INTRODUCTION
The comfort, function, and esthetics must be restored altogether while treating a completely edentulous patient. One of the main objectives in selecting and arranging artificial teeth is to produce a prosthesis that defies detection.1 The anterior teeth are the ones primarily selected to satisfy esthetics. The selection requires scientific knowledge as well as artistic skill of the dentist. Teeth that are of a proper size are essential in achieving a natural looking denture.2-5 Patients requiring complete dentures usually expect comfort first, followed by harmonious appearance and efficiency. Besides, on receiving their first dentures, patients often expect to appear similar to when they had their natural teeth. Therefore, correct selection of artificial teeth is essential to achieve a pleasant esthetic outcome.6-10 The width of the maxillary anteriors is difficult to correlate with the facial measurements than the height of the maxillary anteriors. In addition, the generation approaching 70 years of age recognizes that maintaining their natural dentition improves appearance and smile and serves as a visible sign of successful aging.11,12 Many efforts have been made to accurately quantify the selection of the anterior teeth. Some of the more familiar ones are BW, IPD, ICD, IAD, and ICOW), and some newer anatomical measurements, such as philtral width, pterygomaxillary notch (PMN), circumference of skull (COS), maxillary arch length (MAL), and maxillary arch width (MAW) have also been studied. However, little agreement on an effective method has been reached. There is no consensus of data regarding a single esthetic factor that can be used reliably as an aid for artificial tooth selection.13-19 Hence, this systematic review was carried out to try and identify a single, reliable anthropometric measurement that can be used to determine the size of the anterior teeth in various population groups.
Aim
The aim of this systematic review was to evaluate which anthropometric measurement is the most reliable indicator to determine the width of the maxillary anterior teeth in various population groups.
Null Hypothesis
There is no reliable anthropometric measurement to determine the width of maxillary anterior teeth.
MATERIALS AND METHODS
Sources used
An electronic search was conducted for scholarly articles discussing various anthropometric measurements used for determination of width of maxillary anterior teeth, written in English or translated into English, listed with PubMed, Cochrane Library, ScienceDirect, Wiley Online Library, and Google Scholar databases.
Population, Intervention, Comparision, and Outcome Analysis
Search Methodology
The search strategy yielded 119 articles. Of them, 70 were excluded following reading the extract, and 49 were selected for full-text reading. Of these 21 were excluded based on exclusion criteria. Finally, 28 articles were included for final search. Data extraction was done from the selected articles. The extracted data were analyzed statistically.
Population
The study population included patients undergoing replacement of missing anterior teeth/posterior teeth from different population groups: Such as adult human beings, dentulous mouth, male, female, Indian adults, South Indian adults, Brazilian ethnology, European ancestry, Asian continental ancestry group, African continental ancestry group, Canadian population, Arab population, and Saudi population.
Intervention
Various anthropometric measurements were taken: IPD, ICD, nose width, combined width of maxillary anterior teeth, IAD, ICOW, BW, circumference of head, anterior teeth width, facial width, mouth width, bridge of the nose width, base of the nose width, maxillary central incisor width (CIW), cervical width of maxillary central incisor, contact point width of maxillary central incisor, incisal width of maxillary central incisor, arch length, and arch width.
Outcome
Significant estimation and correlation between IPD, ICD, nose width, IAD, ICOW, BW, circumference of head, facial width, mouth width, bridge of the nose width, base of the nose width, arch length, arch width with maxillary CIW, and combined width of maxillary anterior teeth was determined.
Variables of Interest
Correlation between the anthropometric measurement and width of the maxillary anterior teeth was considered significant to be determined.
Selection of Studies
The review process consisted of two phases. In the first phase, titles and abstract of the search were initially screened for relevance and the full text of relevant abstract were obtained and accessed. The hand search of selected journals as well as search of references in the selected studies was also done. The articles that were obtained after first step of review process using the following inclusion and exclusion criteria were screened in second phase and relevant and suitable articles were isolated for further processing and data extraction. There were no language restrictions.
Inclusion Criteria
The articles discussing the following parameters were included for systematic review.
Types of Participants
Dentulous subjects with natural permanent maxillary teeth in good alignment
Subjects with Angle's Class I molar and canine relationships
Patients with no history of orthodontic treatment or extraction
Subjects whose teeth were morphologically normal
Patients above 18 years of age, so facial growth was completed
Dentate individuals from various population groups, such as Brazilians, Indians, Chinese, Caucasians, blacks, and Mulattos.
