An analysis of maxillary anterior teeth: Facial and dental proportions

Automated facial landmark measurement using machine learning: A feasibility study

STATEMENT OF PROBLEM

Information regarding facial landmark measurement using machine learning (ML) techniques in prosthodontics is lacking.

PURPOSE

The objective of this study was to evaluate and compare the reliability, validity, and accuracy of facial anthropological measurements using both manual and ML landmark detection techniques.

MATERIAL AND METHODS

Two-dimensional (2D) frontal full-face photographs of 50 men and 50 women were made. The interpupillary width (IPW), interlateral canthus width (LCW), intermedial canthus width (MCW), interalar width (IAW), and intercommissural width (ICW) were measured on 2D digital images using manual and ML methods. The automated measurements were recorded using a programming language (Python), and a convolutional neural network (CNN) model was trained to detect human facial landmarks. The obtained data from the manual and ML methods were analyzed using intraclass correlation coefficients (ICCs), the paired sample t test, Bland-Altman plots, and the Pearson correlation analysis (α=.05).

RESULTS

Intrarater and interrater reliability values were greater than 0.90, indicating excellent reliability. The mean difference between the manual and ML measurements of IPW, MCW, IAW, and ICW was 0.02 mm, while it was 0.01 mm for LCW. No statistically significant differences were found between the measurements obtained by the manual and ML methods (P>.05). Highly significant positive correlations (P<.001) were obtained between the results of the manual and ML methods: (r=0.996[IPW], r=0.977[LCW], r=0.944[MCW], r=0.965[IAW], and r=0.997[ICW]).

CONCLUSIONS

In the field of prosthodontics, the use of ML methods provides a reliable alternative to manual digital techniques for carrying out facial anthropometric measurements.

Correlation between different points on the face and the width of maxillary anterior teeth

Statement of problem

There is currently no consensus on the relationship between maxillary anterior teeth and different facial anthropometric measurements. Additionally, whether these relationships vary by age and sex remains unreported.

Purpose

This clinical study aimed to investigate the relationship between the intercanine distance (ICaD) and intercanthal distance (ICD), interpupillary distance (IPD), interalar width (IAW), and intercommissural width (ICW), and to compare whether these relationships differ between different age and sex populations.

Material and methods

Participants (n = 409) were enrolled according to the inclusion criteria, and their standardized digital images were taken to measure facial and oral segments through an image processing program. The differences between ICaD and four facial measurements and the sexual differences for all measurements were compared using the 1-sample t-test. The differences among different age groups for all measurements were compared using the one-way analysis of variance (ANOVA) test, and a least significant difference (LSD) test was used for multiple comparisons. The association between ICaD and the four facial measurements was evaluated using Pearson correlation analysis. The correlation between ICaD and four facial measurements was evaluated using linear regression. Differences in regression equations among the subgroups were evaluated through subgroup regression analysis and the significance test of the difference between the two regression coefficients. Tests of significance were two-sided, with alpha level of 0.05. The reliability of the results was evaluated by calculating intraclass correlation coefficients.

Results

The ICD, IPD, ICW, and IAW significantly differed from the ICaD in both sexes (P < 0.01). All measurements were significantly greater in men than in women (P < 0.01). The differences among the age groups were statistically significant for all measurements except IPD (P < 0.05). A significant positive correlation was found between all facial measurements (r = 0.258 [ICD], r = 0.334 [IPD], r = 0.389 [ICW], and r = 0.393 [IAW]) and the ICaD in both sexes. The highest correlation was found between ICW(r = 0.345) and ICAD in men and IAW (r = 0.285) and ICAD in women. Except for the 20-29 and 50-59 age groups, the mathematical equations of ICaD and facial anthropometric measurements differed among the other age groups and sexes.

Conclusions

ICD, IPD, ICW, and IAW cannot be directly used to determine ICaD in both sexes. Nevertheless, when observed from the frontal aspect, by the use of digital images, all facial measurements correlated to the intercanine distance, with a high probability. The mathematical formulae combined with facial anthropological measurements can help ensure the combined width of the six maxillary anterior teeth, but the effects of sex and age differences should be considered.

Smile aesthetics in Pakistani population: dentist preferences and perceptions of anterior teeth proportion and harmony

BACKGROUND

This study aimed to evaluate dentist perceptions of attractive smiles in the Pakistani population, considering different dental proportions.

METHODS

Maxillary casts and digital images were used to create symmetrical representations of anterior teeth. dentists' preferences for good and bad teeth proportions, width/height ratios, and various dental proportions (golden, recurring esthetic dental (RED), golden percentage, Preston, and local/observed) were assessed using one sample and paired t-test. The Chi-square test was used to determine the gender disparities and factors affecting smile attractiveness. A p-value of ≤ 0.05 was taken as significant.

RESULTS

The RED proportion emerged as the preferred choice for normal-sized teeth, with specialists and general dentists favoring it over the golden proportion. For tall teeth, the golden proportion was predominantly preferred. The golden percentage received limited preference for aesthetic smile construction.

CONCLUSIONS

The smiles created using the principles of RED proportion were opted as the most attractive by local dentists. Factors such as tooth arrangement, color, and midline were highlighted as essential considerations in aesthetic smile construction.

The influence of different tooth proportions obtained using digital smile design on the perception of smile esthetics

OBJECTIVE

The aim of this study is to examine the effect of designs using different esthetic dental proportions made with a digital smile design program on the esthetic perception of individuals of different ages, genders and educational statuses.

MATERIALS AND METHODS

Different smile designs were made on facial photos taken of a female and male model using a smile design program. Four different dental proportions (golden proportion [GPR], golden percentage [GPE]), Preston proportion [P] and recurring esthetic dental proportion [RED]) and two different tooth shapes (oval and square) were used. Images with 16 different smile designs were presented to 4th and 5th-year students of a faculty of dentistry, dentists, specialist dentists and laypersons for scoring.

RESULTS

The gender of the participants did not affect the scores given (p > 0.05), and participants over the age of 30 and lay people had higher scores (p < 0.05). The GPR design was scored lower than RED when all designs were subdivided by tooth shape and gender (p < 0.001).

CONCLUSIONS

The esthetic perceptions of people of different ages and dentistry education levels may differ from each other. Using the GPR when designing a digital smile may not be suitable for both genders.

