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Designing and achieving a natural and esthetic smile for our patients can be one of the most rewarding things we can do as restorative dentists. An analysis of a beautiful smile can begin from the outside in; or in other words, starting with the anatomy of a smile and how the smile fits within a patient’s face. This generalized perspective of a smile and its analysis is related to global esthetics. As we narrow the analysis of the smile we study the shapes and contours of teeth, or macro esthetics.1 The analysis can be narrowed more by reviewing the micro esthetics, the criteria related to the subtle intricacies of shade, texture, translucency, and surface effects that make teeth look like teeth. Some authors also use a fourth category of smile analysis, gingival esthetics.2 This article will focus on the analysis of maxillary incisal edge position as a part of the global esthetics of a smile. It will also focus on the importance of using diagnostic photography and provisional restorations to achieve an esthetic and functional maxillary incisal edge position.
High-quality digital photos are useful in assessing maxillary incisal edge position, midline placement, gingival contours, buccal corridor, and other esthetic and functional considerations. Quality digital photography, when used in conjunction with a diagnostic wax-up and provisional restorations, are important aids in finding a natural maxillary incisal edge position. Photos can be used to assess the patient’s current incisal edge position and then create an estimated position by waxing it onto a set of properly mounted diagnostic models. The waxed incisal edge position can then be transferred to the patient’s mouth in provisional restorations and another set of diagnostic photos taken to confirm the proper placement of the incisal edge. Adjustments to the provisional restorations are easy to make as the restoring dentist and patient analyze the new position. Models of the patient-approved provisionals can be made and used to transfer this desired maxillary edge position to the lab for creation of the final restorations in the exact location of the provisional restorations. After delivery of the final restorations, another set of photos can be taken to record the final incisal edge position.
Six photos are essential for achieving esthetic and functional incisal edge position. These six photos are not a comprehensive list of photos used to analyze a patient’s smile, but rather used to analyze the maxillary incisal edge position. These photos include a full-face smile photo, close-up smile photo, rest-position photo, exaggerated “E” photo, tip-down smile photo, and profile smile photo.
Full-Face Smile Photo
The full-face smile photo is beneficial in determining the proper midline and assessing for any facial asymmetries that may affect the smile. Midline is very challenging to determine from a close-up smile photo, as the smile may be deviated from the midline of the face, producing an inaccurate facial midline. Therefore, a full-face smile photo is the best photo to use to determine the correct midline.
The facial midline can be used as the starting point of esthetic smile design.3 A correctly placed facial midline is critical for the success of a natural looking outcome. However, some confusion remains regarding the best techniques for reliably locating the facial midline.4 The full-face smile photo is important to record the prominent facial anatomy, but even using these facial landmarks can be deceptive in determining proper midline placement. Many people have facial anatomy (eg, noses and chins) that deviate from the midline, which diminishes the reliability of using the nose and chin as the only landmarks in assessing midline placement.5
One approach to obtaining a proper maxillary midline is to draw a line between the nasion (center point between the eyes and inferior to the eyebrows) and the center of the philtrum (cupid’s bow) of the upper lip (Figure 1). Miller and colleagues examined 500 natural dentitions and found that for reconstructions of fully edentulous jaws the most reliable way to find the midline was to use the facial midline directed by the philtrum.6 Extending this line through the smile zone will give a very good starting position for the proper position of the maxillary midline. The maxillary midline should be parallel to the facial midline, perpendicular to the incisal plane, and perpendicular to the interpupillary line. Interestingly, studies show that a deviated maxillary midline of up to 4 mm may not be deemed unesthetic. However, a canted midline of only a few degrees is objectionable.7-9 An accurate facebow and mounting of quality diagnostic models will help prevent canted anterior restorations. The midline should also drop straight down from the papillae between the maxillary central incisors.1
Close-Up Smile Photo
The close-up smile photo assesses the smile line, lip line, buccal corridor, average lip mobility during average smiling movements, and maxillary incisal edge position. It is important to understand the difference between the smile line and the lip line.
The smile line, an imaginary line traced along the incisal edges of the maxillary anterior teeth, should mimic the curvature of the superior border of the lower lip while smiling (Figure 2).1,10,11 Considerations should be made when asymmetric lower lips are noted and the clinician should make adjustments to smile design when such asymmetries are present.12 When normal lower lip anatomy is noted, the maxillary lateral incisors are offset from the central incisors by 1 mm to 1.5 mm.13 The maxillary canines will also be slightly longer than the lateral incisors, but slightly shorter than the maxillary central incisors. This will still provide an esthetic curvature of the incisal edges that mimics the superior border of the lower lip while smiling. A reverse smile line can occur when the incisal edges of the canines are longer than the incisal edges of the central incisors.2 Beware of the reverse smile line as this is not esthetic and shows an aging dentition, and should be avoided when restoring a smile. The goal of maxillary incisal edge position is to have the incisal edges rest lightly on or near the inner vermillion of the lower lip, which will be discussed further in the tip-down smile photo and profile smile photo section of this article.
The lip line refers to the position of the inferior border of the upper lip and thereby determines the display of either tooth or gingiva at the upper border of the smile. In a youthful smile, 70% to 100% of the maxillary incisors should be visible and exposed by the upper lip.10,14 High smile lines may show the entire facial surface of the maxillary incisors and a considerable amount of gingival architecture.
