|Year : 2016 | Volume
| Issue : 2 | Page : 64-70
Evaluating the reliability of the interalar width and intercommissural width as guides in selection of artificial maxillary anterior teeth: A clinical study
Glynis Anita Miranda1, Mariette D'Souza2
1 Department of Prosthodontics, AJ Institute of Dental Sciences, Mangalore, India
2 Private Practitioner, Udupi, Karnataka, India
|Date of Web Publication||5-Jan-2017|
Glynis Anita Miranda
Department of Prosthodontics, AJ Institute of Dental Sciences, Mangalore
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objective: Oral rehabilitation of a completely edentulous patient is essential to improve the patients self-esteem and self-confidence through the fabrication of conventional or implant supported overdentures. To achieve this, there is a need to restore the natural appearance of the patient through appropriate anterior tooth selection which requires reliable guidelines. Thus, the objective of this study was to determine the correlation and evaluate the reliability of the interalar width to intercanine distance and intercommissural distance to the distal aspects of the canines in the selection of maxillary anterior teeth. Materials and Methods: Two-hundred individuals who satisfied the inclusion and exclusion criteria were selected. The four parameters such as interalar width, intercanine distance, intercommissural width, and distance between distal aspects of canines were measured. The data obtained were statistically analyzed. Results: The results revealed that the mean values for interalar width and intercanine distance in males were 3.852 and 3.538 cm, respectively, and in females, it was 3.396 and 3.402 cm, respectively. In addition, the mean values for intercommissural width and distance between the distal aspects of canines were 4.921 and 3.913 cm in males, respectively. In females, it was 4.590 and 3.740 cm, respectively. In males and females, the correlation between interalar width and the difference between the intercanine distance and interalar width is statistically highly significant (in males r = 0.707, in females r = 0.619). Correlation of difference of intercommissural width and the distance between the distal aspects of the canines with the average of intercommissural width is statistically significant (in males r = 0.777, in females r = 0.712). Conclusion: A correlation was observed between the interalar distance and the intercanine distance and also between the intercommissural distance and the distance between the distal aspects of canines.
Clinical Relevance To Interdisciplinary Dentistry
- It is the dentists' responsibility to preserve the natural dignity of advancing age while fabricating a complete denture prosthesis, with appropriate and careful selection and arrangement of teeth
- As it is difficult to determine the dimensions of the maxillary anterior teeth for an edentulous patient when preextraction records are not available, other guidelines must be taken into consideration and the development and implementation of an esthetic proforma to guide the dentist and patient may be essential
- One area of prime concern may be to determine correlations and relationships between interalar width and intercommissural width with the mesiodistal width of upper anterior teeth which can be interpreted as a useful guide in clinical practice.
Keywords: Anterior teeth selection, esthetics, interalar width, intercanine distance, intercommissural width
|How to cite this article:|
Miranda GA, D'Souza M. Evaluating the reliability of the interalar width and intercommissural width as guides in selection of artificial maxillary anterior teeth: A clinical study. J Interdiscip Dentistry 2016;6:64-70
|How to cite this URL:|
Miranda GA, D'Souza M. Evaluating the reliability of the interalar width and intercommissural width as guides in selection of artificial maxillary anterior teeth: A clinical study. J Interdiscip Dentistry [serial online] 2016 [cited 2019 Sep 15];6:64-70. Available from: http://www.jidonline.com/text.asp?2016/6/2/64/197665
| Introduction|| |
Acomplete denture is perceived esthetically pleasing and functionally acceptable when the teeth are placed and arranged in a biologic harmony with the surrounding tissues.  The arrangement and alignment of anterior teeth have always remained as a challenging experience to the dentist since phonetic values, esthetics, and also function have to be considered simultaneously. The denture bases and the selection of the artificial teeth should be in harmony with the facial musculature as well as the shape and size of the head.  Moreover, Boucher had averred that the correct positioning of an artificial tooth is actually the one in which it was placed by nature. 
