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
RX.TREATMENT OF CROSSBITES IN THE MIXED DENTITION – CONSENSUS VIEW.
* DO NOT BURN UP PATIENT CO-OP. * BEST WITH QUADHELIX. * CONSIDER LEAVING UNTIL LATER DEFINITIVE
26
Photo- unilateral treatment in the mixed dentition listen to this bit
27
Appliances used to treat dentoalveolar crossbite?
UPPER REMOVABLE APPLIANCE QUADHELIX FIXED APPLIANCES
28
Appliances used to treat skeletal crossbite?
RAPID MAXILLARY EXPANSION SURGERY
29
Photo expansion screw - listen to this bit
30
Photo- coffin spring appliance- listen to this bit
31
Quadhelix- how does it work? Spring? Movement? Wire?
Fixed expansion spring Orthodontic and orthopaedic movement (<11 years movement) 1 MM hard SS
32
Quadhelix Force? Activated by? Works by?
Slow continuous force 0.5-1kg Half a tooth width on either side Combination of buccal tipping and skeletal expansion (6:1 ratio)
33
Adjustment of quadhelix? See photo
At end of wire area 1.5cm movement laterally At inner fold area 1cm laterally
34
Quadhelix vs upper removable appliance
* REMAINS FIRMLY IN PLACE. * DOES NOT RELY ON PATIENT CO-OP. * CAN DE-ROTATE 1ST MOLARS. * COST / BENEFIT (URA 40% MORE EXPENSIVE).
35
Crossbites and fixed appliances- What appliances
Expanded arch wires Through the bite elastics
36
RME rapid maxillary expansion-use
* SHOULD NOT BE USED INDISCRIMINATELY. * ONLY FOR SKELETAL CROSSBITES.
37
(Mechanics of RME) Rapid maxillary expansion how does the patient work it
Patient turns the non spring loaded jackscrew once per day (0.2-0.5mm/day) for 1 to 3 weeks
38
(Mechanics of RME) The patient should be warned that
A median diastema may develop quickly during treatment
39
(Mechanics of RME) Force applied for RME?
2-5kg
40
(Mechanics of RME) Method of action?)
. L. Hyalinisation * Bends alveolar process * Opens mid-palatal suture
41
(Mechanics of RME) Expansion?
40 percent of expansion may be due to skeletal change
42
Indications for RME? Position Discrepancy?
* MX MOLARS & PMS BUCCALLY INCLINED. * DISCREPANCY >4MM B/N MX & MD MOLARS.
43
Indications for RME Age
* UPPER LIMIT 10 -12 MM > SURGERY. * AGE 13 – 15 YEARS.
44
Indications for RME Other?
* THE MID-PALATAL SUTURE USUALLY FUSES AROUND 15 YEARS, SURGICALLY ASSISTED RAPID PALATAL EXPANSION (SARPE) MAY BE CONSIDERED AFTER THIS TIME
45
Expansion for correction of posterior crossbite... methods?
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