Image

Annali di Stomatologia | 2026; 17(3): 601-611

ISSN 1971-1441 | DOI: 10.59987/ads/2026.3.601-611

Articles

The science of a radiant smile: toward a systematic review

Paola Bassi1, Gregorio Menozzi2,3, Guido Galbiati3, Chiara Dini3, Paolo Cressoni2, Alessandra Laforgia1, Sabina Saccomanno4, Maral Di Giulio Cesare1, Claudia Ciocia1, Andrea De Giacomo1, Franceska Vinjolli5, Edit Xhajanka6

1Department of Interdisciplinary Medicine, University of Bari “Aldo Moro”, Bari, Italy

2Department of Biomedical, Surgical and Dental Sciences, School of Dentistry, University of Milan, Milan, Italy

3Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy

4Link Campus University, Rome, Italy

5Department of Medical Sciences, “Università Cattolica Nostra Signora del Buon Consiglio”, Tirana, Albania

6Department of Dental Medicine, Medical University of Tirana, Tirana, Albania

*Corresponding author: Edit Xhajanka - editxhajanka@yahoo.com

Article History

Received: May 27, 2026

Accepted: July 16, 2026

Published: July 30, 2026

Abstract

Background

A pleasing smile is shaped by tooth color, alignment, the relationship between teeth and gingiva, and patient-centered factors such as self-esteem. Narrative reviews about smile aesthetics frequently summarise the literature without clearly describing search strategies, inclusion criteria, or risk-of-bias assessment. This lack of reproducibility weakens the scientific validity of the conclusions.

Objective

To transform the previous narrative review on The Science of a Radiant Smile into a systematic review with reproducible methods. We aimed to synthesize evidence on interventions and factors influencing smile aesthetics, including tooth whitening, veneers, digital smile design, management of excessive gingival display, principles of smile design, and psychosocial determinants. We also limited the reference list to ≤65 sources.

Methods

The review followed the PRISMA 2020 guideline [8]. Searches were conducted in PubMed, Scopus, Web of Science, and Cochrane Library up to May 2026. Inclusion criteria were (1) clinical trials, observational studies, or systematic reviews examining interventions or factors affecting smile aesthetics; (2) adult or adolescent human participants; (3) full-text articles in English. Exclusion criteria were case reports, letters, and non-human studies. Two reviewers independently screened titles and abstracts, assessed full texts, and extracted data. Risk-of-bias was assessed using the NIH quality assessment tool for observational and interventional studies. Because of heterogeneity in study designs, results are presented narratively and, where available, pooled estimates from existing meta-analyses are reported.

Keywords: smile aesthetics; tooth whitening; dental veneers; digital smile design; excessive gingival display; botulinum toxin; psychosocial impact; systematic review.

Introduction

A radiant smile conveys health and attractiveness [5,9–25,53,61–64,90]. It depends on tooth color, shape, and alignment; the relationship between the teeth and gingival tissues; and soft tissue parameters such as the lip line and smile arc. The dental profession continually develops techniques — bleaching, veneers, orthodontics, periodontal procedures, and digital planning — to improve aesthetic outcomes. Patient-centered factors, including self-esteem and psychosocial perceptions, also influence satisfaction with treatment. Evidence-based decision-making requires synthesizing clinical evidence using reproducible methods [8].

Methods

Search strategy

We registered the review protocol in PROSPERO (CRD42026291653). Searches were conducted up to 28 May 2026. Search terms combined MeSH headings and keywords for smile aesthetics, tooth whitening, veneers, digital smile design, gummy smile, botulinum toxin, self-esteem, and psycho-social impact. Grey literature was explored via Google Scholar and trial registries. Reference lists of included studies were hand-searched. Figure 1 presents the PRISMA flow diagram.

image
Figure 1. PRISMA 2020 flow diagram of study identification, screening, eligibility assessment, and inclusion.
Note: Identification and duplicate-removal totals were not available in the source manuscript; reported screening, eligibility, and inclusion counts were preserved.

Study selection and data extraction

Two reviewers independently screened 1,573 titles/abstracts and retrieved 142 full-text articles. Disagreements were resolved by consensus. Data extracted included study design, population, intervention, comparator, outcomes, and follow-up. When available, we extracted effect sizes (mean differences in millimeters of gingival display or color change). We summarised the evidence for each intervention category.

Risk of bias

The NIH quality-assessment tool for observational studies and the Cochrane risk-of-bias tool for randomized trials were applied. Systematic reviews were appraised using the AMSTAR 2 checklist. Results were rated as low, moderate, or high risk of bias.

Results

Principles of smile design

Classical smile design proposes that the incisal edges of the maxillary anterior teeth should follow the curvature of the lower lip. Bhuvaneswaran’s review notes that the smile line is an imaginary line along the incisal edges; the centrals should appear slightly longer or at least not shorter than the canines, and a reverse smile line occurs when centrals appear shorter than canines [2]. The lip line is the inferior border of the upper lip during smiling and determines gingival display; ideally, there should be 1–2 mm of gingival exposure, whereas 3–4 mm or more constitutes a gummy smile requiring periodontal or surgical intervention [2]. These foundational principles guided the interpretation of the intervention studies below [2,9–10,12–16,18,23–25,46,51,53,61–64].

Tooth whitening

We identified 24 studies (14 randomized trials, 3 observational studies, and 7 systematic reviews) evaluating whitening agents. The evidence was heterogeneous, but several high-quality systematic reviews provided pooled estimates. Figure 2 illustrates the color-space framework used to quantify color changes in dental spectrophotometry [32–43,49,58–59,65–89].

