local causes of malocclusion Flashcards
prevalence of malocclusion
68% malocclusion
32% noraml occlusion
4 categories of causes of malocclusion
- skeletal
- class III
- high FMPA
- dental
- missing teeth
- soft tissue
- lip trap
- other
- habits
local causes of malocclusion
a localised problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion
- Tend to get worse with time
- Scope for interceptive treatment
- Good to recognise
categories of local causes of maloccusion (5)
- Variation in tooth number
- Variation in tooth size or form
- Abnormalities of tooth position
- Local abnormalities of soft tissue
- Local pathology
5 causes of variation in toothnumber
- Supernumerary teeth (extra)
- Hypodontia (developmentally absent teeth)
- Early loss of primary teeth
- Retained primary teeth
- Unscheduled loss of permanent teeth
3-5 are variations in timing of teeth present
supernumarary teeth
a tooth or tooth a tooth or tooth-like entity 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
4 types of supernumarary teeth
- Conical
- Tuberculate
- Supplemental
- Odontome
conical supernumerary
- Small, peg shaped
- close to midline = mesiodens
- may erupt (extract)
- usually 1 or 2 in number
- tend not to prevent eruption but
- may displace adjacent teeth
tuberculate supernumaries
- tend not to erupt,
- paired
- barrel-shaped
- usually extracted
- one of the main causes of failure of eruption of permanent upper incisors
supplemental supranumeraries
- extra teeth of normal morphology
- most often upper laterals or lower incisors
- can be third premolars, fourth molars often extract
- cause crowding, centre-line shift etc – impeding space of other teeth
- often extract - decision based on form and position (keep better)
here 13, 12, 11,21, 22, extra 22, 23
odontome supernumeraries
types
- Compound
- discreet denticles
- Complex
- disorganised mass of dentine, pulp and enamel
here 21, 22, 63 with 23 above but in between mass of structure impeding eruption and displaced 24
odontome management
refer to orthodontics and oral surgery – investigate, remove obstruction to allow further eruption of permanent teeth
whats odd here
Lower incisors present
12, 51, 61, 22
- Sequence of eruption is incorrect -> investigate
Radiographs – can see 51 and 61 with 11 and 21 above but in between there’s other opacities = supernumerary teeth
- (refer to oral surgery – remove obstructions allowing incisors to erupt)
hypodontia
- developmentally absence of one or more teeth
occurence of hypodontia
- Females > males 3:2
- 4-6% population (excluding 8’s)
- commonly upper laterals (2s) > second premolars (5s)
- mild, moderate and severe depending on how many teeth are missing
retained primary teeth
malocclusion cause
- A disruption in the sequence of eruption
A difference of difference of more than 6 months between the shedding of contra shedding of contra-lateral lateral teeth.
- Alarm bells
5 reasons primary teeth may be retained
- Absent successor
- nothing to resorb primary tooth out due to hypodontia of permanent
- Ectopic successor or dilacerated /impacted
- Infra-occluded (ankylosed) primary molars
- Dentally delayed in terms of development
- Pathology/supernumerary
how to deal with retained primary tooth when absent successor
- 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
how to deal with retained primary canine here
- clinical and radiographic investigations to see what is happening to permanent canine
- On periapical can see 13 is present and it is nearly in line but the deciduous canine is impeding its eruption into its proper place
- Need deciduous extracted (interceptive extraction) allow spontaneous eruption of permanent canine
infra-occluded primary molars falsely referred to as
submerged molars
incorrect
infra-occluded primary molars
process where a tooth fails to achieve or maintain its occlusal relationship with adjacent teeth
- temporary ankylosis
- Common 1-9%*
Different percussion sound
Look like they are sinking because they stay where they are and the rest of the teeth around them continue to develop and grow – everything moving around it whilst it stays still
grades for infraoccluded primary molars
Slight
- between occlusal surface and interproximal contact - less than 2mm
Moderate
- within occluso-gingival margins of interproximal contact
Severe
- below interproximal contact point
Moderate and severe – refer to specialist and consider extraction of deciduous infra-occluded tooth/teeth
management of infra-occluded primary molars
- permanent successor present
- Usually self-correct so keep under review.
