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Restorative/Preventive Dentistry: The Role of Composite Mock-Ups in Esthetic Planning

June 1, 2003
by Ronald Porth, DMD


Composite mock-ups provide a method by which to evaluate the esthetic demands of a patient’s dentition. The techniques of mock-up fabrication can be used as aids in both diagnostic and esthetic evaluation. When used diagnostically, they allow assessment either on study models or directly on unprepared natural teeth. When used for esthetic evaluation, mock-ups can be placed directly on teeth which are either totally unprepared, partially prepared, or fully prepared for the final restoration. They can be placed immediately before the preparation appointment or in advance so the patient has a trial period in order to evaluate them functionally and esthetically.

By following a set preparation impression sequence the mock-ups can be duplicated by the lab when fabricating the final restorations. The end result is that the dentist is able to control the esthetic artistry from the beginning to the completion of treatment.

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MOCK-UP MATERIALS AND TECHNIQUES

Flowable composite, of any brand, is the material of choice. It is easy to apply, flows readily, and sets with a smooth, esthetically pleasing appearance. Originally, regular composite was used but because of its tendency to lift off of surfaces as it is shaped, it was replaced with flowable which remains in place as it is sculpted. It can be applied as a thin veneer over study models or directly onto natural teeth.

Where gross tooth reduction is required it can be layered into any desired thickness. A fine-bladed carver such as a #3C1155 IPC (American Standard) can be used to shape the interproximal and gingival areas. Working time is increased by removing the overhead dental light source. After light curing a finishing bur such as a twelve-bladed #7901 is normally all that is needed for shaping.

PARAMETERS FOR ESTHETICS

In esthetic cases the central incisor forms the essence of the smile. The shape and position of the central incisor is dependant on the general parameters of smile design. These can be dictated by basic prosthetic principles such as those used in determining denture teeth arrangements. Facial form dictates tooth form, lip line determines incisal length, and basic phonetics determine the incisal edge position. The angulation of the incisors, midline position, and gingival height are other factors that must be considered.

Patient preference is another important factor in determining the final esthetic outcome. It may be determined by presenting to the patient a number of smile options. These may include: before and after photographs of previous cases, magazine covers showing smile varieties, and digitally enhanced photographs. Digitally enhanced smiles can be easily produced using computer programs such as Dicom Imaging Systems used by the author, which allows the placement of a variety of smile options into a digital photograph of the patient.

Before presentation to the patient a diagnostic mock-up can also be prepared on study models. It will often reveal limitations in creating the idealized digital smile due to the patient’s arch form or tooth position. The idealized computerization can then be presented to the patient along with the diagnostic model to demonstrate the limitations. Orthodontic, orthognathic and periodontal treatment may be indicated prior to restorative treatment. The opportunity to visualize the treatment limitations enables the patient to make a more fully informed treatment decision.

DIAGNOSTIC MOCK-UP ON STUDY MODELS

The preparation of a mock-up on a study model can be a very simple yet effective diagnostic aid to help in the overall diagnosis of a case. The amount of tooth reduction will often help determine whether orthodontic or endodontic intervention will be required.

For the study model mock-up a #1157 bur is used to create a rough veneer preparation on the tooth to be treated (Fig. 1). Composite is then flowed from mesial to distal in rows beginning at the gingival. In cases where the incisal is to be lengthened, the operator places a finger lingual to the tooth (Fig. 2) and flows the composite up onto the finger (Fig. 3). After setting with a curing light a twelve-bladed #7901 bur is used to quickly shape the incisal to the desired length and form. In cases where the entire tooth is to be repositioned finger support on the lingual allows for incrementally set layers to be built up until the desired shape is achieved.

By leaving the majority of the lingual surface unprepared the operator is able to determine the gross labial reduction required at the preparation appointment simply by examining the study model. The mock-up aids in the overall diagnosis by helping determine the amount of tooth reduction necessary.

