CLINICAL RESEARCH

Accuracy of digital and conventional systems in locating occlusal ]]

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contacts: A clinical study

Bernat Rovira-Lastra, DDS, PhD,a Laura Khoury-Ribas, DDS, PhD,a Elan-Ignacio Flores-Orozco, DDS, PhD,b
Raul Ayuso-Montero, DDS, PhD,c Akhilanand Chaurasia, BDS, MDS, PhD,d and
Jordi Martinez-Gomis, DDS, PhDe

Mastication is the main function ABSTRACT

of the oral system, with occlusal
Statement of problem. The accuracy of methods used for locating occlusal contacts throughout
force and dental occlusion key the entire clinical procedure has been poorly studied.
factors.1-3 Clinical practice often
requires modifications to the Purpose. The purpose of this clinical study was to determine the reproducibility and criterion
dental occlusion for restorative validity for different methods of locating occlusal contacts.
or prosthetic treatment.4,5 Al­ Material and methods. Thirty-two adults with natural dentitions participated in this cross-sectional
though most patients adapt to test-retest study. In total, occlusal contacts at maximum intercuspation were recorded by using
their new occlusion easily, a few 15 methods: silicone transillumination with Occlufast Rock (40, 50, 100, and 200 µm) and Occlufast CAD
can develop discomfort and (40 and 50 µm); virtual occlusion (100, 200, 300, and 400 µm); articulating film (12-, 40-, 100-, and
even pain, especially in the 200-µm-thick); and T-Scan III. Images of the occlusal records were scaled and calibrated spatially, and the
occlusal contacts of the right posterior mandibular teeth were delimited by using the FIJI software
presence of an occlusal inter­
program. Reproducibility was expressed as 95% confidence intervals (95% CI) of the percentage of
ference.6 Therefore, occlusion agreement in the location of the occlusal contacts between images from the test sessions against retest
analysis systems should meet sessions using the same method. Criterion validity was expressed as 95% CI of the percentage of
minimal accuracy standards to agreement in the location of the occlusal contacts between images from the test sessions against
detect, quantify, and locate oc­ images from Occlufast Rock (criterion standard).
clusal contacts.
Results. Occlufast Rock achieved 85% to 95% agreement in the location of the occlusal contacts
Articulating film has been between the 2 sessions, whereas Occlufast CAD, 200-µm articulating film, and T-Scan offered
the most widely used system 79% to 86%, 68% to 75%, and 65% to 75% agreement, respectively. The most valid method was
because it is economical, avail­ Occlufast CAD (74% to 80%) followed by the 200-µm articulating film (57% to 63%), 400-µm virtual
able in different thicknesses, and occlusion (53% to 62%), 100-µm articulating film (52% to 60%), and T-Scan (48% to 56%).
allows rapid location of occlusal Conclusions. Conventional methods, such as 100- and 200-µm articulating film and digital
contacts.7-9 However, silicone methods, including 400 µm virtual occlusion and T-Scan, offer sufficient accuracy in locating the
occlusal registration, scanned occlusal contacts. However, strategies are needed to improve accuracy. (J Prosthet Dent
with a light source and analyzed 2024;132:115-122)

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflict of interest: None.
a
Assistant Professor, Department of Odontostomatology, Faculty of Medicine and Health Sciences, University of Barcelona, Barcelona, Catalonia, Spain.
b
Associate Professor, Department of Prosthodontics, Faculty of Dentistry, Autonomous University of Nayarit, Tepic, Mexico.
c
Associate Professor, Department of Odontostomatology, School of Dentistry, Faculty of Medicine and Health Sciences, University of Barcelona, Campus de Bellvitge
08907 L′Hospitalet de Llobregat, Barcelona, Catalonia, Spain.
d
Associate Professor, Department of Oral Medicine and Radiology, King George's Medical University, Lucknow, India.
e
Associate Professor, Serra Hunter Fellow, Department of Odontostomatology, Faculty of Medicine and Health Sciences, University of Barcelona, Barcelona, Catalonia,
Spain; and Researcher, Oral Health and Masticatory System Group (Bellvitge Biomedical Research Institute) IDIBELL, L′Hospitalet de Llobregat, Barcelona, Catalonia,
Spain.

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dental prostheses, extensive restorations, severe malocclu­

