Factors Influencing the Fit and Retention of Computer-aided Design/Computer-aided Manufacturing-based Three-dimensional Printed Band and Loop Space Maintainers

INTERPROXIMAL CONTACT

Interproximal contact is very critical for the retention of the band and loop. Recording the interproximal area is crucial for the design. The interproximal contact between the second primary molar and first permanent molar is very difficult to record. This area is usually broad, and the contact is usually I type in terms of the OXIS classification,² if there is a completely erupted permanent molar, the amount of space is also limited. Recording this interproximal area with an intraoral digital scanner is very challenging. This area again depends on factors such as the eruption status of the adjacent permanent molar. If the adjacent permanent molar is fully erupted and if there is an I type of broad contact area, then most often it requires proximal slicing to record the area for the intraoral scanner. Furthermore, caution should be taken to prevent accidental nicking during interproximal slicing, as bleeding can interfere with the quality of the scan and result in loss of detail. If the adjacent permanent molar is unerupted or partially erupted, the band area in the distal proximal area should be designed in such a way that it does not interfere with the eruption of the adjacent permanent molar. In clinical scenarios where the second primary molar has pronounced anatomical characteristics, such as a pronounced buccal bulge, achieving a proper gapless fit with CAD/CAM design, especially in the occlusal third, is seldom possible. In a few clinical scenarios, due to the lack of interproximal space between the second primary molar and the adjacent first permanent molar, the design of the band has to be done in such a way that the band design distoproximally incorporates the marginal ridge distally to some extent for retention (Fig. 1), in such scenarios, there is a rise in the bite due to the same reason. Minimal occlusal adjustments can be done to improve the fit. Alternatively, the modification of the design can be accomplished by removing the distal part of the band, but this has a lower retention rate compared to the full design (Figs 2 and 3). Literature reports few case reports of CAD/CAM based 3D printed space maintainers.^3,4 The disadvantages, along with methods to overcome them, also need to be discussed to improve the clinical adaptability of digital technology in pediatric dentistry.