1. Introduction to Oral & Dental Anatomy and Morphology 16
Dr Jamal Naim
PhD in Orthodontics
Dental Anomalies

2. Introduction
Dental anomalies are disturbances in tooth development determined by:
genetic factors (inherited) and/or
environmental factors (acquired).
Number, size, shape alterations as well as defects of mineralized tissues and eruptional problems are the most common dental anomalies reported.

3. Introduction
These few facts about tooth development will assist us in understanding tooth anomalies:
Teeth form from the cooperative interaction of two germ layers: ectoderm and ectomesenchyme
Enamel is formed from the ectodermal components.
Dentin, pulp, cementum, the supporting PDL, and bone are all derived from ectomesenchyme.

4. Introduction Very few heritable dental traits are truly Mendelian.
Most dental variations are polygenic, that is controlled by several genes. With these, we often speak of the degree of expression or penetrance.
Individually, anomalies are rare but collectively they form a body of knowledge with which all dentists should be familiar.

5. Eruptional problems
Ectopic Eruption is a developmental disturbance in the eruption of the permanent dentition (in direction).
The affected tooth is out of normal alignment and causes sometimes abnormal resorption of another neighboring primary/permanent tooth (undermining resorption).

6. Eruptional problems The most commonly ectopic erupted teeth are:
the permanent maxillary first molars,
the maxillary canines, and
the permanent mandibular lateral incisors.

7. Ectopic erupted upper molar Ectopic erupted lower centrals
Eruptional problems
Ectopic erupted upper molar
Ectopic erupted lower centrals

8. Ectopic erupted upper centrals, labially
Eruptional problems
Ectopic erupted upper centrals, labially

9. Eruptional problems
Impacted teeth are those that have failed to erupt and remain buried in the alveolar bone. Usually, some barrier to eruption will be seen on the X-ray film.
The third molars and maxillary canine are the most frequently impacted teeth, followed by premolars and supernumerary teeth.

10. Impacted second premolar
Eruptional problems
Impacted second premolar
Impacted second molar

11. Upper central palatally impacted Impaction of upper canine
Eruptional problems
Upper central palatally impacted
Impaction of upper canine

12. Anomalies in Tooth Eruption
An iatrogenic disease or condition is one that is 'doctor-caused'.
If a second molar is inadvertently impacted by a poorly placed molar band, it is an iatrogenic cause for impaction.

13. Anomalies in Tooth Eruption
Treatment of ectopic eruption:
Self-corrective: 66% of the ectopically erupted molars finally erupted into an acceptable position without corrective treatment (Young, 1957).
Treatment with eruptive guidance (ortho):
After Extraction of the primary second molar; the permanent molar is allowed to erupt and then distalized to a normal position.

14. Anomalies in Number of Teeth
Hyperdontia
Hypodontian

15. Anomalies in Number of Teeth
Hyperdontia (or supernumerary teeth ) is defined as an increase in the number of teeth in a given individual, i.e., more than 20 deciduous teeth, and over 32 teeth in the case of the permanent dentition.

16. Anomalies in Number of Teeth
Regarding the etiology of supernumerary teeth, most authors point to phylogenetic factors, specifically hyperactivity within the dental lamina, causing the appearance of additional dental buds.
Supernumerary teeth may occur singly, multiply, unilaterally or bilaterally and in one or both jaws. Rarely it can occur in all the four quadrants of the jawbone.

17. Anomalies in Number of Teeth
Effects of hyperdontia on the developing dentition may be:
crowding,
delayed eruption of adjacent permanent teeth,
displacement and ectopic eruption,
formation of diastema,
root resorption of adjacent dentition and loss of vitality,
dilaceration of adjacent dentition
follicular cysts

18. Hyperdontia Incidence: About 2.0 % in primary dentition
About 4.0 % in permanent dentition
Males : Females = 2:1
Often in the maxilla (80% -90 %)
Most common supernumerary tooth is mesiodens

19. Hyperdontia In primary Dentition:
Most common supernumerary teeth in the primary dentition are upper laterals and canines.
Shape is the natural teeth like.
Most of them erupt normally.

20. Hyperdontia In permanent Dentition:
6 -9 time more in the maxilla (incisor and molar region) than in the mandible (premolar region)
Most smaller than normal teeth
Most irregular shape than normal teeth

21. Hyperdontia

22. Mesiodens Majority occur with familial instances.
About 0.2 % - 1% of all adults
45 – 67 % of all supernumerary teeth
Often impacted (75%)
are cones shaped
have short roots
around the midline at the palatal side.

23. Disto- and paramolars “distomolar” erupt distally to the third molar
Small molars distal the third molar (M4 & M5)
If localized buccal of the molars, then paramolars
Have often 1 root and cones shaped crowns
Distomolar or M4

24. Supplementary PM and canine
Supplementary canines always in the maxilla
Supplementary premolars always in the mandible
Often lingual and about 6-10 years delay of development
Often they stay impacted
Often traumatic history about the 9-12 year of age
Supplementary PM

25. Hyperdontia Hyperdontia is always associated with:
Cleft Lip and Palate
Cleidocranial Dysplasia
Gardner's Syndrome
Down's Syndrome (Trisomy 21)
Crouzon's Syndrome (Craniofacial Dysostosis)

26. Cleidocranial Dysplasia

27. Hypodontia Hypodontia (congenital tooth absence):
Most common etiology is hereditary
Incidence = 0.4 – 0.9 % in primary Dentition
Most common:
upper lateral incisors
Lower incisors
Often successor permanent is also missed

28. Hypodontia
Incidence = % in permanent Dentition, excluding third molars
Most common: > > 5 5 > 2 2
About % of 3. Molar are missed.

29. Anomalies in Number of Teeth
Hypodontia: the absence of one or a few teeth
Oligodontia: Agenesis of numerous teeth
Anodontia: Extreme expression of oligodontia, indicating complete absence of teeth

30. Anomalies in Number of Teeth
Hypodontia/ missed 2. PM

31. Anomalies in Number of Teeth
Hypodontia/ missed primary laterals
Hypodontia/ missed permanent laterals

32. Anomalies in Number of Teeth
Oligodontia

33. Hypodontia Syndromes Associated with Hypodontia: Cleft lip and palate
Ectodermal Dysplasia
Incidence: 1:100,000 births