Occlusal Records in Dentistry
Articulators · Facebow · Centric Relation · CR Recording Techniques · Occlusal Analysis
TL;DR
Occlusal records are the clinical and laboratory procedures used to capture and reproduce the three-dimensional spatial relationship between the maxillary and mandibular arches — and to programme articulators (mechanical jaw simulators) so that indirect restorations can be fabricated outside the mouth in an accurate simulation of the patient’s own jaw movements. The hierarchy of records is: facebow (relates maxillary cast to the hinge axis of the articulator) → centric relation record (positions mandibular cast relative to maxillary cast at the reproducible reference jaw position) → protrusive record (programmes condylar guidance angle) → lateral record (programmes Bennett angle). These records, taken together with mounted study casts, provide the information needed to fabricate restorations with correct occlusal contacts and jaw movement compatibility.
- Articulators are classified into four classes by their ability to reproduce jaw movements: Class I (hinge-only/simple) — can open and close in a hinge motion only; no lateral or protrusive movement possible; used only for study models and immediate restorations where precision is not required, or for complete dentures where average value articulators suffice for bilateral balanced occlusion development; no facebow required. Class II (average-value) — simulates average condylar guidance values without patient-specific adjustment; fixed condylar inclination (~30°) and fixed Bennett angle (~15°); more useful than Class I for simple restorations; still no patient-specific programming; suitable for single-unit restorations where occlusal demands are moderate. Class III (semi-adjustable) — the clinical standard; condylar guidance angle set from protrusive record; Bennett angle set from lateral record (or adjusted empirically); requires facebow for maxillary cast mounting; used for: FPD, implant crowns, full-mouth rehabilitation (up to 6 units), study casts for treatment planning. Class IV (fully adjustable) — all condylar guidance parameters individually set from pantographic or axiographic jaw movement records; used for complex full-mouth rehabilitations, gnathological treatment, or research; high cost and complexity limit routine clinical use.
- Centric relation (CR) is the reference jaw position for all complex restorations: The GPT-9 (2017) definition of CR is the most superior, anterior, musculoskeletally stable position of the condylar-disk assembly against the articular eminences — i.e., a position determined by the temporomandibular joint ligaments and musculature, not by tooth contact. This is the only reproducible reference position of the mandible. Maximum intercuspation (MIP/ICP), by contrast, is determined by the occlusal surfaces of the teeth — it is tooth-guided, not joint-guided, and changes whenever the teeth are altered (by caries, wear, or restorations). The CR–CO slide (the arc of movement from CR first contact to MIP) averages 1–2mm and is clinically insignificant in most patients. However, when fabricating restorations that will involve multiple teeth simultaneously (full-mouth rehabilitation, complete dentures, patients with parafunctional habits or symptoms), planning in CR is essential to ensure the restoration is stable against the musculoskeletal reference position rather than the current (potentially compromised) MIP.
- Bimanual manipulation (Dawson technique) is the most reliable CR recording technique: The patient is supine; the operator stands at the head of the chair; both thumbs are on the symphysis; fingers wrap below the inferior border of the mandible; the clinician guides the mandible superiorly and anteriorly along the arc of the terminal hinge axis until the condyles are seated in the highest, most anterior position. This must be performed with the muscles relaxed (patient should not clench or “help” — “let your jaw be like a loose door hinge”). An anterior deprogrammer (Lucia jig — custom acrylic button on the upper central incisors; only tooth contact is on the incisors, preventing posterior muscle splinting) is often applied first for 20–30 minutes to eliminate the engram (learned muscle memory of habitual MIP closure). The CR first contact is then identified and the slide to MIP documented. The technique is validated by reproducibility — three sequential attempts to seat the condyles should produce the same CO.
- Bite registration materials have a clear hierarchy of accuracy: PVS bite registration material (polyvinyl siloxane formulated to low viscosity and rapid set) is the most accurate and dimensionally stable — it does not distort after removal, can be poured immediately or stored, and is the gold standard for complex restorations. ZOE bite registration paste (zinc oxide eugenol, paired two-component paste) sets hard and rigid, is dimensionally stable but brittle, and is suitable for edentulous patients (complete dentures) where the material must bridge the interarch space without tooth contacts guiding the record. Wax bite registration (horseshoe wax wafer, warmed and occluded) is the least accurate — wax creeps (deforms plastically under pressure) and distorts when removed from the mouth; it is appropriate only for simple situations or when other materials are unavailable; should never be used for complex restorations or mounted study casts.
