Effect of model resin and shaft taper angle on the trueness and fit of additively manufactured

removable dies in narrow ridge casts

Purpose. To evaluate how model resin and shaft taper affect the trueness and fit of additively

manufactured removable dies in narrow ridge casts.

Material and methods. A typodont model with a prepared mandibular molar was scanned to

design virtual dies with different shaft tapers (0-degree (straight), 5-degree, and 10-degree

tapered). Fifteen dies and one hollowed cast per taper were additively manufactured from two

resins (G-PRINT 3D Model, GP and DentaMODEL, DM). Dies and casts were digitized to

evaluate their trueness (root mean square (RMS)). The fit of the dies was evaluated with

crown portion’s RMS when seated in the cast and with distance deviations. Kruskal-Wallis

and Mann-Whitney U tests were used to analyze data (α =.05).

Results: GP dies had lower overall, root, and base RMS, while DM dies had lower crown

RMS (P≤.016). Straight dies had the highest overall, root, and base RMS within GP (P≤.030).

Ten-degree dies had the lowest overall and base RMS, lower crown RMS than straight, and

lower root RMS than 5-degree dies within DM (P≤.047). When the dies were seated, GP had

lower crown portion RMS within 5- and 10-degree dies, and 5-degree dies had the highest

RMS within DM (P≤.003). GP had lower distance deviations within 5- and 10-degree dies.

Five-degree dies had the highest deviations within DM (P≤.049).

Conclusions: GP dies mostly had higher trueness and better fit. Straight dies mostly had lower

trueness within GP. Ten-degree taper mostly led to higher trueness within DM. The shaft taper

affected DM dies’ fit.