Intro Flashcards
Benefits and risk of ortho treatment
Improved function and aesthetics VC reduced dental health and failure to achieve aims
Health benefits of ortho
Reduces caries susceptibility - straighter terth- less caries? Not proven
Reduced gingivitis and perio - straighter teeth easier to clean, depends on OH habits: but correcting crossbites and trumatic overbite will help with recession and periodontal trauma
Reduced trauma risk/ correcting increased overjet- if overjet more than 6 mm- 3x increased risk of trauma; trauma risk reduces with age
Improved masticatory function- increased overjet/ anterior open bite can lead to eating difficulties
Improved speech- not proven as malocclusion has little impact on speech (speech is complex neuromuscular process and position of teeth has a small influence on that)
Reduces risk of tooth impaction/ pathology - unerupted teeth can lead to cystic change and resorption; supernumerary teeth can cause failed eruption (e.g. impacted incisor)
Improved aesthetics/ psychological effect- dentofacial anomalies /severe malocclusion have negative impact on self- esteem and quality of life
Risks of ortho treatment
Dental caries/ decalcification - poor oral hygiene and cariogenic diet
Root resorption/ root shortening
Ginigivitis/ loss of attachment increases in pt with unstable perio ( if during the ortho, perio comes back- loss of attachment will be accelerated)
Soft tissue trauma- ulcers caused by brackets and wires
Assessing risks and benefits
Comprehensive pt assessment and planning needed
- caries risk status, perio assessment, previous trauma-root resorption
Index of orthodontic treatment need (IOTN)- developed to help determine the likely impact of malocclusion on dental health and psychological well being
Treatment strategies
- Ortho only
- interceptive (mixed dentition)
-growth modification (functional appliance)- usually for class II occlusion
- comprehensive - adolescent/early adulthood
-limited objective- alignment only/accepting other features - Ortho + surgical
- impacted teeth ( removal or exposure)
- orthognatic surgery - Ortho + restorative
-e.g. laterals are missing, space made by ortho as canines have shifted mesially so if they are repositioned distally, that will allow space to restore missing laterals
Indications for ortho
Motivated pt
Stable dental health
Caries free minimum 12 months
Healthy periodontium
low plaque scores/ good OH
Benefits of ortho treatment outweighs the risk
Contraindications for ortho
Poor dental health (active caries, perio issues)
OH issues
Poor co-operation/tolerance issue
Low treatment needs (IOTN)
Types of ortho appliances
Removable
Fixed
Functional
Removable appliances
An orthodontic appliance that can be removed by the pt
Design:
1. Active component -moving the teeth , e.g. palatal finger spring
2. Retentive component - holding the teeth in place, e.g. Adam clasp
3. Anchorage (Newton 3rd law of motion)
4. Baseplate/ bite planes
Advantages: can be removed for cleaning (after meals), cheap (compared to fixed appliances), less chair side time, has palatal coverage allowing good anchorage
Disadvantages: it is removable so risking reduced compliance, limited tooth movements possible ( only tipping, cannot rotate teeth), lower appliance is poorly tolerated
Clinical tips/considerations:
Initial fit is passive, demo fit and removal to the pt, stress the full time wear except cleaning, warn about the speech, no XLA until compliance is confirmed, review every 4weeks, assessing compliance - wear signs can be seen on mucosa, speech has returned to normal, gentle activation of active components
Indications:
1. Alignment of mesially-inclined canines
2. Crossbite reduction
3. Overjet reduction- not anymore used
4. Overbite reduction
5. Eliminate occlusal interferences
6. Adjunct to fixed appliance
7. Space maintenance
8. Retention
Rarely seen nowadays to be used alone, usually in combination with a fixed appliance treatment plan
Contraindications:
1. Multiple tooth movements
2. Complex tooth movements
- intrusion/extrusion
- bodily movement
- de-rotation
What is anchorage
For every force applied there is an equal and opposite reactionary force
Anchorage relates to control of these reactionary forces
3 planes: anterior/posterior, vertical, transverse
URA mode of action
Simple tipping movement -tooth will tip around its centre of rotation (junction of apical third and coronal 2/3rds). Light forces (25-3/ grams)
Movement enabled through the bony remodelling
Area of tension is where deposition of bone happens
Area of compression is where resorption of bone happens
Functional appliances
Removable or fixed ortho appliance which uses forces generated by the stretching of muscles, fascia and/or periodontium to alter skeletal and dental relationships.
Benefits:
In growing pt
Correcting the malocclusion of skeletal origin
Commonly used in class II pt with mandibular retrognathia
Hoping to enhance mandibular growth and restrain maxillary growth
Ideal functional appliance pt:
Growing pt
Class 2, div 1 malocclusion
Mandibular retrognathia
Average or reduced vertical proportions
Increased OJ/OB
Mainly well aligned arches
Mode of action:
1. Dentoalveolar (dental effect):
Tipping movements (class 2, div 1- upper centrals retroclination, lower centrals proclination), eruption guidance (achieved with bite planes/capping - anterior and posterior that will produce different eruption, inhibit eruption of upper posteriors, encourage mesial eruption of lower posteriors (class 2 correction)
- Skeletal (orthopaedic or growth effects):
Restriction of maxillary growth
Increased rate of mandibular growth (elongation is brought about by deposition at the condyle and the posterior border of the ramus)
Remodelling changes in the TMJ - Modification of soft tissue activity
- lip competency, changing the linguo-facial muscle balance, teeth erupt into a position of balance
All functional appliances use some or all of:
Eruption guidance- bite planes
Mandibular repositioning- working bites
Altering soft tissue balance- shields and modifying lip activity
Classification:
Tooth borne( twin block) -mostly for dental tipping, good retention, well tolerated
Soft tissue borne-less retention, difficult to achieve 24 h wear
Fixed functionals
- Twin block: tooth borne via clasps, full time wear if possible, separate upper and lower appliance, bite blocks posture the mandible forward
Fixed appliance
Ortho appliance fixed/attached to the teeth
Heavy forces can be applied (100-150gms) so allows bodily movements
So all of the buccal portion of the root surface is area of tension causing bone deposition and all the palatal/lingual PDL area is under compression causing bone resorption
Indications:
Multiple tooth movement
Space closure with bodily movement
Intrusion/extrusion of teeth
Rotation correction
Overbite control with incisor intrusion
Mild to moderate skeletal discrepancies
Severe skeletal discrepancies +surgery
Advantages:
Complex cases treatment
High standard of finishing
Wear co-operation is not essential but OH and diet are
Less bulkier than removable
Do not affect speech
Disadvantages:
Diet restriction and meticulous OH needed
Can cause iatrogenic effects (decalcification)
Can cause ortho root resorption (shortening)
Require special skills and training
Require close monitoring
Components of fixed appliance
Archwire
Bracket- control tooth position in combination with archwire; 0.022” sloth width size, slot is specific for each tooth (by prescription), base of the bracket is mashed to retain composite better, curved to fit each tooth , can be precoated (adhesive) or non pre coated
Elastic ligature
Archwires
Different shapes and sizes
Round are more flexible for lighter movement, for alignment phase
Square
Rectangular - more aggressive - more movement
Alloy types:
NiTi- highly flexible, has shape memory- for initial alignment phasr
Stainless steel- high stiffness and rigidity, decreased flexibility; working archwires, allow levelling, space closure, finishing
B-titanium (TMA) - half way between NiTi and SS- some flexibility but more rigid than NiTi. Useful in finishing stages of treatment
Transpalatal arch (TPA)
Across upper arch between molars
Soldered or removable attached to molar bands
Allows increased posterior anchorage
Maintains molar width
