Patient Records, Impressions, and Intraoral Scanning
What this domain tests
Record sets, photographic and cephalometric technique, alginate and vinyl polysiloxane handling, digital scanning workflow, and the documentation that makes records legally and clinically usable.
Record sets
- Extraoral photos: frontal at rest, frontal smile, profile.
- Intraoral photos: right buccal, frontal, left buccal, upper occlusal, lower occlusal, plus overjet and overbite views with retractors and mirrors.
- Radiographs: panoramic, lateral cephalometric, bitewings for caries, periapical or CBCT for impacted teeth and anchorage planning.
Cephalometric and radiation technique
Position with the Frankfort plane horizontal, ear rods in the porion, teeth in occlusion, lips relaxed. Apply ALARA: lead apron with thyroid collar, beam collimation, and no repeat exposures without cause.
Impressions
Alginate is an irreversible hydrocolloid: measure powder and water per manufacturer, mix 45–60 seconds, seat in a perforated tray, hold until set. Warm water accelerates set, cold water retards it. Alginate loses accuracy through syneresis if it dries and imbibition if it soaks; pour promptly or store briefly in a sealed bag with a damp paper towel. Vinyl polysiloxane is dimensionally stable for days, needs tray adhesive, and can be disinfected and shipped.
Intraoral scanning
Retract and dry the field - saliva creates holes and ghost images. Scan occlusal surfaces first, then buccal and lingual, keeping the tip a few millimetres from the teeth and moving steadily. Trim, capture the bite in maximum intercuspation with a buccal scan, verify no holes or doubled surfaces, and export STL or PLY through a HIPAA-compliant channel.
Labeling and disinfection
Every model, scan, and photo is identified with patient name, date, and operator. Rinse and disinfect impressions with an intermediate-level disinfectant per manufacturer contact time before pouring or shipping; disinfect scans are digital and require no chemical step, but the file still carries protected health information.
Worked example
An alginate impression sits on the counter for two hours before pouring. Reasoning: the material has begun to lose water and distort, so the model will not match the mouth. Discard and retake, then pour within the manufacturer's window, or store it sealed and damp. Document the retake - insurers and clinicians both need to know why a second set exists.
Traps that cost marks
Pouring dried alginate; skipping tray adhesive for VPS; scanning a wet field; taking photos with retractors not fully seated; and forgetting the thyroid collar.