April 1, 2011
by Elliot Mechanic ,DDS
Why an article on dental temporization? After more than thirty years in dentistry I am thoroughly convinced that a dentist’s ability to create a lifelike functioning provisional is their pathway to achieve beautiful esthetic restorations leading to patient satisfaction. The ability to create artistic temporary restorations simply and quickly opens the door to a predictable end result. I graduated from dental school in the 1970s and clearly remember being told by other dentists and lecturers that if a dentist fabricated a temporary restoration that was too nice the patient possibly would not like the subsequent lab made ceramics or potentially would not return for a prolonged period of time as the provisional satisfied them. I have these words noted in several places in my school notes.
I graduated from dental school regarding the temporary restoration as a necessary evil to maintain space and to protect the prepared teeth until the final restoration was to be installed. Why waste time making something that was going to go into the garbage in the near future? It is ironic that today’s in office CAD CAM users (CEREC etc.) use as a selling point the time saved by not having to fabricate a temporary restorations. Do they not appreciate the value in evaluating form, function, contour, tissue and pulpal response before committing to a permanent restoration? They proceed immediately, the same day, to definitive milled ceramics. How can they be sure that they will satisfy the patients functional and esthetic needs?
In our daily practices we see different types of provisional restorations; the stainless steel crown, the block of acrylic placed on the tooth and subsequently hand trimmed by the dentist, the preformed plastic crown, the lab made relinable shell, freehand composite placement and provisionals fabricated from bis-acryl and a putty template., Sometimes we see teeth with no temporary at all and the patient living with exposed enamel and/or dentin awaiting the delivery of the definitive ceramics. Several brands of porcelain veneers advertise and claim that no provisionals are necessary. How then is the patient and lab technician able to assess and know exactly what shape, thickness, contour and style of teeth is desired? Is the smile design just “pot luck” and left to guesswork and chance? Do dentists just hope and pray that the patient will accept whatever returns from the lab?
Dental school gives us the basic knowledge and skills necessary to begin practicing dentistry. However, dental education does not end after graduation. The learning just begins. A multitude of educators and courses await us and there are numerous options and pathways to be followed in our dental journey. My dental evolution exposed me to dentists who spent an incredible amount of time and effort creating provisional restorations. Often several appointments were necessary to achieve the results that they desired. Once the temporaries were in place the dentists were in no rush to replace them. They were using the provisional as a testing ground and as a prototype to achieve a preplanned result. Not only does a meticulously made temporary give a patient the opportunity to see what their teeth would look like, but it gives them the ability to live with their new look for a while, show it to their family and friends, evaluate it’s contour, form, color, tissue levels and determine if they would like to incorporate any modifications before the permanent ceramics are to be fabricated. The dentist is better able to evaluate the patient’s function, periodontal response, vertical dimension and other esthetic factors to ensure that the permanent restoration is satisfying.
Once the patient approves the temporary restoration the dentist simply takes photos and models of it and forwards it with detailed instructions to the dental laboratory. The dental technician’s life will be made much simpler as the dentist eliminates the guesswork by providing an exact template of the final restoration they are to fabricate.1 The technician can then easily duplicate the exact length, width, thickness, form, midline, embrasures of the provisional by simply fabricating silicon templates to act as a guide. This technique will help eliminate costly remakes and cases going back and forth from the dentist to the lab where no one really knows where they are going. They may be hoping for a random miracle to happen or for a patient that is not fussy or hard to please and will accept anything. This rarely happens in today’s world as patients know what they want and are more demanding then ever. The standards of patient care and patient expectations are being elevated on a daily basis. A dentist’s ability to fabricate and modify provisional restoration is fundamental and the key to success for all the work to follow.
Achieving Facial Changes Through Dental Temporization
The mouth and lower one-third of the face is responsible for much of our visual perception of an individuals facial expression. The muscles of the mouth, known collectively as the orbicularis oris, are constantly moving, creating various facial expressions. Not even the eyes can express as much emotion as the mouth (Fig. 1).
