Tooth show enhancement in the esthetic zone: a review and proposal a decision-making framework

Abstract

This article aims to comprehensively review the clinical indications for esthetic crown lengthening (CL) and to propose a decision-making framework that incorporates key yet often overlooked factors influencing treatment planning. To gain a deeper understanding of the various clinical scenarios in which esthetic CL may be indicated, individual conditions are examined in detail, each accompanied by an appropriate treatment approach. Based on this analysis, we introduce a decision-making framework designed to guide clinicians in selecting the optimal treatment modality by accurately identifying the underlying esthetic concerns. The majority of published clinical guidelines for esthetic CL focus predominantly on cases with excessive gingival display. However, patients presenting without gingival display who may still benefit from esthetic CL are frequently neglected in the literature. Additionally, the influence of the smile arc and its relationship to incisal edge positioning remains underrepresented in current discussions. Our proposed decision-making framework integrates these critical factors to support more individualized and comprehensive treatment planning. Clinicians must possess a thorough understanding of all relevant esthetic and functional parameters when evaluating candidates for esthetic CL. Moreover, early and coordinated consultation with the prosthodontist is essential to define the appropriate balance between surgical and restorative interventions prior to surgical execution.

Introduction

Smile esthetics

With the modern advancements in digital smile design, pleasing smile esthetics has become increasingly important for both clinicians and patients (Alharkan 2024). The amount of anterior teeth visibility plays a crucial role in facial esthetics appeal (Springer et al. 2011). From an esthetic perspective, several key factors significantly affect the visual appeal of a smile. A harmonious smile includes having at least two-thirds of the length of the anterior teeth visible when smiling, aligning smoothly with the smile arc, and following the natural curve of the incisal edges. A straight facial and dental midline, a proportional width-to-length ratio for anterior teeth, and 1–2 mm of gingival display are also essential for achieving smile harmony and esthetic balance. Any absence or compromise of these factors can lead to a smile that strays from the ideal, negatively affecting one’s self-image and overall satisfaction with their appearance (Chiche and Pinault 1994; Machado 2014).

An ideal smile is characterized by the full display of the maxillary incisors along with 1–2 mm of gingival tissue (Monaco et al. 2004). In the context of gingival display, excessive and insufficient gingival display represent two extremes of a continuum, both of which are esthetically unpleasing. Excessive gingival display (EGD), or a gummy smile, occurs when more than 3 mm of gingival tissue is visible when smiling (Pavone et al. 2016). On the other hand, inadequate tooth show and gingival display resemble a more elder appearance, which often causes esthetic concerns in patients (Perenack 2005; Dym and Pierre 2020).

Etiology of unaesthetic smiles

Achieving a balance is crucial for attaining an esthetically pleasing appearance, as both extremes can adversely affect the harmony of the smile. Various etiological factors can lead to EGD, including altered passive eruption, maxillary vertical excess, dentoalveolar extrusion, gingival overgrowth/enlargement, a short upper lip, and hypermobile upper lip. One or multiple factors may contribute to the development of a gummy smile (Robbins 1999). Therefore, an accurate diagnosis is necessary in order to identify the etiology and consequently tailor an appropriate treatment plan according to the patient’s clinical profile.

The most common reason for patient referral for cosmetic procedures continues to be inadequate tooth visibility due to the presence of a gummy smile. However, other conditions such as a low lip line, thick lips, or physiological senile changes in lip architecture, either alone or accompanied by other factors, such as short crown height, may still prompt the patient to seek cosmetic treatment. Despite their significance, the mentioned factors are often neglected. Reduced clinical crown height may also be a result of genetic factors or physiological or pathologic tooth wear (Chu et al. 2004; Venugopal et al. 2024).

Esthetic crown lengthening surgery is generally considered a straightforward procedure and has been associated with a low incidence of complications, however challenges persist in diagnosing the underlying causes of patient issues (Ser Yun et al. 2019). Despite numerous reports of treatment stability after this procedure, determining whether surgery is the appropriate solution for the patient's condition remains complex due to the multifactorial nature of the problem. Factors such as tooth length, gingival display, smile harmony, and lip position influence an individual's perception of an attractive smile.

