Written by Galip Gürel, DDS Thursday, 09 May 2013 13:10
As new dental technologies emerge, the dentist’s ability to meet patient expectations while maintaining functionality has been redefined. The use of diagnostic tools, effective communication, and the aesthetic pre-evaluative temporary (APT) technique enables every dental clinician to achieve highly aesthetic results while surpassing patient expectation and preserving tooth structure.1-3
Erosion and attrition cause thinning of enamel. This reduction of tooth structure leads to increased crown flexibility and surface strain.4 Ideally, the dentist is able to mimic the biomechanics of an intact tooth with restorative procedures. Adhesively bonding a porcelain veneer to the tooth enables the stress caused by occlusal and masticatory forces to be disseminated throughout the entire crown, thus minimizing the effect thinning enamel has on tooth strength.4,5
The success rate of porcelain veneers is well documented, especially in cases where the restoration has been adhesively bonded to enamel.6 Tooth preparation design is a significant factor in determining the longevity of the restoration. Minimal or no preparation in cases where thinning enamel exists is recommended for placement of porcelain veneers6 to preserve the maximum amount of enamel. Gürel et al1 recently showed a 98.7% success rate of porcelain laminate veneers (PLVs) when the preparation depth is kept within the limits of enamel.
The following clinical case report will demonstrate a 3-step approach to advanced design that, when followed, can consistently create predictable and desirable aesthetic outcomes.
Diagnosis and Treatment Planning
A female patient presented with the chief complaint of a compromised aesthetic smile (Figures 1a to 1c). The patient complained of short and dark-colored anterior teeth. She desired to have these teeth restored to their natural appearance, which she enjoyed about 10 years previously. Additionally, the patient suffered from tooth sensitivity due to cervical erosion.
Clinical examination of the maxillary anterior teeth revealed significant erosion and attrition with thin enamel surface (Figures 2a to 2d). Other findings included a failed restoration on tooth No. 12, full coverage crowns on teeth Nos. 13 and 14, and a 3-unit bridge on teeth Nos. 3 to 5. The patient showed no discomfort during function and no sound during opening and closing during examination of the temporomandibular joint. The medical history revealed no significant findings and no known drug allergies.
|Figures 1a to 1c. Preoperative full-face photos.|
|Figures 2a to 2d. Preoperative photos showing severe erosion and attrition.|
Step One: Patient Communication and Mock-up—Initial communication with the patient, both verbally and with models, is extremely important. This communication allows both clinician and patient to share their expectations, further eliminating patient dissatisfaction at the end of the procedure. Verbal communication alone is never enough.7,8
Technological advances like computer software imaging allow the patient to visualize smile design and final outcome. While these advances provide useful visual references, clinically delivering the computer-generated design is not always practical. However, an intraoral mock-up allows both the dentist and the patient to inspect a 3-dimensional (3-D) depiction of the shape; form and contour of the initial design; and its effects on upper lip posture, smile-line relation with the lower lip-line and phonetics.
In today’s world of dental aesthetics, it is almost impossible to assess the final structural and aesthetic result without a mock-up, especially from the patient’s point of view. This procedure requires a precise knowledge of the tooth anatomy along with intuition, sensitivity, and a good perception of the patient’s individual personality.
A mock-up assumes even greater importance when PLVs are being designed because of their relative thinness and the need for a conservative preparation approach and because the tooth preparation will be determined directly by the position and volume of the definitive restoration. Also, during the buildup of the mock-up, the more additive the approach is, the more minimally invasive it will be.
The position of the incisal edge acts as the parameter upon which the rest of the design is built. Elongation of the incisal edge is often indicated to correct incisal wear, inadequate tooth display, or a displeasing tooth or crown proportion. Once it is set, the incisal edge serves to determine the proper tooth proportion and gingival level, making it especially important. Several teeth should serve as the reference line for the correct incisal edge position of the treated teeth. However, the incisal edge of the maxillary central incisor is the first determinant in the creation of the new smile design.
Determining the incisal edge position is critical because it will affect the whole design and proportion of the mock-up in 3 dimensions, and therefore it must be verified both vertically and horizontally. For that reason, the author prefers to build up the 2 centrals first, sit the patient upright, make the final detailed adjustments on these 2 maxillary central incisors, and after light-curing continues with the 2 laterals, followed by the canines, and then the premolars (if they are to be included to the smile design).
