Revisiting the Maxillary Teeth in 384 Subjects Reveals A Deviation From the Classical Aesthetic Dimensions

Comparison of the width-to-height ratio in maxillary anterior teeth in different populations: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The width-to-height (W/H) ratio values of maxillary anterior teeth are parameters used in esthetic dentistry. However, a meta-analysis of studies evaluating these parameters in individuals from different countries, taking sex into account, is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to determine and compare the W/H ratio values seen in the maxillary anterior teeth of different populations.

MATERIAL AND METHODS

A systematic search was performed using the PubMed/Medline, Google Scholar, and Web of Science databases to identify English and non-English language articles reporting the golden ratio, golden percentage, tooth ratio, tooth size, W/H ratio, maxillary tooth width, maxillary tooth height, maxillary anterior tooth size, and dental esthetics. The titles, full text, and abstracts were scanned by 2 investigators independently to identify articles that fulfilled the inclusion criteria. Using a meta-analysis software program, data extracted from each selected study were statistically combined using the random-effects model, and the weighted mean differences were calculated.

RESULTS

The search protocol resulted in a total of 987 articles, but only 15 articles fulfilling the inclusion criteria were included in the meta-analysis. While the sample size varied between 50 and 412 in the 15 analyzed studies, a total of 2304 individuals from 12 countries were evaluated. As a result of the evaluation of the general W/H means of the maxillary anterior teeth, the largest teeth were seen in Korea and Pakistan, and the general mean W/H ratios of the central, lateral, and canine teeth showed no statistically significant difference between sexes (P>.05).

CONCLUSIONS

As a result of the meta-analyses of the W/H ratios of the maxillary central, lateral, and canine teeth, the differences between populations were found not to be statistically significant.

Analysis of recurrent esthetic dental proportion of natural maxillary anterior teeth: A systematic review

STATEMENT OF PROBLEM

The recurrent esthetic dental (RED) proportion has been a benchmark for the rehabilitation of the maxillary anterior teeth of North American patients. While it has been evaluated in other populations, the global application of RED proportions in the rehabilitation of maxillary anterior teeth is unclear.

PURPOSE

The purpose of this systematic review was to examine the existing evidence on dental proportion to evaluate the existence of RED proportions in the esthetic smile in different geographic regions.

MATERIAL AND METHODS

A systematic search was conducted by reviewing different databases. The focused question was "Does RED proportion exist in esthetically pleasing smiles in different populations around the world?" The search included articles with a combination of MeSH keywords based on dental proportion from January 2000 to July 2020. The titles and abstracts were identified by using a search protocol. Full text of the articles was independently evaluated. The systematic review was modified to summarize the relevant data. The general characteristics, outcomes, and quality of studies were reviewed and analyzed systematically.

RESULTS

Seventeen studies were selected from the reviewed articles. Three studies were conducted in Europe, 10 in South Asia, and 4 in Western Asia. Eleven studies found that the mean perceived ratio of anterior teeth was not constant when progressing distally. Five studies reported that the ratio was constant in a small percentage of their populations, and 1 suggested that the ratio was constant if it remains between 60% and 80%. The central-to-LI and Ca-to-LI proportion values were not constant. Overall, the Ca-to-LI proportion values were higher than the central-to-LI proportions.

CONCLUSIONS

RED proportions were not found in the successive widths of maxillary anterior teeth among the reviewed data from different geographic regions. RED proportions are not the only standard for restoring esthetic smiles worldwide, and anterior tooth proportions differ among populations based on their race and ethnicity.

Maxillary Anterior Teeth Dimensions and Relative Width Proportions: A Narrative Literature Review

Predictable results in the aesthetic treatment of anterior teeth can be obtained by resorting to the concept of dental aesthetics and, in particular, defining the ideal tooth dimensions and proportions to obtain a harmonious smile. Considering the great variety of articles dealing with the topic, and the lack of updated reviews, this narrative literature review aims to evaluate current knowledge on anterior teeth dimensions and to verify the existence and the potential applications of the anterior teeth proportioning theories (Golden Proportion, Golden Percentage, RED Proportion, and Golden Rectangle). PubMed, Embase, Cochrane Library, and Google Scholar databases were comprehensively searched using different keywords and term combinations. The research includes articles published up to June 2023, no time limits were set, and only articles in English were included. Inclusion criteria comprehended reviews, clinical studies, and in-vitro studies. A total of 66 articles were selected. Two main topics were identified: "Anterior teeth dimensions", "Golden Proportions, Golden Percentage, RED Proportions, and Golden Rectangle". As far as tooth dimensions are concerned, different width ranges are recognized for men and women and for different ethnic groups. Perfectly symmetric contralateral elements are found in low percentages of subjects. The correlation between dental dimensions and facial parameters is not always present, and it strongly depends on the sample's ethnicity and gender. Ideal tooth proportions were only partially identified.