To address the need for a more comprehensive clinical guide, this article presents a structured decision-making framework that extends beyond the commonly discussed scenarios involving excessive gingival display. While existing literature and flowcharts often focus exclusively on patients with a “gummy smile”, our proposed approach encompasses a broader spectrum of esthetic concerns, including patients without excessive gingival display who may still benefit from crown lengthening procedures. This inclusive framework aims to support clinicians and to ensure accurate diagnosis and development of an optimal treatment plan tailored to each patient's specific needs.

Methodology

Search strategy

A comprehensive search was conducted by searching electronic databases via PubMed, Medline, Embase, Web of Science, Scopus and Google Scholar. The search utilized keywords such as “gingival display,” “esthetic zone,” “crown lengthening,” “gummy smile,” and “gingival overgrowth” to retrieve relevant articles. Articles that were published from inception until March 2025 in English language were retrieved.

Clinical scenarios

Patients with excessive gingival display (Fig. 1a)

Fig. 1.

a: patient with excessive gingival display. b: patient with EGD and without VME and gingival overgrowth, who shows APE. c: patient with EGD and without VME, gingival overgrowth, and APE

A gummy smile can result from various etiologies, including gingival overgrowth, altered passive eruption (APE), vertical maxillary excess (VME), dentoalveolar extrusion, a short or hyperactive upper lip which are explained herein. Treatment planning must consider these factors in order to ensure predictable and esthetically pleasing outcomes.

Gingival enlargement/overgrowth

Gingival enlargements can be classified as inflammatory, drug-induced, associated with systemic condition or diseases, neoplastic, or hereditary conditions based on their etiopathogenesis. Each situation requires a distinct treatment approach, hence accurate diagnosis of these lesions is crucial for effective management (Agrawal 2015).

1. Inflammatory gingival enlargement, primarily caused by bacterial plaque, is the most frequent type of gingival overgrowth and is the simplest to treat. It typically ameliorates with scaling, root planing, and better oral hygiene practices (Chesterman et al. 2017).

2. Drug-induced gingival overgrowth (DIGO): gingival enlargement has been listed as one of the common side effects of many drugs including, immunosuppressants (cyclosporine A), calcium channel blockers (nifedipine), and anticonvulsants (phenytoin) (Hassell and Hefti 1991). DIGO typically occurs in the anterior gingivae (Hassell and Hefti 1991). The clinical appearance of this condition usually consists lesions with a granular or pebbly surface which may coalesce to form lobules and in some cases, this may partially cover the clinical crown (Heasman and Hughes 2014). Local factors such as plaque accumulation can exacerbate DIGO. The most effective treatment for DICO is to discontinue or substitute the current prescribed medication (Khocht and Schneider 1997). Nonsurgical treatment addresses the inflammatory component of DIGO (Kantarci et al. 1999). Surgical removal of DIGO lesions involves gingivectomy and gingivoplasty, which reduce biofilm accumulation (Ilgenli et al. 1999). Consequently, it is the preferred treatment for DIGO after phase I periodontal treatment. Maintenance should include oral hygiene instructions, periodontal prophylaxis, and calculus removal as needed (Ilgenli et al. 1999).

3. Gingival enlargement associated with a medical illness such as leukemia, sarcoidosis and granulomatosis with polyangiitis formerly knows as Wegner’s granulomatosis (Beaumont et al. 2017). In such cases, medical treatment typically alleviates gingival manifestations, often reducing or eliminating the need for dental intervention. For example, patients presenting with granulomatosis conditions require immediate care and should visit a medical specialist, therefore the timely referral by the dental practitioner is of utmost importance (Chesterman et al. 2017).

