Chapman Prize 2020: Prescription of full or part-time Twin Block wear: A randomised controlled trial and qualitative evaluation Pratik Sharma Padhraig Fleming. BOC 2021.September 22nd 2021. Episode 128

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Hosted by
Farooq Ahmed


Join me as summarise this year’s Chapman Prize 2020 by Pratik and Padhraig

Lecture based on 2 studies published in the AJODO

  • Effectiveness of part time Vs full time wear protocols of twin block appliance on dental and skeletal changes RCT AJODO 2019
  • Understanding factors influencing compliance with removable functional appliances. A qualitative study AJODO 2019



Full time 22hrs, Vs 12 hours



  • Design, cribs 6s, 4s, ball clasps lowers, edge to edge bite
  • Modification: Theramon sensor imbedded into the acrylic block 10mm x 7mm
    • Detects changes in temperature – to assess compliance
  • Patients seen 6-8 weeks



  • Part time Vs full time:
    • Overjet change: 7mm Vs 6.5mm
    • Pog increase : 3 Vs 3mm No difference
    • ANB 1.5 Vs 1.25
  • Compliance
    • Part time
      • Reporting 11 hrs
      • Actual wear 8.8 hrs – statistically different to reported compliance
    • Full time
      • Reporting 20 hrs
      • Actual wear 12.4 hrs – statistically different to reported compliance


  • No difference in skeletal and dental changes
  • Part time wear 8-13 hours achieves dental and skeletal changes
  • Patients over report wear
  • Future research: re-activation of block can have more positive effects


Qualitative research Padhraig Fleming



  • 1 to 1 interview, 22 patients
  • Full time and part time
  • Topic guide: experience and compliance



  • Themes
    • Self motivation
      • Positive reinforcement from clinician or parents
    • Social influence
      • Teasing initially
    • Quality of live impairment and adaptability
    • Perceived treatment progress
    • Pragmatic
      • Forgetfulness
      • Speech and effects on schooling
    • Part time
      • Possible confusion of time



  • Initial 4 weeks – maximum social impairment, speech, forgetfulness
  • After 4 weeks
    • Positive parents
    • Positive clinician
    • Facial changes


First month

  • Communication including parents
  • Not wearing whilst eating
  • Taper introduction


Timing / phasing school

  • Part time wear during school
  • Time fit in holidays


Overall treatment

  • Full time after 4 weeks
    • To maximise changes


Manage failure

  • Night time wear only


Design consideration

  • Minimise visible parts
  • Simple
    • Avoid labial bow, limit vertical opening





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