Clinical Implications sion, periodontal disease, excessive tooth wear, orofacial
The accuracy of occlusal contact location depends pain, or active orthodontic treatment were excluded. All
mainly on the occlusal system and interocclusal participants were fully informed and signed the written
informed consent form before participating in the study.
distances used. Although these methods are
clinically acceptable, the accuracy of conventional The Ethics Committee of Barcelona University Dental
methods can be improved with new protocols for Hospital approved the informed consent form and the study
clinical and interpretation procedures, while digital protocol (Ref. 11/2020). All procedures were conducted in
methods could benefit from improved software accordance with the principles of the Helsinki Declaration,
programs. and the study was reported in accordance with the
strengthening the reporting of observational studies in
epidemiology (STROBE) guidelines.
by using an image software program, has been reported to A single operator (B.R.-L.), with more than 10 years
of clinical experience, performed all clinical procedures
offer the highest reliability and validity for determining the
occlusal contact area (OCA)10-14 and has been claimed to be with participants seated in a dental chair at the 90-de­
the criterion standard method.12 Recently introduced digital gree position with their Frankfort plane parallel to the
floor. The participant’s age and sex were recorded, and
systems, including the T-Scan and digital casts, have also
become available for occlusal assessment.15-17 the distance between the most distal points of the
Static occlusal analysis comprises 3 steps. First, the pa­ mandibular canines was measured with digital calipers
(Absolute; Vogel) to calibrate the scale for image pro­
tient closes in the maximum intercuspation position while
an articulation indicator, a silicone material, or a sensor is cessing. The operator ensured the occlusal surfaces had
placed in this position or scans are made with an intraoral no debris before performing the occlusal recordings with
8 different systems in a random order determined with
scanner. Second, the dentist interprets the occlusal records
by examining the marks intraorally or with a software permuted blocks established with a web-based software
program. Third, the occlusal record can be stored and program (http://www.randomization.com). Half of the
participants were assigned to 1 of the 2 sequences and
transferred. However, each step can introduce variability
and error that affects the results. Although studies have rested for 2 minutes between occlusal records to avoid
assessed the reliability and validity of different occlusal muscle fatigue. To determine the reliability of the oc­
clusal methods, all occlusal records were repeated once
methods,7,18-24 few have analyzed all steps.10,12
Most researchers have focused on the number of for each participant in a retest session, following the
occlusal contacts and the OCA,10,12,20 whereas the lo­ same sequence and at the same time of day, 2 weeks
after the test session.
cation of those contacts is often more relevant in clinical
practice.9,18,19,25-27 The reliability or reproducibility, In system Occlufast Rock, a polyvinyl siloxane oc­
concerning the extent to which scores remain un­ clusal registration material (Occlufast Rock; Zhermack)
was applied to the occlusal surfaces of the mandibular
changed over time, are key to the accuracy of an occlusal
method.28 Criterion validity, defined as how well loca­ teeth. Participants were asked to occlude with maximum
tion with a given method agrees with that for the cri­ force at the maximum intercuspation position for
1 minute. System Occlufast CAD was comparable with
terion standard, is also useful.28 Unfortunately, reports
on the accuracy of methods for locating occlusal contacts system Occlufast Rock but used a scannable polyvinyl
throughout the entire clinical procedure are sparse. siloxane material (Occlufast CAD; Zhermack). Both oc­
clusal registrations were trimmed and scanned by using
The purpose of this clinical study was to determine the
criterion validity of different digital and nondigital occlusal the transparent materials adapter of a flatbed scanner
methods for locating occlusal contacts by using the (HP Scanjet G4050; Hewlett Packard).
For systems Articulating Film 12, 40, 100, and 200 µm,
Occlufast Rock transillumination system for reference. The
reproducibility of different occlusal methods in locating the the participants were asked to close their mouth firmly 3
occlusal contacts was also assessed. The null hypothesis was times while the operator placed 12-µm (Black and Red,
Arti-Fol Metallic Shimstock-Film; Bausch), 40-µm (Blue,
that different methods would have similar criterion validity
for locating occlusal contacts. Arti-Check Micron-Thin; Bausch), 100-µm (Blue, Progress
100 µm; Bausch), or 200-µm (Blue, Articulating Paper BK01;
Bausch) articulating film on each hemiarch held by 2 Miller
forceps (Forceps f. articulating paper Miller; Carl Martin).
MATERIAL AND METHODS
Before placing the films, cheek retractors (Spandex; Hager
This cross-sectional test-retest study recruited 35 adult Worldwide) were inserted, saliva was suctioned with a
predoctoral dental students with a minimum of 24 standard saliva ejector (Monoart; Euronda), and the occlusal
natural teeth, without edentulous spaces. Those with surfaces were air dried with an air-syringe. After removing

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July 2024 117

the film, the marks on the assessed mandibular arch were dynamic record of the mandibular arch at maximum
scanned (TRIOS 3; 3Shape A/S). Before every occlusal test, intercuspation. For the virtual occlusion system, 4
the teeth were cleaned with a cotton roll and nylon brush images of the mandibular occlusal contacts were cap­
(Proclinic; Stoddard Manufacturing Co) to remove any oc­ tured at interocclusal distances of 100, 200, 300, and
clusal marks. 400 µm (Fig. 1). Each color image was calibrated spa­
System T-Scan used an occlusal analysis system (T- tially and by scale with a reference image for articulating
Scan III; Tekscan, Inc) to obtain occlusal records. film or virtual occlusion in the FIJI software program
Participants were instructed to close in the maximum (ImageJ; National Institutes of Health) (Supplemental
intercuspation position with maximum force on a 100- Fig. 1 and Supplemental Video 1, available online). The
µm sensor foil. The software program (T-Scan 10.0.28; reference image was first scale-calibrated with the
Tekscan, Inc) generated a dynamic report showing the known intercanine distances by using the FIJI software
relative occlusal force detected for each sensor. System program, before selecting and saving the occlusal peri­
Virtual Occlusion involved the intraoral scanning meter of the premolars and first to molars on the right in
(TRIOS 3; 3Shape A/S) of all teeth in the maxillary and regions of interest (ROI) format. All color images were
mandibular arches, together with the intermaxillary re­ transformed by using multiple points of equivalence on
lationship when the teeth closed in the maximum in­ the scale-calibrated reference image with the “trans­
tercuspation position. form” plugin, applying a similarity class transformation
For each participant, 1 image of the mandibular arch with the least squares transformation method. The se­
from each system was captured and saved in Joint lected occlusal perimeter (ROI file) was applied to the
Photographic Experts Group (JPEG) format (Fig. 1). For transformed image, cleaned, and saved as a spatially
the T-Scan system, an image was captured from the calibrated color image.