- Occlusal interferences must be characterised before complex treatment: Working side interferences occur during lateral excursion on the side the mandible moves toward — posterior tooth contacts that displace the condyle inferiorly on the working side; they are more damaging to the TMJ than non-working side interferences because they produce direct loading on the working-side condyle in an inferior direction (away from the fossa). Non-working side (balancing side) interferences occur on the side opposite to the direction of lateral movement — these are the most damaging posterior contacts in natural dentition because they produce a class III lever arm effect: the non-working contact acts as the fulcrum, levering the working condyle inferiorly out of the fossa and creating compressive load on the non-working condyle against the articular eminence. They should be eliminated in all fixed prosthodontic occlusal schemes (canine-guided or group function). Exception: complete dentures require bilateral balanced occlusion — deliberate non-working contacts to prevent denture tipping.
Key Facts
What Are Occlusal Records?
Occlusal records are clinical records of the three-dimensional spatial relationships between the maxillary and mandibular dental arches — and between those arches and the temporomandibular joint — that are used to mount dental casts on articulators for diagnostic analysis and restoration fabrication. The term encompasses: jaw relation records (centric relation records, centric occlusion records, protrusive records, lateral records), facebow records, and the process of transferring those records to an articulator. When a dental technician fabricates a crown, bridge, or complete denture in the laboratory, the restoration is fabricated on casts (plaster models) of the patient’s teeth that are mounted on an articulator. The accuracy of that restoration’s occlusal contacts depends entirely on whether the articulator accurately replicates the patient’s own jaw relationships. Occlusal records make this possible.
Poorly taken occlusal records are one of the most common causes of occlusal errors in indirect restorations — restorations that are “high” on delivery, restorations that create deflective contacts, and restorations that cause muscle soreness or TMD symptoms. Understanding the theory and technique of occlusal records is therefore essential for clinical practice, and these concepts are heavily tested on board examinations.
Why It Matters
Occlusal records are consistently tested on the INBDE, NBDE, and clinical licensing examinations. High-yield topics include: the GPT-9 definition of centric relation (and the clarification that “most retruded” is outdated); the purpose of the facebow; the difference between arbitrary and kinematic hinge axis; the Dawson bimanual manipulation technique; what the protrusive record sets (condylar guidance angle) vs. what the lateral record sets (Bennett angle); the accuracy hierarchy of bite registration materials; Angle’s classification of malocclusion; and the distinction between working side and non-working side interferences. The clinical application also connects directly to complete dentures (balanced occlusion), fixed prosthodontics (occlusal scheme selection), and TMD management (CR vs. MIP slide).
Articulators
An articulator is a mechanical device that receives the dental casts mounted to represent the maxillary and mandibular arches, and replicates the jaw movements of the patient so that dental restorations can be fabricated with accurate occlusal relationships. The degree to which an articulator can replicate patient-specific jaw movements determines its clinical utility and the complexity of cases for which it is appropriate.
Articulator Classification — Classes I–IV
| Class | Type | Movements Simulated | Facebow Required | Patient-Specific Programming | Clinical Use | Examples |
|---|---|---|---|---|---|---|
| Class I | Simple hinge | Vertical opening/closing only — hinge motion; no lateral or protrusive excursion simulation | No | None | Study model mounting for initial assessment; immediate restorations where a brief adjustment is expected; some complete denture techniques (using pre-set average values) | Simple hinge articulators (generic) |
| Class II | Average-value | Vertical + some lateral and protrusive movement with fixed average condylar guidance values (typically 30° condylar inclination; 15° Bennett angle) | No | None (pre-set averages — same for all patients) | Simple single-unit restorations; Class I/II inlays with no complex occlusal geometry; short-span FPDs in patients with normal TMJ function; occlusal adjustment where precise lateral guidance replication is not required | Hanau 130–21 (older), generic average-value articulators |
| Class III | Semi-adjustable | Vertical, protrusive, and lateral; condylar guidance angle set from patient’s protrusive record; Bennett angle set from lateral record or fixed Bennett angle formula | Yes — required for accurate maxillary cast mounting | Condylar guidance (protrusive record) + Bennett angle (lateral record) | FPD (3+ units); implant-supported restorations; full-mouth occlusal rehabilitation (≤6 units); complete dentures; study cast analysis for treatment planning; the clinical standard for complex prosthodontic work | Whip-Mix 8500/2240; Hanau Wide-Vue; Denar Mark II/III |
| Class IV | Fully adjustable | All condylar path movements — condylar inclination, Bennett angle, condylar path curvature — set individually from pantographic or axiographic tracings | Yes — with kinematic facebow (locates the true hinge axis) | All parameters from patient-specific jaw movement recordings (pantograph or axiograph) | Very complex full-mouth rehabilitations; gnathological treatment in TMD; maxillofacial cases; research; rarely used in routine practice due to cost and complexity of setup | Panadent PCH; Denar D5A; Stuart; Gnathoscope |
Semi-Adjustable Articulators — Clinical Protocol
The semi-adjustable articulator (Class III) is the standard for complex clinical cases. The protocol for mounting casts on a semi-adjustable articulator is: (1) Facebow transfer — the facebow record locates the maxillary arch relative to the transverse hinge axis; the maxillary cast is mounted to the upper bow of the articulator using this record; (2) CR mounting of the mandibular cast — the CR record (or alternatively the MIP/ICP record for straightforward single-unit cases) is used to mount the mandibular cast relative to the maxillary cast; (3) Protrusive record — the patient protrudes the mandible approximately 5–6mm forward and bites into a registration material; this record is used to set the condylar guidance angle (slope of the condylar path) on the articulator; (4) Bennett angle (lateral record) — the patient makes a lateral excursion and bites into registration material; this sets the Bennett angle (the angle formed by the sagittal plane and the path of the non-working condyle during lateral movement).
