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*Corresponding author: E-mail: bkzarea@judent.org;
British Journal of Applied Science & Technology
6(1): 1-7, 2015, Article no.BJAST.2015.061
ISSN: 2231-0843
SCIENCEDOMAIN international
www.sciencedomain.org
Black Triangles Causes and Management: A Review
of Literature
B. K. Al-Zarea
1*
, M. G. Sghaireen
2
, W. M. Alomari
3
, H. Bheran
4
and I. Taher
5
1
Faculty of Dentistry, Aljouf University, Sakaka-Aljouf, Saudi Arabia.
2
Department of Prosthetic Dentistry, Faculty of Dentistry, Aljouf University, Saka-Aljouf, Saudi Arabia.
3
Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan.
4
Department of Dentistry,
Ministry of Health, Aljouf, Saudi Arabia.
5
Faculty of Medicine, Aljouf University, Sakaka-aljouf, Saudi Arabia.
Authors’ contributions
This work was carried out in collaboration between all authors. Author BKA designed the study,
performed the statistical analysis, wrote the protocol, and wrote the first draft of the manuscript and
managed literature searches. Authors MGS, WMA, HB, IT managed the analyses of the study and
literature searches. All authors read and approved the final manuscript.
Article Information
DOI: 10.9734/BJAST/2015/11287
Editor(s):
(1) A.A. Hanafi-Bojd, Department of Medical Entomology & Vector Control, School of Public Health, Tehran University of
Medical Sciences, Iran.
Reviewers:
(1)
Wetende Andrew, Department of Periodontology and Community dentistry, School of Dental Sciences, University of Nairobi,
Nairobi, Kenya.
(2)
Angelo Troedhan, Faculty of Dentistry, Health Science University Vientiane, Laos; Center for Facial Aesthetics Vienna,
Austria.
Complete Peer review History:
http://www.sciencedomain.org/review-history.php?iid=764&id=5&aid=7209
Received 8
th
May 2014
Accepted 1
st
November 2014
Published 15
th
December 2014
ABSTRACT
Open gingival embrasures often pose complex functional and esthetic problems. Management of
open embrasures requires careful evaluation of the underlying causes. A team approach comprising
of general dentist, an orthodontist, and a periodontist is critical. The authors reviewed a total of 51
articles including review of the literature using the terms ‘black triangle’; ‘open gingival embrasure’;
‘interdental papilla’ and interproximal contact area’. These articles provided information regarding
etiology, diagnosis, and management of black triangles. There are several risk factors leading to the
development of black triangles. These factors include periodontal disease, loss of height of the
alveolar bone relative to the interproximal contact, length of embrasure area, root angulations,
interproximal contact position, triangular-shaped crowns and aging. Treatment of black triangles
often requires an interdisciplinary approach, involving of periodontal; orthodontic and restorative
treatment.
Review Article
Al-Zarea et al.; BJAST, 6(1): 1-7, 2015; Article no.BJAST.2015.061
2
Keywords: Aesthetic; black triangles and interproximal contact areas.
1. INTRODUCTION
The field of aesthetic dentistry is governed by
rules and values, and should be studied from
both subjective and objective point of view.
Perception varies between individuals and is
controlled by social background and personal
experience [1]. Aesthetics has been studied from
different perspectives.
Aesthetic has been studied from different
perspective to obtain an esthetically pleasing
smile; many components should be in harmony
and symmetry. These include gingival display;
lips contour and outline; and tooth shape; color;
size; and position [2]. Consequently, open
gingival embrasures or black triangles are
complex aesthetic and functional problems that
are noticeably unaesthetic and negatively affect
smile (Fig. 1). Open gingival embrasures “black
triangles” are defined as the embrasures cervical
to the interproximal contact that is not filled by
gingival tissues [3] (Fig. 1). Consequently, Open
gingival embrasures or black triangles are
complex aesthetic and functional problems.
Among these problems is that they are
noticeably unaesthetic which negatively affects
the smile, facilitate retention of food debris which
can negatively affect the health of the
periodontium [2]. Black triangles are present in
more than one third of all adults but are more
frequent in adult patients who suffer bone loss
[4]. Treatment plan should be discussed with
patients before starting dental treatment [3,5].