Dentistry has the ability to influence facial changes by altering the shape, form and profile of a patient’s dentition and supporting structures. Sometimes dentistry is the initiator for subsequent facial changes involving various forms of plastic surgery. Almost in every case the rejuvenation of a smile leads to a new hairstyle, makeup and wardrobe. The media buzz today is the makeover and a “new you”. Often when a dentist changes the appearance of a patients smile the patient gains confidence, feels good about themselves and undertakes other procedures to enhance their looks.
The ability to visualize the end point of treatment before commencing is paramount for a successful treatment outcome. In many instances treatment plans are started with no set objectives nor a final vision of their endpoint. Dentists often randomly send patients for periodontal, orthodontic, and other treatments with no set plan. The results are often frustrating for the patient who has invested considerable expense, time and discomfort in anticipation of a pleasing result.
There is more to esthetics then science! What about the artistic side of dentistry? Human beings come in different sizes, colors, have different personalities and have different facial shapes. The goal of esthetic dentistry is to enhance what mother nature has given us and to be lifelike. Artistic smile design takes the scientific principles of proportion and the dentist as the artist adds their own creativity and variation (Fig. 2).
Natural perfection is full of detailed imperfection. Teeth have vertical irregularities, grooves, lobes, horizontal irregularities and depressions. These vary from person to person, reflecting age and personality (Fig. 3).
By understanding the characteristics of teeth we can modify them to project personality2. Dr Irwin Smigel refers to advanced esthetic dentistry as “plastic surgery without a scalpel.” (Fig. 4). Artistic dentists by manipulation of tooth form and position can yield significant alterations to a persons facial form. Simply changing the incisal corners and tooth length can create dental personality (Fig. 5). Teeth can be characterized by:
1) Lengthening vs. shortening
2) Flattening vs. rounding
3) Thick vs. thin
4) Detailed vs. flat labial surfaces
5) Gingival contours
6) Incisal corners (square, round, pointed)
Sequence of Establishing A Treatment Plan
Success in doing esthetic dentistry is based upon: 1) how well you examine 2) how well you treatment plan and 3) how well you present the treatment plan to your patient.
To create and present a complete treatment plan we need to perform a thorough dental examination including all of the following:
1) Listening to the patients’ desires and treatment objectives;
2) A complete series of intraoral and extraoral photos;
3) Tooth charting for caries, restorations, perio;
4) Verify endodontic and orthodontic status of the dentition;
5) TMJ and muscle exam;
6) Intraoral and soft tissue pathology exam;
7) Mounted study models in centric relation (Fig. 6).
The key to establishing a treatment plan is to be able to visualize the ideal end point of treatment and relate it to the patient’s current condition. A good point of reference is to compare the patient’s study models with the ideal typodont model all dental students are given. Every operatory in our office has a typodent model to enable our patients to visualize how an ideal dentition and occlusion appears (Fig. 7).
If the patient’s study model does not match the typodont the dentist should reflect, think and plan all the steps necessary that are needed to have the patients present dentition resemble the ideal setup of the typodont. We can then determine in what order treatment should be done. Our planning is based on our esthetic vision and we plan the patient’s function, structure, and biology accordingly (Fig. 8).
The Diagnostic Wax Up
One we have established a treatment plan we must be able to communicate our vision of the desired smile design to our lab technician so that they are able to share our vision. The technician should be able to create a diagnostic wax up from the parameters we provide. The simplest means of providing instructions for the wax up is by:
1) Accurate articulated study models poured with low expansion stone.
2) Photos of the patient including drawings of the desired changes (Fig. 9).
3) A smile design prescription giving the technician details of the contours and characterization we want the teeth to have.
By simply changing the contours, length and incisor corner of a tooth we can dramatically change the personality they project (Fig. 10).
Diagnostic wax ups should be paid for by the patient before they are sent to the dental lab. If a patient resists paying for the wax up how can we expect them to pay for the case without a hassle? A fair fee for the diagnostic waxup is an easy way to differentiate a patient who is serious about having treatment from one that is not.
Diagnostic wax ups are essential to direct our cases in the direction we wish them to go. They are able to give us many of the parameters we need for success:
1) They can redirect canted teeth and provide a means of assessing the midline
2) They can show the existing arch compared with a widened arch.
