Articulators and facebow: when the record genuinely matters and when it is ritual

The facebow is one of the instruments where the gap between what is taught and what is practised is widest. Many practices own one and never use it; others use it always, even when it changes nothing.

It is worth clarifying what it actually records: the position of the maxilla relative to the terminal hinge axis and a cranial reference plane. It does not record occlusion, does not record mandibular movement, and does not replace the interocclusal record.

Its usefulness depends on how far the case departs from average values. On a single unit, in a patient with stable occlusion and preserved contacts, average-value mounting produces an equivalent result.

On an extensive rehabilitation, where the occlusal plane must be rebuilt from nothing and no residual reference exists, the true maxillary position changes the outcome. That is where the facebow stops being ritual.

Articulators fall into three categories and the choice follows the same logic. Average-value instruments have fixed condylar paths based on statistical values, and cover most conservative prosthodontics.

Semi-adjustable instruments allow condylar inclination and Bennett angle to be set from individual intraoral records. They are the most widespread compromise and sufficient in nearly all complex cases.

Fully adjustable instruments reproduce condylar paths recorded by pantography. Time and cost justify them only in full-mouth rehabilitations with joint problems.

Recording centric relation matters more than the articulator itself. Mounting on a sophisticated instrument with a faulty record faithfully reproduces a wrong position, and that is worse than an average value with a correct record.

Bimanual manipulation has the most robust documentation, but requires a relaxed patient with uncontracted musculature. In a patient with muscle pain the record obtained is not reproducible, and it is better to precede it with relaxation therapy.

The recording material must be rigid after setting and not deform during mounting. Waxes are convenient but yield; high-hardness bite registration silicones are more reliable, provided the thickness stays minimal.

Excessive thickness introduces a rotational error: a mandible recorded in an open position is then closed on the articulator along a different arc from the physiological one, and contacts end up displaced.

Diagnostic waxing is the real reason mounting casts is worthwhile. It allows spaces, guidance and occlusal plane to be verified before preparing, and becomes the matrix for provisionals: what was designed on the cast is transferred to the mouth.

In summary, facebow and individualised articulator are justified when no residual occlusal reference exists. Outside that case, the time invested yields more in the centric record and the diagnostic wax-up.