Fig. 1. Open gingival embrasures or black
triangles
Amongst the main objectives of restorative and
orthodontic treatment is preserving papilla and
avoiding black triangles in the esthetic zone. The
etiology of open embrasures is known to be
multifactorial. Etiological factors include aging,
periodontal disease, loss of height of the alveolar
bone relative to the interproximal contact,
length of embrasure area, root angulations,
interproximal contact position, and triangular-
shaped crowns. Its management varies
depending on the etiological factor, but is
favorably managed by a team work usually
including restorative, orthodontic and periodontic
treatment. In certain cases correction of these
open embrasures is not straightforward and may
increase both the complexity and duration of
treatment. Sometimes, the decision to close the
embrasures or not is difficult especially when the
open embrasures are small.
Several studies have investigated the impact of
open gingival embrasures. Kokich et al. [5] found
that orthodontists considered a 2 mm open
gingival embrasure as noticeably less attractive
than an ideal smile with normal gingival
embrasure. Open gingival embrasures slightly
greater than 3 mm were considered less
attractive by both general dentists and the
general population. Cunliffe [6] found that
interdental "black triangles" were rated as the
third most disliked aesthetic problem below
caries and crown margins.
In this review, the authors highlighted the
important etiological factors that predispose to
the occurrence of the black triangles. In addition
to the common biological factors, dimensional
changes of papilla during orthodontic alignment,
the relevant consequences of periodontal
disease treatment and iatrogenic treatment
mishaps such as poor veneers and crowns are
factors have also been discussed as factors that
may lead to black triangles.
Prevalence and Patient Attitude
One third of adults have unaesthetic black
triangles [5]. Other studies found that black
triangles were found in 67% of the population
over 20 years of age compared with 18% in the
population under 20 years of age [3,7,8,9]. A
recent study of patient attitudes found patient
dissatisfaction with black triangles to rank quite
high among aesthetic defects, ranking third
following carious lesions and dark crown margins
[8].
Al-Zarea et al.; BJAST, 6(1): 1-7, 2015; Article no.BJAST.2015.061
3
2. ETIOLOGICAL FACTORS AND
MANAGEMENT
2.1 Black Triangles and Periodontal
Diseases
Tarnow’s study [4] has become a standard in
calculation of crestal bone to contact area
distance when predicting the stable papilla
height. His study, based on 288 patients, showed
that when the contact point was within 5.0 mm of
the crestal bone, the papilla was present in 100%
of samples. However, when the distance was 7.0
mm, the papilla was present in only 27% of
samples (Table 1) [4]. Moreover, pocket depths
greater than 3 mm will lead to increased plaque
retention, inflammation, and possibly gingival
recession [7]. Wu YJ also found that a distance
of 5, 6, and 7 mm resulted in an open embrasure
in 2, 44, and 73% of the cases respectively [10].
These observations indicates that papilla was
present in almost 100% of the cases if the
distance from the alveolar crest to the contact
point was 5 mm or less. When the distance was
more than 7 mm, most patients had an open
gingival embrasure. Another study by Zetuhas
reported similar results [7].
Table 1. Adopted from Tarnow et al. 1992 [4]
Bone-contact distance (mm)
% Full papilla
3 100
4 100
5 98
6 56
7 27
8 10
9 25
10 0
For those with periodontal diseases, it is the
bone loss that increases the distance between
the contact points and alveolar crest and
eventually creates open gingival embrasures.
Tarnow’s 5.0 mm rule might be skewed in a
favorable or unfavorable direction because there
are many factors that determine the presence of
black triangles such as the root angulations,
teeth shape, occlusion and previous trauma. For
square-shaped teeth with wide contact points,
the chances of 'black triangles' is minimal
compared with triangular teeth having narrow,
more incisally positioned contact points.
Furthermore, the degree of interproximal fill is
also dependent on the periodontal biotype. A
thick periodontal biotype encourages interdental
fill, while a thinner tissue type creates un-
aesthetic hollow gingival embrasures [8].
Interdental width seems to be critical in papilla
presence. An increased interdental space results
in wide papillae base that may be helpful in
increasing blood supply to the papilla tip.
However, too wide of an interdental distance can
be detrimental, stretching and blunting the tip of
the papillae and increasing the likelihood of the
black triangle [9]. An extreme form of this is the
absolute loss of papilla in periodontal disease
that has been associated with loss of the
interdental papilla because of alveolar bone loss.
Chronic periodontitis and tooth brush trauma are
other factors that may cause open embrasures.