Evaluation of the parameters related to the golden ratio in the teeth of individuals from different countries: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Golden proportion, golden percentage, and recurring esthetic dental (RED) proportion are parameters used in esthetic dentistry. However, a meta-analysis of studies evaluating these parameters in individuals from different countries is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to determine and compare the golden ratio, golden percentage, and RED ratio values as seen in the maxillary anterior teeth of individuals from different countries.

MATERIAL AND METHODS

A systematic search was performed using PubMed/Medline, Google Scholar, and Web of Science to identify English and non-English language articles reporting the golden proportion, golden percentage, and RED proportion. The titles, full text, and abstracts were scanned by 2 investigators independently to identify articles that fulfilled the inclusion criteria. Using a meta-analysis software program, data extracted from each selected study were statistically combined using the random-effects model. Weighted mean differences, 95% confidence intervals, and heterogeneity were calculated for each measurement.

RESULTS

The search protocol resulted in a total of 752 articles, but only 26 articles fulfilling the inclusion criteria were included in the meta-analysis. While the sample size varied between 46 and 384 in the 26 analyzed studies, a total of 3786 individuals from 12 countries were evaluated. No similarity was found using the esthetic parameters determined in the populations to which the meta-analysis was applied.

CONCLUSIONS

Mathematical formulas did not provide consistent results that would allow for their use as a standardized guide for creating natural looking smiles. Rather, dental esthetic ratios should be set based on the racial and ethnic character of a population.

Comparison of maxillary anterior mathematical proportions among 3 dental arch forms

STATEMENT OF PROBLEM

Race and sex differences in the mathematical proportions of maxillary anterior teeth have been evaluated. However, studies exploring the relationship between the mathematical proportion of maxillary anterior teeth and maxillary dental arch form are lacking.

PURPOSE

The purpose of this clinical study was to determine if a correlation exists between the mathematical proportions of maxillary anterior teeth and 3 dental arch forms.

MATERIAL AND METHODS

Three hundred young participants were recruited according to predefined criteria, and images and maxillary casts were obtained. The perceived width and length of the maxillary anterior teeth were measured on the images by using a software program, and mathematical proportions, including width ratios and width-to-length ratios, were calculated for each. The casts were used to categorize each specimen into tapered, ovoid, or square groups by using a specific classification method, and the width ratios and width-to-height ratios of the 3 dental arch forms were compared. Statistical analysis was performed by using analysis of variance (ANOVA) or the Kruskal-Wallis H test to compare the mathematical proportions of maxillary anterior teeth among the 3 dental arch forms (α=.05). The intraclass correlation coefficient (ICC) was used to test the reliability of the investigators.

RESULTS

Except for the width-to-length ratios of the central incisor, mathematical proportions were affected by the dental arch form. The perceived width ratios of the maxillary lateral incisor-to-central incisor gradually increased from the tapered arch to the ovoid arch and from the ovoid arch to the square arch, with mean ±standard deviation values of 0.71 ±0.04, 0.73 ±0.05, and 0.79 ±0.06, respectively. For the maxillary perceived width ratios of canine-to-lateral incisor, the ovoid arch had the maximum perceived width ratios (0.86 ±0.10), followed by the tapered (0.82 ±0.10) and square arches (0.77 ±0.11). The width-to-length ratios of the central incisor were not affected by the arch form (P=.075), and the width-to-length ratios of the lateral incisor increased as the arch form became flat, with respective values of 0.70 ±0.10, 0.74 ±0.10, and 0.76 ±0.10. For the width-to-length ratios of the canine, the ovoid arch had the maximum perceived width ratios (0.58 ±0.10), followed by the tapered (0.53 ±0.10) and square arches (0.52 ±0.10).

CONCLUSIONS

The mathematical proportions varied among the 3 dental arch forms, and the dental arch form should be considered during the prosthodontic design of maxillary anterior teeth.