CLINICAL SIGNIFICANCE

If esthetic dental proportions are to be utilized when designing a smile, it may be more appropriate to use the P and RED proportions instead of the GPR. In addition, if the patients whose smiles will be designed are young and have received dental education, it should be considered that their esthetic expectations may be high. Trial registration ClinicalTrials.gov Identifier: NCT0567043.

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.

Customized planning of the visible maxillary arch width in harmony with interparopia width and smile width for female facial aesthetics

BACKGROUND

The visible maxillary arch width (VAW) is an important aesthetic-determining feature. To date, there is no well-established methodology to determine the aesthetically optimal VAW in customized treatment planning.

METHODS

In this study, the common traits of the dentofacial configuration were investigated in most attractive Asian and Caucasian female smiles. The smiling photo of a subject was digitally modified based on combined variations of VAW, smile width (SW), transverse facial dimensions (TFD), and vertical facial dimensions. These modified photos were assessed for aesthetics. The aesthetically essential parameters were identified, and their mathematic correlations and reference ranges were determined for different vertical facial patterns. Using the obtained results, a mathematic guidance was constructed for customized smile designing. The applicability of this guidance was tested in Asian females.

RESULTS

The most attractive Asian and Caucasian female smiles have intraracial and interracial commonalities in the VAW-to-TFD ratios. The interparopia width (IPD) predominated over facial widths in determining well-matched VAW and SW. For optimal smile aesthetics, the VAW and SW were correlated as simulated by the formula 1.92 IPD ≤ VAW + 2.3 SW ≤ 2.17 IPD, plus the VAW-to-IPD ratio within 0.54 to 0.62 and the SW-to-IPD ratio within 0.61 to 0.71, ranges tailored to vertical facial patterns. This constitutes a mathematic guidance for customized planning of the aesthetically optimal VAW. This guidance was preliminarily validated to be applicable to Asian females.

CONCLUSIONS

The VAW-to-TFD ratios were essential for Caucasian and Asian female smile aesthetics. The mathematic guidance could serve as a reference for customized smile designs for Asian females.

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.

Correlation Between Maxillary Anterior Teeth and Common Facial Measurements

Background

The symmetry between maxillary anterior teeth and the face holds significant importance. This study assessed and analyzed the relationship between facial parameters and anterior teeth in the maxillary arch of male and female subjects. Specifically, individual width and combined width (CW) measurements of the maxillary anterior teeth were investigated.

Methods

This study involved a total of 150 dentate Yemeni subjects (74 men and 76 women), whose ages ranged from 18 years old to 30 years old. A maxillary cast was created, and two digital photographs of the face of each subject were taken and analyzed. Digital calipers and AutoCAD were used to gather measurement data of the dental parameters (intercanthal distance [ICD], interpupillary distance [IPD], interalar width [IAW], intercommissural width [ICW], and bizygomatic width [BZW]) and facial parameters (profile distance).

Results

Significant correlations were found for the following: IPD and width of six maxillary anterior teeth of each of the study subjects; ICD and their central incisors; and BZW and their canine width measurements. In contrast, IAW and ICW were not correlated with all tooth measurements. Linear regression findings showed that the CW measurement of the four incisors was significantly correlated with all facial parameter measurements, excluding the ICW and IAW in females and the IAW, ICW, and profile distance in males.

Conclusion

The IPD and ICD of males and females may be used to determine their CW measurements. The BZW and IPD of males can be used to take precise anthropological measurements of the width of the central canines and incisors. Meanwhile, the IPD distance of females can be used to assess the central and lateral incisor widths.

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.

Two-dimensional facial measurements for anterior tooth selection in complete denture treatment

Purpose

Anterior tooth selection is one of the most challenging parts in determining tooth dimensions and critical to the aesthetic aspect of the complete denture treatment. However, the methods for anterior tooth size selection using facial measurements are still controversial. This study aimed to investigate the relationship between dental measurements and facial measurements, and to establish the anterior tooth size prediction equation using facial dimensions in the Thai population for the complete denture treatment.

Materials & methods

One hundred and twenty-five Thai participants (53 men and 72 women) aged 18-35 years old with Angle class I occlusion, did not currently undergo orthodontic treatment, had normal alignment on the maxillary anterior teeth, no attrition, abrasion, proximal restoration or prosthesis were investigated. One frontal facial photograph and one dental photograph of each participant were made using an image analyzing program (ImageJ version 1.53b) to measure the six horizontal facial distances, five vertical facial distances and three dental distances as 2D facial and dental measurements. Pearson correlation and multiple linear regression analysis were performed.

Results

The difference of facial and dental measurements between men and women were statistically significant (P < .001). Interpupillary width, interlateral canthal width, intercommissural width and bizygomatic width were correlated to dental measurements in both sexes. Intermedial canthal width and lip thickness were correlated to dental measurements in women. Face length and lateral canthus to lower border of face were correlated to dental measurements in men. Prediction equations of each dental measurement were established using only horizontal facial dimension and using both horizontal and vertical facial dimensions.

Conclusions

Facial and dental dimensions are sex-dependent. Facial measurements can be applied in a regression equation to predict dental measurements. Adding vertical dimensions of facial measurements to the prediction equations of anterior tooth size selection results in a higher R squared to 0.444. This finding can be used as a tool for anterior tooth size selection in the complete denture treatment.