Original Scale- and spatial- Final black and

System
Image calibrated Image white Image
Original Scale- and spatial- Final black and
System
Image calibrated Image white Image
Occlufast
Rock Articulating
film 100 µm
40 µm 50 µm 100 µm 200 µm
Occlufast
CAD

Articulating
40 µm 50 µm
film 200 µm
Articulating
film 12 µm

T-Scan
Articulating
film 40 µm

A B

Original Scale- and spatial- Final black and

System
Image calibrated Image white Image
Virtual
Occlusion
100 µm

Virtual
Occlusion
200 µm

Virtual
Occlusion
300 µm

Virtual
Occlusion
400 µm
C
Figure 1. Image processing for occlusal records. A, Systems Occlufast Rock and Occlufast-CAD, Articulating film 12 and 40 µm. B, Systems
Articulating Film 100 and 200 µm, and T-Scan. C, System Virtual Occlusion. CAD, computer-aided design.

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118 Volume 132 Issue 1

Supplementary material related to this article can be Criterion standard Articulating

Occlufast Rock 200 µm film 200 µm
found online at doi:10.1016/j.prosdent.2023.06.036.
Each color image was then converted to a grayscale 8-
bit format showing the occlusal contacts as black marks Test Test

(Supplemental Fig. 2, available online). Occlufast Rock

Criterion validity.
images were converted to 8-bits and applied threshold Agreement between
Articulating film and
Criterion standard
values of gray levels of 183, 174, 146, and 111 to generate
images with contact areas at interocclusal distances of 40,
Re-Test Re-Test
50, 100, and 200 µm. The Occlufast CAD images were
converted to 8-bit images and threshold values of gray
levels of 38 and 31 were applied to obtain images with
contact areas at interocclusal distances of 40 and 50 µm,
Reproducibility.
respectively. These interocclusal distances were selected to Agreement
between Test
be comparable with the 40-, 100-, and 200-µm articulating and Re-test

films and T-scan. These threshold values for both silicone

materials were determined by using stepped wedges to Figure 2. False negatives, false positives, and agreement in occlusal
establish the relationship between the 256-grayscale and contact location between images. Red: Occlusal contact area (OCA) only
the silicone thickness.2 Images from the 12-µm articulating in reference/template image (false negatives). Green: OCA only in test/
film were converted to 8-bits with a threshold value of gray source image (false positives). Black: Coincident OCA between images
(true positives). Occlusal total contact area=red+green+black. OCA
levels of 105. The blue articulating marks of the 40-, 100-,
reference=red+black. Occlusal contact area test=green+black. False
and 200-µm articulating film were converted to grayscale
negatives (%)={[(total area)–(test area)]×100}÷(Reference area). False
by using the color threshold and the Commission Inter­ positives (%)={[(Total area)–(Reference area)]×100}÷(Test area).
nationale de l’Eclairage (CIE)Lab color space with Agreement (%)=100–[(false negatives)+(false positives)]÷2.
threshold values of 1 to 255, 0 to 255, and 0 to 130 for L*;
a*, and b*. Color on the T-Scan images was also converted
by using the color threshold, but with the hue–satur­ was multiplied by 100 to calculate the percentage of
ation–brightness (HSB) color space, and threshold values false positive (Fig. 2). The percentage of agreement in
of 112 to 255, 71 to 255, and 0 to 255 for hue, saturation, occlusal contact location was assessed as 100 minus the
and brightness. Pixels representing occlusal contact in the average between the false-negative and false-positive
virtual records were converted to black by using the color percentages for the method. The higher the percentage
threshold and CIELab color space with threshold values of of agreement, the better the criterion validity of the
100 to 246, 0 to 137, and 163 to 248 for L*, a*, and b*. method in locating occlusal contact compared with the
When converting the colored and spatially calibrated criterion standard. Finally, each occlusal record ob­
images to grayscale, the same colored and spatially cali­ tained in the retest session was calibrated (spatial and
brated image was added as an overlay with 90% trans­ for scale) against the registration obtained in the ori­
parency to correct the occlusal mark boundaries with the ginal test for a given method, calculating the percen­
FIJI brush options if needed. tages of false negatives, false positives, and location
The OCAs on the grayscale images were measured agreement for occlusal contacts between test and
in mm2. The percentages of false-negative and false- retest. The reproducibility of each method in locating
positive contact areas were calculated for each method occlusal contact was expressed as the percentage of
by considering the Occlufast Rock as the criterion agreement between test and retest images. Image
standard (Fig. 2). Transillumination methods with sili­ processing and data analysis from the test and retest
cone-based material showed the highest accuracy in sessions were performed by a single researcher (J.M.-
determining the occlusal contact area.10-14 To calculate G.) with over 20 years of clinical experience. To assess
the percentage of false-negative, the grayscale image of the inter-rater reliability of the image processing and
a test method was overlaid with the grayscale image of interpretation of occlusal contact area, another re­
the criterion standard as a reference. The number of searcher (B.R.-L.) measured the OCA, percentage
black pixels in the reference image paired with white agreement against the criterion standard, and percen­
pixels in the test image divided by the number of black tage agreement between Occlufast Rock test and retest
pixels in either image was the fraction of false negative, sessions for 19 participants.
which was multiplied by 100 to calculate the percen­ Test-retest reliability for the OCA was assessed by
tage of false negative. Similarly, the number of black the intraclass correlation coefficient (ICC) for single
pixels in the test image paired with white pixels in the measurements, with a 2-way random effects model and
reference image divided by the number of black pixels absolute agreement.29 The inter-rater reliability only in
in either image was the fraction of false positive, which the image processing and occlusal interpretation parts of

