Injection Overmolding for Aesthetics and Strength, Part 1: Finishing Orthodontic Cases Using Direct Composite
Written by David Clark, DDS Tuesday, 05 August 2014 13:12
Orthodontics has seen significant advances during the past decade. In spite of these advances, there is no magic wand or silver bullet when teeth are undersized. In addition, there are a staggering number of adult ortho cases that produce the dreaded black triangle, an aesthetic dilemma that is considered to be more unsightly than the crowding that led to the ortho in the first place. Part one of this 2-part article will discuss the treatment of undersized teeth, and part 2 will discuss post-ortho black triangles.
BIOCLEAR INJECTION overmolding VERSUS “BONDING”
“Bonding” sounds a lot like “Bondo,” which is a cheap way to fix a wrecked car fender. Bonding and Bondo have given composite resins a bad name (Figure 1). Go online and read how some “cosmetic dentistry experts” tell the public that bonding is inferior to porcelain veneers. This statement is due in large part to a flawed delivery system, lack of training, and a dearth of proper engineering principles for composite, leaving some cases to look like poor asphalt patchwork, sooner or later. The Bioclear approach is not bonding. It is injection overmolding. Instead of just patching the tooth, the Bioclear Matrix and method allow the entire tooth to be over-molded with variable thickness composite. Why perform patchwork when you can routinely pave the whole street? Properly done, it is superior to porcelain for both black triangles and young post-ortho patients. This 2-part article series will first introduce the Bioclear Matrix and method, and how it works to completely injection over-mold cases with undersized incisors, and then will examine injection over-mold teeth with black triangles.
Identical Twins With Peg Laterals
At first glance and at a straight facial view (Figure 2), these twins might just look like the need a “little bonding” on their peg laterals (Figures 3 and 4). However, a closer profile angled look (Figures 5 and 6) revealed that all 4 incisors were undersized, and simply adding to the lateral incisors or even just the 4 anterior teeth would produce inappropriately sized teeth. With the Bioclear method, “bonding to hide gaps,” in my practice, has evolved to “360° composite overmolding” for a strong, predictable, and permanent solution.
|Figure 1. Patchwork style of bonding, as seen here on the central incisors, has served to hurt the reputation of composite resins. Note the excess translucency, small holes full of brown stain, and most importantly, an ignorance of the larger issues that could have been addressed had an up-to-date technique, as described herein, been used.||Figure 2. Identical twins with undersized teeth and peg laterals. When compared with the postoperative photographs, the faces seem a little sad and straining to smile. Most patients dislike tooth gapping far more than dark teeth or crowded teeth.|
|Figure 3. Post-orthodontic, preoperative smile
photograph of one of the twins.
|Figure 4. Retracted post-orthodontic, pre-restorative view of the maxillary anterior sextant.|
|Figures 5 and 6. Lateral views of the peg laterals and general spacing dilemma. This view demonstrates that a comprehensive approach adding to all 6 anterior teeth, using both anterior and diastema closure matrices, was indicated.|
After a discussion with the treating orthodontist, the overmolding procedures (to include teeth Nos. 6 to 11 for both patients) were then also approved by the 2 patients and their parents.
The Treating Orthodontist’s Thoughts
In his own words, Dr. Jerrold S. Johnson stated: “A tooth size discrepancy caused by narrow maxillary lateral incisors is a very common problem faced by orthodontists. Changing the tip and torque of the maxillary incisors, or reducing the mesial-distal dimensions of the lower incisors, can often solve the discrepancy without the need for future maxillary restorations. However, when the discrepancy is large, as was the case with these twin sisters, restorations are a necessity. Determining the exact position to place the maxillary lateral incisors can be difficult, especially when working with various restoring dentists, each with different professional opinions. What impressed me the most about the Bioclear Matrix method was the ability to modify the shape more apically on the mesial and distal aspects of the incisors, thereby changing the emergence profile and giving more flexibility for the position of the teeth. When discussing where to place the lateral incisors orthodontically, Dr. Clark was less concerned about their exact position than I was, and yet his results were excellent.”