RESULTS
Among 28 articles which were included for final search, data extraction was done from the selected articles and was analyzed statistically. Indian population showed the highest correlation with IAD***, mainly South Indian females with square-shaped arch (r = 0.52), followed by North Indian females (r = 0.457), and least correlation was found in Asian population (r = 0.089), whereas negative correlation was seen in Aryans (r = –0342) and Mongoloids (r = –0.217) (Graph 1). Saudi population showed the highest correlation with ICD (r = 0.932), whereas Indian population (Thrissur, Kerala) showed the least correlation (r = 0.033) (Graph 2). Indian population showed highest correlation with IPD as well, mainly Indian males (r = 0.809) followed by Indian females (r = 0.726), and least correlation was found in Caucasian population (r = 0.15), whereas negative correlation was found in Aryans (r = –0.38) and Mongoloids (r = –0.439) (Graph 3). Mulatto (r = 0.518) and blacks (r = 0.516) showed the highest correlation with ICOW, whereas Caucasians (r = 0.16) showed least correlation, and Aryans (r = –0.337) and Mongoloids (r = –0.316) showed negative correlation (Graph 4). Indian population showed the highest correlation with BW, mainly Indian males (r = 0.50) followed by Indian females (r = 0.447), and least correlation was found in British population (r = 0.29) (Graph 5).
DISCUSSION
In case of absence of preextraction records, selection of upper anterior artificial teeth for edentulous patients is difficult. According to professional sources, a scientific and universally accepted method for accurately determining the mesiodistal width of anterior artificial teeth has not yet been found. Discussions on this topic are present in the contemporary professional literature.20-28 Reviews of the recent scientific literature reveal studies that were carried out using different methodology and sample size, different face and natural teeth parameters,8,10-13,15,19,20 casts,5,16-18,21,22 or photographs,5,14,16,17,20 as well as various types of gauge which make the comparison of results very difficult. The authors here used a variety of instruments to determine the measurements. The instruments varied from a traditional Boley's guage, digital Vernier calipers, Willis Guage, War wins foldable scale, modified dividers, and flexible rulers to an image processing software (HL Image).
Out of 28 finally selected articles, 15 articles studied the IAD as an anthropometric parameter in determining the width of the maxillary anteriors, of which only 13 articles were studied because in 2 studies correlation coefficient was not mentioned. The population groups included in the studies were Aryans, Mongoloids, Indians, Serbian, Caucasians, White, Mulatto, Asian, Blacks, Brazilian, Saudi, and Malaysians. When the CIW was correlated with IAD, Caucasians showed greater correlation (r = 0.21)13 than Serbian adults (r = 0.12).9 When maxillary anterior teeth width was correlated with IAD, Indian population showed the highest correlation with IAD, mainly South Indian females with square-shaped arch (r = 0.52)16 followed by North Indian females (r = 0.457),14 and the least correlation was found in Asian population (r = 0.089),21 whereas negative correlation was seen in Aryans (r = –0342) and Mangoloids (r = –0.217).5 Facial proportions can vary in different ethnic groups.13,28 South Indian population has the highest correlation with IAD, which could be due to Dravidian ethnic group. Dravidians are one of the non-Aryan races of Southeast Asia and are distributed mainly in South India with dominant characteristics of the faces with wider nasal width. Epicanthic folds and oblique palpebral fissures are common among Mongoloid individuals. Mongoloid individuals have straight, black hair and dark brown almond-shaped eyes, and have broad, relatively flat faces which could be the reason for weak and negative correlation.
Fourteen articles studied the ICD as an anthropometric parameter in determining the width of the maxillary anterior, of which only 12 articles were studied because in 2 studies correlation coefficient was not mentioned. The population groups included in the studies were Aryans, Mongoloids, Indians, Caucasians, Brazilian, Saudi, and Arab. When the CIW was correlated with ICD, Caucasians showed weaker correlation (r = 0.12)13 than Serbian adults (r = 0.13).9 When maxillary anterior teeth width was correlated with ICD, Saudi population showed the highest correlation with ICD (r = 0.932),24 followed by Indian population (r = 0.757),7 whereas in another study, Indian population (Thrissur, Kerala) showed the least correlation (r = 0.033),3 this could be due to people with Indian nationality may be of ethnic differences. Some may be a mixture of Hindu, Muslim, Sikh, or Isai (Christian), which are predominant religious communities in India.
