15: Direct Veneers

Chapter 15 Direct Veneers

Section A Direct Composite Bonding

Emanuel Layliev, Jeff Golub-Evans

Brief History of the Development and Evolution of the Direct Composite Bonding Procedure

The procedure for direct composite bonding has undergone an incredible evolution, along with an upgrade in materials that help create proper esthetic anatomy, characterization, hue, value, chroma, position, form, function, direction, and texture. It is now possible to improve a patient’s look predictably.

In the late 1970s macrofill composites were not very polishable, so dentists could not achieve as much of a shine as is possible today. These resins gave way to two classes of materials in the middle 1980s: the microfills, hybrid microfills and nanofills. The microfills are extremely polishable but stain over time. The nanofills did not evolve into successful products until after the 1990s.

In the 1990s, hybrids came into a fairly common use. These combine larger and smaller particles to fill the spaces between the resin filler material. With less resin material, there is less stainability. The hybrids are harder resulting from longer lasting surfaces.

Around the turn of the century, the nanohybrids were introduced. Extremely tiny particles fill in even smaller spaces and eliminate much of the resinous material. This makes the material stronger, more polishable, and less likely to stain. Today bonding is done with nanohybrids, sometimes including a very thin surface layer of microfills for even greater polishability.

Relating Anterior Function and Esthetics

The typical reason a patient requires the placement of direct composites in the anterior include normal wear and tear, occlusal disturbances, aggressive tooth brushing, or eating too much crunchy food. To create the proper look cosmetically, it must first be determined what has made such treatment necessary. It is important to evaluate the patient’s habits and normal function. This will reveal occlusal problems, perhaps abrasion, nutritional problems, erosion, or bruxism. The wear is evaluated to identify its cause, and then treatment possibilities and precautions are planned (Box 15-1). The goal is to avoid such wear in the future or at least minimize the threat of repetition. This involves evaluating what has happened to the individual’s teeth, and to the opposing dentition (e.g., the lower arch) to ensure that a better profile, shape, and position can be created for those teeth. Various modalities such as Invisalign (Align Technology, Inc., San Jose, California), bonding, or enameloplasty may be employed.

If the esthetic evaluation indicates that it is desirable to extend the patient’s central incisors by 2 mm in length incisally, it must be assessed whether this is possible. The outcome depends on functional, protrusive excursive, and lateral excursive movements. It may also be necessary to extend the coverage of the composite onto the tooth more to the lingual surface to create a stronger restoration, a night guard, and to evaluate the condition of the posterior teeth to rearrange the vertical dimension so it is possible to build up the anterior segment by 2 mm. This generally involves opening the bite in the posterior region by less than 2 mm.

To summarize, first evaluate the functional situation for both previous and current problems and then keep those situations in mind when planning treatment. Functional treatment planning is an essential part of the esthetic program. If esthetics and function are not addressed together, the case will fail.

Clinical Considerations

Material Options

It is the author’s recommendation to use a 37% phosphoric acid−etch with a light-cured adhesive (fifth generation), specifically, OptiBond Solo (Kerr Corporation, Orange, California). Composite materials used for veneering include hybrid Point 4 (Kerr Corporation) available in various shades, including opaques. As a final layer, Herculite (Kerr Corporation) Enamel Light or Extra Light is placed. Obviously the material of choice depends on whether the adjacent and other teeth are light enough to match. The color is built up in a microhybrid used below a microfill. The actual color of the dentin is placed over that. At times translucency is required. Vitalescence (Ultradent Products, South Jordan, Utah) and Trans Smoke or Iridescent Blue shade are excellent.

Innovative Elements

Artistic Elements

It is necessary to evaluate the impact of bonding on the face, not just on the actual appearance of the teeth. The entire face must be considered. This includes analyzing the shape of the lips and cheeks.

In analyzing the look of the face, it can be measured or visualized. For example, a patient may have a round or oval face. The treatment choice depends on what the patient wants. If the teeth look too flat and make the face look too round, the dentist can solve the problem by making the teeth appear a bit longer. If the patient’s face is too oval, the dentist can shorten the length of the teeth. If it appears that there is too much negative space at the buccal corridor in the posterior, the dentist can refurbish the smile by adding more tooth structure, thus plumping out the arch and creating a fuller, more youthful appearance.

Translucency, Opacity, and Fluorescence

Tooth structure is also translucent, a quality that must be matched in the restoration. Normally enamel is not completely transparent but translucent to a degree. To recreate that look requires various staining composites. Translucency is usually more pronounced in the incisal thirds of teeth.

To create translucency, the violet, blue, and red are added as appropriate. For female patients a blue hue is used; for male patients a more violet color is chosen. The enamel layer (or microfill) is placed over the translucent characterization.