Rethinking Priorities in the Veneering of Teeth
Spend enough time at an aesthetic academy and your head begins to spin when it comes to cases like this. Sadly, there is so much focus on diagnostic wax-ups, proportionality rules, nuances of multiple shading of porcelain or composite, etc, that the average general dentist walks away thinking, “I can’t afford to spend that much time and energy on these cases!” In addition, in the author’s opinion, too much focus is spent on pleasing the other dentists in the room with not enough attention given to pleasing the patient and to the soft-tissue response. Frankly, a good number of the “fancy porcelain cases” have mediocre soft-tissue health and are simply inappropriate for a 14-year-old patient. Traditional direct bonding cases may look alright for a few months but then begin to stain, often having horrific overhangs, or residual black triangles, or all 3 problems.
|Figure 7. Selection guide for the 3 most popular Bioclear diastema closure matrices.|
|Figure 8. The DC-203 matrix is shown along with the complete kit. (Note the dramatic change in
subgingival emergence profile that will stimulate true papilla regeneration.) The green dotted line shows the typical notch that should be cut with the Bioclear microscissors to accomodate the papilla.
Many doctors using Bioclear have commented that the ideal and varied shapes of the matrices (Figure 7) have allowed them to throw away their diagnostic wax-ups and just get to work. This is a bottom-line approach. The spaces must be closed. The matrix dictates the appropriate shape and emergence profile. The patient needs to love his or her smile. It must be smooth, strong, and healthy. The change in emergence profile must begin subgingivally, which requires the use of a diastema closure matrix (Figure 8) (Table).
Trimming the Bioclear Matrices
When the patented Bioclear Matrices were first introduced, clinicians were happy to finally have a matrix that truly had multiple anatomic shapes. It is quite puzzling that no one had invented matrices with these shapes before. After trial and error, we have discovered that for young patients, or for patients with “young bone,” the gingival apron needs to be trimmed with special Bioclear microscissors to duplicate the significant rise and fall of the attachment (Figure 8, green dotted line). These instructions are now carefully spelled out in the new users’ guide and in the video of this case (available at the Web site bioclearmatrix.com). This quick but crucial modification allows the matrix to seat up to 3.0 mm deeper with a hand-in-glove-like fit. The matrix can be surprisingly comfortable as it slides gently and neatly into the sulcus. The absence of bleeding and stability are remarkable. One of the reasons that a flat Mylar strip causes gingival bleeding is that it slices the delicate soft tissue. Think of the soft tissue having the same softness as a ripe strawberry. It needs tender loving care!
“Just Say No!” to Layering
Layering is “fancy pants” dentistry that is often the enemy of the good. Dentists, physicians, and other discriminating patients fly from both North America and abroad to my office, seeking microscope-enhanced, minimally invasive, monolithic Bioclear composite resin restorations. None of them ask for layered composites. What do patients want? Color uniformity (a bright but believable color), no preparation of the tooth, no porcelain, no tissue inflammation, no black triangles, no staining, no roughness, no fractures, and an assurance that the restoration will be as strong as porcelain. My office guarantees Bioclear restorations for 10 years against stain and debonding. In contrast, my office warranty on porcelain is 5 years. While the offer of a 10-year warranty is strictly a personal business decision that I have made uniquely for my practice, doctors should be confident that these over-molded restorations should hold up as well as porcelain. Most dentists, myself included, can’t satisfy that list with hand-stacked multi-shade composite. I ask this every time in my lectures: “Who is the boss?” The answer is, “The patient,” and then I add, “and the soft tissues.” Masters of layering, such as Drs. Bob Margeas and Jeff Brucia, have extraordinary long-term results, but they will freely admit that layering is more artistic than is usually asked for by their patients. In reality, most dentists who dabble in layering often have problems later and find the procedure to be a labor of love that is unprofitable and eventually disappointing to patients. If you love to layer and are good at it, then you can certainly layer using the Bioclear Matrix system. If not, say goodbye to layering.
