From Scan to Crown: The Laboratory Work Between the Files

The case arrives before design begins

A restoration is a replacement for missing tooth structure. A crown covers a prepared tooth, while a bridge spans a gap with a replacement tooth supported by neighboring teeth or implants. In a digital workflow, a scan supplies some of the shape information needed to make that work. We start the story at receipt because the laboratory must first determine whether the incoming record belongs to the intended case and describes the stage the dentist wants to restore.

The prescription sets out the requested work and material, with enough detail to identify the teeth involved. The laboratory checks the scan against those instructions and the accompanying bite record, which shows how upper and lower teeth meet. The general description of a dental laboratory places fabrication within this relationship with the clinic. Missing information can require clarification before design begins. A complete upload is not evidence that the clinical recording contains every surface needed for the job.

The working model needs inspection

An intraoral scan is an optical surface recording made inside the mouth. Its mesh, a surface built from connected small faces, may contain gaps or stray fragments. The laboratory examines the prepared tooth and its margin, meaning the boundary where the restoration is intended to meet the tooth. If that boundary is unclear, drawing a confident line on the screen cannot make it clinically certain. The dentist may need to review the recording or obtain another one after assessing the mouth.

The opposing teeth and their relationship to the working arch also require attention. An arch is the curved row of teeth in one jaw. Separate upper and lower files can be individually detailed yet incorrectly aligned. Our explanation of STL surface files describes why geometry alone does not carry all the case information. A physical model may be made for later checks, but that model inherits limitations in its source data. Agreement with a derived model does not independently prove agreement with the mouth.

Design sets relationships, not just outlines

Computer-aided design means using digital modeling tools to create the restoration's shape. A proposed crown needs an internal surface that relates to the prepared tooth and an external surface that relates to its neighbors. The designer accounts for space for the material used to secure it. Contact areas are the places where it meets adjacent teeth. Occlusion describes how the upper and lower teeth contact during closing or movement, and its digital representation depends on the bite information supplied.

Material requirements influence the shape that can be manufactured. A bridge also has connectors, the portions joining its replacement tooth to the supporting units, whose dimensions and form need attention. Automated suggestions can provide a starting design, but a person reviews the proposal against the prescription and available records. We do not treat a computer warning as a complete clinical assessment. Whether the planned crown or bridge is appropriate depends on an examination by a qualified dentist, with laboratory feedback informing the work.

Manufacturing follows the material

Milling removes material from a block or disc using cutting tools. The machine needs instructions describing where those tools will move, and the design must suit their access and shape. A narrow internal feature cannot be reproduced simply because it exists on screen. Some milled ceramics require further heating to develop their intended material condition. For certain materials, the workflow accounts for dimensional changes during that processing. The correct sequence depends on the selected material and the validated method used to work with it.

Printing takes an additive route, building an object from successive layers. The general account of 3D printing explains the distinction from removing material. In a dental laboratory, the printed object might be a working model or a pattern used in a later manufacturing step. Some restorations can be printed using materials intended for that use. A printer's presence therefore does not reveal how the final crown was made. A printed resin object may require cleaning and further curing, meaning additional hardening under controlled conditions.

Finishing brings the work back to the bench

After fabrication, a restoration may need its attachments removed and surfaces finished. Depending on the material, laboratory work can include polishing or applying ceramic color effects followed by heating. These operations can change appearance and must preserve the intended fit. We find this stage easy to overlook in a description centered on files. The digital design records an intended shape, while the finished object reflects the manufacturing process and subsequent handwork. Those are related records of different stages.

Laboratory checks examine the edge and contact areas where the available model or other verification method allows. Color is compared with the prescription and photographs, whose limitations we discuss in communicating tooth color. A laboratory can identify a visible defect or a mismatch with its working model, but it cannot complete every check that requires the patient. If the finished object differs from what was prescribed, the explanation and any agreed change belong with the case documentation.

Fitting creates the final clinical record

At fitting, the dentist evaluates the restoration in the mouth. That includes whether it seats as intended and how it relates to the surrounding tissues and opposing teeth. Color can appear different from its laboratory appearance because the viewing conditions and neighboring teeth are now present. An adjustment may be appropriate, or further laboratory work may be needed. The decision depends on the clinical examination. A completed manufacturing sequence does not guarantee that the restoration is ready to be secured without further assessment.

The final record connects the placed restoration to its material and tooth location. It can distinguish the accepted design from earlier versions and describe adjustments made during fitting. A design file should not silently stand in for a record of what was actually placed, especially if later changes altered the work. We see the most useful digital workflow as one that leaves these distinctions readable. The next dentist then has a basis for understanding the restoration without having to reconstruct its history from appearance alone.