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July 2024 119

the measurement process were also tested by using the The percentage of false negatives, false positives, and
ICC for the OCA, for the percentage agreement against agreement in occlusal contact location with different
the criterion standard, and for the percentage agreement occlusal methods and Occlufast Rock as the criterion
between Occlufast Rock sessions.29 A mean test-retest standard are shown in Table 2. Occlufast CAD showed
value was calculated for the OCA, agreement in occlusal the lowest percentages of false-negative and false-po­
contact location, and comparison of the different tech­ sitive occlusal contacts (18% to 30%) compared with
niques. All analyses were performed with a statistical similar interocclusal distances obtained by Occlufast
software program (IBM SPSS Statistics, v27; IBM Corp) Rock. Among the nontransillumination methods, only
(α=.05). 400-µm virtual occlusion and 200-µm articulating film
provided false negatives and positives below 50%
compared with the Occlufast Rock at 200 and 100 µm.
The highest agreement was found with Occlufast CAD,
RESULTS
followed by the 200-µm articulating film, 400-µm virtual
Among the 35 individuals examined, 3 were excluded (1 occlusion, 100-µm articulating film, T-Scan, 300-µm
woman had an interim restoration in the mandibular virtual occlusion, and 40-µm articulating film (Table 2).
right first molar, and 2 women had poor quality images Inter-rater reliability of percentage of agreement against
because of stitching defects in the virtual casts). The 32 the criterion standard were excellent for T-Scan and for
remaining participants (25 women and 7 men) had a virtual occlusion, good for articulating film, and poor to
mean age of 24.5 years (95% confidence interval, 23.1 to moderate for Occlufast CAD.
25.9) and a mean of 28.5 teeth (standard deviation, 1.4; Table 3 shows the percentages of false negatives, false
range, 25 to 32), and most had bilateral Angle class I positives, and agreement in occlusal contact location for
occlusion (n=20). Three participants in the test session each method between test and retest sessions. Transillu­
and 3 more in the retest session had at least 1 virtual mination with Occlufast Rock achieved agreement of 85%
occlusion record without an occlusal mark. to 95% in occlusal contact location between sessions,
Table 1 shows the OCAs for each system and inter­ whereas Occlufast CAD, 200-µm articulating film, and 400-
occlusal distance. Average contact areas in the right µm virtual occlusion offered agreements of 79% to 86%,
mandibular posterior teeth ranged from 4 mm2 with 68% to 75%, and 56% to 74%, respectively. Occlufast Rock
virtual occlusion (100 µm) to 79 mm2 with the T-Scan. was rated to have excellent interrater reliability (ICC>0.9) for
The test-retest reliability of the Occlufast Rock was ex­ measuring the percentage of agreement between sessions
cellent for measuring the OCA, whereas the T-Scan, by the same method.
Occlufast CAD, and articulating films (40- and 100-µm-
thick) offered good reliability (Table 1). Occlufast Rock
and CAD, virtual occlusion, and T-Scan were rated as
DISCUSSION
having excellent inter-rater reliability (ICC>0.9) for
measuring the OCA, whereas the reliability of articu­ The accuracy of occlusal contact location was found to
lating films was good (ICC, 0.75 to 0.90). depend mainly on the occlusal system and interocclusal

Table 1. Mean occlusal contact areas of right posterior mandibular teeth by method and thickness or interocclusal distances with test-retest and
interrater reliability of methods used to measure occlusal contact areas
Method Occlusal Contact Area
Mean (mm2) Test-Retest Inter-rater
(95%CI) Reliability Reliability
ICC (95%CI) ICC (95%CI)
Occlufast Rock 40 µm 13.5 (10.7-16.3) 0.92 (0.84-0.96) 0.99 (0.98-1.00)
Occlufast Rock 50 µm 15.1 (12.0-18.1) 0.94 (0.88-0.97) 0.99 (0.98-1.00)
Occlufast Rock 100 µm 21.1 (17.1-25.1) 0.98 (0.96-0.99) 0.99 (0.98-1.00)
Occlufast Rock 200 µm 35.6 (30.0-41.3) 0.98 (0.96-0.99) 0.99 (0.98-1.00)
Occlufast CAD 40 µm 12.4 (10.0-14.7) 0.76 (0.54-0.88) 0.99 (0.97-1.00)
Occlufast CAD 50 µm 14.8 (12.0-17.6) 0.79 (0.61-0.89) 0.99 (0.96-0.99)
Virtual Occlusion 100 µm 4.0 (2.6-5.4) 0.33 (−0.02 to 0.61) 1.00 (0.99-1.00)
Virtual Occlusion 200 µm 12.7 (9.3-16.1) 0.55 (0.25-0.75) 1.00 (0.99-1.00)
Virtual Occlusion 300 µm 23.7 (18.6-28.9) 0.55 (0.25-0.75) 1.00 (0.99-1.00)
Virtual Occlusion 400 µm 37.0 (30.3-43.7) 0.55 (0.25-0.75) 1.00 (0.99-1.00)
Articulating film 12 µm 7.4 (5.9-8.8) 0.72 (0.50-0.58) 0.82 (0.43-0.94)
Articulating film 40 µm 18.7 (15.4-22.0) 0.83 (0.67-0.91) 0.77 (0.24-0.92)
Articulating film 100 µm 23.1 (19.3-26.9) 0.78 (0.60-0.89) 0.78 (−0.03 to 0.94)
Articulating film 200 µm 23.1 (19.5-26.8) 0.63 (0.38-0.80) 0.84 (0.14-0.96)
T-Scan 79.4 (65.7-93.2) 0.88 (0.75-0.94) 0.99 (0.96-0.99)
95%CI, 95% confidence interval; ICC, intraclass correlation coefficient.