Facebow Transfer
Purpose and Anatomical Basis
The facebow is a rigid caliper-like instrument used to record the three-dimensional spatial relationship between the maxillary dental arch (or edentulous ridge) and the transverse hinge axis of the mandible. Without a facebow, the maxillary cast is positioned on the articulator in an arbitrary location — the distance from the hinge axis of the articulator to the occlusal surfaces of the maxillary cast does not match the distance from the patient’s condylar hinge axis to the patient’s maxillary occlusal surfaces. The consequence: when the articulator is opened, the maxillary cast moves in an arc that does not match the patient’s actual jaw opening arc. The further from the hinge axis the teeth are, the greater the arc discrepancy. For most clinical cases, this arc discrepancy is small but can result in occlusal contacts that differ from what will occur intraorally — a significant problem when fabricating multi-unit fixed restorations or complete dentures.
The facebow also records the orientation of the maxillary arch relative to a reference plane (usually the Frankfort horizontal plane — from the porion, the top of the external auditory meatus, to the orbitale, the lowest point of the orbital rim). This orientation determines whether the occlusal plane on the articulator is correctly angled relative to the condylar elements of the articulator, which affects the incisal guidance angle and compensating curve relationships during fabrication.
Arbitrary vs. Kinematic Hinge Axis Location
The transverse hinge axis is the imaginary axis about which the mandible rotates in a purely hinge motion (terminal hinge closure) — it passes through both condylar heads. The true (kinematic) hinge axis location varies between individuals and must be accurately located for a fully adjustable articulator. Two approaches exist:
- Arbitrary hinge axis: The hinge axis is estimated to lie at a standardised anatomical landmark — most commonly 13mm anterior to the tragus of the ear on the tragus–corner of mouth line (Beyron point). An arbitrary facebow uses this estimated point. Studies show the arbitrary point is within 5mm of the true kinematic hinge axis in ~90% of patients — close enough for semi-adjustable articulator use. Arbitrary facebows are used for the vast majority of clinical cases including complex full-mouth rehabilitation with semi-adjustable articulators.
- Kinematic (true) hinge axis: The true hinge axis is located using a kinematic facebow — the patient opens and closes repeatedly while the operator progressively adjusts locating arms until a point on the skin over the condylar region shows no movement during hinge opening (the axis of rotation). This precise location is required only when using a fully adjustable (Class IV) articulator, where the accuracy of condylar path programming depends on precise hinge axis location.
Centric Relation
Definition and Clinical Significance
Centric relation (CR) is defined by the Glossary of Prosthodontic Terms, 9th edition (GPT-9, 2017) as “the maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anterior-superior position against the slopes of the articular eminences. This position is independent of tooth contact. This position is clinically discernible when the mandible is directed superiorly and anteriorly. It is restricted to a purely rotary movement about the transverse hinge axis.”
Three critical points from this definition: (1) condyle in the most superior, anterior position — not retruded (older, now-incorrect definition said “most retruded” position); (2) independent of tooth contact — CR is a joint-determined position, not a tooth-determined position; (3) the terminal hinge axis — pure rotation about a fixed axis (the only position from which a reproducible hinge arc can be generated). CR is reproducible in any given patient (with proper technique), making it the only reliable reference position for recording and reproducing jaw relationships.
