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DENTAL SCIENCE - ORIGINAL ARTICLE
Year : 2015  |  Volume : 7  |  Issue : 6  |  Page : 486-490  

Gender identification and morphologic classification of tooth, arch and palatal forms in Saudi population


Department of Prosthetic and Restorative Dental Sciences, College of Dentistry, Hail University, Kingdom of Saudi Arabia

Date of Submission28-Apr-2015
Date of Decision28-Apr-2015
Date of Acceptance22-May-2015
Date of Web Publication1-Sep-2015

Correspondence Address:
Dr. Pavankumar Ravi Koralakunte
Department of Prosthetic and Restorative Dental Sciences, College of Dentistry, Hail University
Kingdom of Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-7406.163510

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   Abstract 

Aims: To determine various tooth form, arch form, and palatal form with gender identification between males and females of the Saudi population. Materials and Methods: Irreversible hydrocolloid impressions were made of the maxillary teeth of 100 dentate male and female subjects to obtain study casts. A standardized procedure was adopted to photograph the maxillary dental arches and the maxillary central incisors on the study casts taken from each subject. The outline form of tooth, arch, and palatal form were determined using a standardized method. The average of six prosthodontist's evaluation was considered who classified the outline tracings visually. The statistical analysis was performed using Chi-Square and results tabulated. Results: The predominant tooth is combination form in males and ovoid form in females, the predominant arch is ovoid form in males and square form in females and the predominant palatal form are both U and V shaped in males and U-shaped in females. Conclusion: Except for the tooth form there was a significant difference with arch and palatal form among males and females of the population group studied. The determined tooth, arch and palatal forms are useful in selection and arrangement of artificial teeth among Saudi edentulous population group. Generalizing from the study is questionable as the sample size is small. Further studies should be conducted in a larger sample to confirm the study results

Keywords: Maxillary arch form, maxillary central incisor tooth form, palatal form, palatal vault


How to cite this article:
Mohammad A, Koralakunte PR. Gender identification and morphologic classification of tooth, arch and palatal forms in Saudi population. J Pharm Bioall Sci 2015;7, Suppl S2:486-90

How to cite this URL:
Mohammad A, Koralakunte PR. Gender identification and morphologic classification of tooth, arch and palatal forms in Saudi population. J Pharm Bioall Sci [serial online] 2015 [cited 2019 Aug 21];7, Suppl S2:486-90. Available from: http://www.jpbsonline.org/text.asp?2015/7/6/486/163510

Facial esthetics has important social and psychological effects on the human personality in which the appearance of anterior teeth is critical for an attractive face and pleasing smile. Thus, dental and facial esthetics is the common aim for all patients seeking dental treatment. [1] When only parts of the dentition have to be restored, the remaining natural dentition can serve as a guide. However, in cases where the entire dentition has to be restored and no information can be gained from remaining natural teeth, old photographs, or cast models, other methods have to be applied to select and design the missing teeth. One of the most crucial parameters in this context is in selecting the correct shape and size of the maxillary anterior teeth. [2]

The review of the dental literature reveals several factors, methods, techniques and theories that have been suggested as aids for artificial tooth selection. [3] The most universally accepted "Law of Harmony" was stated by James Leon William [4] 1914 who hypothesized the relation between the form of inverted maxillary central incisor and the face form. Numerous studies [1],[4],[5] have been conducted on various population groups based on William's geometric theory to evaluate the correlation between the tooth form and the face form. Among which some studies proved [6],[7] with positive results while many others [8],[9],[10] disproved, which may be attributed due to racial and gender differences. [2],[11],[12],[13]

In prosthetic dentistry, sex-related differences in tooth forms and arrangement of anterior teeth are assumed, and optimal esthetics is also assumed to be achieved only if the face, arch, and tooth forms are in harmony. Furthermore, these forms are classified as square, tapering or ovoid by use of basic geometric shapes along with additional combination forms. [14] Nelson s [15] "esthetic triangle" theory proposed a close relationship between face, tooth, arch, and alignment but the studies revealed insignificant correlation and was not highly defined. [1],[14]

Currently, there is no such universally accepted single esthetic factor that can be reliably used in artificial tooth selection. Furthermore, among Saudi population, there is a lack of research evidence pertaining to factors related to artificial tooth selection for edentulous patients. So, the present clinical study was conducted to classify various anterior tooth forms, arch forms and palatal forms with its predominant occurrence in both males and females of the Saudi population. The results thus obtained would be used as guidelines during the selection of teeth, the arrangement of teeth among edentulous patients of the Saudi population for esthetically pleasing fixed and removable dental prosthesis.


   Materials and Methods Top


A total of 100 dentate dental students of which 50 males and 50 females aged between 20 and 25 years were randomly selected as representative of the young adult group. The selected students had no restorations in the anterior teeth and had not received orthodontic treatment. The clinical research study was conducted after explaining the student subjects in their own language along with a signed written consent approved by the Institutional Ethical Committee.

