Esthetics of Artificial Gingiva

20THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Correspondence to: Dr Marie-Violaine Berteretche

Faculté de Chirurgie Dentaire, 5 Rue Garancière, 75006 Paris, France.

Fax: 00 33 1 57 27 87 01. Email: [email protected]

The Esthetics of Artificial Gingiva

and Complete Dentures

Marie-Violaine Berteretche, DDS, PhD

Assistant Professor, Department of Prosthodontics, Faculty of Dentistry,

Denis Diderot University, Hôtel-Dieu Garancière Dental Hospital, Paris, France.

Olivier Hüe, DDS, PhD

Professor, Department of Prosthodontics, Faculty of Dentistry,

Aix-Marseille University, La Timone Hospital, Marseille, France.

Patients’ esthetic demands are increasing daily and now extend to

the artificial gingiva of removable dentures. This article proposes a

systematic approach to analyze and reproduce the gingival char-

acteristics. This three-step process involves the gingival display of

the smile line, gingival pigmentation, and gingival morphology. Dif-

ferent procedures using either polymethyl methacrylate resins and/

or composite resins can be used to reproduce the gingival features.

These innovative techniques make it possible to produce highly es-

thetic complete dentures for edentulous patients presenting with a

“gummy” smile, and the results offer satisfactory long-term stability.

(Am J Esthet Dent 2012;2:20–31.)

© 2012 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.

The need for highly esthetic restorations has become an increasing

trend in contemporary odontology.1 The facial appearance, smile,

and teeth all play a role in dental esthetics and in defining and asserting

an individual’s personality.2 The face plays a key role in the psychol-

ogy of self-identification and self-presentation. An individual will always

scrutinize the face, lips, and teeth of his or her partner in conversation.

Research shows that a good dental appearance is required in many

social groupings.3 Consequently, facial attractiveness is closely tied to

the presence of an ideal smile as defined by prevailing criteria in west-

ern culture.4 A major esthetic factor in western society is the pressure

to look younger.

Recently, researchers have established a set of criteria to define the

principles governing the ideal smile in a dentate patient, regardless of

age.5,6 These criteria concern the following factors:

• The face: reference lines, planes of symmetry, profile, facial propor-

tions7

• The tooth-to-lip ratio: lip movement, tooth visibility at rest, curve of

the incisal edges and lower lip8,9

• The tooth: form, dimensions, color, surface texture10

• The marginal gingiva: collar form and position, form of the gingival

papillae11,12

21VOLUME2•NUMBER1•SPRING2012


BERTERETCHE AND HüE


The technical-therapeutic approach-

es employed in fixed prosthetics have

focused on matching and reproducing

these criteria with or without input from

implant dentistry. While patient objec-

tives concerning removable complete

or partial dentures with or without im-

plants have always focused on restor-

ing dental function, there has been a

shift toward esthetics as a major patient

requirement in prosthetic success.

However, restoring esthetics often

proves incompatible with restoring func-

tional stability in the oral environment.

Stability hinges on a single straightfor-

ward principle: mounting teeth on the

ridge, which equates to ignoring a lack

of support for the cheeks and lips.13

This remains a respected principle and

has ultimately created the “denture

look.” However, the rule championed by

Earl Pound in 1954 established that “the

teeth will be set up back in the origi-

nal position from which they came.”14

Various esthetic concepts have been

grafted onto this core rule, including the

dentogenic concept,15 golden or divine

proportion,16,17 and visual perception.18

These appearance-based criteria for

artificial teeth combined with the dental

materials used create an arsenal that

enables dentists to meet patients’ es-

thetics expectations. The vast majority

of dental patients are extremely con-

cerned about the appearance of their

future prosthesis and will idealize their

prior smile and dentition. Most patients

express a need for well-aligned white

teeth and a concern about the percep-

tion others will have of their prosthesis.

Dental practitioners need to define

their patient’s esthetic conceptions. To

achieve this goal, they must account

for criteria spanning from cultural es-

thetics19 to psychologic issues20 and

should involve the patient in the pro-

cess21 to perfectly align the dentist’s

design with the patient’s perception.22

Recently, gingival display has been

increasingly recognized as an esthetic

factor in both natural dentition and re-

movable dentures. In natural dentition

with fixed partial dentures, thickness

and gingival pigmentation are ignored

since they are patient-acquired and

patient-specific. For removable den-

tures, however, reproducing these dif-

ferent characteristics is essential for

restoring oral esthetics.

Achieving proper gingival esthetics

depends on three key factors: analy-

sis of gum features, the materials em-

ployed, and technical outcomes. The

purpose of this article is to provide a

systematic approach to the analysis

and reproduction of gingival charac-

teristics in complete denture wearers.

ANALYSIS OF GINGIVAL CHARACTERISTICS

Gingival display

A hidden gingival margin was long

considered the ideal clinical outcome.

