DENTAL TECHNIQUE

Digital recording of a conventionally determined centric

relation: A technique using an intraoral scanner
Michael Radu, DDS, MS,a Daniel Radu, DMD,b and Marcus Abboud, DDS, PhDc

Centric relation (CR) ABSTRACT

recording is an important
This article describes a technique for digitally recording centric relation using an intraoral scanner
step in many dental pro- based on conventional clinical procedures and discusses the advantages and disadvantages of such
cedures. CR is defined by the a recording. (J Prosthet Dent 2020;123:228-31)
ninth edition of the Glossary
of Prosthodontic Terms1 as “a maxillomandibular rela- recording of CR using intraoral digital scanners. The
tionship, independent of tooth contact, in which the purpose of this article was to describe a technique for the
condyles articulate in the anterior-superior position direct digital recording of CR using an intraoral scanner.
against the posterior slopes of the articular eminences; in The technique can be used in various clinical situations,
this position, the mandible is restricted to a purely rotary such as while using occlusal devices or fixed complete
movement; from this unstrained, physiologic, max- dentures, and incorporates the recording at the desired
illomandibular relationship, the patient can make verti- occlusal vertical dimension (OVD).
cal, lateral or protrusive movements; it is a clinically
useful, repeatable reference position.” TECHNIQUE
CR can be recorded with bimanual manipulation2 or the
anterior device technique.3-5 The device can be a leaf gauge, The authors present the steps followed in finding and
an anterior deprogrammer, or a composite resin stop. The recording CR for 2 clinical applications using a dental
anterior device technique relaxes the lateral pterygoid intraoral scanner.
muscles and positions the condyles in CR by ensuring that
the patient contracts the elevator muscles. These tech- With a leaf gauge
niques are well documented and relatively straightforward
to use.6,7 Traditionally, CR is recorded with wax wafers, wax 1. Scan the patient’s maxillary and mandibular arches
rims on base plates, or polyvinyl siloxane pastes. to obtain digital casts using an intraoral scanner
With the introduction of contactless intraoral 3D (TRIOS 3; 3Shape).
scanning, new techniques for CR recording have 2. Determine the number of leaves needed to obtain a
emerged. Importing an analog occlusal record into a space of about 1 mm between the posterior teeth to
software program and using it with a virtual articulator allow the digital design of an occlusal device without
have been described,8,9 as well as the digital complete opening the virtual articulator on an arbitrary hinge
denture workflow,10 virtual occlusal recording of axis. In the patient shown in Figure 1, 25 leaves
the maximal intercuspal position,11 and jaw relation re- were used.
cords for the fabrication of an occlusal device.12 However, 3. Ask the patient to move the mandible forward and
the authors are unaware of publications on the direct then backward. Repeat this 2 or 3 times. When the

a
Adjunct Assistant Professor, Department of Restorative Dentistry, College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, Fla; and Private practice,
Boca Raton, Fla.
b
Private practice, Boca Raton, Fla.
c
Professor and Associate Dean for Digital Dentistry, College of Dentistry, University of Kentucky, Lexington, Ky.

228 THE JOURNAL OF PROSTHETIC DENTISTRY

February 2020 229

Figure 1. Leaf gauge used to find centric relation at desired occlusal Figure 2. Centric relation recording using intraoral scanner.
vertical dimension.

mandible reaches the backward position, ask the

patient to clench and hold that position. This
mandibular position can be considered to be CR.
4. Place the head of the intraoral scanner on the right
side of the arches and record the interarch rela-
tionship and then repeat the same on the left side
(Fig. 2). The TRIOS 3 software creates the occlusal
record, with the mandible placed in CR at the
determined OVD (Fig. 3).
5. Upload the digital casts and occlusal record scans
into the CAD-CAM software (Dental System;
3Shape). Use the data for designing and fabrication
of the occlusal device.
Figure 3. TRIOS 3 software matching digital casts of arches to side view
interarch scan (shown in light blue).
With a composite resin stop

1. Scan the prepared teeth and the opposing arch

DISCUSSION
(Fig. 4).
2. Determine the desired OVD and fabricate a small CR is a clinically useful reference maxillomandibular
composite resin stop on an anterior tooth (Fig. 5). relationship. The authors have used the established
Make the device out of a light-polymerized com- conventional technique of finding CR with the help of an
posite resin (Filtek Supreme Ultra; 3M ESPE); make anterior device. This technique stabilizes the mandible,
it oversized at first and reduce it gradually to the which is a prerequisite for digital recording. The mandible
desired height so as to have sufficient occlusal is stable because of the tripod created between the 2
clearance for the design of the fixed prostheses condyles seated in the anterior-superior position against
(Fig. 6). the posterior slope of the articular eminences and the
3. Ask the patient to move the mandible forward and anterior device.
then backward; adjust the device using a diamond The conventional technique requires a recording
rotary instrument (KS4; Brasseler) to allow for a medium (wax, polyvinyl siloxane) to be interposed be-
smooth movement of the mandible. Repeat this 2 or 3 tween the arches while positioning the mandible in CR.
times. When the mandible reaches the backward po- Interpositioning of any material in between the teeth
sition, ask the patient to clench and hold that position. may lead the patient to avoid it, thereby skewing the
This mandibular position is considered to be CR. recording. The record itself may distort during trans-
4. Repeat steps 4 and 5 of the leaf gauge technique to portation to the laboratory. The laboratory step of
obtain a digital CR record and upload it into the fitting the occlusal record onto the stone casts and
CAD-CAM software (Fig. 7). Use the data to fabri- mounting the assembly in the articulator is also prone
cate the fixed prostheses. to error.