CR Recording Techniques
| Technique | Description | Advantages | Limitations / Notes |
|---|---|---|---|
| Bimanual manipulation (Dawson technique) | Supine patient; operator at head; thumbs on symphysis, fingers below mandible; guide mandible superiorly and anteriorly along terminal hinge arc; patient must be relaxed (not clenching) | Most widely validated technique; reproducible; directly loads TMJ to seat condyle; clinically studied extensively | Requires relaxed patient; muscle engram (habitual closure) must be deprogrammed first; learning curve for operator; not appropriate if patient has active TMJ pain/arthritis |
| Anterior deprogrammer (Lucia jig / CR leaf gauge) | Custom acrylic anterior stop (Lucia jig) or series of thin plastic leaves (CR leaf gauge) placed between the maxillary and mandibular anterior teeth; patient closes only on the anterior stop; no posterior tooth contact for 20–30 minutes → eliminates habitual muscle memory (engram) of MIP closure; CR recording taken after deprogramming | Reliably eliminates habitual muscle engram; relatively technique-insensitive; patient actively participates; well-accepted | Takes time (20–30 min deprogramming); custom jig fabrication required; not suitable for patients with anterior open bite; leaf gauge requires operator to progressively remove leaves to identify minimum thickness for CR closure |
| Chin-point guidance (unilateral chin guidance) | Operator places thumb and index finger on the chin and guides the mandible hinge-up into CR; less bilateral control than bimanual manipulation | Simple; can be done without specific positioning of the patient | Less precise than bimanual manipulation; tends to produce slight posterior positioning of condyle rather than true superior-anterior position; less reproducible; now less favoured |
| Central bearing point device | Custom trays with a central bearing point (a single central contact point between maxillary and mandibular trays, located at the midpalatal region); patient taps/swallows to seat mandible; the device eliminates eccentric forces from posterior teeth and muscle; used for edentulous patients in complete denture construction | Excellent for edentulous patients; eliminates muscle influence; generates repeatable CR contact point | Complex setup; requires custom trays; primarily for complete denture use |
| Power centric / swallow technique | Patient asked to swallow or press tongue to the roof of the mouth — natural reflexive posturing of the mandible tends to seat the condyles superiorly; used as a quick verification or preliminary guide | No special equipment; useful as a check technique | Not reliable enough as a primary recording technique; muscle tension during swallowing may deviate the mandible; appropriate only as a supplementary check |
Bite Registration Materials
| Material | Type | Accuracy | Setting | Clinical Use | Key Property |
|---|---|---|---|---|---|
| PVS bite registration | Addition-cured polyvinyl siloxane — light-body/medium-body viscosity formulated specifically for bite registration (very low viscosity, rapid set ~30 sec) | Highest accuracy; gold standard | Auto-mix gun; sets in ~30–60 seconds; dimensionally stable long-term; no by-products | All complex restorations: FPD, full-mouth rehabilitation, implant prosthetics, single crowns where precise articulation needed | No distortion on removal; can be poured immediately or stored; resists creep; platinum-catalysed addition reaction same as impression PVS — no gaseous by-products → stable |
| ZOE bite registration paste | Zinc oxide eugenol paste (two-component — zinc oxide paste + eugenol paste) | High accuracy when set; brittle | Sets hard and rigid; ~3–5 minutes (temperature/humidity dependent) | Edentulous patients (complete dentures, immediate dentures); situations where material must bridge large interarch gap without tooth guidance | Sets very hard (rigid); does not distort after setting; but brittle and fractures on removal if not careful; eugenol may inhibit polymerisation of resin materials (same issue as temporary cements) |
| Polyether bite registration | Ring-opening ionic polyether — same chemistry as polyether impression material but lower viscosity | High accuracy; dimensionally stable | Auto-mix; ~30–60 seconds; rigid set | FPD, single crowns; similar indications to PVS bite registration | Very stiff after setting (similar to polyether impressions); can be difficult to seat casts into registration if interarch space is tight; absorbs water (pour promptly) |
| Wax (bite wafer) | Wax horseshoe wafer — warmed in warm water or flame, placed between arches, patient closes into MIP/CR | Lowest accuracy; not recommended for complex cases | No setting reaction — cools and hardens; significant creep under pressure | Acceptable for simple single-unit restorations where the restoration will be adjusted intraorally; quick chairside check; NOT for mounted study casts or complex cases | Creep (plastic deformation) at body and room temperature → dimensional changes over time; distorts on removal; wax wafer thickness separates the casts slightly → artificially opens vertical dimension → occlusal contacts on restoration will be open when tried in |