Currently, however, it is considered

esthetically acceptable to show 2 to

3 mm of gingival display, although any-

thing more remains unesthetic.4 Some

authors add that permanent visibility

of the posterior teeth and gingival tis-

sue is esthetically desirable. In dentate

patients, the gingival display depends




on the smile line. A low smile line re-

veals only the incisal edges, a midline

smile line displays the teeth, and a high

smile line involves gingival display. In

young dentate patients, gingival dis-

play can extend to the premolar teeth

(45% of cases), especially in women.

Gingival display then decreases sig-

nificantly with age.9 Gingival display is

also directly correlated with ethnicity,

proving extensive in African Americans

but virtually nonexistent in Asian popu-

lations.3,4 This is tied to lip type.8 The

amplitude of upper lip elevation and its

esthetic role are comparable between

completely edentulous and dentate pa-

tients. Through a clinical dental exami-

nation, the dental technician can gain

a clearer picture of the degree of labial

involvement using a labiometer such

as the Papillameter (Candulor USA)

(Figs 1a and 1b).

Fig 1b Labial analysis: (a) lip position at rest; (b) lip position when smiling; (c) assessment of labial

involvement.

Fig 1a The Papillameter (Candulor USA).

a

c

b




If the amplitude of lip elevation is like-

ly to display the future artificial gingiva,

the dental practitioner can choose one

of two approaches: mounting longer

prosthetic teeth or cosmetically stain-

ing the artificial gingiva.

Pigmentation characteristics

In 1960, Dummet23 described gingival

tissue characteristics in the following

terms:

“The color of healthy gingivae varies from a pale pink to a bluish purple. Between these limits of normalcy are a large number of colors which depend primarily upon the intensi-ty of melanogenesis, the degree of epithelial cornification, the depth of epithelization, and the arrangement of gingival vascularity. Moreover, color variations may be uniform, uni-lateral, bilateral, mottled, macular, or blotched, and may involve the gingival papillae alone or extend throughout the gingivae and into other oral tissues. Non-pigmented gingivae are found more often in fair-skinned individuals, while pig-mented gingivae are usually seen in dark-skinned persons.”

In Caucasians, healthy gingivae

show slight variations around pink-

shaded tones. Black patients show

identical gingivae shading to Cauca-

sians but with higher chroma and less

brightness. They also present with dark

brown pigmentation zones of various

intensities; these are caused by me-

lanocytes in the attached gingival layer

of the stratified squamous epithelium,

whereas the layer of free mucosa is

pigment-free.24,25

Morphologic characteristics

Gingival morphology depends not only

on tooth contour but also on sex. In 40%

of cases, the attached gingiva presents

with stippling on the surface, termed

an “orange peel appearance,” which is

synonymous with square-set teeth and

thick, pale gingival mucosa. This sur-

face stippling is found in approximately

two-thirds of men.26 Smoother-grained

gingivae are more common in female

patients with slender teeth, a narrow

zone of keratinized tissue, and a highly

scalloped gingival margin.

MATERIALS

Shading on the artificial gums is repro-

duced using two materials: polymethyl

methacrylate (PMMA) resin, commonly

called acrylic resin, and composite

resin.

PMMA resin

PMMA resins are divided into two

groups: base powders and staining

powders.

PMMA powders developed for build-

ing denture bases are generally pink-

colored, varying from pale to deep

pink according to the brand. They

are available in uniformly shaded or

vein-streaked types with differing de-

grees of translucency. However, these

color tones and textures only partially




re-create the gingival shading.27 Fur-

ther, most of these materials are primar-

ily designed to reproduce the gingivae

of Caucasian patients.

The PMMA powders developed for

staining prosthetic bases present a

broad spectrum of color tones, ranging

from white to various pinks to black (eg,

Aesthetic Color Set Easy, Candulor USA;

Enigma, Schottlander; Kayon Denture

Tinting Stain Kit, Kay-See Dental Manu-

facturing) (Fig 2). These powders can

be blended directly with the denture

base resin or spot-placed while pack-

ing the denture and then processed.

Composite resins

Recent research has led to the devel-

opment of light-curing microfilled com-

posite resins such as Gradia Gum (GC

America) and Amaris Gingiva (VOCO).

After polymerization of the denture

base, the composite is applied to the

resin and then light cured at the lab in

a dedicated chamber without tempera-

ture ramp-up. These composite resins

come in numerous shades and with dif-

ferent flow properties (Fig 3).

Figs 2a and 2b Staining powder set: (a) Enigma (Schottlander); (b) Aesthetic Color Set Easy (Candulor

USA).

