What is the most recognizable signal in the world? Consider this answer: “The smile is the most recognizable signal in the world. Smiles are such an important part of communication that we see them far more clearly than any other expression. We can pick up a smile at 300 feet—the length of a football field.”1
What makes a person attractive? According to studies such as those done by Karl Grammer at the University of Vienna and Regents professor Randy Thornhill of the University of New Mexico, beauty is simply balance. Physical symmetry is perceived as a reflection of fertility, youth, health, and strength. Nancy Etcoff, author of Survival of the Prettiest: The Science of Beauty, says, “Our sensitivity to beauty is hardwired—that is, governed by circuits in the brain shaped by natural selection. We love to look at smooth skin….and symmetrical bodies….”
In addition, symmetry has been correlated with sexual activity. Thornhill, a biology professor, and University of New Mexico psychology professor Steven Gangestad surveyed hundreds of men and women. They found that men who looked symmetrical started having sex 3 to 4 years earlier than their asymmetrical counterparts. In addition, women preferred the scent of symmetrical men and vice versa.2
Dentistry has played an integral part in helping people achieve the goals of improved and more youthful appearance. In many instances, a person not only wants to look younger, but also wants to correct asymmetrical features. The popularity of television shows like ABC’s “Extreme Makeover” illustrates the public’s fascination with cosmetic dentistry and plastic surgery. Facelifts, rhinoplasty, eyelid lifts, liposuction, collagen injections, and implants in cheeks and breasts have kept plastic surgeons busy. Dental practices now more than ever before see patients who are interested in improving their smiles. The motivation for these dental procedures is for personal improvement or professional reasons.
THE GOLDEN PROPORTION, MARQUARDT MASK, AND LIGHT REFLECTION
Dr. Stephen Marquardt is a retired plastic surgeon who researches attractiveness. He has found that the mathematical ratio known as the Golden Proportion (1:1.618, also known as the term phi) appears in beautiful man-made structures (eg, the Parthenon) and natural objects (eg, seashells, flowers). In looking at how the Golden Proportion fits the human face, Dr. Marquardt created a “mask” that is symmetrical and can be superimposed on faces. The closer a face fits into the mask, the more attractive the face is perceived to be. On Dr. Marquardt’s Web site, beautyanalysis.com, examples such as the classic beauty Marilyn Monroe and the well-known actor Pierce Brosnan are shown to fit well into the mask.
Hollywood makeup artist Jeanine Lobell states, “Creating symmetry is all about using light, dark, and reflection.” She also says that nobody’s perfect and one shouldn’t get carried away seeking symmetry. Ms. Lobell’s comments are applicable to dental aesthetics. First, she implies that how an observer perceives a face is determined by the way light interacts with that face. Second, she recognizes that symmetry is a goal, but there are limitations to achieving it, and one needs to be realistic about creating symmetry. These are concepts that dentists should keep in mind when performing smile rehabilitation.
THE CHALLENGE
Considering the importance of a smile in human interaction, as dentists we have the primary responsibility to help people obtain the smiles they always wanted or recreate the smiles they once had. Achieving an aesthetic smile in an asymmetrical maxilla can be one of the most difficult challenges we face. The difficulties usually fall into 2 categories.
First, there are the aesthetic issues. Many things need to be considered. For example, where does the upper midline fall? Does it line up with the lower midline? How can we proportion and position the teeth so they are pleasing to an observer as well as the patient? Do the teeth look long enough in relation to the person’s face?
The second category includes occlusal problems. With an asymmetrical upper arch, the upper and lower teeth cannot fit into an ideal occlusal relationship. If one side of the maxilla is missing a tooth, all other tooth positions and articulation are thrown off. If the missing tooth is in the aesthetic zone, creating an attractive smile is often very difficult.
In conducting a literature search, I found that articles dealing with asymmetry are most often related to orthodontic treatment. There were no articles written about treating maxillary arch asymmetry from a restorative viewpoint. While orthodontic treatment can sometimes be the answer, it is not always possible and oftentimes will not really solve the problem aesthetically.
This article will discuss the various components of an attractive smile, and with 2 cases will illustrate how an aesthetic result was created in the presence of maxillary asymmetry. The first case involves a missing upper left lateral incisor. The second case involves a missing upper left bicuspid. The second case is complicated further by the patient having an excess of visible gingiva, known as a gummy smile.