4. Gingival Enlargement associated with specific systemic conditions like puberty, pregnancy, or malnutrition. These conditions are transient, and spontaneous resolution may occur over time by assuring the control of local factors. Vitamin C deficiency might require dietary advice or supplements (Chesterman et al. 2017).

5. Familial or hereditary gingival enlargement, such as hereditary gingival fibromatosis (Livada and Shiloah 2012). depending on the severity of the condition, treatment may require conventional gingivectomy, flap procedures, or resective osseous surgery (osteoplasty and osteotomy) (Shadab et al. 2024).

As previously mentioned, the treatment of gingival overgrowth involves identifying and addressing the underlying cause, and it usually does not require surgical procedures such as crown lengthening alone (Fig. 1a).

Vertical maxillary excess (VME)

Maxillary excess refers to the vertical overgrowth of the maxillary bone, creating a stretched look to the lower facial region. A higher-than-normal gingival exposure is due to a lower-than-anticipated occlusal plane (Venugopal et al. 2024). The lower lip's position over the upper canines and premolars' biting edges is often indicative of this condition.

Cephalometric analysis can assist in identifying vertical maxillary excess (VME). Patients with VME often present with a skeletal Class II relationship. In most cases, moderate to severe VME requires orthognathic surgery as part of the treatment approach (Fig. 1a). Hence, addressing this issue necessitates highly synchronized treatment planning and implementation of both orthodontic and surgical interventions (Yadav et al. 2014). Although orthognathic surgery generally yields predictable and stable outcomes, concerns regarding the greater morbidity rates may lead some patients to forgo this treatment option. In these patients the upper lip may seem extremely short (incompetent lips) while its actual length is within the normal range (Silberberg et al. 2009). In cases with mild VME, alternative treatment options such as esthetic crown lengthening and lip repositioning surgery should be entertained (Dym and Pierre 2020). These alternative approaches can help achieve the patient’s overall desires while still maintaining realistic expectations (Ezquerra et al. 1999, Rosenblatt and Simon 2006).

Altered passive eruption (APE)

The dentogingival unit is typically situated near the cementoenamel junction (CEJ), with the gingival margin slightly overlapping the edges of the crown (Alpiste-Illueca 2012). Although not all physiological situations display this morphological disposition, the gingival margin often takes on a more incisal position, resulting in shorter clinical crowns. This variation in typical morphology, which involves a more coronal periodontium, is referred to as altered passive eruption (APE) or delayed passive eruption (Alpiste-Illueca 2011). APE is the consequence of failed gingival complex apical migration, and its most obvious (prominent) sign is the short appearance of teeth (Verardi et al. 2016).

Coslet et al. (1977) divided APE into two morphological types based on the location of the mucogingival junction relative to the bone crest, and further considered two subtypes in relation to the position of the bone crest in comparison to the cementoenamel line.

• Type 1A: The mucogingival junction (MGJ) is situated apically relative to the CEJ and the buccal bone crest. The distance between the CEJ and the alveolar bone crest is physiological for the attachment of connective tissue fibers.

• Type 2A: The MGJ is located coronal or at the CEJ. The distance between the CEJ and the alveolar bone crest is physiological for the attachment of connective tissue fibers.

• Type 1B: The MGJ is situated apically to the CEJ and the buccal bone crest. The alveolar bone crest resides at or coronal to the CEJ, which eliminates the physiological space for the attachment of connective tissue fibers.

• Type 2B: Both the MGJ and the alveolar bone crest are positioned at or above the CEJ, resulting in a lack of adequate space for the attachment of connective tissue fibers.

Patients with APE require Esthetic Crown Lengthening (ECL) surgery to reduce gingival display. However, in order to obtain optimal treatment outcomes, additional factors such as the anatomical crown length and the incisal line relative to the smile arc must also be evaluated.