The shape and size of the lips outline the esthetic zone, forming a frame that displays the teeth and various amounts of gingiva.15 It is the restoring dentist’s responsibility to ensure the anterior maxillary teeth are placed appropriately within this soft tissue framework to provide a natural appearance and appropriate function.
Rest-Position and Exaggerated “E” Photos
The rest-position photo and exaggerated “E” photo help determine the proper length of the maxillary incisors. The rest-position photo shows how much incisal edge displays when the lips are at rest and open in a natural relaxed position. An aged, worn dentition may not show any maxillary incisal edge in this rest position. However, a youthful dentition will show 2 mm to 4 mm of incisal edge when in the rest position (Figure 3).16 Taking this photo can be a bit tricky. Asking the patient to lick his/her lips, swallow, and then just let their lips fall open is one technique to produce a predictable rest-position photo.
The exaggerated “E” photo is also used to help guide the restoring dentist to approximate maxillary incisal length and assess the potential hypermobility of the upper lip. The exaggerated “E” photo uses a measurement from the maxillary lip line to the mandibular lip line as a guide to where the maxillary incisal edge position should be placed. A good guideline for appropriate length on this photo is that the maxillary incisal edge lays 50% to 70% from the inferior border of the maxillary lip line to the superior border of the lower lip (Figure 4).17 The “E” photo is taken by asking the patient to say “E” and giving an exaggerated smile. The teeth should be apart and not occluding when this photo is taken.
Some patients find this photo challenging because they may not want to show their maxillary teeth as they may be embarrassed by their existing smile. The dentist or assistant taking this photo should recognize this before they take the photo and ensure the patient understands the instructions. Practicing before any photo is taken is beneficial in most situations.
The exaggerated “E” photo can help the restoring dentist assess the amount of gingival display when the patient gives their largest smile possible. It will also assist the dentist in assessing a potential hypermobile upper lip. Knowing the existence of, or lack of, a hypermobile upper lip will bring confidence to the restoring dentist that the maxillary incisors are in the correct position within the smile zone. An average upper lip will typically move 8 mm to 10 mm in full smile.18
Tip-Down Smile Photo
The tip-down smile photo will help the restoring dentist assess the maxillary incisal edge in relation to the lower lip on a horizontal plane. This photo is taken from a 45° angle from the occlusal plane.1 The tip of the nose is typically in this photo, but if the nose blocks the view of the incisor then the photo was taken at too steep of an angle. The purpose of taking this photo is to analyze the incisal edge position compared to the lower lip. It will assist the restoring doctor in balancing the function and esthetics of the maxillary incisal edge position.18 The maxillary incisal edge should land on, or point towards, the vermilion border (wet/dry line) of the lower lip (Figure 5). If the incisal edge is too buccal, then it will land on the dry tissue of the lower lip and can lead to the restorations feeling “bucked” to the patient. This can also lead to phonetic concerns.
Profile Smile Photo
The profile smile photo is also used to assess the incisal edge position in a horizontal plane. This photo is taken from the side of the patient and should not be tipped down or up, thus allowing an adequate view of where the incisal edge contacts the lower lip. Again the vermilion border of the lower lip is the desired target point and is a landmark within the facial tissue to estimate maxillary incisal edge position. If the maxillary incisal edge does not touch the inner vermillion border then it should at least point towards the vermillion border (Figure 6). Leaving the incisal edge position too lingual can potentially lead to an impingement on the envelope of function, resulting in potential distalization of the mandible, excessive wear of the mandibular incisors, and excessive wear of the lingual of the maxillary incisors.
A common mistake is to leave the incisal edge on provisional restorations too far buccal to the vermillion border. Adjusting the incisal facial plane and “tucking it” into the lower lip can often correct this, moving the incisal edge lingually and providing a more natural esthetic result. This typically will still allow for proper function.
Phonetics can also play an important role in analyzing maxillary incisal edge position. When the patient says the “F” sound, the maxillary incisal edges should not indent the lower lip. If dimpling of the lower lip is noted, it may mean the maxillary incisal edges are too long.1 This phonetic test should be used in a natural manner and not ever forced.
Conclusion
The use of quality digital photography, a diagnostic wax-up, and provisional restorations are important aids to help locate and determine incisal edge position. Quality before-treatment photos provide significant information about incisal edge position, including the six key digital photographs discussed in this article. The before-treatment photos can be used to assist in the diagnostic wax-up and proper placement of the maxillary incisal edge position in three-dimensional space and then transferred to provisional restorations in the patient’s mouth. These provisional models can be adjusted and another set of photos taken to confirm proper placement of maxillary incisal edge position. This desired incisal edge position is then communicated to the lab and recreated in the final restoration. Following the guidelines in this article for analyzing the maxillary incisal edge position can give the restoring dentist confidence that the final maxillary incisal edge position is in the correct location within the patient’s smile.
Disclosures
The author has no relevant financial relationships to disclose.
References
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About the Author
V. Landon Blatter, DMD
President
Rocky Mountain Dental Partners
Denver, Colorado