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Table 2. Percentages of false negatives, false positives, and agreement with criterion standard for occlusal contact location of different occlusal
systems by thickness and interocclusal distance
Occlufast Rock 40 µm Occlufast Rock 50 µm
Measurement % of False- % of False- % of Agreement % of False- % of False- % of Agreement
Method Negative Positive With Standard Negative Positive With Standard
Contact Area Contact Area Contact Area Contact Area
Occlufast CAD
40 µm 25.6 (21-30) 21.7 (18-26) 76.4 (73-80) 30.3 (26-35) 17.8 (14-22) 75.9 (73-79)
50 µm 18.2 (14-22) 27.7 (24-32) 77.1 (74-80) 22.3 (18-26) 23.0 (19-27) 77.3 (74-80)
Virtual occlusion
100 µm 84.9 (80-90) 59.9 (54-66) 26.2 (21-31) 85.6 (81-91) 56.1 (50-62) 27.6 (23-32)
200 µm 65.7 (58-73) 65.5 (60-71) 34.2 (29-39) 66.4 (59-74) 62.3 (57-68) 35.4 (30-41)
300 µm 46.7 (39-54) 70.9 (67-75) 41.0 (36-46) 47.6 (40-55) 67.9 (64-72) 42.1 (37-47)
400 µm 31.0 (24-38) 75.6 (73-79) 46.5 (41-51) 31.8 (25-39) 73.0 (70-76) 47.4 (43-51)
Articulating film
12 µm 72.9 (68-77) 55.3 (50-60) 35.9 (32-40) 74.3 (70-78) 52.4 (47-57) 36.7 (33-40)
40 µm 44.6 (38-51) 63.8 (60-68) 45.8 (42-50) 46.5 (40-53) 60.7 (57-64) 46.4 (43-50)
100 µm 34.5 (27-42) 63.9 (60-68) 50.8 (46-56) 36.1 (29-43) 60.6 (56-65) 51.7 (47-57)
200 µm 31.1 (25-37) 61.7 (57-67) 53.6 (50-57) 32.5 (27-38) 58.2 (53-63) 54.6 (51-59)
T-Scan 19.7 (14-25) 86.4 (84-88) 47.0 (44-50) 20.6 (15-26) 84.9 (83-87) 47.3 (44-50)
Occlufast Rock 100 µm Occlufast Rock 200 µm
Measurement % of False- % of False- % of Agreement % of False- % of False- % of Agreement
Method Negative Positive With Standard Negative Positive With Standard
Contact Area Contact Area Contact Area Contact Area
Occlufast CAD
40 µm 45.9 (41-50) 9.4 (7-12) 72.4 (69-75) 66.6 (63-70) 3.3 (2-5) 65.1 (63-67)
50 µm 37.9 (33-43) 12.7 (10-16) 74.7 (72-78) 60.7 (57-65) 4.8 (3-6) 67.3 (65-70)
Virtual occlusion
100 µm 87.8 (84-92) 45.4 (38-52) 31.5 (26-36) 90.6 (88-94) 25.2 (18-33) 38.7 (34-43)
200 µm 69.2 (63-76) 51.3 (45-57) 39.4 (34-45) 74.7 (69-80) 31.2 (25-37) 46.2 (41-52)
300 µm 51.0 (44-58) 57.5 (53-62) 45.5 (40-50) 57.6 (51-64) 37.2 (33-42) 52.0 (47-57)
400 µm 34.8 (28-41) 63.5 (60-67) 50.5 (46-55) 40.9 (35-47) 43.3 (39-47) 57.3 (53-62)
Articulating film
12 µm 78.0 (75-82) 41.8 (37-47) 40.1 (36-44) 84.2 (82-87) 26.8 (23-31) 44.5 (42-47)
40 µm 53.5 (48-59) 51.3 (48-55) 47.6 (44-51) 64.3 (60-69) 35.0 (31-39) 50.3 (47-53)
100 µm 43.0 (37-49) 50.2 (45-55) 53.4 (49-58) 55.4 (51-60) 33.0 (28-38) 55.8 (52-60)
200 µm 38.6 (33-44) 46.7 (42-52) 57.4 (54-61) 52.1 (48-57) 28.5 (24-33) 59.7 (57-63)
T-Scan 23.3 (17-29) 79.4 (77-82) 48.7 (45-52) 28.8 (22-35) 67.2 (64-71) 52.0 (48-56)
Registrations obtained by transillumination method with Occlufast Rock and measured at different interocclusal distances used as reference. Data
reported as means (95% confidence intervals).

