Dental Asia November/December 2022

USER REPORT
of the large cavity underneath the
metal inlay. Partial pulpotomy was
also performed using MTA cement
(Figs. 3-6).
Fig. 3
Fig. 4
At first glance, the restoration appears
to be typical of Class 2. But if you look
carefully, there is a nodule — a rare
mandibular first molar morphology
— on the centro-lateral side. Called
the “sixth cusp” in Japan, the nodule
occurs in 10-20% of mandibular first
molars.
Fig. 5
Fig. 6
When I treated this tooth, I determined
from preoperative observation of
the crown morphology that there
was originally a sixth cusp. This is
because the crown is wider toward the
centro-lingual side, and the centrolingual
occlusal head would have been
abnormally large if I had tried to create
the usual type of crown (Figs. 7-9).
Figs. 7a-c
If the sixth cusp was not restored,
the outcome would probably be
unacceptable. Hence, whether or not
the surgeon knows that a sixth cusp
can exist in this area can make all the
difference in the result.
Fig. 8 Fig. 9
Fig. 3: Pre-treatment condition: The
mandibular first molar with metal inlay
showing marginal leakage. There are no
spontaneous symptoms, but stimulated by
cold stimulator
Fig. 4: The old restoration was removed and
the tooth was isolated with rubber dam.
Large cavity was observed underneath the
metal inlay
Fig. 5: After removing the decay, a part of
the dental pulp was exposed. It was free
of abnormal finding in the preoperative
diagnosis with microscope. It was decided to
perform partial pulpotomy using MTA cement
Fig. 6: Completion of the partial pulpotomy
procedure and the removal of the
remaining infected dentin and beveling.
In this phase, I make the prediction of the
final morphology
Figs. 7a-c: If we simply think of the
mandibular first molars as five cusps and
place them in textbook form, the final
restorations would appear too large as
shown in Figs. 7a-b.
Fig. 8: Post operative condition: As shown
in Fig. 7c, the restoration settled into a
morphologically comfortable arrangement
Fig. 9: Post-treatment one year later
ABOUT THE AUTHOR
Dr Nokame Yoshinori graduated from Nihon University
School of Dentistry in Matsudo, Japan, in 2010. Since 2011,
he has served as the deputy director of Nokame Dental
Clinic. He is board certified by the Japanese Association of
Microscopic Dentistry (JAMD) and The Academy of Clinical
Dentistry.
CONCLUSION
Knowing the textbook morphology
of teeth is important, but merely
memorising them will not
automatically lead to aesthetic
results, as not all teeth have the same
shape. The teacher to learn from is
the natural teeth, and observation
teaches us that there are many
variations. That is the fun of direct
restorations. DA
DENTAL ASIA NOVEMBER/ DECEMBER 2022 43