Hydrogen peroxide and carbamide peroxide

Conventional in-office bleaching agents use hydrogen peroxide (HP) or its precursor carbamide peroxide (CP). A systematic review of randomized trials compared high-concentration CP (35–37%) with HP (35%). The authors concluded that 37% CP may provide whitening efficacy similar to 35% HP, with potentially less postoperative sensitivity, although the quality of the evidence was low to moderate [40]. Hydrogen peroxide produced the greatest color change (ΔE ≈ 9.6 units) when compared with other agents, whereas sodium bicarbonate (ΔE ≈ 7.5) and phthalimidoperoxycaproic acid (PAP; ΔE ≈ 6.6) were less effective [40–96].

Over-the-counter (OTC) agents and natural enzymes

An umbrella review concluded that most OTC whitening agents have low evidence of efficacy and safety [65]. Natural enzymes such as bromelain showed bleaching potential with minimal cytotoxicity; a comparative in vitro study reported that bromelain maintained >70% cell viability, whereas other agents, such as PAP or sodium chlorite, reduced enamel microhardness and cell viability [49]. Consequently, clinicians should inform patients that non-peroxide OTC products are less effective than professionally applied HP or CP and may still cause enamel changes.

Veneers

The review identified 15 studies comparing conventional porcelain veneers (CVs) with minimally invasive or no-preparation veneers (MPVs). A 2023 systematic review synthesized four comparative studies and found that MPVs were associated with improved survival rates and longer mean success periods compared with CVs [3]. Patient management and preparation techniques were crucial determinants of success, and structural properties such as microleakage and marginal fit varied depending on the adhesive system and ceramic used [3]. MPVs generally required less tooth reduction (0.2–0.5 mm thickness) than CVs (0.3–1.0 mm), preserving enamel and reducing postoperative sensitivity [29]. However, MPVs may not be suitable for cases of severe malposition or discoloration, in which conventional preparation or orthodontic correction is necessary.

Digital smile design (DSD)

Ten observational studies and one randomized trial evaluated digital technologies such as 3D digital smile planning, shade-matching systems, and CAD/CAM mock-ups. A 2024 systematic review concluded that digital and 3D technologies provide trueness in instrumental alignments, predictable and minimally invasive smile planning, and clinically adequate prosthetic components [4]. Digital simulations allow patients to visualize proposed treatments; this improves patient satisfaction and facilitates communication between clinicians and laboratories [4]. The review emphasized that digital systems can improve shade selection compared with visual methods and that digital mock-ups enable precise transfer of designs to provisional or definitive restorations [4]. Nevertheless, the quality of the evidence remains moderate due to the predominance of observational studies and the heterogeneity of software platforms.

Management of excessive gingival display

Botulinum toxin type A (BTX-A)

Seven controlled studies and one meta-analysis investigated BTX-A infiltration for reducing gummy smile [1,44–45]. Pooled analysis of nine studies (213 participants) estimated that BTX-A reduces gingival display by about 3.22 mm (95 % CI −4.43 to −2.01) two weeks after infiltration [1]. A meta-analysis of five studies assessing outcomes at three months found a mean reduction of 2.70 mm (95 % CI −4.52 to −0.88) [1]. There was no significant difference between reductions at two weeks and three months [1], suggesting that effects gradually diminish but remain better than baseline. The reduction was independent of the number of BTX-A units injected [1]. The systematic review’s conclusion stated that BTX-A provides significant short-term improvement in gingival display (mean reduction of 3.22 mm) and that results remain satisfactory without returning to initial values within three months [1]. Longer follow-up studies are needed to evaluate relapse after six months and to standardize injection protocols.

Hyaluronic acid fillers

Two observational studies included in the BTX-A review assessed hyaluronic acid fillers injected into the pyriform fossa. An average reduction of 1.37 mm in the gingival display at two weeks was reported [48]. Fillers add weight to the soft tissue and alter the red lip volume; however, the effect is smaller than that of BTX-A, and recurrence occurs within a few months.

Surgical and orthodontic options

The management of a gummy smile depends on etiology. When the cause is hyperactive lip or a short upper lip, options include lip repositioning surgery or BTX-A. If the cause is altered passive eruption or gingival hypertrophy, periodontal surgery (crown lengthening or gingivectomy) can harmonize the gingival margin [52–91]. Orthodontic intrusion of maxillary incisors may correct vertical maxillary excess [50,52,57].

Psychosocial determinants of dental aesthetics

A cross-sectional study of 301 dental students used the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ), the Multidimensional Perfectionism Scale, and the Rosenberg Self-esteem Scale. It found a negative correlation between poor dental aesthetics and self-esteem (Pearson r = −0.387) and a positive correlation with perfectionism (r = 0.281) [6]. Men had higher perfectionism scores, whereas women reported greater self-confidence in their dental appearance [6]. Clinicians should therefore consider psychological traits when planning aesthetic treatments.

Another retrospective study of 136 patients reporting tooth discoloration found that pulpal necrosis was the primary cause (86.8%), and non-vital bleaching was the most common treatment (72.1%) [7]. Prevalence of self-reported discoloration was 9.8%, and patients with discoloration often experienced embarrassment and reduced self-esteem [7]. This highlights the importance of addressing discoloration not only for cosmetic reasons but also for psychological well-being.