In cases with excessive gingival display along with APE, two clinical scenarios can occur (Fig. 1b).:

• I.APE with a normal anatomical crown length: In this case, ECL alone is usually sufficient. By repositioning the dentogingival unit in a more apical position and exposing the portion of the crown beneath the coronally positioned periodontium, gingival display is reduced, and the clinical crown length is increased, significantly improving the patient’s condition.
• II.
  APE with a short anatomical crown length: In this scenario, in addition to ECL, adjunct restorative treatments may be necessary for optimal results. One important factor to assess is the incisal line:

  • If the incisal line follows the smile arc and is normal, esthetic veneers along with ECL can be used to increase tooth show and achieve the standard clinical crown length, but cementum exposure and the resulting reduction in bond strength remains a clinical challenge. If the patient is not willing to receive veneers, ECL alone can expose the existing anatomical crowns and reduce gingival display. If excessive gingival display persists and the final result is suboptimal, adjunctive treatments such as Botox injections or lip repositioning surgery may be considered.
  • If the incisal line is disharmonious to the smile arc, and the short crowns are due to causes such as tooth wear or fractures, restorative treatments should be employed to restore the clinical crown. In addition, ECL surgery should be performed to further ameliorate the patient’s gingival display.

The surgical technique that is employed for crown lengthening depends on the type of APE and the possible inclusion of restorations accompanying the intended perioplastic surgery. In APE type 1 A, a gingivectomy alone is sufficient, while for type 1B, additional ostectomy and osteoplasty is required for creating adequate space for supracrestal attachments. On the other hand, in APE type 2, an apically positioned flap (APF) is needed because gingivectomy would remove too much soft tissue, leaving less than 3 mm of keratinized tissue width after surgery. In type 2 A, APF alone and in type 2B, APF with osseous resection is required. To provide the necessary space for supracrestal attachment (3 mm), if no restorative treatment is planned in the cervical region of the tooth, the distance from the CEJ to the bone crest is considered. However, if a restoration is needed in the cervical area, the distance from the cervical margin of the restoration to the bone crest should be considered to prevent biologic width violation (Al-Harbi and Ahmad 2018).

Dentoalveolar extrusion

Anterior dentoalveolar extrusion is the over-eruption of maxillary incisors, leading to excessive gingival display due to higher gingival margins. Tooth wear and anterior deep bite can contribute to compensatory incisor over-eruption which is also known as active secondary eruption or dentoalveolar compensation, leading to gingival margin malalignment together with short clinical crown length (Ahmad 2017). Deep bite cases typically exhibit discrepancy between the anterior and posterior occlusal planes (Silberberg et al. 2009). Orthodontic therapy can effectively treat gummy smiles caused by dentoalveolar extrusion (Kokich 1996).

Correcting excessive gingival display due to dentoalveolar extrusion can be achieved through periodontal surgery or, alternatively, using orthodontic intrusion. This treatment modality is often followed by restorative or prosthetic procedures to compensate for lost enamel and dentin, depending on whether the underlying cause is tooth structure loss or unopposed antagonists (Ahmad 2017).

In patients with excessive gingival display without APE, one possible etiology could be dentoalveolar extrusion. In these cases, the anatomical crown length of the teeth is reduced due to tooth wear (Fig. 1c). The treatment plan includes regaining the interocclusal space required for restoring the teeth with laminates or veneers, alongside periodontal surgery for correcting misaligned gingival margins. If EGD is still present, Botox injections and lip repositioning surgery can be used to improve results.

Hyperactive upper lip

In cases where no dentoalveolar abnormalities exist, an upper lip movement greater than 8 mm is described as hyperactive (Robbins 1999). Treatment approaches are primarily at restricting the function of the elevator muscles and can involve the administration of Botox type A (BTX-A), hyaluronic acid injections, lip repositioning surgery, myotomy, or a combination of these methods. BTX-A is frequently used to treat clinical conditions with muscle hyperactivity including dental ailments driven by muscular actions such as temporomandibular disorders, bruxism, clenching, and masseter hypertrophy, as well as in cosmetic cases such as pronounced nasolabial folds, elevated lip lines, and black triangles between teeth (Nayyar et al. 2014). Owing to its easy application, minimally invasive nature, efficacy, and cost-effectiveness; the injection of BTX-A has become a favorable treatment option for the neuromuscular correction of a gingival smile (Mazzuco and Hexsel 2010).

