Intraoral scanners – challenges yet to be overcome
Featured Products Promotional FeaturesPosted by: Dental Design 12th February 2023
Despite the focus on intraoral scanners in dentistry, contemporary research[i] estimates that only 5-10% of dentists in the UK have purchased one for themselves. There are several reasons why these solutions may not yet be widely utilised, including both the personal preferences of clinicians and technical abilities of the devices. With regards to the latter, both dentists and product developers are looking for ways to overcome the challenges facing digital impression acquisition, so that they can ensure provision of the best possible care to patients.
So, what are some of the most common difficulties associated with modern intraoral scanners?
Accuracy
The goal of all dental impressions, whether taken using analogue or digital methods, is accuracy. This is defined by one study[ii] as the combination of “precision” and “trueness”. Factors that have been found to affect the accuracy of digital impressions include the type of scanner, the technique used and also the environmental conditions in which the scan was taken, including the light level in the practice.
There is a growing body of research looking at trueness and precision of digital impressions compared to analogue workflows. Though more evidence is needed, Lee et al[iii] found that gypsum models from analogue impressions were more detailed than milled models from digital impressions in secondary anatomical areas like grooves and fossae, by a statistically significant margin. Research[iv] has also suggested that digital impressions are less effective for replicating subgingival marginal detail, or juxtagingival margins where there is bleeding, for example. The optical-based technology can’t adequately capture data from below the gumline, impacting the accuracy of the impression. As such, intraoral scanners are not generally recommended where subgingival margins are present, as was found by Ferrari Cagidiaco et al.[v]
When delivering implant therapy, difficulties have been reported with obtaining an accurate scan of the full arch when using digital impression methods. Waldecker et al[vi] found that larger scan volumes of more than one quadrant resulted in increased scatter and decreased accuracy, making digital impressions inappropriate in these cases. The same study suggested that vertical and tooth axis deviations are significantly greater with digital impressions compared to analogue techniques.
Learning curve
As with any new piece of equipment, there is a learning curve associated with digital impressions. All clinicians have been taught analogue impression techniques during undergraduate training, so naturally have had time to refine their capabilities. Only those newer to the profession will have been exposed to digital impressions from an early stage in their careers. Digital impressions require new skills and a different approach to obtain precise detail replication. As such, clinicians must be aware of the differences in technique and undergo user training in order to familiarise themselves with the digital workflow, as well as the specific scanner they choose to use. Operator experience may also influence accuracy of the impression obtained, although the research is still contradictory in this area.
Purchase price
As with any new equipment, a key aspect that clinicians need to consider should they wish to introduce an intraoral scanner into their workplace is the financial cost. Though some individuals can justify the investment in technology by the results they achieve and the patient experience they deliver, others will struggle with the initial outlay. It can take a couple of years to earn back the money that a scanner costs, so it’s important for professionals to assess their needs for digital impressions and manage their budgets accordingly.
Further development
Aside from the aforementioned hurdles, other possible challenges with digital impressions that have been highlighted in some of the literature will need more research to confirm. For example, one paper[vii] suggested that intraoral scanners raise surface temperature in the mouth, which could lead to tooth sensitivity. The researchers postulated that this would be most relevant for patients with cervical cavities and already sensitive dentine.
It is also important to note that there are numerous models available on the market and that these vary substantially in quality. The International Team for Implantology (ITI)[viii] suggests that some solutions are more technique sensitive than others, implying that user experience and technique preferences should be considered when choosing a device to implement in practice. Other considerations for product selection include available payment options, access to technical support and user training.
Ultimately, the potential advantages of a completely digital workflow are likely to continue driving demand for intraoral scanners in the coming years. Over time, the technology may well be refined to provide the new gold standard for dental impressions. For now, further development is needed before the profession can confidently replace existing analogue techniques across the full spectrum of clinical indications. Trusted, widely available analogue impressions will likely remain the first choice until such a time that digital technology can match or surpass the level of accuracy achievable in this way.
Author: Alyn MorganPresident – Elect of the British Endodontic Society
Alyn Morgan graduated from Leeds Dental School in 1995 and worked in general dental practice for 12 years. He undertook an MSc in Endodontics at the Eastman Dental Institute which was awarded with Distinction in 2009. He has worked as a specialist in endodontic practice for 10 years at U Dentistry in Ilkley and has been a Senior Clinical Teaching Fellow in Endodontics at both the Eastman and Leeds Dental Institutes. He is currently Head of Endodontic Teaching at Leeds where he teaches undergraduates, postgraduates and hands-on courses for GDPs. He is President-elect of the British Endodontic Society
[i] Kustrzycka D, Marschang T, Mikulewicz M, Grzebieluch W. Comparison of the Accuracy of 3D Images Obtained fromDifferent Types of Scanners: A Systematic Review. J Healthc Eng. 2020 Dec 14;2020:8854204. doi: 10.1155/2020/8854204. PMID: 33414902; PMCID: PMC7752290.
[ii] Sanda, M., Miyoshi, K. & Baba, K. Trueness and precision of digital implant impressions by intraoral scanners: a literature review. Int J Implant Dent 7, 97 (2021). https://doi.org/10.1186/s40729-021-00352-9
[iii] Lee SJ, Betensky RA, Gianneschi GE, Gallucci GO. Accuracy of digital versus conventional implant impressions. Clin Oral Implants Res. 2015 Jun;26(6):715-9. doi: 10.1111/clr.12375. Epub 2014 Apr 10. PMID: 24720423; PMCID: PMC4428303.
[iv] Mangano FG, Margiani B, Solop I, Latuta N, Admakin O. An Experimental Strategy for Capturing the Margins of Prepared Single Teeth with an Intraoral Scanner: A Prospective Clinical Study on 30 Patients. Int J Environ Res Public Health. 2020 Jan 7;17(2):392. doi: 10.3390/ijerph17020392. PMID: 31936096; PMCID: PMC7013902.
[v] Ferrari Cagidiaco E, Zarone F, Discepoli N, Joda T, Ferrari M. Analysis of The Reproducibility of Subgingival Vertical Margins Using Intraoral Optical Scanning (IOS): A Randomized Controlled Pilot Trial. J Clin Med. 2021 Mar 1;10(5):941. doi: 10.3390/jcm10050941. PMID: 33804358; PMCID: PMC7957624.
[vi] Waldecker, M., Rues, S., Awounvo Awounvo, J.S. et al. In vitro accuracy of digital and conventional impressions in the partially edentulous maxilla. Clin Oral Invest 26, 6491–6502 (2022). https://doi.org/10.1007/s00784-022-04598-4
[vii] Natongkham P, Banthitkhunanon P, Wanachantararak S. Dentine sensitivity caused by illumination of intraoral scanner and light curing unit. J Clin Exp Dent. 2022 May 1;14(5):e420-e425. doi: 10.4317/jced.59251. PMID: 35582349; PMCID: PMC9094722.
[viii] Cutts R. Digital dentistry – using intraoral scanning. ITI Blog. 2021. https://blog.iti.org/clinical-insights/digital-restorative-dentistry-using-intraoral-scanners/ [Accessed December 2022]
