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The role of resin modified glass ionomers in restorative dentistry.
By Dr. Ara Nazarian
Today, restorative dentistry emphasizes minimally invasive approaches.
This encompasses prevention, remineralization, and when needed, adhesive
restorations. These approaches lessen the chance for subsequent adverse
outcomes, including advancement of tooth decay, pulpal involvement
and tooth fracture.
As dentists, our goal is to have the knowledge of various dental
products to select the best material for any given scenario. In cases
where isolation may be a problem resulting in moisture contamination
or where there is a high caries rate because of medications, diet,
or age, I personally have found the use of resin modified glass
ionomer restorations very useful. Some indications for use include
the following: small Class I, II, and III restorations; Class V
restorations; deciduous teeth restorations; geriatric restorations;
pit and fissure sealants; core build-ups; root surface restorations;
cervical erosion; and abfraction lesions.
A patient presented to our office for her six-month dental hygiene
appointment where we performed her periodic oral examination. During
this examination, we identified that a resin sealant on tooth No. 14
—placed many years prior—was breaking down and there was some staining
and incipient decay present on the occlusal surfaces of teeth
Nos. 13 and 15. Capturing an image of these teeth on the intraoral
camera (RF Systems Lab), we indicated the areas of concern on the
flat screen monitor (Fig. 1). Using the DemoDent (DemoDent Inc.)
patient education model, we described what was occurring in the
tooth (Fig. 2).
There are three layers in a tooth, as illustrated by the model in
Figure 3. The white is the enamel, the yellow is the dentin, and the
pink is the nerve. We explained to the patient that her cavity is in
the biting surface of the tooth, where food and debris like to collect.
When the cavity is in the enamel (white layer) she would not usually
have any pain or sensitivity with it. We told her that by catching
the cavity early, we can clean it out without the need for anesthetic
in most cases. Once the cavity has gone through the enamel and into
the dentin (yellow layer), it spreads much more quickly. Patients may
experience some sensitivity to hot, cold, and sweets, depending upon
how deep it has extended. Once the cavity gets into the nerve
(pink layer), patients experience constant throbbing pain.
We emphasized that we want to prevent this by stopping the cavity
as soon as possible. After explaining the situation using the image
on the screen and the anatomical model, I found that the patient
better understood her dental condition and was eager to get started.
Once the patient agreed to treatment, she was scheduled for the
restorative part of the procedure. All risks, benefits, and
alternatives regarding the use of a resin modified glass ionomer
were discussed with the patient. We chose to use Riva Light Cure (SDI),
a combination of glass ionomer and composite resin. These fillings
are a mixture of glass, an organic acid, and resin polymer that hardens
when light cured. The light activates a catalyst in the restoration
that causes it to cure in seconds. This combination of a glass ionomer
and resin has excellent esthetics, high fluoride release and chemically
bonds to the tooth structure.
In fact, it has free movement of fluoride, which provides benefits to
surrounding and adjacent tooth surfaces. Fluoride is held within the
glass ionomer matrix without being bound by the structure. If the level
outside the glass matrix is lower, then fluoride ions are released.
Conversely, if the fluoride level is higher (e.g., topical fluoride)
then fluoride will recharge the glass ionomer matrix. Also, they are
not subject to shrinkage and microleakage, as the bonding mechanism
is an acid-base reaction and not a polymerization reaction.
Using micro-preparation burs (Komet), the old resin restoration and any
decay was removed from tooth No. 14 as well as any staining or decay
from teeth Nos. 13 and 15 (Fig. 4). Riva Conditioner (SDI) was applied
to the teeth for 10 seconds and then washed thoroughly. Any excess
water was removed, taking care not to desiccate the tooth, but in fact
keep it slightly moist. The Riva Light Cure RMGI (SDI) capsule was
activated and placed in an amalgamator for 10 seconds. Once activated,
the capsule was loaded in the dispensing gun and placed into the
reparations (Fig. 5).
Final set was achieved after light curing for 20 seconds using the Radii
Plus (SDI). After light curing, we finished the restorations under water
spray, using Q-Finisher burs (Komet). As seen in the postoperative image
(Fig. 6), the combination of glass ionomer and resin in this new class of
material yielded an esthetic and functional restoration that has high
fluoride release and bonds to the tooth structure.
After many decades of improvements in oral health, tooth decay is on the
rise again. Much of the blame can be placed on today’s diet consisting of
fast food, soda pop, sport juice, and energy drinks. Another factor that
comes to mind is aging Baby Boomers who are living longer. A majority of
these patients may be taking medications that are causing severe dry mouth
(xerostomia) that results in a high caries rate; or they simply are unable
to brush and floss properly because of hand dexterity issues. Hence, resin
modified glass ionomer restorations can be used as a treatment modality
for patients who are at high risk for caries. Whatever the situation,
it is important for all dentists to recognize proper selection of dental
materials for particular situations.
Ara Nazarian, DDS
is a graduate of the University of Detroit-Mercy School of Dentistry.
Upon graduation, he completed an AEGD residency in San Diego with the
U.S. Navy. He is a recipient of the Excellence in Dentistry Scholarship
and Award. Currently, he maintains a private practice in Troy, Mich.,
with an emphasis on comprehensive and restorative care. He has conducted
lectures and hands-on workshops on esthetic materials and techniques
nationally and internationally. Dr. Nazarian also is the creator of
the DemoDent patient education model system.