In patients with a gummy smile resulting from minor VME or upper lip hypermobility, lip repositioning surgery can also be considered as a possible treatment option. This surgery reduces the depth of the vestibule, which in turn limits the pull of the muscles and minimizes the amount of gingival display when smiling. Additionally, this procedure can be performed alongside crown lengthening or gingivectomy (Bynum 2016; Venugopal et al. 2024) (Fig. 1b and c).

Short upper lip

In some cases, when smiling a short upper lip may fail to sufficiently cover the gums. The ideal upper lip length comprises approximately one-third of the lower facial height. The average length of the upper lip in young adults ranges from 20 to 24 mm and tends to increase with age (Jorgensen and Nowzari 2001).

The clinical length of the upper lip is determined by measuring the distance from the subnasal (point) to the lower margin of the upper lip or the stomium. If this measurement is less than 20 mm, the upper lip is typically categorized as short (Venugopal et al. 2024; Brizuela and Ines 2025). A short upper lip of non-skeletal origin can be corrected through lip repositioning surgery including elevator muscle detachment and limiting their retraction activity (Rao et al. 2015; Diaspro et al. 2018). However, severe VME and limited zone of attached gingiva contraindicates this surgery. Another option to address this condition is the intramuscular administration of BTX-A, which induces temporary paralysis of the upper lip elevator muscles, resulting in a relative increase in upper lip length and a reduction in excessive gingival display (Polo 2008).

.Patients without excessive gingival display

Attaining proportional tooth dimensions and morphology is a crucial factor in achieving satisfactory outcomes in esthetic treatments. Depending on their condition, patients without a gummy smile may also be candidates for esthetic crown lengthening surgery. The clinician should be ready to tackle two different challenges in such cases. The first challenge is inadequate gingival display that can be due to reasons such as a low lip line or thick upper lips. The second challenge is correcting the dispropo n rtional tooth size which may be caused by APE, tooth wear, short anatomical crowns or combination of the mentioned factors (Chu and Hochman 2008).

In patients presenting with inadequate tooth and gingival display, subnasal lip lift can improve their esthetic appearance by increasing the visibility of the vermilion and approximately 3 mm of tooth display at rest. However, additional surgical and restorative treatments may be necessary to achieve optimal results. Conducting a thorough initial examination and establishing and accurate diagnosis of the patient’s problems are essential of developing a comprehensive treatment plan.

If APE is accompanied by inadequate gingival display, esthetic crown lengthening surgery should be performed to increase tooth exposure and improve smile esthetics. In such cases, two clinical scenarios may arise (Fig. 2a):

• If the anatomical crown length is sufficient, the combination of ECL and subnasal lip lift surgery is usually enough to achieve the desired outcomes.

• If the anatomical crown height is short, restorative treatments should be considered in addition to ECL and subnasal lip lift surgery. In such cases, the presence or absence of attrition and possibility of incisal edge lengthening due to patient’s static and dynamic occlusion must be meticulously evaluated. If feasible, restorative procedures may be implemented to restore and extend the incisal edges, ensuring both ideal esthetics and proper function.

Fig. 2.

a: patient without adequate gingival display, with APE. b: patient without adequate gingival display and APE

The main treatment modality in patients with insufficient tooth and gingival display, is subnasal lip lift surgery (Fig. 2b).

• If the anatomical crown length is sufficient, subnasal lip lift surgery alone is usually enough to resolve the issue.

• If the anatomical crown is short, additional restorative treatments may be required to enhance tooth display, depending on the patient’s preference and the presence or absence of incisal wear.

