Grammetry and Photogrammetry as impression tools in fullarch implant prostheses: is it a magical wand or a myth? A comprehensive critical review

Various technologies and techniques have been introduced to acquire implant position, orientation, and angulations, especially for completely edentulous full-arch implants. Intraoral and extraoral optical scanners, extraoral photogrammetry, grammetry and finally intraoral photogrammetry are different data acquisition methods for the fabrication of full-arch implant prostheses. Each of the previously mentioned methods depends on different scanning workflows, scan device designs, software manipulation of the acquired data, and post-scanning workflows, resulting in different degrees of accuracy.

Data collection was performed using the following keywords: Extraoral Photogrammetry, Intraoral Photogrammetry, Grammetry with particular attention to clinical trials and systematic reviews. Sources and Study selection: A comprehensive electronic search was conducted on PubMed, Scopus, and Web of science data bases. Articles published until 2025 were reviewed with a focus on clinical studies discussing each data acquisition workflow, software manipulation of each technology, and its relative effect on accuracy.

Conventional implant open tray impression will remain the gold standard; either intraoral optical scanning or photogrammetry have inherent inaccuracies in the workflow itself. Intra-oral photogrammetry may be a game changer after critical clinical research and applications, as it solves the problems of alignment and superimposition inaccuracies. Future research should prioritize clinical studies on the inherent errors of each workflow and how to avoid.

A full understanding of the underlying technology and workflow of each full-arch data acquisition technique will maximize the benefits of these recently proposed technologies. Therefore, this review aims to aid prosthodontists and clinicians in their selection process of digital acquisition methodology to be utilized in their full arch implant/prostheses cases. It also investigates the recent articles in the literature and highlights the gaps in the literature.