Fig 3 Gradia Gum (GC America) composite

resin–based staining syringe set.

a b




TECHNIQUES

Gingival tissue color tones

The color of the denture base is first

determined by translating the gingi-

val shading using the manufacturer’s

shade guide or the laboratory’s home-

made shade guide.28 Then, the pig-

mentation characteristics, texture, and

anatomy of the gingival mucosa are

meticulously mapped. This mapping

sequence is critical. The dental tech-

nician should master the art of recog-

nizing and translating mucosal and

gingival coloring patterns.29,30 When

constructing a single-arch denture, the

gingival characteristics of the natural

arch serve as a reference for the mu-

cosal tissues. The dental surgeon can

provide the lab with important informa-

tion using a series of visual aids, includ-

ing gingival shade guides together with

topographic record bases and photo-

graphs, preferably taken with a map-

ping template.

General color adjustment of the base shade

The overall color of the denture base

is adjusted by directly mixing colored

pigment into the PMMA powder or into

the monomer itself. The powder-fluid

mixture is prepared and then placed

in the flask for curing. In the laboratory,

the principal difficulty is establishing

the ideal base powder-to-pigment ra-

tio. The lab should have professional-

grade custom shade tabs prepared,

with expert-defined base powder-to-

pigment ratios.

Spot color adjustments

There are three technical approaches

for performing localized staining. One

is carried out before the cure cycle,

whereas the other two are carried out

after curing.

Precure staining

The trial denture is flasked, ensuring

that the labial flange is coated with sili-

cone lab putty to preserve the waxing

and finishing of the polished surfaces

of the denture and to reduce polish-

ing time (eg, Flexistone Plus, Ettinger;

Zeta Labor, Zhermack). Once the flask

is opened and a tinfoil substitute is

fitted in place, the spot-staining step

can begin (Figs 4a to 4d). The selected

color-toned mixtures are carefully spot-

ted drop-by-drop onto the selected lo-

cations according to the information

delivered to the lab.

However, as noted by Pound, “The

most difficult part of this technique is

that the colors are placed in the flask

in a reverse manner and the finished

result cannot be seen until the case is

processed.”14 The technical difficulty

involved in this reverse-manner color

placement is compounded by the

placement of the base resin. Injection

techniques cause little or no change in

stratification; this stands in contrast with

pressure-molding techniques, which

are liable to cause shifts in the color-

staining resins. Furthermore, the suc-

cess of this technique depends on the

laboratory’s ability to deliver a perfect

finish on the trial dentures before flask-

ing so as to preclude any risk of partial

tinting damage during the successive




Figs 4a to 4d Spot color adjustments, pre-

cure staining: (a) Preparation of color-pigmented

powder mixtures and heat-curing fluid; (b) inner

surface of the flask at the necks of the teeth

(Flexistone blue [Detax] is visible); (c) applying

colored resin spots at the necks of the teeth;

(d) final result of reverse staining.

a

cb

d




finishing phases. The advantage, how-

ever, is that the final result has excel-

lent long-term stability (Fig 4d).

Postcure staining

The artificial gums can be charac-

terized after processing using either

surface stains or composite resins.

When using surface staining, color-

staining products (G Taub Minute Stain,

G Taub Products) are brushed onto the

surface of the denture base. The dentist

applies these stains to the labial flange

while the patient is in the chair. The tech-

nique involves a thin surface-layer stain

that has limited stability over time. The

stains tend be removed by wear over a

6- to 12-month period.30

Alternatively, composite-based stain-

ing can be used. Once the dentures

have been cured and after finishing and

polishing, the labial flange is reduced

a




by 1 mm of thickness approximately

(Fig 5a). This reduction spans cross-

wise between the two first or second

premolars and 2 to 4 mm vertically from

the denture edge up to the collars and

papillae, which are also reduced. The

surface is then prepared before being

coated with a primer for curing. Color-

ed composite resin is carefully set in

place using a spatula and then worked

with a brush and shaped to achieve

the desired esthetic effects (Figs 5b to

5d). Texture, anatomy, gingivae, color

shading, and distribution are all deter-

mined based on the data provided to

the lab. Polishing is done using abra-

sive pumice, black silk brushes, and

white mounted brushes with calcium

carbonate. Figures 6a and 6b show

before-and-after views of the final es-

thetic result.

Figs 5a to 5d Spot color adjustments, post-

cure staining with composites resins: (a) Tint-

ing window; (b) investing the primer; (c) start of

staining from the denture edge; (d) final appear-

ance at the papillae.

d

cb




Figs 6a and 6b Gingival smile (a) before and (b) after tint-staining.

a

b




CONCLUSIONS

Staining of the labial flanges, a long-

standing technique, still meets patients’

esthetic demands. However, the expan-

sion of tint-based staining techniques

has been hampered by difficulties in-

volved in reverse-manner staining and

by the relatively low reliability of paint-

based staining. Today, the use of micro-

filled composite resins offers laboratories

a simpler, more practical, and more reli-

able solution for meeting the needs of

both patients and dental technicians.

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Esthetics of Artificial Gingiva