The Evaluation of the Relationship Between Intercondylar and Intercanine Distances, Maxillary Central Incisor Width, and Various Facial Forms: A Comparative Study

Background The intercondylar distance is a predictable and invariable parameter, which is not influenced by the soft tissue limitations and resorption unlike comparable anatomical markers. Limited studies are available on the use of intercondylar distance for the selection of teeth arrangement and its relationship with varying face forms. Aim The study aimed to evaluate the relationship between intercondylar distance and maxillary intercanine tip distances and central incisor width in square, tapering, and ovoid facial forms. Materials and methods The comparative cross-sectional study was performed between January 2021 and August 2022. A convenience sampling strategy was used to include subjects between the ages of 18 and 40 years who had all of their natural teeth. The facial forms of the subjects were detected using a face form indicator and grouped into ovoid (group A), tapering (group B), and square (group C) forms comprising 63 subjects in each group. The intercondylar and intercanine distances and maxillary central incisor width were measured using a digital caliper. The Statistical Package for Social Sciences (SPSS) software (IBM SPSS Statistics, Armonk, NY) was employed to determine the statistical difference between and across the groups using one-way analysis of variance (ANOVA) and post hoc analysis, respectively. The correlation between the variables was determined by the Pearson correlation test. Results The average age of the subjects was 24.55±3.47 years, and the age distribution was found to be statistically insignificant between the groups (p=0.63). The study consisted of 21% of males and 79% of females. The mean intercondylar distance was 125.2 mm in ovoid, 123.1 mm in tapering, and 125.9 mm in square face forms (p<0.01). The mean intercanine distance was 34.82 mm for ovoid, 37.11 mm for tapering, and 37.04 mm for square facial forms (p<0.01). Similarly, the mean central incisor width was 9, 7.84, and 8.51 mm for ovoid, tapering, and square facial forms, respectively (p<0.01). The ratio of intercondylar and intercanine distances in ovoid, tapering, and square faces was 1:3.59, 1:3.31, and 1:3.39, respectively. The ratio of intercondylar and central incisor width was 1:13.9, 1:15.7, and 1:14.7 for the groups A, B, and C, respectively. There was a statistically significant negative correlation between square and ovoid incisor width, square intercanine and ovoid incisor width, tapering incisor width and intercondylar distance, tapering intercanine and intercondylar distances, and tapering incisor width and square intercanine distance. The relationship between intercondylar and intercanine distances and the central incisor width was also revealed to be statistically highly significant (p<0.01). Conclusion When face form is taken into account, tapering face form shows more positive result for the relationship of intercondylar distance with intercanine distance and central incisor width. In patients with edentulous conditions, the intercondylar distance may offer useful measurements for tooth selection.

Awareness of Golden Proportion in Tooth Forms Among Dental Scholars in Saudi Arabia: A Cross-Sectional Study

Background There are numerous uses of golden proportion (GoP) in dentistry, particularly cosmetic dentistry. The research on GoP has been lacking, particularly the knowledge of GoP among dentistry students still enrolled in classes and those undergoing training. Therefore, this study primarily aimed to determine how knowledgeable dental scholars (dentist scholars are final-year undergraduates, interns, Ph.D. scholars, and postgraduate students) in Saudi Arabia were of GoP in tooth forms. Methodology A total of 500 scholars who met the requisite criteria were considered eligible for this study and were provided with a questionnaire that consisted of background questions and 16 close-ended questions related to GoP. The data was analyzed, and descriptive and inferential statistics were used, with a P-value ≤ 0.05 at a 95% confidence interval (CI) deemed statistically significant. Results It was observed that most respondents believed that a smile was important for a patient. The results also indicated that most respondents had heard of GoP for smile designing, indicating that it is a well-known concept among dental scholars in Saudi Arabia. The findings also revealed that most respondents believed that the GoP ratio is 1.618 and that it is important as a guide to anterior restoration. Conclusions Most respondents considered the smile important and the golden ratio to be present in many fields, but their understanding of the concept varied. However, the study had some limitations, including the potential bias in self-reported responses and a lack of clinical application of the GoP. Future studies could investigate the practical implications of GoP in aesthetic dentistry and the effect of demographic factors on awareness and understanding of the concept.

Sexual Dimorphism in Teeth Dimension and Arch Perimeter of Individuals of Four Ethnic Groups of Northeastern India

Objectives There is a disparity between males and females when it comes to size and appearance. In forensic and anthropological investigations, it is crucial to identify an unknown individual's gender, and it is possible to discern individual differences based on differences in dental features among populations. For identifying individuals, tooth dimensions are an effective, simple, and low-cost means of determining sex. Based on dental casts, this study aims to assess sexual dimorphism among four ethnic tribes of Northeast India using the mesiodistal (MD) dimension of canines and arch perimeter (AP) of the upper and lower jaws. Methods In each of the four ethnic groups studied, 50 males and 50 females with dental casts were measured in millimetres for the MD dimension of canines and AP of the upper and lower jaws. SPSS version 20 (IBM Corp., Armonk, NY) was used to analyze the data based on Student's t-test, considering a p-value of <0.05 as significant. Results Males had significantly larger MD dimensions of canines in the maxillary and mandibular jaws (p-value<0.05). The AP of both maxilla and mandible are higher in males than females in all four ethnic groups. However, the difference between the two genders for the AP of the maxilla is statistically significant only in Meitei and Singpho groups (p-value<0.05). In the case of the mandibular jaw, the AP was significantly lower in females in all four ethnic groups (p-value<0.05). Conclusion Significant sexual dimorphism exists among the individuals in the four ethnic group populations. The MD dimension and AP are essential to establish sexual dimorphism among populations. The MD dimension of the maxillary and mandibular canine and AP showed significant sexual dimorphism in the present study among all four ethnic groups.

Golden Mean and Proportion in Dental Esthetics after Orthodontic Treatments: An In Vivo Study

PURPOSE

The definition of the golden ratio was established around the sixth century BC; Levin and Snow developed specific theories applicable in dentistry, which apply the golden proportion rule with the intention of reproducing a perfect smile. This study analyzed the literature and assessed whether these concepts remain valid and applicable in clinical practice, evaluating the theories with a group of patients followed by an experienced orthodontic team.

METHODS

This study was retrospectively performed on 400 patients (241 females and 159 males) who underwent orthodontic treatments. The analysis was conducted on intraoral frontal photos, both pre-treatment and post-orthodontic treatment, to observe if there was a statistically significant difference in the tooth display according to the golden mean and golden proportion theories.

RESULTS

The canine at the end of the orthodontic treatment had a greater visibility than that proposed by Levin and Snow.

CONCLUSIONS

This study revealed how these theories could be considered in certain respects, but nowadays are not totally valid and applicable to the clinical reality. Snow's theory appears to be more consistent with the clinical findings than Levin's theory.

Analysis of the Anterior Maxillary Zone: Evaluation of Chu’s Gauge Proportion Instrument in a Transylvanian Population

Background: The esthetic proportion gauge developed by Chu is using a 78% recurring esthetic dental (RED) proportion and it is based on evaluating the size and proportion of frontal teeth chairside.

