December 10, 2019
by Peter Walford, DDS; Wayne Wright, DDS
Many patients present in their mid-forties with shortened anterior teeth. While not severe enough to warrant crown placement, early composite augmentation restores cuspid guidance and incisal length before wear destroys anterior teeth, flattens posterior cusps and exposes dentin generally throughout the mouth.
This article, written by Dr. Peter Walford, a general dentist and dental educator on Hornby Island, British Columbia, describes a method using composite resin to augment 12 anterior teeth showing dentin exposure and mild disfigurement in a 45-year-old male (Fig. 1). The restorations were performed by Dr. Wayne Wright of Guelph, Ontario, who has done hundreds of cases in this fashion. Using a laboratory- generated wax up (Fig. 2), an accurate transparent stent (Fig. 3), conservative preparations (Fig. 4), and Teflon tape to isolate teeth from adjacent teeth (Fig.5), upper and lower sextants were treated, one tooth at a time, with warmed composite resin placed in the stent (Fig. 6), completing the case in one day (Fig. 7).
This method controls esthetics, saves considerable time, restores cuspid protection, ensures occlusion and disclusion are maintained, and follows a consistent pattern akin to what one would expect from fixed laboratory reconstruction. Often no anesthetic is required.
In the usual dental practice context, provided vertical dimension is not altered, the patient may be eligible for insurance coverage. Thus, many more patients can be helped with this modality without the formidable cost of full mouth reconstruction. The efficiency and durability of the method makes it a routine approach to an oral condition generally untreated today with a consistent solution.
Discussion: Relationship To Conventional Fixed Full Mouth Reconstruction
This article illustrates a conservative case, but the method applies to more advanced cases showing destruction up to 50% of anterior crown length. These cases have a satisfactory lifespan if protected from bruxism, acidity, occlusal prematurities and other etiological factors. In due course definitive laboratory treatment may be substituted, spreading patient expense over time and requiring shorter crown appointments. Acceptance by TMJ and musculature is solidly verified and retained when one begins in this trial format.
This system resolves many transitional issues in full mouth reconstruction, when the mouth must be augmented as an entirety. Direct adhesive augmentation is more durable than cemented temporary crowns, often more attractive, and imposes less pulpal stress than full coverage preparation.
Beginning with casts and waxed-up design, there is little guesswork compared to freehand or matrixed treatment. Control does not drift away from a unified outcome.
RESTORATIVE METHOD: Diagnostic Phase: Models, Articulator
The patient, a 45-year-old male, was examined for occlusal disharmonies driving his excessive wear. His models were screened for common bruxism triggers: inclined prematurity sites, such as second molar palatal cusps, mesio-lingual of upper bicuspids, plunger cusps, and over-erupted unopposed molars.
In the anterior, initial screening of cuspid function revealed lack of centric contact, inadequate disclusion due to loss of cuspid height. Adverse inter-arch relations such as exaggerated Curve of Spee or canted maxilla were not present. Passive eruption and alveolar change were not seen as they often are in more extreme cases. Co-factors such as erosion, sleep apnea, caries, and wear from porcelain opposing enamel were not present. The main etiology appeared to be clenching and “Type A” personality factors driving muscular hyperactivity.
The patient was educated to expect reasonable lifespan from treatment, to accept precautionary nightly use of a bruxism guard, and to understand the benefit of this treatment for preservation of his smile and protection from posterior breakdown. Because dental insurance was available, pre-authorization of the likely claim was initiated. Often treatment can be shared between year-ends, to utilize two annual limits to complete the case, but in this case, it was not necessary.
Obtaining Perfect Models
Impressions were taken at the outset of the first appointment with a slow-setting alginate, which allowed time to swipe material into occlusal fossae before inserting trays, leading to models with accurate occlusal surfaces free of errors and bubbles. Hard laboratory stone was used to prevent chipping of weaker stone products during handling. Stone set was accelerated by using
slurry from a lab model-grinder as the mix water, and a de-bubblizing spray prior to pour ensured accurate reproduction. Thus, very accurate models were ready within 45 minutes of impression-taking.
Obtaining A Face Bow Record And An Occlusal Registration: Tripod Method
A leaf gauge of selective thickness was used between the anterior teeth to disclude all teeth and allow the condyles to seat posteriorly, because habitual anterior positioning, driven by interdental disharmonies, is a frequent factor in excessive wear. We do not want these disharmonies to set the patient’s registration in their habitual intercuspation, but rather, into their TMJ relation. A polyvinyl registration was taken in this slightly open jaw relation.
