Permanent Tooth Eruption PDF

Permanent Tooth Eruption HSDH2140 EMBRYOLOGY & HISTOLOGY FALL 2024. WEEK 10 DR. JAFAR ALABDULLAH 1 Permanent Tooth Eruption ⮚The succedaneous permanent tooth erupts lingual to the roots of the shedding primary tooth as it develops. ⮚The only exception is the...

Permanent Tooth Eruption HSDH2140 EMBRYOLOGY & HISTOLOGY FALL 2024. WEEK 10 DR. JAFAR ALABDULLAH 1 Permanent Tooth Eruption ⮚The succedaneous permanent tooth erupts lingual to the roots of the shedding primary tooth as it develops. ⮚The only exception is the permanent maxillary incisors, which erupt in a more facial position. Eruption Lingual and Facial Permanent Tooth Eruption ⮚The process of eruption for a permanent (succedaneous) tooth is the same as for the primary tooth. ⮚The REE fuses with the oral epithelium to create a tissue that degenerates, leaving an epithelial‑lined eruption tunnel. Eruption of primary teeth General timeline for the eruption of primary teeth: 1.Central Incisors: 6–12 months 2.Lateral Incisors: 9–16 months 3.Canines (Cuspids): 16–23 months 4.First Molars: 12–18 months 5.Second Molars: 24–30 months Most children have a complete set of 20 primary teeth by around 3 years of age. Primary teeth typically begin to shed around age 6, making way for the permanent teeth. Shedding of primary teeth General timeline for the shedding of primary teeth: 1.Central Incisors: 6–7 years 2.Lateral Incisors: 7–8 years 3.Canines (Cuspids): 9–12 years 4.First Molars: 9–11 years 5.Second Molars: 10–12 years Most primary teeth are lost by around age 12, making way for the permanent teeth. The timing can vary among individuals, but this provides a general guideline. Eruption of permanent teeth 1.First Molars: 6–7 years 2.Central Incisors: 6–8 years 3.Lateral Incisors: 7–9 years 4.Canines: 9–12 years 5.Premolars: 1. First Premolars: 10–11 years 2. Second Premolars: 11–12 years 6.Second Molars: 11–13 years 7.Third Molars (Wisdom Teeth): 17–21 years Most permanent teeth have fully erupted by the early 20s, although there can be variation among individuals. Eruption Permanent teeth mnemonic Development Disturbances during Eruption 12 Premature eruption ⮚Natal teeth: premature eruption of primary (deciduous) teeth erupted into the oral cavity in infants at birth. ⮚Neonatal teeth: teeth erupting prematurely in the first 30 days of life. ⮚Etiology: Unknown Delayed eruption ⮚Etiology: ◦Systemic conditions ◦Genetic ◦Lack of nutrition ◦Hormonal disorders ◦Diseases: Down’s syndrome ◦Medications: chemotherapy ◦Other factors: prematurity, Low birth weight, tobacco smoke Multiple unerupted teeth ◦ Uncommon condition ◦ Permanent or deciduous teeth have failed to erupt ◦ Obstruction from primary teeth ◦ Bone surrounding the unerupted tooth  Embedded or impacted teeth Embedded Teeth: Unerupted teeth due to a lack of eruptive force. Impacted Teeth: Prevented from erupting by a physical barrier, such as other teeth blocking their path. Etiology: Caused by crowding, premature loss of primary teeth, or rotation of tooth during eruption. Most Frequently Impacted: Third molars and maxillary cuspids. Developmental Disturbances During Eruption ⮚Dentigerous Cyst (Follicular Cyst): ⮚Forms from the reduced enamel epithelium (REE) after the crown is fully formed and matured. ⮚Occurrence: Develops when fluid accumulates over the crown of an unerupted tooth. Dentigerous Cyst 18  Developmental Disturbances During Eruption Eruption Cyst: A type of dentigerous cyst that appears on a partially erupted tooth. Characteristics: Fluctuant, blue, vesicle-like gingival lesion. Description: A fluid-filled sac that forms in the gum tissue above a tooth shortly before it erupts. Abnormal exfoliation (loss of primary teeth) Abnormal exfoliation refers to the atypical shedding or loss of primary teeth. ⮚ Dental Anomalies: Conditions like enamel hypoplasia might cause premature loss. ⮚ Trauma: accidents or injuries to primary teeth can cause them to be lost prematurely ⮚ Untreated dental disease: severe tooth decay or untreated gum disease can lead to early tooth loss ⮚ Genetic disorders: some rare genetic disorders can affect primary tooth development and exfoliation Abnormal Occlusion (Malocclusion) 21 Occlusion Occlusion is the contact relationship between the maxillary teeth and mandibular teeth when the jaws are in a fully closed (occluded) position, as well as the relationship between the teeth in the same arch. 22 Occlusion ⮚ When teeth of either dentition are not occluding properly, the teeth and periodontium may not be able to perform the functions for which they were designed. ⮚ Unnatural occlusal stress is then placed on the dentition, which often results in occlusal disharmony. 