Table 3. False negatives, false positives, and agreement between test and retest registrations in occlusal contact location obtained by each method
Method % False-Negative Contact Area % False-Positive Contact Area % Agreement Between Sessions
Occlufast Rock 40 µm 11.9 (8.6-15.3) 13.7 (10.3-17.1) 87.2 (84.5-89.8)
50 µm 10.8 (7.8-13.8) 12.8 (9.4-16.2) 88.2 (85.5-90.8)
100 µm 8.0 (6.1-9.9) 10.2 (7.1-13.3) 90.9 (88.6-93.1)
200 µm 6.4 (4.9-7.9) 7.7 (5.5-9.9) 92.9 (91.4-94.5)
Occlufast CAD 40 µm 14.7 (11.0-18.5) 21.3 (15.5-27.0) 82.0 (78.8-85.3)
50 µm 14.8 (10.8-18.8) 19.2 (14.1-24.3) 83.0 (79.9-86.1)
Virtual Occlusion 100 µm 66.8 (55.0-78.6) 61.0 (47.9-74.1) 32.7 (23.0-42.4)
200 µm 47.2 (34.7-59.7) 48.3 (36.5-60.2) 49.8 (40.4-59.2)
300 µm 37.6 (25.7-49.6) 40.2 (29.2-51.2) 59.2 (49.9-68.4)
400 µm 32.3 (21.9-42.7) 33.3 (22.8-43.8) 65.1 (56.1-74.2)
Articulating film 12 µm 49.1 (42.8-55.3) 53.6 (46.5-60.7) 48.7 (43.8-53.6)
40 µm 41.4 (35.8-47.0) 42.5 (37.1-47.9) 58.0 (53.5-62.6)
100 µm 35.7 (29.5-42.0) 35.5 (31.0-40.0) 64.4 (60.6-68.2)
200 µm 26.7 (21.2-32.1) 30.7 (26.0-35.4) 71.3 (68.1-74.5)
T-Scan 26.2 (20.7-31.7) 33.1 (27.2-39.1) 70.3 (65.4-75.2)
Registrations from first session considered as reference images and those from retest session considered as test images. Data reported as means
(95% confidence intervals).

distances used. Therefore, the null hypothesis that mandibular positions during registrations) and mea­
different methods would have similar criterion surement errors (image processing). Thus, the present
validity for locating occlusal contacts was rejected. data support the continued use of silicone transillumi­
Transillumination with Occlufast Rock demonstrated nation as the criterion standard for analyzing occlusal
not only excellent reliability when measuring the OCA contacts.12 However, it was notable that transillumina­
but also excellent reproducibility in occlusal contact lo­ tion with Occlufast CAD did not improve the reliability
cation. The average 7% inaccuracy probably reflects the or reproducibility. The physical characteristics of this
sum of clinical variabilities, including participant differ­ material also made it impossible to detect occlusal
ences during the procedures (different forces and contacts with distances larger than 50 µm.

THE JOURNAL OF PROSTHETIC DENTISTRY Rovira-Lastra et al

July 2024 121

The T-Scan system showed good reliability in measuring dental students to optimize mandibular movements may
the OCA and an acceptable 70% agreement in occlusal have limited the extrapolation of the data to the whole
contact location between sessions. Nevertheless, dentists in population. In addition, only the posterior and the right
clinical practice must account for the high OCA, as also side of the mandible were assessed. Although no great
reported in other studies,10,12 and the high percentage of lateral asymmetries were expected,13,14 failure to con­
false-positive contacts (>67%) compared with transillumi­ sider anterior teeth might have increased the accuracy
nation with Occlufast Rock. Although the thickness and reported. Future studies should consider the occlusal
rigidity of the T-Scan sensor have been significantly im­ contacts of anterior teeth. Occlusal force was not mea­
proved since it was first introduced 35 years ago, the re­ sured objectively, and this probably increased the ob­
cently introduced sensors are not flexible enough to avoid served variability in occlusal contact location between
some false positives, especially in the areas where the sensor sessions and methods. Another limitation reflects the
flexes. An advantage of the T-Scan system is that it can physical differences between traditional and digital
measure relative occlusal forces over time, with its software methods, where there is no interposition of any material
program allowing the integration of digital scanning.15 Fu­ between the occlusal surfaces. The physical character­
ture studies should focus on improving the criterion validity istics of the occlusal registration methods such as ar­
and reproducibility of the T-Scan system for occlusal contact ticulating film, Occlufast Rock, and CAD and T-Scan
location. could modify the occlusal relationship between teeth
Virtual occlusion with an intraoral scanner offered poor compared with the intraoral scan registration, where
reliability for interocclusal distances of 100 or 200 µm, but there is no interference between occlusal surfaces.32
acceptable validity at 300 and 400 µm for occlusal contact
location compared with the Occlufast Rock at 200 µm. The
algorithms used to generate the 3D casts did not consider CONCLUSIONS
periodontal ligaments and tooth mobility when applying
Based on the findings of this clinical study, the following
occlusal force. Other studies have used an external software
conclusions were drawn:
program to relocate each segmented tooth to improve the
relationship between the maxillary and mandibular casts in 1. Using the Occlufast Rock transillumination system
the maximum intercuspation position.12,21,27 Such a soft­ as the criterion standard for assessing adults with
ware program could be incorporated with the intraoral scan natural dentitions, Occlufast CAD (74% to 80%)
kit to improve accuracy in occlusal contact location at 100 or was the most valid method for occlusal contact
200 µm. location, followed by 200-µm articulating film (57%
Articulating film at 100 and 200 µm showed similar to 63%), 400-µm virtual occlusion (53% to 62%),
OCAs to that obtained with Occlufast Rock considering 100-µm articulating film (52% to 60%), and T-Scan
at 100 µm. The 200-µm articulating film also provided (48% to 56%).
good reproducibility in occlusal contact location and 2. Reproducibility in occlusal contact location with
moderate validity compared with transillumination with Occlufast Rock was high (85% to 95%), followed by
Occlufast Rock at 50, 100, and 200 µm. However, both Occlufast CAD (79% to 86%), 200-µm articulating
the inter-rater reliability for OCA measurement and the film (68% to 75%), T-Scan (65% to 75%), 400-µm
construct validity for occlusal contact location were virtual occlusion (56% to 74%), and 100-µm ar­
lower than those obtained with digital systems. These ticulating film (61% to 68%).
results confirm the subjective natures of interpreting 3. Although these were clinically acceptable, the ac­
articulating film markings, where the accuracy of this curacy of conventional methods can be improved
method depends on whether chromatic intensity or with new protocols for clinical and interpretation
marks on the opposing teeth are considered.4,9,15 In procedures, while the digital methods could benefit
addition, this technique is sensitive to clinical changes, from including an additional software program.
with the possibilities of false negatives associated with
saliva and false positives because of contact with the
teeth during insertion.7,22 Therefore, how dentists place PATIENT CONSENT
the articulating film and how the patients move their
Informed patient consent has been obtained.
jaws can influence the accuracy of occlusal contact as­
sessment.23,24 Future studies should aim to enhance the
accuracy and efficiency of articulating film considering
APPENDIX A. SUPPORTING INFORMATION
both its clinical procedure and interpretation. Applying
artificial intelligence models could improve accuracy.30,31 Supplementary data associated with this article can be
This study included all clinical procedures for an found in the online version at doi:10.1016/j.prosdent.
assessment of variability and error. However, the use of 2023.06.036.