3) Spaces between teeth can be closed.
4) The shape, length and emergence profile of the teeth can be modified.
5) Minor crowding can possibly be corrected. More severe crowding usually requires orthodontics.
6) The patient’s bite can be altered. A complete occlusal equilibration can be performed in the wax up if the models have been taken in centric relation.
7) The wax up serves as a clear vision of the anticipated smile design.
A well-done wax up adds value and predictability to our treatment (Fig. 11). It provides a preview for the patient as well as for the doctor. Wax ups can provide differential diagnosis as by fabricating more than one wax up design the patient can compare options. The wax up serves as a template for the temporary restoration which is fabricated from a mold of the wax up. Above all the wax up gives the patient a realistic expectation of what to expect from the treatment so that surprises are minimized. The cost of a wax up should not be an issue as the wax up only adds benefits to the treatment.
Preparation Guide Fabricated from a Diagnostic Wax Up
Any dentist who has performed a significant amount of prosthetic procedures has undoubtedly had their lab technician inform them that they had not adequately prepared tooth structure to accommodate the proposed restoration. To achieve a good result they would have to reprepare the case. This is unpleasant and inconvenient for both the dentist and patient as another appointment is necessary, the patient has to be reanesthetized, the temporary removed, the teeth reprepared, a new impression and bite registration taken and new temporaries fabricated and placed. This is time consuming, painful and frustrating for everyone.
The diagnostic wax up can be used to create a preparation guide which prevents making mistakes as it enables us to visualize if the preparation is adequate to accommodated the final restoration. Without a guide it is often difficult to develop the desired arch form, correct axial inclinations, develop line angles and reduce the tooth adequately at the incisal edge where the preparation changes plane. The secret to visualization is a preparation guide which can be a clear plastic stent or made from putty (Fig. 12). Using a preparation guide will save the dentist and patient a lot of grief.
The Intraoral Mockup
However, successful esthetic dentistry can also be performed without a wax up. Instead of having a lab technician fabricate one the dentist can use his own skill by creating an intraoral mockup. This is basically doing free hand bonding in the patients mouth according to the desired end vision. In other words the dentist is using the patients mouth as an articulator and doing the mock up directly in it. This technique has advantages over the diagnostic wax up as the dentist can more easily relate his smile design to the patient’s lips, cheeks, face, musculature and other features. An articulator does not provide all of these influential surroundings. To create a useful intraoral mockup one must have good free hand bonding skills.
The ability of a dentist to visualize and to understand what he wants to achieve is paramount. The goals for the following patient are (Fig. 13):
1) Solidify the large anterior restorations (3 teeth are endodontically treated)
2) Expand the buckle corridors
3) Harmonize the gingival levels
Conservatively utilizing a diode laser and with free hand bonding we can achieve the same or even superior results to a wax up. I personally find it advantageous to slightly over build the teeth as it is much easier for me to reduce from the subsequent bis-acryl then to have to add to it with composite resin. We then can take an impression of the mockup, pour a study model and create a putty stent to act as a template for our provisionals (Fig. 14).
It is much easier to deal with a patient who knows exactly what they want. The most dangerous patient is one who does not know what they want or what they are getting. A dentist’s ability to create a beautiful temporary restoration enables the patient to be able to preview the end result of treatment before proceeding to the final restoration (Fig. 15). If the patient would like any modifications the dentist can simply modify the bis-acryl material with a composite resin restorative material. There is no other form of plastic surgery available which gives the patient a chance to “try before they buy.” Most plastic surgery procedures leave patients in bandages and it may be some time before they can assess the outcome of the procedure. Bis-acryl temporization allows the patient to see the results immediately eliminating surprises.
The provisional restoration also serves as a blue print for the lab technician as it is able to convey to him all the criteria necessary to provide a restoration that will satisfy the patient. The technician creates putty templates and guides from a model of the wax up and then using his skill duplicates the parameters in ceramics.
