The Evolution of Mini-implant Assisted Midfacial Expansion, the Latest Developments and Advanced Applications Won Moon. AAO June 2021. Episode 86

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Farooq Ahmed

The Evolution of Mini-implant Assisted Midfacial Expansion, the Latest Developments and Advanced Applications Won Moon

Age range for palatal suture opening with TAD assisted expansion unknown

o   Cases up to 50 years of age

§  Question: Do the sutures in the skull fuse? We are unsure at this stage


MSE: Maxillary Skeletal Expander

How does it work

·      Miniscrew retained palatal expander

·      4 miniscrews

·      Posterior maxilla 1st molar region

·      Due to posterior position in thin bone, bicortical engagement required

·      Position of MSE determines the pattern of expansion = posterior expansion


Transverse changes

·      Parallel expansion of the midpalatal suture

·      MSE creates disjunction of pterygopalatine suture 84% Colak 2020

·      Center of rotation of MSE = zygomaticomasillary complex

o   Maxilla moves forwards and laterally

o   Bone tipping 1-2 degrees of palatal shelfs with MSE, 8-9 degrees with hyrax


Vertical changes

·      Interzygomatic expansion 4.4mm

·      Nasal cavity 5.3mm


Failure of MSE

·      Primary reason is not achieving bicortical engagement



·      Other appliances

o   Tooth borne expansion: Average expansion 6mm, 2.4mm relapse long term Schiffman 2001 S/R.

o   SARPE: Chamberland 2011: Intermolar distance relapsed, skeletal component of relapse 41%

·      MSE: No significant literature, Won’s cases after 2 years appear stable with clinical and radiographic assessment


Comparing MSE to MARPE

·      Difference between MARPE Vs MSE

o   Force vector distal in MSE, Vs anterior position for MARPE

o   MSE achieves parallel expansion, MARPE triangular

o   Study assessing 50 patients, showed parallel expansion Colak 2020



o   SARPE lower level of ration around le fort 1 osteotomy site Cantarella 2018

o   MSE greater expansion at zygomatic level than SARPE due to centre of rotation


Does MSE change the functional matrix?

o   Compared novel angular measurements – accounting for rotational changes

§  Percentage of skeletal expansion 96% Vs 4% dento-alveolar changes

o   Linear measurement – not ideal as does not account for rotational effect

§  Skeletal 60% Vs dental tipping 24%


Latest development MSE

·      Digital planning from STL file and CBCT Dicom, ensuring bicortical engagement

o   Digital planning site of TADs Contarella 2020


Expansion protocol

o   Large biological variation

§  Activate until tight – one or two more activations (5-6 per day)


Hard and thick bone

MSE protocol for SMARPE

·      Palatal cortipuncture

·      Piezotome ANS – PNS

·      MSE and score buttress bone

o   5 x cortipuncture, facilitates MSE expansion Suzuki 2018

o   SARPE – combine MSE for greater rotational benefit, Surgical and micro-implant assisted rapid palatal expander SMARPE



·      Volume increase in nasal cavity with MSE Cantarella 2017

·      Airflow improvement significant improvement approximately 100 PNIF (1/3 improvement)

·      Reduce nasal resistance

·      CBCT data, issues are pharangeal airway changes in size during function and use

o   Live MRI can be used

·      MSE and Sleep Apnea

o   Significant improvement in OSA in adults, RCT submitted for publication


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