Macrodontia and double teeth: a review and case series

Macrodontia is a dental anomaly pertaining to the increased size of a tooth or multiple teeth. Double teeth are dental abnormalities concerning tooth morphology and the term traditionally refers to geminated or fused teeth. These anomalies may manifest in both primary and permanent dentitions and usually become apparent in childhood. They may cause a variety of clinical sequelae, including orthodontic complications, such as crowding, ectopic eruption of adjacent teeth and periodontal concerns. Double teeth are also at a higher risk of developing caries. The aesthetic implications of these dental anomalies can affect the psychosocial development of a patient. This, together with the range of functional repercussions, can often need dental treatment to improve quality of life. The functional and aesthetic complexities that may arise in the affected patients can require endodontic, restorative, surgical and/or orthodontic input as part of the management strategy and execution. We present four clinical cases of paediatric patients where a range of management approaches were employed for both macrodontia and double teeth.

Assessment of Golden Proportion among Natural Maxillary Anterior Teeth of Global Population: A Systematic Review

The purpose of this systematic review was to analyze studies, identify the existence of golden proportion between the perceived widths of the maxillary anterior teeth among the different geographical populations, and evaluate the range of dental proportion that exists regionally. An electronic search was conducted using PubMed, Medline, EMBASE, Scopus, Science Direct, Web of Science, and the Cochrane Library. The focused question was, “Does golden proportion exist in natural, aesthetically pleasing smiles among different populations around the world?” The search conducted included studies from January 2000 to September 2020, identifying articles in English with the specific combination of MeSH and other related terms. The title search yielded eight hundred and ninety-eight articles, and seventy-five articles were selected for full-text analysis. However, only fifty-two full-text articles were included in the systematic review. The mean predicted dental ratios were either larger or smaller than the successive widths of maxillary natural anterior teeth. Golden proportions were not found consistently among anterior teeth in different populations observed in the systematic review. The golden proportion is still a useful tool for the reconstruction of lost or damaged anterior tooth widths; however, it is not the only standard for restoring esthetic smiles worldwide, and anterior tooth proportions differ among populations based on their geographic, ethnic, and racial background. Moreover, consideration should also be given to an individual’s dentofacial variations in restoring anterior teeth.

Analysis of Lower Facial Third and Dental Proportions to Predict Maxillary Anterior Teeth Width in the Pakistani Population

Obtaining the size of the maxillary anterior teeth when performing an esthetic smile rehabilitation can be a difficult task. Metrics based on dental proportions to assist in the process are required. This study aimed to evaluate the lower facial third proportions i.e., the interalar, interphiltral, and intercommisural distance with dental proportions in predicting maxillary anterior teeth width in Pakistani citizens. This analytical study was conducted on 230 participants. Front face and retracted smile photographs were captured for all the participants, followed by maxillary impression making. The cast was then converted to 3D models for analysis. The data were entered into SPSS-25. Descriptive statistics were carried out for frequency, mean, standard deviation, and percentage calculation of gender, teeth widths, horizontal mid facial proportions, and age of the participants. Independent t-test was applied for analysis of gender and arch side disparity. Regression analyses were performed to analyze the relationship between independent variables (gender, age, weight, and height) and dependent variables (horizontal facial proportion, dental proportion). A p-value of ≤0.05 was considered statistically significant. The interphiltral distance (IPLD) modified with Preston proportion (PRP) showed no significant difference with combined central incisor width, whereas a significant difference was found with golden proportion (GP), 70% recurrent esthetic dental (RED) proportion, and golden percentage (GM) modification. However, the interalar (IAD) and intercommisural distance (ICoD) modified with dental proportions showed a significant difference with maxillary anterior teeth width. The width of maxillary anterior teeth determined by plaster dental cast and 3D dental cast showed no significant difference. The ICoD, IAD, and IPLD could not be used to determine combined central incisor and intercanine width directly. The interphiltral distance modified with Preston proportion is a reliable method to predict combined central incisor width in the population studied. There was a significant difference in gender disparity when ICD, IAD, and IPLD were modified with dental proportions, except in the case of IPLD by the Preston proportion group. The golden proportion, 70% RED proportion, and golden percentage by lower facial third facial proportions are not reliable methods to predict maxillary anterior teeth width.

