Oral Health Group

Treating the “Dreaded Black Triangle”

April 1, 2014
by David Clark, DDS

Sometimes a particular case comes along that appears, at first glance, overwhelming. This case fits that description (Figs. 1–3). However, when Michael emailed my office and inquired regarding flying across the country to have me treat him, I had fortunately done many cases involving hundreds of teeth using the Bioclear matrix system to treat dentitions afflicted with black triangles, albeit none of this magnitude. I felt absolutely confident that we could achieve a good outcome. The trick was to disassemble the case into bite-sized pieces. This case presents many excellent questions and the additional challenge of severe facial abrasions. I will first review background of black triangles and of lower incisor complications and then proceed with the presentation of the clinical procedures used to treat this particular patient.

FIGURE 1. Pre-operative view of black triangle case. Notice the pursing of lips and forced smile of a patient who is embarrassed by the esthetics of the lower teeth.


FIGURE 2. The receded papilla height of the anterior teeth was not significantly lower than that of the posterior teeth, ruling out a surgical approach.

FIGURE 3. This view demonstrates the unique “twisted butter knife” anatomy of the lower incisor tooth.

One third of adults suffer from black triangles, or more appropriately referred to as open gingival embrasures.1 Besides being unsightly and prematurely aging the smile, black triangles are prone to accumulate food debris and excessive plaque.2 A recent study of patient attitudes found patient dissatisfaction with black triangles ranks quite highly among esthetic defects, ranking third following carious lesions and dark crown margins.3 If you go online and Google “dental black triangles”, you will view thousands patient black triangle questions, and of patient complaints and lawsuits resulting from adult orthodontic cases and post-periodontal therapy papilla loss. This clinical and esthetic dilemma demands more attention from our profession. The caveat is that until now, there has been no predictable, minimally invasive approach for treatment. Today, instead of improvising and struggling, I have developed a specific predictable protocol and matrix (US patent #8,393897) to treat this pervasive problem.

The esthetics of the lower teeth are often overlooked or simply ignored by many dentists. Recently a fellow passenger seated next to me on a flight was intrigued by the photos that were on my laptop. He asked “Why do dentists only seem to treat the upper teeth when the lowers look all jacked up? Do they think no one notices? It looks ridiculous to have perfect top teeth and ugly bottom teeth!” In addition, as we age, the lower incisors become more visible as the facial muscles change.

Lower incisors present their own unique restorative challenges. The incisal edge is broad and thin mesio-distally. The root, in contrast, is very broad bucco-lingually. Imagine a butter knife that has been bent at 90° in the middle of the blade. This anatomic curiosity creates demanding draw issues for a porcelain laminate or full crown preparation. A lower incisor with significant recession leads to a mutilatory tooth preparation for porcelain. When I had an opportunity to show this case to the top ceramists in Toronto and Seattle, their answer was refreshingly candid,” Dr. Clark, to treat this case properly with porcelain laminates would require you to mutilate these incisors.”

Like many clinicians, Michael’s dentist in North Carolina hadn’t heard of the Bioclear Matrix System (Clinical Research Dental) and was unfamiliar with injection over-molding of teeth with composite. Therefore he was leery of treating Michael with “bonding”. In fact Michael’s wife had coincidentally been treated for black triangles in North Carolina and the composites literally fell off the teeth after a few months. At that point, Michael decided to cross the country for a different solution because porcelain veneers and periodontal surgeries did not appeal to him as ideal treatments. After he saw the “black triangle” articles on the internet and videos on YouTube, he opted to fly to the west coast for treatment.

After spending many hours working with manufacturers and tens of thousands of dentists, I have compiled “a top 5” list of composite and porcelain fallacies that have steered dentists away from minimally invasive composite treatments for black triangles or has doomed their previous attempts, leaving them gun-shy to try it again.

1) “Acid Etching cleans the tooth”. False. Phosphoric acid barely touches plaque. Biofilm is so tenacious and we forget that phosphoric acid removes the mineral, not the organic component of tooth surfaces. Biofilm is mostly organic, not a mineral. This residual biofilm at the margins is likely the number one reason why class V and interproximal composites turn brown at the margins. No bonding agent can bond to biofilm, and most dentists are leaving biofilm on their hard to access margins.

2) “A stronger dentin bonding agent is the answer”. False. They (the manufacturers) keep selling us new and improved dentin bonding agents with higher and higher dentin bond strengths. The problem is twofold; first of all in a case like this, most dentists are bonding to plaque, calculus, and contaminated dentin and no resin bonds to biofilm. Secondly, with the Bioclear approach; uncut, blasted, and rinsed etched enamel is leveraged to provide the bulk of the retention and reliance on the dentin is lessened. We can trust enamel bonding.