In this clinical case, a mock-up was created by applying a veneer of composite resin (Tetric EvoCeram [Ivoclar Vivadent]) directly onto the tooth surface without any adhesive system. The desired tooth form was aesthetically designed and then light-cured (Bluephase G2 [Ivoclar Vivadent]). This procedure was then repeated until all of the teeth being restored had been designed. The entire mock-up was prepared to show incisal length, facial volume, overall effect with facial profile/smile of patient, and, to verify proper occlusion (Figures 3a to 3c).
|Figures 3a to 3c. Without an adhesive bonding agent, a dental composite (a) is placed free handed, molded in the shape of incisors, and light-cured (b). Figure 3c is the complete functional mock-up showing incisal length, facial volume, and the overall effect with facial profile/smile of patient.|
After mock-up completion, the smile design was discussed with the patient and adjustments were made based upon the patient’s expectations. The formation of a mock-up provided the advantage of allowing the clinician to communicate with the patient regarding the final aesthetic outcome and make adjustments prior to any irreversible procedures were performed.7 Once the smile design has been agreed upon, an impression of the dentition with the mock-up is taken. This impression will guide the ceramist during formation of the wax-up, or addition of wax onto the preliminary model.
It is very difficult to get advanced aesthetic results if the clinical case is not documented at each step with digital photography. An impression sent to the laboratory without demographical data, design parameters, or additional information becomes just another model on the bench. Sending intraoral and extraoral photo documentation, both still and video, allows the ceramist to comprehend the final aesthetic design. In cases where the patient is camera shy, adding a simple HD Handycam armamentarium (Sony) to the operatory allows the clinician to capture the patient’s smile. Post mock-up video allows the dentist to observe how the mock-up design impacts the patient. By sharing this video with your dental laboratory, the ceramist can gather more information about the aesthetic design and can produce a more accurate wax-up. Additionally, video recording also provides the ability to document a patient’s expectations, in his/her own words. If, at the end of treatment, the patient said, “No, I didn’t want this!” a record of the patient’s desires exists.
At this stage, the patient information was delivered to the laboratory. The laboratory was provided an impression and model of existing dentition, an impression of the mock-up to guide the ceramist for wax-up, impression, and model of lower dentition for articulation, and photo-documentation along with digital video recording for smile relation (Figure 4). Using these tools, the ceramist was able to fabricate a laboratory wax-up of the restorations following the exact guidelines that were provided (Figure 5).
|Figure 4. Extraoral photo after mock-up, checking the aesthetic outcome and the position of the incisal edges, relative to the interpupillary line.|
|Figures 5a to 5d. The wax-up, as prepared by the dental laboratory team.|
Step Two: Aesthetic Pre-Evaluative Temporary (APT) Technique—Traditionally, the teeth would be prepared and a silicone index used for the fabrication of the provisional restorations. This meant that the final restorative design would not be seen by the patient until after the provisional restoration had been made. This often resulted in one of 2 problems. The first problem was that the patient was unhappy with the aesthetic outcome of the provisional restorations. Since the teeth had already been prepared, altering the restorative design could not be easily accomplished. Oftentimes the patient liked the final outcome but the prepared tooth structure was exposed at one or more parts of the provisional restorations. This indicated that the tooth was underprepared, which was then compensated by an overcontoured thicker veneer or by repreparing the tooth. In both cases, predictability of the final design could not be determined until after permanent tooth structure had been lost.9
In order to overcome the above-mentioned limitations, advanced design techniques were developed to evaluate the final aesthetic design, prior to tooth preparation. The author conceived the idea of using provisionals in 2 additional clinical steps: during final temporization and before treatment planning was completed. This concept was introduced as the APT technique, and it has proven to be extremely beneficial for addressing key factors before treatment has been initiated and, most importantly, for ensuring minimally invasive tooth preparation.1-3,9
Therefore, one predictable and easy to use technique is to utilize the silicone index for fabrication of APT restorations.1-3,9
The 3 main advantages of the APT technique include predictable aesthetics, proper occlusion, and phonetics. The APT technique allows the patient and clinician to predict the aesthetic outcome, alleviating patient concern. Additionally, the design can be adjusted, and any limits on design choice due to functionality can also be addressed. Verification of occlusion of the new design can be checked with the existing occlusion in terms of centric occlusion, canine guidance, and anterior guidance. Because the APT represents the final outcome, phonetics can also be evaluated in advance. This is an advantage not often considered but extremely valuable.1-3
Once the wax-up was received from the dental laboratory, putty silicone impression material (Virtual Putty [Ivoclar Vivadent]) was placed over the wax-up to create a silicone index. The silicone index was used to determine the facial contour and incisal edge positioning of the final restorations (Figures 6a to 6e). Afterward, provisional material (Systemp C&B [Ivoclar Vivadent]) was injected into the silicone index and seated on patient’s dentition. Once the material had set, the silicone index was removed from patient’s mouth (Figures 7a and 7b). This newly formed APT (Figures 8a to 8c) provided a 3-D evaluation guide for the final restoration.