An Analysis of Maxillary Anterior Teeth Crown Width-Height Ratios: A Photographic, Three-Dimensional, and Standardized Plaster Model’s Study

Objective. To analyze the width and height ratios of maxillary anterior teeth at different crown levels through photographs, 3D, and plaster dental model techniques in a subset of the Pakistani population. Material and Methods. This clinical study consisted of 230 participants. The maxillary impression, standardized photographs, and models were constructed for crown width and height analysis. The SPSS version 25 was used for statistical analysis. Descriptive statistics were carried out for mean, standard deviation, and percentage calculation of teeth width and height, gender, and age of participants. Paired $t$ -test analysis was carried out to compare the dependent variables (teeth size, width, and height ratios) with independent variables (techniques applied, side disparity). A $p$ value of ≤ 0.05 was considered statistically significant. Results. The mean width and height of maxillary anterior teeth obtained through photographs, 3D, and plater models were statistically different. The 3D dental model analysis showed reliable and accurate results. The mean width and height ratio of teeth were different on both sides of the arch. There was a significant difference ( $p=0.001$ ) in crown width-height ratios at different crown levels. Conclusion. The width and height ratios in the studied population were different at various crown levels. The dimensions of teeth varied from the incisal to the cervical part of the crown. Hence, rather than relying on a single, fixed ratio of 78% to 80% suggested by researchers for anterior teeth, the clinician should adopt different crown width-height ratios to restore teeth with the optimum esthetic outcome.

Biometry of width between labial transitional line angles in anterior teeth: an observational study

PURPOSE

The maximum width between the mesial and distal labial transitional line angles, described as “esthetic width” herein, could significantly influence the visual perception of the teeth and smile. This study aimed to conduct biometric research on esthetic width and to explore whether regular distribution exists in the esthetic width of human teeth.

MATERIALS AND METHODS

A total of 4,264 maxillary and mandibular anterior teeth were measured using the Geomagic studio software program. The proportions of maxillary to mandibular homonymous teeth and proportions between the adjacent teeth were calculated. Bilateral symmetry and the correlation between the esthetic and mesiodistal widths were both accounted for during the measurement procedures.

RESULTS

The mean esthetic widths were 6.773 ± 0.518 mm and 4.329 ± 0.331 mm for maxillary and mandibular central incisors, respectively, 5.451 ± 0.487 mm and 5.008 ± 0.351 mm for maxillary and mandibular lateral incisors, respectively, and 3.340 ± 0.353 mm and 5.958 ± 0.415 mm for maxillary and mandibular canines, respectively. Except for the mandibular canines, no significant difference in esthetic width was found among homonymous teeth from the same jaw. A high linear correlation was found between the esthetic and mesiodistal widths of the same tooth, except for the maxillary canines. Esthetic width proportions among different tooth categories showed some regular patterns, which were similar to those of the mesiodistal width.

CONCLUSION

Esthetic width is regularly distributed among the teeth in the Chinese population. This could provide an important reference for anterior dental restorations and dimension recovery in esthetic reconstruction of anterior teeth.

Face Proportions, and Analysis of Maxillary Anterior Teeth and Facial Proportions in a Thai Population

Background:

Esthetics is the primary consideration for patients looking for prosthetic treatment. Determining the facial types of Thai populations is important because most studies conducted in Caucasian populations mention their facial types, and describe the gender comparisons, and GP of the teeth.

Objectives:

This study compared facial proportions, analyzed the maxillary anterior teeth proportions and determined the relationships between teeth with facial measurements using the Golden Proportion (GP) and Golden Standard (GS) in a Thai population.

Methods:

A total of 200 students (18-35 years) with well-aligned maxillary anterior teeth participated in this study. Face heights and widths were measured from the face using digital calipers and faces were classified as narrow, average, and broad. Teeth and face proportions were compared with GP and GS. One-way ANOVA was performed to compare maxillary anterior teeth proportions and facial proportions with different face types (α= 0.05). Pearson’s correlation was used (α= 0.05) to determine the correlation between facial proportion and teeth dimension among different facial types.

Results:

The findings showed 82.50% narrow face, 13.50% average, and 4% broad face among Thai subjects. No GP or GS was found in the face and anterior teeth, but teeth and face proportions other than GP and GS were found. No significant correlation was found between the Width of the Central Incisor (WCI) with interpupillary distance and alar width.

Conclusion:

In this study, the GP was not found in the facial and teeth proportion. The data obtained from this study may help to provide guidelines for prosthetic and orthodontic management and help to select the proper size and form of the maxillary anterior teeth to achieve proper esthetic outcomes in the Thai population.