This article focuses on bis-acryl as a temporary restorative material because of its ability to be added to and modified easily. Continuing esthetic demands by the public have resulted in new technological developments with improved mechanical, physical and optical pr
operties. Provisional materials should display the following ideal properties:4,5
1) Minimal exothermic setting reaction non-irritating to the pulp and gingival tissues
2) They should be dimensionally stable
3) Resistant to fracture and occlusal loads
4) Should possess flexural and compressive strength
5) Should be quick and simple to frabricate
6) Should be esthetically pleasing
7) Should possess polished surfaces, margins and contours which promote healing and resist plaque accumulation
Poly methyl and poly ethyl methacrylate were the standard provisional materials used until bis-acryl came to market. One had the mix a powder and liquid to create a doughy acrylic blob, which would take several minutes to harden. These materials display higher strength then the bis-acryls. However, they are difficult to manipulate, display high volumetric shrinkage, are foul tasting and have a strong odor. Polymerization time is long and unpredictable giving off heat which can cause pulpal and gingival irritation.6 For the sake of smile design these materials are difficult to add and modify, limiting their value. These materials are still being used by many dentists, as they are familiar with the technique and desire their low cost.
Bis-acryl is today’s standard of temporization. Materials such as Luxatemp (DMG), Integrity (Dentsply), Protemp Plus (3M), display strength and esthetics. A putty template that has be been created from or diagnostic wax up or intra-oral mock up is filled with bis-acryl material dispensed from an auto mix cartridge and placed over the patients prepared teeth. It has a setting time of approximately two minutes from the time it is extruded from the cartridge. Most importantly it can be easily added to and modified with flowable, microfill or hybrid composite resin. It can be easily trimmed with diamonds, carbides or sand paper discs and a finishing glaze can be painted on to create a lustrous surface. Being a derivative of composite resin it displays natural looking esthetics. These systems are more wear resistant, color stable and have minimum odor compared to the methacrylates. They exhibit less shrinkage due to their glass filler content and possess low exothermal temperature values during polymerization.
1) Functions of the Temporary
1. The provisional restoration protects the prepared tooth from thermal, chemical, and mechanical influences.
2. It preserves the vertical and horizontal dimension of the prepared teeth.
3. Therapeutic agents can be applied under the temporary.
4. It allows evaluation of esthetics function and phonetics.
a) Facial esthetics
Lips: Full lips make teeth look smaller and darker. The temporary restoration can be modified to be larger so the teeth can be more visible. Thin lips may make the teeth look larger and lighter so the provisional can be reduced in size.
Aging: As people age the loss of elasticity in their tissues results in decreased lip mobility. The upper lip drops and results in less anterior tooth display. The dental effects of aging can be modified by lengthening the upper provisional and shortening the lower teeth accordingly.
Nasiolabial angle: Alterations can be done by adding or subtracting composite to the labial surface of the temporary in order to create more or reduce lip support.
b) Tooth position
Midline: The midline can be visualized in the temporary restoration. The midline should be straight and not canted7 Kokich concluded that a midline could deviate by 3 to 4 mm. until people would notice it. If the line that forms the contact between the two central incisors is perpendicular to the incisal plane and parallel o the long axis of the patients face the midline deviation is camouflaged. However, if the inclination of the central incisors deviates ( cants) by as little as 1 or 2 mm. it will be noticeable.
Incisal edge and tooth display at rest: A study by Vig and Brundo 8 concluded that young people display their upper teeth. As people age the upper lip drops and they display more lower teeth. So if our goal is to make someone older look younger we should lengthen their upper teeth.
The smile line should be evaluated if it is pleasant and fits the personality of the patient. The incisal plane and occlusal plane should align.
c) Gingival levels
Gingival levels should be in harmony. Older people have gingiva that does not align. If our goal is to make someone look younger be sure that their gingival levels reflect youth. Gingiva can be added by autograft, allograft or by orthodontic extrusion which can alter the position of the gingival crest. Gingiva can be reduced by gingivectomy, gingivoplasty, osseous reencountering and orthodontic intrusion.
d) Tooth arrangement
Incisal corners: Incisors can have square or round incisal corners. Canines can be flat round or pointed.
Tooth form: The teeth can be flat, round, thick or can have lobes creating a variation in labial surface. Characterizations can include chips, rotations and overlaps.
