Orthodontics-Hypodontia

1. Hypodontia
@nhalhamlan
@saudibraces
nasiralhamlan
@nasiralhamlan
Dr.Nasir Alhamlan
Saudi Arabia

2. Hypodontia describes a situation where the patient
is missing up to 6 teeth, excluding the 3rd molars.
The term Hypodontia is generally used to describe developmental tooth absence
excluding the third molars (Goodman et al., 1994).
Hypodontia may be sub-classified according to its severity, as mild (1–2 missing teeth)
almost 80%, moderate (3–5 missing teeth almost 10%) or severe (≥6 missing teeth
almost 1%). (Larmour 2005, Naini et al., 2011)

3. A. According to the number of teeth involved (Goodman et.al., 1994).
1.Hypodontia refers to a lack of 1-6 teeth, excluding third molars
2. Oligodontia (sever hypodontia) refers to a lack of more than six teeth,
excluding third molars Hobkirk et al., 1995
3. Anodontia refers to a complete absence of teeth in one or both dentitions.
Very rare.
Classification

4. B. According to the inheritance pattern (Wright et.al., 1993).
1. Non-syndromic hypodontia
A. Non-syndromic hypodontia can be sub-classified according to method of
occurrences (Burzynski and Escobar, 1983):
- Familial or Inherited. This form can follow autosomal dominant,
autosomal recessive or autosomal sex-linked patterns of inheritance,
with considerable variation in both penetrance and expressivity.
- Sporadically 33% of hypodontia cases
Classification

5. B. Non-syndromic Hypodontia can be sub-classified according to teeth
involved and their number:
1.Localized incisor–premolar hypodontia (OMIM 106600), which affects only
one or a few of these teeth. This is the most common form and is seen in around
8% of Caucasians (Nieminen et al, 1995).
2. Oligodontia (OMIM 604625) occurs in around 0.25% of Caucasians and can
involve all classes of teeth (Sarnas & Rune, 1983).
C. Candidate genes for non-syndromic human hypodontia (Vastardis et al.,
1996; Lammi et al., 2004; Suda et al., 201, Cobourne, 2007, Han et al., 2008):
• MSX1 associated with premolar and lateral incisors. Usually associated with
sever hypodontia.
• EDA gene mutations usually includes the loss of mandibular and/or maxillary
incisors and canines
• PAX9. Associated with molars.
• AXIN2 which is mainly associated with Finnish family hypodontia.
Classification

6. Classification
2. Syndromic Hypodontia
• Seen in association with Down syndrome, ectodermal dysplasia, CCDS, CLP
& CP , Van de Wound syndrome, Rieger and Book syndrome. Larmour
2005, Shapira et al., 2000), (Kerwetzki and Homever, 1974; Marković,
1982b; Parsche et al., 1990), (Uthoff, 1989).
• Candidate genes MSX1 (MSX1 represents a candidate gene for both
syndromic and nonsydromic hypodontia).

7. • F:M = 3:2
* As a general rule, if only one or a few teeth are missing, the absent tooth will be
the most distal tooth of any given type (Jorgenson, 1980; Schalk van der Weide et al.,
1994).
• Lower > Upper

8. Teeth affected:
- 25-35% of all third molars
- Lower premolars most commonly absent and mainly symmetrical (2.6%)
Missing laterals: 2% More bilaterally than unilaterally. Familial tendency
associated with peg contralateral laterals incisors and palatally impacted
canines. It represents 20% of the hypodontia cases (Bren et al).
- Lower incisor 0.2% of Caucasians but more common in Asian.
- U3s developmentally absent 3's: 0.08% (Bren et al)
- First and second molars, is rare (Simons et al, 1993).
- The overall prevalence of peg-shaped maxillary permanent lateral incisors was
1.8%. he prevalence rates were higher among Mongoloid people, orthodontic
patients, and women. Although the prevalence of unilateral and bilateral lateral
incisors was the same, the left side was twice as common as the right side.
Subjects with unilateral peg-shaped maxillary permanent lateral incisors might
have a 55% chance of having lateral incisor hypodontia on the contralateral
side.

9. 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
If primary tooth missing - can't have permanent tooth

11. Clinical Features
• More common in Mongoloid than whites
• Associated features include microdontia, reduced
alveolar development, increased freeway space
and retained primary teeth
• Absence may be unilateral or bilateral
• Commonly missing are third molar, maxillary lateral
incisor, maxillary and mandibular second premolar

13. Why we treat Hypodontia?
For Aesthetic and Functional and Durable Dentition.
- People have high expectations of dentistry in general,
- People have high aesthetic expectations.

14. • Management of Hypodontia
Multidisciplinary team for hypodontia treatment:
1. Clinical Nurse Coordinator
2. Orthodontist
3. Restorative Dentist
4. Pedodontist
5. Prosthodontist
6. Oral Surgeon
7. General dental practitioner

15. Indications for Treatment
• Aesthetics
• Functional
• Dental rehabilitation
• Dental health problems
• Food impaction due to tipped or drifted teeth
• Traumatic OB
• Infraoccluded primary teeth

16. Factors to be considered in the management of Hypodontia
• Age: Younger preferred because OB can be corrected and stability better,
also PD problem and caries become an issue in adult
• Severity As the number of absent teeth increases the treatment option of
space closure becomes unrealistic.
• Facial profile
• Intra-arch relationship (crowding or spacing)
• Inter-arch relationship (dynamic and static relationship)
• Shape, size and colour of the adjacent teeth
• Smile and gingival line
• Clinical situation of the primary and permanent teeth
• Patient's opinion and co-operation
• Clinician philosophy

17. Available options
· Space closure
· Space opening
· Do nothing

18. Available options - Space Closure
· No prosthesis necessary
· Result dictated by:
Tooth size,
Colour,
Positioning,
Emergence profile,
Available restorative technique and materials

19. Available options - Space Opening
· Symmetry and pre-existing good intercuspation may be easier
to maintain.
· Prosthesis required (unless Transplanting or Implanting)

20. Available options - Do Nothing
· Has advantage of simplicity
· Aesthetics may be compromised
· Prosthesis may be required later (and this may be difficult or
impossible)

21. Opening spaces
· Check spacing, if necessary use a wax-up
· Check static occlusion
· Check dynamic occlusion
· Watch for unaesthetic rotations
· Retain adequately prior to restoration

22. THANK YOU