Show Your Work: Dental Restorations — Building Better Bonds by Dr. Hemali Ajmera

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Show Your Work: Dental Restorations — Building Better Bonds  

Improving minimally invasive and aesthetic anterior dental restorations

by Dr. Hemali Ajmera

Extraordinary dental challenges require out-of-the-ordinary diagnostic methods. Aesthetic restoration of malformed, misshapen and underdeveloped lateral incisors can range from extraction with implant or bridge replacement, altering the proportions of adjacent dentition to create space for restorations, to orthodontic realignment before tooth alteration for restorative space.1 Based on your approach for preserving natural tooth structure and what the underlying tooth structure allows for, minimally invasive aesthetic enhancements can involve cosmetic bleaching, resin bonding, porcelain laminate veneers, metal ceramic restorations or all-ceramic restorations.2

The primary consideration should be conservation and minimally invasive restorative options. Assessment of the occlusion is necessary to determine if the lateral should be repositioned to allow for optimal aesthetics. Upon reviewing line angles, embrasures and positioning of the canine and central incisor, treatment planning can begin. In many cases, minimal orthodontic alignment to create a lingually displaced lateral incisor by just 3 degrees in relation to the adjacent dentition or a minor extrusion or intrusion movement can help manage facial clearance and gingival zeniths. Now, a minor bevel preparation on the facial for optimal restorative outcomes is possible without removing tooth structure to dentin on an already small tooth. Based on the defect, alignment can be performed before or after permanent restorative dentistry.3

Smile design principles have found that narrow lateral incisors are considered unaesthetic; meanwhile, the overall perception of the maxillary lateral incisor length is in agreement with the long-established 1–1.5mm shorter lateral incisor with respect to the adjacent central incisor and canine along with a wider lateral incisor. We know now that the golden proportion is a range, not a single value, and that gender doesn’t affect these aesthetics. Because of this subjectivity and range of proportional acceptability, it is worthwhile to discuss if lengthening a lateral incisor will suffice to create the preferred aesthetic result before treatment of adjacent dentition or orthodontic movements to create increased width.4

Stronger products like zirconia that must bear occlusal forces have an opacity for which they have undergone various transformations in their composition to provide improved translucency, which in turn has compromised their strength. So decision-making on minimally invasive restorations requires optimal strength for bonding on enamel and dentin when it comes to ultrathin restorations and preparation techniques. Similarly, some multilayered restorations are prone to chipping or delamination because they must rely on the resin bonds that can weaken and fracture over time, so exploring other restorative options becomes necessary.5

Improved imaging

Near-infrared imaging (NIRI) is a nonionizing radiation method of spectroscopy that uses the near-infrared region of the electromagnetic spectrum (850nm), so the structure’s translucency translates to the brightness level in the NIRI image. Tooth enamel is translucent to NIRI, so it appears dark, while dentin or any other interference in the enamel displays as reflective and will appear brighter and opaque.

The resulting NIRI grayscale image shows structures with varying translucency as different levels of brightness, allowing us to use it as an adjunct to determine if direct resin bonding results will be allowable on healthy tooth structure with minimal beveling, or if more preparation is required with a lab-manufactured restoration. The lower the translucency, the higher the reflection of the infrared light and the brighter the structure. Because dentin appears bright and enamel dark, we can have another adjunct to our cosmetic dentistry toolbox. In cases where the enamel darkness at the incisal edge is minimal, the buildup of resin bonding can be deemed successful if proper proportions can be established. NIRI allows us to compare the enamel thickness of the central incisor and the canine in reference to the lateral. We can then make predictable decisions on preparation styles and perform minimally invasive cosmetic enhancements.6

By providing 3D images, NIRI can deliver useful operating suggestions, enabling a targeted cavitation into the dental crown and the ability to reach small caries with precision and good restorative results in a less invasive manner. Because of their two-dimensional nature, radiography and photography are valuable but cannot be the sole reliance for proper diagnosis and treatment planning.7 NIRI has considerable potential for imaging early approximal enamel lesions.8