Summary of the step-by-step clinical decision-making pathway

This study proposes a practical guideline for selecting appropriate treatment modalities in cases requiring tooth show enhancement in the esthetic zone, ranging from simple to complex scenarios. Patients presenting with insufficient tooth display were categorized into two groups based on the presence or absence of EGD (see Fig. 1a, b and c for EGD; Fig. 2a and b for non-EGD cases).

In patients whose chief complaint is excessive gingival display, the first step is to rule out VME and gingival overgrowth (Fig. 1a). VME typically requires orthognathic surgery, while the management of gingival overgrowth depends on identifying its etiology—whether drug-induced, hereditary, or otherwise—as treatment is guided by the underlying cause (Fig. 3).

Fig. 3.

Chronic inflammatory gingival overgrowth in a patient undergoing orthodontic treatment

After excluding these two etiologies, patients with EGD should be further evaluated for the presence of altered passive eruption (APE). In cases where APE is identified (Fig. 1b), the next step is to assess the anatomic crown height using standardized parallel radiographs. If the crown height is within normal limits, esthetic crown lengthening (ECL) is often sufficient. However, if the results are suboptimal, additional procedures such as lip repositioning or botulinum toxin (Botox) injections can be considered to limit upper lip mobility during smiling.

For patients with short anatomic crowns, it is essential to determine whether the incisal edge is harmoniously aligned with the smile line. When feasible, achieving the standard crown height may involve a combination of ECL and restorative procedures such as veneers or laminates to lengthen the incisal edge (Figs. 4 and 5). In such cases, digital smile design can be employed to assess the desired amount of incisal augmentation following laminate restorations, determine the required apical displacement of the gingival margin, and plan a precise surgical guide. This approach facilitates a more accurate and predictable surgical procedure, ensuring optimal integration with the planned restorative treatment (Fig. 6).

Fig. 4.

Esthetic crown lengthening in a patient with altered passive eruption and reduced incisal edge height, to be subsequently augmented with veneers

Fig. 5.

The same patient after placement of composite veneers to achieve harmonious alignment of the incisal edges with the smile line

Fig. 6.

Digital smile design for a patient with excessive gingival display, facilitating the fabrication of a surgical guide to help the surgeon determine the ideal gingival zenith based on the planned laminates for correcting the smile line

In cases where incisal edge augmentation is contraindicated, and ECL alone would expose the cementum, patients should be informed about the limitations of bonding to cementum and the necessity of restorative treatment to achieve an esthetically acceptable outcome. If the patient declines restorative procedures, only the available crown height should be exposed via ECL, followed by adjunctive options like lip repositioning or Botox.

In cases of EGD without APE (Fig. 1c), anatomic crown height should again be assessed. If crown height is normal, lip repositioning (Fig. 7) or Botox (Fig. 8) are the only appropriate interventions, as ECL would expose the cementum and create an over-elongated crown, compromising esthetics. If crown height is reduced, the clinician must evaluate whether the case involves attritional tooth wear. Many attritional cases present with compensatory dentoalveolar extrusion and accompanying EGD. In such cases, retrieval of interocclusal space followed by crown height restoration through prosthetic treatment is advised (Fig. 9). For non-attritional cases, treatment should be tailored based on the patient's smile dynamics and preferences. A combination of ECL, restorative procedures (e.g., laminates or veneers) and/or lip repositioning/Botox, may be required to achieve optimal esthetic results.

Fig. 7.

Patient with excessive gingival display and normal anatomic crown height, without altered passive eruption. (a) Preoperative view. (b) Surgical removal of a band of alveolar mucosa with partial-thickness myotomy to reduce vestibular height and limit upper lip elevation. (c) Two months postoperative view. (d) Gingival display during smiling before surgery. (e) Reduced gingival display during smiling after surgery

Fig. 8.

Patient with excessive gingival display and normal anatomic crown height, without altered passive eruption. Botulinum toxin injection reduced the upper lip elevation during smiling, resulting in decreased gingival display

Fig. 9.