Preextraction records such as photographs, radiographs, and extracted teeth do play an important role in the selection of teeth with reference to shape, size, and color. With no preextraction records available, selecting the proper anterior teeth size for edentulous patients can be arduous. , Therefore a systematic approach is needed in such situations; consequently, several anatomic measurements have been suggested including bizygomatic width, intercommissural width, interalar width, and interpupillary distance. , The so-called "denture look" will be reflected on the face when these guidelines have been failed to be used though it may have a satisfactory appearance on the articulator. Furthermore, one of the critical factors is the position of the canine in denture teeth arrangement since it provides tissue support at the corner of the mouth and its position is in the turning point of the dental arch.  "Nasal index," a popular guide in selection of anterior teeth, is actually an index that relates the interalar width to the space available for setting upper anterior teeth and, by implication, the width of teeth when selecting a tooth mold.  The interalar distance supposedly represents the distance between the cuspid tips. The intercommissural method is based on the hypothesis that the distal surface of the maxillary canines should be located approximately at the commissures of the mouth.
The rationale behind this research depends on the acceptance of the postulate that artificial anterior teeth should be arranged in the same position as their natural predecessors and also be analogous in size and shape. Hence, an investigation of the relation between the width of the nose, intercommissural width, and the natural teeth was undertaken.
| Materials And Methods|| |
The study was conducted to compare and evaluate the relationship between the interalar width to the intercanine distance and the intercommissural width to the distance between the distal surfaces of the maxillary canines in the male and female groups.
A total of 200 dentulous individuals were chosen for this study. The sample comprised 100 males and 100 females ranging in age from 20 to 30 years. The sample was grouped by gender to determine the effect of this factor on the correlations of the measurements.
Selection of individuals was based on the following criteria:
- Inclusion criteria:
- All cases were above 18 years of age so that growth of the face was essentially complete
- Cases who had normal occlusion with full complement of natural teeth.
- Exclusion criteria:
- Individuals with proximal restorations on the distal surfaces of canine that could grossly affect the width of maxillary anterior teeth
- Individuals who had spacing or crowding of maxillary anterior teeth were excluded
- Individuals with congenital or developmental deformities (abnormal or altered nose) and had undergone any surgical repair in the orofacial region
- Individuals treated orthodontically or proximal stripping were excluded
- Individuals with developmental anomalies of the maxillary anterior teeth and deciduous canines were excluded
- No individuals were included with atypical condition such as traumatized lips and mobile anterior teeth.
The individual should have an apparently normal face form as determined by the vermilion border of lips, the nasolabial fold, the philtrum, and the labiomental fold. By "normal" it is meant that these factors did not by themselves bring undue attention to the individual.
A proforma specially designed for the project was filled out for each individual. Both extraoral and intraoral examinations were done. Informed consent was taken for using their data in the research.
| Procedure|| |
The individual was seated on the dental chair comfortably, in a relaxed state and upright position. The proforma was filled out for each individual and selection was done according to the criteria laid down for the study. The interalar width and the intercommissural distance were measured using a Vernier Caliper. An impression of the maxillary cast was made and the cast was poured. On the cast, the intercanine distance and the distance between the distal aspects (distal contact point) of the canines in a straight line were measured. These measurements were done on accurate stone casts instead of directly in the mouth because measurements can be repeated more conveniently on casts than in mouth. The results obtained were then compared to find out the accuracy of maxillary artificial anterior teeth selection.
Recording the interalar width
The individual was seated on the dental chair in a relaxed state and in an upright position. Two points were marked on either side of the nose with a fine tipped marking pen indicating widest points on the outer surfaces of the alae of the nose. The distance between the two points marked on the alae of the nose was recorded using a pair of Vernier Calipers by bringing the recording parts of the gauge just in contact with the outer surfaces of the alae, without any pressure being applied [Figure 1]. While measuring, the patient was asked to stop breathing momentarily to avoid any change in shape of the nose. The readings on the Vernier scale were noted down to the fraction of one tenth of a millimeter. The readings were repeated three times and the mean was recorded.
|Figure 1: Recording the interalar width at the widest dimension of the nose|
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Determination of intercommissural width
With the individual in a relaxed state, the distance was measured between the two points marked at the commissure in its passive state with a pair of Vernier Calipers [Figure 2]. Extreme care and attention were given to prevent any change in position of commissure consequent to changes in facial expression. The readings on the Vernier scale were noted to the fraction of one tenth of a millimeter. Three such recordings were made to arrive at an average value.
Preparation of maxillary cast
A perforated stock metal tray of an appropriate size was selected to record the complete complement of natural maxillary teeth. An irreversible hydrocolloid impression material was used as per the manufacturer's instructions. The impression obtained was inspected and if found suitable, was thoroughly washed under running water and then poured immediately with dental stone. To avoid inaccuracies, the same make of stone and water-powder ratio was used. Care was taken to prevent incorporation of air bubbles using a mechanical vibrator to pour the casts.