Mathematical Tooth Proportions: A Systematic Review

PURPOSE

The aim of this systematic review was to evaluate and compare three commonly used proportions that include the golden proportion, golden percentage, and Recurring Esthetic Dental (RED) proportion to identify which of the mathematical formulas, if any, can be used to provide predictable and repeatable esthetic clinical outcomes.

METHODS

A comprehensive search of electronic databases that included EBSCO, ProQuest, SCOPUS, Science Direct, Wiley, Google Scholar and PubMed was conducted using the terms: "golden proportion," "golden percentage," and "Recurring Esthetic Dental (RED) proportions" alone or in concurrence with one or both ensuing terms: "tooth proportions" and "esthetic tooth proportions." In addition, the following journals were hand searched for relevant articles: Journal of Prosthodontics, Journal of Prosthetic Dentistry and Journal of Esthetic and Restorative Dentistry. Related citations were also considered.

RESULTS

Tooth proportions varied substantially in the natural dentition. No studies revealed findings that supported the use of one mathematical formula to predict esthetic success. The golden proportion is present between the central to lateral incisor in some cases, but rarely between the lateral incisor and the canine. When compared to the other proportions, the golden percentage provided better starting points for tooth shape and size, but only when values were adjusted to consider other factors such as ethnicity and/or facial proportions.

CONCLUSION

Mathematical formulas did not provide consistent results that would allow for their use as a standardized guide for esthetically pleasing smiles. Although the golden percentage may be a good starting point if the percentages are adjusted on a case-by-case basis, generalized esthetic ideals cannot be determined by a mathematical formula and are open to interpretation by both the clinician and the patient.

Evaluation of golden percentage in natural maxillary anterior teeth width: A systematic review

STATEMENT OF PROBLEM

The color and form of teeth are 2 of the 3 main determinants of success in an esthetic restoration; the third is dental proportion. A recent systematic review of the literature devoted to the evaluation of dental proportion is lacking.

PURPOSE

The purpose of this systematic review was to investigate the quality and outcome of studies into maxillary anterior tooth proportion and to determine whether dental proportion ratios based on different geographic regions are appropriate.

MATERIAL AND METHODS

An electronic search was conducted using PubMed, MEDLINE, Google Scholar, Embase, Scopus, Cochrane Library, Web of Science, and Science Direct databases. English-language articles reporting with the specific combination of medical subject heading (MeSH) key words were analyzed by 2 investigators. The titles, full text, and abstracts were scanned by investigators independently to identify articles that fulfilled the inclusion criteria. The general characteristics, outcomes, and quality of each study were reviewed and analyzed systematically.

RESULTS

The search plan resulted in a total of 73 articles until September 2020; of which, 16 articles fulfilling the inclusion criteria were selected. The geographic distribution of the selected article revealed 12 articles from Asia, 2 from Continental Europe, and 2 from the United Kingdom. Golden percentage values of 25%, 15%, and 10% for central, lateral incisor, and canine teeth were not found. The mean predicted dental percentage was either larger or smaller than the successive widths of maxillary natural anterior teeth.

CONCLUSIONS

The golden percentage could not be used to formulate a smile design. Rather, the dental ratios should be set on a racial and ethnic basis for a population.

Golden Standard and Golden Proportion of Maxillary Anterior Teeth Among Saudi Population in Makkah

Background

Maxillary anterior teeth are important in achieving optimum aesthetics, Different methods are used to calculate their dimension: as golden standard (GS) to measure Width/Height (W/H) of anterior teeth and Golden Proportion (GP) to measure their perceived widths. Researchers had reported on GS and GP in different populations.

Objectives

The aim of the present study is to evaluate the occurrence of GS and GP of maxillary anterior teeth among the Saudi population in Makkah.

Materials and Methods

A total of 384 participants (2304 teeth) were included in this study; photographs were taken by using a digital camera at a fixed distance and saved on a personal computer; the perceived mesio-distal widths and occluso-gingival heights of the maxillary anterior teeth were measured; GS was calculated from W/H of upper central incisors (W11/H11 and W21/H21); and GP was calculated from width of canines/laterals (W13/W12 and W23/W22) and laterals/centrals (W12/W11 and W22/W21). The normal range of GS was considered between 75% and 85%, whereas the normal range of GP was considered between 55% and 65%. Data were analyzed by using suitable statistical tests, and p-value ≤ 0.05 was considered statistically significant. Both GS and GP were compared in relation to gender, race, and shape of the face.

