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ORIGINAL ARTICLE
Year : 2018  |  Volume : 10  |  Issue : 1  |  Page : 14-18

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


Department of Periodontics, SRM Dental College and Hospital, Chennai, Tamil Nadu, India

Date of Web Publication9-Jul-2018

Correspondence Address:
Dr. Devapriya Appukuttan
Department of Periodontics, SRM Dental College and Hospital, Chennai 600089, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jofs.jofs_32_17

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  Abstract 


Background: Esthetics in the maxillary anterior segment is determined by both the hard and soft tissues. Gingival contour plays a vital role in pink esthetics. The most common apical position of the marginal gingiva is referred to as gingival zenith (GZ). This study aimed to assess the position and distance of the GZ from the vertical bisecting midline (VBM) in the anterior maxillary dentition in a sample of South Indian population. Materials and Methods: A total of 105 participants were recruited based on specific inclusion and exclusion criteria. Following recruitment, alginate impressions were made, and dental cast were poured. A total of 630 anterior teeth were evaluated on the cast. The position of the GZ was marked, and a vertical line was drawn through the point. The VBM was drawn on the cast based on the crown width. Using magnification loupes (2.5×) and calibrated digital vernier caliper, the distance between the GZ and VBM was measured twice for each tooth, and the average reading was recorded. The position of GZ was recorded as mesial, distal, or coinciding with the VBM. Results: Majority of the right and left maxillary central incisors and lateral incisors were placed distal to the VBM measuring a mean distance of 0.7 ± 0.4 and 0.76 ± 0.36 mm, respectively, for centrals and 0.59 ± 0.3 and 0.62 ± 0.31 mm, respectively, for laterals. The GZ of both the right and left canines were mesial to the VBM at a mean distance of 0.59 ± 0.4 and 0.61 ± 0.3 mm, respectively. Conclusion: Familiarity with the position and distance of the GZ enables the dentist to plan an appropriate esthetic rehabilitation for the patients based on the population in question.

Keywords: Esthetics, gingival zenith, magnification loupes, vertical bisecting midline, vernier caliper


How to cite this article:
Appukuttan D, Cholan PK, Ashwini CR, Swapna S. Assessment of gingival zenith position and distance from vertical bisecting midline in the maxillary anterior dentition − An observational study . J Orofac Sci 2018;10:14-8

How to cite this URL:
Appukuttan D, Cholan PK, Ashwini CR, Swapna S. Assessment of gingival zenith position and distance from vertical bisecting midline in the maxillary anterior dentition − An observational study . J Orofac Sci [serial online] 2018 [cited 2018 Nov 20];10:14-8. Available from: http://www.jofs.in/text.asp?2018/10/1/14/236205




  Introduction Top


A warm smile is the universal language of kindness, and it attracts positivity and affection, in addition to covering all asymmetries in the face. In this context, it is the dentists, rather than the general healthcare physicians, who have an upper hand in creating and preserving one’s smile.[1] Esthetics is a part and parcel of an individual’s life, and certain standards and proportions along with social acceptance define esthetics. The face is the social identity of a person and is considered essential for physical attractiveness. An esthetic smile design is based on white and pink esthetics contributed by the face, lips, gingiva, and the teeth.[1],[2] In the current scenario, cosmetic or esthetic dentistry is being given prime importance because majority of the patients report discontent with the appearance of their teeth or gums. This is reflected in the increasing number of newer cosmetic therapies such as clear orthodontic aligners, teeth whitening, composite bonding, smile line correction, periodontal plastic surgeries, and veneers.

Healthy gingival architecture is characterized by a knife-edged gingival margin, which is tightly adherent to the tooth surface, as well as a cone-shaped or pointed interdental papilla in concert with the most apical point in the gingival margin, the gingival zenith (GZ).[3] Gingival and periodontal diseases, traumatic practices such as the improper use of dental floss and forceful tooth brushing, inappropriate restorations and prosthetic crowns, and multiple other factors disrupt the gingival architecture resulting in “black triangle” eventually leading to an unappealing smile.[3] The maxillary and mandibular midlines are also accentuated in facial esthetic evaluation contributing to a graceful smile. Any significant discrepancies between the facial and dental midline perturb the attractiveness of a smile.[4] Therefore, establishing these parameters prior to smile designing or esthetic rehabilitation in the maxillary anterior segment is a necessity in clinical practice, because the patients are extremely concerned with the treatment results.[1] Despite the continual efforts by researchers to establish universal guidelines for creating an esthetic smile, literature evidences are conflicting and varied.[5] Unequivocal attention should be given to soft tissue contours such as the gingival zenith position (GZP), because they play an essential role in contributing to an esthetic smile. Hence, any deviation or not taking into consideration these anatomic landmarks might result in an unpleasant smile and an unhappy patient.

Hence, with the above background in mind, we planned this analytical study to evaluate the GZP and its distance in relation to the vertical bisecting midline (VBM) of each maxillary anterior tooth.


