Class III Jaw orthopedic early treatment for young patients (Age 10-14) without surgery (En)
Dr.Schwan Somsiri

Rapid Maxillary Expander (RME) & Face Mask

What is RME?

RME stands for Rapid maxillary expander. It is a special device for enlarging your dental arches and floor of the nose making your breathing through the nose easier or normal. It composes of a jack screw in the middle of the appliance, which will be fixed with a special type of cement in the middle of palatal vault.

This is not an orthodontic treatment, since it will expand the top jaw, it is called Jaw or Dentofacial Orthopedic Treatment.


  • To enlarge the nasal cavity making your nasal breathing normal.

  • To treat asthmatic patient or chronic allergic rhinitis or the upper respiratory tract obstruction syndrome (due to hyperactivity of the tonsilar tissue) under the age of 16

  • To eliminate the posterior cross bite (upper teeth bite inside) making your bite normal, which can prevent the incidence of TMJ disorders.

  • To normalize your speech.

  • As an introduction treatment, in order to break the circum maxillary sutures and make forward traction of the maxilla by a FACE MASK possible in early treatment of Class III malocclusion, which can reduce the rate of surgery to advance the maxilla. The optimum age for this orthopedic treatment is around the age of 10. At the age of 14 forward traction of the maxilla by a FACE MASK is impossible.

  • Over the age of 16 Rapid maxillary expander can be used in combination with modified Le Fort I maxillary osteotomy to expand the palatal vault in adult patient up to the age of 30.

How to use RME to enlarge your maxillary dental arches (Top Jaw) and nasal cavity?

Follow this direction for turning the screw of RME

  • For safety reason, use only the key provided by your orthodontist only

  • Insert the key gently into the key hole and slowly push the key – in the arrow direction – into the throat until the end of the stroke

  • If you do it correctly, a new key hole will be seen.

  • Take the key out

  • Do not turn the key in a reverse direction

  • Turn the key 2 times a day, one in the morning and one in the evening.

  • Total amount of turns is 28 turns. 4 Turns equal 1 mm. Total turning time is 14 days. See your orthodontist once a week to check for correctness.

In 3 days you will be able to see that the upper front teeth are split apart, do not be panic! This means that the palate is successfully split apart.

The next hole of the screw will be seen for the next turn.

In adult patient, in combination with a modified Le Fort I maxillary osteotomy, RME can be turned 3 times a day.

Within 14 days you can expand the palate up to 7 mm ( after 28 turns) You will see the upper 2 front teeth spread apart approximately 6-7 mm, which shows that the expansion is successfully done. Your doctor may want you to turn the screw more than 28 turns in some case.

The space in between the upper 2 front teeth will be gradually closed by itself with time. If this is not the case your doctor will close it for you.

The RME will be left in place for approximately 9 months for remineralization of the palatal bone.

Properties of the RME

RME must be rigid enough to withstand the tension (resistance) from the maxillary sutures, the palatal bone and soft tissue during expansion and retention. We recommended RME screw from Dentaurum or Forestadent or Leone.

RME which is not rigid enough will tend to tip the molar teeth outwards (buccally), due to torque effects, not to split the palate and provide bodily expansion. So the palatal cusps of the upper molar teeth will tend to hang down causing premature (traumatic) contacts with the opposing teeth, which will lead to TMD.

According to Indication No.5 the use of FACE MASK must be initiated on the 2nd day of expansion. Because the circum maxillary sutures repair itself rapidly. You will have time to pull forward the maxilla only 6 weeks. If the traction was not seriously and consistently performed, the maxilla will not be advanced at the required amount, making the success of the treatment approach zero.

Remember: You have to advance (pull forwards) the maxilla (top jaw) to see the overjet (the upper front teeth cover the lower front teeth in horizontal plane) for 5 mm. This is the amount of overcorrection, and in a year or two, you will see that the front teeth will fit together nicely. If the amount of overcorrection cannot be reached, the treatment result can be jeopardized, which will result in the return of anterior cross-bite (underbite).

Pulling or advancing the maxilla after the 6th week will yield very little result. Its intention is only to retain the result for another 6 weeks. The healing in the maxilla take place very rapidly.

Side effect of RME

  • Pain and discomfort

  • Chewing difficulty, but this is well adapted in young child.

  • Asymmetrical expansion, due to different bony resistance of the right and left half of the maxilla

  • Part of the appliance immerge into the palatal soft tissue

  • Temporarily TMD signs and symptoms (Clicking)

Disadvantage of RME

After active phase of RME (activation) the appliance should be left in place for 9 months so that new bone can be laid down.

Every cases of RME must be finished with fixed multiband and bracket Edgewise therapy (MBB)

If you have any question please fell free to contact our office.

ศูนย์ทันตกรรม และข้อต่อขากรรไกร Dental and Jaw Joint (TMD) Center

Dr. Schwan Somsiri
31/70 Soi Jaeng Wattana – Pakkred 34
Jaeng Wattana Rd., Pakkred, Nonthaburi 11120. THAILAND

Tel. 02-574-0555, 02-574-6556, 02-984-4568
Fax 02-573-4050
Mobile 081-495-4486, 087-700-9919

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