Predictable Treatment Technique for Solving the Black Triangle Dilemma

This article will discuss the treatment of mandibular black triangles using anatomically shaped mylar matrices and injection molding heated composite resin utilizing the Bioclear Method. It is the author’s opinion that this is the most conservative and most predictable way to treat such esthetic dilemmas. If unfamiliar with this technique, clinicians may want to consider its merits as it does not involve any sacrifice of healthy tooth structure, and it embraces the concept of “additive only dentistry”.

Black triangles are a common esthetic issue from which many of our adult patients suffer. These open gingival embrasures cause the patients to look older, be self conscious and collect food and plaque on a daily basis¹. Surveying patients has shown that they dislike black triangles more intensely than either dark teeth or crowded teeth². Often times, this will cause them to search the Internet for ways and treatments to help them close these spaces.

What would be the reasons why a clinician would adopt a new technique or change the way they perform a procedure? In our office, we ask the question, “How does it benefit the patient?” The Bioclear Method is most definitely a way in which the patient benefits in the long run. The biggest and simplest reason is the conservation of enamel. This is achieved through the clinician being able to perform an additive versus a resective procedure, allowing the “banking” and preservation of enamel.

Various other techniques to close these black triangles involve the use of flat mylar or even a posterior (metal) sectional matrix which are often manipulated in frustration when trying to adapt them to the anterior tooth. Other documented attempts use a preop waxup and a lingual putty matrix to guide composite placement. These techniques still leave a lot of unpredictability at the gingival, subgingival and lingual areas. Is it not always better to use the right tool for the job at hand? When using the Bioclear matrix in conjunction with a rubber dam, anatomic subgingival contour is achieved with ease.

If longevity, excellence and patient satisfaction is our desired outcome, it is worth taking a little more time to pay extra attention to detail. Yes, this sometimes means taking additional steps which may “slow us down”, but there will be reward in the outcome. An example of this lies in the first cornerstone of the Bioclear Method; the blasting away of biofilm from the tooth prior to bonding. To do this adequately, we need to visualize the biofilm by painting on disclosing solution (Fig. 3). After rinsing, we can now see the remaining biofilm stained pink (Fig 4). 

In order to achieve the most ideal long-term bond to enamel, meticulously blasting biofilm away using a pressurized aluminum trihydroxide/water slurry in a Bioclear Blaster is the best method (Fig 5). Simply etching of the tooth is not enough for predictable biofilm removal. 

Failure to remove the entirety of the biofilm may result in peripheral staining of the tooth to restoration interface and premature failure of the bonded composite.

Prior to placement of the Bioclear matrix, the TruContact sander is used at the contact area. This has a dual function: first, it removed the biofilm present within the contact that the Blaster could not reach. Second, it will lighten the contact point allowing the ease of entry of the Bioclear matrices.

Once the teeth have been “blasted”, rinsed and dried it’s time to place the Bioclear matrix in the mesial and distal positions. Tuck the matrix beneath the rubber dam by using the rigid Bioclear explorer to ensure a perfect subgingival matrix/tooth interface or margin. After placement, in some cases the Bioclear matrices overlap on the facial. If this occurs, trim them back to leave a small gap between the two matricies which allows for venting of excess injection moulded composite.

Once the tooth is isolated with the Bioclear matrix as seen in Fig. 6, the stage is set for injection molding. The tooth is acid etched, rinsed and dried. Then Scotchbond Universal adhesive (3M) is placed using a mop type brush (Fig. 7). Air thin the Scotchbond Universal adhesive to drive off the solvent and prevent pooling, especially at the gingival interface. It is important to note that at this stage, since there is no exposed dentin present, the adhesive is NOT light cured, only air thinned. 

Then heated Filtek Supreme Ultra Flowable followed with heated Filtek Supreme paste (3M) are injected slowly and under pressure into the anatomic space formed by the two matrices - each step being helped by the previous step to keep flowing smoothly. It is important to follow one with the other relatively quickly as cooling of the composite takes place within the first 20-30 seconds. Overfilling the matrix space is part of the technique as this allows room for cutback when shaping and polishing.

The clinical convenience with this technique is that the matrix will always seal itself off subgingivally, often eliminating the need to finish or polish the restoration with burs in the interproximal area afterwards.

Both the flowable and paste composites are heated to the optimal temperature of 158 degrees F or 70 degrees C using the Bioclear HeatSync Composite Warmer (Fig. 8). Numerous studies have shown the benefits and the safety of heating composites resins prior to use in the mouth, (Fig. 5-7) Interestingly, Filtek is now, as of 2020, the only composite resin to be approved by the FDA for use in its heated state. Some of the other benefits of the Filtek resin for the Bioclear Method are: the exact color match between the flowable and the paste composite (not a guarantee with every company), the nanotechnology of the Filtek resin filler and it’s superior polishability.

Heating both the flowable and paste resin eases the advance of material (by making it more liquid) into the small, sometimes tight spaces where the matrix- tooth interface is at too acute of an angle for room temperature paste composite. After matrix removal, that trusted mylar finish is left intact and in contact with the gingival tissue. This allows for the beautiful newly established curvature to be easily flossed and sets the stage for future good gingival health (see radiograph Fig 9). 

Lastly, the Bioclear Method can be used to regenerate lost or flattened papillae. By restoratively re-establishing the interproximal contact gingivally within 5.5 mm of the interdental crestal bone, as demonstrated by Tarnow, regeneration of the papilla incisally to its proper position will take place 8.

The ultimate goal with the Bioclear Method is to create a monolithic, highly polished restoration. Monolithic because the end strength of the restoration will be higher than a layered restoration. Highly polished because this is what creates the stain resistance. The polish that is achieved with the Bioclear Method is something that gives the clinician ultimate satisfaction. The simplified 3-step “rock star” polish (3M Coarse Disk, Magic Mix paste (Bioclear), Shape and Shine cup (Clinician’s Choice)) will always deliver a mirror-like finish. Following each of these steps is crucial to achieving the long-term stain resistance and excellence we desire for our patients when eliminating their black triangles. (Fig. 10). This technique of using modern adhesive dentistry is sure to please both clinician and patients in search of the ultimate in esthetics and conservatism.