Incisors are the first erupting teeth in both the Deciduous and permanent dentition. There are four Incisors in the Maxillary arch and four Incisors in the Mandibular arch in both deciduous and permanent dentition. The Deciduous Mandibular Central Incisors are the First Teeth to erupt into the oral cavity at an Age of 6 – 10 months and the Permanent First Molars (upper and lower) are the first permanent teeth to erupt at an age of 6-7 years into the oral cavity.
There are 2 Central Incisors in Maxillary arch and 2 in Mandibular arch, 2 Lateral Incisors in Maxillary and 2 Lateral Incisors in Mandibular arch in Deciduous and Permanent Dentition. These account to total of 8 Incisors in both dentition.
17 main Differences between Maxillary and Mandibular Incisors:
Maxillary Incisors are larger than Mandibular Incisors.
- Maxillary incisors have wider Mesio-Distal diameter than Labio-Lingual Diameter.
- Mandibular Incisors have wider Labio-lingual Diameter than Mesio-Distal diameter.
- Maxillary Incisors have more distinct lingual Anatomy.
- Maxillary incisors have lingual pits not found on Mandibular incisors.
- Maxilary incisors have rounded roots on cross-section.
- All incisors except the Mandibular Central Incisor have Rounded Disto Incisal angle compared to the Mesioincisal Angles – Because Mandibular Central incisor is Symmetrical.
- In Mandibular incisors, Incisal edge is lingual to labiolingual midpoint.
- Maxillary Incisors Incisal edge is centered Labiolingually
- Facial Embrasure is greater than Lingual Embrasure in Mandibular Incisor.
- Lingual Embrasure is greater than Facial Embrasure in Maxillary Incisor.
- Height of Contour is more incisal on Mandibular Incisor.
- Mandibular Incisors Labial surface is straighter and Flatter than Maxillary Incisors.
- Smallest Tooth- Mandibular Central Incisor
- Bilaterally Symmetric Tooth- Mandibular Central Incisor
- Most distinct Lingual Anatomy – Maxillary Lateral Incisor.
- Incisal Edge is not Perpendicular to Labio-Lingual Bisecting Linein – Mandibular Lateral Incisor
Eruption and Exfoliation Age of Deciduous and Permanent Incisors in Oral Cavity:
- Maxillary Centrals Incisors: Erupt at 8-12 months and Exfoliate at 6-7 years
- Mandibular Central Incisors: Erupt at 6-10 months and Exfoliate at 6-7 years
- Maxillary Lateral Incisors: Erupt at 9-13 months and Exfoliate at 7-8 years
- Mandibular Lateral Incisors: Erupt at 10-16 months and Exfoliate at 7-8 years
- Maxillary Centrals Incisors: Erupt at 7-8 years
- Mandibular Central Incisors: Erupt at 7-8 years
- Maxillary Lateral Incisors: Erupt at 8-9 years
- Mandibular Lateral Incisors: Erupt at 8-9 years
Knowing the Differences in Anatomy of Incisors is important as it helps in Restorations and to get the perfect shape of the teeth as these are the first visible teeth when a person talks of smiles.