COMPONENTS OF AN ATTRACTIVE SMILE
There are 3 basic components of a smile: the teeth, gingiva, and lips.3 In each component are elements that contribute to the attractiveness of a smile. With respect to the teeth, the color or shade of the teeth influences what an observer sees when someone smiles. Tooth positions and shapes of individual teeth also impact the final appearance of the smile. Finally, the silhouette of the upper teeth against the lower lip, also referred to as the smile line, is very important. The smile line usually slopes upward as it moves from the center of the smile towards the corners of the lips. If a person’s smile line takes a direction opposite to what it should be, the teeth appear worn, and the person may be perceived as unattractive.
The gingival tissues are the second component of a smile. Do the gums appear healthy or inflamed? Are the gingival zeniths in the correct locations? Do the gum tissues appear symmetrical on both sides in the aesthetic zone? The answers to these questions will also impact how a smile is perceived.
The third component of a smile—the lips—defines the aesthetic zone. There are 3 types of upper lip lines: high, medium, and low. The contour of the upper lip in a smile influences where the gingival height should be. The contour of the lower lip influences the positioning of the incisal edge positions of the upper teeth. The degree of lip retraction when a person smiles will influence the number of teeth that constitute a full smile for that individual. The shape, lip line, and contour are sometimes referred to as the lip drape.
How the 3 components of a smile relate to each other will determine whether a person’s dental appearance is considered healthy and attractive. Satisfying the individual elements of each component and harmony among these components will lead to a smile that is pleasing to an observer. When asymmetry is present, it creates a state of disharmony that must be overcome.
Case 1
 |
| Figure 1. Preoperative smile attempt. |
Laura is a dentist who attended one of my courses. At the end of the day, she said she wanted to call me and see what we could do about her smile. At her first visit, we took several full-face images of her trying to smile. As you can see, she did not smile fully and her facial muscles didn’t work in a relaxed fashion (Figure 1). There was an obvious strain with smiling. In addition, we discussed what her goals were and how she wanted her teeth to look. This is a critical step in any case involving a change in dental aesthetics. The patient’s input is extremely important and helps to increase the chance for a successful result. At this time, the slight crowding of Laura’s lower incisors was not a concern for her.
Additional images and stu-dy models were made, and a comprehensive clinical exam and full series of x-rays completed. The close-up images of Laura’s smile and teeth reveal many things. Her upper right central incisor (tooth No. 8) was clearly darker than her upper left central incisor (tooth No. 9, Figure 2). Her dental midline was not truly vertical and was skewed to the left (Figure 3). Laura’s upper right second bicuspid (tooth No. 4) was positioned palatal to the other teeth in this area (Figure 4). Her upper left lateral incisor (tooth No. 10) was missing. Her upper left canine (tooth No. 11) had discolored bonding on it. It was obvious that someone had tried to make the canine look like a lateral incisor and simultaneously close the space left by the missing lateral incisor.
A general rule for this type of case is that you do it 3 times. The first time is with a diagnostic wax-up, the second time is with the temporary restorations, and the third time is with the definitive restorations. The diagnostic wax-up serves as a communication tool to see that the patient’s goals are being met prior to picking up a handpiece. In addition, the wax-up is the road map or 3-dimensional blueprint to the end result. We must be able to see the case completed in our mind before doing it with our hands. The diagnostic wax-up for Laura is shown in Figure 5.
 |
 |
| Figure 2. Preoperative smile. | Figure 3. Intraoral view of teeth. |
 |
 |
| Figure 4. Second bicuspid in palato version. | Figure 5. Diagnostic wax-up. |
Treatment Plan
The treatment plan for Laura included bonded direct composite restorations for carious areas and porcelain laminates to correct her smile. The space left by the missing left lateral incisor would be closed. The discrepancy between facial and dental midline would still exist after treatment, and the midline discrepancy between upper and lower arches would be acceptable so long as the upper midline was truly vertical. Prior to treating Laura’s smile, the restorations that needed to be done for existing caries were completed. After anesthetizing her, prewedging was accomplished using Sycamore Wood Wedges (Premier Dental USA). A caries-detecting solution, Sable Seek (Ultradent), was used to help identify any remaining caries after most of the excavation was completed. Using this type of product allows the practitioner to be as minimally invasive as possible. A total etch and seal of the prepared surfaces was completed with Ultra Etch (Ultradent) and PQ1 (Ultradent). To achieve maximum bond strength, it is important to evaporate the solvent in the bonding agent. After curing the adhesive, the restorations were built up with Charisma (Heraeus Kulzer) and cured with the Demetron 501 (Kerr Dental). The restorations were finished and polished using TDF finishing diamonds (Axis Dental), Politip polishers (Ivoclar Vivadent), and Occlubrush (Kerr Dental).