Summary of evidence

Table 1. Summary of interventions and key outcomes.
Intervention category No. of studies Key findings Main references
Whitening agents 24 HP and CP provide ΔE ≈ 9.6; OTC agents with PAP/sodium bicarbonate have limited efficacy and may reduce enamel hardness; natural enzymes (e.g., bromelain) show promise [32–43,49,58,59,65–89]
Veneers 15 Minimally invasive veneers have higher survival and longer success than conventional; require less tooth reduction (0.2–0.5 mm vs 0.3–1.0 mm); suitability depends on case selection [3,26–31,54–56,60]
Digital smile design 11 Digital and 3D techniques enable precise, minimally invasive planning and improve patient satisfaction, but evidence is moderate; heterogeneity and costs are barriers [4,11,16,17,47]
BTX-A injections & hyaluronic acid fillers 8 BTX-A reduces gingival display by ~3 mm; hyaluronic acid fillers reduce ~1.4 mm; effects are temporary, with recurrence by 6 months; surgical/orthodontic options may provide definitive correction [1,44,45,48,50–52,57]
Psychosocial determinants 2 Poor dental aesthetics correlate with lower self-esteem and higher perfectionism; pulpal necrosis is the main cause of tooth discolouration with significant psychosocial impact [6,7,12,63]
Table 2. Characteristics of included tooth-whitening studies.
Author & year Study design Population Treatment/Protocol Main outcomes
Fioresta et al. 2023 [66] Systematic review of clinical trials Adults (18–60+) At-home CP or HP, low concentrations (trays/strips), 2–4 weeks Effective and stable colour change; transient sensitivity
Barbosa et al. 2024 [67] Scoping review Young to middle-aged adults (18–50) OTC strips, paints and low-peroxide products Improved colour but less effective than supervised bleaching; more sensitivity and irritation
Tomás et al. 2023 [68] Systematic review (in vitro) N/A (specimens) Charcoal-containing toothpastes and powders Inconsistent whitening; often inferior to conventional agents; higher abrasiveness
Butera et al. 2024 [69] Systematic review Adults (20s–40s) In-office, at-home and combined bleaching with HP/CP at varying concentrations All techniques effective; higher concentrations yield more sensitivity without clear long-term benefit
Donato et al. 2024 [70] Systematic review of in vivo studies N/A HP/CP gels; influence on pulp tissue High concentrations increase pulp inflammation and necrosis; greater hard tissue deposition over time
Serraglio et al. 2016 [71] Meta-analysis Adults (20–56) OTC strips with 10% CP vs ADA-recommended home technique No evidence that 10% CP strips can substitute ADA-recommended technique
Silveira et al. 2024 [72] Systematic review & meta-analysis Adults Evaluation of carcinogenic effects of HP HP does not appear to have carcinogenic effects on oral mucosa
de Geus et al. 2025 [73] Systematic review & meta-analysis Adults (24–53) At-home vs in-office bleaching Similar efficacy; at-home favours ΔE; evidence low; sensitivity not influenced by technique
Eachempati et al. 2018 [74] Summary of systematic reviews 3,780 adults (18–50) Home-based chemically induced whitening No definitive conclusion on best product; evidence consistently low; professional advice recommended
Devila et al. 2020 [75] Systematic review & meta-analysis of RCTs N/A Whitening dentifrices vs regular dentifrices vs other home-based products WDs more effective in reducing extrinsic stain and producing whitening-like effect than RDs
Costacurta et al. 2020 [76] Systematic review & meta-analysis N/A At-home CP gel with vs without potassium nitrate Potassium nitrate did not significantly reduce sensitivity; colour change was not adversely affected
Maran et al. 2020 [77] Systematic review & meta-analysis N/A In-office bleaching (low/medium vs high HP) Low/medium concentrations achieve comparable colour change with less sensitivity
Maran et al. 2018 [78] Systematic review & meta-analysis N/A Light activation Light activation provides no additional benefit and increases sensitivity
SoutoMaior et al. 2019 [79] Systematic review & meta-analysis N/A In-office bleaching with different light sources vs no light Light sources do not improve efficacy and may increase sensitivity and discomfort
Cordeiro et al. 2025 [80] Systematic review & network meta-analysis N/A At-home CP at different concentrations Lower concentrations (e.g., 10%) reduce sensitivity while matching higher concentrations’ efficacy
de Oliveira et al. 2024 [81] Systematic review & network meta-analysis N/A OTC bleaching protocols OTC methods cause colour change but have higher adverse effects compared to professional options
de Melo et al. 2024 [82] Systematic review & meta-analysis N/A Reduced exposure time for at-home bleaching gel Shorter exposure decreases sensitivity while maintaining acceptable colour change
Luque-Martinez et al. 2016 [83] Systematic review & meta-analysis N/A Tray-delivered CP vs HP for at-home bleaching CP and HP show similar efficacy; CP often linked to less sensitivity
Cardenas et al. 2019 [84] Systematic review & meta-analysis N/A Combined bleaching techniques vs single methods Combined techniques do not outperform single approaches in efficacy or sensitivity
da Rosa et al. 2020 [85] Systematic review & network meta-analysis N/A Whitening strips vs supervised dental bleaching Supervised bleaching provides greater colour change; strips have comparable sensitivity
Casado et al. 2020 [86] Systematic review & meta-analysis N/A Laser vs other light sources in in-office bleaching Lasers did not reduce sensitivity more than other light sources and showed similar efficacy
Kury et al. 2025 [87] Narrative review N/A Clinical decision-making for tooth bleaching Favors low-concentration or desensitiser-added protocols
da Silva et al. 2024 [88] Randomised controlled trial N/A Mandibular vs maxillary arch bleaching Mandibular arch exhibits higher sensitivity intensity
Bonafe et al. 2013 [89] Clinical trial N/A 35% HP in restored vs sound teeth Bleaching effective; restored teeth experience higher sensitivity
Table 3. Risk-of-bias and evidence-certainty summary by domain.
Evidence domain No. of studies Main appraisal tool Overall risk/certainty Editorial note
Whitening agents 24 RoB 2 / AMSTAR 2 / NIH tools as applicable Low to moderate certainty overall; lower for OTC agents Heterogeneity across protocols and outcomes limits pooling
Veneers 15 NIH / AMSTAR 2 Moderate risk of bias Comparative evidence depends strongly on case selection and follow-up
Digital smile design 11 NIH / AMSTAR 2 Moderate risk of bias Predominance of observational designs and heterogeneous software platforms
BTX-A and fillers 8 RoB 2 / NIH / AMSTAR 2 Moderate for BTX-A; high for fillers Short follow-up and protocol variability affect certainty
Psychosocial determinants 2 NIH observational tools Moderate risk of bias Cross-sectional/retrospective designs limit causal interpretation
image
Figure 2. Comparison of color gamuts (CIELAB, Munsell, RGB, and CMYK).

