors measured perpendicular to the occlusal surfaces.
• The measurement is generally taken after the patient has been placed in centric occlusion using a periodontal probe.

Normal Overbite

• The maxillary arch vertically overlaps the mandibular arch in centric occlusion, which is measured in millimeters using a periodontal probe placed perpendicular to the edge of the maxillary incisor and the mandibular incisor.

Healthy vs Unhealthy Overbite

• A normal amount of vertical overlap between the two arches, 2-5mm between the anterior segment of the two arches, allows for contact between the posterior teeth when chewing.
• Excessive overjet or overbite are clinically classified as malocclusions.

Underbite

• The mandibular arch extends forward beyond the maxillary arch.

Contacts

• Teeth on the same arch create contacts on their proximal surfaces.
• The last tooth in each arch lacks distal contact.
• Contacts protect interdental papillae and stabilize teeth within the arch.
• Open contacts can cause food impaction and trauma to the interdental gingiva.

Passive Eruption

• The gradual recession of the gingiva and underlying alveolar bone during eruption.
• The tooth itself does not move, but the surrounding soft tissues shrink.

Post-eruptive Occlusion - PDL Health

• Poor home care can result from poor occlusion.
• The appearance is negatively impacted.
• Most malocclusions are treatable.
• Crowding and overjet are common issues in teenagers and can be treated.

Test your knowledge on the process and timeline of permanent tooth eruption. This quiz covers the distinctions between permanent and primary teeth, as well as the eruption timeline for both types. Understand the key stages in dental development.