Aetiology of Malocclusion 2 - Local Causes of Malocclusion Flashcards
What is the prevalence of malocclusion in population?
- 68% Malocclusion
- 32% Normal occlusion
What are the local causes of malocclusion?
- Variation in tooth number
- Variation in tooth size or form
- Abnormalities of tooth position
- Local abnormalities of soft tissues
- Local pathology
What is included in variation in tooth number for local cause of malocclusion?
- Supernumerary teeth (extra)
- Hypodontia (developmentally absent teeth)
- Retained primary teeth
- Early loss of primary teeth
- Unscheduled loss of permanent teeth
What are supernumerary teeth and their prevalence?
- Tooth or tooth-like entity which is additional to the normal series
- Most commonly in anterior maxilla
- males > females
Prevalence: - 1% in primary dentition
- 2% in permanent dentition
What are the types of supernumerary teeth?
- Conical
- Tuberculate
- Supplemental
- Odontome
What are conical supernumerary teeth?
- Small peg shaped
- Close to midline
- May erupt (Extract)
- Usually 1 or 2 in number
- Tend to not prevent eruption but may displace adjacent teeth
What are tuberculate supernumerary teeth?
- Tend not to erupt
- Paired
- Barrel-shaped
- Usually extracted
- One of the main causes of failure of eruption of permanent upper incisors
What are supplemental supernumerary teeth?
- Extra teeth of normal morphology
- Most often upper laterals or lower incisors
- Can be third premolars, fourth molars
- Often extract - decision based on form and position
What are the two types of odontome supernumerary teeth?
Compound - discreet denticles
Complex - disorganised mass of dentine, pulp and enamel
What is hypodontia and its prevalence?
- Developmental absence of one or more teeth
- Females > males 3:2
- 4-6% population (excluding 8’s)
- Commonly upper laterals (2s) > second premolars (5s)
What are retained primary teeth?
- Disruption in sequence of eruption
- A difference of more than 6 months between the shedding of contra-lateral teeth (Alarm bells)
Why are primary teeth retained?
- Absent successor
- Ectopic successor or dilacerated
- Infra-occluded (ankylosed) primary molars
- Dentally delayed in terms of development
- Pathology / supernumerary
What to do if there is an absent successor in primary teeth retention?
- Either maintain primary tooth as long as possible
(if good prognosis) - Or, extract deciduous tooth early to encourage
spontaneous space closure in crowded cases - Early orthodontic referral for advice
What are infra-occluded primary molars?
- Process where tooth fails to achieve or maintain its occlusal relationship with adjacent teeth
- AKA submerged
- Temporary ankylosis
- Common 1-9%
- Gives percussion sound
What are the 3 severity levels of infra-occluded primary molars?
Slight - Between occlusal surface and interproximal contact, less than 2mm
Moderate - Within occluso-gingival margins of interproximal contact
Sever - Below interproximal contact point
What can cause early loss of primary teeth?
- Trauma
- Periapical pathology
- Caries
- Resorption by successor
What does early loss of primary teeth depend on?
- Which tooth is extracted
- When tooth is extracted
- Patient’s inherent crowding
Lead to localisation of crowding
What is balancing extraction?
- Extraction of tooth from opposite side of same arch
- Designed to minimise midline shift
What is compensating extraction?
- Extraction of tooth from opposing arch on same side
- Designed to maintain occlusal relationhip
How does early loss of incisors impact the dentition and treatment?
- Very little impact
- No compensating or balancing extraction
How does early loss of canines impact dentition and treatment?
- Unilateral loss in crowded arch, can give centre-line shift
- Will get some mesial drift of buccal segments
- Consider balancing extraction
How does early loss of molars impact dentition and treatment?
- More space loss with E’s > D’s
- More space loss in upper > lower
- 6’s drift mesially and steal 5 space
How does extraction timing of primary teeth affect dentition?
- Most effect when primary teeth extracted early
- Little effect if extracted late
How does inherent crowding affect early loss of primary teeth?
- Marker space loss in crowded patients
- Minimal or no space loss in spaced dentitions
When should you assess 6’s prognosis?
