1. Tips from the lab
Predictable impressioning
EQUIPMENT
By John C. Cranham, DDS, Chesapeake, Va.
② Control the soft tissue through preliminary
W
ithin a well-run den- dictability to all indirect esthet- employed to consistently place the
tal practice, a direct ic/restorative dental procedures. margin one-half the depth of the mouth preparation and chemotherapeutics
relationship exists healthy pocket. If the pocket is 2.5 Starting with a healthy mouth is a
between pre- Soft-tissue management mm deep, then the margin should prerequisite of any restorative pro-
dictability and positive trends. From time to time, it is necessary be placed 1.2 mm underneath the cedure. Proper preliminary
These benefits include increased to control a minor amount of gin- tissue. This will create an invisible mouth preparation should
production, decreased overhead, gival bleeding during a restorative margin, and one that exists in a include any and all procedures to
M AT E R I A L S
increased profitability, decreased procedure. Inadvertently nicking healthy relationship within the get the mouth completely free of
stress, and increased happiness of the tissues during margin refine- periodontal structures. disease prior to the final restora-
the entire dental team. The better ment does occur occasionally and tive phase. Healthy tissue will
we become at doing procedures it is essential to have the ability to Retraction options make our job easier and the final
correct the first time, the more we quickly control hemostasis. There are many excellent ways to esthetic/restorative result more
can experience the attributes pre- Viscostat from Ultradent dis- retract tissue if the only goal is to predictable.
viously mentioned. Becoming pre- pensed from its Dental Infusor is a simply expose the gingival margin. Additionally, chemotherapeutic
dictable in our work should be the fast, predictable way to obtain 100 Laser troughing and electrosurgi- agents such as Viscostat (Ultradent
primary focus of every dental percent control. cal procedures are both excellent Products, figure 2, below) can be
A S S I S TA N T S
practice. Without predictability, ways to expose the restorative mar-
there is great uncertainty, and Start with an impressable preparation gins. A retraction cord, while more
found within uncertainty is a high Most restorative dentists do not time-consuming, can be used to
degree of stress. trim their own dies. While many more predictably place the margin
For a dental practice that does teaching institutions recommend in the ideal zone within the gingi-
any amount of indirect restorative doing this, with consistently excel- val sulcus.
dentistry, learning a tried-and-true lent impressions, it is actually an A two-cord technique has been
technique that consistently cap- unnecessary step. It is important, described to accomplish this goal.
tures the necessary details of an therefore, for dentists to prepare The technique described in this
impression is a vital component. teeth in a way that their margins article is a modification of this
Yet, after speaking to hundreds of are easily identifiable. We should process utilizing contemporary
FOCUS
laboratory owners over the last sev- learn to prepare teeth with a con- materials.
eral years, it is obvious that consis- sistent margin design 360 degrees used by directly applying it to the
tently excellent impressions are a around the tooth. If a contempo- A step-by-step approach to an tissue to stop any localized bleed-
rarity. rary metal ceramic material is your ideal final impression ing. This can also be used to soak
restorative choice, then a chamfer ① Start with an impressable preparation the retraction cords (figure 3,
Start with healthy tissue margin with the same general look below). This chemical agent
It is important to understand that, should be utilized. If you prefer
in fabricating an indirect restora- more of a knife-edge or even a
tion, the purpose of the impres- shoulder, the key is to develop a
sion is not to simply capture the preparation style that your dental
details of the hard tissues. The laboratory gets used to seeing. You
goal is to also capture the stable want to avoid having a margin that
relationship of the gingival tissues. starts as a chamfer, then turns into
If we do indirect restorative proce- a knife-edge, and then ends in a
dures in the presence of gingival shoulder. These become very diffi- In figure 1 (above), you will see a
inflammation, the final restorative cult to read and trim. Preparing tooth prepared for a Captek
result will likely be inadequate, no teeth with consistent margin Crown. The preparation has ade-
matter how “good” the impres- design will add tremendous pre- quate reduction (as described in (Ferric Sulfate), not only rapidly
sion. After final crown placement, dictability in the laboratory repro- Part 1 of this series, printed in achieves hemostasis, but also fixes
when the gingival tissues return to duction of your preparations. January) and has been smoothed the tissue, holding it in the retract-
normal size, shape, and contour, and polished. The margin design ed position for a longer period of
exposure of a margin will occur. Consistent margin placement is that of a chamfer, around the time. This material is an important
While the crown may fit fine, the Consistent margin placement is entire circumference of the tooth. component of any restorative den-
outcome is likely to be below the key to providing a restoration that Employing this type of prepara- tist’s armamentarium.
patient’s esthetic expectations. will meet the esthetic goals of the tion guideline will dramatically
Beginning with healthy tissues patient and the optimum health of increase the readability of your ③ Placement of first cord
will also simplify the impression- the restorative result. Not prepar- impressions since your laboratory Prior to final margin placement,
making process. Bleeding tissues ing far enough into the gingival support will know exactly what it is the first cord should be packed. A
can be controlled, but should not sulcus will lead to esthetic prob- looking for. Whatever margin 00 Ultradent cord that has been
be “the norm.” Taking patients lems, while going too deep will design you personally prefer, keep- soaked in Viscostat is placed into
through proper periodontal pro- invade the biologic width. ing it consistent will increase the the depth of the sulcus (figure 4).
cedures and completing all neces- By beginning with healthy tis- quality and predictability of the As shown in figure 5, the goal is to
sary preliminary mouth prepara- sue and using normal probing final restorative result. have it perfectly fit once around
tion will add tremendous pre- depths, a technique can be
46 Dental Equipment & Materials • May/June 2003

2. Comprecap, pushing the Expasyl way into an otherwise perfect
further into the pocket (figure impression.
