Category: orthodontics

SERIAL EXTRACTION

Anisha ValliLeave a comment

Defined as correctly timed, planned removal of certain deciduous and permanent teeth in mixed dentition cases with dentoalveolar disproportion

  1. Introduced by KJELLGREN 
  2. Father of SE = nance 1940
  3. RATIONALE
    1. Arch length deficiency as compared to the tooth material using Model analysis method
    2. Physiological tooth material = eg wilkinson extraction of 1st permanent molar
  4. FACTORS THAT PLAY ROLE IN CORRECTION OF CROWDING IN ANTERIOR SEGMENT
    1. Leeway space of nace 
      1. Max = 1.8 mm
      2. Mand = 3.4 mm
    2. Tongue pressure 
    3. Interdental spacing 
    4. Incisal liability = amount of space available and required by permanent tooth
      1. Max = 7 mm
      2. Mand = 5mm 
  5. INDICATIONS 2m
    1. Tooth material and arch length discrepancy of 10mm
    2. Class I malocclusion 
    3. Absence of Spacing 
    4. Midline shift 
    5. Premature loss of primary canine
  6. CONTRAINDICATIONS 2m
    1. Class II and Class III malocclusion 
    2. Anodontia
    3. Oligodontia
    4. Deep bite 
  7. ADVANTAGES =  Prevents fixed appliances and malocclusions in the pt
  8. DISADV = 
    1. Long follow up = pt compliance
    2. Operator = highly trained 
    3. Delay of permanent tooth 
  9. DWELLS PROCEDURE
    1. Extraction of three teeth 
      1. Primary canine = at age of 8-9 years
      2. Primary 1st molar = at age of 9-10 years
      3. 1st premolar 
    2. Always bilateral extraction in the same arch 
    3. If done unilateral = midline shift happens 
    4. In the 1 st Step, the deciduous canines are extracted to create a space for alignment of the incisors. This step is carried out at 8-9 years of age. 
    5. After 1 years, the deciduous 1st molars are extracted so that the eruption of 1st premolars is accelerated. 
    6. This is followed by the extraction of the erupting 1 st premolar to permit the permanent canines to erupt in their place. 
  1. TWEED METHOD = D4C
  1. NANCE METHOD = D4C 
  • BOTH methods involve the extraction of the deciduous 1 st molars around 8 years of age. This is followed by the extraction of the 1 st premolar & the deciduous canines. 
  • MOYERS METHOD = based on intercanine width = BCD4
    1. Maxillary arch 
      1. Boys = 10 years
      2. Girls = 9 years
    2. Mandibular arch 
      1. Boys = 18 years
      2. Girls = 12 years

ACTIVATOR

Anisha ValliLeave a comment

DEFINITION = Functional appliances are defined as ‘loose fitting or passive appliances which harness the natural forces of the orofacial musculature that are transmitted to the teeth and alveolar bone through the medium of appliance’.

ACTIVATOR 4m**

  1. Given by anderson and haul
  2. Also called as norwegian appliance or loose fitting appliance
  3. It doesn’t have any clasp to hold onto dentition normally 
  4. Only one wire component = labial bow

Mechanism of action 2m

  1. Pt has to forcibly hold the appliance in its place aka maxilla as its loose appliance with no clasps
  2. This causes the pt to bring his mandible forward and keep mouth closed so the activator doesn’t fall down. 
  3. When pt swallows = muscles get stretched, continous remodeling at TMJ and mandible stays in forward direction
  4. Mandible is staying forward due to a REFLEX – myotatic reflex = due to continuous stretch of muscles, kinetic energy is generated and transferred to maxillary and mandibular dentition and skeletal base. Leading to: 
    1. Distal force on maxilla
    2. Mesial force in mandible 
    3. Hence, condylar adaptation occurs
  5.  ‘viscoelastic property’ = passive tension caused by stretching of muscles, soft tissue, tendinous tissue, etc. are responsible for the action


Indications 2m

  1. Class II division 1 malocclusion
  2. Class II division 2 malocclusion
  3. Class III malocclusion
  4. Class I open bite malocclusion
  5. Class I deep bite malocclusion
  6. As a preliminary treatment before major fixed appliance therapy to improve skeletal jaw relations
  7. For post­ treatment retention
  8. Children with lack of vertical development in lower facial height.

Contraindications

  1. Crowding 
  2. Adult pt 
  3. Too much proclination of lower anteriors 
  4. Increased lower anterior facial height

Advantage

  • pt can remove it
  • oral hygiene is maintained
  • no food restrictions
  • chair side time is less

Disadvantage = pt compliance

TYPES of activator 

  1. H activator 
    1. Horizontally growing pt
  2. V activator 
    1. Vertically growing pt 

FABRICATION STEPS

  1. Take impression
  2. Bite registration = gives us an idea how much mandible needs to be displaced. U shaped wax is placed on the oral cavity and asked to bring it forward and the bite is also opened posteriorly. 
  3. Articulation
  4. Wire elements  
  5. Acrylization of appliance
  6. Trimming = to bring about certain movements of the dentition

MODIFICATIONS 

BOW ACTIVATOR 

  • WUNDERER MODIFICATION = Given in class 3 
  • CYBERNATOR = similar to bionator = activator with reduced palatal acrylic 
  • PROPULSOR
  • Cutout or palate free activator
  • Karwetzky modification 
  • Herren modification 
  • Elastic open activator
  • Kinetor by Stockfish 

TYPES OF ORTHODONTIC FORCES

sakshibhude1 Comment

Continuous force- active force that decreases little in magnitude betwwen appointments.

  • Light weight appliances
  • Highly flexible appliance components used which are activated at low force level.
  • No interference with biological function and no harm to soft tissues.
  • Direct resorption of bone

Intermittent force- active force that decays to zero before next appointment.

  • High stiffness appliances
  • Twice the force activation for corresponding soft tissue deformation
  • Undermining resorption and corresponding tooth movement.

Interrupted force- inactive for intervals of time between appointments

  • Cyclic, long term magnitude time pattern
  • Heavy forces delivered
  • No force decay

Reference- orthodontics bhalajhi

TYPES OF TOOTH MOVEMENTS

sakshibhudeLeave a comment

Can be categorized into 3 categories-

  • Pure translation- intrusion and extrusion, bodily movement
  • Pure rotational- torquing and tipping
  • Generalized rotational

1. Tipping- single force applied results into movement of crown in direction of force and movement of root in opposite direction.

A) Controlled tipping- When tooth tips about centre of rotation at apex. Lingual movement of crown with minimal movement of root in opposite direction.

B) Uncontrolled Tipping- when movement of tooth occurs about centre of rotation close to centre of resistance. Crown moves in lingual direction and root in opposite direction.

2.Torquing – reverse tipping characterized by lingual movement of root.

3. Bodily movement- All points on tooth will move equal distance in the direction of applied force. Line of action of force is through centre of resistance.

3. Intrusion- bodily displacement of tooth in apical direction along longitudinal axis of tooth.

4. Extrusion- bodily displacement of tooth in coronal direction along longitudinal axis of tooth.

5. Rotational- labial or lingual movement of tooth around long axis

6. Uprighting- when crowns are tipped in mesiodistal direction roots tipped in opposite direction. Tipping the roots back to get parallel orientation is called uprighting.

Reference- ortho bhalajhi