Interocclusal Records: Accuracy and Reproducibility in Occlusion and Functional Dynamics

How do you know that the jaw relationship on the screen or articulator is the one you intended to record? A convincing-looking occlusion is not enough. Separate three questions: whether the individual arches were captured faithfully, whether they were related correctly, and whether that relationship can be recorded again. Digital and conventional methods can both contribute, but their results must be interpreted for the indication and the measurement actually studied.

This DDS guide connects those distinctions to the decisions made by the dentist and laboratory. The aim is a record that can be checked and communicated, without turning a scanner specification or a laboratory experiment into a promise about the finished restoration.

Which jaw relationship are you trying to transfer?

Start with the intended reference position. Maximal intercuspal position (MIP) describes the best interdigitation of opposing teeth, independently of condylar position. Centric relation (CR) is a jaw relationship defined independently of tooth contact and used as a repeatable clinical reference. They are different concepts; a buccal scan taken while the patient closes into MIP does not establish CR. The Glossary of Prosthodontic Terms 2023 defines both terms. [1]

For the prescription, specify the position being transferred, the intended vertical relationship, and whether the existing intercuspation is being maintained or a different relationship is being planned. If the intended position cannot be reproduced comfortably, resolve that clinical question before treating a digital alignment as the answer. A colour map cannot select the treatment position for you.

Why is impression accuracy different from bite-record accuracy?

An impression or arch scan represents the shape of an arch. An interocclusal record relates two arches. Good surface capture is necessary, but it does not by itself validate the relative position of the maxilla and mandible. Trueness concerns agreement with a reference; precision concerns agreement among repeated measurements. Repeatedly obtaining the same alignment does not prove that it is true.

Ender and Mehl’s 2013 investigation measured the trueness and precision of complete-arch impressions against a steel reference model. It was an in-vitro impression study, not a 2020 systematic review of interocclusal records. Its surface-deviation findings cannot be used to rank bite-registration materials or establish CR-record accuracy. [2]

Read an accuracy claim by asking what was measured: an individual scan surface, the relative position of articulated arches, contact detection, or the occlusal adjustment of a delivered restoration. These endpoints answer different questions. A single micrometre value without its reference, method and clinical context is not a useful scanner ranking.

What do clinical studies actually tell us?

Repeatability of a static relationship

Morsy and El Kateb compared digital and conventional static registrations in nine participants with complete natural dentitions. The digital workflow used a Medit i700; the conventional workflow included PVS impressions, casts, silicone bite records, mounting and laboratory scanning. Each articulation was repeated three times. The table reports study-specific mean ± standard deviation of repeated-model discrepancies; smaller values indicated better precision. [3]

The digital workflow was more precise within this experiment. Differences between full-arch and quadrant registrations within each method were not statistically significant. The authors could not assess trueness without an in-vivo reference standard. These findings do not validate every scanner, CR registration, edentulous rehabilitation or final restoration, and the conventional result reflects the whole tested workflow rather than the bite material alone. [3]

Finding contacts is a separate task

In a ten-participant clinical study, Abdulateef and colleagues compared virtual records with sites identified on transilluminated PVS records. Sensitivity was 87% and specificity 95% for classifying the selected sites. Only 74% of close-proximity sites were consistently identified across all three repeated scans. The authors also observed that virtual casts could intersect. These are contact-identification and repeatability findings, not a percentage probability of treatment success or a measure of bite force. [4]

Botsford and colleagues studied two bite registrations in 20 participants using one scanner system. Agreement was moderate for contact location, while contact size and software-coded intensity showed weak correlations. The study did not establish agreement with the participants’ actual occlusion. The practical lesson is to inspect the complete record and its repeatability rather than accepting a familiar colour pattern as proof. [5]

What changes when teeth or stable landmarks are missing?

The accuracy of a virtual jaw relationship depends on the situation being registered. Ren, Morton and Lin tested five cast configurations with one scanner. A single missing posterior tooth performed comparably to the dentate reference at the evaluated edentulous location, whereas extended posterior and anterior spaces affected accuracy. This was an in-vitro study, so it should guide caution rather than prescribe a universal tooth-count cutoff. [6]

For a long edentulous span, ask how the relationship is supported and how it will be checked independently. Do not extend a result from fully dentate MIP records to an unsupported edentulous registration. If the opposing arches appear tilted, intersect implausibly, or disagree with the clinical contact pattern, stop the design step and reassess the arch scans, registration surfaces and patient closure. Depending on the case, additional supported records or another registration method may be needed.

