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 Table of Contents  
REVIEW ARTICLE
Year : 2020  |  Volume : 4  |  Issue : 1  |  Page : 17-22

Black gingival triangle in orthodontics: Its etiology, management and contemporary literature review


1 Consultant Orthodontist Private Practitioner Clove Dental, Bangalore, Karnataka, India
2 Private Practitioner SanDiego, Calfornia, United States of America

Date of Submission11-May-2020
Date of Decision31-May-2020
Date of Acceptance05-Jun-2020
Date of Web Publication28-Jul-2020

Correspondence Address:
Dr. Sameera Athar
Consultant Orthodontist Private Practitioner Clove Dental Bangalore, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sidj.sidj_17_20

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  Abstract 

The interdental papilla is extremely important for an esthetic smile. Black triangles, also known as gingival embrasures, are defined as the embrasures cervical to the interproximal contact that is not filled by the gingival tissue architecture of periodontal protection. These spaces are the foremost negatively ranked gingival factor by layman. Management of black triangles require high-quality diagnosis, and a multidisciplinary approach must be considered mandatory to attain a successful clinical outcome. Much of which is applicable is instinctive from severely complicated periodontal regeneration and implant therapy. This review will discuss the definition, etiology, classification, and various deliberations required in handling the case of a black triangle. The methods used here for selecting the topic were repeated exposure to the cases of a black triangle by the author's clinical practice. The material was selected by extracting out the content by studying the journals in all the fields of dentistry and formalizing all the obtained data together into one complete article.

Keywords: Black triangle, classification, etiology, management


How to cite this article:
Athar S, Jayadev S. Black gingival triangle in orthodontics: Its etiology, management and contemporary literature review. Saint Int Dent J 2020;4:17-22

How to cite this URL:
Athar S, Jayadev S. Black gingival triangle in orthodontics: Its etiology, management and contemporary literature review. Saint Int Dent J [serial online] 2020 [cited 2020 Aug 8];4:17-22. Available from: http://www.sidj.org/text.asp?2020/4/1/17/291025


  Introduction Top


The interdental papilla could be a part of the gingiva that fills the space between the two adjacent teeth. This papilla not only acts as a biological barrier for the periodontal structures' underneath, but it also has a very important role in esthetics. The interdental papilla could be a key to anterior esthetics, and its loss or short interdental papilla may lead to a black gingival triangle. The black triangle can even cause phonation problems, furthermore creating space for food and plaque accumulation.[1] Another study assessed patients' perceptions with regard to the number of visible triangles and their severity, showing that in patients, they found the presence of gingival embrasures, the third most disliked esthetic problems after caries and crown margins.[2] Kokich et al. demonstrated that patients and clinicians found black triangles >3 mm to be less attractive.[3]

A study has also estimated that 15% of the adolescent patients who underwent orthodontic treatment for crowding of maxillary incisor expected the presence of a black gingival triangle at the end of treatment.[4] Kurt and Kokich[4] had samples of 337 patients and with 4500 records of two private orthodontic practices with a sole reason to assess the prevalence of black triangle between maxillary central incisors after treatment. This study showed the prevalence of incomplete papillae between maxillary incisors in about one-third of the population.[5]

But, what could be the reason for the appearance of black triangle, that it is so common?

The reasons are multifactorial, with the fragility of the gingival papilla playing a significant role in the prevalence of the black triangle. Vascular supply to the papilla is proscribed. The papilla is nourished entirely by the capillary vessels of periodontal ligament and the crestal bone, which extend coronally. The papilla is the most terminal end of the gingival microvasculature, and the capillary loop runs inferior to the oral epithelium of the attached and free gingiva. Classic studies have shown that the capillaries do not continue into interdental concave col area.[6]

The methods/reason used for selecting the topic was repeated exposure to the cases of black triangle by the author's clinical experience. The material was selected by extracting the content by studying the journals in all the fields of dentistry and formalizing the obtained data altogether into one complete article. This review aims to focus on the etiological factors that predispose the occurrence of black triangles and to debate the management of those situations.


