Error propagation from intraoral scanning to additive manufacturing of complete-arch dentate models: An in vitro study

Abstract

ObjectivesTo evaluate deviation propagation from data acquisition with an intraoral scanner to additive manufacturing of complete-arch dentate models. MethodsA reference (Ref) mandibular dentate model having 5 precision spheres was scanned with a coordinate measurement machine equipped with a laser scanning head (ALTERA; Nikon) producing a Ni reference data set (n = 1). Digital impressions were taken of the Ref model with intraoral scanner (IOS) (Trios4; 3Shape) with Insane (T4_Imo) and Classic (T4_Cmo) scanning modes (each n = 10). T4_Imo scans were used as a second reference data set and to produce test models with two additive manufacturing (AM) devices (each n = 10): MAX UV385 (Asiga) and NextDent 5100 (3DSystems). As for the control group, dual viscosity vinyl polysiloxane impressions were taken of the Ref model and poured with Type IV dental stone (n = 10). All AM and stone models were scanned with a laboratory scanner (E4; 3Shape). Trueness and precision of linear (intermolar and intercanine width, arch length) and surface deviations were measured between reference (Ni, T4_Imo), test (T4_Cmo, AM), and control (stone) groups using best-fit alignments (Geomagic Control X; 3D Systems). The normality of data and differences between the groups were analyzed using Shapiro-Wilk, Levene's, Mann-Whitney U, Welch's t-test statistical analysis (p<0.05). ResultsThe accuracy of the IOS impression was not significantly affected by the scanning mode (p>0.05). Stone models showed significantly better trueness than IOS impressions (p<0.05). AM models had higher trueness than IOS Imo digital impressions (p<0.05). The precision of AM models was comparable (linear, p>0.05) or lower (surface, p<0.05) than of IOS Imo digital impressions. Trueness was insignificantly different among the stone and AM models (p>0.05). Higher trueness was achieved by Max UV385 than with Nextdent 5100 (p<0.05). The majority of linear and all surface deviations of IOS impressions and AM models were below 200 μm. ConclusionsWithin the limitations of this in vitro study, digital IOS impressions and AM models using the aforementioned equipment have acceptable accuracy for orthodontic and prosthodontic applications when complete-arch dentate records are used. Clinical SignificanceIOS and AM devices can have a significant influence on error propagation when applying digital workflow with complete-arch dentate models