Accurate Bite Registration — How the Lab Avoids Errors

Bite registration is the first point of communication between you and the lab. If it's incorrect, everything beyond it is incorrect.

Incorrect registration = incorrect mandibular position in the articulator = incorrect occlusion at delivery = patient in the chair: "something doesn't feel right," 30 minutes of grinding.

This is not a lab error. This is a registration error. And it can be entirely avoided.

Does Registration Really Matter?

Yes. Registration is the direct transmission of the patient's tooth position to the lab's articulator. If the registration indicates an incorrect position, the entire prosthetic design is built on a faulty foundation.

Example: Full reconstruction of 8 units. You take the registration with a thick layer of material. The patient bites too hard — the mandible is pushed forward by 1-2 mm. The lab mounts the models — they believe this position is the patient's actual bite. They design the occlusal curves for an FWD position, not for centric relation.

The restoration goes to the practice. At a normal bite, the patient has an occlusion that is too low in the anterior. You grind the entire curve of Spee — 45 minutes of work.

Good registration: thin layer, accurate position, clear image for the lab. The restoration arrives perfectly.

Registration Materials — PVS Silicone Only

Material	Accuracy	Dimensional Stability	Comment	Recommendation
PVS Silicone (GC Futar, Regisil, Coltene President)	Very High	Stable for 24h+	Industry standard. Sets controllably, dimensions stable.	YES
Composite	Low (2–5%)	Varies +/- 1–2% with temperature	Polymerization shrinkage + thermal expansion/contraction = inaccuracy.	NO
Wax	Low	Variable — softens in the mouth	Distortion during mastication, material loss = position error.	NO
Modeling Clay	Low	Highly variable with temperature	Distortion, loss, mess — never use.	NO

Rule: Only polyvinyl siloxane (PVS) silicone. This is the only family of materials that meets the precision required for occlusal registration.

Registration Errors — Where the Lab Goes Wrong

Error #1: Excessively Thick Material Layer

The patient bites on a thick layer (3–5 mm). The mandible is displaced superiorly — altering the actual bite position. Result: a "false" maximum intercuspation — too high, not actual.

Correctly: A thin layer (1–2 mm). You register tooth contact, not an air cushion between models.

Error #2: Insufficient Material — Gaps in Registration

Some teeth are not captured in the registration — there is insufficient material. The lab cannot see where the lateral contacts are or where there are gaps. They work with incomplete data.

Correctly: All occlusal surfaces covered with material. Every contact area visible and documented.

Error #3: Registration Outside of Maximum Intercuspation

The patient bites into the registration in an anterior, shifted position, or in centric relation (if you don't want it). The lab thinks this is the actual bite.

Correctly: For most cases — maximum intercuspation (MI, the point where teeth make the best contact). This is a natural and most stable position for the patient.

Error #4: Contaminated Registration

Saliva, food debris, blood between the material and the teeth. Distortions in the registration. The lab sees noise instead of a clear image.

Correctly: Dry field — cotton rolls or cofferdam. No contaminants between the material and the teeth.

Error #5: Registration Deformation During Transport

The registration is received pliable — soft and prone to deformation. You send it unprotected. The lab receives a crushed registration — the position is altered.

Correctly: Registration in a rigid container, protected from compression. Hard case or box — no pressure.

6-Step Procedure — Correct Registration

1. Preparation of the operating field — patient seated, comfortable position, dry field.
2. Material application — a thin layer (1–2 mm) of PVS silicone on all occlusal surfaces.
3. Patient instructions — close your mouth, place lower teeth on upper, do not chew, do not move, sit still.
4. Waiting for polymerization — PVS silicone sets in 30–60 seconds, do not remove earlier.
5. Intraoral verification — check that all occlusal surfaces are covered, no distortions.
6. Removal and protection — one motion, no twisting, wash with water, place in a rigid box.

Maximum Intercuspation vs. Centric Relation

Concept	When	How to Register
Maximum Intercuspation	Default — 95% of cases	Patient closes naturally, teeth make the best contact.
Centric Relation	TMJ disorders, planned occlusal change	Requires a special procedure — eliminating muscular habits.

In practice: If the clinician does not specify centric relation, we always register maximum intercuspation.

Can I register outside of maximum intercuspation?

No, if the clinician doesn't specifically request it. The standard is maximum intercuspation — the patient's natural tooth position. Centric relation is used only in special cases.

How long should the patient hold the registration in their mouth?

As long as the silicone sets — 30–60 seconds. Too long = risk of fatigue, movement, position change.

Can I send the registration without models?

No. Registration is a position in a vacuum — without upper and lower models, the lab has no context.

What if the patient has a strong gag reflex?

Work quickly, methodically. Stabilize the patient's head, give clear instructions. Consider preoperative relaxation.

Can I use composite for registration?

No. Composite shrinks during polymerization (5–7%) and changes dimensions with temperature fluctuations. PVS silicone is the only suitable family of materials.