Terminal dentitions often have missing teeth and altered landmarks, making the rehabilitation of such dentitions challenging. The use of facial analysis can assist in the diagnostic phase of treatment in determining the ideal anticipated incisal edge position. An understanding of facial parameters from a quantitative aspect is essential for creating youthful smiles which can in turn provide proper hard tissue support to enhance facial esthetics.
Key points
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Facial analysis should be used to enhance the esthetic outcome of an All on X restoration.
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Facial analysis can help determine the ideal anticipated incisal edge position (AIEP).
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When an ideal AIEP is achieved, the outcome results in both an esthetic smile and improved facial esthetic parameters.
Introduction
The demand for esthetics is pervasive in society. With the advent of social media, there has been an inundation of esthetic-focused procedures, from cosmetic surgery to dental makeovers. Dentistry is constantly evolving to improve esthetic results through the use of more natural-looking materials, digital processes, and a plethora of online educational courses. Fundamentally, all of these processes and venues continue to be based on the foundations of proportions and symmetry. Dental esthetics is guided by tooth form/shape, proportions, symmetry, and materials. Typically, social media displays dental esthetics as a smile from commissure to commissure or as a close-up photograph of teeth in a retracted smile. However, the influence of facial form has not been fully incorporated into the design of the smile. Although feminine and masculine tooth forms have been correlated to facial form, there remains a lack of integration of facial analyses into the dental aspects of smile design.
Full-arch restorations have the ability to not only create dental esthetics but also restore facial beauty that is often affected by missing or malpositioned teeth, as well as the facial aging processes. Soft tissue facial support declines significantly with increasing age. Premature loss of teeth, as well as malpositioned teeth, can also contribute to a lack of soft tissue facial support. Because the jaws are affected not only by aging but also by the presence of teeth and their position, this can have a substantial impact on the lower third of the face. Plastic surgery research suggests that skeletal augmentation can improve the outcomes of facial rejuvenation, as it provides a more permanent solution than the currently used soft tissue techniques. Facial aging in the absence of dental factors is characterized by a decrease in ramus height and mandibular body length and an increase in the mandibular angle. Other age-related facial skeletal parameter changes alter not only the hard tissue structures themselves but also the support of the facial soft tissue drape. , Dentistry can provide permanent hard tissue support, resulting in soft tissue support as well. Full-arch implant dentistry not only restores dental esthetics and function but can also restore facial form by applying the principles of facial esthetics in the treatment planning process.
Dental esthetic paradigms and the role of facial form
The literature is replete with various esthetic paradigms involving proportions, symmetry, materials, and tooth position. Defined originally by ancient Greek and Egyptian civilizations when referring to architecture, the concepts of proportions and symmetry have become well-established principles in the field of dentistry. Nevertheless, tooth position is perhaps the single most important aspect of a smile. A smile is designed from the position of the maxillary central incisors and dictated by the horizontal, vertical, and anterior-posterior (A-P) positions of the teeth. A beautiful dental restoration with ideal proportions, esthetic restorative design, and materials can be negated simply by malposition of the restoration. If full-arch restoration is predicated on ideal central incisor positioning, then we as clinicians should consider the X (horizontal), Y (vertical), and Z (A-P) axes of these teeth to achieve ideal positioning to enhance the facial drape of a beautiful smile. Understanding facial esthetics could govern the placement of these axes for the central incisors.
Ideal facial form, as defined by certain facial parameters in facial esthetics publications, is often ignored as a factor influencing the anticipated incisal edge position (AIEP). The AIEP dictates arch form, symmetry, and overall dental esthetics, but a beautiful dental restoration does not always result in an esthetically pleasing smile. A well-positioned smile within the frame of the lips and positioned properly in all dimensions (horizontal, vertical, and A-P) can enhance not only the smile but also the facial form. Although achieving the ideal form is not always realistic, full-arch solution dentistry should strive to improve the soft tissue drape of the face, as well as the defined esthetic proportions.
The face is an important determinant of the AIEP. Each of the 3 components of the AIEP (horizontal, vertical, and A-P positions) should be predicated on understanding the ideal facial form. The challenge is to account for the facial soft tissue drape changes that occur over time, which differ between sexes. The rate of these facial changes also differs according to age and sex. Determining the ideal AIEP that provides an esthetically pleasing restoration can be both challenging and limited by the facial aging process.
What dictates the ideal X, Y, and Z axes for central incisor tooth position? Understanding facial form and the aging process allows clinicians to devise a treatment plan for optimal esthetics whereby the teeth not only result in a beautiful smile but also enhance and/or restore the face to a more esthetically pleasing facial form. Several parameters of facial esthetics will allow the clinician to create an ideal AIEP. Two views of the face are used to determine these parameters: a frontal view and a lateral (profile) view. Frontal facial analysis can help determine the dental components of the smile: horizontal position (with respect to the midline), vertical position, and the occlusal vertical dimension (OVD). Profile facial analysis is useful for determining the A-P position of the maxillary central incisors and the lower teeth, the axial and labial inclination of the teeth, and the OVD.
The frontal view shows the facial thirds, lower facial third ratio, and incisal midline, as well as the vertical incisal edge position at repose and during maximal smiling ( Fig. 1 A–D). The profile view illustrates the Holdaway angle, nasolabial angle, labiomental sulcus, and projection of the lower lip and chin ( Fig. 2 A–D). Dentistry can modify the lower facial third by altering the OVD, which can restore the proportion of the lower facial third, thereby creating a more harmonious face. The facial thirds are measured from the trichion to the glabella, from the glabella to the subnasale, and from the subnasale to the menton. Although the overall vertical height of the lower facial third (in relation to the middle and upper facial thirds) can be improved, the lower facial third ratio, which is located within the lower third of the face, should also be considered. The lower facial third ratio refers to the distance from the subnasale to the stomion, compared to the distance from the stomion to the menton, with the ideal ratio being 1:2 (a one-third upper, two-thirds lower proportion).
