New Mexico Dental Journal Spring 2015

New Mexico Dental Journal, Spring 2015

Aesthetic failures due to

poor emergency profile/

wrong abutment choice

We have all seen “lollipop-on-a-stick”

implant restorations. They not only

look awful, but they often create black

triangles that trap food and plaque and

can often lead to other dental problems.

Preparing the gingiva prior to final

impression provides proper contour and

support for the final prosthesis and helps

avoid this problem.

This preparation starts first with the

proper transmucosal healing abut-

ment. Rarely should the skinniest be

used. Rather, as a rule of thumb, use

the widest healing abutment available,

especially in the posterior. This can

save several weeks and several appoint-

ments. At times it may be necessary to

make a custom healing abutment to

start shaping the emergence profile.

Further contouring can then be achieved

through use of a screw retained tempo-

rary. Several appointments spaced out

over several weeks may be necessary to

add or subtract from the abutment until

proper shape and contour is achieved

(See Figure 7).

Prefabricated abutments are conve-

n ient and qu ick , but l imit t he

shape and contour t hat c an be

achieved. Custom abutment s (See

Figures 8) have become readily avail-

able and inexpensive (somet imes

even cheaper) depending on the material

chosen (Titanium, Zirconia, or Gold).

They provide the ability to precisely

match the gingival contour that took

weeks or even months to achieve. They

also allow the crown margin to be placed

right at the gingival margin which facili-

tates proper removal of excess cement.

While cast UCLA gold abutments have

been around for many years, titanium

and zirconia have virtually replaced

their expensive and labor-intensive

predecessor. However, when selecting an

abutment, be sure to take into account

the size of the final restoration and the

forces it will receive. Also consider the

esthetic limitations of each. For example,

titanium abutments, while very strong,

can cause a gray hue to appear through

the overlying gingiva. In a patient with

thin gingiva in the esthetic zone, perhaps

a colored abutment or a zirconia abut-

ment may be indicated.

Zirconia abutments offer many esthetic

qualities we seek in obtaining an invis-

ible restoration, but they are more brittle

and not as modifiable after fabrication

and sintering. Microcracks are invari-

ably introduced when the abutment is

adjusted by a bur, even with high speed

and water. These can lead to fracture of

the abutment under load.

When choosing an abutment, consider

the following:

size of the implant

(narrow

vs. regular vs. wide diameter),

size of

the edentulous space

(incisor vs. molar,

short vs. tall),

type of final restoration

(PFM, Lithium DiSilicate, Zirconia), and

esthetic demands

(high smile line, thin

vs. thick biotype). While there are manu-

facture specs that should be followed for

strength of the abutments, one needs

to also rely on clinical judgment and

experience to choose the appropriate

abutment.

A word of caution: not all custom abut-

ments are equal. Precise fit of both the

abutment and the screw are of extreme

importance. Quality proprietary implant

components often have the best fit.

Using another company’s restorative

parts can void a manufacturer’s warranty

and even lead to a hardware failure. If

you are going to use a custom abutment

manufactured by another implant

company, I would suggest you research

it well and select a company whose

standards and specs are very high and

will remain high for many years to come.

Hardware failure—

Loose screws,

broken screws,

broken abutments,

broken implants

When dealing with implants, it is impor-

tant to remember that hardware compli-

cations occur 3–4 times more often than

biological complications (Pjetursson et

al. 2014, 2012, 2004; Jung et al. 2008;

Aglietta et al. 2009). So even when all

the circumstances around implant place-

ment are ideal, there remain more factors

that can lead to failures.

Fig 7

—Proper emergence profile created

through the use of a screw retained provi-

sional. Note the support created for the

interdental papilla.

Fig 8

—Milled custom titanium abutment

directly from the manufacturer (Nobel

Biocare)

continues



Five Common Implant Complications,

continued