CIT Dental Laboratory Communication & Implant Prosthetics Workflow — Questions and Answers
Question 1: Which information is most critical to include on a laboratory prescription for an implant-supported crown that is NOT required for a conventional crown on a natural tooth?
- Patient's full name and date of birth
- The implant system brand, implant platform size, and connection type (e.g., internal hex, conical) (Correct answer)
- The shade and material requested
- The dentist's license number and practice address
Correct answer: The implant system brand, implant platform size, and connection type (e.g., internal hex, conical)
Unlike a crown on a prepared tooth, an implant crown must attach to a specific implant via a precisely engineered abutment. The lab must know the exact implant brand, platform diameter, and connection geometry to select a compatible abutment. Using the wrong connection type will result in a restoration that does not fit the implant.
Question 2: What is a 'master cast with an implant analog' used for in the traditional laboratory workflow?
- It is a radiographic model used to plan CBCT-guided surgery
- It is a stone model containing a replica of the implant that allows the lab to fabricate a restoration as if working directly on the patient's implant (Correct answer)
- It is a provisional model used only for shade matching
- It is a diagnostic wax-up cast made before implant placement
Correct answer: It is a stone model containing a replica of the implant that allows the lab to fabricate a restoration as if working directly on the patient's implant
An implant analog is a metal replica of the implant fixture that is placed in the impression before it is poured in stone. The resulting master cast has the analog in the exact position and orientation of the patient's implant, allowing the dental technician to seat, adjust, and fabricate the abutment and crown directly on the lab model.
Question 3: Which shade guide system is most widely used in dental laboratories for selecting the color of implant-supported ceramic crowns to match natural teeth?
- Munsell color system
- VITA Classical (A1-D4) shade guide (Correct answer)
- RAL industrial color standards
- Pantone color matching system
Correct answer: VITA Classical (A1-D4) shade guide
The VITA Classical shade guide (with shades A1–A4, B1–B4, C1–C4, D2–D4) is the dental industry standard and the most universally understood communication tool between clinicians and dental laboratories worldwide. Specifying a VITA shade ensures the lab and clinician are using the same reference system.
Question 4: When returning a laboratory case that does not fit or requires modification, which document should accompany the case to clearly communicate the needed adjustments?
- A new patient health history form
- A remount lab prescription detailing the specific issue, proposed correction, and return deadline (Correct answer)
- An insurance pre-authorization form
- A HIPAA privacy notice signed by the patient
Correct answer: A remount lab prescription detailing the specific issue, proposed correction, and return deadline
A remount or remake prescription clearly identifies the problem (e.g., 'open contact mesially,' 'occlusion is high by 0.5 mm,' 'shade too dark'), specifies the correction, and includes the return date needed to meet the patient's appointment. Without written documentation, verbal descriptions are easily misunderstood and errors recur.
Question 5: A dental laboratory requests a 'pick-up impression' for an implant case. What does this technique involve?
- A bite registration taken with the provisional crown in place
- An open-tray impression where the impression coping is captured within the impression material and removed with the tray, maintaining the coping's exact position (Correct answer)
- A standard closed-tray impression of the final crown for verification
- A periapical radiograph taken to confirm implant position before lab fabrication
Correct answer: An open-tray impression where the impression coping is captured within the impression material and removed with the tray, maintaining the coping's exact position
In the open-tray (pick-up) impression technique, the impression coping is screwed into the implant and a custom tray with an access hole is used. The coping stays locked in the impression material when the tray is removed, precisely recording the implant's position. The analog is then screwed onto the captured coping to create the master cast.
Question 6: What is the purpose of a 'diagnostic wax-up' that is sent to the dental laboratory before implant placement?
- To test the strength of the dental wax under occlusal loading
- To visualize and communicate the planned final restoration shape, size, and position to guide surgery and prosthetic planning (Correct answer)
- To create a temporary filling material for the edentulous space
- To record the patient's existing bite before any treatment begins
Correct answer: To visualize and communicate the planned final restoration shape, size, and position to guide surgery and prosthetic planning
A diagnostic wax-up is a 3D prototype of the planned final restorations built in wax on study models. It communicates the intended esthetic and functional outcome to the surgeon, prosthodontist, and patient, and can be used to fabricate a radiographic or surgical guide that positions implants in the ideal prosthetic location (prosthetically-driven implant placement).
CIT Dental Laboratory Communication & Implant Prosthetics Workflow
Which information is most critical to include on a laboratory prescription for an implant-supported crown that is NOT required for a conventional crown on a natural tooth?