An impression of each student's maxillary dentition was made with irreversible hydrocolloid impression material of 50 male and 50 female subjects to obtain study casts poured with dental plaster. Additional duplicated sectional study casts were obtained to aid in identification and classification of the palatal form.

A standardized procedure was adopted to obtain digital photograph of the maxillary central incisors, the maxillary dental arch from the study casts [Figure 1] and [Figure 2] and the palatal contour from the duplicated sectional casts using Nikon Coolpix digital camera (S3400; Nikon Corp. Japan). The photographs were then transferred to a computer (Windows PC, Microsoft) having image editing software (Photoshop 6.0 Adobe, Nikon Corp. Japan) to obtain individual photographic tracing printouts of the tooth form, arch form and the palatal form for evaluation by visual method. [1],[14]
Figure 1: Frontal photograph of the maxillary incisor teeth

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Figure 2: Occlusal photograph of the maxillary dental arch

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The tooth form was determined on the right maxillary central incisor tooth by an outline tracing made around the buccal surface of the tooth, which corresponded to the mesial and distal contours, the incisal edge and the cervical margin. The photographic printouts of the tracing had a diagram of perpendicular lines that was placed on the tooth form outline tracing [Figure 3] and the tooth in each quadrant was classified visually according to William's as follows:

  • Square incisor tooth - mesial and distal proximal surfaces are parallel for at least half of the cervicoincisal length of the crown
  • Ovoid incisor tooth - mesial and distal proximal surfaces are biconvex
  • Tapering incisor tooth - mesial and distal proximal surfaces converge from incisal to cervical.


Figure 3: Tracing printout of the maxillary incisor tooth form

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One of the three basic tooth forms (square, ovoid or tapering) was classified to a tooth only if that form predominated in at least 75% of the outline tracing print (three quadrants). If one of the basic form predominated in at least 50% of the outline tracing print (two quadrants), the tooth form should be classified as a combination tooth form. [12],[16]

The arch form was determined on the maxillary arch by an outline tracing made around the arch corresponding to the incisal edges of the incisors, canine cusp tips, buccal cusps tips of premolars and molars. The photographic printouts [Figure 4] of the tracing were used to classify the arch form visually as square, ovoid or tapering. [1]
Figure 4: Tracing printout of the maxillary arch form

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The palatal form was determined by a contour tracing made along the surface of the maxillary cast with a deep midpoint marked along the mid palatal suture that joins the palatal cusps of two selected premolar or molar teeth. The photographic printouts [Figure 5] of the tracing were used to classify the palatal form visually as U-shaped, V-shaped or shallow. [17],[18]
Figure 5: Tracing printout of the palatal form

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Six prosthodontists with more than 5 years of experience classified the photographic outline tracings of the tooth, arch and palatal forms visually based on the instructions obtained before evaluation. The means of prosthodontists evaluation were considered and statistically analyzed using Chi-Square test for distribution differences and results were tabulated.


   Results Top


The following results were tabulated:

The combination tooth form 44% predominated in males followed by square 28%, ovoid 14% and tapering 14% tooth forms when compared with the ovoid tooth form 36% predominated in females, followed by combination 32%, square 24% and tapering 8% tooth forms [Table 1]. The χ2 = 6.759 was found to be not significant with a P = 0.080.
Table 1: Descriptive statistics for comparison of predominant maxillary central incisor tooth form in males and females of Saudi population

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The ovoid arch form 42% predominated in males followed by tapering 36% and square 22% arch forms when compared with the square arch form 44% predominated in females followed by ovoid 40% and tapering 16% arch forms [Table 2]. The χ2 = 7.537 was found to be significant with a P = 0.023.
Table 2: Descriptive statistics for comparison of predominant maxillary arch form in males and females of Saudi population

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The U-shaped and V-shaped palatal forms 46% respectively predominated in males followed by shallow palatal form 8% when compared with the U-shaped palatal form 74% predominated in females followed by V-shaped 14% and shallow 12% palatal forms [Table 3]. The χ2 = 12.20 was found to be significant with a P = 0.002.
Table 3: Descriptive statistics for comparison of predominant palatal form in males and females of Saudi population

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   Discussion Top


The size and form of the maxillary anterior teeth are important to not only dental, but also facial esthetics. The most influential factors contributing to a harmonious anterior dentition are the size, shape, and arrangement of the maxillary anterior teeth, particularly the maxillary central incisors as viewed from the front. [11] According to the glossary of prosthodontics terms (GPT 8), anterior tooth form is defined as "the outline form as viewed in any selected plane or/and other contours of an anterior tooth". [19] In the present study, outline form of the maxillary right central incisor tooth was considered to classify according to Williams method of classification of tooth forms into square, ovoid, tapering or combination tooth forms.