Better bonding

An indirect technique with a die silicone and minimal tooth preparation to create an additive partial veneer is cost-effective and allows for aesthetic control and a strong bond to the existing tooth enamel for a same-day, chairside result.9 A pure silicate matrix technology combined with nanohybrid fillers, creates a nano-ormocer without classic methacrylate monomers, allowing for large and precondensed inorganic polymer molecules that photo-polymerize with reduced shrinkage, minimizing microshrinkage.10

Futurabond U, a bonding agent, allows us to pre-etch the beveled enamel. It also provides an added level of adhesion strength with its two-component system that is activated when mixed and applied for a 30 MPa bond to enamel and dentin.11 Dental calipers measure proportions and make assessments on treatment, with or without orthodontics, to achieve a close-to-ideal golden proportion ratio for improved aesthetic outcomes. In this case (Fig. 1), we see that length and width of existing anterior dentition allow for great restorative outcomes.12

Show Your Work: Dental Restorations — Building Better Bonds
Fig. 1

Case report

A 21-year-old patient presented to the office in need of a cleaning and smile improvement. The lateral incisors were short and required elongation to improve the final aesthetic outcome. She was interested in a painless treatment option that will allow for alignment and whitening in the future.

Photography (Shofu Eye Special III) with retraction using OptraGate (Ivoclar Vivadent) and immediate shade taking (Vita Easyshade) resulted in shade 2M1. Caliper use showed #7 and #10 as 6mm wide and #8 and #9 as 8.5mm wide with nice symmetry (Fig. 2). A scan was performed (iTero Element5D) along with preoperative photography to assess the ability to bond in a minimally invasive manner. The scan shows minimal characterization on the incisal edges of the lateral incisors and light occlusal contacts, allowing for a chairside additive bonding procedure with an enamel bevel (Figs. 3–6).
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 2

Show Your Work: Dental Restorations — Building Better Bonds
Fig. 3
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 4
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 5
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 6

A preoperative alginate impression was taken and filled with die silicone material (Voco), allowing for a four-minute set time (Fig. 7). Creation of the lingual, incisal and facial surfaces of the veneer was achieved by building up small lobes of Voco Admira Fusion X-tra and light-cured with the Voco Celalux 3 curing light (Fig. 8).

Show Your Work: Dental Restorations — Building Better Bonds
Fig. 7
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 8

Tooth preparation was done with a coarse disc (3M) to create a light bevel on the incisal one-third of the tooth.13 The tooth was prepared for bonding with irrigation using a three-second chlorhexidine rinse and biofilm removal with Bioclear Air Abrasion with aluminum trioxide. After this, a selective etch technique was performed, etching the enamel ring for 15 seconds with 40% phosphoric acid etchant (Henry Schein) with a thorough rinsing protocol. After this, Futurabond U primer/adhesive (Voco) was brushed in two coats over 20 seconds on all surfaces, thinned with a gentle stream of air, and light-cured for 35 seconds (Figs. 9–10). Admira Fusion X-base (Voco) was applied on the inner surface of the partial veneer and seated on the tooth. After excess material was removed, all surfaces were light-cured (Fig. 11). A final light cure was done after DeOx (Ultradent) application, allowing for polish and adjustments using coarse finishers (Shofu) and Dimanto polishers (Voco, Fig. 12).

Show Your Work: Dental Restorations — Building Better Bonds
Fig. 9
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 10
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 11
Show Your Work: Dental Restorations — Building Better Bonds
Fig. 12

The final result allows this patient to smile and enjoy further enhancements like teeth bleaching without concern for overly bonded anterior dentition (Fig. 13).

Show Your Work: Dental Restorations — Building Better Bonds
Fig. 13

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Author Bio
Hemali Ajmera Hemali Ajmera, DDS, FACD, practices general dentistry at Ajmera Dental Studio with a focus on cosmetic dentistry and comprehensive care. She is a graduate of the seven-year accelerated BA–DDS program at New York University College of Dentistry and a member of Catapult Education and the American Dental Association. She gives back to the community by creating platforms for education and by partaking in philanthropic causes in her previous role as past new dentist chairwoman of the New York State Dental Association and now as a fellow of the American College of Dentists.
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