Enhancing Intraoral Scanning Accuracy for Edentulous Mandibular Arches Using Resin Markers: An In Vitro Study

To evaluate intraoral scan (IOS) accuracy for implants placed in edentulous mandibles when intraoral resin markers are used. Two commonly used intraoral scanners were assessed under simulated oral mucosa conditions to determine the effect of resin markers on IOS accuracy.

A mandibular study model with four implants and simulated unattached mucosa was fabricated. The model was scanned using two intraoral scanners (TRIOS 4, 3Shape; Primescan, Dentsply Sirona), both with and without flowable composite resin markers applied between scan bodies. A total of 30 scans were captured per scanner (15 without markers, 15 with markers), resulting in four IOS groups: TR (TRIOS 4), PS (Primescan), TRmark (TRIOS 4 with markers), and PSmark (Primescan with markers). Indirect digitization was performed via conventional impressions, stone model fabrication, and laboratory scanning (IND group). A reference scan (REF) was obtained using a high-accuracy laboratory scanner (E4, 3Shape). All scan files were analyzed in Geomagic Control software. Root-mean-square (RMS) values were calculated for trueness and precision. Kruskal-Wallis test was used to evaluate group differences, followed by pairwise comparisons (α = .05).

Trueness analysis revealed significant differences between groups (P < .001). IND exhibited the highest trueness, followed by TRmark, PSmark, and PS, while TR showed the lowest trueness. Precision analysis indicated significant influence of the scanning method (P < .001). PSmark, TRmark, and IND showed the highest precision, and TR had the lowest precision. The addition of resin markers significantly improved both trueness and precision for TRIOS 4.

Indirect digitization remains the most accurate method for full-arch implant scanning. Scanner type affects IOS accuracy, with Primescan demonstrating higher accuracy than TRIOS 4 without resin markers. Resin markers significantly improved IOS accuracy, particularly for TRIOS 4, where both trueness and precision increased. The clinical implications are that while conventional impressions with splinted impression copings remain the gold standard, IOS accuracy for edentulous mandibular arches can be significantly improved with the use of simple resin markers, offering a practical and cost-effective enhancement to digital workflows. The use of resin markers is a viable technique to enhance scan reliability without requiring additional specialized equipment.