  Materials and Methods Top


This cross-sectional study was conducted in the Department of Periodontics, SRM Dental College and Hospital, Chennai from August 2016 to November 2016. Ethical clearance for the study was received(SRMU/M&HS/SRMDC/2016/M.D.S.- PGstudent/005) from the institutional review board of SRM University, Chennai on 15th september 2016. The study sample included 105 systemically healthy participants of both genders, with ages ranging from 17 to 25 years (mean age 21 ± 3.4 years). Participants were excluded from participating if they had restored their maxillary anterior teeth, had interdental papillae loss, anterior crowding and spacing, a history of prior orthodontic correction, the presence of incisal attrition, periodontal disease, and gingival recession. The armamentarium included alginate impression material and metal impression stock trays, graduated metal scale, carbon marker, calibrated digital vernier caliper with LED display (measuring range: 0–150 mm or 0–6 inch; resolution: 0.01 mm or 0.0005 inch; repeatability: 0.01 mm or 0.0005 inch, SAE − Avenger Measuring Tools, China), and a pair of magnification loupes (2.5× magnification, STAC loupes, AMT Dental Pvt. Ltd., Canada) [Figure 1].
Figure 1: The vernier caliper and magnification loupe used in the study

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Once the participants were recruited, irreversible hydrocolloid impression material was used to record the upper and lower impressions and was poured with a dental stone. Subsequently, the cast was removed, and the highest point of the free gingival margin, GZ, was marked on all the upper anterior teeth. A line was drawn through the GZP using a carbon marker. The VBM of each clinical crown was determined by measuring the tooth width at two reference points namely the proximal incisal contact area position and the apical contact area position. The center points were marked by dividing the calculated mesiodistal width by half [Figure 2]. These center points were joined by a line extending from the incisal aspect to the gingival aspect of the clinical crown, defining the VBM. The distance of the GZP to the VBM was measured along the medial–lateral direction for all the central incisors, lateral incisors, and canines. The measurements were taken using a digital caliper with LED display (SAE − Avenger Measuring Tools, China). The measurements were taken three times, and the average was recorded. The measurements were gauged by a single examiner, who was calibrated at the outset of the study. The examiner was asked to take dimensions under magnifying loupes on the same five casts from different participants at two time points at an interval of one week. Kappa statistics was calculated for agreement. The value was 0.9, indicating very good agreement. Care was taken to eliminate any operator and methodology bias during the duration of the study.
Figure 2: The gingival zenith and vertical bisecting midline marked on the cast

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Statistical analysis

Raw data were entered into an Excel spreadsheet, and statistical analysis was performed using Statistical Package for the Social Sciences (SPSS Statistics for Windows, Version 17.0. Chicago: SPSS Inc.) version 17.0 software. The mean distance of the GZP from the VBM and standard deviation along with minimum and maximum values were calculated. The independent t-test was performed to analyse the statistical difference in the distance between the GZP and the VBM between the right and left sides of the maxillary anterior teeth. The position of the GZP for all the teeth was represented as the number and percentage of mesial, distal, or coinciding with the VBM cases.


  Results Top


A total of 630 maxillary anterior teeth were analyzed on the cast. [Table 1] shows the position of the GZP as mesial, distal, or coinciding with the VBM. The analysis using vernier caliper showed that 71.42% of the right central incisors displayed a distal GZP, 20.95% a mesial GZP, and 7.61% a GZP coinciding with the VBM. Moreover, 69.52% of the left central incisors displayed a distal placement of the GZP from the VBM, 26.66% a mesial GZP, and 3.8% a GZP coinciding with the VBM. Overall, it was noticed that the central incisors predominantly showed a distal placement of the GZP in relation to the VBM. Similarly, 75.23% of the right lateral incisors presented with a distal GZP from the VBM, 22.8% with a mesial GZP, and 1.9% a GZP coinciding with the VBM. For the left lateral incisors, 49.52% showed a distal GZP from the VBM, 46.66% a mesial GZP, and 3.8% a GZP coinciding with the VBM. Similar to the central incisors, the majority of the lateral incisors showed a distal displacement of the GZP from the VBM.
Table 1: The gingival zenith position in relation to the vertical bisected midline

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It was seen that 45.71% of GZP of the right canines was mesial to the VBM, 37.14% showed distally placed GZP from the VBM, and 17.14% demonstrated GZP that was concurrent with the VBM. Similarly, the GZP of the left canines were predominantly, that is, 51.42% placed mesial to VBM, 34.28% showed distally placed GZP, and 14.28% coinciding with the VBM. Taken as a whole, the canines showed a mesial displacement of the GZP from the VBM. Overall, the central incisors showed a distal displacement of the GZP from the VBM (70.5%), the lateral incisors had a distal displacement of the GZP (62.3%), and canines (48.6%) elicited a mesial shift of the GZP from the VBM.