  Etiological Factors Top


Studies have documented that the etiology of the black gingival triangle is multifactorial[7] [Figure 1]. Papillary dimensions are often changed, thanks to many of the subsequent reasons.
Figure 1: Etiological factors of black triangle

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  1. Aging of the patient
  2. Gingival biotype
  3. Interproximal space between teeth
  4. The distance between interproximal contact and the crestal bone
  5. Tooth morphology related to the abnormal crown and the shape of the restoration
  6. Distance between the roots
  7. Diverging roots, which can follow orthodontic treatment.


Aging of the patient

Systemic conditions such as osteoporosis[8] as well as age[9] have been suggested as generalized risk factors for the presence of black triangle. Ko-Kimura et al.[9] assessed the relation between age and presence of black triangles after orthodontic treatment and concluded that open gingival embrasures were more frequently found in patients over the age of 20, than in younger patients. To explain this phenomenon, Chang[10] measured the papillary height on standardized periapical radiographs of maxillary central incisors in 180 adults and found that the interdental distance increased and papillary height decreased with age.

Gingival biotype

Siebert and Lindhe[11] classified the biotype into “thin and scalloped” [Figure 2] and “thick and flat” biotypes. Becker et al.[12] classified biotype into the following three groups: flat, scalloped, and pronounced scalloped. Scalloped thin tissue is more likely to react to trauma and inflammation by the recession, while flat-thick tissue reacts with a deeper periodontal pocket. The thin periodontal biotype is friable, escalating the danger of recession following crown preparation and periodontal or implant surgery. Thick biotype is better than thin biotype. Thick biotype is fibrotic and resilient, making it resistant to surgical procedures with a bent for pocket formation. While the interdental gingival tissue possesses biological tissue memory, the rebound of the gingival tissue is more likely with thick rather than thin biotype. Therefore, a thick biotype is more conducive for implant placement, resulting in favorable esthetic outcomes.
Figure 2: Thin and scalloped

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Interproximal space between teeth

The size of the interdental width has relevance to the presence of black triangle. On an average, the interproximal contact point in patients with black triangles is shorter or is located 1 mm more incisally than in the patients with normal gingival embrasures. Martegani et al.[13] studied the measurement of interproximal width with periapical radiographs, and their statistical analysis concluded that when the inter-radicular distance is over 2.4 mm, the presence of full papillae in anterior maxillary teeth becomes less likely. This can be irrespective of the bone-level distance to contact points.

The distance between interproximal contact position and the bone crest

The increase in the distance from the alveolar bone crest to the interproximal contact is suggestively associated with the presence of black triangles, consistent with the classic study from Tarnow et al.[14] When the space from the contact point to the alveolar bone was less or to an adequate of 5 mm, the papilla was present in about 98% of the time, while at 6 mm, it dropped to 56% and at 7 mm, it had been only present 27% of the time. These findings have shown that the papilla will extend only to a limited distance from the alveolar crest to the interproximal contact point. Wu et al.[15] also reflected Tarnow's result on 200 sites in 45 randomly selected adults investigating anterior maxillary teeth.

Tooth morphology and abnormal crown and restoration shape

Divergent or triangular-shaped crown forms are related to black triangles [Figure 3]. Ahmad[16] mentioned that the triangular-shaped teeth have divergent roots along with a thicker interproximal bone, which leads to sporadic bone loss compared to square-shaped teeth. However, the incidence of black triangle in square-shaped teeth is reportedly less in comparison with triangular-shaped teeth. This was considered to result in shorter interproximal distance from the alveolar crest to the free gingival margin in square-shaped teeth as compared to triangular-shaped teeth.[16] Burke et al.[5] showed the association between tapered crowns and black triangles' presence. The planning of the contact area in crowns, bridges, and any kind of restoration also effects the interdental area.
Figure 3: Triangular-shaped crown of 21

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Distance between roots

Cho et al.[17] investigated the existence of interdental papillae at certain distances from the contact point to the alveolar crest, based on the interproximal distance between roots. They found that the number of papillae that filled the interproximal space decreased with increasing interproximal distance between roots, and also have been more prominently decreasing with the increasing distance from the contact point to the alveolar crest.