Opacity originates in the dentin. It is seen throughout the entire tooth structure, mostly at the gingival third and mid-third, but is less apparent interproximally. As one approaches the incisal segment, the teeth are translucent rather than opaque. In building up a chipped tooth, the internal dimension requires a more opaque layer.

Fluorescence is defined as the look of the teeth under a “black” or ultraviolet light. Natural teeth sparkle white, unnaturally so, under a black light. The dentist must use composites that have fluorescence built in to recreate this. Otherwise, anterior veneers built up with a nonfluorescent composite disappear under black light conditions. It seems that the individual’s teeth are missing, which is not esthetically pleasing. Natural fluorescence also has components that benefit the appearance under natural and sunlit conditions, creating a certain “glint” that is defined as natural looking. Natural fluorescence is an important addition to composites used in direct composite bonding.

Treatment Planning Options

The options for treatment are presented to the patient so that, along with the dentist, a mutual decision can be made regarding what will be done. The orthodontic condition of the teeth must first be assessed. It may be wise to first reposition the teeth with either traditional orthodontic care or with Invisalign. Once completed, one can alter the position, shape, and color of the teeth with either porcelain or composite veneers. Another method is to temporarily alter the appearance with a “Snap-on Smile” technique in which an impression is taken and sent to the laboratory; the shade is chosen to create the desired look and color of the teeth.

Sequence

It is best to pre-evaluate what can be done on the teeth with orthodontic wax applied on the tooth structures. This is the traditional initial wax mock-up. Alternatively, composite can be used, a digital imaging software system may be used as well. These smile design programs can be used to create an esthetic look. The images are printed out and given to the patient to consider. Photographs and impressions are also taken. A wax mock-up can be constructed on a model in a laboratory, or in the office. A three-dimensional model is made to show the patient the desired look.

Assuming the patient has accepted the treatment, an appointment is scheduled. Anesthetic can be used or not. There is no need to numb the patient unless the procedure is more invasive. The dentist and patient commit to the procedure and determine whether it is necessary to reduce a tooth. Then the actual bonding process is undertaken, followed by polishing. A follow-up visit checks on the integrity of the bonding, to make sure the contacts are proper, to ensure that the margins of the composite do not impinge on healthy gingiva, and to protect the veneers with a night guard to prevent chippings from parafunctional activity.

The impression for the night guard is taken after the composite have been applied. If the patient is happy with the look, an impression can be taken then, and a night guard fabricated in the office. The type of night guard depends on the parafunctional activity. There are different types of designs, laboratory, and in-house. The NTI Tension Suppression System, made by Trident Dental Laboraties (Hawthorne, California), an anterior incline, covering either the entire arch or half of the arch from canine to canine. These soft splints have a soft interior and a hard exterior.

Treatment Considerations

Treatment depends on the position and shape of the teeth and whether they are chipped, discolored, and so on. Generally the dentist tries to prepare as little as possible. The goal is to be on the enamel and not in the dentin because enamel achieves a better bond. If the tooth exhibits sharp ridges or sharp edges, it is not necessary to reduce it. It may be possible to add the composite to it without reduction. The author’s practice is to bevel the enamel to create a flare so the finish appears flush with the superficial tooth structure. Beveling increases the surface area for maximum durability and esthetics.

If there is a very dark but limited discoloration, it is removed with a bur before application of composite.

Case 1

A female patient had short and narrow upper anterior teeth with space present interproximally. She was unhappy with her appearance (Figure 15-1, A and B). A treatment plan was established to include bonding the maxillary anteriors, canine to canine, while the rest of her upper dentition involved crown and bridgework. The end result portrays teeth that met her esthetic and functional expectations, and made her look attractive, and complemented her appealing facial features (Figure 15-1, C and D). The procedure took about 4 hours to complete and was done in a single sitting. She returned for a follow-up about 2 weeks later to make sure her gingiva were healthy, the bonding intact, and the esthetics up to her expectations.

Section B Transitional Bonding

Relevance of Transitional Bonding to Esthetic Dentistry

Transitional bonding allows practitioners to make major or minor changes in occlusion and esthetics with little or no reduction of tooth structure (Figure 15-2). With this approach it is possible to address cases with various esthetic problems, and, perhaps more important, health issues can often be treated. Examples include wear from bruxing; loss of occlusal tooth structure from erosion, decay, or fractures; and numerous teeth missing. Such situations may cause a decrease in vertical dimension leading to esthetic and functional problems. Restoring teeth that have worn down or are developmentally small so that the teeth are long enough or large enough to look more attractive without opening the bite could create a very deep overbite or other negative change. By increasing the vertical dimension one can often compensate for that.