Personality: Teeth can be arranged into a natural looking configuration. They can be arranged to convey various images such as youth, aggressiveness, softness, or a natural look (Fig. 5).
e) The width of the arch
The dental arch should be U-shaped. By looking at the patient straight in the face we can assess if the buccal corridors are visible or if they require expansion. Composite resin can be added to the bis-acryl provisional to widen the upper arch. Some clinicians call this a non surgical face lift as it changes the patient’s smile dramatically and effects the supporting tissues surrounding the teeth (Fig. 18).
Bis-acryl is available in various tooth shades. The provisional serves as the patient’s preview of thintended shade of their final ceramic restoration. Often patients initially insist that they want very white teeth. Upon temporization they frequently visualize that the shade they initially insisted upon is much too light. They are able to change their mind and elect for a more natural looking color. Dentists must realize that their patients never went to dental school. Patients think that teeth should be white. The provisional allows them to judge for themselves.
2) Fabricating the Temporary
Once the teeth have been prepared utilizing the preparation guide, a provisional can be fabricated using a putty template (Fig. 19) and bis-acryl material. Bis-acryl is dispensed from an automix gun into the template which is then placed over the patient teeth and allowed to polymerize for approximately two minutes. The putty template is then removed from the patient’s mouth. The bis-acryl material usually will remain inside it. A scalpel blade can used to remove the excess material and the bis-acryl should be allowed to fully polymerize for five minutes inside the putty template. It can then be removed, trimmed, and placed in the patients mouth.
The ability of bis-acryl to be easily modified is the main reason it is the predictable route to successful smile design. Bis-acryl is basically liquid composite resin and once set can be trimmed and contoured with diamonds, carbides, discs etc. and can be modified and repaired using flowable and composite resin.
Once the temporary is placed in the patient’s mouth we are able to visualize and assess how the teeth appear in context with the rest of the face
. It is preferable to evaluate the esthetics of the temporary on a subsequent appointment to the day of preparation. The patient is not anesthetitized and the dentist and patient are fresh and more relaxed. The patient has been able to live with their new provisional for a while after having adjusted to the initial shock of the change that was done. By waiting and taking our time to assess the temporary we can better comprehend what is lacking and what should be altered.
Any brand of composite resin can be added to bulk out, lengthen and change the emergence and contours of the teeth. Midlines, cants and the incisal position can be adjusted in the bisacryl provisional (Fig. 20). It is much easier to make changes to the provisional by simple bonding to it then to return the final case to the lab to have the ceramics modified or remade. In dentistry nothing should be left to chance. Even if multiple modification appointments are needed it is worth the effort because ultimately time will be saved. Predictability is everything.
Once the patient approves the provisional restoration the dentist must simply take an accurate impression, a photo and choose the desired shade for the ceramics. The lab technician should be instructed to follow the shape of the temporaries as all the parameters for the final restoration have now been worked out (Fig. 21).
The model of the provisional restoration is able to communicate all esthetic and functional information to the lab.
1) Esthetic Information
• Tooth position
• Tooth arrangement
2) Functional Information
• Maxilla to face TMJ relationship
• Maxilla to mandible relationship
• Anterior guidance
• Specific functional needs of the patient
When the case returns from the lab with the final porcelain restoration it should be compared with the study models to confirm that they are identical. The patient should then be appointed and the case delivered. Seldom does the case have to be returned to the technician (Fig. 23).
One does not construct a building or a home without a careful study of its location and requirements and without an accurate set of blue prints. Detailed plans are given to the various contractors so they know the exact parameters of what they are suppose to do. Why should dentistry be different? Shouldn’t all dental specialists and laboratories be provided with accurate plans so they can do their job the right way? Meticulous treatment planning is the secret to having a happy patient.
The ability to create lifelike provisional restorations giving the clinician, patient and technician a precise visual and pathway will enable them to achieve the desired esthetic goals. The provisional restoration is an invaluable tool to achieve success.OH
Dr. Elliot Mechanic practices esthetic dentistry in Montreal, Quebec. He is Oral Health’s editorial board member for esthetics.
Oral Health welcomes this original article.
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