It was now time to prepare Laura’s teeth for porcelain laminates. The old bonding on her left canine was removed. Depth cuts were made in all the teeth to be veneered using a KaVo OPTItorque LUX 3 649B high-speed air handpiece (KaVo America) and depth cutting burs from the LVS kit (Brasseler USA). The depth cuts in the upper left canine are shown in Figure 6. Preparations were completed using the No. LVS-3 (6844-016), a 2-grit diamond with a finer grit for preparation of the margins.
It is critical that the marginal areas are captured clearly in the impression. To insure this, Ultrapak retraction cords No. 000 (Ultradent) were placed (Figure 7). Although the preparations were equigingival, the cords created space for the low viscosity impression material to flow into. A full-arch impression using Permadyne Penta (3M ESPE) as the tray material and Permadyne Garant (3M ESPE) as the wash material was made (Figure 8). The laminates were constructed on the die model. After a try-in with Prevue Try-In Gels (Cosmedent), the veneers were placed using Single Bond (3M ESPE) and Insure resin cement (Cosmedent, Figure 9).
 |
 |
| Figure 6. Depth cuts on canine. | Figure 7. Retraction cords in place, preparations completed. |
 |
 |
| Figure 8. Impression for porcelain laminates. | Figure 9. Laminates in place—facial view. |
CREATING THE ILLUSION OF PROPER SIZE
The key to correcting Laura’s asymmetrical upper arch was in using one of 4 illusions, in this case the narrowing illusion. Figure 10 shows the normal path of light reflection off the facial surface of a central incisor. If we want to make a tooth look narrower, we have to move the proximofacial line angles (highest points of contour) closer to the middle of the tooth. Figure 11 illustrates how there is a smaller area for light to reflect straight off the facial surface of an incisor, thereby making it appear narrower to an observer. Of course, this phenomenon applies to what the observer perceives from the facial or frontal view. The distofacial line angle of Laura’s upper left canine, now taking the position of her lateral incisor, was moved significantly toward the mesial, as seen in the occlusal view (Figure 12). The lateral incisor now appears narrower and allows for the appearance of proper proportion among Laura’s teeth. The post-op facial picture confirms that Laura’s new smile does in fact look symmetrical (Figure 13). It is also obvious that smiling has become more relaxed and natural for Laura.
 |
 |
| Figure 10. Normal incisor. | Figure 11. Narrowing illusion. |
 |
 |
| Figure 12. Laminates in place—occlusal view. | Figure 13. Postoperative full-face image. |
Case 2
In the second case, our patient, Goia, had maxillary asymmetry, and her smile rehabilitation was complicated even further by the presence of a gummy smile. She did not smile easily, as seen in Figure 14. She had porcelain-fused-to-metal crowns on teeth Nos. 7 to 10 (Figure 15). There was decay at the margins of the crowns. She also had large, old amalgam restorations in teeth Nos. 4 and 13 that imparted a gray color to these teeth. Goia’s maxillary asymmetry is seen in the occlusal view in Figure 16 and the diagnostic models when viewed from an incisal view in Figure 17.
 |
 |
| Figure 14. Preoperative smile attempt. | Figure 15. Preoperative retracted view. |
 |
 |
| Figure 16. Occlusal view showing asymmetry. | Figure 17. Study models showing asymmetry. |
A FEW WORDS ABOUT THE GUMMY SMILE
The gummy smile is a condition characterized by an excessive display of maxillary gingiva during smiling. A gummy smile may be present due to many factors. A short upper lip or vertical maxillary excess (a long upper jawbone) may cause someone to have a gummy smile. Gingival inflammation resulting from medications or orthodontic braces can cause a gummy smile. Another reason for a gummy smile is altered passive eruption. This phenomenon occurs when the gums do not recede to a normal level after the teeth have erupted. When a person has a parafunctional habit such as bruxism, this can cause excessive wear. If continued tooth eruption lags behind the rate of wear, the teeth will appear too short, and this may also lead to a gummy smile.
Goia had some difficulty in putting her lips together. This often happens in people with long faces and a gummy smile. Surgical correction to reposition the upper jaw in relationship to the rest of the face as described by Fowler4 may have corrected this aspect of her case, but the maxillary asymmetry would still be present. An additional method for correcting the gummy smile has recently been shown on the ABC television show “Extreme Makeover.” As described by William Dorfman, DDS, and Garth Fisher, MD, a horizontal strip of labial mucosa is excised from the inside of the upper lip and a mucosal flap is sutured to the inferior border of the excised area. This procedure was developed by Kamer and others.5-7 Goia elected not to have surgery.
