In dentistry, accurate means of recording occlusal contacts is important. It is necessary to understand occlusion and errors produced during recording occlusal contacts. Occlusal interferences of just a few microns can result in myalgia and temporomandibular dysfunction. The aim of any restorative treatment is to establish occlusion that is in harmony with the stomatognathic system. Occlusal indicators are used to locate and define occlusal contacts in prosthetic restorations. Over the years various occlusion testing materials have been used to assess any occlusal interferences. For obtaining a proper occlusion it is important to understand the properties of materials and methods to record occlusal contacts. This review article overviews the various materials and methods that have been used as occlusal indicators.
Key words: Occlusal indicator, occlusal contacts, occlusal interference
The activities of chewing, swallowing and
speaking greatly depends both on intra arch
and inter arch tooth position.1
The occlusal contacts undergo constant changes with every tooth
restoration, extraction and prosthetic care. Conventional concepts of traumatic occlusal interferences involve a single anterior or posterior tooth,
which is the “supracontact” during maximum
intercuspidation or excursive jaw movement. Severe irritation can be triggered by an occlusal
interference of only few microns. The patient will
not bite on the new prosthesis in order to avoid
any unpleasant sensation. The new bite of convenience can be obtained by moving his lower
jaw into a physiologically unsound position that
results in irregular muscle activity. This leads to
temporomandibular joint pain and myalgia. Occlusal indicators are used to locate and define
occlusal contacts.2
Over the years various materials and methods have been used to detect high spots. Occlusal indicators differ not only in
their marking characteristics but also in material properties such as thickness, tensile strength
and plasticity. The aim of occlusal adjustments
is to provide maximal intercuspation of teeth in
centric relation, by removing centric pre-maturities and any eccentric interference.3
It has been
a real challenge for achieving occlusal markings over some restorations such as gold, metal
alloys, ceramics and on moist occlusal surfaces.
For the correct assessment of occlusion in prosthodontic treatment, it is important to understand
the patterns of tooth contact, properties of materials and methods used to record these tooth
contacts.2
Occlusal indicators are classified as qualitative and quantitative indicators.
Qualitative/non-digital/conventional indicators
Quantitative/digital indicators
The location and number of tooth contacts are
determined by qualitative indicators whereas
quantitative indicators determine the time, sequence and force characteristics of tooth contacts.
Articulating paper
Articulating papers are the most commonly used
qualitative indicators. They varies in terms of
thickness, width and the type of the dye impregnated. They consists of a coloring agent and a
bonding agent (transculase) between the two
layers of the film. The coloring agent is expelled
from the film on occlusal contact and the bonding agent binds it on to the tooth surface. The
marking obtained consists of a central area that
is devoid of the colorant and surrounded by a
peripheral rim of the dye. This region is the ‘target’ and it denotes the exact contact point. It is
also called as ‘iris’ because of its appearance.
The density of these markings does not represent
the force of the contact; instead, heavier contact
tends to spread the mark peripheral to the actual location of the occlusal contact. The central
portion in heavy contact areas indicates the interference that needs correction. They should be
used in a dry field as it can be ruined by saliva
easily. They can make pseudocontact markings
because of their relatively inflexible base material.
