Clinical influence of digital vs analog impressions in all-on-4 implant prostheses: a randomized controlled trial

To compare the clinical outcomes of conventional and digital implant impressions in all-on-4 mandibular implant prostheses.

Fifty-six participants were randomly stratified into two control groups (Axial Conventional Impression Group [ACIG] and Tilted Conventional Impression Group [TCIG]), and two test groups (Axial Digital Impression Group [ADIG] and Tilted Digital Impression Group [TDIG]). Conventional pick-up and digital impressions were made for each group, respectively. Participants in ACIG and ADIG received four axial implants, and those in TCIG and TDIG received two anterior axial and two distal tilted implants. All participants received all-on-4 mandibular prostheses and maxillary complete dentures. Implant survival, prosthetic complications, and marginal bone loss were recorded at 6, 12, and 24 months. Data were statistically described in terms of mean ± standard deviation.

After 24 months, the implant survival rate was 100%. A significant difference in bone loss was shown between ACIG and ADIG at 6, 12, and 24 months, with P = 0.647, 0.821, and 0.505, respectively. An insignificant difference in bone loss was shown between TCIG and TDIG at 6 ,12, and 24 months, with P = 0.671, 0.935, and 0.687, respectively. No significant difference was shown in prosthodontic complications between all groups throughout the follow-up period.

The digital impressions showed clinically better implant survival, stable peri-implant marginal bone level, and reasonable prosthodontic complications. The present study represents a steppingstone and proof of concept that supports the routine clinical use of digital impressions, especially in a post-COVID-19 world.