Intraoral Scanner Vs Impression: A Study to Test All Advantages (2023)

‍Table of Contents:

1. Intraoral Scanner vs Impressions: a quick overview
2. How it works and Materials  
3. Advantages
4. Disadvantages 
5. Use Cases and Trends
6. Eon Aligner Case Study 
7. FAQ

Intraoral Scanner vs Impressions: A Quick Overview

The world of orthodontics and dental prosthetics is continuously evolving and progressing to ensure patient satisfaction. The transition from traditional impressions to modern digital dental impressions has successfully created a paradigm shift. Materials such as alginate and silicone provide dentists with ideal impressions, however, they also impose various challenges, such as being uncomfortable for patients and extremely skill-sensitive. 

Patient’s discomfort with conventional impressions may come from the apprehension of gag reflexes or the invasive nature of the procedure. Additionally, conventional impressions could be prone to distortions, leading to discrepancies in the final prosthetic work. The concept of intraoral scans emerged to address these issues and enhance the precision of orthodontic and prosthetic treatments (1). 

How it works and materials  

Digital Impressions (DIs)

Digital 3-D dental impressions provide excellent precision and patient comfort, greatly reducing the anxiety associated with traditional impressions. In the field of orthodontics which often involves young patients, the use of digital impressions allows practitioners to save time and reduce costs. 

Digital impressions are taken with the help of intra-oral scanners. They operate on the principle of capturing precise 3D images of a patient's oral structures.

To capture these detailed impressions, a few essential materials come into play. Intraoral orthodontic scanners utilise a wand-like device equipped with a small camera, which captures images at a rapid rate, thereby creating a seamless 3D model. These scanners may often require reflective powder or a contrast medium to enhance image quality, particularly for challenging cases or reflective surfaces (2). 

Intraoral Scanners: 

Scanners are digital intraoral imaging devices and consist of data acquisition systems of the tooth surface in three dimensions. In a typical workflow, the scanner emits a safe light source, which interacts with the oral tissues. Depending on the type of scanner used, the light source could be laser-based, structured light, or confocal microscopy. These technologies work in unison to record the contours of the teeth and soft tissues with remarkable precision (3).

Types of Intraoral Scanners:

Laser-based Scanners

These scanners use laser light to measure the distance to the tooth surfaces within the oral cavity. They are highly accurate and efficient, making them a popular choice among practitioners.

Structured Light Scanners

This type projects a pattern of structured light onto the oral structures and captures distortions to create a 3D image. They are known for their speed and precision.

Confocal Microscopy Scanners

These scanners employ a pinpoint light source and measure the reflections to construct a 3D image. They are handy for capturing fine details.

Ultrasound Scanners

Ultrasound scanners use high-frequency sound waves to create a 3D representation of the oral structures. While less common, they offer their unique advantages.

Traditional Impressions

Conventional impressions involve the use of materials such as alginate or silicone putty with light body to capture a patient's dental structure. Typically, practitioners place a tray filled with impression material into the patient's mouth. This technique, while tried and tested, has inherent challenges. 

The method itself is highly reliant on the clinician's skills, making it prone to errors. The need for a precise, undistorted impression adds complexity to the process. Furthermore, alginate impressions need to be poured into a cast immediately to avoid dimensional changes. Traditional dental impressions, while fundamental, often result in a less comfortable experience for the patient and can be time-consuming for orthodontists (4). 

Advantages

Digital Impressions

Enhanced Detail and Accuracy:

In the debate of intraoral scanners vs traditional impressions, accurate detailing, structure in tooth morphology and dimension stability are offered by digital impressions. Unlike putty impressions, digital ones present a distortion-free method of replication of intra-oral structures while eliminating the need to depend on the dexterity of the practitioner. The inherent risk of human error is minimized and the post-impression trimming and assembly stages are eliminated. Moreover, 3-D digital impressions can be viewed from multiple angles therefore allowing orthodontists to reach a more comprehensive treatment plan. (5).

Enhanced Patient Comfort:

The golden pillar of digital impressions remains patient care. The slim intraoral scanners ensure that the process is faster and less tedious for the patient. Traditional impressions require patients to sit still while the practitioner hovers over them whilst pushing the trays inside the mouth and carrying out certain soft tissue movements. In contrast, intraoral scanners are inherently less intrusive and lay a greater emphasis on patient comfort which in turn generates better patient compliance and satisfaction. 

Effortless Data Sharing:

A comprehensive treatment plan often requires an interdisciplinary approach that requires sharing of patient data. The digital format shines in this era and enables practitioners to share data seamlessly through secure online platforms. Digital dental impressions can be shared in the form of STL files with a fellow practitioner, a specialist for a consultation or a lab technician while ensuring that the impression originally taken will remain exactly the same when viewed by the other party. This thoroughly streamlines the entire process and ensures a smooth decision-making process. 