Patient with severe attrition, dentoalveolar protrusion, and loss of occlusal stops. The treatment plan included interocclusal space retrieval, recreation of posterior stops, functional crown lengthening, and placement of full-coverage crowns

In patients without gingival display, tooth show enhancement may still be a clinical concern (Fig. 2a and b). The diagnostic and treatment steps follow a similar protocol as in cases with excessive gingival display. The first step is to assess the presence or absence of altered passive eruption (APE).

If APE is present (Fig. 2a), the next step is to evaluate the anatomic crown height to determine whether it is within normal limits or shortened. In patients with normal anatomic crown height, esthetic crown lengthening (ECL) can be performed to establish the ideal gingival architecture, followed by a subnasal lip lift procedure to enhance tooth show during smiling.

In cases with short anatomic crowns, the clinician must determine whether the reduced crown height is due to attrition. If attrition is the underlying cause, interocclusal space retrieval, ECL, and restorative treatment (e.g., veneers or full-coverage restorations) should be performed. Subnasal lip lift may be considered as an adjunct to improve the esthetic outcome.

In non-attritional cases, the feasibility of increasing tooth height must be assessed based on anterior guidance and the patient's smile line. If increasing crown height is feasible, ECL followed by restorative procedures (laminates or veneers) can be performed. Subnasal lip lift may again be considered to optimize results. If crown height augmentation is not feasible, ECL combined with a subnasal lip lift may offer the best esthetic improvement without compromising function.

On the other hand, in patients without gingival display and without APE (Fig. 2b), the treatment strategy again begins with determining whether the anatomic crown height is normal or short. Management in these cases typically involves subnasal lip lift (Fig. 10) either alone or in combination with restorative procedures. In cases of attrition, interocclusal space retrieval should be incorporated into the treatment plan to facilitate functional and esthetic rehabilitation.

Fig. 10.

Subnasal lip lift surgery in a patient presenting with the chief complaint of reduced tooth display

As demonstrated in the clinical cases, some patients require more than esthetic crown lengthening alone, while others need entirely different management approaches. An incorrect diagnosis or treatment choice can worsen esthetic and functional outcomes. This framework helps clinicians evaluate each case step by step, ensuring accurate etiologic assessment and selection of the most appropriate treatment combination for predictable and stable results.

Conclusion

Appropriate amount of gingival display, contour, and morphology, along with the color, shape, and position of the teeth and lips, all play a crucial role in smile esthetics. Any discrepancy in tooth and gingival display, whether in the form of excessive gingival display or insufficient tooth and gingival exposure while smiling, can negatively impact one’s smile. The etiologic factors contributing to these conditions include both soft and hard tissue abnormalities, which may occur solely or simultaneously, making diagnosis and treatment planning complex for each case.

The proposed treatment approaches, include:

• Orthognathic surgery for patients with major skeletal discrepancies.

• Periodontal esthetic crown lengthening for patients with APE.

• Lip repositioning surgery or botax for patients with a short or hyperactive upper lip.

• Subnasal lip lift surgery for patients with a long or thick upper lip.

These treatment modalities are often employed in conjunction with each other and are supplemented by adjunct restorative procedures to achieve optimal esthetic outcomes.

Authors contributions

Moein Khojasteh conceptualized the study and designed the decision-making flowcharts. Rumina Najafi drafted the initial manuscript. Farid Shiezadeh contributed to manuscript writing and performed critical editing. Zahra Moslehitabar revised the second draft and redesigned the flowcharts. Zahra Shooshtari was involved in writing and manuscript editing. All authors read and approved the final version of the manuscript.

Funding

The authors received no financial support for the research, authorship, and publication of this article.

Data availability

Not applicable.

Declarations

Ethics approval

Not applicable.

Consent for publication

Written informed consent was obtained from all patients included in this study for the publication of their clinical images. All patients were informed that their images would be used in a scientific publication and that anonymity would be maintained.

Competing interests

The authors have no relevant financial or non-financial interests to disclose.