The aim of the present study was to evaluate the validity of Chu’s device and to measure the correlation between the width and length of the frontal teeth, attempting to identify the application of the proportion gauge in Mureș county.

Materials and methods: From the 142 selected patients, 73 fulfilled the inclusion criteria. The height and width values of the participants’ teeth were measured with a digital caliper and evaluated with Chu’s esthetic proportion gauge. The measurements were then compared statistically.

Results: The values obtained from the digital caliper measurements did not correlate with Chu’s proportion scale, and the results showed no significant differences between the two sides (p >0.05).

Conclusions: In conclusion, the measured teeth ratios did not show a similarity with the predetermined esthetic proportion scale suggested by Chu.

Variability and Patterning in Permanent Tooth Dimensions among Four Ethnic Groups from the North-eastern States of India

Methods

The study was a comparative cross-sectional study among four different ethnic groups of North-east India among the age group of 20-30 years. Dimensions of the maxillary and mandibular teeth were measured with a digital Vernier calliper using the dental casts of 50 male and 50 female subjects from each of the four ethnic groups under study. The data were statistically analyzed using a Student's t-test and one-way analysis of variance. Statistical significance was set at p < 0.05.

Results

The tooth dimensions of all four ethnic groups were significantly lower than the standard values except for the MD dimension of the maxillary second molars of the Singpho group (9.13 mm vs. 9.0 mm); mandibular central incisors of the Meitei group (5.01 mm vs. 5.0 mm); and mandibular lateral incisors of the Meitei, Ao, and Singpho groups (>standard value of 5.5 mm) and BL dimension of the mandibular first premolars of the Meitei and Ao groups (>standard value of 7.5 mm); mandibular second premolars of the Meitei and Singpho groups (>standard value of 8.0 mm); and mandibular second molars of the Ao group (10.04 mm vs. 10.0 mm). In some instances, the comparative analysis revealed group variations in different tooth dimensions among the four ethnic groups (p < 0.05).

Conclusion

Variations were observed in the tooth dimensions among the four ethnic groups and within the same population. Unlike other parts of India, the North-eastern population belongs to a distinct ethnic race of indigenous people of East Asia, Southeast Asia, and the Arctic region of North America. Hence, population-specific data for India's North-eastern region are necessary for forensic odontology, dental anthropology, routine dental practice, and effective treatment planning.

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.

Comparison Between Human Maxillary Anterior Teeth and Commercial Acrylic Teeth: A Sex-Stratified Analysis

Objective:

The aim of this study was 1.To compare the total width of human anterior teeth from different races (White, black, and Asian) to the total width of commercially available anterior teeth molds and, 2. To compare the width and length of human central incisors (#9) from different races (White, black, and Asian) with those of commercially available central incisors (#9).

Materials and Methods:

The study consisted of 360 participants, with 60 females and 60 males in each of 3 racial groups: White, Black, and Asian. Metric measurements of natural teeth were obtained from dental casts, and those of acrylic teeth were obtained from company catalogs.

Statistical Analysis:

Data normality was determined by Kolmogorov-Smirnov and Shapiro-Wilk tests. The Kruskal-Wallis and Dwass-Steel-Critchlow-Fligner post hoc tests were used to compare measurements across the racial groups and commercial acrylic teeth. P value of ≤ 0.05 was set as statistically significant.

Results:

The results showed significant intra- and intergroup differences between males and females and across the 3 racial groups, especially among the Black group. Significant differences were also detected between artificial and natural teeth dimensions.

Conclusion:

Although similarities exist, generally, the dimensions of commercially available artificial teeth are different than that of natural teeth in the studied populations. Overall, in both males and females, the median length of natural tooth #9 is always smaller when compared to commercially available teeth. In contrast, in both males and females, the median width of natural tooth #9 is always larger when compared to commercially available teeth, except for female Asian population. Overall, significant racial differences exist in the length, width, and total width of natural teeth compared to commercially available teeth in the Black population. However, both the white and asian population showed less significant differences when comparing the length, width, and total width of natural teeth to commercially available teeth.

Analysis of the effect magnitude of different parameters on smile attractiveness

OBJECTIVE

To evaluate the effect magnitude of different parameters on smile attractiveness.

MATERIALS AND METHODS

A reference and 13 images were produced by manipulating 13 parameters. Image rating was performed with a 4-point Likert scale from least attractive (1) to most attractive (4). Image raters included laypeople, dental students, dentists, and dental specialists. Friedman and Wilcoxon image were used for estimate of effect size. Parameters were classified into small (0.10- < 0.30), medium (0.30- < 0.5), or large (≥0.50).

RESULTS

A total of 1040 people participated with good consistency (α = 0.861), and moderate reliability (0.64-0.7). The reference image had the highest rank (laypeople:11.79, dental background: 12.55). For effect size; gingival margin level (-0.11, -0.01), teeth width proportion (-0.09, -0.10), inverted smile arch (-0.09, -0.21), commissure line cant (-0.15, -0.17) and low smile (-0.24, -0.23) had small effect size; occlusal plane cant (-0.36, -0.49), midline cant (-0.36, -0.48), and midline shift (-0.37, -0.49) had medium effect size; diastema (-0.55, -0.54) and color (-0.56, -0.56) had large effect size for the laypeople and dental groups. High smile (-0.42, -0.51), incisor edge symmetry (-0.46, -0.54) had medium effect size in laypeople group and large effect size in the dental group. Width to length tooth proportion (-0.26, -0.39) had small effect size in the laypeople group and medium effect size in the dental group.

CONCLUSIONS

Smile parameters had different effect magnitude on smile attractiveness and were classified into small, medium, or large parameters. Neither laypeople nor professionals have a collective judgment on what constitutes a beautiful smile.

CLINICAL SIGNIFICANCE

This study investigated the effect magnitudes of 13 smile parameters and presented a small, medium, and large smile parameters classification. It should provide the clinician with an insight into the expected effect each parameter has on the smile.

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.

Analysis of the esthetic preferences of Spanish laypersons and dentists regarding the different width proportions of the maxillary anterior teeth

STATEMENT OF PROBLEM

Multiple esthetic width proportions have been described for maxillary anterior teeth. However, the esthetic characteristics of each have not been compared simultaneously to determine which proportion is preferred by dentists and laypersons.

