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ortho year 4 > Crossbites > Flashcards

Crossbites Flashcards

1
Q

Crossbites definition

A

CROSSBITE IS APPARENT WHEN THE BUCCAL
CUSPS OF THE LOWER TEETH OCCLUDE LATERAL TO
THE BUCCAL CUSPS OF THE UPPER TEETH.

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2
Q

BUCCAL CROSSBITE:

A
  • BUCCAL CUSPS OF
    MANDIBULAR TEETH OCCLUDE BUCCAL TO THE
    BUCCAL CUSPS OF THE MAXILLARY TEETH
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3
Q

LINGUAL CROSSBITE

A

(SCISSORS BITE):
BUCCAL
CUSPS OF MANDIBULAR TEETH OCCLUDE
LINGUAL TO THE LINGUAL CUSPS OF THE MAXILLARY TEETH

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4
Q

Can have

A

Unilateral
Bilateral crossbites

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5
Q

Bilateral lingual crossbite aka

A

Scissors bite

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6
Q

Prevalence of crossbites
Population ?

A

8-22 percent of pop

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7
Q

Percentage of orthodontic patients?

A

10 percent

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8
Q

What percentage are bilateral?

A

2 percent

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9
Q

In terms of pre-normal occlusions (class III)?

A

3 times more common

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10
Q

Classification?

A
  1. UNILATERAL BUCCAL CROSSBITE
    • WITH DISPLACEMENT
    • WITHOUT DISPLACEMENT
  2. BILATERAL BUCCAL CROSSBITE
  3. UNILATERAL LINGUAL CROSSBITE
  4. BILATERAL LINGUAL CROSSBITE (SCISSORS BITE)
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11
Q

FEATURES OF A BILATERAL CROSSBITE?

A

ALWAYS SKELETAL IN ORIGIN
* OFTEN COMBINED WITH A SKELETAL III

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12
Q

Unilateral crossbite without displacement is due to a

A

True asymmetry of the skeletal bases, usually pathological in origin

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13
Q

For example

A

Unilateral cleft palate
Condylar hyperplasia

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14
Q

Aetiology of crossbite

A
  1. HEREDITARY FACTORS …SKELETAL
  2. ENVIRONMENTAL FACTORS
    I. DIGIT SUCKING
    II. MOUTH BREATHING
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15
Q

Transverse anomalies like A-P anomalies can be (dentoalveolar/skeletal)

A

Dentoalveolar/skeletal or both

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16
Q

Why do we treat crossbites?

  • SOME EVIDENCE THAT
A

DISPLACING CONTACTS MAY
PREDISPOSE A SUSCEPTIBLE INDIVIDUAL TO TMD.

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17
Q
  • ALTHOUGH THIS EVIDENCE IS WEAK, …. IS THEREFORE A FUNCTIONAL
    INDICATION FOR ORTHODONTIC TREATMENT.
A

A CROSSBITE WITH
A DISPLACEMENT

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18
Q

Therefore how to we treat crossbites

A

PREPARATION FOR BONE GRAFTING IN PATIENTS WITH CLP

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19
Q

Which crossbites should we treat

A

NOT UNILATERAL OR BILATERAL CROSSBITES
WITHOUT DISPLACEMENT.

20
Q

Why?

A

THE MALOCCULSION IS OF MINOR IMPORTANCE.

THERE IS A CONSIDERABLE TENDENCY TOWARDS
RELAPSE – UP TO 40% WITH ALL FOR,SOF ACTIVE
EXPANSION

21
Q

Timing of treatment of the deciduous dentition?

A

SOME RECOMMEND GRINDING
1. TO ELIMINATE THE DISPLACING CONTACTS.
2. TO FACILITATE SPONTANEOUS CORRECTION

NB BUT NOT RECOMMENDED!

22
Q

TREATMENT OF CROSSBITES IN
THE MIXED DENTITION.