3) “A full crown is better”. False. If you were the patient with otherwise healthy teeth, would you choose full crowns? Consider that a full crown destroys 70 percent of coronal tooth volume with a 10 to 20 percent chance of eventual resultant pulpal death.

4) “A porcelain veneer is better than bonding”. In a case like this, False. First, porcelain veneers cannot reach far enough to the lingual, so the space is blocked from view with a “wing” of porcelain but becomes a plaque trap on the lingual. Secondly, bonding a porcelain veneer to this much cervical enamel should make you nervous. Very nervous.

5) “Direct bonding is too difficult”. In the past this may have been true. But today, False. In the modern resin era, we utilize anatomic Bioclear matrices injection molded with an excel
lent microfill like Filtek Supreme Ultra, creating an ideal flowable/paste composite interlace.

First, I consulted two renowned microscope equipped periodontists. I normally would have immediately excluded the surgical option based on this patient’s situation, but in this case, because of the severity of the embrasures attrition, I felt that a second and third opinion were warranted. In addition if a follow up surgical approach were needed, the periodontist would already be on board.

Dr. Peter Nordlands’s summary: “Dear David, the papilla height across the lower anterior teeth is located at the same level as all of the other adjacent papillae. This means that the individual papillae are not deficient but instead, the patient has suffered incisal edge wear and extrusion of the incisors. Although root coverage could be very predictable, I would recommend a restorative solution as you have so beautifully shown in the Bioclear video. My experience is that surgical papilla reconstruction is most predictable in situations where the papilla has been surgically abused previously.”

Figure 1 shows the functional and aesthetic dilemma. The retracted view (Fig. 2) shows the magnitude of the black triangles on the lower. The patient was far more interested in treating the lowers than the uppers. He returned to the west coast after 6 months to treat the upper black triangles. Facial abrasions and recession tripled the complexity of treatment (Fig. 3).

“Blasting” is a term that we have introduced to describe a noninvasive way to prepare teeth for additive dentistry. The first step is to blast with aluminum tri-hydroxide-air-water high pressure slurry utilizing the Bioclear Blaster. Blasting removes biofilm (plaque and calculus) and strips off contaminated cementum but unlike air abrasion, it does not cut enamel or porcelain. Aluminum Trihydroxide has an ideal hardness and is absolutely the best and fastest way to prepare the tooth for long term adhesion (Figs. 4-8). Once the facial abrasions are restored to the line angles, a well punched rubber dam is placed. The interproximal areas are nicely managed with rubber dam and the Bioclear matrices together (Figs. 9-15). For larger spaces the DC-203 (diastema closure) Bioclear matrices were used and for the smaller spaces, the A-103 (anterior). Attempting to simultaneously place composite to restore the facial abrasions at the same time the interproximal matrices are in position is not recommended.

FIGURE 4. High magnification (8X) of the CEJ area of the tooth. This area is virtually impossible to clean with a prophy cup and scaler, and virtually unbondable unless the dentin is clean and the surface abraded. This area is the Achilles heel of traditional composite dentistry.

FIGURE 5. High magnification (12X) view of the root after step 9. Notice how the gentle blasting has stripped away the contaminated surface dentin and yet leaves the enamel almost undisturbed.

FIGURE 6. –  FIGURE 9. Three perspectives of the Bioclear Blaster preparing the teeth for additive dentistry. The Bioclear “Prophy Plus” unit snaps to the quick disconnect and this or a Prophy-Jet should be part of every bonded procedure’s armamentarium.



FIGURE 9. Step 9 view at low magnification. Facial surfaces that previously had large abrasions are at full contour. Cord is still in the sulcus but not visible in photograph.

FIURE 10. Step 9 at higher magnification.

Once the matrices are slid into position, the entire tooth is acid etched (Fig. 16). The Bioclear method of overmolding teeth is almost the inverse of the old flat mylar matrix technique. In the Bioclear method, the mid facial and mid lingual surfaces are left with some purposeful excess in the composite loading (injection) zone. The interproximals when injection molded, in contrast, will require little or no finishing (Figs. 17-19). The mid facial loading zone can be easily and safely finished back and polished, while the interproximal should require little to no finishing. Dentists, orthodontists and periodontists often ask these patients, “Are these veneers? Are these crowns?” No. This is injection overmolding, an ideal way to perform the ultimate in minimally invasive rehabilitation of the tooth. It is classified as additive dentistry.

FIGURE 11. Bioclear matrix system complete “tower that includes four columns A) Posterior matrices, B)Anterior Matrices, C)Diastema Closure Matrices, and D) Wedging components and ContacEZ sanders.

FIGURE 12. A-103 matrix designed to close small spaces and for traditional fillings on small incisors.

FIGURE 13. DC203 matrix that is especially designed for diastema closure of small teeth.

