Ortho - Hypodontia (A)

Question 1

Define hypodontia.

Answer 1

Congenital absence of one or more teeth

Question 2

Define anodontia

Answer 2

Complete absence of teeth

Question 3

Define severe hypodontia

Answer 3

6 or more congenitally absent teeth

Question 4

What teeth are most affected by hypodontia? (5)

Answer 4

(8’s), Lower 5’s, Upper 2’s, Upper 5’s, lower incisors

Question 5

What are congenitally missing upper laterals usually associated with?

Answer 5

ectopic canines

Question 6

List some syndromic causes of hypodontia? (2)

Answer 6

> 100 craniofacial syndromes are associated with hypodontia;
* Cleft lip and palate commonly associated
* Anhydrotic etodermal dysplasia

Question 7

What causes non-syndromic hypodontia? (3)

Answer 7

– Mutations in at least 3 genes

– Familial link/genetic tendency (not always the case)

– Sporadic

Question 8

How does hypodontia present clincically? (5)

Answer 8

• Early on in life
• Delayed or asymmetric eruption
• Retained or infra-occluded deciduous teeth
• Absent deciduous tooth = guaranteed absence of permanent
• Tooth form = tapered and small teeth

Question 9

What are the problems associated with hypodontia? (10)

Answer 9

• Microdontia (most common)
• Malformation of other teeth (unusual crown forms)
• Short root anomaly
• Impaction
• Delayed formation and/or delayed eruption other teeth (delayed development)
• Crowding and/or malposition of other teeth
• Maxillary canine/first premolar transposition
• Taurodontism
• Enamel hypoplasia
• Altered craniofacial growth (with a syndromic component)

Question 10

What is the most common dental problem assoicated with hypodontia?

Answer 10

Microdontia

Question 11

what are the problems associated with severe hypodontia (6 or more missing)? (5)

Answer 11

• Spacing
• Drifting
• Over-eruption
• Aesthetic impairment
• Functional problems

Question 12

How do we manage a px with hypodontia? (2)

Answer 12

1. Starts with recognition by GDP
2. Appropriate ortho referral/GHD referral
   - GDH specifically if a multidisciplinary approach is required (ortho and restorative)
   - Initial assessment in Orthodontics and allocate when appropriate to Hypodontia Clinic

Question 13

How would we manage a young patient with hypodontia affecting the 12 & 22 with ectopic/unerupted canines. (4)

Answer 13

– referral to specialist

1. Extraction URb, ULb – allow 3’s to erupt
2. Sectional fixed appliance to close space between UR1, UL1
   = Allows eruption UR3, UL3
3. Retainers put behind upper teeth to prevent relapse

Question 14

What special investigation are required for a hypodontia patient?

Answer 14

• Study Models
• Diagnostic wax up – planning for ortho-restorative treatment
• Planning models - Kesling, diagnostic
• Radiographs - OPT
• Photographs
• Cone beam CT - Assess bone volumes (implant planning at a later stage)

Question 15

What is a TAD and what is its function?

Answer 15

TAD – mini bone screw (looks like a nail screwed into the bone)
Used for: anchorage

Question 16

What are the tx options for a patient with hypotonia affecting the 12&22? (4)

Answer 16

• Accept
• Restorative tx alone (open space tx)
• Orthodontics tx alone (close space tx)
• Combined orthodontic & restorative treatment (space closure plus)

Question 17

Describe the open space tx options for a patient with congenitally missing upper laterals. (5)

Answer 17

Resin bonded bridge
Implant
RPD
Conventional bridge
autotransplantation

Question 18

What criteria must treatment for hypodontia satisfy? (3)

Answer 18

1. Satisfies px’s expected aesthetic objectives
2. Least invasive option possible
3. Satisfies expected functional objectives;
   – Immediate
   and
   – Long term (65 years +)

Question 19

What tooth is the ideal abutment for a RBB and why? (3)

Answer 19

Canine
- Large root length
- Good crown dimensions
- less shine through

Question 20

What are the advantages of using RBB’s to replace missing upper laterals? (5)

Answer 20

• Relatively simple
• Do when young (complete treatment)
• Non-destructive (minimal enamel prep)
• Good aesthetics
• Place on semi-permanent basis (not definitive tx however used until px completes growth or whilst other tx being carried out)

Question 21

What are the disadvantages of using RBB’s to replace missing upper laterals? (3)

Answer 21

• Failure rate
• Appearance sometimes not ideal
• Orthodontic retention needs are high

Question 22

How much space is required for implant placement?

Answer 22

7mm (&parallell)

Question 23

Why do we use CBCT for implant planning? (3)

Answer 23

Allows more accurate assessment of;
- Root positions
- Bone width
- Bone volume

Question 24

In close space/restorative tx only, why would we opt to use a RBB rather than an implant to replace missing upper laterals? (7)

Answer 24

• Can’t do implant till about 18-19 (or later?)
• Need a minimum 7mm space = difficult to achieve
• Root separation required = difficult to achieve
• Often need bone graft
• Technically very demanding in aesthetic zone
• Takes a significant extra time to do implant planning
• Significant cost of implants – esp In upkeep

Question 25

What must we consider when using a space closure + method to replace missing upper lateral incisors? (3)

Answer 25

• Tooth shape/size
• Tooth colour
• Gingival architecture/ margin levels

Question 26

What are the advantages of using a space closure + method to replace missing upper laterals? (3)

Answer 26

• No prosthesis required – relatively low maintenance
• Good aesthetics with appropriate orthodontic and restorative techniques
• Can be done at an early age