“Just Say No!” to Translucency
This case, as most are in my practice, was restored with Filtek Supreme Ultra Body flowable and regular composites (3M ESPE). The most popular shade used in my office is B-1. We have most patients do tray bleaching before the teeth are restored, allowing the routine use of B-1 body composite. We don’t use Enamel Shade, Dentin Shade, or Translucent Shade. The Body shade is a perfect balance of translucency and opacity, permitting me to focus on more important issues like shape and strength. In addition, the flowable and regular composite shades match perfectly.
DETAILS OF THE CASE
The brevity of this article does not allow a complete description of this case. However, a narrated video is available at dentistrytoday.com. This HD video, shot through the lens of an operating microscope (Global Surgical) has an abundance of tips, fully explaining the sequencing issues.
“Blasting” is not simply air abrasion that uses very aggressive aluminum oxide. In order to adequately remove biofilm, the teeth are painted with disclosing solution and then meticulously blasted with pressurized aluminum trioxide/water mix (Bioclear Blaster [Bioclear Matrix Systems]). To achieve an ideal bond to enamel or dentin, clinicians must be reminded that phosphoric gel etchant alone cannot be relied upon to remove dental plaque. The use of rubber dam isolation is often dismissed when doing anterior aesthetic work as unnecessary or, worse, counterproductive. As the inventor of Bioclear Matrix Systems, I have found that, in most cases, the amount of interproximal gingival retraction afforded by the rubber dam is ideal for predicting the amount of static tension needed to generate or regenerate a papilla. The rubber dam also protects the soft tissues when blasting is performed to remove pesky biofilm.
|Figure 9. The pre-polished width of the central incisors was measured before moving on to teeth Nos. 10 and 11. (Note: The central incisors must match perfectly.)||Figure 10. Two trimmed Bioclear DC203 matrices were placed on the mesial and
distal of tooth No. 7, creating a crown-like containment system.
|Figure 11. A 37% phosphoric acid gel was injected into the matrices. (Note: Make sure to start the injection apically to ensure etching of the entire tooth.)||Figure 12. The entire tooth was etched for 20 seconds, then rinsed thoroughly and air-dried.|
|Figure 13. Adhesive was quickly painted completely over the tooth, then air-thinned, but not light cured. When there is little to no dentin involved, it is better not to cure the adhesive independently of the composite resin.||Figure 14. The tip of the flowable composite (Filtek Supreme Ultra Body [3M ESPE]) was then inserted 360° around the gingival margin, facilitated by the wetting action of the yet-to-be cured adhesive.|
|Figure 15. High-magnification view of the initial placement of composite. This “flowable composite hip” was not individually light cured in this case because these post-orthodontic teeth were a little mobile. The radius of the matrix actually allows the matrix to push the teeth apart slightly so that no delayed wedging will be necessary.|
Once the central incisors were over-molded using Bioclear A-101 and a-102 matrices (not pictured), they were measured (Figure 9) and sculpted with a rough finish. The rest of the left side was completed one tooth at a time, and then the same with the right side. Tooth No. 7 shows several steps (Figures 10 to 15).
The Clark Three-Step Polish
The Bioclear method is unique in that the loading zone (injection zone) is left with intentional excess, while the difficult areas (such as interproximal and subgingival areas) are essentially “porcelainesque” by virtue of the composite-to-Mylar finish effect. The goal is to then safely and quickly grind back the loading zone, marrying it to the glassy smooth Bioclear Mylar finish zone.
The 3-step polish technique is as follows:
- Shofu Brownie with water coolant at medium speed,
- Coarse lab pumice in a disposable cup,
- The polishing cup (Jazz Polishers Supreme [SS White Burs]) on the facial surfaces (Figure 16); and the one-step Jazz polisher cone on the lingual.
The postoperative photos reveal a patient-friendly, strong, and incredibly stain resistant finish (Figures 17 to 21).