Increasing the vertical dimension of occlusion (VDO) allows more space or clearance for restoring wear and lengthening the teeth. Most people will experience some loss of VDO with age. Many adults by the age of 50 could benefit from treatment that lengthens teeth for esthetic and/or functional improvements.

Relating Function and Esthetics

Often the dentist is faced with conflicting demands between function and esthetics. The first step in preparing for any major change is an esthetic evaluation of the patient, using photography, study models, and a clinical examination. For a patient with obvious esthetic shortcomings, an “improved smile” should not be the goal—that is too easy. The goal should be to determine what changes would provide the “best smile possible” for a patient. A systematic approach to smile analysis, using smile design principles, promotes this goal. This would include principles such as the height-to-width ratio of the esthetic zone, width-to-length ratio of the upper central incisors, arch and tooth widths and proportions, and smile line, as well as numerous others.

Once the esthetic treatment plan has been determined, then the tooth size, shape, and position are evaluated in terms of whether they permit the ideal functional outcome. At this point the dentist determines whether the centrals have been lengthened sufficiently and whether that would create a deep bite that might compromise occlusal function. Determination of whether, and how, to adjust the occlusion to obtain ideal function would be the next important step. That might include increasing vertical dimension or, rarely, decreasing it. After occlusal principles have been used to confirm whether this esthetic change will work functionally, then the proposed treatment plan for the patient can be presented.

There will be some cases in which the esthetic and functional treatment plans cannot be rectified. For instance, increasing upper anterior tooth length results in greater overbite unless the VDO is increased. If the patient is an occlusal Class II, increasing VDO to compensate for this will result in an increased overjet if the mandible is in centric relation. So a compromise may be required to either the esthetic or the functional plan.

Each case is evaluated considering the dental and periodontal condition, but occlusion is a major factor. Generally, the goal is to end up with teeth of normal size and length, having a normal amount of overbite and overjet, with anterior guidance in protrusive and canine guidance in right and left lateral excursions. Ideally the guidance provides posterior disclusion. In successful cases these esthetic and functional goals will have been achieved.

Clinical Considerations

Indications

A common situation is severe wear caused by bruxism, in which the patient has a reduced vertical dimension. Such teeth can be restored to their original condition or better. In less common cases there may be a skeletal growth problem that produces a mismatch in the size of the maxilla and mandible, and a Class II or III occlusion. In a Class III patient whose maxilla is underdeveloped and tooth display is less than desired, upper teeth can be lengthened and bulked out facially for better esthetics including increased tooth display and lip support. By opening the vertical dimension in such cases, it may be possible to alter these cases enough that a Class I occlusion results, because when the mandible is in centric relation and VDO is increased, overjet also increases.

Extensive decay is a less common indication. Decay may be severe enough that loss of tooth structure has allowed some collapse of VDO as with tooth loss. Restoration of the teeth including increasing VDO creates better esthetics and function.

Another indication is a bulimic patient who has sufficient erosion of the upper lingual surfaces that anterior teeth have supererupted. Such patients may not have experienced an actual loss of vertical dimension if the posterior teeth are intact, but opening the bite can create enough occlusal clearance to restore these eroded surfaces without having to prepare them as for a traditional restoration—probably a crown—resulting in more loss of tooth structure.

The prior examples all include increasing VDO. However, the majority of restorative cases will not require that. A more common indication would be a patient who has worn the anterior teeth enough that anterior guidance is deficient, with resulting posterior interferences. Restoring anterior guidance can be accomplished without opening the bite. Building more guidance than the patient originally had may also be possible—in patients with developmentally small teeth, for example.

Overbite is increased if incisal length is added without increasing VDO. As long as this result is not excessive, there is no reason to consider this a deterrent.

Ideally, incisal and canine guidance should be built so that the posterior teeth disclude in all excursions. This posterior disclusion protects the posterior teeth. If the anterior teeth continue to wear, then rebuilding them as posterior interferences recur is a valid option, as opposed to equilibrating away enamel on posterior cusps.

Another indication would be a patient who has a slide from centric relation (CR) to maximum intercuspal position (MIP). Rather than equilibrate (removing enamel) to correct this, consider positioning the mandible at the first point of contact (typically second molars touching on one side) and augmenting other cusp tips to create new occlusal stops to stabilize this mandibular position, which now becomes the MIP. The slide can be eliminated without any enamel loss. Anterior centric stops can be built by adding to the lower incisal edges, but more commonly the author achieves this by adding to the lingual of the upper anterior teeth; often in combination with lengthening the upper anteriors.