23 MalOcclusion Occlusal disharmony may then lead to Occlusal Trauma. Etiology: ⮚ Genetic factors: malocclusion can run in families ⮚ Early loss of teeth: can lead to shifts in alignment as permanent teeth erupt. ⮚ Habits: Prolonged thumb-sucking, tongue thrusting can contribute to malocclusion 24 MalOcclusion Occlusal disharmony may then lead to Occlusal Trauma. Etiology: ⮚ Jaw size: differences in the size of the maxilla and mandible can result in overbites, underbites, or crossbites ⮚ Crowding or spacing ⮚ Dental anomalies: impacted teeth, abnormal eruption paths can also contribute to malocclusion 25 Prolong ed Thumb- sucking HABITS Occlusion ⮚Unfortunately, the effects of occlusal trauma are often irreversible, if not intercepted early enough. ⮚These occlusal disharmonies, and parafunctional habits should be controlled or eliminated during dental treatment and preventive maintenance therapy before initiating occlusal therapy. 27 10 Minutes Break  An ideal occlusion rarely exists, but the concept of a normal occlusion provides a basis for treatment. When occlusion is considered, the position of the dentition in Occlusion centric occlusion serves as the basis for reference. Thus, centric occlusion serves as the standard for describing a normal occlusion. 29 Centric Occlusion Centric Occlusion (CO) is the voluntary position of the teeth that allows maximum contact. In the CO, each tooth in one arch contacts two opposing teeth, except for the mandibular central incisors and maxillary third molars. Centric Occlusion ⮚If a tooth is lost for an extended period, neighboring teeth tend to tip into the empty space, leading to misalignment and super-eruption of the opposing tooth. ⮚This loss disrupts contact relationships in that area and can affect the occlusion of the entire dentition. 31 Tooth Loss and Centric Occlusion 32 Angle's Classification of Malocclusion Normal Overjet ⮚ In centric occlusion (CO), the maxillary arch horizontally overlaps the mandibular arch, known as overjet. ⮚A normal overjet ranges from 1 to 3 mm, providing horizontal overlap between the anterior segments of both arches. ⮚This allows for increased range of motion of the mandible and helps keep soft tissue out of the way during mastication. Overjet Overjet is measured in millimeters with the tip of a periodontal probe, once a patient is in centric occlusion. The probe is placed at a right angle to the labial surface of a mandibular incisor at the base of the incisal edge of a maxillary incisor. Normal Overbite In centric occlusion, the maxillary arch also vertically overlaps the mandibular arch, a position called Overbite. Overbite is measured in millimeters with the tip of a periodontal probe after a patient is placed in CO. The probe is placed on the incisal edge of the maxillary incisor at right angles to the mandibular incisor.  Healthy Vs Unhealthy Overbite normal amount of vertical overlap, normally 2 to 5 mm, between the anterior segment of the two arches allows contact between the posterior teeth during mastication. Excessive amounts of either overjet or overbite are classified as Malocclusions. 37 Underbite When the reverse is the case, and the mandibular arch extends forward beyond the maxillary arch, the condition is referred to as an Underbite (or retrognathia). Contacts Within each dental arch, the teeth also create contact areas as they contact their same arch neighbors on their proximal surfaces; the exception is the last tooth in each arch of each dentition, which lacks a distal contact. This contact between neighboring teeth serves two purposes: ◦ it protects the interdental papillae ◦ stabilizes each tooth in the dental arch. 39 Contacts Open contacts allow areas of food impaction from opposing cusps, called plunging cusps, resulting in trauma to the interdental gingiva. Open contacts also do not allow mesiodistal stability between the teeth. Passive Eruption Gradual recession of the gingiva and the underlying alveolar bone Tooth doesn’t actually move, soft tissue ‘shrinks’ away. Post-eruptive – Occlusion – PDL Health Malocclusions can have several effects: ◦ Lead to poor home care (increased chance of Periodontal disease) ◦ Negative impact on appearance Most malocclusions can be treated ◦ 80% of Teenagers show some form of malocclusion ◦ Crowding ◦ Overjet 42