Using IPS e.max® to Rebuild a Smile and Save Tooth Structure

By: Dr. Tony Hatch - Scripps Rock Dental

Dentistry in the anterior hasn't always been for the faint of heart. The added stresses of making the restoration disappear at the same time as assuring a proper fit, function and durability often times pushes such cases to the dental laboratory. In other cases extending the case to include additional teeth to help "hide" the needed dental restorations is employed. This further complicate the decision to treat. Do we recommend additional, irreversible restorations to assure a seamless smile to help obscure the new ceramic? Does the patient want to accept the added cost or do they fully understand that adding treatment will ultimately require its replacement down the road at the end of its functional life span? To help eliminate these difficult and challenging situations we need a strong armamentarium of products and skill sets. Ideally we would have a material that is strong, esthetic and have the control to assure it esthetically matches the first time.

Case Study - A 20 year old, female patient, arrives wants to replace the "bonding" on her front tooth. She had fractured # 8 approximately 8 years earlier. At that time a root canal was performed and a large resin was placed, the resin was replaced twice during the last 8 years. She reported that, "it was always too dark but got real bad after I did my Groupon whitening at collage". The root canal looked unremarkable on radiograph and tested WNL for percussion and palpation. The existing resin was markedly wider than #9. Her remaining anterior teeth were without decay or existing restorations. The patient liked her smile with the exception of the, "dark, wide tooth".

pre-treatment 1
Pre-Treatment 1

Pre-Treatment 2

We reviewed all her treatment options but I recommended a single crown and a single veneer on # 9 to balance the size discrepancy. Her case was challenging in that she had an unforgiving lip line, suspected dark stump shade, her young age and a beautiful #9.   Selecting the right laterals to handle these challenges was paramount to predictable success. IPS e.max was selected based on its strength and flexible beauty. I also untiled the CEREC Omincam to assure that I would have complete control. 8 was to be a full counter restoration over a large resin build-up, I was planning on a heavy prep to facilitate making the stump. 9 was to be a thin veneer to avoid all unnecessary reduction, my goal was a 0.3 to0.5mm thickness. Matching materials, even identical materials of such varying thickness, let alone over suspected differing stump added to the potential pitfalls.

Treatment Day - Traditional local anesthesia was obtained with 1 carpule of 4% Septocaine with EPI 1:100000. The patient was pre scanned with the CEREC Omincam and the Biogenic Biocopy was utilized as the design choice. Biocopy was selected because while the width of the teeth were disproportioned the overall length, inclination, line angle and embrasures were correct. If the inclinations or line angles had been too far off I would have either done a quick full contour composite mock-up or a prepared a diagnostic wax up to Biocopy. 8 was rough prepared and its stump shade finally evaluated, as suspected it was dark. On 9 depth cuts were employed, 5mm mid-facial feathered to 3mm at the gingival and incisal thirds. The mesial component of the prep was cared through the mesial facial line and into the contact area to allow for midline shifting. A majority of the preparation remained in enamel and no incisal reduction was done. At this point it was decided to further reduce and block out 8 to help balance the stump shades. Tetric EvoCeram, shade B1 was bonded and both preps were finished with super fine diamonds. "000" EPI cord was packed and the final preparations were scanned along with the lower anterior a buccal bite for digital occlusion verification.

Pre Prep Post Prep

 

Once the case was digitized within the CEREC software the midline was shifted mainintaing the identical inclinations and line angles and embrasures. Width was easily balanced using the in software grid tool. Slight facial contours were added on 8 to match 9. Additional material was added to the margins of 9 to allow the veneer to be milled without chipping. 8 was milled in normal mode and 9 was milled in Veneer mode. Veneer mode assures that no additional material will be removed to eliminate any potential undercuts. This does mean that if the veneer isn’t full seating an under was left and must be found and removed. This is an easy task and most often is done in the preparation, not the restoration.

The restorations were milled in IPS e.max BL3HT. Post milling the sprues are removed with a Super Max Heatless lab stone. The restorations were tied in to verify margin fit and interproximal contacts. The additional material material on the veneers margins are polished back with a Koolie wheel on a lab motor under magnification. This is done after milling to ensure that the margin are finished chip free. Contours on both were refined with a fine diamond and only select polishing was done on the convexities and across the incisal edge. A final minimal thickness of 0.3 was found on the veneer.   Crystaiztion was done initially with stain only, this allows for a greater contour of customization and greater visual perception of "depth" of the stains. A second try was done to assure shade matching was coming along and allow for the patients input. The restorations were fired gain with a glaze coat and additional white hypercalifications were added and warmth to the gingival fifth.

Thin .3mm
Thin .3mm Gauge

 

Bonding - After the second firing the restorations were tried in again to assure the gaze was not interfering with the fit. Occasionally, especially with anterior cases, glaze on a contact will throw of the fit and open a contact. Any excess glaze is polished back with a super fine diamond and fit assured. Variolink Esthetic was selected to bond both restorations. It is a light cure material and comes in 7 shades to facility Value changes. This differs from other anterior bonding systems that come in shades that modify Hue or Chroma. Here we have the "color" we want but maybe the restoration is too bright or dark. We used the included Try-in Pastes and evaluate several both in the chair and by a natural light source. It should be noted that if needed we could have selected different shades for each to help balance the values. The restorations were etched applied Monobond Plus then bonded into place using Variolink Esthetic DC - Neutral. Cement was fully removed and occlusion verified.

Post Smile
After Close

 

The patient as thrilled with the outcome. The case was conservative and limited to only what was required to balance the case. Due to IPS e.max strength value, 300+, and enamel bonding I expect many years of stress free, esthetes, success from the veneer. The crown conversely should also have an equal success rate based on its thickness and strength as well as its final marginal fit and traditional cohesive preparation.