arch expansion in orthodontics

ARCH EXPANSION IN

ORTHODONTICS DEPARTMENT OF ORTHODONTICS SUBHARTI DENTAL COLLEGE SWAMI VIVEKANAND SUBHARTI UNIVERSITY

Presented By: Dr Shalu Jain

INTRODUCTION

• Arch Expansion is a method of gaining space in Orthodontics.

• It is one of the oldest and most conservative method of gaining space.

• It can be used to correct intermaxillary and dental arch relationships primarily in the transverse direction. It also enables correction of crossbites early in treatment.

DrShalu Jain, Subharti Dental College, SVSU

Classification

1. Orthodontic or dental expansion- dentoalveolar in nature and produced by various removable expansion plates and conventional fixed appliances.

There is lateral tipping of crown and lingual tipping of roots.

2. Orthopedic or skeletal expansion- Changes

produced are skeletal in nature. Eg- Rapid maxillary expansion.


3. Passive Expansion- It is produced by shielding of buccal and labial muscles with a resultant expansion of the arches.

This type of expansion is produced by intrinsic forces such as those produced by the tongue. Eg- Fr-2 appliance and lip bumper.


ANATOMY

The maxilla is a paired bone that articulates with its opposite member and various other bones incl frontal, ethmoid, nasal, lacrimal, vomer, zygomatic and the palatine bones.

Most of the sutural attachments of the maxilla to the adjoining bones are at its posterior and superior aspects leaving the anterior and inferior aspects free, which makes it vulnerable for lateral displacement.


The inter-maxillary and the inter-palatine sutures are collectively called the mid-palatal suture.


Mid Palatine Suture plays a key role in R.M.E.

i. Infancy - Y-shape ii. Juvenile - T-shape iii. Adolescence - Jigsaw puzzle

As sutural patency is vital to R.M.E, it is important to know when does the suture closes by synostosis

An average 5% of suture in closed by age 25 yrs, range of ossification between 15-27 years Earliest closure occurs in girls aged 15 yrs and 18 years in boys.

Greater degree of obliteration occurs posteriorly than anteriorly.


Also known as rapid palatal expansion or

split palate.

It is a skeletal type of expansion that

involves the separation of the mid-palatal

sutures and movement of the maxillary

shelves away from each other.

Emerson C. Angell is considered the father

of rapid maxillary expansion.


INDICATIONS OF RAPID MAXILLARY EXPANSION

• Posterior crossbites

• Class III malocclusion- Dental or skeletal cause.

• Cleft Palate patients

• Face mask therapy

• Medical indications- Nasal stenosis, poor nasal airway, septal deformities, allergic rhinitis.

• Selected arch lenghth problems- In selected patients in whom extraction could lead to flattening of profile.


TYPES OF APPLIANCES USED

Fixed appliances- (a) Tooth borne

(b)Tooth & Tissue borne


FIXED APPLIANCES

• Appliances that are fixed onto the teeth are more reliable and found to produce consistent skeletal effects.

• TOOTH AND TISSUE BORNE APPLIANCES-

1. Derichsweiler type

2. Hass type

TOOTH BORNE APPLIANCES-

1. Isaacson type

2. Hyrax type


1. Derichsweiler type- The first premolars and first molars are banded. Wire tags are soldered onto the palatal aspect of the band. These wire tags get inserted into a split acrylic plate incorporating a screw at its centre.


2. Hass type- The 1st premolar and molar of either side are banded. A thick stainless steel wire is soldered on the buccal and lingual aspect connecting PM and M bands. The lingual wire is kept longer to extend past the bands. The split palatal acrylic has a midline screw.


3. Isaacson type- This a tooth borne

appliance without any acrylic palatal

covering. This design makes use of a

spring loaded screw called a minne

expander.


4. Hyrax type- This type of appliance

makes use of a special type of screw

called HYRAX ( Hygienic rapid expander).