Bite intensity detecting articulating paper
This was invented and patented by August Kokal
in 1976. It comprises of an upper paper and lower paper or mesh layer and many ink granules
which are interposed between the two. Each ink
granule is surrounded by a membrane with variable thickness that ruptures at different biting
pressures. For example green ink granules have
thin membrane which is designed to be rupturable at biting pressure of 300-500 psi, red ink
granules at 500-700 psi, blue at biting pressure of 700-1000 psi. This articulating paper would
mark the teeth with different colours which gives
the operator a clear picture of the different points
of occlusion with the different biting pressures.4
Articulating silk strips
It is made up of a micronized color pigment,
embedded in a wax-oil emulsion.5
Articulating
silk strips are made from high quality natural
silk. It consists of fibrils which are tube shaped
protein structures and has high colour reservoir
capacity. This silk is highly tear-resistant. It has
soft texture and does not produce any pseudo
markings. It is highly suitable for use on highly
polished surfaces, particularly ceramic and gold
in lab models, where one strip can be used as
many times.4
Gail C Halperin et al. in their review on occlusal
registration strips concluded that the occlusal
registration should be less than 21 µm (micron
meters) and should possess plastic deformation.6
Articulating foil
Articulating foils have a thickness which is
around 8µm and are known to produce more accurate readings than paper and silk. It has less
marking ability under reduced pressure and
glossy surfaces. Hence greater pressure must be
applied for the clinical use of foils.4
The Artifol articulating film (Bausch Inc.) has thickness of just
8µm, which is less than the thickness perception
level of the patient. It must be used in a dry environment with special holders. It is universally
applicable, both on lab models and intraorally.5
They are also manufactured with an additional
emulsifier which gives them bonding properties
on moist occlusal surfaces. This is achieved by
adding special bonding agent transculase, or
wetting agents like lecithin. On occlusal contact,
the colouring agent is expelled from the film and the bonding agent binds it on to the tooth surface.4
Metallic shim stock film
The shim stock film is colour coded on one side
and has a metallic surface on other side. It is
mainly indicated for use in the occlusal splint
therapy in order to accurately mark the contacts
on the soft splint in the laboratory.5
High spot indicator
This is in the liquid form. It is indicated to check
the proximal contacts of crowns, telescopic
crowns, inlays, onlays and clasps. The liquid is
applied on the proximal surface of the coping
and a film with a thickness of 3µm was formed.
The proximal contact area is delineated as an
area of show through in the base material of the
crown when dye is removed.5
Fleximeter strips
Fleximeter strips measures the height of the
preparation. They are made of silicone rubber
which can be sterilized to the temperature of
200°C. They are available in 3 different thickness: 1mm, 1.5 mm and 2 mm. Occlusal indicator paint can be applied onto these strips and
can be used as a marking indicator.4
Gnatho-film
Gnatho-film is a soft and flexible occlusal film. It
was developed by Bausch. It is Ultra thin, 16 µm
polyethylene, with a colour coating of 6 µm, consisting of waxes with hydrophilic components.
This unique film adapts perfectly to the individual conditions of the receptive occlusal surface
and is extremely tear resistant. The flexibility of
polyethylene helps in precise checking of the actual contact points. It is available in various colours like green, blue, red, black and in different
sizes (20x60 mm or 70x100mm).4
Dental floss with a pressure sensitive
material
Interproximal contacts are as important to the
dentist as occlusal or biting contacts, during
seating of crowns and bridges. Articulating floss
impregnated with a pressure sensitive material
may be used to mark tooth contacts interproximally between one tooth and an adjacent tooth.4
Silicon putty material
Silicone putty can be mixed and placed on the
occlusal surface and interocclusal records are
made. They are placed on the casts after trimming. The location of tooth supracontacts can
be identified as perforations in the silicone putty
records. The interocclusal record is then placed
on the occlusal surface of the teeth or cast and a
colour indicator is painted into the perforations
of each record with a fine camel hair brush. This
would produce markings which can be adjusted
to eliminate them.4
The two-phase occlusion indicator
method
In this method, the articulating paper and the
articulating film are used sequentially. The articulating paper mark the contacts consisting of
a clear central region which is surrounded by a
peripheral rim of the dye. The articulating foil of
a contrasting colour is used to mark the center of
the contact areas highlighted by the articulating
paper markings initially. The actual interferences are the central areas and are to be eliminated.4
Transparent Acetate Sheet
It was described by Davies et al. in 2005. It
makes use of an occlusal sketch technique as a
means of recording occlusal contacts. The occlusal sketch consist of a transparent acetate sheet
that represents the occlusal aspects of the teeth.
