Ortho - Hypodontia (A) Flashcards
Define hypodontia.
Congenital absence of one or more teeth
Define anodontia
Complete absence of teeth
Define severe hypodontia
6 or more congenitally absent teeth
What teeth are most affected by hypodontia? (5)
(8’s), Lower 5’s, Upper 2’s, Upper 5’s, lower incisors
What are congenitally missing upper laterals usually associated with?
ectopic canines
List some syndromic causes of hypodontia? (2)
> 100 craniofacial syndromes are associated with hypodontia;
* Cleft lip and palate commonly associated
* Anhydrotic etodermal dysplasia
What causes non-syndromic hypodontia? (3)
– Mutations in at least 3 genes
– Familial link/genetic tendency (not always the case)
– Sporadic
How does hypodontia present clincically? (5)
- 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
What are the problems associated with hypodontia? (10)
- 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)
What is the most common dental problem assoicated with hypodontia?
Microdontia
what are the problems associated with severe hypodontia (6 or more missing)? (5)
- Spacing
- Drifting
- Over-eruption
- Aesthetic impairment
- Functional problems
How do we manage a px with hypodontia? (2)
- Starts with recognition by GDP
- 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
How would we manage a young patient with hypodontia affecting the 12 & 22 with ectopic/unerupted canines. (4)
– referral to specialist
- Extraction URb, ULb – allow 3’s to erupt
- Sectional fixed appliance to close space between UR1, UL1
= Allows eruption UR3, UL3 - Retainers put behind upper teeth to prevent relapse
What special investigation are required for a hypodontia patient?
- 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)
What is a TAD and what is its function?
TAD – mini bone screw (looks like a nail screwed into the bone)
Used for: anchorage
What are the tx options for a patient with hypotonia affecting the 12&22? (4)
- Accept
- Restorative tx alone (open space tx)
- Orthodontics tx alone (close space tx)
- Combined orthodontic & restorative treatment (space closure plus)
Describe the open space tx options for a patient with congenitally missing upper laterals. (5)
Resin bonded bridge
Implant
RPD
Conventional bridge
autotransplantation
What criteria must treatment for hypodontia satisfy? (3)
- Satisfies px’s expected aesthetic objectives
- Least invasive option possible
- Satisfies expected functional objectives;
– Immediate
and
– Long term (65 years +)
What tooth is the ideal abutment for a RBB and why? (3)
Canine
- Large root length
- Good crown dimensions
- less shine through
What are the advantages of using RBB’s to replace missing upper laterals? (5)
- 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)
What are the disadvantages of using RBB’s to replace missing upper laterals? (3)
- Failure rate
- Appearance sometimes not ideal
- Orthodontic retention needs are high
How much space is required for implant placement?
7mm (¶llell)
Why do we use CBCT for implant planning? (3)
Allows more accurate assessment of;
- Root positions
- Bone width
- Bone volume
In close space/restorative tx only, why would we opt to use a RBB rather than an implant to replace missing upper laterals? (7)
- 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
What must we consider when using a space closure + method to replace missing upper lateral incisors? (3)
- Tooth shape/size
- Tooth colour
- Gingival architecture/ margin levels
What are the advantages of using a space closure + method to replace missing upper laterals? (3)
- No prosthesis required – relatively low maintenance
- Good aesthetics with appropriate orthodontic and restorative techniques
- Can be done at an early age