|Figures 6a to 6e. Silicone index prepared from laboratory wax-up. Silicone indices were used as guidance for facial contour, incisal edge position; and also used in fabrication of provisional restorations.|
|Figures 7a to 7b. Injecting provisional material in silicone index; then seating it over patent’s dentition for the fabrication of aesthetic pre-evaluative temporaries (APT).|
|Figures 8a to 8c. Aesthetic pre-evaluative temporaries. Note that of this moment the patient has not been anesthetized yet.|
|Figures 9a to 9b. Evaluation of APT from 12 o’clock position (a) to evaluate ideal arch position (b).|
In cases in which one or more of the teeth are positioned facially or palatally, evaluation of the APT from the 12 o’clock position is critical (Figures 9a and 9b). By placing the silicon index over the APT (Figure 10), the clinician can confirm that the APT is correctly placed within the oral cavity. At this point, due to the placement of the APT, it is possible to see the smile design (Figure 11).
It is important to note that if no adjustments have been made, the laboratory can use the first wax-up as a guide in the fabrication of the final porcelain veneers. However, if any adjustments have been made, new impressions will be required to send to the dental laboratory.
Step Three: Tooth Preparation—As discussed earlier, it is very important to prepare teeth precisely with minimal invasion for the clinical success of aesthetic restorations. Tooth preparation strategies are driven by either the existing tooth surface (mostly guesswork, which will not work precisely even in the hands of a very experienced dentist) or by the final volume of the restoration.2 If the APT is removed prior to tooth preparation, initial guidance will be lost and tooth structure will be compromised.1 Therefore, in order to be minimally invasive and precise, tooth preparation was achieved through APT. In this scenario, APT was defined as the final facial aesthetic contours and used as a guide with help of depth cutter burs. Depth cutters were used in 3 different angulations to achieve the accurate depth allowed by noncutting shaft (Figures 12a to 12d).
|Figure 10. Placement of silicone index to verify correct placement of APT in patient’s mouth.|
|Figure 11. Smile design with APT.|
|Figures 12a to 12d. Tooth preparation through the APT, using depth cutter at 3 different angulations to achieve accurate depth.|
It is important to note that in areas where the APT is thin, preparation of tooth structure will occur. However, in areas where APT is thick, the tooth will not be prepared. This allows clinician to prepare the tooth accurately and precisely with minimal invasion. If the tooth had been prepared without the APT, some preparation of the enamel would have been done when not necessary. The thickness of the depth cutter is directly sized with the thickness (or thinness) of the final porcelain laminate veneer. This thickness is dependent upon the color modifications between the stump shade and final restoration. For example, if the minimum average thickness of the porcelain laminate veneer is predicted to be 0.3 mm, then in cases where there is no or minimal color change only 0.3 mm thickness of tooth preparation is required. Thus, the width of the depth cutter should be 0.3 mm plus another 0.15 to 0.20 mm for added color modification. This variation depends upon the color blockout skills of the ceramist as well as the nature of the materials used for restoration fabrication.