| Plaster (interocclusal plaster) | Dental plaster (calcium sulphate hemihydrate) mixed to thin consistency; sets rigid | High accuracy when technique is correct | Fast-setting (~1–2 minutes); sets rigid; brittle | Used in some edentulous complete denture techniques; research settings; historically used before PVS bite materials were available | Dimensionally accurate but very brittle; fractures easily during removal and handling; casts must be seated immediately before plaster sets; technique-sensitive; largely replaced by PVS bite registration in contemporary practice |
Protrusive and Lateral Records — Programming the Articulator
Protrusive Record and Condylar Guidance Angle
The protrusive record is a bite registration taken with the mandible protruded approximately 5–6mm forward from CR (but not to the edge-to-edge position). The patient bites into PVS bite registration material or wax in this protrusive position, and the hardened registration is placed on the articulator. The articulator’s condylar guidance angle (the slope of the condylar path relative to the Frankfort horizontal plane) is then adjusted until the articulator replicates the protrusive position recorded in the material. This angle — the condylar guidance angle (or Hanau’s condylar inclination) — typically ranges from 0° to 60° with an average of ~30°. The steeper the condylar path (higher angle), the steeper the posterior disclusion during protrusion (occlusion theory: steeper condylar guidance → stronger disclusion of posterior teeth in protrusion). In Hanau’s Quint (for complete dentures): condylar guidance is a fixed determinant (set by the patient’s anatomy); cusp angle is an adjustable determinant that must be increased or decreased to maintain bilateral balanced occlusion when condylar guidance changes.
Bennett Angle and Lateral Records
The Bennett angle is the angle between the sagittal plane and the path of the non-working (orbiting) condyle during lateral jaw movement. When the mandible moves laterally (e.g., to the right working side), the left (non-working) condyle moves anteriorly, medially, and inferiorly down the articular eminence — this is the non-working condylar path. The Bennett angle is the horizontal component of this path. Average Bennett angle: 7.5° (range 0–30°). The lateral record is a bite registration taken with the mandible in approximately 3–5mm of lateral excursion; this is placed on the mounted casts on the articulator, and the Bennett angle setting is adjusted to match the lateral position. Some articulators have immediate sideshift (Bennett movement/shift) capability — the medially-directed immediate lateral shift of the non-working condyle at the beginning of lateral excursion before the condyle begins its downward-forward arc. This is programmed separately on fully adjustable articulators.
Occlusal Analysis and Interferences
Angle’s Classification of Malocclusion
Edward Angle (1899) classified malocclusion based on the relationship of the maxillary first permanent molar to the mandibular first permanent molar (the key of occlusion). This classification remains the standard terminology for describing anteroposterior jaw relationships:
| Class | Molar Relationship | Clinical Description |
|---|---|---|
| Class I | Mesiobuccal cusp of the maxillary first permanent molar occludes with the buccal groove of the mandibular first permanent molar | Normal anteroposterior jaw relationship; the ideal. Malocclusion (crowding, spacing, rotation) may be present in Class I due to tooth-size or arch-size discrepancy, but the skeletal relationship is normal |
| Class II | Mesiobuccal cusp of maxillary first molar occludes anterior to the buccal groove of mandibular first molar (mandible is distal to normal) | Retruded mandible or protruded maxilla (retrognathic mandible or prognathic maxilla). Class II, Div. 1: proclined maxillary incisors + increased overjet. Class II, Div. 2: retroclined maxillary central incisors with proclined lateral incisors + deep overbite (OB). Most common malocclusion in Caucasian populations |
| Class III | Mesiobuccal cusp of maxillary first molar occludes posterior to the buccal groove of mandibular first molar (mandible is mesial to normal) | Prognathic mandible or retrognathic maxilla. May have anterior crossbite or edge-to-edge incisor relationship. True Class III (skeletal) vs. pseudo-Class III (functional mandibular protrusion). Less common in Caucasian populations; more common in East Asian populations |
Angle’s classification does not address: vertical relationships (overbite, open bite); transverse relationships (crossbite); tooth irregularities; or skeletal vs. dental origin of the malocclusion. It is a description, not a diagnosis.