[Table 2] shows the descriptive values of GZP distances from the VBM of the clinical crowns of the maxillary anterior dentition. The mean distances of the GZP to the VBM of the clinical crown of the right central incisors, right lateral incisors, and right canines were 0.70 ± 0.4, 0.58 ± 0.3, and 0.58 ± 0.4 mm, respectively. The mean distances of the GZP from the VBM of the clinical crown of the left central incisors, lateral incisors, and canines were 0.75 ± 0.3, 0.61 ± 0.31, and 0.61 ± 0.3 mm, respectively. The mean distances of the GZP to the VBM of the central incisors, lateral incisors, and canines were 0.73 ± 0.3, 0.60 ± 0.3, and 0.59 ± 0.3 mm, respectively.
Table 2: The distance (mm) of the gingival zenith position from the vertical bisected midline

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[Table 3] elaborates the test of significance for difference between the distances of the GZP from the VBM for the central incisor, lateral incisor, and canine between the right and left sides. For the central incisors, the P value was 0.28, which is not significant. The P values of the lateral incisors and canines were 0.44 and 0.66, respectively, which were also found to be not significant statistically.
Table 3: The comparison of distance between the GZP and VBM between the right and left sides of the maxillary anterior teeth

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  Discussion Top


The goal of this study was to establish a representative value for the position and mean distance of the GZP from the VBM of the maxillary anterior dentition in a sample of South Indian adult population. A beautiful restoration without a properly designed gingival tissue has a negative impact on a person’s smile.[3] Hence, gingival esthetics form an essential component of a beautiful smile design. There is no universal textbook guideline for clinicians to follow while determining the position and distance of the GZP, because it would depend on multiple factors including the ethnicity of the participants.

In this study, analysis revealed that the GZP of majority of the central incisors were distally placed in relation to the VBM at an average distance of 0.73 mm from the VBM. This was in concordance with the studies by Rufenacht,[6],[7] Goodlin,[8] Mattos and Santana,[9] Chu et al.,[3] and Žagar et al.,[10] despite the fact that those studies were conducted among participants belonging to different races. A similar observation was reported by Shah et al.[11] in Indian population. Hence, this study is in agreement with the observations put forth by other Indian authors. It was observed that most frequently the lateral incisors showed a distal displacement of the GZP at an average distance of 0.60 mm from the VBM. A similar trend was noticed by Chu et al.[3] and Mattos and Santana[9] On the contrary, studies published by Rufenacht[6],[7] and Goodlin[8] were in disagreement and concluded that the laterals commonly showed a GZP that was coinciding with the VBM. Rathod et al.[12] showed that the GZ was frequently placed distal to the VBM in all the maxillary teeth. Ahmad[13] noticed that the GZP coincided with the VBM more usually in the lateral incisors. The dimensions analyzed in this study revealed that the canines mostly were mesial to the VBM at a mean distance of 0.6 mm. This was in contrast to the studies by Mattos[9] and Rufenacht[6],[7] These authors demonstrated that frequently canines showed a distal shift of the GZP from the VBM. Žagar et al.[10] demonstrated that the canines had their GZP coinciding with the VBM. Therefore, literature evidence indicates that the canines show greater variability in their GZP.

The current study did not show any significant variation in the distance of the GZP from the VBM between the left and right maxillary central incisors, lateral incisors, and canines. This is in disagreement with the study by Humagain et al.,[14] wherein they observed significant difference in the distance between the right and left lateral incisors. Bishara et al.[15] hypothesized from their study that asymmetry do exists between the left and right sides, and minor discrepancy is acceptable, because no two objects are similar in nature for instance, even though mirror images may be identical, but they may not exhibit similar parameters. Bhatsange et al.[16] hypothesized that variations existed in the GZPs based on the four facial forms such as oval, square, square tapering, and tapering. Similarly, Gowd et al.[17] emphasized the variation in the GZP based on the degree of proclination of the maxillary anterior teeth during orthodontic treatment.

Summarizing, this study has attempted to establish certain important parameters that should be taken into consideration during planning and the rehabilitation of the anterior esthetic zone. These results may not coincide with the studies conducted by researchers in Caucasian population or other races due to inter-racial differences in tooth size, shape, and anatomy. In addition, small sample size is a possible limitation in this study. Measurements were taken with utmost care to eliminate errors and bias. However, due to the usage of simple magnifying loupes and digital vernier caliper, parallax errors might have occurred. The parameters thus established possibly are applicable to South Indian adult population.


  Conclusion Top


Our study highlights the importance of the GZP in designing macroesthetics and microesthetics as well. The GZ was positioned 0.73 mm distally from the VBM in the central incisor group. The lateral incisor showed a distal displacement of 0.60 mm of the GZP from the VBM. The canines had the GZP at a mean distance of 0.59 mm, mesial to the VBM in this study. These parameters become vital during the treatment planning of restorations in the maxillary anterior teeth. Any deviation from these guidelines may result in unappealing and anesthetic appearance.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Humagain M, Rokaya D, Srii R, Dixit S, Kafle D. Gender based comparison of gingival zenith esthetics. Kathmandu Univ Med J 2016;14:148.  Back to cited text no. 14
    
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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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