Accuracy of Digital Impressions at Varying Implant Depths: An In Vitro Study

Abstract

Purpose Implants placed at variable depths may vary the amount of visible scannable surface of a scan body. Intraoral scanner technology uses advanced optical principles to record the surface of the scan body to accurately capture the implant position. The purpose of this study is to investigate the effect implant placement depth has on the accuracy of digital implant impressions using an intraoral scanner. Materials and methods A partially edentulous gypsum master model was fabricated to allow the positioning of a single implant analog at different depths. Four groups were created based on the planned implant depths of 7, 6, 3, and 0 mm and corresponding visibility of the scan body at 2, 3, 6, and 9 mm. The model was digitized with a laboratory scanner for the reference scan and with an intraoral scanner to generate 15 test scans per group, with a total of 60 scans. The test scans were superimposed onto the reference scan using the best fit algorithm to analyze and measure the positional (dXYZ) and angular deviation (d⍬) of the scan body using three‐dimensional metrology software. Statistical analysis was performed using a one‐way ANOVA and pairwise comparison was done with a Tukey‐Kramer HSD test (α = 0.05). Results The one‐way ANOVA of the groups for the dXYZ and dθ parameters was statistically significant (F3,56 = 11.45, p < 0.001, F3,56 = 24.04, p < 0.001). Group D (9 mm) showed the least positional deviation at 38.41 μm (95% CI 30.26; 46.56) and the least angular deviation of 0.17° (95% CI 0.12; 0.21). Group A (2 mm) showed the greatest positional deviation of 77.17 μm (95% CI 65.23; 89.11) and greatest angular deviation of 0.84° (95% CI 0.65; 1.03). The positional and angular deviation increased with increased implant depth. Conclusions The accuracy of digital impressions is influenced by the implant depth and the amount of visibility of the scan body. The trueness and precision are highest when the implant is placed at 0 mm depth with complete visibility of the scan body and decreases with subgingival implant placement.

A guide for maximizing the accuracy of intraoral digital scans: Part 2—Patient factors

“…[36][37][38][39][40] Implants Interimplant distance Implant position, angulation, and depth Inconsistencies are present in the literature regarding the influence of interimplant distance, implant position in the dental arch, and implant angulation and depth on intraoral scanning accuracy. [36][37][38][39][40][41][42][43][44][45][46][47] • In general, scanning discrepancies increases as interimplant distance increases. 46,47 • The implant positioned in the dental arch at the end of the intraoral digital scan obtains significantly higher distortion than the contralateral implant.…”

“…[36][37][38][39][40][41][42][43][44][45][46][47] • In general, scanning discrepancies increases as interimplant distance increases. 46,47 • The implant positioned in the dental arch at the end of the intraoral digital scan obtains significantly higher distortion than the contralateral implant. 45 • Contradictory results have been reported regarding the influence of implant angulation on intraoral scanning accuracy.…”

“…[41][42][43][44][45][46][47][48][49][50] Some studies have reported that implant angulation decreased the accuracy of the digital scans compared to the conventional impressions, or that implant angulation decreased the scanning accuracy of IOSs. 41,44,46,47,50 However, other studies have shown that implant angulation had no effect on intraoral scanning accuracy. 42 Implant depth is related to clinical implant scan body height.…”

“…[41][42][43][44][45][46][47][48][49][50][51][52] However, inconsistencies are present in the dental literature regarding the influence of these variables on intraoral scanning accuracy. [41][42][43][44][45][46][47][48][49][50][51][52] Additional studies are needed to further assess the influence of implant related factors on scanning accuracy of IOSs. Photogrammetry systems provide a digital alternative to acquire the 3D position of the implants.…”

“…The distance between two adjacent implants, as well as implant position in the dental arch, implant angulation, and depth of the existing implants have been identified as variables that can decrease intraoral scanning accuracy. [41][42][43][44][45][46][47][48][49][50][51][52] However, inconsistencies are present in the dental literature regarding the influence of these variables on intraoral scanning accuracy. [41][42][43][44][45][46][47][48][49][50][51][52] Additional studies are needed to further assess the influence of implant related factors on scanning accuracy of IOSs.…”