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| ORIGINAL ARTICLE |
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| Ahead of print publication |
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Analysis of width/length ratio in maxillary anterior teeth among Gujarati young individuals: A cross-sectional study
Bhagyashree Hareshbhai Dave1, Shruti P Mehta2, Shreyansh Pragneshbhai Sutaria3, Priyanka Vaibhav Sutariya2
1 Department of Prosthodontics and Crown and Bridge, Siddhpur Dental College and Hospital, North Gujarat University, Ahmedabad, Gujarat, India
2 Department of Prosthodontics and Crown and Bridge, College of Dental Sciences and Research Centre, Gujarat University, Ahmedabad, Gujarat, India
3 Department of Oral medicine and Radiology, Gujarat University, Ahmedabad, Gujarat, India
| Date of Submission | 04-Oct-2022 |
| Date of Acceptance | 10-Dec-2022 |
| Date of Web Publication | 03-Mar-2023 |
Correspondence Address:
Bhagyashree Hareshbhai Dave,
Department of Prosthodontics and Crown and Bridge, Siddhpur Dental College and Hospital, North Gujarat University, Ahmedabad, Gujarat
India
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/aihb.aihb_186_22
Introduction: Correcting tooth size discrepancies are essential in achieving good dental and facial aesthetic in restorative and prosthetic dentistry. Hence, dental biometrics will be the most important key for an aesthetic restoration. This study aimed to analyse the width, length and width/length ratio related to the clinical crown of maxillary central incisors, lateral incisors and canines in adult Gujarati individuals. This study also aimed to check whether a correlation exists between the optimal tooth dimension guidelines for planning aesthetic restorations and natural tooth dimensions. Materials and Methods: Type III dental plaster casts were made from irreversible hydrocolloid impressions of 68 healthy adult participants. These casts were used to measure maxillary central incisors, lateral incisors and canines' maximum mesiodistal width and crown-root length with a digital vernier calliper (0.01 mm). The width/length ratio for each and every tooth was calculated. Results: The sample used in the study was 61.76% female and 38.24% male, with an age range of 18–30 years. 8.53 mm was the mean width value for the central incisors, lateral incisors 6.88 mm and canines 7.64 mm. The mean length was 9.80 mm for the central incisors, 8.25 mm for the lateral incisors and 9.29 mm for the canines. The average width/length ratio was 87% for the central incisors and 84% for the laterals and 83% for canines. Conclusion: The data received from the population studied are similar to previous research studies having similar methodology. However, great discrepancies in the absolute values were found when compared with other studies related to ideal tooth dimension guidelines on the aesthetic perception of dentists and personal preferences. The perception of what is considered natural seems to differ from what is considered aesthetically perfect.
Keywords: Dental aesthetic, maxillary anterior teeth, width/length ratio
How to cite this URL:
Dave BH, Mehta SP, Sutaria SP, Sutariya PV. Analysis of width/length ratio in maxillary anterior teeth among Gujarati young individuals: A cross-sectional study. Adv Hum Biol [Epub ahead of print] [cited 2023 Mar 31]. Available from: https://www.aihbonline.com/preprintarticle.asp?id=371228 |
| Introduction | |  |
The necessity for an aesthetic smile has increased in recent years. A beautiful yet confident smile has an excellent impact on the psychosocial well-being of people.[1] Dental treatment related to aesthetics should aim to provide both natural and pleasant appearance, especially in the field of prosthodontics.[2] Patients feel dissatisfied with their smile if the anterior teeth region shows spacing.[3] However, the patient's perception of dentofacial aesthetics does not necessarily match the dentist's perception, which highlights the importance of establishing an aesthetic diagnosis before treatment.[4] Hence, dental biometrics is a key aspect to consider for aesthetic restorations.[5],[6] The proportion of each individual tooth within the maxillary anterior teeth region is the percentage obtained by its width/length ratio.[7]
Aesthetic dentistry deals with correcting tooth size discrepancies in length, width and sometimes both.[8] However, the definition of ideal tooth dimensions remains challenging due to individual variations.[7] The relative dimensions of teeth seem to be among the most objective dental criteria within the aesthetic checklist because they can be easily and physically controlled.[9],[10]
