Improving esthetics

March 21, 2012

Restorative treatment of the anterior dentition is still considered challenging, even with today’s innovative techniques and materials.1,2

Restorative treatment of the anterior dentition is still considered challenging, even with today’s innovative techniques and materials.1,2

Careful treatment planning and a multidisciplinary approach are of utmost importance when undertaking any restorative procedure in this region of the oral cavity because of the functional and esthetic requirements that are placed on these types of restorations.1,2 Seeking correction of their smile, many patients present with conditions of the anterior region, including chipped teeth, excessive wear, fractures, discoloration and, most commonly, diastemas.1,2

Diastemas typically develop between the central incisors.3,4 Caused by a variety of factors including transient malocclusion and developmental, pathological or iatrogenic factors, many treatments options are available.3,4 Composite build-ups, veneers, multiple crowns, orthodontics and surgery are beneficial in closing interdental spaces. However, in many cases these treatments do not provide the esthetics, longevity or strength desired, and patients have found these treatments burdensome.3,4

For example, orthodontics require the patient to undergo costly and extended treatments, while others like conventional crowns and veneers require significant reduction of otherwise healthy tooth structure.5 Surgery is a viable option but can be costly, time consuming and painful.5 Other treatment options, such as composite resin build-ups, offer a quick and minimally invasive way to close interdental spaces in the anterior, but are prone to discoloration, staining and failure over time.5

There are, however, newer materials on the market that have changed how diastema treatment is approached.6,7 One material, an innovative glass-ceramic, has been used to create a veneer, or shell, to close the space. Proven to withstand the functional requirements and esthetic demands of the anterior region, loss of natural tooth structure is minimal and excellent esthetic results are achievable.6,7

What it can do

An innovative all-ceramic material, lithium disilicate glass-ceramic (IPS e.max), offers optimal strength and esthetics when compared with traditional all-ceramic and supported-ceramic materials.8-10 Containing about 70% (by volume)needle-like crystals in a glassy matrix, the controlled size, shape and density of lithium disilicate’s unique structure allows for greater strength and durability, while demonstrating excellent optical properties, including life-like translucency.8,9

Available in two different processing techniques, lithium disilicate can be pressed using the lost-wax technique (IPS e.max Press) or milled with CAD/CAM technology (IPS e.max CAD).9-11 Although most material properties are similar, pressable lithium disilicate demonstrates a flexural strength of 400 MPa, compared with milled lithium disilicate, which has a flexural strength of 360 MPa.9-11

Because lithium disilicate is 2.5 to 3 times stronger than other glass-ceramic systems, it can be used for a variety of indications, including single-tooth restorations, thin veneers (0.3 mm), minimally invasive inlays and onlays (1.0 mm), partial and full crowns, three-unit anterior bridges and implant superstructures.10,12,13 With a variety of restorative and esthetic treatment options, dentists will find simplicity in seating lithium disilicate restorations because they may be adhesively bonded or conventionally cemented.9,14,15 Please note that for veneers, adhesive bonding is recommended. Additionally, lithium disilicate restorations may be fabricated into a framework that can be veneered or a full-contour restoration that can be characterized with ceramic stains and glazes.

Available in a variety of translucencies, including high translucency (HT), low translucency (LT), medium opacity (MO), and impulse ingots (Value, Opal), lithium disilicate CAD and Press (IPS e.max) restorations are ideal, even in the most challenging esthetic cases.

The case below demonstrates how a laboratory-fabricated pressable lithium disilicate crown (IPS e.max Press) was used to replace a crown on a patient’s central incisor, along with a thin (0.3 mm) pressable lithium disilicate veneer to close a diastema between tooth Nos. 8 and 9, following a minimally invasive treatment plan.

Case presentation

The patient, a 42-year-old woman, presented with previous restorative work and a diastema between tooth Nos. 8 and 9 (Fig. A). On tooth No. 9, there was an old crown that needed to be replaced, and the patient wanted the diastema to be closed-which called for a dramatic treatment plan. A new IPS e.max lithium disilicate crown was chosen for tooth No. 9, while a veneer was fabricated from lithium disilicate and placed on tooth No. 8 to close the diastema between the central incisors.

Traditionally, dentists have used composite build-ups or have fabricated two separate crowns to close diastemas.5 Composites, however, often lack the esthetics required in the anterior region, while placing two crowns leads to aggressive preparation and the unnecessary loss of otherwise healthy tooth structure.5 In comparison, using a veneer is non-invasive, and there is no need to touch tooth substructure. Adhesive cementation can remain in enamel, which creates the most secure and strongest bond, eliminating the need for preparation into the tooth structure.16

The patient’s dentition also underwent in-office bleaching, requiring a low-translucency shade (IPS e.max LT) on the restorations initially, with a bleach shade (IPS e.max BL1) the ultimate goal. When selecting shades, the proper ingot and calibration of material is of the utmost importance to develop the ideal translucency and to blend the ceramic material with the tooth structure-which leads to restorations that are indistinguishable from the patient’s natural dentition.17,18

Laboratory technique

After receiving all necessary case information from the dentist, including shade requirements, the case was ready to be pressed from lithium disilicate glass-ceramic (IPS e.max Press). Because the patient’s dentition was undergoing bleaching, the final desired shade of the veneer was B1. Therefore, IPS e.max Press LT B1 ingots were used. This is currently one of the only materials and techniques available that allows pressing of 0.3 mm restorations. Additionally, because of lithium disilicate’s optical properties and strength, the new crown for tooth No. 9 would demonstrate the esthetics required of dentition in the anterior region.

01 To begin fabrication of the veneer, the ideal wax-up was created according to the tooth distribution, and a matrix was formed from the wax-up model. The wax was then sprued, invested, burned-out, and pressed using a low translucency shade of lithium disilicate (IPS e.max LT).

02 After firing, the restorations were divested and placed in IPS e.max Press Invex Liquid to soften the surface reaction layer prior to blasting with alumina. The completed lithium disilicate veneer was cut from the sprues and scrutinized against the model. After finding the pressed filter acceptable, the restoration was ready for staining.

03 Initially, IPS e.max Ceram Essence stains were applied to create internal effects of the veneer similar to the ones found in the patient’s natural dentition. IPS e.max Ceram Glaze Paste (Fluo) was further applied to add fluoresce to the restoration, followed by firing.

04 Once fired, a natural and mechanical polish was completed using diamond paste and pumice to fully develop the desired surface texture of the veneer. The same procedure was then undertaken to create the crown for tooth No. 9.

05 Upon completion of the veneer and crown, the restorations were placed on the model to test fit and function (Figs. B, C and D). The restorations vastly improved esthetics by correcting the associated problems of the previous crown and the large diastema between the central incisors (Fig. E). The case was ready to be delivered to the dentist and patient for final cementation. 

06 The crown for tooth No. 9 was cemented first, followed by the lithium disilicate veneer on tooth No. 8 to close the diastema (Figs. F and G). After cementation, the completed restorations displayed excellent fit, function and esthetics-while achieving the ultimate goal of replacing the unesthetic crown and closing the large diastema (Figs. H and I). The patient was pleased with the results and has a smile she’s proud of (Fig. J).    

Conclusion

By using an innovative material and technique, the technician and dentist met the patient’s demands. By closing the diastema using a lithium disilicate veneer, we prevented the unnecessary loss of healthy tooth structure. Although challenging, restoring the anterior dentition can be completed through a multidisciplinary approach and careful treatment planning. The most rewarding of all dental treatments, functionally and esthetically pleasing anterior restorations allow patients to smile with confidence-many, for the first time.