PURPOSE

The purpose of this study was to evaluate the preferences of dentists and laypersons with respect to internationally recognized dental esthetic proportions. It also sought to determine whether a relationship existed among dentists' preferences as per their specialty and among laypersons as per their academic field.

MATERIAL AND METHODS

Two smile images, one male and one female, were digitally modified to meet the golden proportion and the recurring esthetic dental (70%) and golden percentage. The 2 resulting sets of images (original images and digitally altered ones) were presented to dentists and laypersons through a Web-based survey site. The Pearson chi-squared and Fisher tests were used to assess the differences in the esthetic preferences among the groups (α=.05).

RESULTS

A total of 363 answers were obtained from dentists and 750 from laypersons. Both groups considered recurring esthetic dental to be the most esthetic proportion and golden proportion to be the least esthetic proportion. The dentists' preferences as per their specialty followed the same trend, whereas the laypersons' preferences were more scattered according to their academic field. The recurring esthetic dental proportion was preferred in images of both sexes, golden proportion smiles were the least preferred for female smiles, and golden percentage was the least preferred for male smiles.

CONCLUSIONS

The results obtained indicated that the preferred esthetic proportion both for dentists and laypersons was the recurring esthetic dental 70%, with the dentists' specialty or laypersons branch of knowledge not affecting choice.

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.

Evaluation of Dental Golden Ratio in Terms of Facial Esthetics

Aim and Objectives:

This cross-sectional study examined the Bolton index of 6 maxillary anterior teeth and the facial esthetic ratios in the Turkish population with healthy facial appearance.

Materials and Methods:

Face photographs of the subjects, taken using a DSLR camera, were fixed in the Frankfort horizontal plane. The measurements were made on the images using ImageJ 1.52a software and certain ratios of face and teeth were calculated such as Bolton index (BI). Differences between genders were evaluated and comparisons with golden ratio of 1.618 were conducted on SPSS.

Results:

Males had significantly higher upper, middle, lower, and total facial height compared to females ( P < .001, P = 0.0257, P = .0243, P < .001, respectively). Right to left distance of labial commissure (LC)/distance from the distal edge of right canine to the distal edge of left canine ratio had golden proportion. Ratio of naso-menton length to facial width showed golden ratio only in males. The ratio of the width of upper middle incisor to the width of canine tooth also showed golden ratio in both genders.

Conclusions:

The present study presents noteworthy data about facial and teeth ratios of the young adult Turkish population that will guide plastic surgeons and orthodontists in clinical practice.

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.

Analysis of dental esthetic proportions in a Spanish population sample

PURPOSE

The present study aimed to analyze in a Spanish population sample the compliance of the anterior maxillary teeth to the dental esthetic proportions described in the literature.

METHODS

Photographs of the smiles of 78 individuals were calibrated and digitally analyzed considering the following proportions: golden proportion (GP), recurring esthetic dental (RED), golden percentage (GPG), Preston's proportion and Modified golden percentage (MGPG). For statistical analysis, the t-test of an independent sample was applied, and compliance percentages for each standard were recorded.

RESULTS

The existence of RED 70% or 80% has not been registered. The percentages of compliance with GP were within a range between 0% and 16%. The mean tooth width ratios were adjusted to the values described by Preston (P > 0.05), but the compliance percentages were low (3.33-25%). GPG only presented high percentages of compliance in the lateral incisors (53.33-62.5%). MGPG showed the highest percentages of compliance (50-68%).

CONCLUSION

After analyzing a Spanish population sample using smile photographs for the first time, GP, RED, GPG and Preston's proportion standards are not fulfilled and therefore, not suitable for treatments that seek a smile that reproduces natural principles. However, the values designated by MGPG with a deviation of ±1% are largely applicable for treatments that aim for a natural smile.

Maxillary anterior teeth dimension and relative width proportion in a Saudi subpopulation

Objectives

Achieving a natural smile while restoring anterior teeth is challenging. Selecting appropriate dimensions of teeth is important for aesthetics. This study aims to measure and analyse the dimensions of the maxillary anterior teeth and their relative width proportions in a Saudi subpopulation.

Methods

One hundred and eighty patients (112 men and 68 women) with intact maxillary anterior teeth (age range = 20–30 years) participated in this research. Maxillary impressions (Vinyl Polysiloxane) were created and poured. A digital caliper was used to record the length and width of maxillary anterior teeth in millimetres (mm) from the dental casts, and the casts were digitally photographed to calculate relative width ratios.

Results

The mean width for central incisor was 8.74 mm (men = 8.89 mm, women = 8.60 mm), lateral incisor 6.64 mm (men = 6.79 mm, women = 6.49 mm) and canine 7.82 mm (men = 8.01 mm women = 7.63 mm). The recorded mean lengths for these teeth were 9.84 mm (men = 10.04 mm, women = 9.64 mm), 8.09 mm (men = 8.30 mm, women = 7.89 mm) and 9.08 mm (men = 9.48 mm, women = 8.69 mm). The mean values of apparent width/width ratio measured on the cast photographs were 63.69 mm for the lateral incisor/central incisor and 78.35 mm for canine/lateral incisor. No statistically significant difference was found between the mean values of the apparent width/width ratio of the right and left sides and between men and women.

Conclusions

This study showed a minor asymmetry between left and right side anterior teeth among the participants. The width to length ratio of the central and lateral incisors was similar for both genders, with minor differences in the canines. A squarish form of anterior teeth for the Saudi population with dimensional similarities to the Turkish population was found.

The Effect of Perioral Scan and Artificial Skin Markers on the Accuracy of Virtual Dentofacial Integration: Stereophotogrammetry Versus Smartphone Three-Dimensional Face-Scanning

This study evaluated the effects of different matching methods on the accuracy of dentofacial integration in stereophotogrammetry and smartphone face-scanning systems. The integration was done (N = 30) with different matching areas (n = 10), including teeth image only (TO), perioral area without markers (PN) and with markers (PM). The positional accuracy of the integrated models was assessed by measuring the midline linear deviations and incisal line canting between the experimental groups and laser scanner-based reference standards. Kruskal–Wallis and Mann–Whitney U tests were used for statistical analyses (α = 0.05). The PM method exhibited the smallest linear deviations in both systems; while the highest deviations were found in the TO in stereophotogrammetry; and in PN in smartphone. For the incisal line canting; the canting degree was the lowest in the PM method; followed by that in the TO and the PN in both systems. Although stereophotogrammetry generally exhibited higher accuracy than the smartphone; the two systems demonstrated no significant difference when the perioral areas were used for matching. The use of perioral scans with markers enables accurate dentofacial image integration; however; cautions should be given on the accuracy of the perioral image obtained without the use of markers.

