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Biomimicry using a Modifiable, Intelligent Shading System in the placement of Direct Layered Composite Resin Veneers in a post-trauma case


Treatment List (FDI classification)
Tooth 11MIB: Direct acid-etched layered resin restoration (complex veneer)
Tooth 21MIDBL: Direct acid-etched layered resin restoration (3/4 crown)

Restorative Material

Lingual Shelf: Amaris TN: Translucent Neutral (VOCO)
Opaque layer: Amaris O3 (deep dentin and cervical locations)
Secondary Opaque layer: Amaris O2 (subsurface dentin and incisal dentin characterization)
Incisal effects: Amaris HT (high translucency) flowable
Facial enamel layer: Amaris TL (Translucent Light)


Adhesive System

Tooth 11MIB: acid-etched 4th generation (Kerr Optibond FL) preparation
Tooth 21MIDBL: acid-etched 4th generation (Kerr Optibond FL) preparation.

Introduction and Chief Complaint

The male patient (16) presented to my service on referral from an endodontist in Auckland.  His tooth 11 and 21 had been subjected to major trauma when he accidentally slipped off a cliff at the age of seven. He reported multiple past root canal attempts with functional failure attributed to coronal leakage and recontamination and esthetic failure associated with dark dental staining secondary to hemosiderin retention and bacterial mass ingress.  Teeth 11 and 21 exhibit old composite restorations described as discolored, uneven and unacceptable, causing anxiety. Adding to this complexity, a repaired sub-gingival perforation was present in the immediate sub-gingival mid-buccal region causing gingival irregularity with a recently resolved periodontal pocket. The distal aspect of 21 had also been under contoured, leaving a sub-gingival shelf or under hang in this region with a deficient emergence profile. The patient desired more even, longer and attractive central incisors but had both financial and residual dento-structural limitations.

Medical History

Conditions: none reported
Medications: none
Allergies: none

Diagnosis and Treatment Plan

Diagnosis

The specific examination began with an extra-oral examination of the patient’s lymph nodes, salivary glands, muscles of mastication and temporo-mandibular joints. His range of motion was 50mm and judged to be within normal limits.

A specific review of his upper anterior dental sextant revealed deepest peri-tooth probing depths of this region to be 4mm in the 21DB region. All other regions measured were recorded as a maximum of 3mm with bleeding on probing. Hard tissue examination revealed a shorter clinical crown on tooth 21 compared to 11. Tooth 21 was also in positioned in buccoversion or proclined compared to 11. The distal aspect of tooth 21 was where the “under hang” existed, and as such, there was a hard tissue deficiency present sub-gingivally affecting the emergence profile from distobuccal to distolingual aspects.  Teeth 13 to 23 were not tender to percussion or palpation, and exhibited no significant clinical mobility.  

Radiographic examination involved a single peri-apical radiograph of the region. Large obturation spaces were noted with the absence of a post structure.  This would require a preparation that was conservative of a maximal amount of the existing tooth structure as the lack of need for a post was again discussed with the endodontist and confirmed as not required before proceeding.

Discussions with the patient revolved around the placement of two direct, layered complex composite veneer restorations to correct his esthetic concern, removing a minimum of tooth structure. Width:height ratios would be improved to better approximate an 0.8:1.0 width:height ratio as per ideal proportions. An option was also given to patient to have bonded porcelain restorations placed, as this would have a positive effect on coronal strengthening. Although the patient and his mother was interested in this option, the patient’s desire for reparability with potential future accidents and financial constraints were the limiting factors. The patient accepted my advice on the placement of direct, layered composite veneers on 11 and 21.


Treatment Plan

  1. Cursory examination (hard and soft tissue): extra-oral and intra-oral
  2. Pre-operative peri-apical radiographs x 1
  3. Informed consent
  4. 12 pre-operative American Academy of Cosmetic Dentistry (AACD) photo series taken
  5. Color mapping
  6. Anesthesia, split rubber dam isolation and preparation
  7. Micro air abrasion (50 micron aluminum oxide)
  8. Etch, bond, direct, layered restoration with Amaris (VOCO) TN, O3, O2, HT and TL for teeth 11 and 21.
  9. Rough primary and secondary anatomy finishing on first day
  10. Confirm color integration, modification as necessary, final contouring and polishing 48 hours later (to wait for resin to set optimally before final polish).
  11. 12 post-operative AACD photo series taken along with post-operative periapical radiograph.