- Consider extraction if:
- contact points are going subgingival
- root formation of the successor is near completion
- permanent successor absent
- Depends on potential of crowding:
- Retain if in good condition (onlay)
- Or extract and plan space management (orthodontics)
- Depends on potential of crowding:
4 reasond for early loss of primary teeth
- Trauma
- Periapical pathology
- Caries
- Resorption by successor
localisation of crowding
depends on
- Which tooth is extracted
- When the tooth is extracted
- Patient’s inherent crowding
balancing extraction
- By extraction of a tooth from the opposite side of the same arch
- Designed to minimise midline shift.
compensating extraction
- By extraction of a tooth from the opposing arch of the same side
- Designed to minimise maintain occlusal relationship
which primary teeth tend to be lost early
Incisors
- Very little impact
- No compensating or balancing ext
Canines
- unilateral loss in crowded arch, can give centre-line shift
- will get some mesial drift of buccal segments
- consider balancing extraction
- e.g. lose upper right, extract upper left to keep centre-line
molars
- more space loss with E’s > D’s
- more space loss in upper > lower
- 6’s drift mesially and steal 5 space
- Impede 5 eruption
- Look to space maintain tend not to balance or compensate
Get second opionion if unsure
when to do extractions
- most effect when primary teeth extracted early
- little effect if extracted late
inherent crowding
- marked space loss in crowded patients
- minimal or no space loss in spaced dentition
uscheduled loss of 6s
- Routine assessment of 6’s prognosis dental age 8-9 years
- Seldom ideal tooth of choice for relief of crowding
- But planned loss at correct age is better than later enforced loss
3 factors that inflluence the impact on the loss of 6s
- Age at loss
- Crowding
- Malocclusion – class II or III
age of loss of 6s
- Upper arch: Less important
- 7s will erupt in 6s position
- Lower arch: ideally at the time of bi-furcation development in 7s
- If L7s erupted (late) - Often poor space closure
- If too early – space - Distal drift of 5’s
crowding in upper arch
and 6 removal
potential for rapid space loss
crowding in lower arch
and 6 removal
spaced -> will have spaces
aligned -> will have spaces
crowded -> best results likely
2 fundamentals of 6s removal
compensation
balancing
compensation
6s extraction
- If U6 has to go NO compensation
- If L6 has to go then OFTEN compensation
- Get specialist opinion
balancing
6s extraction
- Not if spaced or well aligned
- Consider if premolar crowding
malocclsuion - class II or III
impact on 6s extraction
Class II upper molars are more important – can use space to relieve crowding or reduce overjet
Whereas in class III – lower molars are more important
unscheduled loss of central incisor
- In first instance maintain space = re implant
- Plan how to deal with space - Prosthesis?
Can get centre-line shifts and space loss which makes it harder for the orthodontist to create space and symmetry
3 variations in tooth size or form
- Too large – macrodontia
- Too small – microdontia
- Abnormal form
macrodontia
- tooth/teeth larger than average
- localised or generalised problems
- crowding
- asymmetry
- aesthetics
dealt with by restorative team and orthodontist
microdontia
- tooth/teeth smaller than average
- localised or generalised
- leads to spacing
- linked to hypodontia
6 types of abnormal tooth form
- Peg shaped laterals (diminutive)
- dens in dente
- geminated/fused teeth
- talon cusps
- dilaceration
- accessory cusps and ridge
abnormalities in tooth position
- ectopic
- transpositions
ectopic teeth tend to be
- can be any tooth but most commonly
- third molars (8s)
- upper canines (3s)
- first permanent molars (6s)
- upper centrals (1s)
ectopic canines occurance
- 1-3% of population
- 80% palatal
- associated with small or absent upper laterals
check for palpable buccal canine bulge from 9 years onwards
- Further investigation or refer if in doubt
4 parts of clinical assessment of ectopic canines
- Visualisation/palpation of any obvious bumps of 3
- Inclination of 2
- Mobility of c or 2 root resorption
- Colour of c or 2 loss of vitality due to root resorption
radiographic assessment of ectopic canines
- 2 radiographs needed to localise position
- usually OPT & anterior occlusal - vertical parallax
- 2 periapicals - horizontal parallax
- More accurate but likely already have OPT – also a larger view to assess any pathology
- usually OPT & anterior occlusal - vertical parallax
Parallax technique
- 3 Ps= presence, position, pathology
3Ps to look for in radiograph
Presence
Position (parallax technique)
Pathology
6 management strategies of ectopic canines
- Prevention
- Extraction c to encourage improvement in position of to encourage improvement in position of 3 (interceptive)
- Retain 3 and observe (accept its position)
- Surgical exposure and orthodontic alignment
- (Surgical) Extraction
- Autotransplantion
prevention of ectopic canines
- Appropriate monitoring from age 9 onwards.