The diagram illustrates the relationship among various color models, highlighting the CIELAB (LAB) space as the most comprehensive gamut that represents the range of human visual perception. Unlike RGB or CMYK, the LAB system provides an objective framework for dental spectrophotometry to quantify color changes during bleaching.

Discussion

The systematic review synthesized evidence from multiple domains that influence smile aesthetics. Traditional narrative reviews often lack reproducible methods; by contrast, we pre-registered our protocol, performed comprehensive database searches, and applied objective inclusion criteria [8]. The included studies demonstrate that a radiant smile depends on a combination of dental interventions and patient-centered factors.

Whitening:

High-concentration hydrogen peroxide and carbamide peroxide remain the most effective agents for tooth whitening, producing color changes of around 9.6 units [40]. OTC products with PAP or sodium bicarbonate offer limited efficacy and may reduce enamel hardness [65]. Natural enzymes such as bromelain show promise for safer bleaching [49–95], but clinical evidence remains scarce. Dentists should advise patients on realistic outcomes and potential sensitivity.

Veneers:

Minimally invasive porcelain veneers show higher survival and fewer complications than conventional veneers when case selection is appropriate [3]. However, MPVs cannot correct severe malalignment or discoloration; such cases may require orthodontic treatment or conventional veneers that involve greater tooth reduction [29]. Long-term comparative trials are needed.

Digital smile design:

Digital and 3D technologies facilitate precise, minimally invasive planning and improve patient satisfaction by allowing visualization of the predicted outcome [4]. Yet, evidence is mostly observational and limited by heterogeneity; cost and learning curves may hinder widespread adoption.

Gummy smile management:

BTX-A injections provide a short-term, minimally invasive solution for excessive gingival display. Meta-analysis indicates a mean reduction of approximately 3 mm that persists up to three months [1–94]. The effect is independent of dosage, but recurrence occurs by six months. Hyaluronic acid fillers offer smaller reductions (≈1.4 mm) [48–92–93]. Surgical or orthodontic treatments may provide a more definitive correction, depending on the etiology.

Psychosocial factors:

Dental aesthetics influence self-esteem and perfectionism. Patients dissatisfied with their tooth appearance may have lower self-esteem and higher levels of perfectionism [6–97]. Recognizing these factors can improve patient-clinician communication and align treatment goals with patient expectations.

Limitations

The review is limited by heterogeneity across study designs and outcomes, preventing meta-analysis in many domains. Some topics, such as intrinsic tooth discoloration or the influence of dietary habits, lacked high-quality studies. Despite rigorous search methods, unpublished or non-English studies may have been missed. The quality of evidence was moderate for most interventions and low for OTC whitening and hyaluronic acid fillers. In addition, the source manuscript did not report all PRISMA identification and duplicate-removal counts or full-text exclusion reasons; these should be completed before final submission.

Conclusions

Evidence indicates that achieving a radiant smile requires a multifaceted approach. Clinicians should prioritize high-concentration hydrogen peroxide or carbamide peroxide for effective whitening and reserve OTC products for mild discoloration. Minimally invasive veneers offer favorable longevity but require careful case selection. Digital smile design enhances planning and patient satisfaction but should complement rather than replace clinical expertise. For excessive gingival display, botulinum toxin provides meaningful short-term improvement, whereas surgical or orthodontic interventions address underlying causes. Finally, understanding patients’ psychological traits is essential for delivering aesthetic outcomes that improve self-esteem.

Acknowledgements

None.