If interproximal tooth brushing is causing gingival
recession, and loss of interdental papilla, it
should be discontinued until the tissue recover
[11,12]. Plaque accumulation and gingivitis are
probably higher in people with crowding, but host
susceptibility and other factors may also play a
contributory role in the occurrence of open
gingival embrasures, especially in patients who
have been previously treated for periodontal
disease [11]. Such patients need to increase
their efforts to enhance periodontal maintenance
and oral hygiene to avoid further bone loss and
recession. The interdental papilla is a small
fragile area with minor blood supply which seems
to be the major limiting factor in all surgical
reconstructive and augmentation techniques [10].
Most surgical techniques published involve
gingival grafting, but show only limited success
because of insufficient blood supply [10,11].
However, some case studies have reported
some degree of success with the combination of
sub-epithelial connective tissue grafts and
orthodontic therapy [13,14]. A large number of
techniques have been proposed to reconstruct
the interdental tissues including a pedicle flap
[15]; semilunar coronally repositioned flap
[16,17]
;
envelop type flap [18]
;
autogenous
osseous and connective tissue grafts [19] and
microsurgery. However, pedicle flaps have
provided better results than free gingival grafts
as reported by WuYJ. [10]
2.2 Black Triangle and Orthodontic
Management
Tooth morphology determines two aspects of
gingival undulations. Firstly, the basic tooth
forms: circular; square or triangular; determine
the degree of gingival scallop. Circular (oval) or
square teeth produce a shallower gingival
scallop, while triangular teeth form the opposite
Al-Zarea et al.; BJAST, 6(1): 1-7, 2015; Article no.BJAST.2015.061
4
as pronounced scallop. The latter predisposes to
the black triangles especially with a thin biotype
which has a propensity for recession [5].
Furthermore, root divergence of adjacent teeth
either occurs naturally or as a result of improper
orthodontic treatment [20], triangular-shaped
incisor crowns [21] long and narrow teeth [22]
are all etiological factors for black triangles.
Treatment should be designed to create
parallelism of the roots and a favorable position
of the proximal contact point of the crowns. In
cases where incisors are malposed or
overlapping they should be up-righted and
moved mesially to correct the inclination of the
roots. The mesial cementum enamel junctions of
each incisor will then be closer to each other’s
causing the stretched transeptal fibers to relax.
The same soft tissue will fill in the gingival
embrasure, which has been narrower [23].
Kurth et al. [20] noticed that a mean root
angulation of 3.65° in normal gingival
embrasures and an increase in root divergence
by 1° increased the probability of occurrence of
an open gingival embrasure from 14 to 21%.
Bracket repositioning can be performed to
converge maxillary incisor roots to reduce or
eliminate the open gingival embrasures as
paralleling divergent roots decreases the severity
of a black triangle. During orthodontic treatment
bracket’s slots should be bonded perpendicular
with the long access of the tooth and not to the
incisal edge. If brackets placement is done based
on incisal edges, greater root divergence may
result causing an open gingival embrasure [10].
In case where the crowns are triangular,
interproximal reduction (IPR) of enamel between
the triangular crowns will broaden the contact
area and also move it gingivally leading to
reduced open gingival embrasures. Typically,
0.5-0.75 mm of enamel is removed with IPR for
correction of black triangles [10].
The severity of crowding does not influence the
incidence of open embrasures as they were
found to occur in a similar percentage in patients
with incisor crowding of less than 4 mm and
those with 4-8 mm of incisor crowding. It was
found that when the crowding was more than 8
mm, the occurrence of black triangles increased
by only 7% [20]. However, these results were not
statistically significant. It was also found that the
orthodontic treatment duration did not have any
significant effect on the occurrence of open
gingival embrasures [3].
2.3 Black Triangle and Restorative
Management
Natural interproximal embrasures are
constructed with a wide range of cervical shapes
and varying root proximities. The gingival usually
adapts to a wide range of teeth cervical area
shapes. Clinicians can create convenient
interproximal shapes if the restorations are
smooth and without sharp margina ledge.
Composite, porcelain laminate veneers; pink
auto-cure and heat-cured acrylics, resins and
thermoplastic acrylics, as well as silicone-based
soft materials [24,25,26] are all treatment
modalities for closure of open gingival embrasure
space. Composite and porcelain laminate resin
can be extended into the gingival sulcus,
however, care must be taken not to impinge on
the interdental tissue or violate the biological
width [24].
Clark presented a feature case of management
of open gingival spaces that includes restorative
treatment followed by papilla regeneration [25].
He used flowable composite resin rather than
composite paste for the first increment since
paste composite would be nearly impossible to
place in such “claustrophobic” area without voids
and without disturbing the anatomically shaped
matrices (Figs. 2a and 2b). In an attempt to
reduce the interproximal space and improve
esthetics and phonetics Barzilay [26] used two
types of removable prosthesis; Molloplast B soft
lining material and clear acrylic facing (Fig. 3).
