April 1, 2010
by Alain Methot, DDS
Aesthetic results come from the practitioner’s combination of clinical smile design principles and artistic judgments. Each practitioner has their own vision of the final smile. The main goal is to provide a natural and pleasing appearance for the patient’s newly restored smile.
For the last decade, most of the published articles in aesthetic dentistry discuss the same principles in smile designs. Golden Proportion, gingival architecture, emergence profile, and shape related to facial anatomy….1 These same principles have been used without any advances in technique or case presentation until now. Many options are available to pre-design the most appropriate smile for the patient, from computer imaging and diagnostic wax ups to simply drawing on a patient photograph.2
This article will describe a new simulation method combining many of the old techniques, which is so predictable that it minimizes any potential difficulties during the treatment process. By creating a virtual diagnostic wax up using computer imaging techniques, treatment is guided simply by utilizing a single facial photograph in conjunction with a computer software program.
This article will demonstrate the accuracy of imaging using the “M ruler”, a diagnostic tool for smile design using an algorithm based on the upper central width and the width of the patient’s maxillary complex that will give the ideal disposition of teeth in the patient’s face.3
Each patient has a unique maxillary width and upper central width. The “M ruler” and the software program will diagnose facial and dental asymmetries and provide the most aesthetic tooth position, shape and smile design to fit in that patient’s facial frame.
Diagnosis is simply achieved by dropping a facial photograph into the GPS golden positioning software program where the program will then establish the best smile parameters for the patient.
Once the photograph has been taken we will use the photographic information to determine the soft tissue contours of the patient’s face.
Without a patient’s facial data, it is impossible to make a proper evaluation of the smile and it’s harmony within the patient’s face. As part of the diagnosis, it is necessary to evaluate facial and dental asymmetries. As practitioner we need to think “global aesthetics” by using a full facial view in the laboratory; close up pictures of the patient’s smile help for the smile design but the complete picture is required to evaluate how the smile looks in context of the face.4
Compared to the Golden Proportion system, that can only offer one ratio: 1:618, the “M ruler determines the patient’s own unique ratio for smile design.
The standard Golden Ruler works well for the determination of the central incisor ratio, but in the majority of cases, fails to provide a pleasing smile when used to develop the proportion of central to lateral to cuspid, thus forcing the practitioner to artistically tweak the case before finishing causing loss of time and often compromising the outcome.
The M ruler is an analytical device based on a specific algorithm that is adapted from the golden proportion principles but is fine tuned to provide an individualized proportion for each individual patient. Using the photographic data, the software program creates a harmonized smile for the patient’s overall facial appearance; the M ruler is placed in the computer simulation, on the dental midline of the patient’s full face photograph in relation with the patient central width and inter molar distance.
This diagnostic tool will ultimately allow the practitioner to determine the treatment options appropriate for this patient, such as orthodontics, crowns, implants, bridges, full or partial dentures and will help the practitioner to discuss these options with the patient during a consultation using the computer software simulation.
A full face photograph of the patient face is taken directly in front of the patient by placing the lens in line with the nose of the patient noses. (Figure 1)
This 54 year old patient’s chief complaint was that she wasn’t happy about her smile, but wasn’t sure what specifically she didn’t like. This patient had no medical contraindications to treatment. Dental history revealed extractions and veneers done 10 years ago. The patient wanted to change her veneers. She presented an inverted smile line caused by an exaggerated curve of Spee and poor central length. She had a CL III malocclusion involving inter dental spaces discrepancy, with an overjet of 1mm and an overbite of 0.5mm (Figure 1a, 1b)
The patient exhibited multiple missing teeth and a gingival recession of 4mm on the upper right first bicuspid. The upper dental midline was shifted to the right 1.5 mm compared to the facial midline. The upper lateral incisors appear large and the centrals small when compared to the maxillary complex.
The treatment plan developed by the virtual diagnostic wax up established by the Dental GPS software program, was to make the centrals longer to create a smile line that follows the lower lip, a gingival surgery to correct the recession on the upper right first bicuspid, consolidate the gaps created from the previously missing teeth…whiten the teeth, and restore a more pleasing proportion to the smile.
