Occlusal Considerations.
Occlusion is the most frequent reason a well-made restoration needs work at the chair, and most of the difficulty is decided by the records rather than by the design.
Conform or reorganize — decide explicitly
Almost every restorative case takes one of two approaches. The conformative approach accepts the patient's existing occlusal scheme and builds the restoration into it, aiming to change nothing. The reorganized approach establishes a new scheme, usually at a defined jaw relationship and often at an altered vertical dimension.
For a single unit in an otherwise stable dentition, conformative is almost always correct and the objective is simply not to disturb anything. For extensive work — multiple quadrants, a full arch, a case where the existing scheme is part of the problem — reorganizing may be unavoidable.
The decision has to be made and communicated before fabrication. A case sent without saying which approach applies is a case where the laboratory assumes conformative, which is right most of the time and expensively wrong when it is not.
Where centric contacts should sit
A restoration in maximum intercuspation should carry contact comparable to the teeth around it — not lighter, which throws load onto the neighbours, and not heavier, which is the usual complaint at delivery.
The contacts themselves should sit on cusp tips against opposing fossae or marginal ridges, directed as close to the long axis of the tooth as the anatomy allows. Contacts on inclines produce lateral vectors, which are what the periodontium and the restoration both tolerate least.
Whether the scheme is cusp-to-fossa or tripodized matters less than whether the contacts are stable and axially directed. What matters most is that they match what the patient already has.
Excursions are where restorations fail
A restoration correct in intercuspation and interfering in excursion will produce sensitivity, fracture, wear or all three, and the interference is frequently missed because it is checked last if at all.
In lateral movement, the working side should be guided by whatever guides the patient already — canine, group function, or some combination — and the non-working side should be free. Non-working interferences are the most damaging because the vector is unfavourable and the patient's muscles are poorly positioned to protect against it.
Protrusive interference on posterior teeth is the other recurring fault, and it is what makes anterior restorations chip and posterior restorations wear.
What determines whether the laboratory can help
The bite record is the whole basis of occlusal design, and an inaccurate one cannot be compensated for by any amount of care afterwards.
For a single unit with stable surrounding contacts, a well-taken interocclusal record and complete adjacent teeth are usually sufficient. For anything more extensive, mounted casts are worth the additional step, because a hand-held relationship does not reproduce arcs of closure or excursive movement.
Where the case involves anterior guidance, a facebow record lets the articulator approximate the patient's condylar geometry rather than an average, and the difference shows most in how excursive contacts behave. It is not needed for every crown, and it is worth it on cases where guidance is being built or restored.
Where the patient has no stable position
Some patients have no reproducible maximum intercuspation — extensive wear, multiple missing units, an unstable existing prosthesis, or a scheme that has collapsed over time.
Recording a bite in that situation captures one arbitrary position among many, and a restoration built to it will be wrong as soon as the patient closes differently. This is the point at which the case needs a defined jaw relationship established deliberately, usually through a provisional phase.
If this describes the case, say so on the prescription. It changes how the case is mounted and what the laboratory should be building to.
Multiple units change the problem
Restoring several adjacent teeth removes the reference the laboratory would otherwise have used. With a single crown, the surrounding contacts define what correct looks like. With four, that definition is gone and the occlusal scheme is being designed rather than matched.
This is where staging helps: restoring in segments so a stable reference always remains, or working through a provisional phase where the scheme is established, tested and then copied.
A case restoring a whole quadrant in one step, sent conformatively with a single bite record, is asking the laboratory to invent an occlusal scheme and hope the patient accepts it.
Articulators reproduce some things and not others
A semi-adjustable articulator approximates condylar guidance from recorded or average values and reproduces opening and excursive movement well enough for most restorative work. It does not reproduce the neuromuscular envelope, tissue resilience, or the patient's actual pattern of function.
That gap explains a recurring experience: a case that articulates perfectly and needs adjustment in the mouth. The articulator was not wrong; it was reproducing geometry rather than behaviour.
The implication is not to distrust mounted casts but to expect some refinement, and to design with a small margin where excursive contacts are concerned. A restoration built exactly to an articulator's excursive path is more likely to interfere than one built slightly clear of it.
What to state on the prescription
Whether the case is conformative or reorganized. What guides the patient in excursion. Whether the intercuspal position is stable and reproducible. Whether the vertical dimension is being changed. What the antagonist is, including whether it is natural, restored or prosthetic.
Five lines at most, and between them they determine almost everything about how the occlusal surface is built.
In short
- State whether the case is conformative or reorganized — the default assumption is conformative
- Aim for contact comparable to adjacent teeth, directed axially
- Non-working interferences are the most damaging and the most often missed
- Mounted casts earn their place beyond single units; a facebow matters where guidance is built
- An unstable intercuspal position needs establishing before it can be restored to
More on clinical
Discuss a case
Where a case sits between options, a short conversation before preparation is usually quicker than resolving it afterwards.