Diverging roots, which might follow after orthodontic treatment

Burke et al.[5] reviewed 500 orthodontic records and emphasized that orthodontic movement of crowded anterior teeth can separate the roots and stretch the interdental papilla, thereby increasing the presence of a black triangle between the incisors at the end of treatment. The authors had also raised a concern regarding orthodontically moving the roots very near to one another, jeopardizing the interdental bone and interdental papilla because of lack of embrasure space. This might be a risk with the increasing number of techniques that depend on interdental tooth stripping for space creation during alignment.


  Classification Top


The loss of the interdental papilla is classed by Nordland and Tarnow.[18] This classification is based on the following three anatomical signs: the interdental contact point, the foremost coronal point of cemento-enamel junction (CEJ) on the interproximal surface, and therefore the most apical point of the CEJ on the labial surface. The following four classes were identified [Figure 4]:
Figure 4: Classification of interdental papilla

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  • Normal: The interdental papilla fills the niche, up to the apical extension of the interdental contact point
  • Class I: The tip of interdental papilla is placed between interdental contact point and therefore the most coronal point of CEJ at the interproximal surface
  • Class II: The tip of the papilla is placed between the foremost coronal point of CEJ at the interproximal surface and therefore the most apical point of CEJ at the labial surface
  • Class III: The tip of the interdental papilla is present at the CEJ or it is apically to the foremost apical point of CEJ at the labial surface.



  Management Top


Eliminating the risks of developing black triangles isn't always possible; multidisciplinary understanding of management strategies is helpful. Implementing general principles of periodontal treatment is also very useful.

Restorative approach

The treatment of black triangle through restorative considerations can be done by varying the position of the aim of contact, with ceramic veneer or crown. If possible, add pink porcelain to the restoration to control the presence of interdental papilla loss.[19],[20] The benefits of such methods are biocompatibility of the material, with stability in color and a nonporous surface. The disadvantages are the extreme skills required to handle and mend the material.

In addition, restoration of cervical mesial regions will reduce the presence of gingiva by changing the coronal shape. Composite is inserted near the gingival sulcus as a guide for the formation of an interdental papilla. The advantage is that the composite has many colors that are stable and wear resistant; the most recent generation of dental bonding agents enables the bonding of composites to dentin. The drawback with this approach is that there could be changes in bonding, discoloration, and fluid seepage through the dental interface and composite.[21]

Orthodontic approach

Orthodontic treatment is aimed toward reducing black triangle space, which is carried out by shifting the contact points from incisal into the apical region. Divergent roots are generally associated with black triangle space. Divergent roots also can be caused by improper bracket placement, so it is important to investigate with a periapical radiograph always before bonding of the bracket.[20]

Gingival embrasures are often caused by the direction of movement of the teeth. During the movement of the tooth toward the lingual side, the gingival tissue thickens, and the embrasure space is moved toward the occlusal direction, whereas the movement of the teeth toward the labial side will cause the gingival tissue to become thinner, making the embrasure space to move more apically, creating the black triangle.

The presence of bone also governs the volume of soft tissue within the gingival embrasure region. Closing the diastema by orthodontic means compresses the soft tissues filling up the embrasure chamber.[20]

The orthodontic method which can be carried out for black triangle space closure is the interproximal enamel reduction by using diamond strips to reshape the mesial surface of the upper central incisors. Approximately 0.5–0.75 mm of enamel is reduced within the interproximal region, which increases the point of contact and reduces the gingiva. Decreased interproximal enamel on teeth with triangular crowns will change the aim of contact on an outsized area, thus forming a gingival embrasure [Figure 5].
Figure 5: Interproximal reduction to reshape the incisors and bring the roots closer