Not only can full-arch dental restorations improve esthetic ratios, but they can also restore a youthful appearance to the face by restoring facial support ( Fig. 3 ). The vertical position of the teeth should be predicated on the lower facial third ratio but is also heavily influenced by lip length. Unfortunately, the aging processes of male and female lips differ significantly, necessitating a thorough understanding of normal age-related incisal display for each sex. Understanding esthetic facial design and ideals allows clinicians to formulate treatment plans with an ideal AIEP to create a beautiful smile and assist in recreating youthful facial support. Facial features influence the 3 critical positions of the AIEP, the midline (horizontal) position, the vertical position of the incisal edges, and the A-P position. OVD corrections are often necessary when rehabilitating a terminal dentition, as determining which (if not both) arch requires modifications is predicated on the ideal upper incisor position ( Fig. 4 A, B).
Frontal analysis
Horizontal Position
The horizontal position of the teeth is evaluated by aligning the midline of the teeth with the midline of the face. Facial midlines are usually dictated by the philtrum, which is often coincident with the facial midline. Midline deviations can be detected more readily by dental professionals than by the general public and, as such, are perhaps the least important of the 3 esthetic components of AIEP (ie, horizontal, vertical, and A-P) ( Fig. 5 ). However, they still contribute to the overall esthetic outcome. Facial asymmetries often result in deviations of the jaw, nose, and/or chin, which can affect the anticipated dental midline. According to the concept of “facial flow,” asymmetric faces in which dental midlines deviate along with the curvature of the face may result in a more harmonious appearance of the smile. Midline deviations typically do not indicate a lack of youthfulness, but they may be a perceived distraction to an anticipated esthetic result. Aligned facial and dental midlines do not suggest a more youthful appearance than divergent midlines. Thus, the horizontal aspect of the AIEP affects beauty and symmetry but does not contribute to a more youthful smile.
Vertical Position
Vertical position of the teeth is perhaps the most difficult aspect of smile design, as numerous factors must be considered, including symmetry of the facial thirds, the lower facial third ratio, numerous aspects of the lips, and the effects of facial skeletal aging (which differs between sexes). Evaluation of facial thirds symmetry relates to the need to restore the OVD and improve the symmetry of the lower facial third with respect to the upper and middle facial thirds. Assessment of the lower facial third ratio dictates how much adjustment of the OVD of the upper and/or lower teeth is required to achieve the ideal 1:2 ratio.
After considering the first 2 factors, the clinician should assess various aspects of the lip that are important for smile design. Understanding the various components of the lip is essential in the treatment planning process. Frontal analysis should include determination of lip length, symmetry, mobility, and volume. To restore a youthful smile, several questions are relevant. Do we clinicians understand proper lip length, which is based on sex and age, as well as understand the clinical challenges presented by deviations from the norm? Does the restoration arch form support the lip to help create lip symmetry? Is lip mobility recorded, and do we understand its impact on the esthetics of a restoration? Do age-related changes alter lip volume, or are there age-related changes that alter the lip position and shape without altering the volume?
Lip length
The length of the upper lip can be affected by soft or hard tissue developmental issues, the aging process, or excessive use of fillers. Understanding the impact of lip length on the successful appearance of an esthetic smile is essential when lip length deviates from the norm.
Numerous average lip lengths have been described in the literature, although further research is necessary to fully understand the sex-related and age-related differences in lip length. In a study by Roe and colleagues, the average lip length in females was 20.4 mm, and the average length in females with a “short” lip was 17.4 mm. In men, the corresponding averages were 22.7 mm and 19.1 mm. The mean age of participants was 27 years for both males and females in the study. Other researchers have reported similar values, and we as clinicians can use these lengths as guidelines, but it is important to remember that they do not reflect age-related changes (given the young age of the study participants). Significant changes in upper lip length that affect incisor display at rest and when smiling occur in men starting at approximately age 25 years. The redistribution of volume resulting in longer lips occurs at an older age in women. The aging female lip typically becomes evident in the sixth decade of life, and although changes in the perioral region are similar for both sexes, the changes are less pronounced in men.
Minor changes in vertical tooth position can be made to provide a more youthful appearance, but it is imperative that both the patient and clinician understand the limitations of vertical tooth position based on the lip ( Fig. 6 A–C). Restoring a youthful smile may require redistribution of lip volume in older patients. Lip length reduction procedures, possibly in conjunction with volume augmentation, should be considered in treatment planning to create a more youthful smile for both sexes. ,
Figs. 7 and 8 show the treatment approach for a patient with a long lip length. This 48-year-old female presented with a request for veneers, as she wanted to display more teeth when smiling ( Fig. 7 A, B). Incisal composites were previously placed, and her width-to-height ratio was approximately 70%, which was below the esthetic norm of 75% to 85%, yet the appearance of her teeth was relatively pleasing. She had a developmentally long lip of 25 mm, mid-face deficiency, and a history of orthodontics twice. It was determined that a lip lift procedure was the best approach to achieve the patient’s esthetic goals ( Fig. 7 C). Fat injections were injected into her upper lip to restore the anterior projection of the lip, which was required because of her mid-face deficiency ( Fig. 7 D). The patient was pleased with the final result ( Fig. 8 A–D).
