MARPE – SARPE: Sense and NON-sense Björn Ludwig 

Join me for a summary of Björn Ludwig’s lecture exploring Miniscrew Assisted Rapid Palatal Expansion (MARPE) and Surgically Assisted Rapid Palatal Expansion (SARPE). Björn described how MARPE works, aspects of design and his clinical process.

Effects of MARPE

• Parallel opening of suture 2mm greater at 6 region than RME (S/R Krusi 2019)
• Facial changes
  • Widens Zygoma 
  • Nasal base expands
  • Changes to the orbit – no significant but beware Brutally invasive!
• No periodontal side effects with MARPE (limited evidence) S/R Vidalon 2021 

• RME Vs bone borne, hybrid = bone borne no dental side effects: Canan 2017

Age

MARPE  Vs RME

• Age up to 11, no difference in outcomes Bazargani 2021 

Retention after MARPE

At 7 months: suture has not fully remodelled

• Retention is needed for 1 year to allow full remodelling
• Type of retainer 
  • TPA does not maintain bony changes Prado 2014
  • TPA with TADs = prevent bony relapse 

Expansion rate of MARPE

• Fast Vs slow bone borne
  • Fast (2-3 x activation per day) Vs slow (2 activations per week)
    • Slow expansion MARPE: Sutural opening still occurs Pulver 2016 (Rabbit study) 
    • No diastema

Activation process: Force controlled polycyclic activation

• Activation occurs if the force is 500g, key indicates activation Winsauer 2021

Airflow

• Increase in airflow with MARPE
• White paper from AJODO on OSA – limited evidence
  • Our job is to get rid of crossbites NOT to resolve OSA
• MARPE effective at resolving crossbite S/R: Kapetanović 2019  
  • MSE reduce OSA: Brunetto and Moon 2022 
    • Björn considered a good side effect, not the main cause

Class 3

• RME most effective in class 3 cases
• Alt-Ramec  Eric Liou 2005
• 3 x day = maxilla moves downwards and forwards due to position of buttress

• • Facemask
    • Facemask in the night, and class 3 elastics in the day
      • A point advance 3mm: MARPE + facemask study: Maino 2018

• Realistic ½ unit correction – borderline correction

SARPE Vs MARPE 

• SARPE mainly changes maxilla, maintains aspects of midface
• MARPE changes to midface

Design features

Arms to 1st molars Vs no arms 

Arms prevent distal rotational movement when activate MARPE

• Additional screws no difference 4 or 6 Winsauer 2013 

Position of screws

Posterior screws reduce rotation 

• BUT very thin bone, penetrate nasal base but of little consequence as the floor of the sinus lifts 1-2mm (6-7mm then signs of perforation)
• Posterior TADs do allow for bicortical engagement (Moon)
  • Placement at an angle distally around 6 region (towards teeth)
    • Björn states limited use for anchorage posterior palate, main use prevent distal rotation

Design type

MSE Vs power screw

• Björn considers the argument not as important as the practicality, main features are:
  • The TAD used 
  • Abutment connecting TAD to expander
  • Expansion screw type

Insertion guide

• Biocompatible material Formlabs Surgical Guide Resin
• Individual guide Vs stock
  • Stock: Slight deviation between clinical insertion Vs planned insertion
• Tip : MARPE plan to have lab open screw by 5 turns so it can be adapted chairside by opening / closing
• Contra-angle Vs straight insertion: 
  • Contra-angle preferred as less opening required when factor screw and insertion plate

Weak point in design

• Failure can occur between abutment (housing for screw) and expander
  • Forces high (5-10N 1kg scary high) – the weakest aspect
  • Björn recommends laser welding or 1 piece metal printing  (Andre Walter 2017)

Planning

• Digital planning 
  1. After planned insertion of tads
  2. Assemble abutments, screw – power screw, design arms
     • Digital planning to allow adaptation of hybrid, MSE – Pirate style!
• Tip: 2 arms to 6s to prevent tipping

Delivery

• 1 appointment to place screws and expander 
• Insertion TADs 60rpm 
• Secure with floss – 2 have been swallowed (with Björn)
• Secure expander with fixation screw 
• Start activation – Bond up lower arch same time to decompensate

Take home messages

• Hi tech is good but low tech is key
• No body said it was easy, and orthodontics is not easy

For more information see  Benedict Wilmes guest blog on Kevin O’Brien’s Orthodontic Blog