One of the greatest advantages of practicing dentistry in this day and age is the abundance of technology available at our fingertips. The key to an efficient workflow that will yield consistent results is to develop the skills and systems needed to acquire high-quality digital models. This complete intraoral scanning guide can serve as a foundation of steps to understand as you utilize scanners for 3D scanning.
An example of critical use of digital dentistry, such as cad/cam software, can take place in staging clear aligners for patients. In a process where such fine details as tight spaces and gaps need to be well documented for a successful treatment, it can be stressful to ensure that the 3D scans your team produces are consistent. The following factors are imperative to regard in order to achieve 3D models that will yield high-accuracy printed parts.
Factors impacting the quality of an intraoral scan
Within intraoral scanning, there are two main factors that take precedence during the process: time and quality. The following factors are essential in taking good quality scans quickly.
1. Scanning path
Start from the occlusal surfaces of the posterior teeth in a rock and roll motion to achieve good quality scans quickly, thus reducing dimensional inaccuracies. The rock and roll motion of the upper and lower anterior teeth is critical to avoid steps on the incisal edges of the front teeth.
2. Clean teeth
All patients should brush immediately prior to a scan. Dental plaque or food in the patient’s mouth will impact the quality of the scan.
3. Second and third molars
It is important to leave at least 1 mm of gingival tissue around the last tooth of each arch. Any excess soft tissue should be removed while scanning these areas.
4. Dry surfaces
Use air to dry out surfaces of the teeth prior to scanning. Bubbles on scans will create changes in segmenting teeth and will adversely affect the quality of a scan.
5. Interproximal area
It is important to obtain both the mesial and distal aspects of all the teeth, hence the importance of following a loop path around each arch. Areas that are often missed are mesial and distal surfaces of the upper premolars. Patients with gingival recession and bone loss need more time to scan accurately.
6. Crowding and missing teeth
Move the scanning wand in all directions to acquire the accurate edge of the teeth in crowded patients. The scanner can patch these areas which result in inaccurate aligner adaptability. The mesial and distal surface area of endentous parts of the arch needs more time to scan accurately.
7. Black triangles and spaces
Minor spaces (<0.1 mm) and black triangles are often not captured by the scanners. This information has to be charted in the patient treatment card. We encourage taking photos or videos to document such areas for the orthodontist and team.
8. Clean the model prior to submission
If available, use the scanner software to trim the edges of the model for a cleaner finish.
Storage of the .stl/.ply models
Take the time to discuss with your team and define a protocol to decide where you will store the models. The benefit of 3D digital models is that model boxes and storage shelves will be obsolete. Your new model storage unit will most likely be on a cloud or hard drive. Other options are to use a physical hard drive or software such as EasyRx or Google Suite’s Google Drive.
On top of determining your storage, consider how you will have a backup system, either physical or cloud. If you plan to use a physical hard drive, you might want to establish a rotation system of a weekly backup download.
The last issue to tackle is HIPAA. As always, we want to ensure that our patients’ data are safe and the information is secure. We advise looking into ways to certify that your information remains secure, such as signing a Business Associate Agreement (BAA).
Software to minimally manipulate the .stl models
On top of using the build-in design software to clean the models, you can also use external software to prepare 3D models for aligners, occlusal guards, and other dental appliances. Meshmixer, Blender, Blender for Dental, and D3Tool are accessible software with existing tutorials.