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122 Volume 132 Issue 1

REFERENCES 22. Saraçoǧlu A, Özpinar B. In vivo and in vitro evaluation of occlusal indicator
sensitivity. J Prosthet Dent. 2002;88:522–526.
1. Lee HS, Ko KH, Huh YH, Cho LR, Park CJ. Correlation between occlusal 23. Saad MN, Weiner G, Ehrenberg D, Weiner S. Effects of load and indicator
contact area at various levels of interocclusal thicknesses and masticatory type upon occlusal contact markings. J Biomed Mater Res - Part B Appl
performance. J Oral Rehabil. 2022;49:522–528. Biomater. 2008;85:18–22.
2. Lujan-Climent M, Martinez-Gomis J, Palau S, Ayuso-Montero R, Salsench 24. Kerstein RB, Radke J. Clinician accuracy when subjectively interpreting
J, Peraire M. Influence of static and dynamic occlusal characteristics and articulating paper markings. Cranio. 2014;32:13–23.
muscle force on masticatory performance in dentate adults. Eur J Oral Sci. 25. Davies S, Al-Ani Z, Jeremiah H, Winston D, Smith P. Reliability of recording
2008;116:229–236. static and dynamic occlusal contact marks using transparent acetate sheet.
3. Martinez-Gomis J, Lujan-Climent M, Palau S, Bizar J, Salsench J, Peraire M. J Prosthet Dent. 2005;94:458–461.
Relationship between chewing side preference and handedness and lateral 26. Arslan Y, Bankoğlu Güngör M, Karakoca Nemli S, Kökdoğan Boyacı B,
asymmetry of peripheral factors. Arch Oral Biol. 2009;54:101–107. Aydın C. Comparison of maximum intercuspal contacts of articulated casts
4. Mpungose S, Geerts G. Analyzing complete denture occlusal contacts: and virtual casts requiring posterior fixed partial dentures. J Prosthodont.
Accuracy and reliability. Int J Prosthodont. 2016;29:50–52. 2017;26:594–598.
5. Prieto-Barrio P, Khoury-Ribas L, Rovira-Lastra B, Ayuso-Montero R, 27. Li L, Chen H, Wang Y, Sun Y. Construction of virtual intercuspal occlusion:
Martinez-Gomis J. Variation in dental occlusal schemes two years after Considering tooth displacement. J Oral Rehabil. 2021;48:701–710.
placement of single-implant posterior crowns: A preliminary study. J Oral 28. Mokkink LB, Terwee CB, Patrick DL, et al. The COSMIN study reached
Implantol. 2022;48:110–116. international consensus on taxonomy, terminology, and definitions of
6. Avivi-Arber L, Lee JC, Sessle BJ. Dental occlusal changes induce motor measurement properties for health-related patient-reported outcomes.
cortex neuroplasticity. J Dent Res. 2015;94:1757–1764. J Clin Epidemiol. 2010;63:737–745.
7. Millstein P, Maya A. An evaluation of occlusal contact marking indicators: 29. Koo TK, Li MY. A guideline of selecting and reporting intraclass correlation
A descriptive quantitative method. J Am Dent Assoc. 2001;132:1280–1286. coefficients for reliability research. J Chiropr Med. 2016;15:155–163.
8. Bozhkova T, Musurlieva N, Slavchev D, Dimitrova M, Rimalovska S. 30. Krois J, Garcia Cantu A, Chaurasia A, et al. Generalizability of deep learning
Occlusal indicators used in dental practice: A survey study. Biomed Res Int. models for dental image analysis. Sci Rep. 2021;11:6102.
2021;2021:2177385. 31. Schwendicke F, Cejudo Grano de Oro J, Garcia Cantu A, Meyer-Lueckel H,
9. Brizuela-Velasco A, Álvarez-Arenal Á, Ellakuria-Echevarria J, del Río- Chaurasia A, Krois J. Artificial intelligence for caries detection: Value of data
Highsmith J, Santamaría-Arrieta G, Martín-Blanco N. Influence of and information. J Dent Res. 2022;101:1350–1356.
articulating paper thickness on occlusal contacts registration: A preliminary 32. Helms RB, Katona TR, Eckert GJ. Do occlusal contact detection products
report. Int J Prosthodont. 2015;28:360–362. alter the occlusion? J Oral Rehabil. 2012;39:357–363.
10. Ayuso-Montero R, Mariano-Hernandez Y, Khoury-Ribas L, Rovira-Lastra
B, Willaert E, Martinez-Gomis J. Reliability and validity of T-Scan and 3D
