Intraoral scanners have completely transformed modern dental practices in recent years.1 But while a practice might find the decision to purchase an intraoral scanner to be a straightforward one, the decision around which intraoral scanner to choose can feel considerably more complicated.
An intraoral scanner is a handheld device used to create a digital impression of the oral cavity by capturing a series of images of the dentition and soft tissue. These images are then processed using advanced scanning software to generate a 3D model.
When assessing which intraoral scanner is the right fit for a dental practice, several factors should be taken into consideration including types of treatment and services offered, patient volume, patient demographics and practice demands.
There is no one-size-fits-all intraoral scanner as each dental practice has a unique ecosystem in which their chosen scanner should fit within and enhance.
Accuracy of intraoral scanners: the sum of trueness and precision
When assessing the difference between intraoral scanners, one of the more significant differences is the accuracy of the digital impression the scanner generates. An intraoral scanner’s accuracy is dependent on two important elements: trueness and precision.2
Trueness refers to the ability of a measurement to match the actual value of the quantity being measured.
Precision refers to the consistency with which that measurement can generate identical outcomes. i.e. Are these results repeatable?
Several factors contribute to variances in accuracy including the scanner’s algorithm and the operator’s scanning strategy.3 One of the major variables, however, is the different ways in which the digital impression is generated and stored. In other words, the use of stereolithography (STL) file format as opposed to Wavefront object (OBJ) or Polygon File Format (PLY) file formats.4
- STL file format produces a 3D model of a scanned object by constructing an approximate mesh structure of that object. Due to its approximate nature, this mesh can contain deficiencies in trueness—an important factor to consider when scanning something as crucial as a finish line for a fixed restoration, for example.5
However, if a practice has a high volume of prosthodontic cases like single-unit crowns and minor bridges spanning one to four units, an STL digital impression might be an adequate choice as it is similar in trueness to conventional impressions. - OBJ and PLY file formats produce digital models by constructing a precise mesh, allowing for a more accurate and higher quality digital model. When comparing the two, even the highest-resolution STL scan remains considerably lower resolution than the lowest quality scan using OBJ and PLY file formats.4
Furthermore, OBJ and PLY scans include details about the color and surface texture of a scanned object. This capability allows for highly accurate, multicolor 3D printing, a feat not possible with the monochromatic STL file format.
How fast an intraoral scanner can acquire a digital impression
Speed holds significant importance for dentists since a faster scan acquisition directly translates into valuable time savings for the clinician. The following factors will largely determine the speed with which a scanner acquires a digital impression.6
- Frame rate: The scanner’s built-in camera can capture hundreds of pictures per second in the mouth. A higher frame rate (more frames per second) contributes to a faster scan acquisition.
However, more images extend the time required for point cloud extraction. Therefore, raising the frame rate alone doesn’t necessarily lead to a direct increase in overall scan speed. There are other factors to consider. - Image format: The image format determines the number of extracted point clouds. A greater aspect ratio corresponds to a higher number of point clouds being extracted at a faster rate, accelerating scan speed.
- Algorithm: The better a scanner’s algorithm, the quicker the model stitching and fusion, leading to faster and smoother scanning.6
Closed vs open systems
The primary distinction between an open-architecture system and a closed-architecture system lies within their ability to integrate with tools from outside manufacturers as well as communicate with external partners.
In essence, a closed system operates exclusively within its proprietary framework and will not integrate with any tools outside that framework. An open architecture system offers the flexibility to integrate and communicate with external vendors (i.e. the hardware, software and partners a practice already uses and likes).
Open systems could facilitate more collaborative workflows and give a practice the flexibility to adapt their scanner to the processes already in place as opposed to the other way around.
Scanner tip sterilization and disinfection
According to the Centers for Disease Control, steam sterilization (autoclave), is the most widely used and dependable of all disinfection methods available.7
Certain intraoral scanners feature detachable tips that can be autoclaved in this way and used for over 100 cycles, depending on the manufacturer.
Some intraoral scanners, however, lack detachable tips and require disinfection via cold sterilization or surface disinfectant wipes.8-9
This could be extremely important for practices with a high patient volume or immunocompromised patients, especially in the COVID-19 era where disease transmission is a genuine concern for those in the clinical environment.10
Ergonomic design
The ergonomics and device features of a scanner are also important to keep in mind, especially when considering a practice’s patient population.
Pediatric patients, for instance, may require an intraoral scanner with a smaller tip size.11 Some intraoral scanners with detachable tips offer a range of tip sizes, giving clinicians the opportunity to adapt their scanner to suit each distinct patient situation.
Additionally, the weight of a scanner and the way it balances in one’s hand can be important when considering the stamina and comfort of your operators.
Furthermore, factors such as antifog and wireless capabilities play an important role when evaluating intraoral scanners as patient volume, need for portability and office configuration should all be considered.
Scanner calibration
Some intraoral scanners need regular maintenance and calibration to function properly while others require no ongoing calibration.12
For intraoral scanners which require calibration for operation, the frequency will depend on how much that scanner is used, particularly if it is moved from chair to chair throughout the dental facility.
Some manufacturers use a manual calibration tool which requires an operator to physically connect the intraoral scanner to a unit.13-14 Some offer autocalibration through a server and others, still, have designed intraoral scanners that require no ongoing calibration for regular use.
Automating the calibration process and better yet, removing the process altogether, could significantly streamline processes for high-volume dental practices or clinics where the intraoral scanner is moved frequently from room to room.
Training and continued customer service
In addition to the fundamental features and capabilities of the scanning device, it is important to consider aspects related to training, service and repairs.
Depending on the manufacturer, in-office training, hands-on courses or virtual training may be offered along with the purchase of a scanner. A practice must evaluate what type of training they believe will work best for their schedule and staff.
Hardware and/or software problems can also arise in any system. Being aware of who is responsible for the servicing of a practice’s equipment and the extent of customer support available in times of assistance is crucial.
The optimal intraoral scanner
Defining the optimal intraoral scanner is not as straightforward as it might seem at the onset. Clinicians need to evaluate their objectives for purchasing an intraoral scanner and consider the treatments they offer as well as the characteristics of their patient population.
Once armed with this information, they can identify the intraoral scanner model that will work well for their practice.
Get a free consultation with your local IOS expert around how to advance your practice with a DEXIS™ intraoral scanner.