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Prosthodontic approach

A straightforward but effective procedure for managing a decent gingival recession and loss of interdental papillae is the use of gingival prosthesis. The gingival prosthesis could be a removable covering the missing gingival tissue.[21] Such prosthesis is indicated with cases of >5 mm space between interdental papilla and the contact point in whom surgical procedures are contraindicated. The contraindications of prosthetic procedures are for cases with poor and unstable periodontal health, those with compromised oral hygiene, and in patients with high caries risk. Advantages: Noninvasive, easy maintenance, splinting on the teeth are often done, and more economical. Disadvantages: Requires the patient's cooperation, repeated food impaction, and inhabitants bacterial growth, which further hampers the color of the prosthesis. Prosthodontic treatment can be carried out by various materials such as auto and heat polymerizing synthetic resins, rigid and flexible materials copolyamide and soft silicone material.[21]

Surgical approach

Periodontal plastic surgery has a long history of overcoming the unsightly appearance of a black triangle. However, the papillae's inadequate blood supply is the main limiting factor in all augmentation and reconstruction surgical approaches. Patients with a thin gingival biotype are vulnerable to recessions with which they are more prone to the occurrence of black triangles. A thicker gingival biotype is having better vascularization that facilitates the healing process.[20] Surgical techniques aim to reshape, maintain, or repair soft tissue between teeth with implant.[22]

Surgical approaches include:

  • Papilla recontouring to reshape soft-tissue contours
  • Papilla preservation to shift the gingival margins more apically, developed by Takei[1] and Cortellini and Tonetti[19]
  • Papilla reconstruction; the technique could be a combination of pedicle flap and papilla preservation.[20],[21]


Surgical techniques could also be carried out with pedicle flaps, free gingiva, and subepithelial connective tissue graft. Some case reports have demonstrated success with subepithelial animal tissue graft and orthodontic therapy. These reports are consistent with Wu et al.,[15] where the flap surgery has shown better results than free gingival graft. de Oliveira JD, et al. stated that the techniques with pedicle flaps showed better results than free gingival graft techniques[20] because the bottom of the pedicle provides the blood supply.


  Discussion Top


The loss of interdental papillae will result in a condition known as a black triangle. The interdental papilla is one of the most important factors that clinicians will have to pay attention to, especially in terms of esthetics. Various factors affect the case of interdental papillary loss, including the height of alveolar crest, interproximal spacing, the soft tissue, buccal mucosa thickness, and the extent of contact areas.

A study carried out in 2001 by by Kurt and Kokich[4] to examine post-treatment open gingival embrasures in 337 adults orthodontic patients, assessed the association different etiological factors with digital images of pretreatment and post treatment periapical radiographs, the prevalence of posttreatment open gingival embrasures was found to be 38%. The pretreatment maxillary central incisor rotations and overlap were found to be statistically insignificant when related to the posttreatment open gingival embrasures. The authors also concluded that the alveolar bone-interproximal contact distance post treatment with >5.5 mm with a short, incisively placed contact were found to be statistically significant with an association to the occurrence of black triangles. An increased divergence of root angulations with triangular-shaped crown forms and embrasure areas larger than 5.09 mm were also correlated with open gingival embrasures. Furthermore, black triangles found in this study were seen to have the most significant association with increased alveolar bone–interproximal contact distance and increased root angulation. This investigation indicated that black triangles are common in adults who had undergone orthodontic treatment and that posttreatment results were expressive in their formation.

Kokich et al.[3] and Kurt and Kokich[4] further examined whether the distance between the interproximal contact point and the alveolar crest of bone affected the amount of the interproximal papilla. Through their study, the following data were received:

  1. 5 mm or less – Interdental papilla always present
  2. 6 mm – Papilla present 56% of the times
  3. 7 mm or more – Papilla usually missing.