Association of the nasolabial angle and lip length with the gingival and interdental smile line-A gender based evaluation

OBJECTIVE

Proportionate existence of the lip framework and gingival scaffold have a critical role in smile esthetics. So, the present study was conducted to assess and correlate the nasolabial angle (NLA) and lip length (LL) with gingival smile line (GSL) and interdental smile line (ISL).

MATERIALS AND METHODS

One hundred and twenty periodontally healthy patients with an age group 20 to 40 years were equally divided based on gender into two groups. The parameters of NLA, LL, GSL, ISL, amount of midfacial gingiva, and interdental papilla display were recorded in the maxillary anterior sextant.

RESULTS

The mean values of NLA and LL at rest and on smiling were found to be higher in males. Majority of study population exhibited Low GSL (LGSL) and High ISL (HISL). On correlation of LL with GSL, the difference in the mean values between males and females for LGSL were highly significant, for HGSL and Cupid's bow the values were significant. The mean values of midfacial gingiva and interdental papilla visible in females was greater than males.

CONCLUSION

The NLA and LL influence the quantum of gingival exhibit in maxillary anterior teeth with a definitive sexual dimorphism and this can be considered a valuable reference point in smile designing procedures.

CLINICAL SIGNIFICANCE

The quantum of gingival exhibit on smiling is an important feature in periodontal, implant, restorative, and smile designing procedures in patients possessing HGSL and HISL category of GSL and ISL. It is indicated that the lip length is correlated with the amount of gingival tissue display both in midfacial as well as interdental region and which needs to be considered by the clinician.

Rehabilitation Challenge in Patient With a High Smile Line: Case Report and Review of Surgical Protocols

INTRODUCTION

Defects in the maxillary anterior teeth are delicate and difficult to solve because of the esthetic, functional, and psychological impairment that may arise if the rehabilitation treatment does not return the damaged tissues to the naturalness. Esthetic predictability and reduced surgical interventions are some great reasons to simplify dental treatments. During the presurgical evaluation, the clinician should review the implant esthetic risk profile, considering the patient's smile line, the esthetic demands, the hard and soft tissue thickness and width, and the gingival biotype. Thus, achieving long-term esthetic results initiates with a detailed case planning before surgical intervention.

CASE PRESENTATION

The present report described a complex esthetic clinical case involving teeth and dental implant related to a high smile line. The clinical case was solved through immediate implant placement and immediate loading using a personalized prosthetic abutment and finalized with the installation of metal-free prosthetic restorations.

CONCLUSION

The use of a personalized prosthetic abutment helped to achieve a better emergence of the prosthesis under the periodontal tissues. Although it was a challenging esthetic case, especially because of the high smile line, the result was a natural smile while the adjacent soft tissues maintained their esthetics and health.

An analysis of the aesthetic proportions of anterior maxillary teeth in a UK population

Introduction Many aesthetic proportions have been proposed for use in dentistry: Golden Proportion, Preston's Proportion, Recurrent Esthetic Dental (RED) Proportion and Golden Percentage. Although there have been studies to consider these proportions in other countries, there have been no studies in the UK to evaluate their prevalence and value.Methods The maxillary anterior teeth of 509 students from University of Birmingham's School of Dentistry were photographed in a standardised manner and the aesthetic proportions statistically analysed using an unpaired one-sample t-test.Results Golden Proportion existed in a very limited number of the sample. RED did not exist in the sample. The sample's average ratio was similar to Preston's Proportion; however, there was too wide a distribution for the proportion to be of relevant use. The vast majority of the sample conformed to modified Golden Percentage values; 22.5% for central incisors, 15% for lateral incisors and 12.5% for canines.Conclusion Golden Proportion, Preston's Proportion and RED Proportion have limited value in aesthetic dentistry as they do not accurately or broadly represent natural, aesthetic smiles. However, slightly modified Golden Percentage values are vastly more representative and are recommended as a more relevant geometric component to smile design principles in the UK.

Evaluation of influence factors on the width, length, and width to length ratio of the maxillary central incisor: A systematic review and meta-analysis

OBJECTIVES

The aim of this study was to analyze whether symmetry of left and right sides, gender, measuring method, and ethnicity have influences on width (W), length (L), and width to length ratio (W/L) of the maxillary central incisor (MCI) and provide a reference for dental treatment planning in the esthetic zone.

MATERIALS AND METHODS

An electronic search was conduct of the dental literature. Studies reporting data about measurements were included. Data were extracted and analyzed for the differences between left and right, male and female, different measuring methods, and ethnicities by Review Manager and Stata statistical software.

RESULTS

Seventeen studies were included. There were no differences between measurement of the left and right groups, perceived and actual measuring groups. However, differences were found between genders in MCI's W and L but no difference in W/L. Differences were also found between Asians and Caucasian subjects in MCI's W, L, and W/L.

CONCLUSIONS

The results of this meta-analysis suggest that symmetry of left and right sides and measuring method do not influence MCI dimension. Gender and ethnicity are found as influence factors for MCI dimension. We believe these findings can be helpful for dentists to decide and design the dimensions of the restorations for maxillary anterior teeth in clinical practices.

CLINICAL SIGNIFICANCE

In the process of designing maxillary anterior teeth for implantation, the contralateral MCI can be helpful to create a symmetrical esthetic restoration. For patients with maxillary anterior tooth loss or diastemas, dentists should divide the left and right space equally and keep the MCI contact area aligned with the midline. Dentists should take face size and gender into consideration when making treatment plans for the MCI. Facial parameters as well as the size ratios of the previous teeth can be evaluated and may influence the size and shape of the teeth. When measuring anterior teeth or facial dimensions for esthetic evaluation, the recommended method is to measure the perceived sizes of a facial view image created by a digital camera. Slight discrepancies may exist between the actual and measured values due to the curvature of the arch and the angle in which the photograph was taken.