Several guidelines have confused many clinicians when one must select the most appropriate size and shape of the tooth and determine their relation. However, current interest in aesthetics for restorative treatment has led to the publishing of different guideline figures. Many methods have been used to determine the maxillary anterior teeth size.[10] To facilitate the aesthetic restoration of a smile, many authors have tried to establish a set figure for this proportion.[7]
Due to individual variations and proximal/incisal tooth wear, the definition of ideal tooth dimensions remains difficult. To provide 'magic numbers' for the clinician, the 'golden proportion' and the 'golden percentage' have been proposed for classic elements of art and architecture.[9]
Lombardi was the first to mention golden numbers for anterior teeth, stating that strict application of the golden proportion has proved too rigid for dentistry. Measurements by Preston also confirmed that the golden rule is unrealistic in nature in this specific context.[9]
Sterrett et al.[11] in 1999 studied 71 individuals and obtained a mean value for the maxillary anterior teeth of 81% and a mean value for maxillary central incisors of 85% for the width/length ratio of the clinical crowns of the maxillary anterior teeth using diagnostic casts.[11] At the University of Geneva in 2003, a similar study showed an average width/length ratio for the clinical crowns in the three types of maxillary teeth of approximately 75% where the measurements from photographs of extracted teeth were obtained.[9] In 2007, Chu and Chu[12],[13] concluded that to enable the clinician to perform aesthetic surgical and restorative dentistry with predictability, an innovative aesthetic measurement gauge was used. They showed the set the width/length ratio at 78%. Gerard J. Chiche et al., in 1994, reported that the ideal width/length ratio should be between 75% and 80% for the central incisor.[14] Rosenstiel et al.[15] in 2009 found that the majority chose smile proportions that resulted in central incisors closer to 75% and 78% width/length ratios.
In 1973, Lombardi[16] was the first to suggest applying the golden proportion to dentistry. He also described using a 'repeated ratio' in the maxillary anterior teeth for better aesthetics. After that, in 1978, Levin[17] agreed that the golden proportion (62%) was the most appropriate tooth-to-tooth ratio when seeing from the front. However, the majority of beautiful smiles did not agree with the golden proportion formula, conflicting with the previous reports.[15] Ward[17] recommended using other tooth-to-tooth ratios, such as 70% for normal-length teeth, 62% for very long teeth and 80% for very short teeth. He surveyed several North American dentists about their aesthetic preferences for smiles with different proportions.
This study aimed to obtain dimensional data of the clinical crowns of the maxillary central incisors, lateral incisors and canines of an adult population with respect to width, length and width/length ratios and to determine whether a correlation exists between natural tooth dimensions and the guidelines of ideal tooth dimensions for treatment planning.
| Materials and Methods | | |
Demographics
This study was carried out in our institution from December 2021 to March 2022. All the research protocol details were reviewed and approved by the institutional review board in November 2021 (IRB/NTC.2021/0934). The study was carried out according to the Declaration of Helsinki version 2008. The sample size in this study consisted of 68 healthy Gujarati participants that met the inclusion criteria, which included adults with all six intact maxillary anterior teeth present without restorations and with well-defined anatomic elements. Impressions were made on these patients, and diagnostic casts were obtained. Exclusion criteria were as follows: participants below 18 years, pathological signs such as gingival alteration, hyperplasia, inflammation, altered passive eruption, gingival recession, history of periodontal surgery or history of alteration of the incisal or proximal surfaces of the tooth, and those with restorations, traumatisms, attrition, occlusal adjustment, dental malformation, malposition or diastema or previous orthodontic treatment.