FIGURE 14. Placement of the Bioclear matrix

FIGURE 15. Four sectional matrices, (Bioclear DC-203 matrices) are placed inciso-gingivally after the contact areas were lightened and gently abraded.

FIGURE 16. 37% Phosphoric acid etchant (3M) is injected under the matrix onto the tooth. The entire tooth should be etched.

FIGURE 17. A familiar site to Bioclear users but perhaps odd to newcomers. The injection molded restoration has interproximal areas that are “porcelainesque” with smooth, rounded contours and flawless surfaces. The facial and lingual surfaces, easy to access and easy to finsh, are a little lumpy.

FIGURE 18. Injection molded canine and bicuspid. Facial finishing is necessary and not difficult. Embrasure areas were difficult to access and easily damaged during finishing before Bioclear. In this case, the embrasure will require little or no finishing.

FIGURE 19.Full arch view after composite overmolding. The case is now ready to be polished.

Having a mirror smooth composite finish makes everyone happy; the patient, the soft tissue and especially you, the clinician (Figs. 20-25). The matte or grainy finishes of the past collect lipstick, biofilm, stain, and feel like cheap dentistry to the patient’s tongue. In the past, only porcelain stayed smooth. Those days need to end now. The first step is using a microfill that holds its shine. I am nearly always disappointed at how miserable the composite finishing systems are that I am asked to evaluate, and how disappointing many of the composite finishes that are presented in dental journals and magazines. The folks at Kerr, 3M, and SS White and CRD have commented that they have never seen polishes like the ones I show in my lecture. That’s probably because most doctors use a manufacturers “system” and frankly those systems are mediocre at best and grossly overcomplicated. To learn about my unique mirror polish (better known as the Clark 30 Second Rock Star Polish) watch it on YouTube: “Dr Clark’s Three Step Composite Polish” or at the Bioclear Learning Center website at Bioclearmatrix.com.

FIGURE 20. Low magnification post-operative view. Cord has been removed.

FIGURE 21. Close-up post-operative view. The rubber dam tissue compression combined with the exacting curvature of the Bioclear matrix; together predictably deliver a regenerated papilla as soon as the rubber dam is removed.

FIGURE 22. 6 month follow up shows unparalleled soft tissue response and complete elimination of the black triangles.

FIGUE 23. The maxillary anteriors were subsequently overmolded to eliminate smaller black tringles and correct chipped incisal edges.

FIGURE 24. A very happy patient, who was grateful to have such a non-invasive, healthy and permanent solution to a problem that was devastating to his smile.

FIGURE 25. Before and after comparison of the lower arch. I offer a 10 year warranty against stain and debonding based on the robust nature of the procedure.

Before the Bioclear matrix and a disciplined approach to composite treatment of black triangles, the 2 dimensional treatments usually ended with
significant compromise in periodontal health. Many cases deboned soon after placement. Others suffered problems with stain. The Bioclear technique is a 3-dimensional treatment of a 3-dimensional problem The interdental papilla serves as both a functional and aesthetic asset. Anatomically ideal interproximal composite shapes that are mirror smooth can serve as a predictable scaffold to regain this valuable gingival architecture. However, the reader is cautioned that to attempt this elective procedure using no magnification, without a strict adherence to dentin detoxification with a blasting appliance, and using a flat matrix/no matrix; non treatment or referral is recommended. Slowly, our profession can change its thought processes, retraining its hands and expand its armamentarium to perform techniques that were previously impossible.OH

Dr. Clark founded the Academy of Microscope Enhanced Dentistry. He is a course director at the Newport Coast Oral Facial Institute and the Director of the Bioclear Learning Center in Tacoma WA. He is on the editorial board for several journals.

He focuses on the re-designing of restorative and endodontic cavity preparations; an overhaul of the tragically outdated GV Black cavity shapes. For composite dentistry, this includes the non-retentive Class II preparation which requires the Injection molding filling technique.

Dr. Clark has developed the Bioclear Matrix System that promises a real advancement for placement of biologically appropriate, esthetically pleasing direct composite restorations for treating minimally invasive Class II preparations, diastema closure, black triangle elimination combined with papilla regeneration, and traditional anterior composites. He has been granted several US patents.

Oral Health welcomes this original article.

Dr. David Clark is the creator of the Bioclear matrix system.


1. Kurth J, Kokich V. Open Gingival Embrasures after orthodontic treatment in adults: prevalence and etiology. Am J Orthod Dentofacial Orthop 2001; 120:116-123

2. Ko-Komura N, Kimura-Hayasi M et al. Some factors associated with open embrasures following orthodontic treatment. Aust Orthod J 2003; 19:19-24

3. Cunliffe J, Pretty I. Patients ranking of interdental “black triangles” against other common esthetic problems. Europ J Pros Rest Dent. 12/2009; 17(4):177-181