A face bow record was taken, and the models mounted while the patient was still in the office. Again, a stone slurry was used to accelerate the set of the mounting plaster.
Verifying Accuracy Of Registration And Articulator Mounting
The articulator–mounted case was compared chairside to the patient’s mouth, looking for accurate reproduction in the mount. Condylar inclinations were adjusted from averages as needed. Side-shift was adjusted using stock plastic shims until the articulator accurately represented the patient’s excursive envelope (Figs. 8 & 9).
Laboratory Phase: Prescription, Photos, Wax-Up, Dentist Approval
Once satisfied with the articulator phase, a laboratory prescription was generated. Key factors such as incisor width and length, cuspid length, tip morphology and overall “personality” of the smile was communicated. A standard form systematizes the communication. Intra-oral and extra-oral photos were sent to enhance the technician’s understanding of the facial morphology. Once the dentist was satisfied with the wax-up (Figs. 10 & 11), a duplicate model was produced, from which a typical vacuum-generated stent was made (Figs. 12 & 13).
Patient Approval Phase: Stent fabrication and Mock-up
The patient returned to see the waxed-up model and duplicate model compared it to his presenting appearance. From this he began to better grasp the extent of his dental breakdown. Chairside, using a suitable shade of self-cure crown and bridge temporary acrylic, an intra-oral mock-up was made in the typical clear vacuum-generated stent. Note that these stents (Figs. 12 & 13) are not sufficiently accurate to use in the restorative phase, but inexpensively help to convey a very realistic idea of the treatment result for the patient. The patient was encouraged to take this acrylic overlay home to his family overnight for further approval.
Once the patient approved, a treatment appointment was made. In this case, two hours were necessary for each arch, and these appointments were on the same day. Treatment could also have been divided over a two-day span.
A Highly Accurate Transparent Stent
A stent made through both vacuum and pressure adaptation of heated material was made of the patient-accepted model. The stent material, Copyplast™, and its accompanying pressure vessel are available through laboratory supply companies for in-house fabrication, or stents can be provided through select laboratories. Figure 14 shows its thickness and how it is trimmed onto the alveolar surfaces both buccally and lingually.
The lower arch was treated first. The first step was to insert shimstock between posterior teeth (Fig. 15), and verify occlusal contact on both sides of the mouth. After each tooth was augmented, this step was repeated to verify that centric occlusion had not been altered.
Where does the inter-arch room come from to permit augmentation? Often, in this method, the jaw is being repositioned distally in treatment to offset an acquired forward centric driven by inclined prematurities. Often, second molar relationships remain untouched and the degraded forward occlusion, now retruded, has sufficient room to occlude with incisors at full length or nearly full length.
This is the significance of a full
occlusal diagnosis, and the reason for the care taken in mounting the models on a properly occluded articulator. When there is insufficient room obtained, the mandibular incisors can be augmented towards the lingual (Fig. 11), gaining apparent height without developing premature occlusion. These lingual-inclined augmentations function in protrusion and protect exposed dentin from accelerating wear. This was the case in this treatment.
Restoring cuspid protection is the key to a durable outcome, preventing the incisors from contact in lateral excursions. As well, all dentin exposure was shoed. This is because dentin has a Brinell hardness of 6.8, enamel 9.8, and paste resins are at a median of 8.6. As the Brinell scale is logarithmic, one can see that wear is attenuated by a factor of nearly 100 when dentin is protected by resin.
Preparation for Lower Incisor
Buccal and lingual chamfers were made with a small chamfer diamond (Figs. 16-18). Proximal preparation was made with a fine-tipped diamond, (Fig. 19), and entry was made into the incisal dentin with a suitable bur, ¼ round, fissurotomy bur, 329 or 330, as appropriate (Fig. 20). A light reduction of the incisal enamel was also instrumented. If not bur-instrumented, it should be air-abraded. This step eliminates etch-resistant, amorphous, highly fluoridated re-mineralized enamel that is not continuous with the underlying rod structure and optimizes ultimate bonding strength and the durability of the restorations. The interproximal surfaces are freed by passage of metal interproximal strips, such as GC New Metal strips, 600 grit, to facilitate subsequent placement of Teflon tape against the adjacent teeth (Fig. 5). There is no need to break proximal contact in the preparation.