Procedure
Maxillary impressions were made with irreversible hydrocolloid material (Zhermack Tropicalgin Zhermack SpA, Via Bova Zecchino, Badia Polesine [RO], Italy.) and type III dental plaster (Kalabhai Dental Pvt Ltd., Mumbai, India) was poured to obtain the diagnostic casts. These diagnostic casts were used for measurements. An extra-fine end digital calliper (Zhart Digital Caliper) was used to obtain the measurements, with a precision of 0.01 mm. The previously calibrated and trained examiner measured and recorded them in millimetres. The maximum mesiodistal width (perpendicular to the long axis of the tooth) and the maximum crown-root length (between the most apical point of the gingival margin and the most incisal point of the anatomic crown) of the maxillary central incisors, lateral incisors and canines were recorded for each tooth, and the scores were tabulated. The age and sex of each participant were also recorded.
Statistical analysis
The descriptive statistical analysis was done with software (SPSS statistics version 22.0; IBM Corp.; U.S.). The descriptive data obtained in this study were compared with data reported by other authors in similar studies.
| Results | | |
The sample was 61.76% female and 38.24% male, with an age range of 18–30 years. The mean, standard deviation (SD) and range of the width for each tooth individually and within its type of tooth are listed in [Table 1]. The mean width value was 8.53 mm for the central incisors, 6.88 mm for the lateral incisors and 7.64 mm for the canines. | Table 1: Mean (mm), range (min and max) and standard deviations of width for each tooth individually and within its type of tooth
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The mean, SD and range of the length for each tooth individually and within its type of tooth are listed in [Table 2]. The mean length was 9.80 mm for the central incisors, 8.25 mm for the lateral incisors and 9.29 mm for the canines. | Table 2: Mean (mm), range (min and max) and standard deviations of length for each tooth individually and within its type of tooth
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The mean, SD and range of the width/length for each tooth individually and within its type of tooth are listed in [Table 3]. The average width/length ratio was 87% for the central incisors and 84% for the laterals and 83% for canines. | Table 3: Mean (mm), range (min and max) and standard deviations of width/length ratio for each tooth individually and within its type of tooth
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[Table 4] lists the mean, SD and range of width, length and width/length ratio for each tooth and sex. When the mean width and length values for the three tooth groups were compared between sexes, the mean coronal width and length measurements were found to be significantly greater in men than in women. | Table 4: Data distributed by sex: Mean (mm) and standard deviations of width, length and width/length ratio for each tooth individually
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The ratio of the lateral width to the central width was 1.23:1. [Table 5] compares the average values obtained in this study with those obtained by other authors in similar studies.
| Discussion | | |
The sample for this study included 68 participants, which is near the sample size of similar studies. Almost all of these studies refer to statistically significant results. The measurements were made on cast models following the method used by other authors.[11],[18],[19],[20]
For dental measuring studies mentioned in other articles, the error linked to using the direct technique was similar or equal to other acceptable errors.[21] The data from other articles established the following ranking for maxillary crown width and length for the population studied: Centrals >canines >laterals. The most identifiable variations in the mean values of length were found in studies that measured extracted teeth,[9] which is, from the incisal edge to the cementoenamel junction rather than the gingival margin, leading to greater length values, and therefore, smaller ratios (width/length ratio of 78% for central incisors). Magne et al.[22] and Marcuschamer et al.[9] noticed that the measurements from the other studies were approximately 1 mm shorter than their own studies measuring anatomic crowns and not clinical crowns. That's why the resulting teeth appear excessively long if this ratio is applied clinically. However, these data may be useful in patients exposed to the cementoenamel junction and crown-lengthening techniques are applied.