- Clinical assessment
- Symmetry
issue of ectopic canine here
can see ectopic canine has taken away some of the lateral incisor roots
surgical exposure and orthodonic allignement of ectopic canine
- 63 present in the top picture*
- Bottom left can see 2 permanent canines area palatal to their deciduous teeth (53 and 63 present)*
- Surgically – not erupt expose them – if erupted leave them,*
- xtract deciduous canines, f*
- ixed appliance pull the permanent canine into their correct positions (bottom right)*
ectopic first molars (6s)
Less than 5%
- More commonly upper arch
Reversible before age 8
If left and not monitored Caries risk – plaque/food trap
ectopic first molars are sign of (2)
Sign of
- crowding
- mesial path of eruption
management of ectopic first molar (3)
- . Separator
- Between distal E and mesial 6
- Attempt distalize 6
- Orthodontically fix appliance
- Up righting it and allowing eruption
- extract
checks for ectopic upper central incisors
sequence
symmetry
why ectopic upper central incisors
supernumarary
dilacerated (trauma)
possible treatment for ectopic upper central incisors
- Surgical exposure
- removal of supernumerary emoval of supernumerary if present + Bond gold chain
- Make space
- above 9 yrs
- orthodonic traction
- bonded retainer
- above 9 yrs
*
issue in this radiograph
- 11 erupted, 21 not and 22 is erupting*
- Sequence wrong - investigate
- 61 is dark grey in colour*
- trauma?
- See permanent incisor above the 61*
- present and no obstructions or supernumeraries
- But the angle of 21 is not correct*
-
due to dilaceration
- root correct way,
- bend in root so crown is pointing in wrong direction
Need surgical and orthodontic treatment to correct
transpositions
Interchange in the position of two teeth
- Classification
- True (root and crown)
- Pseudo (just crown, root apices still correct location)
- Most commonly
- upper canines & first premolar
- lower canines & incisors
3 treatment options for transpositions
- accept
- extract – close space
- (correct) – only in mild pseudo transposition
3 local abnoralities of soft tissue
- digit sucking
- frenum
- tongue thrust
non-nutritional (digit) sucking
4 consequences on occlusion
- proclined UI
- retroclined LI
- anterior open bite
- unilateral posterior crossbite
- Thumb sucking causes negative pressure in the mouth*
- Prevents further transverse growth of maxilla – unilateral posterior crossbite
- Pushes upper incisors forwards – proclined*
- Lower incisors pushed into mouth – retroclined*
- Create gap - AOB*
labial frenum
may causes median diastema
Retract the lip and slightly pull on the frenum see blanching of interdental area between papilla and upper incisors
-
Leave until permanent canines erupted into positions – can cause spontaneous closure of diastema as the frenum regresses
- If persists and more than 3mm and concern to pt – can do frenectomy and orthodontically close space (need permanent bonded retainer for life)
tongue thrust
Pt put tongue between upper and lower teeth out the mouth
- Can cause
- AOB
- Splaying of teeth
- Spacing
reasons for tongue thrust
- Endogenous – medical issues (Downs); macroglossia
- Exogenous – habit (need to stop habit before tx to prevent relapse)
3 local pathology causes of malocclusion
- caries
- cysts
- tumours