The screws have heavy gauge wire

extensions that are adapted to follow the

palatal contour and are soldered to bands

on premolars and molars.


EFFECT OF R.M.E. ON THE MAXILLARY COMPLEX

• Rapid maxillary expansion occurs when the force

applied to the teeth and the maxillary alveolar

processes exceeds the limits needed for orthodontic

tooth movement.

• The applied pressure acts as an orthopaedic force

that opens the midpalatal suture.


• The appliance compresses the periodontal

ligament, bends the alveolar processes, tips

the anchor teeth, and gradually opens the

midpalatal suture.


OCCLUSAL VIEW

• Palatine processes of the maxillae separated in a nonparallel— that is, in a wedge-shaped


FRONTAL VIEW

• The maxillary suture was found to separate

superoinferiorly in a nonparallel manner.

• It is pyramidal in shape with the base of the

pyramid located at the oral side of the bone.


MAXILLARY ANTERIOR TEETH • From the patient's point of view, one of the

most spectacular changes accompanying RME

is the opening of a diastema between the

maxillary central incisors.


EFFECT OF R.M.E. ON MANDIBULAR COMPLEX

• The mandible rotates downward and backwards due to the

downward movement of the maxillary posterior teeth in a

buccal direction.

• The palatal cusps of the maxillary posterior teeth, which

should ideally occlude in the occlusal grove of the

mandibular posterior teeth, tend to occlude with the

lingual slopes of the buccal cusps of these teeth, there by

giving the effect of opening the bite


EFFECT OF R.M.E. ON THE NASAL CAVITY

• The RME tends to increase the intranasal

space as the outer walls of the nasal cavity

move apart and the palatal shelves flatten out,

making the nasal floor broader.


ACTIVATION OF THE RME APPLIANCE

• Forces generated are close to 10 to 20 pounds.

• An expansion of 0.2 to 0.5 mm should be

achieved per day.

• Screw activated at between 0.5 to 1mm per day

and about 1 cm of expansion can be expected in

2 to 3 weeks


• Timms - activation of 90°,morning and evening - patients

up to age of 15 years

In patients above this age- suggests an activation of 45°

four times a day.

• Zimring and lsaacson recommended, two turns per day

initial 4 to 5 days followed by one turn per day in growing

individuals.

For adults : two turns each for the first two days followed

by one turn per day for the next 5 to 7 days and then only

one turn every alternate day till the desired expansion is

achieved. DrShalu Jain, Subharti Dental College, SVSU

1. Single tooth crossbites

2. Uncooperative patients

3. RME is not carried out after ossification of the midpalatal suture unless accompanied by adjunctive surgical procedures.

4. Vertical growers with steep mandibular plane.

Dr Shalu Jain, Subharti Dental College, SVSU

5. Skeletal asymmetry of maxilla and mandible and adult cases with severe antero-posterior skeletal discrepancies.

6. Periodontally weak dentition.


• Oral hygiene

• Length of fixation

• Dislodgement and breakage

• Tissue damage

• Infection

• Failure of suture to open

Dr Shalu Jain, Subharti Dental College, SVSU

SURGICALLY ASSISTED RAPID PALATAL EXPANSION (SARPE)

Patients who exhibit unusual resistance to separation of palatine bones may require surgical intervention. This usually occurs in female patients over 16 years of age and male patients over 18 years of age.

It may also be required in patients exhibiting increased circum maxillary rigidity as a result of aging.


The main resistance to maxillary skeletal expansion comes from the buttressing effect of zygomatic and sphenoid bones at their point of attachment to the maxilla.

SARPE involves surgical separation of these attachments thereby allowing expansion to be achieved using a conventional RME appliance.

Expansion is carried out at a rate of 0.5mm per day. It has a high relapse tendency because of inelasticity of palatal mucoperiosteum and a degree of overcorrection is valuable.


arch expansion in orthodontics

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