The finished preparation (Fig. 18) features intracoronal and extracoronal retention. There was a definitive finish line on the facial and lingual to aid in marginal finishing.
Restoring Lower Incisors And Cuspids
The prepared tooth was etched, rinsed, isolated from adjacent teeth with Teflon tape, and bonded in a dry field (Figs. 21-23). Applying a full-arch stent precludes the use of rubber dam, so that effective use of aspirators and absorbent products is mandatory, in addition to considerable skill on the part of the dental assistant with the high-volume evacuator. Antisialogogues might be necessary for some patients. As always, contaminated bonding is worthless and must be avoided at all costs.
The Copyplast™ stent (Fig. 25) was filled with warmed paste resin, in this case, 3M ESPE Z-250 Shade A3, previously trial-matched for shade, and adapted interproximally with a plastic instrument before curing. This resin was chosen because its flexural strength is 137 MPa, against a field averaging 120 MPa. This confers resistance to fracture when cantilevered, as in these augmentations. Z-250 has a very fine particle structure of 10 nanometres, which polishes well, and is both metameric and translucent to a degree that works well in conferring a youthful incisal transparency to the finished augmentation. As well, it has a long clinical record in multiple longitudinal trials for good service, free of chipping and fracture. It is also more thermoplastic than most resins, aiding its effectiveness in adapting to these small definitive preparations (Fig. 31). A fine-particle resin with similar properties could be substituted.
Finishing The Augmented Incisor
Excess resin flows over the tape, and use of a 7902 bur (Fig. 26) prepared a pathway for removing flash with a sickle scaler (Fig.27), so that an interproximal serrated blade, such as a Brasseler 9816 10P could be introduced (Fig. 28), and the proximal surfaces then shaped with GC New Metal diamond strips prior to finer polishing with plastic strips. Figure 29 shows a strip being “shoeshined’ across the proximal margin so that the proximal of the restoration follows the line angles of the tooth. This is an important aid in developing realistic contour.
Buccal surfaces were finished with a 7902 and 7901 bur (Fig. 30) and a 5/8”M/F 3M ESPE Sof-Lex plastic disc was used to refine the buccal margin, incisal edge and embrasures (Figs. 33 & 34). Lingual surfaces were shaped and marginated with 7406 and 7404 burs (Fig. 32). The incisal and protrusive contacts were refined with two-colour articulating tape (Fig. 39) and posterior occlusion verified with shimstock (Fig. 14).
Final shaping and finishing were completed with Shofu Brownie and 3M ESPE Sof-Lex spiral polishing wheels (Figs. 36-38). The extent of augmentation is shown in Figure 35.
This process was repeated for the remaining mandibular incisors and cuspids, and the occlusion verified for protrusive contact (Figs. 39 & 40). The patient was dismissed for several hours to rest, with treatment planned in the afternoon to complete his case. Figures 41 through 44 demonstrate the cuspids disclusion pre and post-treatment.
Notice how closely this follows the relationship to that predicted in the wax-up phase (Figs. 10 & 11).
The preparation for the labial surface of the central incisor follows an undulating path across the labial enamel, extending into the inter-lobular concavities found in most central incisors (Fig. 41). This develops a more harmonious blend between resin and incisor, compared to a completely straight finish line from mesial to distal. The same approach may be followed for the maxillary lateral incisor if it shows significant concavities on the labial surface.
Figure 42 shows the finished central incisor preparations on 11 and 21. An indelible black marking pen can be used to blacken the enamel surface, to assist in developing a crisp finish line. Once prepared, ethanol or isopropanol will remove it entirely.
One of the goals of treatment was to close the diastema between 21 and 11. In the preparation, the mesial surface was lightly diamond abraded with a long thin diamond to the gingival line. The Copyplast™ stent was filled with an appropriate amount of resin, the adjacent tooth protected from adhesion with Teflon tape, and the resin cured in place after careful adaptation. Excess was trimmed with the 7902 bur and GC New Metal strips as before (leading to minor gingival bleeding) until it flossed smoothly (Fig. 43).
21 was treated similarly, the wax up and stent providing great control over the line angles, length, and other morphology. This can consume a great deal of time when using conventional matrixes or freehand sculpting diastema closure.
