THE INFLUENCE OF THE POST-PRINTING PROTOCOL ON THE PRINTED ALIGNERS THICKNESS AND COLOUR-A PILOT STUDY

Abstract

Aim To assess the thickness and colour differences between the aligners printed according to the material manufacturer's instructions and aligners with the modified post-printing protocol. Materials and Method Aligners were printed from the STL files using NextDent Ortho Flex resin (NextDent B.V., Soesterberg, The Netherlands) with prototype printer IZZI Direct (3Dtech, Zagreb, Croatia) in three designed thicknesses of 0.5, 0.6 or 0.7 mm. The first group of aligners was produced according to the manufacturer's instructions, while the other group had modified post-printing protocol with post-polymerization done immediately after printing, omitting the strain of the residual resin. Two samples of each thickness for the upper and lower jaw were printed, 24 aligners in total. Three independent measurers measured the thickness on 40 different points using an electronic micrometer (ELECTRONIC UNIVERSAL MICROMETER 909.785, Schut Geometrical Metrology, Groningen, The Netherlands) with an accuracy of 0.001 mm and compare colour and transparency with thermoformed clear aligner (Duran+, SCHEU-DENTAL GmbH, Iserlohn, Germany). Results From the first group of aligners, 37.5% of measured points were within the ±10% range of the predetermined thickness, with 36.25% of the points being more than 10% thicker than designed. Aligners with a designed thickness of 0.5, 0.6 and 0.7 mm had 47.5%, 32.5% and 32.5% of points in the stated range, respectively. Although specified as clear and transparent upon printing, aligners showed a yellowish hue. The group with modified post-printing protocol had 41.25% of measured points within the ±10% range of the predetermined thickness with 35.84% of the points being more than 10% thicker than designed. Aligners with a designed thickness of 0.5, 0.6 and 0.7 mm had 33.75%, 43.75% and 46.25% points in the stated range, respectively. This group of aligners showed transparency and clarity similar to thermoformed clear aligners. Conclusions Our data suggest that modified post-printing protocol can influence material properties. In this case, omitting the recommended strain of the residual resin resulted in aligners with thickness values generally closer to the original design and also with better aesthetics more similar to thermoformed clear aligners.

Full text

Ivna Vuković Kekez 1, Ružica Bandić 1, Katarina Vodanović 1, Ivana Medvedec Mikić 2,3, Danijela
Kalibović Govorko 1,3*


 !"
#$%&'%!&(%)*++++,+++,-./,.++.
THE INFLUENCE OF THE POST-PRINTING PROTOCOL ON THE PRINTED ALIGNERS
THICKNESS AND COLOUR-A PILOT STUDY
Aim
0& 1'2!!
  3 !24,!%
Materials and Method
5!2064 !7897:%;%'!
07<2*==*9=!')<!
&+%-+%>+%?%
04! !2 !  3 2
! 4,!2,@A!
B! %02& 2$22
C!%0  &C+1
!96)07*)7*;56*)0.+.%?/- D
!D!07<2 +%++ 
2!9 E)",7056D'"*D<%
Results
84! !?%-F 22G+F!
&2>%-F'!+F&!%5!
2!&+%-+%>+%?C?%-F%-F%-F
!%5 !4 !!2
2 %
0! 24,!C%-F 2G+F!
&2-%/CF'!+F&!%
5!2!&+%-+%>+%?%?-FC%?-FC>%-F
!%0! !2
!%
Conclusions
  !!4,!H %*
B!  !2& 
!!!2'I
!%

02,4'  !8 
J!))+C,++