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.

Anatomical factors associated with gender recognizability: A study on intraoral standardized photographs

AIM

The aim of this research was to evaluate the possibility of identifying the sex of 1 subject through visual assessment of a frontal photograph of dentition, and to investigate if some morphological characteristics are related to sex determination.

METHODS

5 expert dentists, 5 non-expert dentists and 5 laypeople were made to watch 100 intraoral photographs for 5 seconds each and to establish their sex. The responses of the participants and the baseline characteristics of photographed dentitions were analyzed.

RESULTS

The proportion of right answers was 56.0% ± 8.2% in the group of expert dentists, 65.0% ± 6.0% in the group of non-expert dentists and 58.6% ± 4.5% in the group of non-expert people. The round shape of maxillary central incisors was related to the female gender (P = .006). The male condition was correlated with poor oral hygiene for 4 observers. Female sex perception was correlated with round morphology of upper central incisors for 3 observers.

CONCLUSION

No difference in the ability to determine the sex was registered among groups, suggesting that sex perception is not strongly influenced by the characteristics of dentition.

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.

Golden proportion evaluation in maxillary anterior teeth amongst Saudi population in Riyadh

Introduction

In achieving pleasing dental aesthetics, the maxillary anterior teeth are essential. Numerous methods are used to measure their dimensions, including the golden proportion between their perceived widths and the width-to-height ratios, referred to as the golden proportion and is considered as a gold standard for esthetic evaluation.

The objective of this study was to evaluate the existence of the golden proportion between the width of the maxillary anterior teeth of Saudi males and females.

Methods

This clinical observational study included a total of 61 participants that met the inclusion criteria having 36 females and 25 males, all Saudi nationals, presented to Princess Nourah bint Abdulrahman University (PNU), College of dentistry, clinics. Dental casts of the maxillary arches for each participant were made after taking digital impressions in addition to taking photographs. The dimensions and the perceived width of the anterior teeth viewed from the front were measured using a digital caliper. SPSS was used to analyze the data.

Results

There were significant differences between the subject’s width-to-height ratios and the golden proportion of 0.80 where (p-value < 0.05). Thus, indicating that no golden ratio was observed except in case of tooth number 12 in male subjects where mean value was (0.83) with a standard deviation of (0.09) and the p-value of (p = 0.144) > 0.05.

Conclusions

From the perceived widths of maxillary anterior teeth, the golden proportion was not found to exist. No gold standard was detected for the width-to-height proportions of maxillary incisors. Therefore, in addition to anterior teeth measurements, specific population characteristics and perception of an agreeable smile should be considered for evaluating esthetics.

Relationship between different points on the face and the width of maxillary central teeth in a Turkish population

STATEMENT OF PROBLEM

Dentists may have difficulty determining the appropriate widths of the maxillary central incisors (CW) when restoring teeth for patients with edentulism. Anthropological measurements can help.

PURPOSE

The purpose of this observational study was to evaluate the relationship between different anthropological distances on the face and the CW in a young Turkish population.

MATERIAL AND METHODS

A total of 210 Turkish dental students without dental and facial deformities participated in this study. Two different digital photographs of their face (relaxed and smiling) were taken. The intercommissural width (ICW), intermedial canthus width (MCW), interlateral canthus width (LCW), interpupillary width (IPW), interalar width (IAW), and CW were measured. The t test, Pearson correlation analysis, and multiple linear regression analysis were performed to determine the relationship between facial measurements and CW (α=.05).

RESULTS

A significant correlation was found between facial measurements (r=0.516[ICW], r=-0.534[IAW], r=-0.639[MCW], r=-0.599[LCW], and r=-0.683[IPW]) and CW in both sexes. All facial measurements, except ICW and IPW in women and MCW in men, had a significant effect on CW according to the multiple linear regression analysis.

CONCLUSIONS

IAW and LCW can be used to determine CW in both sexes. The ICW and IPW can be specific anthropological measurements for men, and the MCW can be a specific anthropological measurement for women to determine CW.

Evaluation of "Golden Proportion" in Saudi individuals with natural smiles

Background

The Golden Proportion (GP) has been considered by many as the most harmonious recurrent tooth-to-tooth ratio and has long been proposed as an aesthetic guideline for restoring/replacing maxillary anterior teeth. Researchers investigated GP in various populations.

Purpose

The aim of the current study was to investigate the occurrence and prevalence of the GP between the perceived widths of maxillary anterior teeth in a Saudi population with natural smiles.

Materials and Methods

A total of 360 Saudi dental students (180 males and 180 females) with natural smiles and who met the inclusion criteria were included in the study. Frontal photographs were captured for all participants while maximally smiling using a digital camera with standardized settings. Photo-editing software was used to measure the perceived mesiodistal width of each anterior maxillary tooth in all digital images. Paired and student t-tests were performed to detect side and/or gender differences respectively. Calculated ratios of the perceived mesiodistal widths of the teeth were compared with their respective GP values using a one sample t-test. Statistical significance was set at 5%.

Results

For both genders, there were significant differences (P < 0.001) between the calculated ratios and the golden ratios. No side differences in the GP were detected. Males had wider teeth than females however significant differences between genders was detected for the centrals (P < 0.001) only.

Conclusions

Width ratios of the maxillary anterior teeth did not follow the GP for the examined Saudi population. Males had wider anterior teeth with the centrals exhibiting a significant gender-based difference. There was no side-dependent variation for both genders.

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

Dental esthetics need to be defined from the scientific perspective in order to obtain predictable treatment outcomes and avoid the effects of subjectivisms on the part of the dental profesional. It can be deduced that the ideal dimensions in the maxillary anterior sector are difficult to establish. Therefore, the primary purpose of this study was to define the dimensions of the maxillary anterior teeth and the relationships between them. In addition, an analysis was made to reinvestigate whether they complied with the Golden proportion, the RED (Recurrent Esthetic Dental) proportion and the Golden percentage. A total of 2304 tooth corresponding to 384 subjects were evaluated. The central incisor presented a mean width of 8.58 mm and a height of 9.35 mm, while the lateral incisor presented a width of 6.69 mm and a height of 7.75 mm. The mean width of the canine was 7.69 mm, with a height of 8.68 mm. The teeth revisited in this study did not comply with the ideal dimensions in the anterior maxillary sector as established by the Golden proportion, Golden percentage and RED. The information obtained from this study can be clinically applied to restore the dimensions during periodontal surgery, restorative dentistry and prosthetic rehabilitation.