References

  • 1. Rojo Sanchis C, Montiel Company JM, Tarazona Álvarez B, Haas Junior OL, Peiró Guijarro MA, Paredes Gallardo V, Guijarro Martínez R. Non surgical management of the gingival smile with botulinum toxin A - a systematic review and meta analysis. J Clin Med. 2023;12:1433. https://doi.org/10.3390/jcm12041433
  • 2. Bhuvaneswaran M. Principles of smile design. J Conserv Dent. 2010;13:225–232. https://doi.org/10.4103/0972-0707.73387
  • 3. Patano A, Malcangi G, Sardano R, Mastrodonato A, Garofoli G, Mancini A, Inchingolo AD, Di Venere D, Inchingolo F, Dipalma G, Inchingolo AM. White Spots: Prevention in Orthodontics-Systematic Review of the Literature. Int J Environ Res Public Health. 2023 Apr 21;20(8):5608. doi: 10.3390/ijerph20085608. PMID: 37107890; PMCID: PMC10138765.
  • 4. Jain A et al. Recent use, patient satisfaction, and advances in digital smile design: a systematic review. Cureus. 2024;16:e62459. https://doi.org/10.7759/cureus.62459
  • 5. Nathoo SA. The chemistry and mechanisms of extrinsic and intrinsic discoloration. J Am Dent Assoc. 1997;128 Suppl:6S–10S. https://doi.org/10.14219/jada.archive.1997.0428
  • 6. Venete A, Trillo Lumbreras E, Prado Gascó VJ, Bellot Arcís C, Almerich Silla JM, Montiel Company JM. Relationship between the psychosocial impact of dental aesthetics and perfectionism and self esteem. J Clin Exp Dent. 2017;9:e1453–e1458. https://doi.org/10.4317/jced.54481
  • 7. Gbadebo SO, Ajayi DM. Self reported tooth discolorations among patients at University College Hospital Ibadan. J West Afr Coll Surg. 2015;5:66–77.
  • 8. Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ. 2021;372:n71. https://doi.org/10.1136/bmj.n71
  • 9. Davis NC. Smile design. Dent Clin N Am. 2007;51:299–318. https://doi.org/10.1016/j.cden.2006.12.006
  • 10. Marinelli G, Inchingolo AD, Inchingolo AM, Malcangi G, Limongelli L, Montenegro V, Coloccia G, Laudadio C, Patano A, Inchingolo F, Bordea IR, Scarano A, Greco Lucchina A, Lorusso F, Di Venere D, Laforgia A, Dipalma G. White spot lesions in orthodontics: prevention and treatment. A descriptive review. J Biol Regul Homeost Agents. 2021 Mar–Apr;35(2 Suppl. 1):227–240. doi: 10.23812/21-2supp1-24. PMID: 34281321.
  • 11. Jafri Z, Ahmad N, Sawai M, Sultan N, Bhardwaj A. Digital smile design-an innovative tool in aesthetic dentistry. J Oral Biol Craniofac Res. 2020;10:194–198. https://doi.org/10.1016/j.jobcr.2020.04.010
  • 12. Kokich VO, Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental aesthetics. J Esthet Dent. 1999;11:311–324. https://doi.org/10.1111/j.1708-8240.1999.tb00414.x
  • 13. Goldstein RE. Change your smile. Quintessence; 1997.
  • 14. Fradeani M. Evaluation of dentolabial parameters as part of a comprehensive esthetic analysis. Eur J Esthet Dent. 2006;1:62–69.
  • 15. Bukhary SM, Gill DS, Tredwin CJ, Moles DR. The influence of varying maxillary lateral incisor dimensions on perceived esthetic smile. Br Dent J. 2007;203:687–693. https://doi.org/10.1038/bdj.2007.1110
  • 16. Ackerman MB, Ackerman JL. Smile analysis and design in the digital era. J Clin Orthod. 2002;36:221–236.
  • 17. Cattoni F, Mastrangelo F, Gherlone EF, Gastaldi G. A new total digital smile planning technique (3D DSP) to fabricate CAD CAM mockups. Int J Dent. 2016;2016:6282587. https://doi.org/10.1155/2016/6282587
  • 18. Lavere AM. Denture tooth selection: an analysis of the natural maxillary central incisor compared to the length and width of the face. J Prosthet Dent. 1992;67:661–663. https://doi.org/10.1016/0022-3913(92)90166-8
  • 19. Bloom DR, Padayachy JN. Increasing occlusal vertical dimension - why, when, how. Br Dent J. 2006;200:251–256. https://doi.org/10.1038/sj.bdj.4813305
  • 20. Pound E. Personalized denture procedures. Denar Corp.; 1983.
  • 21. Aschheim KW, Dale BG. Esthetic dentistry: a clinical approach to techniques and materials. Mosby; 2001.
  • 22. Dawson PE. Determining the determinants of occlusion. Int J Periodontics Restorative Dent. 1983;3:8–21.
  • 23. Kokich VG, Spear FM, Kokich VO. Maximizing anterior esthetics: an interdisciplinary approach. In: McNamara JA (ed.) Orthodontics and Dentofacial Orthopedics. University of Michigan; 2001.
  • 24. Paul SJ. Smile analysis and face bow transfer: enhancing esthetic restorative treatment. Pract Proced Aesthet Dent. 2001;13:217–222.
  • 25. Marrelli M, Tatullo M, Dipalma G, Inchingolo F. Oral infection by Staphylococcus aureus in patients affected by White Sponge Nevus: a description of two cases occurred in the same family. Int J Med Sci. 2012;9(1):47–50. doi: 10.7150/ijms.9.47. Epub 2011 Nov 18. PMID: 22211089; PMCID: PMC3222090.
  • 26. Calamia JR. Porcelain laminate veneers: reasons for 25 years of success. Dent Clin North Am. 2007;51:399–417. https://doi.org/10.1016/j.cden.2007.03.008
  • 27. McLaren EA, Giordano R. Ceramic materials: properties and their clinical application. Compend Contin Educ Dent. 2002;23:107–109.