Results

There were 43% of GS ratios, 14% of GP of canines/laterals, and 34% of GP ratios of laterals/centrals that were within the normal range. There were no significant differences between GS of males and females (p=0.512) as well as among different races (0.137), whereas there were significant differences among different face shapes (p=0.001). For GP of canines/laterals, there were significant differences between males and females (p=0.000), different races (p=0.000), and different face shapes (p=0.001). For GP of laterals/centrals; there were no significant differences between males and females (p=0.216) whereas there were significant differences among different races (p=0.000) and different face shapes (p=0.007).

Conclusion

The GS was 85% among the Saudi population in Makkah and it was more prevalent than other golden measures. The GP was 77.5 for canines/laterals and 65.8 for laterals/centrals, and their frequencies were very low. Personal characteristics and dento-facial specifications should be considered to obtain maximum aesthetics.

Minimally Invasive Diastema Restoration with Prefabricated Sectional Veneers

This case report presents a new technique for sectional veneer fabrication and diastema restoration with a prefabricated composite veneer. For the purpose of diastema restoration, a prefabricated sectional veneer provides the same benefits of a traditional ceramic sectional veneer (highly esthetic restoration with no need for tooth preparation) but involves a less technically demanding and time-consuming clinical procedure and a less delicate restoration with a reduced risk of accidental breakage and post-bonding crack formation. The technique presented in this case report bridges the gap between a direct and indirect technique for diastema restoration and introduces a new treatment option to close anterior spacing with a highly esthetic sectional veneer in a predictable and timely manner.

Evaluation of the maxillary midline, curve of the upper lip, smile line and tooth shape: a prospective study of 140 Caucasian patients

Background

A number of reference patterns such as the interincisal line, curve of the upper lip, width of the smile or shape of the teeth have been studied in different populations. Determining the frequency of different smile aesthetic parameters in a European Caucasian population and exploring possible gender differences is important in order to obtain predictable treatment outcomes.

Methods

Photographs were obtained under resting and forced smiling conditions in 140 individuals (70 males and 70 females) with a mean age of 20.1 ± 4.3 years. Different variables were recorded, including the position of the maxillary interincisal midline in relation to the facial midline, the arc and width of the smile, and the shape of the teeth. The data were processed using the SPSS version 15.0 statistical package, with application of the chi-squared test and a confidence level of 95%. The statistical power was 80%, and the level of significance 5% (α = 0.05).

Results

A total of 94.3% of the sample presented a maxillary interincisal midline coinciding with the facial midline, and 80% had a consonant smile line. The curve of the upper lip was upwards in 47.1% of the cases, followed by a straight curve in 41.4%. Most of the subjects (84.3%) presented a medium smile line with tooth exposure to the second premolar (61.4%). There were no significant differences between males and females.

Conclusions

The integration of aesthetic criteria is needed in order to guarantee satisfactory and predictable dental treatment outcomes. There were no statistically significant differences between males and females. The maxillary interincisal midline coincided with the facial midline, with a consonant smile arc and a medium smile line, upward lip curve and oval tooth shape.

Natural upper anterior teeth display an increasing proportion in mesio-distal direction

Background

This study aimed to determine the esthetic proportion of six natural upper anterior teeth in northeastern Thai population as well as the level of esthetic satisfaction of distinct tooth proportions.

Material and Methods

Front-view photographs were taken from participants living in the Northeastern Thailand (n=140) of the 18-35 years of age. Computerized program was used for measuring the size of each tooth. All subjects also scored the satisfaction level of different photographs portraying 4 proportions of anterior teeth (golden proportion, 70% RED, 80% RED, and an increasing proportion).

Results

We found that proportion of lateral-to-central incisor and canine-to-lateral incisor were 0.72 and 0.80, respectively on both sides. The proportions increased in mesio-distal direction. Our reported ratios were statistically different (P<0.05) from the golden proportion, golden percentage, and 70% RED. However, the ratio of lateral-to-central incisor, but not the canine-to-lateral ratio, was significantly different (P<0.05) when compared to 80% RED. Esthetic satisfaction level of 4 tooth proportions among northeastern Thais was not statistically different (P=0.054).

Conclusions

An increasing proportion of upper anterior teeth in the northeastern Thai subpopulation was found. No difference of esthetic satisfaction of 4 different tooth proportions among Thai laypersons warrants further study.

Key words:Esthetic proportion, Natural upper anterior teeth, Golden proportion, Increasing proportion, Esthetic satisfaction.