- Routine assessment of 6’s prognosis dental age 8-9 years.
What factors influence impact of the loss of 6s?
- Age at loss
- Crowding
- Malocclusion
How does age at loss of 6s affect dentition?
Upper arch - less important
Lower arch - If 7s erupted (late) often poor space closure, If too early distal drift of 5s particularly if Es lost at same time as 6s
How does crowding affect dentition with loss of 6s?
Upper arch - potential for rapid space loss
Lower arch
- If spaced then will have spaces
- If aligned then will have spaces
- If crowded then best results likely
How does timing effect dentition with unscheduled loss of central incisors?
- Early loss will result in drift of adjacent teeth
- Late loss will result in long term space
What to do with unscheduled loss of central incisors?
- Ideally maintain space by re implant or simple denture
- Plan how to deal with space longer term i.e definitive prosthesis
- If lateral incisor drifts to fill space then build up lateral or re-open space for prothesis
What are the different variations in tooth size or form?
Too large - macrodontia
Too small - microdontia
Abnormal form
What is macrodontia?
- Tooth/teeth larger than average
- Can be localised or generalised
Problems - Crowding
- Asymmetry
- Aesthetics
What is microdontia?
- Tooth/teeth smaller than average
- Can be localised or generalised
- Leads to spacing
- Linked to hypodontia
What are abnormal forms of teeth?
- Peg shaped laterals
- Dens in dente
- Geminated/fused teeth
- Talon cusps
- Dilaceration
- Accessory cusps and ridges
What are most common ectopic teeth?
- Can be any tooth but most commonly
- Third molars (8s)
- Upper canines (3s)
- First permanent molars (6s)
- Upper centrals (1s)
What are transpositions?
- Unique and severe condition of ectopic eruption
- Defined as interchange in position of two permanent adjacent teeth located at same quadrant in dental arch
What is the prevalence of ectopic maxillary canines?
- 1-3% population
- 80% palatal
Check for palpable buccal canine bulge from 9years onwards
- Further investigation or refer if in doubt
What is included in clinical assessment of ectopic canines?
- Visualisation/palpation of any obvious bumps of 3
- Inclination of 2
- Mobility of c or 2
- Colour of c or 2
What is included in radiographic assessment of ectopic canines?
- 2 radiographs needed to localise position
(usually OPT and upper anterior oblique occlusal) - Use parallax technique
3 Ps = Presence, Position, Pathology
What are the management options for ectopic canines?
1.Prevention
2. Extraction c to encourage improvement in position of 3 (interceptive)
3. Retain 3 and observe (accept its position)
4. Surgical exposure and orthodontic alignment
5. (Surgical) Extraction
6. Autotransplantion
What is included for prevention of ectopic canines?
- Appropriate monitoring from age 9 onwards.
- Clinical assessment
- Symmetry
What are ectopic first molars a sign of?
- Crowding (greater in CLP)
- Mesial path of eruption
- Abnormal morphology of E
How to manage ectopic first molars?
- Separator
- Attempt distalise 6
- Extract E
Prevalence of ectopic first molars?
- Less than 5%
- More commonly U arch
- Reversible before age 8
- Caries risk
What are potential causes of ectopic upper central incisors?
- No obvious cause
- Supernumerary (Tuberculate or odontome)
Trauma to primary predecessor
- Ankylosis of primary tooth
- Displacement of tooth germ
- Dilaceration of root
What is the classification of Transpositions?
- True/ Pseudo
Most common - Upper canines and first premolar
- Lower canines and incisors
Treatment options for transposition?
- Accept
- Extract
- Correct
What are some local abnormalities of soft tissues?
- Digit sucking
- Fraenum
- Tongue thrust
What can non-nutritional digit sucking habit cause?
- Proclined UI
- Retroclined LI
- Anterior open bite
- Unilateral posterior crossbite
- Due to narrow maxillary arch
- May cause mandibular displacement
What local abnormality can the labial fraenum cause?
- May cause median diastema
What are the three forms of local pathology?
- Caries
- Cysts
- Tumours
Definition of ectopic tooth?
- Tooth that is not located in dental arch due to faulty course during eruption