Upon subsequent routine visits, the patients’ mother reported that random people often stopped the twins in the street and said, “You 2 have the most beautiful teeth I’ve ever seen!” The family noted that their facial posture improved after the work. Patchwork composite bonding rarely produces such noticeable and life-altering dental makeovers.
|Figure 16. Once the regular composite (Filtek Supreme Ultra Body) was injected into the pool of uncured flowable composite, the tooth was contoured in the loading zones and then polished with a polishing cup (Jazz Polishers Supreme [SS White Burs]).||Figure 21. Postoperative view of the twins. Note the changed countenances of their faces in comparison to the preoperative faces. “Double Trouble” no more! Retracted postoperative view of the composite over-molded dentition, at 3 weeks.|
|Figure 18. Occlusal postoperative view. The buccal-lingual thickness (recommended to be between 1.5 to 2.0 mm) of the teeth shown here is sufficient to give porcelain-like strength.||Figure 19. A 6-week postoperative view with breathtaking soft-tissue response, regenerated papillae, and an undulating surface that breaks up the specular highlights to create a bright yet believable aesthetic outcome.|
|Figure 20. Smile image showing ideal proportionality of the additive dentistry.||Figure 21. Postoperative view of the twins. Note the changed countenances of their faces in comparison to the preoperative faces. “Double Trouble” no more!|
Materials and Treatment Planning
In Figure 18, the reader should carefully study the thickness of the teeth. Our research and follow-up studies have shown that if the incisal edge of the composite is at least 1.5 mm thick and the entire tooth is over-molded, we can expect no incisal edge fractures. In the same way that monolithic all-ceramics (such as lithium disilicate and full-zirconia crowns) do not break, monolithic (nonlayered) composite restorations created using the Bioclear method of composite overmolding can have surprising durability. Unlike many of the porcelain veneer cases presented in dental journals in the past, most porcelain veneers are fabricated as a monolithic material (single material and shade), using either pressed or milled porcelain. While very durable, these restorations are generally more monochromatic than layered porcelain veneers. And, any significant multichromatic effects that were achieved via staining techniques have a limited lifespan.
In short, using the Bioclear overmolding technique, we have moved to color uniformity, and patients like it. Furthermore, dentists appreciate the strength and durability. (Note: I use the term color uniformity and not monochromatic in a purposeful way. Patients prefer uniformly colored teeth, so I have changed the lexicon to reflect the new thinking.)
In the past 24 months, the author has placed hundreds of Bioclear over-molded anterior composites and has seen no incisal edge fractures. Layering and patchwork with composites creates compromised strength. Composite overmolding, in contrast, produces extraordinary toughness. Furthermore, not a single patient asked for translucent incisal edges. Better, faster, prettier, and stronger composites are the new catchphrases that we embrace.
“When should I use Bioclear over-molded composites versus porcelain?” is the new big question that I am being asked by doctors at lectures and hands-on courses. Here is a good rule of thumb: age matters. We know that a lifetime of occlusion will selectively wear down the enamel on lower incisors if we use porcelain. If the patient is less than 40 years old, I suggest composite as a first choice. Any time the author is only doing a limited case (ie, one to 3 anterior teeth), composite is again preferred; this is because trying to prepare and match one or 2 porcelain laminates to natural teeth can be very invasive, the color matching excruciating, with all this being a potential profit killer. After age 40, and in cases that I do 6 to 10 teeth, patients are told that either porcelain or composite is great.
The true infinity edge (featheredge on nonprepared enamel) margin is only possible with direct composites. A composite margin can easily be thinned and polished to have an almost microscopically imperceptible margin. Composites’ infinity edge benefits both color matching and pink aesthetics and nearly always has better gingival health than microscopically fitted porcelain margins.
There are 6 new factors that have changed the game in “additive dentistry.” They are as follows: modern resin design, breathtaking composite polishing, heated composite, anatomic and diastema closure matrices, injection overmolding combining flowable and regular composite, and the trends away from both layering and incisal translucency. Modern techniques (as illustrated in this article) and composite resin with the Bioclear method can have the same face-changing and life-altering effect as porcelain rehabilitation.
Disclosure: Disclosure: Dr. Clark is the owner of Bioclear Matrix Systems.
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