The patient was informed of the treatment options, including no treatment at all, the risks and benefits and costs of treatment. Informed consent was obtained for the recommended treatment plan.
To accomplish this 4 different treatment phases were proposed:
Orthodontic treatment was undertaken to align the arch form and to create an idealized spacing so that new veneers from bicuspid to bicuspid would then be in M proportion and finalize space closure. (Figure 2)
Orthodontic treatment consisted of Invisalign (Align Technology, Santa Clara, CA). The orthodontic prescription was sent to Invisalign to do a ClinCheck. A ClinCheck allows the practitioner to visualize the proposed orthodontic treatment and teeth movement before accepting the case.
Sixteen aligners were needed to complete the alignment of teeth in a period of 32 weeks to correct the gingival architecture, the occlusal contacts and arch form. The first aligners are demonstrated in a side view (Figure 3a).
The final aligners in ClinCheck show the estimated correction in a lateral view in Figure 3b, and in a frontal and occlusal view in Figure 4.
Figure 5 show the facial photograph after completion of orthodontic treatment.
Orthodontic aligners are an excellent method to obtain an accurate positioning of teeth in the dental arch using the M ruler when an exact spacing is predetermined; and to obtain predictability in an aesthetic set up. Aligners are not very reliable however for extraction cases or to move teeth by translation on many mm. In this case a space of 1mm between each tooth from bicuspid to bicuspid was specified in the Invisalign orthodontic prescription.
The patient was referred to a periodontist for gingival graft procedure to correct the recession on the upper first right bicuspid
An implant was placed to replace the missing lower right second premolar (Figure 6)
In office Zoom Advanced Power Whitening of the lower arch followed by four nights of take-home whitening to stabilized in the effects of the in-office whitening. (Discuss Dental, Culver City, CA)5
The treatment plan called fo
r 10 veneers from second bicuspid to second bicuspid on the maxillary and crowns on the lower left cuspid, first premolar, and an implant supported crown to replace the lower right second premolar.
Alginate impressions of upper and lower arch were poured with white stone and sent to the laboratory with a symmetry bite registration6,7 using Luxabite (DMG America, Englewood, NJ) indicating to the laboratory the proper occlusal plane and midline.
At this stage no virtual wax up from the simulation was sent to the laboratory, the laboratory technician created the ideal diagnostic wax up from an artistic point of view.
The wax up was used to fabricate a prep guide to do minimally invasive preparations, to control ceramic minimal thickness to maintain structural integrity of the tooth.8
A silicone impression using Siltec Putty (Ivoclar Vivadent, Amherst N.Y) of the wax up was used to apply provisional material Luxatemp A1 (DMG America, Englewood, NJ) to the prepared teeth.
The resulting smile design from the wax up did not result in a pleasing smile when put into the facial frame.
One method of correcting the appearance of the provisional’s is by adjusting them directly by adding composite or removing provisional material in order to achieve the desired aesthetic result. This is undesirable because it is a time consuming procedure and it becomes a smile design based on artistic perspective. It is often more difficult to reproduce the minor variances to enhance the smile design directly in the mouth and it usually ends in a poor result with operator and patient frustration.
Lab communication is a critical factor in the development of a diagnostic wax up. The lab technician requires a soft tissue evaluation or clinical photographs. In order to manage these problems, the “Dental GPS software” (Dental GPS Laval Canada) is utilized the facial photograph of the patient face to create a virtual wax up reproducible in laboratories.
In the following procedure; no correction where made on the provisionals in the patient’s mouth, instead the facial photograph of the patient smiling with her provisional’s was inserted in GPS software. (Figure 7)
The facial photograph was taken with the patient’s Frankfurt plane parallel to the floor. The Frankfurt plane is the reference position to take the picture in GPS, this plane is a line passing through the Porion and the Orbitalis; 2 radiologic points on the bone (Figure 8) represented by the red line.
The picture was introduced in GPS software and the long axis of the face was aligned perpendicular to the floor.
The inter-pupillary line is not important in this process; often one eye is lower than the other. For that reason the long axis of the face is the reference position for diagnosis and treatment plan in GPS.