Tanaka et al.[23] found that the prevalence of open gingival embrasures was higher in orthodontic patients over 20 years of age and that the resorption of the alveolar crest is more likely to lead to this problem. Open gingival embrasures were found in 40% of the patients undergoing orthodontic treatment. On radiographic examination, it was found that patients who had undergone orthodontic treatment had decidedly more bone loss than the patients who had not undergone treatment. Thus, this study indicated that the occurrence of open gingival embrasure is significantly related to alveolar bone loss secondary to orthodontic treatment.

Ko-Kimura et al.[9] conducted a study including eighty orthodontic patients (33 males and 47 females) between the age group of 15 and 31 years. Open gingival embrasures were found in 43.7% of all patients, with the prevalence being 66.7% in patients over 20 years. The amount of crowding was taken into consideration, and it was found that the occurrence of black triangles was related to it in the following manner:

  1. Less than 4 mm crowding – 42.8%
  2. 4 mm to 8 mm crowding – 41.2%
  3. 8 mm and more crowding – 50%.


The period of orthodontic treatment was also considered and was found not to be statistically significant in 42% of patients in shorter treatment time group and 44.4% of patients in the more extended treatment time group. In conclusion, it was drawn that black triangles were more frequently found in patients over 20 years of age than in younger patients, and were associated with a higher degree with the resorption of the alveolar crest.

Agarwal et al.[24] conducted a case series that included reconstruction of open gingival embrasures; the distance between the tip of interdental papilla and incisal edge was measured at the follow-up visits. The distance between interdental papilla and incisal edge at 3 months and 6 months remained stable. The results showed an increase in sulcus depth by about 1.19 mm and improvement in the contour of interdental tissues in 51% of cases, and in 38.46%, the interdental papilla completely obliterated the open embrasures.

For the selection of any surgical procedures related to the reconstruction of the gingival tissue, attention has to be given to adequate blood intake. As there are regional limitations to papillary regeneration, any grafting procedure will become difficult. Therefore, the selected surgical technique should be able to provide adequate blood supply from the flap to the graft material to maintain the integrity of the papilla as well as to prevent the occurrence of flap necrosis.


  Conclusion Top


Black triangles impact directly on the perfect smile esthetics and performance of the function. Multidisciplinary teamwork helps in managing black triangles more effectively. Orthodontics, periodontics, and restorative dentistry, all with strategic interventions when combined in synergy, are effective for management when the presence of black triangle is unavoidable. The etiology of black triangles is multifactorial, but research suggests that a distance between the alveolar crest and interproximal contact point appears to be the foremost significant factor contributing to its occurrence.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Takei HH. The interdental space. Dent Clin North Am 1980;24:169-76.  Back to cited text no. 1
    
2.
Cunliffe J, Pretty I. Patients' ranking of interdental “black triangles” against other common aesthetic problems. Eur J Prosthodont Restor Dent 2009;17:177-81.  Back to cited text no. 2
    
3.
Kokich VO Jr., Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental esthetics. J Esthet Dent 1999;11:311-24.  Back to cited text no. 3
    
4.
Kurt J, Kokich VG. Open gingival embrasures after orthodontic treatment in adults: Prevalence and aetiology. Am J Orthod Dentofac Orthop 2001;120:116-23.  Back to cited text no. 4
    
5.
Burke S, Burch JG, Tetz JA. Incidence and size of pretreatment overlap and posttreatment gingival embrasure space between maxillary central incisors. Am J Orthod Dentofacial Orthop 1994;105:506-11.  Back to cited text no. 5
    
6.
Zuhr O, Rebele SF, Cheung SL, Hürzeler MB, Research Group on Oral Soft Tissue Biology and Wound Healing. Surgery without papilla incision: Tunneling flap procedures in plastic periodontal and implant surgery. Periodontol 2000 2018;77:123-49.  Back to cited text no. 6
    
7.
Pugliese F, Hess R, Palomo L. Black triangles: Preventing their occurrence, managing them when prevention is not practical. Seminars Orthod 2019;25:175-86.  Back to cited text no. 7
    