A

NO AND YES

23
Q

NO

A

LEIGHTON (1986) – SPONTANEOUS
CORRECTION FREQUENTLY OCCURS.

24
Q

YES

A

SCHRODER (1981) & PETREN (2003) – HIGH
FREQUENCY OF TRANSMITTANCE TO PERMANENT DENTITION

25
Q

RX.TREATMENT OF CROSSBITES IN
THE MIXED DENTITION –
CONSENSUS VIEW.

A
  • DO NOT BURN UP PATIENT CO-OP.
  • BEST WITH QUADHELIX.
  • CONSIDER LEAVING UNTIL LATER DEFINITIVE
26
Q

Photo- unilateral treatment in the mixed dentition listen to this bit

27
Q

Appliances used to treat dentoalveolar crossbite?

A

UPPER REMOVABLE APPLIANCE
QUADHELIX
FIXED APPLIANCES

28
Q

Appliances used to treat skeletal crossbite?

A

RAPID MAXILLARY EXPANSION
SURGERY

29
Q

Photo expansion screw - listen to this bit

30
Q

Photo- coffin spring appliance- listen to this bit

31
Q

Quadhelix- how does it work?
Spring?
Movement?
Wire?

A

Fixed expansion spring
Orthodontic and orthopaedic movement (<11 years movement)
1 MM hard SS

32
Q

Quadhelix
Force?
Activated by?
Works by?

A

Slow continuous force 0.5-1kg
Half a tooth width on either side
Combination of buccal tipping and skeletal expansion (6:1 ratio)

33
Q

Adjustment of quadhelix? See photo

A

At end of wire area 1.5cm movement laterally
At inner fold area 1cm laterally

34
Q

Quadhelix vs upper removable appliance

A
  • REMAINS FIRMLY IN PLACE.
  • DOES NOT RELY ON PATIENT CO-OP.
  • CAN DE-ROTATE 1ST MOLARS.
  • COST / BENEFIT (URA 40% MORE EXPENSIVE).
35
Q

Crossbites and fixed appliances-
What appliances

A

Expanded arch wires
Through the bite elastics

36
Q

RME rapid maxillary expansion-use

A
  • SHOULD NOT BE USED
    INDISCRIMINATELY.
  • ONLY FOR SKELETAL CROSSBITES.
37
Q

(Mechanics of RME)
Rapid maxillary expansion how does the patient work it

A

Patient turns the non spring loaded jackscrew once per day (0.2-0.5mm/day) for 1 to 3 weeks

38
Q

(Mechanics of RME)
The patient should be warned that

A

A median diastema may develop quickly during treatment

39
Q

(Mechanics of RME)
Force applied for RME?

40
Q

(Mechanics of RME)
Method of action?)

A

. L. Hyalinisation
* Bends alveolar process
* Opens mid-palatal suture

41
Q

(Mechanics of RME)
Expansion?

A

40 percent of expansion may be due to skeletal change

42
Q

Indications for RME?
Position
Discrepancy?

A
  • MX MOLARS & PMS BUCCALLY INCLINED.
  • DISCREPANCY >4MM B/N MX & MD MOLARS.
43
Q

Indications for RME
Age

A
  • UPPER LIMIT 10 -12 MM > SURGERY.
  • AGE 13 – 15 YEARS.
44
Q

Indications for RME
Other?

A
  • THE MID-PALATAL SUTURE USUALLY FUSES AROUND 15 YEARS,
    SURGICALLY ASSISTED RAPID PALATAL EXPANSION (SARPE) MAY BE
    CONSIDERED AFTER THIS TIME
45
Q

Expansion for correction of posterior crossbite… methods?

A
  1. RME FOLLOWED BY A TRANSPALATAL ARCH TO HOLD THE EXPANSION DURING FIXED APPLIANCE TREATMENT
  2. A QUADHELIX
  3. FIXED APPLIANCES WITH THROUGH THE BITE ELASTICS

ortho year 4 (11 decks)

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