Eco-Friendly Practicum:

Talking from an ecological standpoint, digital impressions are a more eco-conscious choice that reduces waste. Digital 3-D impressions are environmentally more sustainable and completely reduce the physical waste created by traditional impressions. This not only minimises environmental impact but also improves data management while eliminating the need for physical storage infrastructure. 

Traditional Impressions 

Cost-Effective:

Traditional impressions are more cost-effective and hence make them more accessible for a broader range of patients and dental practices. The materials required for traditional impressions are cheaper and might be a more affordable option for practitioners who are just setting up a clinic. 

Adaptability:

Traditional impressions remain useful in cases where patients might have conditions, such as excessive salivation, that can complicate the use of intraoral scan

Disadvantages 

Digital Impressions 

Initial Investment:

The implementation of a digital system requires a high baseline investment for the equipment and training. This can pose a substantial financial burden for smaller practices

Intraoral Camera Size:

Some patients, particularly those with limited mouth opening, may find the size of intraoral cameras uncomfortable, making the scanning process challenging (7).

Traditional Impressions 

Patient Discomfort:

Traditional impressions have stood the test of time but are infamous for the discomfort caused to patients. Experiencing gag reflex and overall unease during the entire procedure is uncomfortable for patients. This is especially seen with younger patients that often require orthodontic treatment. Creating a fear-inducing experience at the start of the treatment itself can lower patient compliance and affect their willingness to seek dental care. 

Inaccuracies and Distortions:

Conventional impressions are prone to distortions and inaccuracies due to factors such as inadequate material mixing and the potential for deformation during setting. These limitations can compromise the precision of diagnostic models and the efficacy of orthodontic appliances or prosthetic restorations.

Logistical Complexities:

The storage and retrieval of physical impressions pose basic logistical complexities. The need to store physical moulds not only consumes space but also takes time to reach labs. This hinders the efficacy of patient care and workflow in a dental practice (5).

Differing trends between Intraoral scanners vs traditional impressions

Several studies have highlighted that the kind of impression modality used depends on the type of therapy and orthodontic devices used during the treatment (8). 

Saccomanno et al in 2022 reported that conventional impressions are still used for fixed devices, while digital impressions are more adapted for orthodontic customised devices and therapies with clear aligners, which are very widespread among adult patients. 

Similarly, Ciucciù et al showed that the digital impression is very effective in reducing anxiety and nausea; (8). 

A prominent disadvantage of using intraoral scanners is the learning curve required to understand and use the technology with ease. Zitzmann et al. analysed both digital and conventional impression techniques. Without a doubt, no experienced dental student found a digital tool easier than conventional impression techniques (10). 

On the other hand, the advantages of digital impressions are undeniable and have been proven by studies by Joda et Bragger that showed patients preferred digital technique, particularly because of their efficiency in terms of time (11). Moreover, Gjelvold et al. concluded that the digital technique was more efficient and convenient than an analogical, conventional one (12). 

Case Study 

General Overview 

Magano A et al conducted a study that evaluated the patients’ preferences and attitudes towards the digital impression technique compared to the conventional impression technique, in young orthodontic patients. The null hypothesis was that there is no difference in patients’ preference and treatment comfort between the conventional and digital impression techniques (13).

Methodology and Resources

The study was conducted with 30 subjects with an equal division of males and females. The age group of the subjects ranged from 7 to 16 years of age and none of the patients presented with any prior experience of conventional or digital impressions. All the subjects underwent impression-taking methodologies to obtain orthodontic models. Conventional impressions were taken using alginate impression material and acceptability and perceptions of subjects were recorded immediately after the procedure using a standardised questionnaire.

A digital impression of both arches was obtained 15 days later using an intraoral scanner. Patients’ attitude and discomfort was tested immediately after the impression using a VAS (Visual Analogue Scale). The perceived source of stress was assessed using a State anxiety scale (S-scale).

Discussion

In this clinical trial, digital impressions were favoured by patients in terms of comfort and overall acceptance, leading to the rejection of the null hypothesis.

The study primarily focused on evaluating the stress perceptions and overall acceptability of two impression techniques. The results indicated statistically significant differences in overall impression time, attributed to the rapid setting time of the alginate material. All parameters related to patients' acceptability and comfort favoured digital impression systems over conventional techniques. 

Gag reflex and breathing difficulty showed significant differences, potentially highlighting the benefit of digital impressions in overcoming these issues. However, it's essential to note that not all digital impression systems may yield the same results.

Results

The study had the following results:

- Digital impressions were significantly more accepted by patients than conventional ones.

- Intraoral scanners excelled in terms of comfort, gag reflex, and breathing difficulty.

- Both techniques showed no significant difference in terms of stress (State anxiety scale).

Conclusion

In summary, the advent of intraoral scanners has revolutionised the field of dental impressions. This digital technology offers superior patient care and addresses issues such as gag reflex and breathing difficulty. While stress levels remained comparable, the overall acceptance of digital impressions significantly surpasses that of conventional methods. The transition to intraoral orthodontic scanners indicates a progressive shift in modern dentistry, heralding a more patient-centric and efficient approach.