Measurement of intercanine distance and the distance between the distal aspects of the canines
A small dot was marked on the tips of the canines. A Vernier Caliper was used to check the distance between the dots. Thus, the intercanine distance, a straight distance between the tips of the canines, was measured to the fraction of one-tenth of a millimeter [Figure 3]. In individuals where a distinct cusp tip was not noticeable due to attrition, the midpoint of the wear facet was taken for recording the intercanine width. Each dot was equidistant from the mesial and distal margins and from the buccal and palatal margins. Three readings were recorded and the average value was taken as the final intercanine distance. To determine the distance between the distal surfaces of the canines, the recording parts of the Vernier Caliper were placed on the distal surfaces of the canines at the contact point and this distance was measured to the fraction of one-tenth of a millimeter [Figure 4]. Each recording was repeated three times to standardize the measurements.
|Figure 4: Recording the distance between the distal aspects of the canines|
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For sake of consistency, the same examiner made all of the records, performed all of the measurements, and recorded all of the information.
A statistical evaluation was done on the basis of the data that was obtained from the 200 samples.
| Results|| |
Measurements obtained from the 200 individuals were tabulated. In this study, a statistical significance was determined using the t-test. There was a statistically significant difference in the values of the measured parameters between the male and female individuals. The investigated parametric interconnection was analyzed by linear correlative analysis (Pearson's analysis) and numerically presented by the linear correlation coefficient (r). The present sample revealed increased values of interalar width and intercommissural width values for males than females [Graph 1]. Equivocal reports also exist in literature. , Thus, it appears that men have wider noses and greater intercanine distances than women. The parameters when compared between the gender groups were found to be statistically very highly significant (P = 0.001) as shown in [Table 1] and [Table 2].
|Table 1: Comparison of the various parameters with gender using Descriptive statistics and Student's unpaired t-test |
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|Table 2: Mean difference of the various parameters in males and females |
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The mean values for interalar width and intercanine distance in males were 3.852 and 3.538 cm, respectively, and the mean values for intercommissural width and distance between the distal aspects of canines were 4.921 and 3.913 cm, respectively. In females, the mean values for interalar width, intercanine width, intercommissural width, and distance between the distal aspects of canines were 3.396, 3.402, 4.590, and 3.740 cm, respectively.
The coefficient of correlation "r" was calculated to determine the relationship between the following [Table 3]a and b:
- Interalar width and the difference between the interalar width and the intercanine distance
- Intercommissural width and the difference between the distal aspects of canine and intercommissural width.
In males and females, the correlation between interalar width and the difference between the intercanine distance and interalar width is statistically very highly significant. In males, "r" value is 0.707 and P value is 0.001. In females, the "r" value is 0.619 with P value of 0.001 that is highly significant. In addition, the correlation value between the intercommissural width and the difference between the intercommissural width and the distance between the distal surfaces of the canines in males is found to be statistically highly significant (r = 0.777, P = 0.001). In females, the "r" value for correlating intercommissural width to the difference between distal surfaces of canines and the intercommissural width is statistically significant (r = 0.712, P = 0.001).
| Discussion|| |
Many techniques of anterior teeth selection exist, but little consensus on an effective and valuable method has been attained. This study was therefore done to ascertain the validity of interalar width and intercommissural width as guides in the selection of upper anterior teeth. Literature has shown that the distance between the outer surfaces of the alae of the nose nearly corresponds to that between the tips of the canines. ,,,,
Of several methods, the mesiodistal dimension of anterior teeth can be related to the distance between the corners of the mouth as pointed out by Silverman and also to the width of the nose as suggested by Lee. 
In this study, the interalar width of the nose, a standard anthropometric measurement, was measured at the widest points between the outer surfaces of the alae of the nose. The intercommissural width was measured between the corners of the mouth. The intercanine distance and the distance between the distal surfaces of the canines were obtained from stone casts.
Hoffman et al.  and Scandrett et al.  measured the distance between the distal surfaces of the canines in a circumferential arc. This is probably because the anterior teeth are classified by the distance from the distal surface of one maxillary canine to the distal surface of the opposite canine. However, the present study measured the distance between the distal surfaces of canine in a straight line. Proclination and retroclination of the anteriors may have an influence on the circumferential measurement whereas a linear measurement would be more reliable. Moreover, the mesiodistal measurement may be dependent on the level at which the measurement was made, i.e., circumferential measurement made at a cervical level or incisal level may be more or less depending on the angulation of teeth. The variations noted in the values of the intercommissural widths and distal surfaces of canines, in this study, may be attributed to the disto-palatal rotation of the canine that is inherent in most natural dentitons. Mavroskoufis and Ritchie  and Ahn et al.  in their study also measured the intercanine distance in a straight line.