DIRECT TOOTH MOCK-UP TECHNIQUE

The same technique used on study models can be used directly on teeth to be prepared for veneers or crowns when the length and or shape is to be altered. The amount of tooth removal is determined by the degree of change required in tooth shape or position. When moderate change is required, primarily to improve contours, a rough veneer prep is first prepared on one of the central incisors (Fig. 5). By removing just the depth of a veneer prep, the flowable composite bead of material extrudes from the syringe tip in a thickness close to the thickness of tooth that was removed. The flowability of the material results in a very smooth surface after light curing which helps to reduce finishing time on the labial. Ideally, the only finishing required should be to the incisal edge.

If incisal change is the only requirement then the incisal area can be lightly grooved using a twelve-bladed #7901 finishing bur. The area is then etched and bonded and composite is flowed onto that area only. If the incisal is also to be lengthened, the study model technique is used whereby a finger is placed behind the tooth and the composite is flowed up onto it (Fig. 6). The twelve-bladed finishing bur #7901 is used to shape the incisal edge (Fig. 7) to the desired length (Fig. 8). This can often be accomplished without anesthetic.

For the tooth requiring the most extensive modification such as in cases where the diagnostic mock-up indicates that endodontic treatment is required to reposition it, the preparation may involve removal of the majority of tooth structure. Rebuilding is then done in layers, which are individually light cured with lingual digital support — the same technique used on study models.

Immediately after the mock-ups are completed on the teeth they can be analyzed in relation to function and esthetics. In cases where the treatment was accomplished without anesthetic the incisal edge, lip position, and phonetic assessment can also be examined at this time.

IMMEDIATE STUDY MODEL MOCK-UPS

This type of mock-up can be useful in situations where a patient requests an alternate treatment to the one proposed during the consultation. In this case (Figs. 9 & 10) dramatic changes were required to improve the appearance of the incisors. The patient was presented with a treatment plan, which included orthodontic treatment as an ideal option. He became quite dismayed and asked if anything could be done without orthodontic treatment.

Sitting chair-side, with the patient watching, it took only a matter of minutes to show him what could be accomplished with endodontic and restorative treatment (Fig. 11). The patient chose to proceed and the completed treatment was a definite improvement esthetically (Fig. 12). His comment following cementation of the crowns was very gratifying for as he left the operatory he stated very simply: “Thank you for my smile.”

DIRECT TOOTH DEMONSTRATION MOCK-UPS

The same direct technique can be applied in some cases to unprepared teeth. The mock-ups allow the patient to visualize the proposed treatment. A case involving the restoration of peg laterals is a good example (Fig. 13). Mock-ups were placed on the unprepared teeth without bonding to give the patient an easily removable esthetic transformation (Fig. 14). Restorative treatment with porcelain veneers was later completed to provide the
permanent esthetic result (Fig. 15).

ANTERIOR MOCK-UP CASE STUDIES

The following three cases illustrate different degrees of complexity of mock-up fabrication where the maxillary incisors are being treated. Of primary importance in fabricating direct mock-ups is the determination of the shape and length of the maxillary central incisor. The degree of difficulty increases with the amount of change required. This will have been determined by the diagnostic mock-up.

Case One (Figs. 16 & 17) is an example of a patient desiring a fuller, whiter smile. The mock-ups were attached to the existing composite veneers with minimal labial reduction using depth cutting burs to create retentive grooves and then extending the mock-ups using the technique previously described to increase incisal length. They were adjusted to the patient’s phonetic requirements and remained in place for one month prior to final restoration (Fig. 18).

Due to the extent of the treatment a face-bow mount and fully adjustable Denar articulator was used. Full porcelain crowns were placed on the maxillary anteriors and porcelain to metal crowns on the mandibular anteriors. Figure 19 shows the two-year follow-up of this case.

A heavily worn anterior dentition is shown in Case Two (Figs. 20 & 21). The patient was not willing to accept recommendations to have the teeth repositioned orthodontically prior to restoration and due to the fact that the occlusion was stable the primary goal was to correct the incisor angulation. In creating the mock-ups the lingual contours were maintained but the labial contours and incisal edge position were changed. All three anterior teeth on the right side were built up with mock-ups (Fig. 22) before treating the left side (Fig. 23).

As no adjustments to the mock-ups were required porcelain fused to metal crowns were placed one week later. At the two year follow-up appointment the restorations continue to fulfill the esthetic and functional needs of the patient (Figs. 24 & 25).

