Crossbites

Question 1

Crossbites definition

Answer 1

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

Question 2

BUCCAL CROSSBITE:

Answer 2

• BUCCAL CUSPS OF
  MANDIBULAR TEETH OCCLUDE BUCCAL TO THE
  BUCCAL CUSPS OF THE MAXILLARY TEETH

Question 3

LINGUAL CROSSBITE

Answer 3

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

Question 4

Can have

Answer 4

Unilateral
Bilateral crossbites

Question 5

Bilateral lingual crossbite aka

Answer 5

Scissors bite

Question 6

Prevalence of crossbites
Population ?

Answer 6

8-22 percent of pop

Question 7

Percentage of orthodontic patients?

Answer 7

10 percent

Question 8

What percentage are bilateral?

Answer 8

2 percent

Question 9

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

Answer 9

3 times more common

Question 10

Classification?

Answer 10

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

Question 11

FEATURES OF A BILATERAL CROSSBITE?

Answer 11

ALWAYS SKELETAL IN ORIGIN
* OFTEN COMBINED WITH A SKELETAL III

Question 12

Unilateral crossbite without displacement is due to a

Answer 12

True asymmetry of the skeletal bases, usually pathological in origin

Question 13

For example

Answer 13

Unilateral cleft palate
Condylar hyperplasia

Question 14

Aetiology of crossbite

Answer 14

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

Question 15

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

Answer 15

Dentoalveolar/skeletal or both

Question 16

Why do we treat crossbites?

• SOME EVIDENCE THAT

Answer 16

DISPLACING CONTACTS MAY
PREDISPOSE A SUSCEPTIBLE INDIVIDUAL TO TMD.

Question 17

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

Answer 17

A CROSSBITE WITH
A DISPLACEMENT

Question 18

Therefore how to we treat crossbites

Answer 18

PREPARATION FOR BONE GRAFTING IN PATIENTS WITH CLP

Question 19

Which crossbites should we treat

Answer 19

NOT UNILATERAL OR BILATERAL CROSSBITES
WITHOUT DISPLACEMENT.

Question 20

Why?

Answer 20

THE MALOCCULSION IS OF MINOR IMPORTANCE.

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

Question 21

Timing of treatment of the deciduous dentition?

Answer 21

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

NB BUT NOT RECOMMENDED!

Question 22

TREATMENT OF CROSSBITES IN
THE MIXED DENTITION.

Answer 22

NO AND YES

Question 23

NO

Answer 23

LEIGHTON (1986) – SPONTANEOUS
CORRECTION FREQUENTLY OCCURS.

Question 24

YES

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Question 27

Appliances used to treat dentoalveolar crossbite?

Answer 27

UPPER REMOVABLE APPLIANCE
QUADHELIX
FIXED APPLIANCES

Question 28

Appliances used to treat skeletal crossbite?

Answer 28

RAPID MAXILLARY EXPANSION
SURGERY

Question 29

Photo expansion screw - listen to this bit

Question 30

Photo- coffin spring appliance- listen to this bit

Question 31

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

Answer 31

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

Question 32

Quadhelix
Force?
Activated by?
Works by?

Answer 32

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

Question 33

Adjustment of quadhelix? See photo

Answer 33

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

Question 34

Quadhelix vs upper removable appliance

Answer 34

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

Question 35

Crossbites and fixed appliances-
What appliances

Answer 35

Expanded arch wires
Through the bite elastics

Question 36

RME rapid maxillary expansion-use

Answer 36

• SHOULD NOT BE USED
  INDISCRIMINATELY.
• ONLY FOR SKELETAL CROSSBITES.

Question 37

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

Answer 37

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

Question 38

(Mechanics of RME)
The patient should be warned that

Answer 38

A median diastema may develop quickly during treatment

Question 39

(Mechanics of RME)
Force applied for RME?

Answer 39

2-5kg

Question 40

(Mechanics of RME)
Method of action?)

Answer 40

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

Question 41

(Mechanics of RME)
Expansion?

Answer 41

40 percent of expansion may be due to skeletal change

Question 42

Indications for RME?
Position
Discrepancy?

Answer 42

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

Question 43

Indications for RME
Age

Answer 43

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

Question 44

Indications for RME
Other?

Answer 44

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

Question 45

Expansion for correction of posterior crossbite… methods?

Answer 45

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