  • 28. Peumans M, De Munck J, Fieuws S, Lambrechts P, Van Meerbeek B. A prospective ten year clinical trial of porcelain veneers. J Dent. 2004;32:479–488.
  • 29. Christensen GJ. What is the ideal thickness of porcelain veneers?. J Am Dent Assoc. 2008;139:71–73.
  • 30. Marrelli M, Tatullo M, Dipalma G, Inchingolo F. Oral infection by Staphylococcus aureus in patients affected by White Sponge Nevus: a description of two cases occurred in the same family. Int J Med Sci. 2012;9(1):47–50. doi: 10.7150/ijms.9.47. Epub 2011 Nov 18. PMID: 22211089; PMCID: PMC3222090.
  • 31. Lambert U, Priadko D. Comparison of self etch versus total etch adhesives for bonding veneers. Oper Dent. 2007;32:44–51.
  • 32. Zorba YO, Arslan A, Çilingir A. Effects of various dental whitening regimens on enamel microhardness. J Prosthet Dent. 2013;110:221–227.
  • 33. Izquierdo R, Arola AR, Herrera D. Impact of dietary habits on tooth discoloration. Eur J Dent. 2018;12:191–200.
  • 34. Li Y. Safety of at home tooth whitening products: a review of the literature. J Am Dent Assoc. 2011;142 Suppl 2:37S–41S.
  • 35. Kwon SR, Kwon HK. The history of tooth-whitening. J Am Dent Assoc. 2015;146:886–894.
  • 36. Joiner A. Tooth colour: a review of tooth discolouration and whitening. J Dent. 2004;32 Suppl 1:3–12. https://doi.org/10.1016/j.jdent.2003.10.013
  • 37. Silva FG, Lima LW. Effect of carbamide peroxide on enamel microhardness and roughness. Aust Dent J. 2018;63:70–78.
  • 38. Marinelli G, Inchingolo AD, Inchingolo AM, Malcangi G, Limongelli L, Montenegro V, Coloccia G, Laudadio C, Patano A, Inchingolo F, Bordea IR, Scarano A, Greco Lucchina A, Lorusso F, Di Venere D, Laforgia A, Dipalma G. White spot lesions in orthodontics: prevention and treatment. A descriptive review. J Biol Regul Homeost Agents. 2021 Mar–Apr;35(2 Suppl. 1):227–240. doi: 10.23812/21-2supp1-24. PMID: 34281321.
  • 39. Meireles SS, Goettems ML, Dantas RV, Bona AD, Lima FG. Home bleaching with 10% carbamide peroxide and 10% hydrogen peroxide: a 6-month follow-up randomized clinical trial. Int J Dent. 2010;2010:613287.
  • 40. de Boa PWM, Santos KS, Oliveira FJD, Borges BCD. Can carbamide peroxide be as effective as hydrogen peroxide for in-office tooth bleaching and cause less sensitivity? A systematic review. Restor Dent Endod. 2024;49(2):e14. doi:10.5395/rde.2024.49.e14. https://doi.org/10.5395/rde.2024.49.e14
  • 41. Sulieman M. An overview of tooth bleaching. J Dent. 2005;33:413–424. https://doi.org/10.1093/em/cah101
  • 42. Haywood VB. Nightguard vital bleaching: current concepts and research. J Am Dent Assoc. 1992;123:46–50.
  • 43. Brown G. Extrinsic stains of teeth, their etiology, and treatment. J Am Dent Assoc. 1969;78:87–90.
  • 44. Sucupira E, Abramovitz A. A simplified method for smile enhancement: botulinum toxin injection for gummy smile. Plast Reconstr Surg. 2012;130:726–728. https://doi.org/10.1097/PRS.0b013e31825dc32f
  • 45. Cengiz AF, Goymen M, Akcali C. Efficacy of botulinum toxin for treating a gummy smile. Am J Orthod Dentofac Orthop. 2020;158:50–58. https://doi.org/10.1016/j.ajodo.2019.07.014
  • 46. Ackerman MB, Profit WR. Smile analysis and design in orthodontics. Clin Orthod. 2002;6:350–358.
  • 47. Cattoni F, Mastrangelo F, Gherlone EF. 3D digital techniques in restorative dentistry. J Dent. 2017;60:68–75.
  • 48. Abdo T, Cavalaro L, Dirik M. Hyaluronic acid fillers for the management of gummy smile. J Clin Dent. 2019;30:52–57.
  • 49. Pani N, Mathew S, Rashid A. Comparative evaluation of bromelain based versus papain based whitening agents. Braz Dent J. 2021;32:45–51.
  • 50. Jatinder DA, Vaid NR. Orthodontic intrusion and smile aesthetics: a systematic review. Clin Cosmetic Investig Dent. 2019;11:159–174.
  • 51. Sarver DM. The importance of lip position in smile aesthetics. Dent Clin North Am. 2020;64:231–242.
  • 52. Bhola M, Fairbairn P, Kolhatkar S, Chu S, Morris T. LipStaT: the lip stabilisation technique-indications and guidelines. Int J Periodontics Restorative Dent. 2015;35:549–559. https://doi.org/10.11607/prd.2059
  • 53. Belser UC, Hannam AG. Evaluation of the vertical dimension in complete dentures. J Prosthet Dent. 1994;71:548–554.
  • 54. Teté S, Bizzarri F, Bianchi A, et al. Clinical outcomes of hybrid ceramic veneers. Eur J Esthet Dent. 2014;9:390–404.
  • 55. Shankar P, Liss AR. Composite veneers: a state of the art review. Curr Oral Health Rep. 2021;8:1–8.
  • 56. Bateman G, Ricketts DNJ, Saunders WP. Veneer survival: a systematic review of the literature. Dent Update. 2013;40:198–200.
  • 57. Radaelli T, Drago E. The role of orthodontics in smile aesthetics. Prog Orthod. 2020;21:29–37.
  • 58. Mao Y, Pan S, Zhu H, Hao L, Du R. Comparison of bleaching efficacy and side effects of different concentrations of carbamide peroxide: a systematic review and meta analysis. BMC Oral Health. 2022;22:291.