The current study revealed an average interalar width as 3.852 cm in males and 3.396 cm in females. The values showed that the interalar width was lesser in females by 0.456 cm (4.56 mm), revealing an influence of sex factor and this finding is in conformity with concepts of Frush and Fisher.  Smith,  Dharap and Tanuseputro,  Keng,  and Ahn et al.  in their studies had also observed an influence of sex factor. Their results also showed that males have wider noses than females.
The average intercanine distance in males was 3.538 cm and in females was 3.402 cm. This revealed that the intercanine distance was less in females by 0.136 cm. This may be due to the differences in the size of the arch and teeth in the two genders.
The intercommissural width in males was 0.331 cm greater than in females. The mean intercommissural measurement for males was 4.921 cm and for females 4.590 cm. Lieb et al.  in their study showed that the average distance through the commissures was 5.27 cm. In their study, the variations in measurements can be attributed to ethnicity.
The distance between the distal surfaces of the canines was also greater in males by 0.173 cm (1.73 mm), indicating that males have wider arches than females.
In the current study, all measurements are greater in males revealing the influence of sex factor in accordance to the dentogenic concept.
Many are of the belief that the interalar width is comparatively similar to the intercanine distance and this decisive factor is one of the criteria for the selection and placement of the upper six anterior teeth. However, this standard approach is not always to be followed as a general rule because sometimes there is variance in the measurements between the variables compared in some individuals. In the present study, from the mean values estimated, the average interalar width in males was more nearer to the measurement of the distance between the distal surfaces of the canines, rather than to the intercanine distance. However, in females, the interalar width value was found to be nearer to the intercanine distance.
In studies where clinical measurements are considered, comparison of a new measurement technique with an established one is often indispensable to see whether they agree or correlate sufficiently for the new technique to replace the old one. Using correlation coefficient, notably, these investigations are often analyzed inappropriately. The correlation coefficient "r" measures the degree of association or strength of linear association between two quantities and not how strongly they agree.  Therefore, when comparing a new method of measurement with an established one, we need to know whether the difference between the two methods is related to the magnitude of measurement and thus a plot of difference against standard measurement when carried out will show whether there will be a true association or not, between the difference and the magnitude.
In this study, when difference was plotted against the average of the standard measurement, a positive correlation was observed between the variables that were compared in both groups indicating that they can be used as useful guides. Keng  in his study found no demonstrable correlation between interalar width and intercanine distance. He concluded that men had wider noses and slightly greater intercanine distances compared to women. The results of this study were in conformity with the latter findings of Keng. Lieb et al.  observed some correlation between intercanine distance and intercommissural width, but certainly not high enough to be used as a predictive factor. The correlation coefficient was + 0.45 and they concluded that the cuspid tooth does not have any consistent pattern of relationship to anatomic facial features. Scandrett et al.  opined in their study that intercommissural width had the greatest correlation, 0.44, with the width of the maxillary anterior teeth.
Further studies can be carried out on dentulous individuals of different age groups, i.e., middle-aged and older, to compare the clinical findings. The results of this study may not be applicable to all age groups. Smith from his study concluded that there is an increase in the interalar width with age in both men and women.
As age advances, tissues get laxed and this loss in tonicity of muscles leads to erroneous values, i.e., interalar width is seen to increase generally but that does not indicate bigger teeth for older individuals. Aged dentitions also show physiologic or pathologic drifting of teeth that may cause a difference in values. Therefore, much emphasis on the importance of preextraction records is essential, to facilitate anterior tooth selection during complete denture fabrication.
| Conclusion|| |
From the results of this study, the following conclusions can be drawn:
- All the measurements made were more in males than females, thus indicating an influence of gender factor
- In males, there was a tendency of interalar width being greater than the intercanine distance while the reverse situation existed in females where the intercanine distance tended to be greater than the interalar width
- A correlation between the interalar width and intercanine distance was observed in both gender groups
- A correlation was also observed between the intercommissural width and the distance between the distal surfaces of the canines in both groups.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]