The case was returned to the laboratory using a GPS prescription including the changes of the provisional’s on a GPS virtual wax up showing the corrected and final smile. The electronic prescription was sent to the lab with upper and lower casts of the provisional’s.
To be able to reproduce the virtual wax up on final restorations it is imperative to capture the aero spacial position of the maxillary and transpose it on the articulator, axes X and Y are needed. To be able to transfer this data on the articulator a “Fox plates” with a vertical member attach to it was needed. Kois Dental Facial Analyzer (Panadent, Avenue Colton, CA) was used for that purpose (Figure 9).
Once the position of the maxillary cast correlate’s between the picture and the articulator (Figure 10, 11a and 11b) the M ruler guide is printed from the computer (Figure 12) and then positioned on the platform of the articulator in relation with the provisionals (Figure 13). It is then possible with GPS software to do the final restorations based on the M ruler coordinates X and Y from the virtual wax up of the patient provisional’s.
The M ruler in the virtual wax up guides the lab technician to position each final restoration according to length, width and to establish the new occlusal plane and vertical dimension of occlusion. The occlusal plane has been changed on the virtual wax up in harmony with the smile line (Figure 14, 15). The lab technician will be able to reproduce those changes with incredible accuracy directly on the ceramic.
Ten Empress Veneers (Ivoclar Vivadent, Amherst, N.Y) with cutback technique9 were fabricated based on the smile design using the M ruler printed guide. (Figure 16)
The ceramist simply follows the GPS electronic prescription to create the final restorations. It should be noted that the emergence profile of the upper right first and second premolars is more accentuated then the emergence profile of the upper left first and second premolars to accommodate the new smile design.
The correction of the axial inclination differences between the provisional (Figure 17) and the final restorations are noted (Figure 18).
During the treatment process, anterior guidance was re-established so that now in protrusive the TMJ is guided by interocclusal CL I relationship and a Cuspid rise disocclusion during lateral excursion.
The final restorations were cemented in mouth with Variolink (Ivoclar Vivadent Amherst N.Y.) using an A3 shade, without any coronoplasty (adjustments in shape). (Figure 19)
The pre op (Figure 20) and the post op photograph of the patient (Figure 21)
The dental midline has been corrected; both upper centrals are dominant and were designed to this specific width and length by the GPS program in order to correctly “fit” the patient’s face. The smile line has been corrected to follow the lower lip line contour and the final smile is now in harmony with the patient face.
By using a simple pre-op facial photograph of the patient and M ruler, dental practitioners can diagnose, treatment plan and do a virtual wax up using “GPS” software. The resulted electronic prescription can then be e-mailed to the laboratory to produce an accurate wax up of the proposed smile.
Simple protocols will save lots of time and adjustments chair side, with imaging and scientific tools like the M ruler, practitioners are able to fit the best possible smiles into the patient face by trying different simulated smiles before doing the final restorations creating predictable and pleasing smiles for our patients. OH
1. McLaren E, Rifkin R.Macroesthetics: Facial and Dentofacial Analysis Oral Health Nov. 2005 Vol 95
2. Rufenacht C.R. Fundamentals of Esthetics Quintessence 1990
3. Methot A. M Proportions The new golden rules in dentistry, Canadian Journal of Cosmetic dentistry 2006, Volume 1, 34-40
4.Morley J. The Role of Cosmetic Dentistry in Restoring a Youthful Appearance, JADA, August 2009
5. Soll J, R. Mulholland S. Laingchild T. Elements of a Make Over Oral Health, April 2008
6. Full-Mouth Rehabilitation and Bite Management of Severely Worn Dentition Journal of Cosmetic Dentistry
7. Margeas, R. A simple technique guide for a complex veneer case Oral Health, April 2000, pp 75-89
8. Goodlin, R.M. Minimally invasive Dentistry Cdn J Cos Dent Vol 4 No1 April 2008 pp 43-45
9. Magne P, Belser U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Hanover Park, IL: Quintessence Pub.; 2002.
Dr. Alain Methot is the CEO of GPS, he practices in Laval, Quebec, Canada
Oral Health welcomes this original article.