Occlusal Interferences — Working, Non-Working, Protrusive
| Interference Type | Definition | Jaw Position | Clinical Significance | Management |
|---|---|---|---|---|
| Working side (WS) interference | Posterior tooth contact on the ipsilateral (working) side during lateral excursion that prevents or disrupts canine-guided or group function contact pattern on the working side | Lateral excursion; mandible has moved to the working side | Causes lateral loading of the working-side TMJ in an inferior direction (condyle is pulled away from fossa); can cause muscle pain, headache, and accelerate tooth wear; less damaging than NWS interferences to the TMJ | Occlusal adjustment (selective grinding); design of new restorations to avoid WS interferences; appropriate occlusal scheme selection (canine-guided: all posterior teeth disclude on working side; group function: only selected posterior teeth in contact) |
| Non-working (NWS) / balancing side interference | Posterior tooth contact on the contralateral (non-working) side during lateral excursion | Lateral excursion; mandible has moved away from the NWS | Most damaging type: creates a Class III lever with the NWS contact as the fulcrum → working-side condyle is levered inferiorly out of the fossa → compressive loading on NWS condyle against articular eminence. Can cause TMD pain, disc displacement, tooth fracture, and restoration failure. Must be eliminated in all fixed prosthodontic schemes | Eliminate by occlusal adjustment; ensure new restorations do not create NWS contacts; NWS contacts (balancing contacts) are ONLY acceptable (and desirable) in complete dentures to prevent denture tipping |
| Protrusive interference | Posterior tooth contact during mandibular protrusion that prevents anterior disclusion (anterior teeth guiding the protrusion) | Protrusion from ICP/CR toward edge-to-edge incisal contact | Posterior teeth are not designed for protrusive loading; protrusive interferences create non-axial loads on posterior teeth; can cause tooth mobility, pain, and restoration fracture; normal: anterior teeth guide protrusion with posterior disclusion | Occlusal adjustment or restorative adjustment of posterior cusps; increase anterior vertical overlap (OB) to steepen incisal guidance; provide adequate compensating curve to maintain posterior clearance in protrusion |
| CR–CO deflective contact (CO slide contact) | The first tooth contact when the mandible closes from CR to MIP; the mandible must then slide from this contact to reach MIP | At the terminal hinge axis position (CR) on first closure | A deflective contact is not an interference per se, but it causes the mandible to be deflected from its natural joint-guided closure path. Large deflective contacts (>2mm, or lateral component) associated with muscle hyperactivity and TMD in susceptible patients | For small deflective contacts in asymptomatic patients: no treatment indicated. For large deflective contacts (>2mm or lateral), symptomatic patients, or those requiring full-mouth restoration: plan treatment in CR; adjust or restore to eliminate the deflective contact |
Mounted Study Casts and Treatment Planning
Diagnostic casts mounted on a semi-adjustable articulator provide information that cannot be obtained from intraoral examination alone. They allow: (a) assessment of occlusal contacts in CR — identifying the CR first contact and the CR–CO slide without the confounding effects of muscle activity and patient cooperation during intraoral examination; (b) vertical dimension assessment — evaluating freeway space and OVD in three dimensions; (c) cross-arch assessment — assessing how changes to teeth on one arch affect the entire occlusal scheme; (d) diagnostic wax-up — the laboratory can add wax to the casts to simulate proposed restorations before any teeth are prepared, allowing assessment of the proposed occlusal scheme, aesthetics, and space requirements; (e) occlusal interference visualisation in all excursions — articulator movements reveal protrusive and lateral interferences that might not be detectable intraorally with articulating paper alone. Mounted study casts are mandatory for: full-mouth rehabilitation; implant treatment planning; complete denture fabrication; and any case where the OVD is to be altered.
Clinical Considerations
- The protrusive record must be taken after the CR record for mounting: The sequence is critical. First: facebow record → mount maxillary cast. Second: CR record → mount mandibular cast. Third (only after both casts are mounted): protrusive record → set condylar guidance angle. Fourth: lateral record → set Bennett angle. If the protrusive record is taken before the mandibular cast is mounted in CR, there is no reference point for the protrusive position because the mandibular cast has no defined starting position on the articulator yet. The mounted CR position is the starting reference from which the protrusive excursion is measured.
- Canine-guided occlusion is the preferred occlusal scheme for natural dentition and fixed prosthodontics: In canine-guided (mutually protected) occlusion: during lateral excursion, the canine contacts on the working side guide the movement, and all posterior teeth disclude immediately. This protects posterior teeth (and their restorations) from harmful lateral forces — posterior teeth have limited capacity for lateral loading (conical roots, short crown-to-root ratios in some cases). The canine, by contrast, has favourable characteristics for guidance: long root with large PDL surface area; location at the corner of the arch; the steep buccal cusp slope of the canine produces rapid posterior disclusion. The canine also provides proprioceptive feedback during lateral movements. In group function occlusion (used when the canine cannot provide guidance — short canine, steep condylar guidance, flat incisal guidance), the load is shared among working-side posterior teeth. Group function is appropriate but requires accurate occlusal adjustment to ensure smooth, even contact on all working-side teeth.