Description of Treatment Including Rationale for Choice of Restorative Material

The patient was a 16 year old man referred to my service for cosmetic dental bonding by a local endodontist in Auckland. The endodontist had completed obturations of 11 and 21 using Gutta Percha and Roths sealer. The core had been restored using a liner of Cavit (3M Espe) in the deeper layer, non-descript B1 flowable and B2 composite. Following the specific examination, diagnosis, treatment plan and informed consent, the patient was recalled on a second day for preparation and completion of two direct, layered complex composite resin veneers on 11 and 21. The patient was anaesthetized ( 1.5 carpules of 4% Articaine (amide anaesthetic) with 1:105 epinephrine, fig. 1).  Prior to split dam isolation (fig. 2), the colour map was immediately charted. It is noted that any given time, color assessment is a snapshot of the varying optical properties of the tooth in flux.  This assessment is influenced by dehydration, time/aging, and is depending on 5 variables: hue, chroma, translucency, fluorescence and opalescence.  Irfan Ahmad describes the color match at any given time is more ephemeral rather than eternal.1

A diode laser gingivectomy (Ezelase 940nm, Biolase, 1.5W continuous) was completed to remove overgrown tissue in the underhang shelf region subgingivally on the distoaxial surface as described previously (fig. 3). The use of the laser facilitated simultaneous tissue removal and hemostasis, producing ideal conditions for bonding and was selected because the 940nm wavelength is optimally absorbed by hemoglobin and oxyhemoglobin. The subgingival perforation and repair can be visualised in this photograph, along with the translucent composite used by the dentist in the previous core. It was decided that complete removal of existing composite would result in possibly more damage to residual tooth structure so the preparation was stopped at this point. Caries detector dye (Caries Detector, Kuraray) was utilized at this point to visualize and remove residual bacterial mass, ensuring a hard, clean dentin base.

Following dry #0 (Ultrapak, Ultradent) retraction cord placement via the continuous buccal sulcus packing technique, micro air abrasion was completed using  50 micron aluminum oxide for increased micromechanical retention (fig. 4).

Etching with 33% orthophosphoric acid was completed, followed by application of a 4th generation, 3-step total etch adhesive system (Optibond FL, Kerr).  

The initial layer was the lingual shelf, created for both 11 and 21 freehand   with the use of a Mylar matrix strip (fig. 5). The initial layer would have been more easily created with the use of a putty matrix fabricated from a diagnostic wax-up, however the patient chose to omit this step due to financial limitations. This initial layer is approximately 0.3mm thick, re-establishes the desired length and proportions of the tooth, and is fabricated from a milky-white translucent enamel shade. Amaris TN (translucent neutral) was the shade used for this scaffold.

The goal of the next layer was to start to mask out the translucent background as best as possible with opaque dentin shades. The opacity would be positioned in a way to block out the visibility of the join lines. Failure to do this would lead to a less-attractive final outcome. The limitation in this case was the thickness and translucency of the residual core due to past materials used.

Amaris O3 (Opaque #3) was used in the distoaxial region in the deeper layers to visualize whether this shade was adequate to match the stump shade of the tooth (fig. 6). After curing, it was decided that a slightly lighter opaque shade (Opaque #2) would be utilized in the superficial layers to best match the target value of the tooth (fig. 7). This mathematical modifiability of Amaris makes direct esthetic dentistry a breeze and a pleasure to do. This layer is also important because dentin creates the basic hue of the tooth and complements the fluorescence and chromatic interpretation of the final restoration.4

The superficial dentin layer was sculpted and burnished cervically in the marginal areas to occlude the buccal subgingival perforation region. The incisal half was created from a second increment of Amaris O2 and burnished incisally. This layer is characterized by irregular fingers of dentin which will form the basis of the incisal effects seen in the final product. Lobe formation of the dentin layer is also built into this superficial dentinal layer before final curing. The next layer involves a highly-translucent shade used in the incisal fingerling and dentinal lobe areas as a space filler. The use of a clear translucent shade increases the light penetration, transmission, reflection and refraction of this area in the finished result (fig. 8). 

The shade is now assessed with the dehydrated shade of the adjacent teeth.  It is an imperative that once the color map is decided on, that there is very little or no intra-operative modification. The lighter appearance of ever-dehydrating teeth is a great distractor, tricking many clinicians to create teeth that will stay too white after the adjacent dentition has rehydrated. In this case, the patient had requested slightly whiter teeth as he had wanted to complete vital tooth bleaching on the adjacent teeth sometime in the future. As central incisors are often a fraction lighter than the lateral incisors in nature, it was decided that we would place a lighter enamel shade (TL: translucent light) instead of our planned shade (TN: translucent neutral). Again, this mathematical modifiability of Amaris allows value control of the final product at different stages in the buildup.

There are two balls of cured Amaris composite placed on tooth 11 as an intra-operative shade guide: the more incisally-placed ball is TN (translucent neutral), and the more cervical ball is TL (translucent light). TL applied by itself in a thick layer would increase the value of the tooth beyond our target shade (fig. 9), so it is important to always judge the thickness and morphology of your dentin layers from the incisal aspect.1 In this case, a very thin layer of final enamel-shaded composite was all that was required to build the tooth emergence profile and line angles to full profile, and thus it was decided to use TL to slightly lift the value of the dentin layer (fig. 10).