Eight articles studied the IPD as an anthropometric parameter in determining the width of the maxillary anterior, of which only seven articles were studied because in one study correlation coefficient was not mentioned. The population groups included in the studies were Kurdish, Aryans, Mongoloids, Indians, Caucasians, Brazilian, and Saudi. When the CIW was correlated with IPD, only Caucasians showed weak to moderate correlation (r = 0.13).13 When maxillary anterior teeth width was correlated with IPD, the Indian population showed highest correlation with IPD, mainly Indian males (r = 0.809) followed by Indian females (r = 0.726),7 the reason may be due to the male physique dominance over the females irrespective of the age group, and least correlation was found in Caucasian population (r = 0.15),13 whereas weak and negative correlation was found in Aryans (r = –0.38) and Mongolids (r = –0.439).5
Eight articles studied the intercomissural distance as an anthropometric parameter in determining the width of the maxillary anteriors. The population groups included in the studies were Aryans, Mongoloids, Indians, Caucasians, Brazilian, Saudi, Arab, and Serbians. When the CIW was correlated with ICOW, only Caucasians showed weak to moderate correlation (r = 0.08).13 When maxillary anterior teeth width was correlated with ICOW, Mulatto (r = 0.518) and blacks (r = 0.516) showed the highest correlation with ICOW,23 whereas Caucasians (r = 0.16) showed least correlation,13 and Aryans (r = –0.337) and Mongoloids (r = –0/316) showed negative correlation.5
Three articles studied the BW as an anthropometric parameter in determining the width of the maxillary anteriors. The population groups included in the studies were Indians and British. When the CIW was correlated with BW, only British White showed low correlation (r = 0.29).2 When maxillary anterior teeth width was correlated with BW, Indian males showed the moderate correlation with BW (r = 0.50) followed by Indian females (r = 0.447).7
One article each studied the PMN, COS, MAL, and width as an anthropometric parameter in determining the width of the maxillary anteriors. When CIW was correlated with MAL in Caucasians, it showed weak to moderate correlation on both right (r = 0.36) and left (r = 0.36) sides of maxillary arch, whereas combined width of maxillary anteriors showed moderate correlation on Caucasians’ right side of arch (r = 0.38), and weak correlation on Caucasians’ left side of arch (r = 0.36).13 Similarly, weak to moderate correlation was shown in Caucasians between CIW and MAW (r = 0.29) and the combined width of maxillary anteriors and MAW (r = 0.41).13 Both COS in Indian population (r = 0.17)20 and PMN in Turkish population (r = 0.28)17 revealed a very weak correlation with the maxillary anterior teeth width. However, in male population the circumference of head showed a positive correlation with the width of maxillary anterior teeth (r = 0.55) (Tables 1 to 4).
To some extent, the variations between the measurements in different studies may be attributed to the differences in measuring techniques, in the ethnicities of the populations studied, number of samples studied, gender-based variations, and various limitations, such as inaccuracies common to the making of the dental casts and minor positional differences that can occur during photography that may have affected the measurements. The available evidence shows that one particular anthropometric measurement cannot be used to determine the width of maxillary anteriors across various populations. Hence, more studies with large sample size and different population groups need to be conducted. Future studies should involve a broad clinical research program that would include the same analysis for an edentulous population, and then define a mathematical relationship of such structures.
Table 1
Determination of width of maxillary anterior teeth using COS
Table 2
Determination of width of maxillary anterior teeth using PMNs
Table 3
Determination of width of maxillary anterior teeth using MAL
Table 4
Determination of width of maxillary anterior teeth using MAW
CONCLUSION
Within the limitations of this systematic review, the following conclusions can be drawn:
The anthropometric measurement used depends on the population group in which it is being used.
There is no single anthropometric measurement that can be used to determine the width of maxillary anterior teeth.
In Indian population, high degree of correlation was seen between IAD, IPD, BW, and width of maxillary anterior teeth. The results of the previous study should be validated by including a large population size spread over the entire Indian subcontinent. This would also help to generate multiplication factor for various anthropological measurements for use limited to the Indian population.
In Saudi population, ICD has a high degree of correlation to the width of maxillary anterior teeth.
In Brazilian (mulatto and blacks) population, a high degree of correlation was seen between ICOW and width of maxillary anterior teeth.