The use of acetate helps to assess the marked occlusal contacts from both sides. The dynamic and static occlusal contacts were marked. To
identify the locations of occlusal contacts, after
completing the occlusal record for each subject,
the contact anatomic regions were traced onto
each occlusal sketch. The occlusal sketches
were overlaid by a 1-mm two transparent grid to
enable comparison between the 3 clinicians by
comparing the x and y coordinates for each occlusal contact in a specific region. The occlusal
sketch is a simple way of recording the occlusion
of patients. Furthermore, this technique is quick,
inexpensive, and easy to perform.7
Occlusal Sprays
It is a universal color indicator to test the occlusal contacts and accurate fit of crowns and
bridges. It is easy to handle (Bausch Arti-Spray
Occlusion-Spray) and leaves a thin colored film
which can easily be removed with water, leaving
no trace of residues. It is applied at a distance
of 3-5 cm onto the occlusal surface or inside the
crown or bridge. When testing occlusion or trial
seating the bridge or crown, all contact points
will be immediately visible. It can be used for
adjusting proximal contacts when trial seating
crowns and bridges.3
Photo occlusion
A thin photoplastic film layer/ memory wafer is
placed on the occlusal surface and the patient
is asked to occlude on the wafer for 10 to 20 seconds. It is inspected under a polariscope light.
The location and intensity of occlusal contacts
are verified and the results are then transferred
to a graphic occlusal scheme. Light contact is
seen as yellow, orange or red colour and shows
40% of light penetration where as in medium
contact the percentage of penetration is 40-48%
and the colour patterns are blue centered within
the light coloured pattern. In heavy contact the color pattern is orange and yellow at the center
and has 48 to 60% of penetration. E. Gazit et al.
studied the reproducibility of the Novel photo
occlusion (NPT) and color marking technique
(CMT) by comparing two consecutive occlusal
records and records made at l-month intervals
and concluded that the NPT is more reproducible than the CMT.8
T-Scan
The T-Scan occlusal analysis system (Tekscan)
is a Microsoft compliant system that can record
a given contact sequence in 0.01-s increments.
It consists of a piezoelectric foil sensor, a sensor handle, both hardware and software for processing the data. The T-Scan assess the time
magnitude and the distribution of the occlusal
contacts. The T-Scan system digitally record the
timing and location of tooth contacts. The tooth
contact information is represented as moments
of time in the sagittal axis and transverse axis of
the occlusal plane. Time moments are defined
as the sum of distances of the tooth contacts in
millimeters from the ‘x’ or ‘z’ axis of the occlusal
plane multiplied by their relative time value (1-
sec) and divided by the sum of the onset times.
The manufacturer purports that, when the time
moments in these axes are analyzed, an occlusion can be uniquely described. The advantage
of this instrument over silk marking ribbon is that
it records contacts and helps to analyze the timing and force of each contact.5
Occlusense
Occlusense is a new digital occlusion product
that was introduced in 2019. It is a wireless digital system handle and sensor that transmits the
data to an iPad Application via a Wi-Fi connection. The patient’s recordings are displayed on
the App.9
It has a sensor with built-in articulating paper that marks the occlusal contacts on
the teeth.10
Virtual Dental Patient (2002)
Virtual technologies in dentistry are used to provide better education and training by simulating
complex contexts and enhancing procedures that
are traditionally limited, such as work with mechanical articulator. This is a recently introduced
concept where the casts of a patient’s dentition is
scanned to obtain the data of three-dimensional dental patient This provides quantitative information to analyse the chewing function and
interferences in occlusion. The aligned virtual
casts helps to calculate occlusal contacts.5
Different occlusal registration materials have
been used for recording the occlusal contacts
since years. The occlusal indicator should have
some amount of plastic deformation before it
tears or before any deformation occurs. The articulating papers, foils, silk strips, and T-Scan
system were associated with different rates of
decrease in contact numbers on multiple uses.
The repeated use of the sensors negatively affects the success of the T-Scan system. Occlusal
contact numbers increased greatly when the
teeth were dry. Every material has both advantages and limitations. The choice of occlusal
indicators depends upon the clinical situation,
clinician’s choice and expertise, economics and
comfort.