Intraoral Scanners in Dentistry: A Review of the Current Literature

Francesco Mangano; Andrea Gandolfi; Giuseppe Luongo; Silvia Logozzo

BMC Oral Health. 2017;17(149)

Background

Intraoral scanners (IOS) are devices for capturing direct optical impressions in dentistry.^[1–3] Similar to other three-dimensional (3D) scanners, they project a light source (laser, or more recently, structured light) onto the object to be scanned, in this case the dental arches, including prepared teeth and implant scanbodies (i.e. cylinders screwed on the implants, used for transferring the 3D implant position).^[2,3] The images of the dentogingival tissues (as well as the implant scanbodies) captured by imaging sensors are processed by the scanning software, which generates point clouds.^[3,4] These point clouds are then triangulated by the same software, creating a 3D surface model (mesh).^[3,4] The 3D surface models of the dentogingival tissues are the result of the optical impression and are the 'virtual' alternative to traditional plaster models.^[4,5]

Although IOS are becoming widespread in clinical dental practice, only a few reviews on the use of these devices are available in the literature.^[5–8]

The purpose of the present narrative review was therefore to:

identify the advantages and/or disadvantages of using optical impressions compared to conventional impressions;
investigate if optical impressions are as accurate as conventional impressions;
evaluate the differences between the IOS currently available commercially;
determine the current clinical applications and limitations in the use of IOS;

taking into consideration all studies currently available in the scientific literature.

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Table 1. Advantages and disadvantages of optical impressions according to the current literature
Advantages	Disadvantages
Less patient discomfort [2,4,6,7,9–18]	Difficulty detecting deep marginal lines of prepared teeth [2–5,26,29–33]
Time-efficient [6,13,15,16,18–24]	Learning curve [29–34]
Simplified clinical procedures [2,6,20–24,26–30]	Purchasing and managing costs [2–5]
No more plaster casts [2,4,6,20,22,23,25–30]
Better communication with the dental technician [2,4,6,23,25–30]
Better communication with patients [2,4,6,20–24,26–32]

Table 2. The positive and negative features of commercially available IOS
Feature	Positive	Negative
Trueness	High	Low
Precision	High	Low
Resolution	High	Low
Need for opacization	Powder not needed	Powder needed
Scanning speed	Fast	Slow
Tip	Small/thin	Large/thick
In-colour images	Yes	No
System	Open (free. STL and. PLY files)	Closed (only proprietary files as output) or semi–closed (pay per. STL file)

Table 3. Clinical indications and contraindications of IOS
Field	Indication	Contraindication
Prosthodontics	Resin inlays/onlays [65,66]	Long-span fixed partial dentures and/or fixed full arches (6–8 elements) [7,8,35,37,39]
	Zirconia copings [67,68]	Long-span implant-supported fixed partial dentures and/or fixed full arches (6–8 implants) [39,117,118]
	Single-tooth restorations in lithium disilicate [69–74], zirconia [19,75–77], all ceramic [79–81]	Complete removable prostheses [57,121]
	Frameworks and fixed partial dentures in zirconia (4–5 elements) [82–87]
	Single-implant crowns [21,22,89–104]
	Implant bridges (4–5 implants) [104–113]
	Implant-supported bars (≤4 implants) [114–116]
	Posts and cores [123]
	Partial removable dentures [119,120]
	Digital smile design [122]
	Obturators [124,125]
Implantology	Guided implant surgery [126–130]
Orthodontics	Diagnosis and treatment planning [3,5,6,12,15,16,25,27,131,132]
	Aligners [3,132]
	Custom-made devices [3,132]
	The virtual patient [130]

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Intraoral Scanners in Dentistry: A Review of the Current Literature

Background

Tables

Tables

Tables

References

Authors and Disclosures

Authors and Disclosures

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