This cross-sectional study determined the patients’ elastic colour preferences. The study was conducted between July and September 2018 in the Orthodontic clinic at King Saud University in Riyadh, Saudi Arabia, and different private and Governmental Orthodontic clinics. The study protocol was approved by the Institutional Review Board (E-18-3307), King Saud University, College of Medicine in Riyadh, Saudi Arabia. The procedures followed were in accordance with the Helsinki Declaration of 1975, as revised in 2000 [10]. The sample size calculation was done as α=0.05 and effect Size (ES)=0.25 with Power=0.90. The sample size thus calculated was 318.

Inclusion criteria: A total of 319 patients (231 females and 88 males), aged between 18-36 years and who had undergone upper and lower fixed orthodontic treatments with metal brackets for at least six months were included in the study.

Exclusion criteria: Participants who were less than 18 or more than 36 years, less than six months with metal brackets and who were unable to read and understand the questionnaire alone were excluded from the study.

The included participants were able to read, understand and fill the self-administered questionnaire. The informed consent was signed by all the participants prior to being taking part in the study. The data were obtained from the study participants using a self-administered questionnaire that was distributed to them after they were shown a colour guide (to determine the colour that they preferred). The questionnaire [Annexure-1] was used in a previous study [3] and contained questions about the patient’s age, gender, place where they were treated and their preferences for coloured or transparent ligatures, light or dark shades, and changing ligatures for specific occasions (e.g., Eid, wedding, birthday…. etc.,). It was given to the patients and the colour guide was shown to the participants; preferred colour/colours was recorded for each patient by researchers. The colours were then divided into transparent, less noticeable and colourful groups. The less noticeable group included white, silver and grey, and the colourful group included the more obvious colours: red, blue, green, black etc.

The data were analysed using IBM SPSS Statistics for Windows (version 25.0; IBM Corp., Armonk, NY, USA). The descriptive statistics were calculated, and Pearson’s chi-squared analysis was performed to determine the influence of age and gender effects on colour preferences. A p-value less than 0.05 were considered as statistically significant.

A total of 319 patients participated in this study (88 males and 231 females), and the age range was 18-36 years of age. Most of the participants were between 19 and 25 years old and were treated in the private sector. [Table/Fig-1] shows the sample characteristics, and [Table/Fig-2] shows the patients’ answers to the questionnaire regarding their elastic ligature preferences. Most participants felt excited about changing their elastic colours (44.5%), and they liked to change the colours at each visit (45.5%). Most participants did not like having multicoloured elastic ligatures inside their mouths (77.4%), and they stated that they did not bother changing the elastic colours before certain occasions (49.8%).

[Table/Fig-3,4] show the gender and age associations with patients’ elastic colour preferences. There were no statistically significant differences in the elastic ligature colour preferences between the genders (p-value 0.552), but there were statistically significant differences between the age groups (p-value <0.001). Most of the participants who were 18 years of age preferred colourful elastic ligatures (47.6%), while the participants in age group 19-25 years old preferred less noticeable colours (45%). Those patients who were in age group of 26-35 years old and older than 35 reported that they did not have elastic ligature colour preferences (14% and 22.2%, respectively). Although the subjects were given the option to select more than one preferred colour, no patient was found to choose more than one preferred colour. [Table/Fig-5,6] show the details of the elastic ligature colour preferences for each gender and each age group.

[Table/Fig-5]:

Distribution of elastic ligatures colour preferences between females and males.

[Table/Fig-6]:

Distribution of elastic ligatures colour preferences among different age groups.

Three hundred and nineteen patients were included in this study, with females making up 72.4% of the total sample. Similar gender distributions were reported in the studies by Elekdag-Turk S et al., (76%) and Tariq A et al., (76%) [1,3]. The majority of the present study participants preferred less noticeable elastic ligature colours (41.1%), followed by coloured elastic ligatures (28.5%), transparent elastic ligatures (21%), and no colour preference (9.4%). Elekdag-Turk S et al., found that 55% of their sample preferred coloured elastic ligatures [1], while Tariq A et al., reported that 72% preferred coloured elastic ligatures [3]. The explanation for these differences may lie in the methodologies. Elekdag-Turk S et al., divided the ligatures into less noticeable colours (transparent, white, pearl, and silver) and coloured ligatures [1], while Tariq A et al., divided the ligatures into coloured elastics (including white, pearl, and silver) and transparent [3]. In the current study, the elastics were divided into less noticeable, coloured, transparent, and any of the above.

There was no statistically significant difference between the colour preferences of the genders in the present study. These results were in agreement with Elekdag-Turk S et al., who reported no difference in colour preferences between genders [1]. However, they contradicted Tariq A et al., study, who found a statistically significant difference in colour preferences between genders [3]. These contradictory results may have been due to the differences in the methodologies, as mentioned earlier. Although Alexander’s study mentioned that females prefer red [8], which support Hurlbert AC and Ling Y idea of an evolutionary basis for colour preferences [9]. On the other hand, researchers at Princeton University suggested that biological and cultural factors can influence colour preferences, which can also explain the difference in the results [11].

There were statistically significant differences in the elastic ligature colour preferences between the different age groups (p-value <0.001). The younger participants (18 years of age) preferred colourful elastic ligatures (47.6%), while patients who were in age group 19-25 years old, preferred less noticeable colours (45%). The older age groups reported that they did not have preferred elastic ligature colours. These results were in agreement with the results from the study by Elekdag-Turk S et al., Lee WY et al., found that elders’ colour preferences differed from those younger [1,12]. The determinants for colour preference were chroma and lightness attributes for the elder and younger groups, respectively. Tariq A et al., reported no differences between the different ages in their sample [3]; this difference in the results might be because they were not able to detect any differences due to their small sample size (100 participants).

Regarding the distributed questionnaire, most of the patients (44.5%) reported that they felt excited about changing their elastic colours, while 49.8% reported that they did not like changing the colours before certain occasions. The results were in agreement with those of Tariq A et al., [3].

In this study, the patients’ most preferred elastic ligature colours were transparent, silver, blue, and grey. The preference for less noticeable colours may be associated with aesthetic concerns about the metal brackets and the desire to make them less visible [1]. One explanation for why the patients selected less noticeable colours over transparent elastics may be because they had been undergoing orthodontic treatment for at least six months, and they may have experienced the food and drink stains that are associated with transparent elastics [5].

To the best of our knowledge, this was the first study to assess the colour preferences among patients attending an orthodontic clinic in Saudi Arabia. Elastic modules are an integral part of fixed appliances. The availability of different colours is important to the patients and their compliance during treatment. Also, knowledge about most popular colours is important to the orthodontists when ordering their materials.

The limitation of the current study is that the sample size was small, and it was not including patients younger than 18 years of age.

Based on the results of this study, most patients undergoing orthodontic treatment with fixed appliances preferred less noticeable elastic colours. Age was found to affect patients’ elastic colour preference, younger patients preferred coloured elastics while older patients preferred less noticeable and transparent elastic ligatures. No differences in colour preference was found between genders. Future multicentric studies with larger sample sizes, including wider age ranges, are recommended with questions for further investigation, like whether they would like to change the colour on each visit, as it was same colour they want every time or different colour.