Achieving Cuspid Disclusion
Figure 44 shows the labial chamfer of the right cuspid preparation. The lingual reduction is comparable, but is driven by the presenting occlusion. The finish line was carried gingivally beyond the centric stop of the opposing cuspid. Thus, both the centric stop and the inclined discluding lingual plane will be established in resin. Figure 45 shows the preparation, which, despite minimal incisal reduction, delivers no disclusion. In fact, after re-lengthening the centrals and laterals fully, these teeth are now poised for destruction in lateral protrusion. Figure 46 shows the result after cuspid augmentation, where the cuspid is now protecting the lateral and central incisors, and the full proportional length of youth has been regained. If Figures 10 and 11 are compared to Figures 46 and 49, the close adherence of the final outcome to the wax-up can be seen. Preoperative views in Figures 46 and 47 show he lack of disclusion preoperatively.
Refining Margins and Eliminating Flash
Figure 50 shows the mouth after applying caries detector and air thinning with the suction. Excess resin flash is rendered visible on tooth 32 with this method. When using resins that closely approximate tooth structure in appearance, it is easy to miss marginal flaws, voids, bubbles, overhangs and flash. Application of a dye, such as a caries detector, or disclosing solution, will render these defects visible and lead to proper finishing before dismissal. While labial margins can be finished quite easily by skilled play of light from the mirror, fiber optics, and the operatory light, lingual and proximal marginal flaws are much more difficult to detect. This dye detection method improves the finish of the case in a way not possible otherwise.
Figure 51 shows the finished appearance of the case, with diastemas closed between 13 and 12, and between 11 and 21. There is little to distract the untrained eye from a cohesive appearance, and the vitality of natural teeth is retained.
Refining the Occlusion
In order to distinguish markings from protrusive and centric contact, a two-colour articulating tape, such as AccuFilm II (Parkell Inc.) is used. Figure 52 shows how the protrusive markings in red on the lower arch translate into equivalent markings on the upper arch (Fig. 53). By inverting the occlusal indicator tape, and having the patient close in centric relation, the centric contacts can be distinguished from the protrusive, and occluding surfaces that function in both movements can be identified (Fig. 54). If the paper has dried out, a thin film of petroleum jelly will improve markings.
The diverse theories and schemes of correct occlusion are beyond the scope of this article, but the critical role of two-coloured occlusal tape cannot be overlooked as a method of establishing well-honed and intentionally shaped occlusal function. Today we can also employ digital occlusal analysis such as T-Scan (National Dental) and/or read muscle contraction duration with electromyography to ascertain if we have successfully achieved rapid depolarization and return to resting state muscle activity through our treatments.
There is a period of adaptation before patients habituate to their new occlusion. The patient should be educated to expect the possibility of mild sensitivity and transitory events such as unexpected impacts between incisors while chewing. Before long, chewing and muscle memory develop in harmony with the new envelope.
A review visit was scheduled with the patient, three weeks postoperatively, for minor polishing, adjustments, and verification of all excursions. A bruxism guard is advisable for most cases involving masticatory hyperactivity, and one was fabricated for this patient from impressions taken after treatment was completed (on the day of treatment). It was delivered at the three-week review appointment. The patient was pleased not only with his rejuvenated appearance and new comfort level, but also with the rapidity of the treatment, which was accomplished in one day, the ease (requiring no anesthetic), and the low cost (requiring low laboratory input costs and being eligible for dental insurance coverage).
This restorative method offers a middle path between single-tooth dentistry (without overall control), and complex laboratory-based reconstruction that is unaffordable for the average patient. It represents a hybrid of comprehensive gnathology mated to common adhesive materials, where both patient and practitioner stand to gain. It has wide applications to a broad base of etiologies, is an early intervention approach that reduces the progress of disease, and does not preclude advancement to more permanent treatment in the future.
Oral Health welcomes this original article.
About the Authors
Dr. Peter Walford is a general practitioner on Hornby Island, British Columbia. He has mentored study clubs, lectured nationally, published a number of articles on adhesive dental technique, and demonstrated procedures on the Live Stage at the Pacific Dental Conference for many years. He is a Fellow of the Canadian Academy of Restorative Dentistry and Prosthodontics.
Dr. Wayne Wright is a 1975 graduate of University of Toronto Dentistry. He practices orthodontics in his general practice and has a keen interest in fixed prosthodontics.