Intraoral scan bodies in implant dentistry: A systematic review

Systematic Review


Abstract

Statement of problem

Intraoral scan body (ISB) design is highly variable and its role in the digital workflow and accuracy of digital impressions is not well understood.

Purpose

The purpose of this systematic review was to determine the relevant reports pertaining to ISBs with regard to design and accuracy and to describe their evolution and role in the digital dentistry workflow. Special attention was placed on their key features in relation to intraoral scanning technology and the digitization process.

Materials and methods

A MEDLINE/PubMed search was performed to identify relevant reports pertaining to ISB usage in dentistry. This search included but was not limited to scan body features and design, scan body accuracy, and scan body techniques and the role of ISBs in computer-aided design and computer-aided manufacturing (CAD-CAM) processes. Commercially available scan bodies were examined, and a patient situation was shown highlighting the use of ISBs in the digital workflow.

Results

Deficiencies in the reports were found regarding various scan body topics, including ISB features/design, accuracy, and the role of ISBs in CAD-CAM processes.

Conclusions

ISBs are complex implant-positioning-transfer devices that play an essential role in the digital workflow and fabrication of accurately fitting implant-supported restorations. With scanner technology rapidly evolving and becoming more widespread, future studies are needed and should be directed toward all parts of the digital workflow when using ISBs. By understanding the basic components of ISBs and how they relate to digital scanning and CAD-CAM technology, more emphasis may be placed on their importance and usage in the digital workflow to ensure accurate transfer of implant position to the virtual and analog definitive cast. Efforts should be made by clinicians to identify an optimal ISB design in relation to the specific intraoral scanning technology being used.
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Digital evaluation of absolute marginal discrepancy: A comparison of ceramic crowns fabricated with conventional and digital techniques

Research and Education


Abstract

Statement of problem

Marginal discrepancy is key to evaluating the accuracy of fixed dental prostheses. An improved method of evaluating marginal discrepancy is needed.

Purpose

The purpose of this in vitro study was to evaluate the absolute marginal discrepancy of ceramic crowns fabricated using conventional and digital methods with a digital method for the quantitative evaluation of absolute marginal discrepancy. The novel method was based on 3-dimensional scanning, iterative closest point registration techniques, and reverse engineering theory.

Material and methods

Six standard tooth preparations for the right maxillary central incisor, right maxillary second premolar, right maxillary second molar, left mandibular lateral incisor, left mandibular first premolar, and left mandibular first molar were selected. Ten conventional ceramic crowns and 10 CEREC crowns were fabricated for each tooth preparation. A dental cast scanner was used to obtain 3-dimensional data of the preparations and ceramic crowns, and the data were compared with the “virtual seating” iterative closest point technique. Reverse engineering software used edge sharpening and other functional modules to extract the margins of the preparations and crowns. Finally, quantitative evaluation of the absolute marginal discrepancy of the ceramic crowns was obtained from the 2-dimensional cross-sectional straight-line distance between points on the margin of the ceramic crowns and the standard preparations based on the circumferential function module along the long axis.

Results

The absolute marginal discrepancy of the ceramic crowns fabricated using conventional methods was 115 ±15.2 μm, and 110 ±14.3 μm for those fabricated using the digital technique was. ANOVA showed no statistical difference between the 2 methods or among ceramic crowns for different teeth (P>.05).

Conclusions

The digital quantitative evaluation method for the absolute marginal discrepancy of ceramic crowns was established. The evaluations determined that the absolute marginal discrepancies were within a clinically acceptable range. This method is acceptable for the digital evaluation of the accuracy of complete crowns.
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CS 3600 Intraoral Scanner Outperforms Other Scanners, Traditional Impression, in Finish Line Accuracy


ATLANTA—Since its launch in 2016, the accuracy of Carestream Dental’s CS 3600 intraoral scanner has been consistently confirmed by international third-party scientific research. Now, the scanner has once again been recognized for its outstanding performance in finish line accuracy.
Finish Line Distinctness and Accuracy in 7 Intraoral Scanners versus Conventional Impression: An In-vitro Descriptive Comparison,”* published in BMC Oral Health, aims to highlight differences, if any, in finish line distinctness and finish line accuracy among seven intraoral scanners and one traditional impression.
The study defines finish line distinctness as “the degree of visual clarity and identifiability in the reproduction of the finish line compared to a reference scan,” and finish line accuracy (FLA) as “the ability of a measurement to match the actual value of a reference scan in the immediate proximity to the finish line.” In this case, a model with a screw retained crown and a preparation for a cemented crown was scanned with a highly accurate industrial scanner to act as the reference scan.
One traditional impression was taken of the base model while each of the seven scanners captured 10 digital impressions each on the model; the tenth scan from each scanner was used to evaluate finish line distinctness and accuracy.
Based on “color deviation evaluation and distribution of deviations in histogram,” the CS 3600 shared the top rank among the scanners for highest finish line accuracy, with a deviation below ±25 μm. The study also stated the CS 3600 showed a clear and distinct color rendering, which the researchers purposed may “assist in identifying the finish line compared to the monochromatic .STL files.”
Also, while the CS 3600 consistently ranked higher in both finish line accuracy and distinctness than the traditional impression, that was not true for all scanners tested.
“In modern dentistry, we assume that digital will naturally give us better results than analog,” Ed Shellard, D.M.D., chief dental officer, Carestream Dental said. “However, this study shows that not all scanners are created equal when it comes to providing better results than traditional impressions.”
Ultimately, the study states that there are “sizeable variations between intraoral scanners with both higher and lower finish line distinctness and finish line accuracy than impressions” and encourages clinicians to “critically evaluate [a] digital impression, being aware of technical limitations and system specific variations among intraoral scanners.”
To learn more about the CS 3600 intraoral scanner, or any other of Carestream Dental’s innovative solutions, please contact 800.944.6365 or visit carestreamdental.com.
*Nedelcu R, Nystrom I, Olsson P, Thor A. Feb. 26, 2018. Finish Line Distinctness and Accuracy in 7 Intraoral Scanners versus Conventional Impression: An In-vitro Descriptive Comparison. BMC Oral Health.18(27): DOI 10.1186/s12903-018-0489-3
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About Carestream Dental
Carestream Dental provides industry-leading dental digital product lines and services, including imaging equipment, CAD/CAM systems, software and practice management solutions, for dental and oral health professionals. With more than 100 years of industry experience, Carestream Dental technology captures two billion images annually and aids in more precise diagnoses, improved workflows and superior patient care. For more information or to contact a Carestream Dental representative, please call 800.944.6365 or visit carestreamdental.com.
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Superimposition of 3D digital models: A case report

Original Article


Summary

Introduction

Superimposition of digital models may be performed to assess tooth movement in three dimensions. Detailed analysis of changes in tooth position after treatment may be achieved by this method.

Aim

This article describes the method of superimposing digital models with a clinical case. It emphasizes the difficult procedure of superimposing 3D models in the lower arch. A methodology for superimposing mandibular models acquired with a structured light 3D scanner is discussed.

Conclusion

Superimposition of digital models is useful to analyse tooth movement in the three planes of space, presenting advantages over the method of cephalogram superimposition. It seems feasible to superimpose digital models in the lower arch in patients without growth by using a coordinate system based on the palatal rugae and occlusion. The described method aims to advance the difficult procedure of superimposing digital models in the mandibular arch, but further research is nonetheless required in this field.
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