The dentulous arch form of an individual will remain the same even after becoming an edentulous arch and that the edentulous arch remains fairly constant in the absence of surgical intervention. Boucher is of the same opinion that the original form of the dental arch is maintained even after the removal of natural teeth. [20] The arch form is defined according to GPT 8 as "the geometric shape of the dental arch when viewed in the horizontal plane (square, tapering, ovoid, etc.)". [19] In 1932, Chuck [21] classified the arch forms as tapered, ovoid and square for the first time which can also be expressed as narrow, normal and wide respectively. In the present study, the maxillary arch form was classified as square, ovoid and tapering arch forms.

The hard palate is the bony portion that forms the roof of the mouth. The form of the palatal vault or depth of the hard palate gives an idea about the original form of the dental arch before removal of the natural teeth and resorption of the residual ridge. [17] The palatal vault is defined according to GPT 8 as "the deepest and most superior part of the palate or the curvature of the palate". [19] The palatal vault is classified as low palate, medium palate and high/deep palate, which can also be expressed as shallow/flat palate, U-shaped palate and V-shaped palate respectively. [22] In this study, the palatal form or palatal shape was classified as U-shaped, V-shaped or shallow palatal forms.

The predominant tooth form for males in the present study was combination tooth form 44% followed by square 28%, ovoid 14% and tapering 14% tooth forms. The value was lesser when compared with the previous study being combination tooth form 58%, followed by square 22%, tapering 13% and ovoid 8% tooth forms. [23]

The predominant tooth form for females in the present study was ovoid tooth form 36% followed by combination 32%, square 24% and tapering 8% tooth forms. This was in correlation with the previous study being ovoid teeth for females but the value was higher and not in correlation when compared with the previous study being predominant combination tooth form 51%, followed by square 22%, ovoid 15% and tapering 12% tooth forms. [23],[24]

The predominant arch form for males in the present study was ovoid arch form 42% followed by tapering 36% and square 22% arch forms. The value was lesser when compared with the previous study being ovoid arch form 66.7% followed by tapering 33.3% arch forms. [25] The value was not in correlation when compared with the previous study being predominant narrow (tapering) arch form 13.5% followed by flat 10.5%, wide (square) 10.3%, pointed 8.3% and mid (ovoid) 7% arch forms. [26] The value was lesser when compared with the previous study being ovoid arch form 55.1%, followed by tapering 54.2% and square 42% arch forms. [27] The value was higher and not in correlation when compared with the previous study being predominant square arch form 35.33%, followed by ovoid 34.67% and tapering 30% arch forms. [20]

The predominant arch form for females in the present study was square arch form 44%, followed by ovoid 40% and tapering 16% arch forms. The value was lesser when compared with the previous study being square arch form 58%, followed by tapering 45.8% and ovoid 44.9% arch forms. [27] The value was not in correlation when compared with the previous study being predominant narrow (tapering) arch form 17.4%, followed by wide (square) 13.6%, pointed 9.3%, flat 7.8%, and mid (ovoid) 2.3% arch forms. [26] The value was higher when compared with the previous study being square arch form 36.67% followed by ovoid 33.33% and tapering 30% arch forms. [20]

The predominant palatal form for males in the present study was both U and V shaped palatal forms 46% respectively, followed by shallow 8% palatal form. This was in correlation with the previous study that the palatal depth is significantly higher in males. [17]

The predominant palatal form for females in the present study was U-shaped palatal form 74% followed by V-shaped 14% and shallow 12% palatal forms. This was in correlation with the previous study that the palatal depth significantly is not higher in females. [17]

The palatal form value in the present study for both males and females combined was higher and not in correlation when compared with the previous study based on qualitative method of palatal depth assessment being predominant low palate (shallow) 51.4% followed by medium palate (U-shaped) 43.2% and high palate (V-shaped) 5.4% palatal forms but the value was higher and in correlation when compared with quantitative method of palatal depth assessment being predominant medium palate (U-shaped) 55.4% followed by high palate (V-shaped) 39.2% and low palate (shallow) 5.4% palatal forms. [22]


   Conclusion Top


Within the limitations of the Saudi population group studied, the following inferences may be drawn:

  • The predominant tooth form was combination tooth in males and ovoid tooth in females
  • The predominant arch form was ovoid arch in males and square arch in females
  • The predominant palatal form was both U and V shaped (medium and deep palates) in males, and only U-shaped (medium palate) in females
  • Except for the tooth form, there was a significant difference with arch and palatal form among males and females of the population group studied.


Thus during selection and arrangement of artificial teeth for edentulous Saudi patients, the dentist and the laboratory technician will require basic tooth forms (square, ovoid and tapering) along with combination tooth forms. Individual patient's preferences during the selection and arrangement of anterior teeth should also be considered to increase the success rate of fixed and removable dental prosthetic treatment. However, generalizing from the present study is questionable as the sample size is small. Further studies should be done in a larger sample to confirm the study results.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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