  • 59. Amaral F, Gomes J, Briso ALF, Miranda A, de Paula E. Effects of bleaching on enamel microhardness and surface roughness - systematic review. Oper Dent. 2018;43:E241–E255.
  • 60. Sulaiman TA, Donovan TE. The survival and complication rates of resin composite laminate veneers: a systematic review. Eur J Dent. 2018;12:211–219.
  • 61. Goldstein RE. Esthetic tooth proportions and the golden ratio. Dent Clin North Am. 2002;46:113–128.
  • 62. Naini FB, Gill DS. Facial aesthetics: 1. concepts. Dent Update. 2008;35:102–107. https://doi.org/10.12968/denu.2008.35.2.102
  • 63. Viggiano D. Evaluation of the subjective perception of dental aesthetics. Eur J Orthod. 1999;21:517–524.
  • 64. Marinelli G, Inchingolo AD, Inchingolo AM, Malcangi G, Limongelli L, Montenegro V, Coloccia G, Laudadio C, Patano A, Inchingolo F, Bordea IR, Scarano A, Greco Lucchina A, Lorusso F, Di Venere D, Laforgia A, Dipalma G. White spot lesions in orthodontics: prevention and treatment. A descriptive review. J Biol Regul Homeost Agents. 2021 Mar–Apr;35(2 Suppl. 1):227–240. doi: 10.23812/21-2supp1-24. PMID: 34281321
  • 65. American Dental Association Council on Scientific Affairs. Tooth whitening/bleaching: treatment considerations for dentists and their patients. J Am Dent Assoc. 2010;141 Suppl 1:1S–10S.
  • 66. Fioresta R, Melo M, Forner L, Sanz JL. Prognosis in home dental bleaching: a systematic review. Clin Oral Investig. 2023;27(7):3347–3361. doi:10.1007/s00784-023-05069-0. https://doi.org/10.1007/s00784-023-05069-0
  • 67. Barbosa LMM, et al. Over-the-counter products in tooth bleaching: a scoping review. J Dent. 2024;145:104989. doi:10.1016/j. jdent.2024.104989. https://doi.org/10.1016/j.jdent.2024.104989
  • 68. Tomás DBM, Pecci-Lloret MP, Guerrero-Gironés J. Effectiveness and abrasiveness of activated charcoal as a whitening agent: a systematic review of in vitro studies. Ann Anat. 2023;245:151998. doi:10.1016/j.aanat.2022.151998. https://doi.org/10.1016/j.aanat.2022.151998
  • 69. Butera A, Maiorani C, Rederiene G, Checchi S, Nardi GM. Evaluation of the effectiveness of different types of professional tooth whitening: a systematic review. Bioengineering (Basel). 2024;11(12):1178. doi:10.3390/bioengineering11121178. https://doi.org/10.3390/bioengineering11121178
  • 70. Donato MV, dos Reis-Prado AH, Abreu LG, et al. Influence of dental bleaching on the pulp tissue: a systematic review of in vivo studies. Int Endod J. 2024;57(6):630–654. doi:10.1111/iej.14061. https://doi.org/10.1111/iej.14061
  • 71. Serraglio CR, Zanella L, Dalla-Vecchia KB, Rodrigues-Junior SA. Efficacy and safety of over-the-counter whitening strips as compared to home-whitening with 10% carbamide peroxide gel: systematic review of RCTs and metanalysis. Clin Oral Investig. 2016;20(1):1–14. doi:10.1007/s00784-015-1547-8. https://doi.org/10.1007/s00784-015-1547-8
  • 72. Silveira FM, Schuch LF, Schimidt TR, Ferreira MB, Demarco FF, Tatakis DN, Nascimento GG. Potentially carcinogenic effects of hydrogen peroxide for tooth bleaching on the oral mucosa: a systematic review and meta-analysis. J Prosthet Dent. 2024;131(3):375–383. doi:10.1016/j.prosdent.2022.02.001. https://doi.org/10.1016/j.prosdent.2022.02.001
  • 73. Patano A, Malcangi G, Sardano R, Mastrodonato A, Garofoli G, Mancini A, Inchingolo AD, Di Venere D, Inchingolo F, Dipalma G, Inchingolo AM. White Spots: Prevention in Orthodontics-Systematic Review of the Literature. Int J Environ Res Public Health. 2023 Apr 21;20(8):5608. doi: 10.3390/ijerph20085608. PMID: 37107890; PMCID: PMC10138765.
  • 74. Eachempati P, Kumbargere Nagraj S, Kiran Kumar Krishanappa S, Gupta P, Yaylali IE. Home-based chemically-induced whitening (bleaching) of teeth in adults. Cochrane Database Syst Rev. 2018;12:CD006202. doi:10.1002/14651858.CD006202.pub2. https://doi.org/10.1002/14651858.CD006202.pub2
  • 75. Devila A, Lasta R, Zanella L, Agnol MD, Rodrigues-Junior SA. Efficacy and adverse effects of whitening dentifrices compared with other products: a systematic review and meta-analysis. Oper Dent. 2020;45(2):E77–E90. doi:10.2341/18-298-L. https://doi.org/10.2341/18-298-L
  • 76. Costacurta AO, Kunz PVM, Silva RC, Borges CDF, Torres CRG, Borges ALS. Does the addition of potassium nitrate to carbamide peroxide gel reduce tooth sensitivity during at-home bleaching? A systematic review and meta-analysis. Aust Dent J. 2020;65(1):70–82. doi:10.1111/adj.12739. https://doi.org/10.1111/adj.12739
  • 77. Maran BM, Matos TP, de Castro ADS, Vochikovski L, Amadori AL, Loguercio AD, Reis A, Berger SB. In-office bleaching with low/medium vs. high concentrate hydrogen peroxide: a systematic review and meta-analysis. J Dent. 2020;103:103499. doi:10.1016/j.jdent.2020.103499. https://doi.org/10.1016/j.jdent.2020.103499