How should conventional materials be judged?

A recording material has to permit the intended closure before setting and resist distortion during removal, handling and mounting afterward. Low resistance before setting and resistance to compression after setting are different requirements. “Soft” is not a useful description unless the stage and purpose are clear.

Ghazal, Albashaireh and Kern tested six materials in an apparatus simulating the jaws, with measurements after one and 48 hours. The tested elastomers produced smaller vertical discrepancies than the two waxes; differences among the tested elastomers were not statistically significant. This 2008 experiment supports a material-and-handling comparison under defined conditions, not a universal claim that every PVS product is more accurate than every polyether. [7]

A separate Ghazal, Hedderich and Kern experiment, published in 2017, measured displacement at an articulator’s condylar-position indicator after cast mounting. Recording material, technique and storage time affected that laboratory result. It did not measure a patient’s condylar displacement or establish a cause of temporomandibular disorder. The best-performing corrected resin technique in that experiment should not be turned into an automatic prescription for every patient. [8]

Clinically, choose a material and support appropriate to the intended registration, then follow the exact product’s current instructions for handling, setting, disinfection and storage. Check that the set record seats positively on the relevant teeth or casts without rocking or unintended interference. If it does not seat consistently, correct the source of the discrepancy and obtain a new record rather than forcing the casts together. These are practical verification principles, not a replacement for a product-specific protocol.

What can a digital contact display say about function?

A static bite scan describes one recorded relationship. A virtual articulator may simulate movement using selected parameters; measured patient movement requires its own acquisition and registration. For example, exocad’s Jaw Movement documentation describes importing patient-specific movement through an enabled module and aligning the associated scans. A static record alone does not contain that movement history. [9]

Likewise, exocad’s Show Distances display represents geometric contact, intersection or clearance, with a configurable colour scale. It does not directly measure occlusal force. Dedicated pressure or timing sensors are a separate measurement category; their output must be interpreted according to their own capabilities and clinical evidence. Do not infer bruxism, joint disease or a need for irreversible adjustment from scanner contact colours alone. [10]

When exchanging a dynamic case with the laboratory, distinguish the recorded static position, measured movement files and software simulation settings. Document which elements are patient-specific. A simulated excursion can help examine a design, but it does not guarantee adaptation, absence of adjustment or long-term stability.

How do these distinctions change a clinical decision?

Teaching example: a localized restoration with stable intercuspation. This is an illustrative decision, not a reported patient outcome. If the intention is to preserve MIP, compare the captured relationship with the clinically observed contacts. An unexpected open side or an apparent intersection calls for checking closure and registration before manufacture. The nine-participant precision study offers evidence about one static workflow; it does not promise a restoration requiring no adjustment. [3]

Teaching example: extensive reconstruction with an uncertain reference position. A more detailed scan cannot resolve an undefined jaw relationship. Establish and document the intended reference clinically, assess whether it can be repeated, and communicate the supporting records. Studies of dentate static MIP registration do not validate a particular CR manipulation method, deprogramming duration or vertical-dimension change. Nor do they justify a universal micrometre threshold that predicts pain or a fixed number of minutes of adjustment.

What should the dentist and laboratory do next?

1. Specify the relationship. Name the intended position and vertical relationship. Treat a change in either as a clinical decision requiring its own rationale, not a software default. [1]
2. Match the evidence to the case. Separate impression-surface accuracy, repeated articulation and contact detection. State the dentition, scanner or material, and endpoint before applying a published number. [2] [3] [4]
3. Check the record before designing. The dentist should compare the registration with clinical findings; the laboratory should inspect seating or virtual alignment and query discrepancies. Missing landmarks and inconsistent repeated records deserve particular attention. [5] [6]
4. Keep function and outcome separate. Identify which movement data were measured and which were simulated, and assess the delivered restoration clinically. No result cited here establishes a universal adjustment-free, symptom-free or long-term outcome. [9] [10]

The useful question is not simply whether a record is digital or conventional. It is whether the chosen method captures the intended relationship, whether discrepancies can be detected, and whether the dentist and technician understand the limits of the information being transferred.

References