Available online 3 May 2024

Author links open overlay panel, , , , , ABSTRACTStatement of problem

The gingival zenith (GZ) influences the line angle position in the emergence profile and the axial inclination of the crown. Irregularities in GZ symmetry and contour have a negative impact on dental esthetics. GZ location is not consistently distal to the crown's long axis; instead, it tends to be more distal in anterior teeth. The GZ levelling of the lateral incisor is often described as either level with or slightly above the zenith line connecting the central incisor and canine teeth, but there are also reports of GZ being aligned apically to the zenith line. Controversial reports persist regarding GZ positioning, magnitude, and location, potentially leading to inadequate positioning and levelling of the GZ in esthetic restorative therapy.

Purpose

The purpose of this systematic review and meta-analysis was to assess the scientific evidence related to GZ level, position, and symmetry in maxillary incisors and canines.

Material and methods

This study adhered to the population, variable, outcome (PVO) criteria and the preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist. Cross-sectional studies involving healthy adults with complete dentition of the maxillary anterior sextant were subjected to prevalence analysis and quantitative measurement to assess the gingival zenith level and position. Data were extracted, and methodological quality was appraised using the Joanna Briggs Institute critical appraisal checklist for analytical cross-sectional studies. Certainty of evidence was evaluated through the grading of recommendations, assessment, development, and evaluation (GRADE) system.

Results

The GZs were distally positioned, coinciding with the tooth axis or mesially positioned in, respectively, 96%, 3%, and 1% on central incisors; 84%, 14%, and 1% on lateral incisors; and 43%, 44%, and 5% on canines. GZ distal positioning was greater in central incisors, followed by lateral incisors and canines. In lateral incisors, the GZ was levelled coronally in 82% of the population. Contralateral symmetry was observed for GZ levelling and positioning. The certainty of the evidence was very low for all comparisons.

Conclusions

The frequency and magnitude of the distal position of the GZ increased the more anterior the tooth. Axially, the GZ was frequently levelled coronally to the zenith line. The contralateral positioning and levelling of the GZ was symmetrical.

Section snippetsMATERIAL AND METHODS

The present study followed the guidelines outlined in the preferred reporting items for systematic review and meta-analysis (PRISMA) checklist37 and the Cochrane Handbook for Systematic Reviews of Interventions.38 The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under the registration number CRD42021229656. Two focused research questions were formulated using the population, variable, outcome (PVO) tool39: “In the maxillary dentition of

RESULTS

A summary flowchart outlining the selection process is presented in Figure 2. Initially, 9267 records were identified through the electronic search. After removing duplicates, 4574 records remained for abstract screening. Following the exclusion of 4331 studies, the full text of 243 studies was evaluated. After excluding 224 studies based on full-text analysis, 19 remained for data extraction. E-mails were sent to 14 authors to obtain additional information, but only 4 responded with further

DISCUSSION

From the current systematic review, 3 main conclusions were drawn: the more anterior the tooth, the greater prevalence and magnitude of the distal position of the GZ in relation to the long axis of the crown; the GZ of lateral incisors is more frequently levelled coronally to the zenith line; and the distal position of the GZ of the central, lateral incisor, and canine, along with the apicocoronal levelling of the GZ of lateral incisor teeth demonstrates contralateral symmetry. Therefore, the

CONCLUSIONS

Based on the findings of this systematic review and meta-analysis, the following conclusions were drawn:

1.

The position of the GZ toward the distal is not a universal finding.

2.

The frequency and magnitude of the distal position of the GZ increases the more anterior the tooth and coincides more frequently with the long axis in the canines.

3.

Axially, the GZ is frequently levelled coronally to the zenith line, and the positioning and levelling of the GZ are contralaterally symmetrical in the maxillary

Ethics Approval and Consent to Participate

Not Applicable.

CRediT authorship contribution statement

Carolina Miller Mattos de Santana and Ronaldo Barcellos de Santana: Conceptualization. Felipe V. Martins, Carolina Miller Mattos de Santana, Marcela Baraúna Magno, Lucianne Cople Maia, Edgard M. Fonseca and Ronaldo Barcellos de Santana: Study design. Felipe V. Martins, Carolina Miller Mattos de Santana: Data collection. Marcela Baraúna Magno, Lucianne Cople Maia and Ronaldo Barcellos de Santana: Data analysis. Felipe V. Martins and Ronaldo Barcellos de Santana: Manuscript writing. Carolina

Acknowledgments

This study was financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) – Brasil.The authors thank Nappe et al (2015), Bamusa et al (2018), Ganji et al (2018), and Patil et al (2020), who kindly provided additional data not given in the published texts.

REFERENCES (41)S.J. Chu et al.Gingival zenith positions and levels of the maxillary anterior dentition

J Esthet Restor Dent

(2009)

M. Zagar et al.A quantitative evaluation of the distal displacement of the gingival zenith in the maxillary anterior teeth

Coll Antropol

(2010)

X.P. Ke et al.A quantitative research on clinical parameters of gingival contour for anterior teeth esthetic analysis and design

J Esthet Restor Dent

(2018)

D. AppukuttanAssessment of gingival zenith position and distance from vertical bisecting midline in the maxillary anterior dentition − An observational study

J Orofac Sci

(2018)

A. Kolte et al.Assessment of tooth and gingival display in maxillary anterior teeth and premolars relative to gingival and interdental smile lines

Int J Esthet Dent

(2020)

A.P. Kolte et al.Assessment of gingival zenith position and its level relative to age and gender in maxillary anterior teeth

Quintessence Int

(2018)

A.S. Patil et al.Pink esthetics: A study on significant gingival parameters

J Contemp Dent Pract

(2020)

S. Charruel et al.Gingival contour assessment: Clinical parameters useful for esthetic diagnosis and treatment

J Periodontol

(2008)

C.R. RufenachtFundamentals of Esthetics

(1990)

N.L. FeigenbaumAspects of aesthetic smile design

Pract Periodontics Aesthet Dent

(1991)

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