# Recording Jaw Relations > Recording jaw relations for BDS Prosthodontics — vertical dimension, freeway space, centric relation, record blocks and gothic arch tracing. - Canonical URL: https://prepelephant.com/topics/bds/prosthodontics/jaw-relations-recording - Exam / course: BDS · Subject: Prosthodontics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Recording Jaw Relations", PrepElephant, https://prepelephant.com/topics/bds/prosthodontics/jaw-relations-recording ## Direct answer Recording jaw relations transfers the patient's vertical and horizontal mandibular position from the mouth to the articulator using record blocks (an acrylic or shellac base with a wax occlusal rim). The vertical component fixes the occlusal vertical dimension at 2 to 4 mm below the rest position (the freeway space), while the horizontal component records centric relation — the most retruded physiological position of the condyles — by static check records, functional methods or gothic arch tracing. An error here cannot be corrected later in the denture. ## What you must remember - Vertical dimension at rest is determined by muscle tonus; the interocclusal rest space (freeway space) averages 2 to 4 mm and is subtracted from rest position to obtain occlusal vertical dimension. - Methods of recording vertical dimension: facial measurement and equal facial thirds (Willis bite gauge), phonetics, swallowing, facial expression and the patient's tactile sense — always combine at least two. - Silverman's closest speaking space during "S" sounds, asking the patient to count "sixty-six" or say "Mississippi", is about 1 to 2 mm and cross-checks the vertical dimension. - "M" sounds with the lips gently touching help find the rest position of the mandible before any measurement is taken. - Centric relation is the most retruded physiological relation of the mandible to the maxillae at the terminal hinge position — reproducible, whereas maximum intercuspation is not. - Recording methods: static interocclusal check records in wax or paste, functional chew-in records, and graphic tracing — intraoral (Gysi) or extraoral (Stansbury-type) gothic arch, whose apex marks centric relation. - Occlusal rims are shaped first: the maxillary rim trimmed to lie 1 to 2 mm below the upper lip at rest, its plane parallel to the interpupillary line in front and to Camper's line (ala to tragus) behind. - A protrusive check record is also made to set the articulator's horizontal condylar guidance; Hanau's formula L = H/8 + 12 derives the lateral inclination from the horizontal one — a classic viva one-liner. ## A typical sequence at the chair After the record bases are verified for adaptation and stability, contour the maxillary rim until the lips are supported naturally, showing 1 to 2 mm below the upper lip at rest; scribe the midline and canine lines on its face. Set the mandibular rim height so that, at first contact, the freeway space measures 3 mm — check by marking dots on nose and chin, having the patient swallow and relax, and measuring the rest distance with a Willis gauge. Confirm with phonetics: counting "sixty-six" should give a clear "S" with 1 to 2 mm of clearance; whistling or lisping signals over-closure or excess height. For the horizontal record, soften a film of wax only on the mandibular rim, guide the patient's chin so the mandible closes on its terminal hinge arc — a gentle backward pressure at the chin with support at the forehead, never forcing — and let the rims indent. Alternatively place a central bearing screw and plate, obtain a Gothic arch tracing, and lock the intraoral tracer at the apex before letting the patient close through a registering medium. Verify any record twice: remove, reseat and confirm the same indentations, because an unverified centric record is the single commonest denture error. ## Strain and slip Forcing the mandible backwards until the chin trembles records a strained, non-physiological position that the patient cannot maintain in function — examiners describe exactly this sign and ask what it means. The second error is testing the vertical dimension only by measurements and skipping the phonetic cross-check; a patient with a long upper lip can hide a 3 mm error from the facial-thirds method. Finally, candidates forget that record bases must be stable first: a rocking base records a false vertical dimension regardless of technique, so the examiner's leading question "what do you check before recording jaw relations?" expects the answer "adaptation and stability of the record base". ## Frequently asked questions ### What is the freeway space and how much is it? The interocclusal gap between vertical dimension at rest and at occlusion, averaging 2 to 4 mm; it must be built into complete dentures or the patient feels strained and the muscles tire. ### Why is centric relation recorded rather than maximum intercuspation? In an edentulous patient there is no intercuspation; centric relation is the reproducible terminal hinge position, allowing repeated closure and error-free transfer to the articulator. ### What does the apex of a gothic arch tracing represent? The most retruded position of the condyles — centric relation — where the tracing needle's forward point meets the two lateral excursive arms. ### How are the occlusal rim and its plane oriented? Roughly 1 to 2 mm below the upper lip at rest in front, parallel to the interpupillary line anteriorly and to Camper's line (ala to tragus) posteriorly. ### What is Hanau's formula used for? L = H/8 + 12 estimates the lateral condylar inclination from the recorded horizontal condylar inclination when setting certain semi-adjustable articulators — a favourite short note.