This type of approach provides the patient with a more ideal occlusion (CR now coincides with MIP, and anterior guidance provides posterior disclusion) and results in a more esthetically pleasing smile (restoring worn upper anterior teeth for more tooth display); and conserves tooth structure (little or no prepping, nor an equilibration, is required). Numerous other advantages are achieved as well, but these alone make this option very desirable.

Material Options

Glass ionomers and resin ionomers are not appropriate material choices because of handling and mechanical properties. The material should be sculptable and fairly viscous, providing enough working time to adapt the material and then cure on demand. These materials do not hold up well in the occlusal situations with incisal edges and built up cusp tips. The compressive and shear forces during normal mastication—and certainly during bruxing—would likely cause fracture and wear on surfaces subjected to mastication. Esthetically these materials are lacking, as well.

Amalgam is not appropriate because of its un-esthetic properties and the difficulty in building up an incisal edge. Certain posterior situations might allow amalgam to be one choice—for instance, if old fillings or carious lesions also need restoration.

Ceramics may be appropriate but only for a definitive restoration—not a transitional restoration. Cost is a significant disadvantage as well. There are situations in which it is appropriate to restore some teeth in porcelain, whereas other areas of the mouth are treated with transitional bonding.

Composite is the ideal material for this procedure. It is the most versatile of all restorative materials and offers many advantages including the ability to adhere to tooth structure even in the most non-retentive situations. Handling and mechanical properties allow these restorations to be built intra-orally and to survive for an extended time.

Advantages of Composite

A significant advantage of using composite and the transitional bonding procedure is that it is possible to be extremely conservative in maintaining tooth structure. The great majority of cases require little or no preparation. If preparation is needed, it is more conservative than with any other option.

Another advantage is that these restorations are very easy to adjust as the dentist is refining occlusion or completing esthetic contouring. The composite can be reduced quite quickly or can be added to without much difficulty, if necessary.

The technique is a direct technique, so it does not require laboratory involvement other than for a diagnostic wax-up. A wax-up on mounted models is recommended so as to create a template (e.g., putty index) to aid in the intra-oral procedure. An excellent alternative to obtaining a lab wax-up is for the dentist to use composite on the mounted models and mock up the case. This provides valuable practice in handling composite, sculpting, and contouring—all skills that enhance the intra-oral result.

Composite can be very esthetic. Although the transitional bonding technique does not maximize the esthetic results—because there is no layering of materials for effects such as incisal translucency or shade blending—a major esthetic improvement can still be expected. The author estimates that 70% to 90% of the esthetic improvement can be accomplished with transitional bonding as compared to “ultimate esthetics” composite restorations or porcelain restorations.

Another advantage is the option to upgrade the treated teeth to definitive ceramic restorations at some point (either all at once or phased in a few teeth at a time), using any remaining composite—after preparation—as a core buildup. Another option is to improve the esthetics with composite by prepping away a portion of the transitional bonding and then layering composites of varying shades and/or translucencies for a more ideal, esthetic result.

In addition, the compatibility of composite with natural tooth structure in terms of wear is ideal. Having a material that wears slightly faster than enamel is desirable because it is preferable to have restorations wear rather than opposing natural teeth, as may occur with porcelain restorations.

Fracture resistance is another advantage. The fracture toughness values are so similar between composite and feldspathic porcelain that there is no significant statistical difference. In normal situations when the restorations are built properly, there should be no greater incidence of fracture than with porcelain restorations, similar to the incidence with natural teeth, as well.

Marginal integrity is an advantage, as well. With composite it is possible to develop margins that are extremely smooth and sealed—especially supragingival margins ending in a feathered finish over a bevel on enamel. On the other hand, consider the margin of a class II posterior composite with a deep proximal box: there is little or no enamel to bond to, more distance from the curing light, potential moisture control problems—all routine challenges for achieving sealed, smooth margins in class II composites. Most of the margins built in transitional bonding are supragingival, so the situation at the margin is very different; there is enamel, and a beveled margin means minimal bulk of composite, making polymerization shrinkage less critical—all factors that lead to margins that are very resistant to microleakage.

Finally, fees should be lower than for definitive restorations. If only anterior teeth are being treated, the savings may not be as dramatic as when many posterior teeth are included. The time to complete anterior teeth should be less than performing definitive restorations, but there is a much greater differential when building up buccal cusps of posterior teeth. So when more teeth are included in the treatment plan, generally the savings grow exponentially. This is a critical advantage for many patients.

Stay updated, free dental videos. Join our Telegram channel

Jan 3, 2015 | Posted by in Esthetic Dentristry | Comments Off on 15: Direct Veneers

VIDEdental - Online dental courses

Get VIDEdental app for watching clinical videos