- The CR recording technique must be verified for reproducibility: A single CR record should never be accepted without verification. The clinical test for reproducibility: perform bimanual manipulation three times in rapid succession. The three CR closures should contact the same tooth or teeth in the same location — if the contact point varies between attempts, the patient’s mandible is not consistently reaching CR (muscle tension, TMD, or inadequate technique). This is called the “three-point test” or reproducibility check. Only proceed to record taking once three reproducible contacts confirm CR seating.
- OVD changes in complete dentures — the OVD should ideally be maintained, not arbitrarily increased: When mounting complete denture casts on an articulator, the OVD (occlusal vertical dimension) is set by the wax occlusal rims (or a mechanical bite gauge). The OVD determines the position of the mandible at maximum intercuspation — if it is set too high, the patient will have insufficient freeway space and will have persistent muscle activity and soreness; if set too low, the patient will have altered aesthetics, a collapsed lower face, and may experience TMJ discomfort. The OVD of existing complete dentures should be evaluated first: if the patient is comfortable with their existing dentures, replicate the OVD. If the existing OVD is clearly incorrect (lack of FWS, collapsed face height), assess using phonetics (/s/ sound, /f/ and /v/ sounds) and the rest position minus FWS method before altering it.
- Mounted casts should be checked before fabrication begins in the laboratory: After mounting, the clinician should verify: (a) that the dental midlines are correct on the casts (not shifted from impression distortion); (b) that the Spee’s curve and Wilson’s curve are appropriate for the planned restoration; (c) that the occlusal plane angle is acceptable relative to the Frankfort horizontal; (d) that in CR closure, the CR contacts appear where expected (on the cusp tips or on the fossae, not on proximal surfaces — unexpected proximal CR contacts indicate the CR record was incorrect or the impression was distorted). Any anomaly found at this stage should trigger re-impression and re-mounting before fabrication.
Common Mistakes & Misconceptions
- Misconception: “Centric relation is the most retruded position of the condyle.”
Correction: This was the older definition (pre-1990s GPT terminology) and is now explicitly outdated. The GPT-9 (2017) definition places the condyle in the most superior, anterior musculoskeletally stable position — not the most retruded. Retrusion of the condyle is associated with posterior slope of articular eminence contact, potential bilaminar zone compression, and TMD symptoms. The bimanual manipulation technique guides the condyle superiorly and anteriorly, not posteriorly. - Misconception: “A facebow is unnecessary for simple single-unit crowns.”
Correction: For truly straightforward cases (a single posterior crown with no complex occlusal geometry, in a patient with ample posterior tooth support, who will undergo occlusal adjustment on delivery) a facebow is commonly omitted in routine practice — and this can be acceptable clinically. However, for any case involving multiple units, anterior teeth, full-mouth occlusal changes, or complete dentures, a facebow is not optional — it is required for accurate cast mounting. Additionally, students should know the purpose of the facebow for board exams even if its omission is sometimes clinically expedient in simple cases. - Misconception: “The protrusive record sets the Bennett angle.”
Correction: The protrusive record sets the condylar guidance angle (the inclination of the condylar path in the sagittal plane — how steeply the condyle descends the articular eminence during protrusion). The lateral record sets the Bennett angle (the medial movement of the non-working condyle during lateral jaw movement in the horizontal plane). This is a commonly confused distinction on board examinations. - Misconception: “Wax bite registrations are adequate for complex crown and bridge cases because any error can be adjusted intraorally.”
Correction: The premise — that intraoral adjustment compensates for registration errors — is technically true but clinically problematic. Adjusting occlusion intraorally by progressive grinding is irreversible and time-consuming. Using an inaccurate wax registration means the restoration is fabricated in an open-vertical or incorrectly positioned bite, requiring adjustment of the new restoration (destroying the original surface treatment and polish) or, in some cases, re-fabrication. PVS bite registration adds minimal time and cost but produces casts that articulate in the correct relationship, delivering a restoration that requires minimal or no occlusal adjustment — the clinical standard. - Misconception: “Non-working side contacts are always pathological and must be eliminated in every patient.”
Correction: Non-working side (balancing side) contacts are pathological in natural dentition and in fixed prosthodontic restorations — they must be eliminated in these situations. However, for complete dentures, bilateral balanced occlusion — which deliberately includes non-working side contacts — is the appropriate occlusal scheme. Without non-working contacts in complete dentures, lateral forces during chewing would cause the denture to tip around the occlusal contact fulcrum, dislodging it. The non-working contacts prevent this tipping by distributing forces bilaterally. This is the one clinical situation where non-working contacts are not only acceptable but necessary.
