Atypical Occlusal Relationships — How to Inform the Lab Before Things Go Wrong

The patient presents with a posterior crossbite. You send the model to the lab—but fail to mention that this is the patient's normal, which you want to reproduce. The lab technician looks at the model, sees the crossbite, and thinks: "Scanning or preparation error—I'll fix it." The restoration arrives at your office. The patient sits, chews—and says: "You've changed my bite; now my TMJs hurt." The lab wanted to help. But without information in the prescription, they worked based on assumption. This is a communication problem, not a technical one. And it can be entirely avoided—with one sentence in the prescription.

Why a Model Alone Is Not Enough

A model is static. A patient lives dynamically. A model shows:

Tooth morphology
Tooth position in the arch
Spatial relationships

A model does not show:

The actual trajectory of mandibular movements—whether the patient chews evenly or predominantly on one side
Whether asymmetry is anatomical or a preparation error or something to be corrected
How long the patient has been functioning with this relationship (muscle привыкание)
What the patient expects—improvement or reproduction of the existing state
Connection to TMJ—whether occlusal relationships are stable or cause discomfort

A lab technician looking at a model in isolation faces the question: "Is this normal for this patient, or an error I need to correct?" Without an answer—they guess. And when they guess wrong, the patient sits in the chair feeling pain.

When Occlusal Relationships Are "Atypical"

Type of Relationship	Description	Extent of Problem	Lab Needs to Know
Anterior crossbite	Upper incisors occlude palatally BEHIND lower incisors (instead of in front).	Usually 1–4 anterior teeth.	Is this patient's anatomy or a preparation error? To reproduce or correct?
Posterior crossbite	Upper posterior teeth occlude LINGUALLY (internally) behind lower posterior teeth.	One or both sides, ranging from premolar to last molar.	Which side, which teeth, whether functional or structural, whether to reproduce.
Deep bite / overbite	Upper incisors overlap lower incisors >3–4 mm vertically.	Affects the entire anterior segment.	Increase / maintain / decrease? What are the patient's anatomical limits?
Unilateral Cusp-Fossa Relationship (Lack of Unilateral Support)	Patient primarily chews on one side—the other side is non-functional.	One side affected, the other side normal.	Which side is functional? What occlusal scheme to apply? Should chewing habits be changed?
Asymmetrical midline	Maxillary midline ≠ Mandibular midline (shift >2 mm).	Patient's entire perception (aesthetics) and occlusion.	Anatomical or error? Reproduce or correct to symmetry?

What the Lab Needs to Know—Beyond the Model

Anatomical or Pathological?

"Right posterior crossbite"—is this the patient's natural anatomy, or the result of poor preparation, bad scanning, or incorrect implant position? If the lab doesn't know, they might think it's an error—and try to "fix" it. The patient, for whom this was a natural state of function, suddenly feels a change and discomfort.

Information for the lab: "Right posterior crossbite—anatomical, patient accustomed for years, no reported problems. Please reproduce."

How long has the patient been functioning in this relationship?

A patient who has been chewing with a deep bite for 20 years has developed accustomed muscles, TMJs, and habits. Changing the relationship means discomfort and risk of TMJ inflammation.

Information: "Deep bite—patient functions without problems. No change in occlusal vertical dimension planned. Please reproduce."

What does the patient expect?

Do they want correction (if they feel discomfort) or reproduction of the existing state (because they are accustomed to it)?

Scenario A: "Crossbite—patient reports TMJ pain. We plan staged correction. For articulator work—consult before fabrication." Scenario B: "Crossbite—patient chews normally, no complaints. Please reproduce existing relationships."

How to Communicate—Prescription Template

In every lab prescription, when relationships are atypical, include:

Type of occlusal relationship—e.g., "right posterior crossbite," "deep overbite 5mm," "midline asymmetry 3mm"
Extent—which teeth, which side, how many units
Is it anatomical or an error—"anatomical (patient accustomed)" vs. "preparation error (requiring correction)"
Action for the lab—reproduce / correct / consult
Note for the patient—if there's a change (patient would need to adapt to a new occlusion)

FAQ—Practical Questions

Can the lab change a crossbite to normal in a single restoration?: Not entirely. Correcting a crossbite requires changing the occlusion of the entire arch, not just one crown. Existing relationships can be reproduced or corrected locally—but this requires prior discussion and planning (wax-up, temporaries).
How does a deep bite affect crown design?: The lab designs the crown considering vertical overlap. With a deep bite, anterior teeth have less space on the occlusal surface—this affects morphology, ceramic thickness, and chip risk. The deep bite must be known in advance.
Does midline asymmetry always require correction?: No. If it is anatomical and the patient feels comfortable—the lab should reproduce it. Correction makes sense only when the patient reports discomfort or desires aesthetic changes.
What if a patient has a crossbite and wants correction?: That's much more than one restoration. Changing occlusal relationships = changing the trajectory of mandibular movements, changing loads on muscles and TMJs. It requires a wax-up, staged planning (temporaries), and then the definitive restoration. The lab must be involved from the beginning.
Can I change occlusal relationships in an implant restoration?: Natural teeth can flex slightly under load. An implant cannot—it functions rigidly. Relationships must be ideal immediately. With atypical relationships, implant correction is more difficult and expensive. A wax-up before implant fabrication is mandatory.
How to check before sending if the prescription contains all information?: Read the prescription and answer the questions: 1) Is the occlusal relationship described? 2) Is it clear whether it's normal or an error? 3) What should the lab do—reproduce or correct? If any are missing, add them.