However, his type of prosthesis suffers from few
limitations. Retention may be difficult, and
because of the inherent porosity of the silicone-
based material, staining and plaque
accumulation may be a problem. Therefore, it
would be better if it is made of heat-curd acrylic
resin (Figs. 4a and 4b). Retention can be further
enhanced by providing implant supported
prosthesis when space is available.
Porcelain veneers are considered an excellent
choice to eliminate or reduce the black triangle.
Nevertheless, care must be taken when planning
for anterior crowns or veneers in order to
avoid occurrences of black triangles.
This complication can be avoided by proper
planning and pre-operative periapical X-rays to
carefully assess the level of the alveolar crest
bone. The interproximal contact area can be
extended apically to compensate for some bone
resorption, and the contact area should be
Al-Zarea et al.; BJAST, 6(1): 1-7, 2015; Article no.BJAST.2015.061
5
Fig. 2a. Before treatment
Fig. 2b. After treatment with flowable
composite
Fig. 3. Molloplast B soft lining material and
clear acrylic facing
placed at a point within 5.0 mm of the crestal
bone as stated by Tarnow [4].
In a complete denture wearer, knowledge of the
ideal papilla location for optimal aesthetics
originated from classic literature on prosthetic
tooth selection and arrangement. Frush and
Fisher [27] attempted to establish guidelines for
proper papilla form to enhance denture
aesthetics. They described the ideal papilla
position and shape in relation to the interproximal
contact location and morphology; it was thought
that the papilla could enhance a youthful
appearance as a complimentary factor in age
interpretation.
2.4 Black Triangle and Implant
Close attention to both soft tissues and hard
tissues around teeth and implants before, during,
and after restorative procedures will greatly
increase the probability of successful outcomes
[28]. The presence of the dental papilla is critical
in achieving an esthetic single tooth dental
implant restoration. The vertical and horizontal
distances from the implant to the natural teeth,
and the distance from the restoration contact
point to the bone level of the natural teeth are
paramount criteria that could be utilized to predict
the presence or absence of the papilla. These
criteria are based on studies involved natural
teeth and implant restorations [4,29,30].
To preserve the interdental papilla and allow for
adequate oral hygiene, 1.5 - 2.0 mm of space is
needed between the implant and the tooth on
each side. Therefore, 7 mm of mesiodistal space
must be created between the adjacent teeth [31].
After the appropriate amount of coronal space
has been determined, it is necessary to evaluate
the inter-radicular spacing. The minimum inter-
radicular distance required is generally 5-7 mm
for a single implant placement.
Grunder [32] reported an excellent papilla results
for single tooth implant restoration even when the
distance from contact point to the implant bone
was 9 mm, whereas, Tarnow et al. [4] concluded
that all papilla were present in the natural teeth
when 5 mm or less was present from the contact
point to the crestal bone and less than 50% when
the distance was over 6mm. In another study by
Tarnow et al. [29] crestal bone loss was
evaluated in relation to horizontal inter-implant
distance. In this study it was reported that
increased crestal bone loss would occur if the
inter-implant distance was less than 3 mm. Their
findings lacked statistical analysis that examined
significance at an acceptable level of confidence.
In another study by Mark et al. [33] describing
the relationship between horizontal implant-tooth
distances and the presence of papilla,’ they
reported that the distance from the contact point
to the implant increased the chance of loss of
papilla significantly. They also found that there
was no difference between delayed or immediate
provisionalization and papilla scores.
Al-Zarea et al.; BJAST, 6(1): 1-7, 2015; Article no.BJAST.2015.061
6
In cases where two implants are placed adjacent
to each other, open gingival embrasures are
more pronounced [34]. Selective utilization of
implant with a smaller diameter at the implant-
abutment interface may be beneficial when
multiple implants are to be placed in the esthetic
zone so that a minimum of 3 mm of bone can be
retained between them at the implant-abutment
level [29].
3. CONCLUSION
Open gingival embrasures or black triangles
often pose complex aesthetic and functional
problems that are noticeably unaesthetic and
negatively affect the smile. A multidisciplinary
approach must be considered mandatory if a
successful clinical outcome is to be achieved. All
etiological factors and treatment alternative must
be discussed with the patient before starting the
treatment
COMPETING INTERESTS
Authors have declared that no competing
interests exist.
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Peer-review history:
The peer review history for this paper can be accessed here:
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