An evaluation of the influence of teeth and the labial soft tissues on the perceived aesthetics of a smile

Objective The aim of this study was to investigate how the lips and teeth may affect the perceived aesthetics of a given smile. Lips and teeth were collectively assessed in different fields of view to see how they may contribute to smile aesthetics. The perception of 'beauty' was assessed to determine whether differences existed between; dentists, non-dentists, males and females.Methods Five subjects were photographed to produce the following views: 1) retracted anterior teeth; 2) lips at rest; 3) zoomed smile; and 4) smile showing the lower face. Images were compiled in a survey questionnaire and shown to respondents who ranked the subjects in order of aesthetic appeal. Kendall's coefficient of concordance (W) and median rank scores were used to determine the statistical significance.Results All groups demonstrated statistically significant agreement in the perception of beauty. Both the teeth and lips seemed to contribute similarly to the attractiveness of a smile. Dentists seemed to be more influenced by teeth in a zoomed smile view, however, this was negated when viewing a broader field of view. All other groups showed no difference in perception of aesthetics with changing field of view.Conclusion Both lips and teeth seem to contribute to the aesthetic appeal of a smile. Dentists may have a tendency to place a disproportionate weight to teeth when assessing a smile close up.

An investigation of the esthetic indicators of maxillary anterior teeth in young Turkish people

STATEMENT OF PROBLEM

Comprehensive studies evaluating the dimensions of anterior maxillary teeth in the Turkish population with respect to different esthetic parameters are lacking.

PURPOSE

The purpose of this clinical study was to evaluate different proportions of teeth and compare them with current esthetic parameters such as the golden proportion, recurring esthetic dental proportion, and width-to-height ratio of central incisors and to evaluate whether the apparent contact dimension of maxillary anterior teeth follows the "50:40:30" rule.

MATERIAL AND METHODS

A total of 150 Turkish dental students (81 men and 69 women) aged between 18 and 24 years participated in the study. Standardized digital photographs of the mouth were made from an anterior view. The width and length of the maxillary central incisor, apparent width of the maxillary lateral and canine teeth, and distances between contact areas of the maxillary incisor teeth were measured with software. Differences between the measured proportions and the determined esthetic parameters were assessed with the 1-sample t test (α=.05).

RESULTS

The width and length proportions of the maxillary incisor teeth in both sexes were significantly different than the golden and recurring esthetic dental proportions. The width-to-height ratio for the maxillary central incisor was different from 80%, which is considered optimal, and the difference among these parameters was statistically significant (P<.001). The apparent contact dimensions on the right and left sides were not statistically significantly different (P>.05). However, the proportions did not fit the 50:40:30 ratio that has been defined as the esthetic proportion, and the differences were statistically significant (P<.001).

CONCLUSION

Proportions among maxillary anterior teeth were found to be significantly different from the golden proportion and recurring esthetic dental proportion in both sexes. The proportions of apparent contact dimension were significantly different than the 50:40:30 ratio in both sexes. The width-to-height ratio for maxillary central incisor was significantly different from 80% in both sexes.

Evaluation of the role of skull anthropometry for complete denture teeth selection: A cross-sectional study

Background:

Success of complete denture treatment lies in the ability to make it indiscernible from the natural. The selection of the six maxillary anterior teeth is of utmost importance as it contributes most to denture esthetics. Although various techniques and methods to determine the width of maxillary anterior teeth and its relation to various body measurements were done, the simple technique of using circumference of head has been less documented, specifically for Indian population.

Aims and Objective:

The aim of this study was to determine whether a relationship exists between the widths of the upper six anterior teeth to head circumference and the objective was to decide whether head circumference can be used as a deciding criterion to select size of maxillary anterior teeth for Central Indian population.

Materials and Methods:

This study was done on 300 people who included 135 males and 165 females. The circumference of head (A) and the combined width of the six anterior maxillary teeth (B) were measured and the ratio of A: B was determined.

Results:

EPO Info software version 6 was used to derive the statistical analysis with unpaired Student's t-tests. In male students, the mean of the ratio between the head circumferences to the combined widths of the anterior maxillary teeth was 10.14:1. In female students, the mean of the ratio between the head circumferences to the widths of the anterior maxillary teeth was 10.09:1. The average circumference of head to mesiodistal width of six anterior teeth ratio was concluded to be 10.

Conclusion:

Within the limitations of this study, the results suggest that head circumference divided by 10 can be used to select a teeth set with the resulting value as the combined mesiodistal width of six anterior teeth. This can be used as a starting point for determining the width of the anterior maxillary teeth for edentulous patients, which can be further confirmed with the esthetic appearance and with other facial measurements.

Risk factors associated with open gingival embrasures after orthodontic treatment

OBJECTIVES

To investigate the incidence of and contributing factors to open gingival embrasures between the central incisors after orthodontic treatment.

MATERIALS AND METHODS

One hundred posttreatment patients (29 men and 71 women; mean age, 24.7 years) were divided retrospectively into occurrence and nonoccurrence groups based on intraoral photographs. Based on the severity, the occurrence group was further divided into mild, moderate, and severe groups. Parameters from periapical radiographs, superimposed lateral cephalograms, and study models were compared between the occurrence and the nonoccurrence groups by using independent t-tests and were also analyzed on the basis of severity via analysis of variance. Logistic regression analysis was performed to identify the contributing factors to open gingival embrasures.

RESULTS

The incidence of open gingival embrasures between the central incisors was 22% and 36% in the maxilla and the mandible, respectively. Lingual movement of the incisors, distance from the contact point to the alveolar crest after treatment, antero-posterior overlap of the two central incisors before treatment in the maxilla, and distance from the contact point to the alveolar crest after treatment in the mandible were significantly associated with the occurrence of open gingival embrasures ( P < .05). In the mandible, the amount of intrusion was significantly related to severity ( P < .05).

CONCLUSIONS

The incidence of open gingival embrasures following orthodontic tooth movement is high. Therefore, attention should be paid to the contributing factors to prevent or reduce the occurrence of open gingival embrasures.