Related Topics
References & Sources
- The Glossary of Prosthodontic Terms — 9th Edition (GPT-9) (2017). Journal of Prosthetic Dentistry, 117(5S):e1–e105. Academy of Prosthodontics. [Definitive terminology source — CR definition, jaw relation terms, articulator classification, occlusal terminology]
- Dawson PE (2007). Functional Occlusion: From TMJ to Smile Design. Mosby/Elsevier. [Comprehensive reference on centric relation, bimanual manipulation, occlusal analysis, and treatment planning in CR]
- Okeson JP (2019). Management of Temporomandibular Disorders and Occlusion, 8th ed. Elsevier. [Standard TMD and occlusion text — CR definition, articulator use, occlusal interference classification, splint therapy]
- Hanau RL (1926). Occlusal changes in centric relation. Journal of the American Dental Association, 13(4):610–621. [Original publication of Hanau’s Quint — the five determinants of occlusion applied to complete dentures]
- Posselt U (1952). Studies in the mobility of the human mandible. Acta Odontologica Scandinavica, 10(Suppl 10):1–160. [Classic study establishing the envelope of motion and terminal hinge axis — foundational for articulator design and CR theory]
- Keshvad A, Winstanley RB (2000). An appraisal of the literature on centric relation. Part I. Journal of Oral Rehabilitation, 27(10):823–833. [Review of historical and contemporary CR definitions — supports the evolution from retruded to superior-anterior GPT-9 definition]
- Shillingburg HT, Hobo S, Whitsett LD, et al. (1997). Fundamentals of Fixed Prosthodontics, 3rd ed. Quintessence. [Standard fixed prosthodontics text — articulator selection, facebow use, occlusal record techniques, occlusal schemes]
- Williamson EH, Lundquist DO (1983). Anterior guidance: its effect on electromyographic activity of the temporal and masseter muscles. Journal of Prosthetic Dentistry, 49(6):816–823. [Classic study demonstrating that canine guidance produces significantly less posterior muscle activity than group function — supporting canine-guided occlusion as protective for posterior teeth]
Summary
Occlusal records transfer patient-specific jaw relationships to an articulator so that indirect restorations can be fabricated with accurate occlusal contacts. The four key records are: the facebow (relates maxillary arch to the transverse hinge axis — required for Class III/IV articulators), the CR record (positions mandibular cast relative to maxillary at the reproducible, joint-guided reference position — not tooth-guided MIP), the protrusive record (sets condylar guidance angle), and the lateral record (sets Bennett angle). CR is defined by GPT-9 as the most superior, anterior, musculoskeletally stable condylar position — not the retruded position. Bimanual manipulation (Dawson technique) is the standard CR recording method, often preceded by anterior deprogramming (Lucia jig) to eliminate the MIP muscle engram. PVS bite registration is the most accurate material; wax is the least accurate and should not be used for complex restorations. Semi-adjustable (Class III) articulators are the clinical standard for FPD, implant prosthetics, and full-mouth rehabilitation — fully adjustable (Class IV) articulators are reserved for complex gnathological cases. Non-working side contacts are pathological in natural dentition and fixed prosthodontics but are the essential design feature of complete denture bilateral balanced occlusion.
Key Takeaways
- CR definition (GPT-9): Most superior, anterior, musculoskeletally stable condylar position — NOT retruded. Reproducible, joint-guided. Bimanual manipulation (Dawson) guides condyle superiorly + anteriorly. Anterior deprogrammer (Lucia jig) eliminates MIP engram before recording.
- Articulator classes: I = hinge only; II = average-value fixed settings; III = semi-adjustable (clinical standard — requires facebow + CR record + protrusive record + lateral record); IV = fully adjustable (pantograph, kinematic facebow — complex cases only).
- What each record sets: Facebow → maxillary cast to hinge axis. CR record → mandibular cast to maxillary cast. Protrusive record → condylar guidance angle. Lateral record → Bennett angle.
- Bite registration accuracy: PVS = highest (gold standard); ZOE paste = high (good for edentulous); polyether = high; wax = lowest (avoid for complex cases — creeps and distorts).
- Interferences: NWS (non-working side) interference = most damaging to natural dentition (lever effect on working condyle); WS interference = less damaging. EXCEPTION: NWS contacts are required and desirable in complete dentures (bilateral balanced occlusion prevents denture tipping).
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