8.
Chow YC, Eber RM, Tsao YP, Shotwell JL, Wang HL. Factors associated with the appearance of gingival papillae. J Clin Periodontol 2010;37:719-27.  Back to cited text no. 8
    
9.
Ko-Kimura N, Kimura-Hayashi M, Yamaguchi M, Ikeda T, Meguro D, Kanekawa M, et al. Some factors associated with open gingival embrasures following orthodontic treatment. Aust Orthod J 2003;19:19-24.  Back to cited text no. 9
    
10.
Chang LC. The association between embrasure morphology and central papilla recession. J Clin Periodontol 2007;34:432-6.  Back to cited text no. 10
    
11.
Seibert JL, Lindhe J. Aesthetics and periodontal therapy. In: Lindhe J, editor. Textbook of Clinical Periodontology. 2nd ed. Copenhangen, Denmark: Munksgaard; 1989. p. 477-514.  Back to cited text no. 11
    
12.
Becker W, Ochsenbein C, Tibbetts L, Becker BE. Alveolar bone anatomic profiles as measured from dry skulls. Clinical ramifications. J Clin Periodontol 1997;24:727-31.  Back to cited text no. 12
    
13.
Martegani P, Silvestri M, Mascarello F, Scipioni T, Ghezzi C, Rota C, et al. Morphometric study of the interproximal unit in the esthetic region to correlate anatomic variables affecting the aspect of soft tissue embrasure space. J Periodontol 2007;78:2260-5.  Back to cited text no. 13
    
14.
Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol 1992;63:995-6.  Back to cited text no. 14
    
15.
Wu YJ, Tu YK, Huang SM, Chan CP. The influence of the distance from the contact point to the crest of bone on the presence of the interproximal dental papilla. Chang Gung Med J 2003;26:822-8.  Back to cited text no. 15
    
16.
Ahmad I. Anterior dental aesthetics: Gingival perspective. Br Dent J 2005;199:195-202.  Back to cited text no. 16
    
17.
Cho HS, Jang HS, Kim DK, Park JC, Kim HJ, Choi SH, et al. The effects of interproximal distance between roots on the existence of interdental papillae according to the distance from the contact point to the alveolar crest. J Periodontol 2006;77:1651-7.  Back to cited text no. 17
    
18.
Nordland WP, Tarnow DP. A classification system for loss of papillary height. J Periodontol 1998;69:1124-6.  Back to cited text no. 18
    
19.
Cortellini P, Tonetti MS. Microsurgical approach to periodontal regeneration. Initial evaluation in a case cohort. J Periodontol 2001;72:559-69.  Back to cited text no. 19
    
20.
de Oliveira JD, Storrer CM, Sousa AM, Lopes TR, de Sousa Vieira J, Deliberador TM. Papillary regeneration: Anatomical aspects and treatment approaches. Rev Sul Brasil Odontol 2012;9:448-56.  Back to cited text no. 20
    
21.
Ravishankar Y, Srinivas K, Sharma SK, Shameen KP. Management of black triangles and gingival recession: A prosthetic approach. Indian J Dent Sci 2012;4:141-5.  Back to cited text no. 21
    
22.
Kaushik A, Pk P, Jhamb K, Chopra D, Chaurasia VR, Masamatti VS, et al. Clinical evaluation of papilla reconstruction using subepithelial connective tissue graft. J Clin Diagn Res 2014;8:ZC77-81.  Back to cited text no. 22
    
23.
Tanaka OM, Furquim BD, Pascotto RC, Ribeiro GL, Bósio JA, Maruo H. The dilemma of the open gingival embrasure between maxillary central incisors. J Contemp Dent Pract 2008;9:92-8.  Back to cited text no. 23
    
24.
Agarwal M, Mittal M, Mehrotra S, Agarwal A. Black triangle and its reconstruction: A review. J Dent Sci Oral Rehabil 2011;4:55-6.  Back to cited text no. 24
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]



 

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Introduction
Etiological Factors
Classification
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