Rafael Santrich

When creating restorations using pressable ceramics with the cut-back and layering technique, dental laboratory ceramists have traditionally cut-back and layered the buccal aspect of the restoration.

After a fully anatomical wax-up is pressed, the buccal surface of the restoration is cut-back and contoured with a rotary instrument to make room to apply successive layers of esthetic and effects ceramic restorative materials. While properly supporting soft tissue response, this step-by-step technique is used to deliver predictable and esthetically precise restorations with the patient’s desired shade and simulation of internal nuances of the teeth, resulting in seamlessly natural-looking dentition.

In certain situations, however, cases present for which it’s beneficial to cut-back and layer from the lingual. This requires the laboratory ceramist to know which ingot will be best for the case combined with Impulse effects and Essence stains to achieve the desired final shade match.

Ideal for pressing all-ceramic restorations intended for cut-back and layering techniques, Ivoclar Vivadent’s IPS e.max Press offers optimal strength and esthetics compared to traditional all-ceramic materials while demonstrating excellent optical properties, including life-like translucency.

 Containing approximately 70% by volume needle-like crystals in a glassy matrix, the controlled size, shape and density of lithium disilicate’s structure allows for greater strength and durability.

 Lithium disilicate can be pressed using the lost wax technique (IPS e.max Press). Pressable lithium disilicate demonstrates a flexural strength of 400 MPa.

 Lithium disilicate restorations may be fabricated into a framework that can be veneered or, as in this particular case, a full-contour restoration that can be cut-back and characterized with ceramic stains and glazes.

Available in a variety of translucencies and opacities, including high translucency (HT), low translucency (LT)-both available in 16 A-D and 4 BL Shades-medium opacity (MO), high opacity (HO) and Impulse ingots available in three Value (V) and two Opal (O) shades, IPS e.max Press has a suitable ingot available for every patient situation, even the most challenging esthetic 

A 47-year-old woman presented with concerns about her maxillary central incisor 

. During consultation, it was decided that tooth No. 8 would be restored with an IPS e.max Press all-ceramic full crown. Prior to restorative procedures, the patient agreed to undergo whitening of the dentition to ensure a uniform, esthetic shade for the final result 

. The teeth then were prepared according to manufacturer’s instructions for IPS e.max Press lithium disilicate glass-ceramic crowns. A final tooth shade was taken and determined to be 2M1.

When selecting shades, choosing the appropriate ingot and proper calibration of material to develop the desired translucency and blend the ceramic material with the tooth structure is essential. This leads to uniform restorations that are indistinguishable from the patient’s natural dentition.

  Having reviewed the final shade, the dental technician decided on an IPS e.max Press Impulse V1 pressable ingot.

 After receiving all necessary case information from the dentist, including shade requirements, the case was ready to be pressed from an IPS e.max Press lithium disilicate glass-ceramic, currently the only material and technique available that allows pressing of 0.3 mm of material, making it the material of choice. Because of the optical properties and strength of lithium disilicate, the crown for tooth No. 8 would demonstrate the function and esthetics required of dentition in the anterior region.

 The ideal wax-up was created to full contour on a solid model, and a matrix was then created. The incisal edges of tooth No. 8 were shaped in the wax-up and matrix to perfectly match the incisal edges of tooth No. 9.

 The wax-up was then sprued, invested, burned-out and pressed using a V1 shade of IPS e.max. The material was chosen instead of traditional all-ceramic materials because of its exceptional quality of translucency, strength and durability.

 After pressing, the sprues were removed and the restoration divested and placed in e.max Press Invex Liquid and blasted to eliminate the surface reaction layer. The restoration was then fit to the model and ready for cut-back, layering and staining 

 The cut-back was performed by systematically grinding the lingual incisal edge 

. The translucency of the ingot, which is very important when matching the enamel with the ingot, rather than the ceramic is illustrated in 

 Essence stains were applied on the lingual to create internal effects similar to the patient’s natural dentition 

. The primary importance of the lingual cut-back technique is producing the internal, optical effects and exemplary esthetic properties of the final restoration. The lithium disilicate crown was then fired at 770°C 

 The result was examined and Opal Effect (OE1) was applied to cover the palatal incisal edge 

.Opal Effect (OE1) was applied to compensate for shrinkage of the palatal porcelain application 

. As a final step, the crown was baked at 750°C.

 After the bake, a natural and mechanical polish was completed using diamond paste and pumice to fully develop the desired surface texture of the full-contour crown. Once the restoration was completed, it was placed on the model to test fit and function. The case was then ready to be delivered to the dentist and patient for final cementation 

Creating a naturally translucent restoration requires a blend of science and artistry as well as time, patience and skill. Restorations need to be both technically correct and esthetically pleasing. Natural teeth possess nuances of shade and gradations of color, and dentition varies from person to person.

Each case must be assessed on its own merit. When creating a restoration indistinguishable from that of the patient’s natural dentition, conventional procedures may not always deliver optimal results. For instance, in cases that require a reduction in opacity and creation of a suitable incisal translucency, the lingual cut-back may be implemented to provide the opportunity to recreate the esthetics of the adjacent teeth.

Rafael Santrich, of VM Lab Technologies in Aventura, Fla., specializes in all fixed restorations and custom cosmetics. He has been featured in several publications such as “Soft Tissue and Esthetic Consideration in Implant Therapy” written by Dr. Anthony Sclar and on the ITI in 2009. He is currently a member of the American College of Prosthodontics.

Articles

Recreating patient’s translucency

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

	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.

 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.

	Diastemas typically develop between the central incisors.

 Caused by a variety of factors including transient malocclusion and developmental, pathological or iatrogenic factors, many treatments options are available.

 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.

	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.

 Surgery is a viable option but can be costly, time consuming and painful.

 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.

	There are, however, newer materials on the market that have changed how diastema treatment is approached.

 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.

	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.

 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.

	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).

 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.

	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.

 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.

 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.

	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.

 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.

 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.

	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.

	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).    

	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.

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