intraoral scanning for measuring the occlusal contact area. J Prosthodont. Corresponding author:
2020;29:19–25. Dr Jordi Martinez-Gomis
11. Kordaß B, Amlang A, Hugger A, Behrendt C, Ruge S. Number and localization Department of Odontostomatology
of occlusal contact areas on natural posterior teeth without dental findings- School of Dentistry
evaluations of the regional baseline study (SHIP-1) with the Greifswald Digital University of Barcelona—Bellvitge Campus
Analyzing System (GEDAS). Int J Comput Dent. 2022;25:47–56. s/n Calle de la Feixa Llarga
12. Wang Q, Zhao Z, Zhou M, et al. In vivo evaluation of the reliability and L′Hospitalet de Llobregat
validity of three digital occlusion analysis methods. J Dent. 2022;127:104355. Barcelona, Catalonia 08907
13. Rovira-Lastra B, Flores-Orozco EI, Ayuso-Montero R, Peraire M, Martinez- SPAIN
Gomis J. Peripheral, functional and postural asymmetries related to the preferred Email: jmartinezgomis@ub.edu.
chewing side in adults with natural dentition. J Oral Rehabil. 2016;43:279–285.
14. Khoury-Ribas L, Ayuso-Montero R, Willaert E, Peraire M, Martinez-Gomis
J. Changes in masticatory laterality 3 months after treatment with unilateral Acknowledgments
implant-supported fixed partial prosthesis. J Oral Rehabil. 2020;47:78–85. The authors thank “Hospital Odontològic Universitat de Barcelona” of the
15. Qadeer S, Özcan M, Edelhoff D, VanPelt H. Accuracy, reliability and clinical “Fundació Josep Finestres” for lending the intraoral scan (RIOS 3Shape; 3Shape)
implications of static compared to quantifiable occlusal indicators. Eur during the study. The authors also thank Michael Maudsley for editing the text.
J Prosthodont Restor Dent. 2021;29:130–141.
16. Bostancıoğlu SE, Toğay A, Tamam E. Comparison of two different digital
CRediT authorship contribution statement
occlusal analysis methods. Clin Oral Investig. 2022;26:2095–2109.
Bernat Rovira-Lastra: Conceptualization, Methodology, Validation,
17. Morsy N, El Kateb M. Accuracy of intraoral scanners for static virtual
Investigation, Writing - original draft, Visualization. Laura Khoury-Ribas:
articulation: A systematic review and meta-analysis of multiple outcomes.
Conceptualization, Methodology, Writing - reviewing and editing. Elan Ignacio
J Prosthet Dent, 2022 Nov 1:S0022-3913(22)00608-4. doi: 10.1016/j.
Flores-Orozco: Conceptualization, Methodology, Writing - reviewing and
prosdent.2022.09.005. Online ahead of print.
editing. Raul Ayuso-Montero: Conceptualization, Methodology, Resources,
18. DeLong R, Ko CC, Anderson GC, Hodges JS, Douglas WH. Comparing
Writing - reviewing and editing, Supervision. Akhilanand Chaurasia:
maximum intercuspal contacts of virtual dental patients and mounted dental
Conceptualization, Methodology, Writing - reviewing and editing. Jordi
casts. J Prosthet Dent. 2002;88:622–630.
Martinez-Gomis: Conceptualization, Methodology, Validation, Investigation,
19. Edher F, Hannam AG, Tobias DL, Wyatt CCL. The accuracy of virtual
Formal analysis, Writing - original draft, visualization, Supervision.
interocclusal registration during intraoral scanning. J Prosthet Dent.
2018;120:904–912.
20. Sigvardsson J, Nilsson S, Ransjö M, Westerlund A. Digital quantification of Copyright © 2024 The Authors. Published by Elsevier Inc. on behalf of the
occlusal contacts: A methodological study. Int J Environ Res Public Health. Editorial Council of The Journal of Prosthetic Dentistry. This is an open access
2021;18:5297. article under the CC BY-NC-ND license (http://creativecommons.org/licenses/
21. Zhao Z, Wang Q, Zheng X, et al. Reliability and validity of two computerised by-nc-nd/4.0/).
occlusion analysis systems. J Dent. 2022;118:104051. https://doi.org/10.1016/j.prosdent.2023.06.036

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