Intaglio surface trueness of dentures bases fabricated with 3D printing vs. conventional workflow: a clinical study.

The latest generation of intraoral scanners can record the prosthetic field with relative ease, high accuracy and comfort for the patient, and have enabled fully digital protocols for designing and manufacturing complete dentures. The present study aims to examine the intaglio surface trueness of 3D printed maxillary dentures produced by fully digital workflow in comparison with dentures produced by analogue clinical and laboratory prosthetic workflow. The edentulous maxillary arch of 15 patients was scanned with an intraoral scanner as well as the intaglio of the delivered conventional denture. The scan of the edentulous arch was imported into a dental design software to produce the denture base which was then 3D printed. The intaglio surface of the finished 3D printed denture bases was digitized and used to assess the trueness of the printed denture bases compared to the intaglio surface of the conventional dentures as well as performing a trueness comparison in relation to the scanned edentulous arches. The dataset (n = 30) was subjected to Kruskal-Wallis test analysis, the significance level being established at α = 0.05. The results of the study showed that the printed group displayed better trueness values with a median of 176.9 µm while the analogue group showed a median of 342 µm. Employing a fully digital workflow to produce 3D-printed denture bases yields a consistent and precise manufacturing method when accounting for the intaglio surface of the denture.

Marginal fit of milled versus different 3D-printed materials for provisional fixed dental prostheses: an in vitro comparative study.

Introduction: Provisional dental prostheses are used as interim restorations to help patients perform oral functions between the time of tooth preparation and the placement of the final restoration. A provisional dental prosthesis should protect the abutment from pulpal and gingival aggressions, adapt correctly to keep healthy gingival tissues, be durable, and have a low price. The purpose of this in vitro study was to compare the marginal adaptation of different types of provisional fixed dental prostheses (PFDP), fabricated using 3D printing technology versus the milling (computer-aided manufacturing [CAM]) technique. Method: Two resin teeth (second premolar and second molar) on a typodont were prepared for three-unit provisional fixed dental prostheses. Thirty models were 3D-printed after a digital model was created using an intraoral scanner. Then, 30 provisional fixed dental prostheses (PFDPs) were made from a variety of materials using a digital design of a 3-unit PFDP and STL files delivered to a milling machine and a 3D printer, respectively. Ten PFDP were milled (CAM), and two sets of ten each, were fabricated with 3D printing technology (stereolithography), using two different materials. All restorations were analyzed under a microscope, and marginal gap was then measured using the software Image J. Results: The milled group presented the best marginal gap values (ranging from 86 to 108 µm) and a median value of 93 µm, followed by GC group with (110-251 µm) with a median value of 205 µm and the PR group with median value of 316.5 µm. Conclusion: According to the findings of this in vitro study, the milling (CAM) technique and SLA technology provides acceptable marginal fit values to fabricate provisional fixed partial dentures.

Scanning Distance Influence on the Intraoral Scanning Accuracy-An In Vitro Study.

Intraoral scanners (IOS) have reached a point where their impact in the dental office cannot be denied. The distance between the tip of the IOS and the preparation may have implications on the accuracy of the digital model. The objective of this study was to evaluate the differences in accuracy between digital impressions in the scenario of different scanning distances. Twenty consecutive scans were performed at five predetermined distances: 5 mm, 10 mm, 15 mm, 20 mm and 23 mm by a single operator. The scanning distance of 10 mm displayed the best accuracy with an overall trueness value of 23.05 µm and precision value of 4.2 µm. The drawn conclusion was that increased scanning distances can decrease the accuracy of a digital impression.

Can Dental Office Lighting Intensity Conditions Influence the Accuracy of Intraoral Scanning?

The aim of this study was to evaluate the influence of different settings of ambient light intensity inside the dental office on the accuracy (trueness and precision) of an intraoral scanner (IOS). A full crown preparation was conducted on a resin molar which was scanned using a high resolution extraoral scanner to obtain a reference model. Six light settings were chosen based on the most clinically relevant light conditions inside the workspace, and the preparation was scanned using an intraoral scanner (PlanScan, Planmeca). The obtained data was analyzed using a professional 3D quality control software (Geomagic Control X). There was no statistically relevant difference between the groups when regarding trueness, although a slight influence of the light intensity could be observed on the trueness values. Regarding precision, the best results were obtained in the 3800 lux group, with the other groups presenting close values, excepting the extreme values (400 lux and 11 000 lux) groups that proved to be the most deficient.

Trueness and Precision of Two Intraoral Scanners: A Comparative In Vitro Study.

The aim of this study was to evaluate the accuracy of two intraoral scanners used in the dental office. A molar fixed in a typodont was prepared for a ceramic onlay. The preparation was scanned using a high-resolution scanner (reference scanner) and saved as stereolithography (STL) format. The prepared resin molar was scanned again using the intraoral scanners, and all the scans were saved as well in STL format. All STL files were compared using metrology software (Geomagic Control X). Overlapping the meshes allowed the assessment of the scans in terms of trueness and precision. Based on the results of this study, the differences of trueness and precision between the intraoral scanners were minimal.