Load distribution in fixed space maintainers: a strain-gauge analysis.

Purpose: The purpose of this study was to compare the biomechanics of space maintainers supported by primary and permanent teeth.

Methods: Photoelastic models of permanent and primary teeth with a single missing tooth space were cast, and band-and-loop, direct-bonded, and fiber-reinforced space maintainers were fabricated. Linear strain-gauges were bonded next to the teeth and in the middle of the missing tooth space. Strain gauge signals were quantified during 50 N and 100 N static axial load applications on the molar, maintainer, and anterior support at 10 KHz using a data acquisition device and associated computer software.

Results: Regardless of the tooth being restored, strains around the molar teeth and the maintainer region were comparable between the groups under molar and maintainer loading (P>.05). Under 100 N loading on the anterior support, the highest strains were observed in the direct-bonded group (P<.01). Direct-bonded design led to higher strains than the band-and-loop design under 100 N maintainer loading, whereas the strain output of other designs were comparable.

Conclusion: Load distribution of band-and-loop, direct-bonded, and fiber-reinforced space maintainers seem comparable, although direct-bonded maintainers could lead to higher strain concentrations in the buccal side due to bending moments.