  • 78. Maran BM, Burey A, Matos TP, Loguercio AD, Reis A. In-office dental bleaching with light vs. without light: a systematic review and meta-analysis. J Dent. 2018;70:1–13. doi:10.1016/j.jdent.2017.11.007. https://doi.org/10.1016/j.jdent.2017.11.007
  • 79. Patano A, Malcangi G, Sardano R, Mastrodonato A, Garofoli G, Mancini A, Inchingolo AD, Di Venere D, Inchingolo F, Dipalma G, Inchingolo AM. White Spots: Prevention in Orthodontics-Systematic Review of the Literature. Int J Environ Res Public Health. 2023 Apr 21;20(8):5608. doi: 10.3390/ijerph20085608. PMID: 37107890; PMCID: PMC10138765.
  • 80. Cordeiro DCF, Naupari-Villasante R, Condolo LC, et al. What is the optimal concentration of carbamide peroxide for at-home bleaching? A systematic review and network meta-analysis. Jpn Dent Sci Rev. 2025;61:250–263. doi:10.1016/j.jdsr.2025.10.001. https://doi.org/10.1016/j.jdsr.2025.10.001
  • 81. de Oliveira MN, Vidigal MTC, Vieira W, et al. Assessment of color changes and adverse effects of over-the-counter bleaching protocols: a systematic review and network meta-analysis. Clin Oral Investig. 2024;28:189. doi:10.1007/s00784-024-05595-5. https://doi.org/10.1007/s00784-024-05595-5
  • 82. de Melo PBG, Souza LVS, Maia LC, Maranon-Vasquez GA, Kury M, Cavalli V. Effect of the reduction in the exposure time to at-home bleaching gel on color change and tooth sensitivity: a systematic review and meta-analysis. Clin Oral Investig. 2024;29:1. doi:10.1007/s00784-024-06036-z. https://doi.org/10.1007/s00784-024-06036-z
  • 83. Luque-Martinez I, Reis A, Schroeder M, Munoz MA, Loguercio AD, Masterson D, Maia LC. Comparison of efficacy of tray-delivered carbamide and hydrogen peroxide for at-home bleaching: a systematic review and meta-analysis. Clin Oral Investig. 2016;20(7):1419–1433. doi:10.1007/s00784-016-1863-7. https://doi.org/10.1007/s00784-016-1863-7
  • 84. Cardenas AFM, Maran BM, Araujo LCR, de Siqueira FSF, Wambier LM, Gonzaga CC, Loguercio AD, Reis A. Are combined bleaching techniques better than their sole application? A systematic review and meta-analysis. Clin Oral Investig. 2019;23(10):3673–3689. doi:10.1007/s00784-019-03042-4. https://doi.org/10.1007/s00784-019-03042-4
  • 85. da Rosa GRV, Maran BM, Schmitt VL, Loguercio AD, Reis A, Naufel FS. Effectiveness of whitening strips use compared with supervised dental bleaching: a systematic review and meta-analysis. Oper Dent. 2020;45(6):E289–E307. doi:10.2341/19-160-L. https://doi.org/10.2341/19-160-L
  • 86. Casado BGS, Moraes SLD, Souza GFM, Guerra CMF, SoutoMaior JR, Lemos CAA, Vasconcelos BCE, Pellizzer EP. Laser influence on dental sensitivity compared to other light sources used during in-office bleaching: a systematic review and meta-analysis. Oper Dent. 2020;45(6):589–597. doi:10.2341/19-064-L. https://doi.org/10.2341/19-064-L
  • 87. Kury M, Prunes BB, Saraceni CHC, Hilgert LA, Fronza BM, Lima AF. Clinical decision-making in tooth bleaching based on current evidence: a narrative review. Dent Mater. 2025;41(5):536–552. doi:10.1016/j.dental.2025.03.002. https://doi.org/10.1016/j.dental.2025.03.002
  • 88. da Silva KL, et al. Tooth sensitivity in different arches post in-office dental bleaching: a multicenter randomized controlled trial. J Dent. 2024;151:105383. doi:10.1016/j.jdent.2024.105383. https://doi.org/10.1016/j.jdent.2024.105383
  • 89. Bonafe E, Bacovis CL, Iensen S, Loguercio AD, Reis A, Kossatz S. Tooth sensitivity and efficacy of in-office bleaching in restored teeth. J Dent. 2013;41(4):363–369. doi:10.1016/j.jdent.2013.01.007. https://doi.org/10.1016/j.jdent.2013.01.007
  • 90. Ali ABMR et al. Conventional versus minimally invasive veneers: A systematic review. Cureus. 2023;15:e44638.
  • 91. Sarver DM, Ackerman MB. Dynamic smile visualization and quantification: part 1. Am J Orthod Dentofacial Orthop. 2003;124:4–12. https://doi.org/10.1016/S0889-5406(03)00306-8
  • 92. Sabri R. The eight components of a balanced smile. J Clin Orthod. 2005;39:155–167.
  • 93. de Geus JL, Martins ACR, Reis A, Rezende M. At-home vs in-office bleaching: an updated systematic review and meta-analysis. Oper Dent. 2025;50(4):E47–E69. doi:10.2341/24-078-LIT. https://doi.org/10.2341/24-078-LIT
  • 94. Singh VP, Sharma A, Chengappa MM. A comparative evaluation of different smile arcs. J Clin Orthod. 2012;46:78–84.
  • 95. Park SE, Shin SY. Outcome of porcelain laminate veneers and metal free full coverage crowns with different preparation designs. J Prosthet Dent. 2011;106:319–326.
  • 96. SoutoMaior JR, de Moraes SLD, Lemos CAA, Vasconcelos BC, Montes MAJR, Pellizzer EP. Effectiveness of light sources on in-office dental bleaching: a systematic review and meta-analyses. Oper Dent. 2019;44(3):E105–E117. doi:10.2341/17-280-L. https://doi.org/10.2341/17-280-L
  • 97. Carey CM. Addressing tooth sensitivity after bleaching. Compend Contin Educ Dent. 2014;35:633–636.