Radu et al THE JOURNAL OF PROSTHETIC DENTISTRY

230 Volume 123 Issue 2

Figure 4. Digital scans. A, Mandibular prepared teeth. B, Opposing maxillary arch.

Figure 5. Composite resin stop on mandibular central incisor. Figure 6. Composite resin stop at desired occlusal vertical dimension to
stabilize mandible in centric relation.

Digital recording has several advantages with regard

to efficiency and accuracy. The recording takes place
without an interposed medium. Uploading of the
digital casts into the software in the CR position hap-
pens without the need for positioning physical stone
casts by the dental laboratory technician. This ensures
an accurate and efficient mounting in the virtual
articulator.
The direct digital occlusal recording is based on the
intraoral scanner software matching the digital casts of
the arches to the interarch scan obtained from the side
view of the arches. This makes the anterior device a
valuable tool that stabilizes the mandible and does not
obstruct the side view of the intraoral scanner.
The anterior device technique appears to be more Figure 7. Digital centric relation recording at desired occlusal vertical
straightforward and less prone to errors than similar dimension.
techniques12 because the mandible is more stable when
supported by an anterior device rather than a lateral
SUMMARY
device.
Disadvantages of the direct digital recording include This article describes a technique for direct digital
the cost of acquiring the intraoral scanner and its asso- recording of CR using an intraoral scanner. Conven-
ciated learning curve. tional methods were used to determine CR and stabilize

THE JOURNAL OF PROSTHETIC DENTISTRY Radu et al

February 2020 231

the mandible at the desired OVD. An intraoral scanner 7. McKee JR. Comparing condylar positions achieved through bimanual
manipulation to condylar positions achieved through masticatory muscle
was used to record that position relating the right and contraction against an anterior deprogrammer: A pilot study. J Prosthet Dent
left posterior areas of the arches. The clinical applica- 2005;94:389-93.
8. Qu F, Du X, Liu WC. 3D printed custom trays with a Gothic arch for centric
tions depicted are the use of a leaf gauge for the relation recording and definitive impression making for complete denture: A
fabrication of an occlusal device and an anterior com- dental technique. J Prosthet Dent 2019;121:32-6.
posite resin stop for fixed prostheses. This technique 9. Lo Russo L, Salamini A. Removable complete digital dentures: A
workflow that integrates open technologies. J Prosthet Dent 2018;119:
allows for a straightforward and accurate recording of 727-32.
CR at the desired OVD and transferring it to a virtual 10. Fang JH, An X, Jeong SM, Choi BH. Development of complete dentures
based on digital intraoral impressions-Case report. J Prosthodont Res
articulator. 2018;62:116-20.
11. Solaberrieta E, Arias A, Brizuela A, Garikano X, Pradies G. Determining the
requirements, section quantity, and dimension of the virtual occlusal record.
REFERENCES J Prosthet Dent 2016;115:52-6.
12. Dedem P, Turp JC. Digital Michigan splint e from intraoral scanning to
1. The glossary of prosthodontic terms: Ninth Edition. J Prosthet Dent 2017;117: plasterless manufacturing. Int J Comput Dent 2016;19:63-76.
e1-105.
2. Dawson PE. Functional occlusion: From TMJ to smile design. 1st ed. St.
Louis: Mosby/Elsevier; 2006. p. 76-80.
Corresponding author:
3. Lucia VO. A technique for recording centric relation. J Prosthet Dent 1964;14:
492-505. Dr Michael Radu
4. Long JH Jr. Location of the terminal hinge axis by intraoral means. J Prosthet 1865 NW Boca Raton Blvd.
Dent 1970;23:11. Boca Raton, FL 33432
5. Jayne D. A deprogrammer for occlusal analysis and simplified accurate case Email: mradu@dentalart.com
mounting. J Cosmetic Dent 2006;21:96-102.
6. Woelfel JB. New device for accurately recording centric relation. J Prosthet Copyright © 2019 by the Editorial Council for The Journal of Prosthetic Dentistry.
Dent 1986;56:716-27. https://doi.org/10.1016/j.prosdent.2018.12.004

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