The final case (Case 3, Fig. 26) involved gross tooth reduction in order to realign the malpositioned incisors. A face-bow mount and a fully adjustable Denar articulator was used due to the excessive amount of tooth repositioning required. The central incisor #11 was repositioned and contoured esthetically (Fig. 27) before proceeding to the adjacent incisors. The mock-ups (Fig. 28) remained in place for a two-week trial period prior to tooth preparation, followed by seating of porcelain to metal crowns. Figures 29 and 30 show the one-year follow-up of this patient.

LAB TRANSFER OF ESTHETIC MOCK-UP

One of the necessary requirements in this type of esthetic treatment is to transfer the results, after they have been determined directly on the patient, to the laboratory. A final tooth preparation and impression taking sequence facilitates this transfer of esthetic information. The mock-ups are first prepared on the teeth and then one or two full arch bite impressions are taken. The teeth are then prepared in an “every other order.” This leaves an unprepared tooth adjacent to each prepared one (Fig. 31).

A final impression is taken at this stage; a standard full arch tray may be used as occlusion is not critical at this point. The lab is then able to match the exact shape, contours, and incisal edge position of the mock-ups on the unprepared teeth as they build up the new restorations on the (every other) prepared teeth.

After this first impression the preparations are completed and a second, “final” impression is then taken of all the prepared teeth, all at the same appointment. The lab then prepares the teeth according to the predetermined esthetic requirements. The esthetic outcome is ensured because it is in accordance with the needs and desires of both patient and dentist. The temporaries are also fabricated to match the mock-ups by using one of the impressions taken of the mock-ups prior to tooth reduction.

The patient can assess the new appearance and function during the time the lab is fabricating the restorations. If the patient requests changes, these can be relayed to the lab either verbally or by sending a new study model after the changes are made on the temporaries.

The impression technique employed is the Full Arch Tripple Tray Technique developed by the author (Fig. 32, Oral Health Journal, December 1999). It facilitates impressions of treatment in multiple quadrants, in the anterior and/or posterior, using multiple bite trays.

The cases in this article have all been completed under the expert technical supervision of Noriko at Aurum Laboratories in Vancouver, BC.

ADVANTAGES OF DIRECT MOCK-UP

One of the main advantages of direct mock-ups of teeth prior to preparation is that they allow the dentist to determine the esthetic result directly on the patient. At times this can be done prior to anesthetic which allows for the visual checking of length and shape according to lip line, as well as phonetic evaluation of incisal edge position.

In addition, the mock-ups can be copied for temporization and most important, the laboratory can reproduce the predetermined esthetic result. This then determines that the esthetic outcome of the treatment is in accordance with the patient’s needs.

The use of indirect mock-ups on study models allows both the visual confirmation of the practitioner’s ability to treat cases in the manner he or she proposes, and the ability to assess computer generated images. In addition all of the mock-ups can be useful as marketing tools.

THE ULTIMATE ESTHETIC CHALLENGE

For the dentist interested in promoting esthetic dentistry, nothing is more essential than the need for an esthetically pleasing smile. The author realized this and in 1988 decided to take matters into his own hands. Using two mirrors he was able to execute a significant esthetic improvement in his own appearance (Fig. 33) with composite veneers (Fig. 34) and without the need for anesthetic.

In 1997, however, the need to place porcelain veneers became evident. Again a desire to “do unto myself as I do unto others” compelled him to self-treatment. The need for anesthetic became apparent and the Intra-ligamentary System proved to be most effective for self-administration (Fig. 35). The four incisors were prepared for veneers (Figs. 36 & 37) and the lab was instructed to duplicate the form of the previous composites by following the contours on the “every other” impressions. The results continue to be very positive esthetically six years later (Fig. 38), and have given him a special appreciation for the personal benefits that esthetic changes can have on a person’s life.

Dr. Ron Porth is in general practice in Abbotsford, BC. He has presented his Nd:YAG Laser Endodontic Disinfection study at laser conferences of the American Academy of Laser Dentists, the International Society of Laser Dentists, and most recently at the European-German Society of Laser Dentists E.S.O.L.A. meeting in Vienna, Austria, 2001.

Oral Health welcomes this original article.


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