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
Stability
· 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
MSE Vs SARPE
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
Airway
· 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