Once the depth of the cutters was chosen (0.5 mm in this case), horizontal depth cuts were made with the APT in position. Pencil markings were used to pinpoint the depths created by depth cutters. A tapered diamond chamfer bur (5856.314.018 [Komet USA]) was used to create incisal reductions of approximately 1.5 to 2 mm, creating a 90° butt joint. This reduction provides enough space for the ceramist to add incisal anatomical features bringing a natural, life-like appearance to the final porcelain veneer (Figures 13a to 13c). In this clinical case, minimum tooth reduction was required at the incisal one third of the central incisors. Similarly, minimal amount of total tooth reduction was required on lateral incisors and canines (Figures 14a and 14b). Once the APT was removed, these pencil marks were used as a depth guide. Afterward, the facial surface of the tooth structure was prepared with a round-ended tapered fine diamond chamfer bur (8856.314.016 [Komet USA]). When the pencil mark disappeared, tooth preparation ceased.
Once the tooth preparation was completed, a silicone index created from the laboratory wax-up was placed over the prepared teeth to check the depths created. Because the index was so precise, the silicone index always provided an exact reading of the space provided as a result of the tooth preparation.
|Figures 13a to 13c. Horizontal cuts were made on APT with depth cutters (a); pencil was used to pinpoint the depth created by depth cutter (b); incisal reduction on APT (c).|
|Figures 14a and 14b. Pencil marks on tooth structure after removal of APT, which was used as a depth guide for tooth preparation (a). Teeth after preparation (b). Note extremely minimal tooth preps.|
|Figures 15a and 15b. Selection of stump shades; final veneer shades selected by patient.|
|Figure 16. Postoperative result.|
|Figure 17. Protocol for predictable aesthetic success for porcelain laminate veneers and crowns.|
Finally, the stump shade and desired final shade were selected (Figures 15a and 15b). These shades along with digital photographs were sent to the laboratory for fabrication of the final restorations. Lithium disilicate porcelain veneers (IPS e.max [Ivoclar Vivadent]) were adhesively bonded in place (ExciTE adhesive; Variolink II cement [Ivoclar Vivadent]) (Figure 16).
The key to predictable clinical success in aesthetic dentistry is advance design and planning. Advance design reduces total procedure time and provides a predictable outcome, taking into account the incisal edge, form, and shape to fit the patient’s aesthetic needs. Consistently following key steps (Figure 17) will ensure that both the clinician and patient are satisfied with the final restoration, while avoiding potential problems throughout the procedure. More importantly, when the APT technique is used, not only to assess the final aesthetic outcome but also for teeth preparation, truly minimally invasive preparations can be achieved.
The author wishes to thank to the ceramist, Hilal Kuday, for the outstanding restorations created for our patient.
- Gürel G, Morimoto S, Calamita MA, et al. Clinical performance of porcelain laminate veneers: outcomes of the aesthetic pre-evaluative temporary (APT) technique. Int J Periodontics Restorative Dent. 2012;32:625-635.
- Magne P, Belser UC. Novel porcelain laminate preparation approach driven by a diagnostic mock‐up. J Esthet Restor Dent. 2004;16:7-16.
- Gürel G. The Science and Art of Porcelain Laminate Veneers. Chicago, IL: Quintessence Publishing; 2003.
- Magne P, Douglas WH. Additive contour of porcelain veneers: a key element in enamel preservation, adhesion, and esthetics for aging dentition. J Adhes Dent. 1999;1:81-92.
- Kraus BS, Jordan RE, Abrams L. Dental Anatomy and Occlusion: A Study of the Masticatory System. Baltimore, MD: Williams & Wilkins; 1969.
- Peumans M, Van Meerbeek B, Lambrechts P, et al. Porcelain veneers: a review of the literature. J Dent. 2000;28:163-177.
- Ferencz J, Fanetti P. Enhanced Communication: An open dialogue between the dentist and ceramist offered this patient an esthetic and functional solution to teeth discolored by bonded orthodontia. Inside Dental Technology. 2011;2:44-50.
- Reshad M, Cascione D, Kim T. Anterior provisional restorations used to determine form, function, and esthetics for complex restorative situations, using all‐ceramic restorative systems. J Esthet Restor Dent. 2010;22:7-16.
- Magne M, Magne P, Cascione D, Munck I. Optimized Laboratory Provisional Restorations using the Sandwich technique. Dental Dialogue. 2006;6:68-77.
Disclosure: Dr. Gürel lectures for Ivoclar Vivadent and Sirona Dental Systems.
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