EQUIPMENT
12). This provides additional
retraction by forcing the tissue fur- ⑨ Visually inspect impression
ther away from the tooth. When The final step is visual inspection
you combine this benefit with the of the impression. Loupes or some
additional hemostatic and drying sort of magnification should be
gival sulcus (figure 8, above). It properties of this material, used to check the details of the
Figure 4 (above), Figure 5 (below) master impression. As previously
has hemostatic agents within its Comprecap makes for a very pre-
body and also has the ability to dictable method for margin cap- mentioned, all margins should be
absorb crevicular fluid. The most ture. visible with a minimum of .5 mm
positive clinical effect observed is apical to the marginal tissues (fig-
M AT E R I A L S
not just great retraction, but a very ⑦ Visually inspect retraction objectives ure 15).
dry field. In fact, there seems to be After washing away the Expasyl By combining all of the ele-
a complete absence of fluid (simply remove by spraying with a ments of healthy tissue, correct
around the preparation — a quali- three-way syringe) and removing preparation design, predictable
ty that makes for an ideal impres- the retraction cord, visual inspec- retraction, and highly esthetic
the tooth. Pressure should be sion. tion is the final step before taking porcelain contour and color, we
applied so that the 00 cord is sit- the impression. This is when the can all achieve excellent clinical
ting at the base of the healthy ⑥ Apply pressure with Comprecap doctor should put on his or her results. The outcome can be seen
pocket. After dispensing the appropriate loupes and, using excellent light- in this delivered IPS d.SIGN
A S S I S TA N T S
amount of Expasyl over the retrac- ing, visually inspect the retracted Porcelain to Captek restoration
④ Margin refinement tion cord (figure 9) circumferen- tissue (figure 13, below). All mar- (figures 16 and 17).
Once the tissue has been retracted Indirect restorative procedures
with the first cord, the margin is can be a highly predictable, highly
finished by dropping the margin profitable component of any den-
to the top of the cord (figure 6, tal practice. To achieve this, how-
below). The placement of the cord ever, the dental team must employ
some simple, disciplined steps to
achieve consistent results. This
article has outlined a step-by-step,
Figure 9 (above), Figure 10 (below) highly predictable method of
FOCUS
gins should be easily viewable with obtaining an ideal final impres-
a minimum of .5 mm of additional sion.
tooth structure apical to the mar- Acknowledgment: The author
gin. Figure 13 exhibits the ideal would like to thank the technical staff
will protect the biologic width and retraction goals. of Dental Arts Laboratories, Inc. in
prevent us from going too far into Peoria, Ill., for their excellent ceramic
the pocket. This is where this tech- ⑧ Inject with quality impression material artistry in preparation of this case.
nique may have an advantage over A polyvinyl impression material Call (800) 227-4142 to contact DAL.
laser or electrosurgical retraction. tially around the tooth, a such as Take One from Kerr can Note: For complete information on
While other techniques can rapid- Comprecap (figure 10) is placed be utilized to complete the impres- Cranham Dental Seminars, visit
ly attain exposure of the restora- over the prepared tooth. sion procedure. While this materi- www.cranhamdentalseminars.com or
tive margin, there is greater risk of Comprecap, made by Roeko, look al has hydrophilic properties, contact Dr. John Cranham’s office at
invading the biologic width or like a hollowed-out cotton roll, but every effort should be made to (757) 465-8900.
leaving the postoperative margin are open only on one side and are keep the field dry. Dry angles, cot-
visible. firmer (figure 11). Once placed ton rolls, and suction should be
employed to keep saliva out of the
⑤ Addition of contemporary retraction material field. This is particularly impor-
A very popular method of obtain- tant in the mandibular area. When
ing ideal retraction involves the injecting (figure 14, below), keep
placement of two cords on top of
one another within the pocket.
This technique follows a similar
path, but uses a contemporary
dental material called Expasyl (fig- Figure 11 (above), Figure 12 (below)
ure 7, below), recently introduced
the tip angled at the margin and
burnish the material around the
tooth. The thixatropic nature of
by Kerr. This material has a clay- this material will allow it to flow
like consistency that is released over the prepared tooth, the upon itself, eliminating voids, bub-
(under pressure) around the gin- patient can bite on the bles, and fins that can find their
From top to bottom, Figures 15-17
48 Dental Equipment & Materials • May/June 2003