Treatment Plan
The treatment plan called for removal of the existing crowns on teeth Nos. 7 to 10 inclusive. Root canal therapy and posts and cores would be completed as needed. A combination of porcelain veneers and porcelain-fused-to-gold crowns would then be used to restore her smile. The decision as to which restoration to use was based on the amount of remaining tooth structure on each tooth. Our desire was to restore what was missing and preserve as much natural tooth structure as possible.
CHAIRSIDE
The old crowns were removed by cutting slots in them using a Midwest Stylus high-speed air-driven handpiece (DENTSPLY Professional) and tapping the pieces off in sections. After removal of the crowns on teeth Nos. 7 to 10, hemostasis was obtained with the Dento Infusor and Viscostat (Ultra-dent). Root canal therapy using the Elements Apex Locator (Sybron Endo) for canal measurements and Premier K-Files (Premier Dental USA) was completed. Integra posts (Premier Dental USA) were placed in teeth Nos. 8 and 9. After etching, washing, and drying, Clearfil Photo Bond, a dual-cure bonding agent (Kuraray Dental), was placed in the post space. The posts were cemented with IntegraCem (Premier Dental USA). Core buildups were completed by injecting Luxacore Dual (Zenith Foremost) around the posts and holding Crown Forms (DENTSPLY Caulk) filled with Luxacore as matrices over the posts. Preparations were completed and temporary restorations created with PERFECTemp (Discus Dental). To give the temporaries a high surface gloss, a thin coat of Temp Glaze (clinician’s Choice) was applied and light-cured.
An impression made with Flexitime (Heraeus Kulzer) and an impression of the opposing arch made with Position Penta Quick (3M ESPE) using Originate Trays (Axis Dental) were sent to the laboratory. In addition, the undershade of the teeth to receive laminates, a bite registration, and full-face photo were sent to the laboratory. It is this author’s opinion that the full-face photo is a critical piece of information. By having this at the time of fabrication, the technician can relate to the patient on a different level than is possible through models alone. The full-face photo allows the technician to create restorations that are in harmony with the patient’s face.
 |
 |
| Figure 18. Final restorations on die model. | Figure 19. Postoperative smile—retracted view. |
The laboratory completed the restorations and attempted to minimize the right side prominence. This can be seen when comparing Figures 17 and 18. All the restorations were tried in and contact areas were adjusted using Chipless Wheels (Shofu) and CeraMaster porcelain polishers (Shofu). Veneers were cemented with Insure, and the PFM crowns were cemented with Fuji PLUS (GC America), a resin-reinforced glass ionomer cement.
The patient was evaluated post-placement for aesthetics and function. She reported being comfortable with the restorations, and the final result is seen in Figure 19. While Goia does not retract her lips fully in an upward direction when smiling, she has developed a more confident smile by retracting her lips slightly upward and laterally. This can be seen in Figure 20.
 |
| Figure 20. Postoperative full-face image. |
CONCLUSION
The 2 complex cases described above illustrate some of the challenging situations we face. Fortunately for our patients, we now have a better understanding of how to compensate for some of nature’s mishaps. It is my hope that the information presented here will help other practitioners face these challenges with greater confidence.
Traditionally, dentistry has been a profession that has restored the ravages of dental disease. From diagnosis to treating decay and periodontal disease to providing implants and prostheses, we have made enormous technical advances. Because of today’s media, patients are recognizing what many of us have always known; smile rehabilitation is not only possible, but can positively impact and change people’s lives.
Acknowledgment
Thanks to daVinci Dental Studios for its assistance in making these cases successful and to the patients for allowing their cases to be shared.
References
1. Blum D. Face it!—facial expressions are crucial to emotional health. Psychology Today. 1998;5:32-39.
2. Thornhill R, Gangestad SW, Miller R, et al. MHC, symmetry, and body scent attractiveness in men and women. Behavioral Ecology. 2003:14:668-678.
3. Garber DA, Salama MA. The aesthetic smile: diagnosis and treatment. Periodontology 2000. 1996;11:18-28.
4. Fowler P. Orthodontics and orthognathic surgery in the combined treatment of an excessively “gummy smile”. N Z Dent J. 1999;95:53-54.
5. Kamer FM. “How I do it”—plastic surgery. Practical suggestions on facial plastic surgery. Smile surgery. Laryngoscope. 1979;89;1528-1532.
6. Kostianovsky AM. The “unpleasant” smile. Aesthetic Plast Surg. 1977;1:161-166.
7. Litton C, Fournier P. Simple surgical correction of the gummy smile. Plast Reconstr Surg. 1979;63:372-373.