The results of this study can be compared with those of other studies using the same measuring method.[23] Different data were found with a width/length ratio of 89% for central incisors by Hasanreisoglu et al.[20] The maxillary anterior teeth of the Gujarati population sample displayed a less square-like shape because the teeth may be longer in height and/or lesser in width than those of other Turkish populations. The width/length ratio for each tooth has clinical relevance, which usually remains stable, knowing it allows a calculation of the lost length from the existing width. The results show an average ratio of 87% for maxillary central incisors, 84% for laterals and 83% for canines. These findings disagree with other reports that suggest ideal tooth dimension guidelines based on dentists' preferences and aesthetic perception and are in agreement with the results of other studies;[21],[23] these seem to prefer central incisors that were closer to the 75%–78% width/length ratios.[12],[15],[24] The present results agree with the proportion thought of as ideal for maxillary laterals and canines. The study by Cooper et al.[25] in 2012, where smiles with central incisors with a ratio width/length of 82% were considered the most attractive, similar to the obtained width/length ratio for the central incisors in the study (87%). However, it exceeds the ideal ratio for central incisors, according to other authors who focus their studies on the harmonically aesthetic perception of different examiners and not on actual tooth measurements. Rosenstiel et al.[15] and Ward et al.[24] found that the majority chose smile proportions that resulted in central incisors with closer to 75%–78% width/length ratios for the dentists' preferred maxillary anterior tooth proportions from a frontal view. The disagreement seems to exist between the values more frequently when observing what is considered ideal and natural. Definite differences exist between the aesthetic perceptions of patients, technicians and dentists, and there is a lack of unanimity within each group, particularly in the patient group.
All of the above studies suggest width/length ratios for each individual tooth that differ from the author Levin's Golden proportion of 62%.[17]
The results indicate that women have lesser width and length measurements than men (P < 001), in accordance with most of the existing literature, which suggests that maxillary anterior teeth in women are between approximately 0.5 mm and 1 mm shorter. However, gender differences do not appear concerning the width/length ratio. These findings are supported by other studies[12],[18],[20] wherein the maxillary canines show the most significant gender-based morphologic variations compared with other teeth. A strong positive correlation was found between the left and right maxillary central incisors. A weak correlation was found in the length of the maxillary lateral incisors. Chu[12] also said that the normal range of asymmetry for the human body is there, an asymmetry of approximately 0.5 mm difference between the measurements of the right and left side and considered normal.
The ratio of the width of the lateral incisor/central incisor was also recorded by measuring directly on the casts, thus showing the real tooth width in this study. The results of the lateral incisor being 80% of the width of the central incisor, a ratio of 1.23:1 and match the other authors who carried out similar studies.[12],[18],[21],[22] However, the studies that use photographs as a tool to calculate the ratio have disadvantage as it provides the portion of the tooth that is visible from the frontal aspect, and so obtaining width lateral incisor/width central incisor values of 67%. Once again, there is no correlation between these proportions and the golden proportion that shows the ratio between centrals and laterals as 62%, a ratio of 1.62:1. When the golden proportion is used, the lateral incisors and canines appear narrow.
| Conclusion | | |
This study is designed for the clinical crown of the three anterior maxillary tooth groups from the Gujarati population sample (maxillary central incisors, lateral incisors and canines) for width, length and width/length ratios. Within the constraints of the present study, the following conclusions were drawn:
- Lateral incisors had narrow crowns (6.88 mm), followed by canines (7.64 mm) and central incisors (8.53 mm). Lateral incisors also had the shortest crowns (8.25 mm), followed by canines (9.29 mm) and central incisors (9.80 mm). The average width/length ratio was 87% for central incisors, 84% for laterals and 83% for canines
- The average ratio between the width of the maxillary lateral incisors and the central was 1:1.23. In this study sample, the golden proportion was not found
- Gender should be taken into consideration when estimating tooth size. Definite differences were found with women having lesser values for length and width than men. The canine was the tooth affected most by gender differences
- When the left and right sides were analysed, lateral incisors were more asymmetrical than canines, which were more than central incisors
- Greater variations were found when comparing the other studies, which provide guidelines for ideal tooth dimensions based on dentists' liking and aesthetic perception. This information may be helpful in accordance with other clinical parameters for diagnosis and treatment planning to achieve aesthetically pleasing and natural-looking restorations
- More studies with more participants are needed to record the patients' perceptions of different dental proportions.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
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