Following final curing, contacts were opened using light interdental separating force (The “Mopper Pop”) and finished using moderate and fine abrasive metal strips (GC) as well as Epitex abrasive polymer strips (GC). Pencil markings were placed on the labial surface guiding preservation of line angles and emergence profile.  Primary and secondary anatomy finishing was completed using coarse abrasive discs (Soflex, 3M ESPE) and fine needle-shaped diamond grit burs (Mani Dia-Burs). Polishing was completed using the Double Diamond two-step (Clinician’s Choice) System at 5000 rpm to high shine, followed by final buffing using an aluminum oxide paste (Enamelize, Cosmedent) on a felt disc (Flexibuff, Cosmedent, fig. 11).  The patient was sent away for gingival healing and final composite set before recall and final polishing (fig. 12).

Rationale for Choice of Restorative Material

For the patient, a 16 year old young male with multiple structural coronal compromises in his upper central incisors, it was important to select a composite system with both superior physical properties and an advanced shading system which would be critical in recreating the optical nuances of nature. The goal in this case is biomimicry through restoration of original tooth volume, maverick effects and anatomy. 

Tooth reduction required in this case was minimal, perhaps 15-20% of total tooth volume. Residual tooth volume in this case was comprised of a tight intermingling between core material and irregular tooth structure. It was thought best not to disturb this matrix as there was no evidence of deeper caries and the high risk of reducing yet even more precious dentin structure. Pascal Magne advocates bonded porcelain restorations in cases where structural coronal compromise is greater than 60% of the original tooth volume. This figure represents the critical threshold of minimal crown stiffness needed for long-term performance where increased loss will require a material with heightened physical properties. A composite material is more flexible than porcelain and when used to regain stiffness in a critically-weakened tooth renders it still highly susceptible to fracture.3  

Tooth 21 in this case exhibited less than 40% residual tooth structure, and would have been a good candidate for a bonded porcelain restoration, if financial constraints were a non-issue. Esthetic symmetry would have been most predictable by also placing a bonded porcelain restoration on tooth 11, but again was not possible in this case. It was realized before we started that the residual stump shade would be different from if the teeth exhibited intact dentin, and thus the flexibility of being able to modify shading intra-operatively became invaluable. The solution then, was to use a modern super composite that not only ranked highly in physical properties, but also exhibited an intelligent shading concept, that would allow value modification on the go.  

This case utilized the achromatic enamel technique according to Newton Fahl.2 The case utilized a non-Vita-shade enamel layer (Amaris TN: translucent neutral) with the chroma being composed of two dentin shades (Amaris O3 and O2). In this case, the value of O3 was judged to be too low relative to our target value, and hence utilizing the Intellligent Shade Concept coined by VOCO, was able to be modified using a dentin shade of brighter value, O2. The value was modified further by the use of a higher-value enamel layer than initially proposed (Amaris TL: translucent light).  

Precision of incremental layer thickness is crucial to the development of the shade match. Too thick an enamel layer will create a result with lower value than intended. Too thick a dentin layer will affect value, hue and chroma.1 This was judged frequently and systematically from the incisal edge as volume was rebuilt.  

In this case, the preservation of residual intact dentin volume was key in our decision to leave the bulk of core structure intact. The use of an intelligent composite system that allows mathematical modifiability as core shade changes intra-operatively was crucial to the success of this case. The ability to recreate lost tooth volume, contours and optical nuances using a single system with the brains to help you through unexpected esthetic intra-operative hurdles really does make Amaris a modern super composite and a key instrument in the modern, conservative esthetic dentist’s arsenal. Featuring one of the most highly-polishable surfaces in combination with minimal surface roughness and 3-body abrasion features will provide this patient with a functional and ultra-esthetic result that lasts. Amaris is a formula:  a formula for predictability in difficult anterior esthetics as well as the simple equation that will keep our patients smiling long into the future. 
 
 

About the Author

Dr Clarence Tam maintains a private practice in Newmarket, Auckland (New Zealand), with a special focus on cosmetic and restorative dentistry. Born and raised in Canada, she is a graduate of the University of Western Ontario also having completed a General Practice Residency at the University of Toronto/Hospital for Sick Children. She is the Director and Chairperson of the New Zealand Academy of Cosmetic Dentistry.                            
Contact:
Dr. Clarence Tam, HBSc, DDS
Cosmetic and General Dentistry
Morrow Street Dental
18 Morrow Street
Newmarket, Auckland 1023
E-Mail: [email protected]
www.clarencetam.co.nz
 
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