L’évaluation des proportions dorées et rouges au sein d’une population Nord-Africaine

ABSTRACT

Healthy adult Muslims who practice Ramadan fasting (RF) follow strict religious rules regarding their lifestyle. RF influences several parameters, including nutrition, hydration, and sleep habits, and can potentially reduce physical performance. It seems that RF prevents athletes from training and participating in competitions, and prevents the general community from engaging in physical exercise. This places practicing Muslim athletes at a competitive disadvantage. Therefore, the goal of this guide was to provide practical recommendations, based on expert panel consensus, for healthy athletes and their support staff on how to adopt appropriate behavioral, social, and psychological strategies to cope with the changes and constraints resulting from RF. The recommendations developed in this guide are not limited to prescribing appropriate exercise during the month of Ramadan (ie; schedule, frequency, intensity, duration, type of exercise, and training load), but cover different aspects of lifestyle such as nutrition, hydration, and sleep, and address psychosocial and cognitive aspects related to RF. These recommendations are intended for healthy individuals. Patients with chronic illnesses should refer to their doctor to ensure an eventual safe practice.

introduction

The constant advancement in dental materials and technologies, with the increase of esthetic demands have led to the development of guidelines (1-3).

These tools are used to predict the teeth proportion and dimensions, especially for maxillary anterior teeth as they are the most involved in both dental and facial esthetics (2, 4 ).

Various geometrical and mathematical theories were suggested by researchers (5).

Golden proportion (GP) and Red proportion (RP) are the most known theories (6, 7) which could offer guidelines for the smile design (7).

The concept of GP was inspired by the theory which states that a relationship exists between nature and mathematics (7).

Leonardo da Vinci established a GP of 0.618:1 (62%) between body parts of and published drawings based on this (8).

Lombardi, in 1973, was the first who applied this theory in dentistry (7, 6).

Levin(6) suggested that, from the front, the apparent width of the maxillary lateral incisor presents about 1.618 of the apparent width of the maxillary central incisor.

However,the apparent width of the maxillary canine presents 0.618 of the apparent lateral incisor width.

The recurring esthetic dental proportion (RP), proposed by Ward, establish a constant width proportion between successive maxillary teeth viewed from the front progressing distally (6).

Many studies(2, 6-10) were conducted to check their validity amongst different populations reporting both their approval and disapproval.

A systematic review reported that, in natural smiles, the existence of the GP is a myth (1).

Among the North-African population, no previous data are available.

Thus, the present study aimed to assess the existence of both GP and RP amongst a sample of Tunisian population.

methods

Study design

The present study was conducted from August to November 2021 at the Fixed Prosthetic department of the dental clinic of Monastir, Tunisia

It was conducted according to the STROBE guidelines (11).

Sample size was calculated using following formula:

N= (Z score)2 *SD*(|1- SD|) / (error margin percentage)2

The confidence interval and error margin were respectively set to 95% and 6%.

The standard deviation of was equal to 0.92 according to Abdulaziz S. Alqahtani et al (5).

The sample size was calculated to 78.

Ethical clearances were obtained from the ethical committee of the faculty of dental medicine Monastir,Tunisia.

All Participants were clearly informed by the study protocol

Study population

During the elaboration of the study, all patients consulting the cited department above were included.

For each one, a careful intra oral examination was performed.

Following non -inclusion criteria were, then applied for the selection:

More than 40 years, presence of restored decayed or crowned anterior teeth, previous orthodontic treatment, interdental spacing or crowding and passive gingival eruption

Protocol and measurements

For each participant, an alginate (Algimajor – Major) impression was taken.

On casts, using a sharp-edged digital caliper (Mitutoyo, 500/196/30 AOS, AbsoluteCaliper (0e6), Illinois, USA), width (W) and length (L) of all anterior teeth were measured by a qualified subject(RK in the authors list) three times.

For the accuracy and calibration, the constant values were used.

The width (W) was measured between contact zones along a line perpendicular to the longitudinal axis of the tooth.

The height or length (L) was measured from the gingival zenith to the incisive edge for the incisors, and to the canine tip for the canines along the longitudinal axis ( Figure1).

To assess the incidence of the GP, width ratios for maxillary lateral to central incisors and lateral incisor to canine were calculated and, then, compared to the GP of 0.618 and 1.618 respectively.

Concerning the RP, the ratios were compared to each other’s.

Data analysis.

All data were collected, and then analyzed using SPSS software 21.

Data normality was checked through Kolmogorov Smirnov test.

Descriptive results including the mean (M), the maximum (MAX), the minimum (MIN) and standard deviation (SD) of both widths and lengths were calculated.

Matched sample t-tests were used to compare measurements between right and left sides.

Anova test was used to compare the measurement between three sites.

Independent sample t-tests were used to compare width and height between males and females.

To assess the incidence of the GP and RP, one sample t and independent t tests were respectively used.

The significance level was fixed at α = 0.05.

results

All results are summarized in tables 1-5. The main findings are:

A total of 100 participants were included in the study (97 females and 21 males) aged between 19 and 35 years.

- For anterior teeth widths and lengths, statistically not significant differences were observed between right and left sides except for the canine width (Table 1 ).

- The maxillary central incisors were the largest (8.60±0.58mm) and the longest (9.71±1.14mm).

The ratio was 0.89±0.09mm (Table 2)

- About teeth dimensions and ratios, statistically not significant differences were observed between males and females (Table3 )

- Calculated width ratios for lateral to central incisors and lateral incisor to canine differences significantly (P=0) from the GP (Table 4).

It means that the GP is not applicable among the studied population.

- Calculated width ratio of lateral incisor to central incisor with the width ratio of canine to lateral incisor differences significantly from each other (P=0) (Table 4 ).

It means that the RP is not applicable among the studied population.

discussion

The overall results showed that GP does not exist between maxillary anterior teeth as statistically differences were observed after the comparison between teeth width ratio and golden ratios.

The same conclusions are deduced for the RP after the comparison between ratio of teeth widths to each other’s.

Scope of the study

The restoration of maxillary anterior teeth is always considered as a challenging task and requires a deep analysis of the clinical situation.

A careful attention, should be attributed to their dimensions and proportion.

Suggested tools are useful to predict them through mathematical calculations directly or digitally by software’s of smile design ( 12 )

Both GP and RP were assessed in various populations ( 2 , 6-10 ).

No previous one was conducted in NorthAfrica.

Thus, the present study aimed to investigate their suitability among a Tunisian population.

Discussion of results

In the present study, the mean widths of maxillary anterior teeth were 8.6, 6.6 and 7.7 mm respectively for central incisor, lateral incisor and canine.

Mean lengths were 9.68, 7.8 and 8.62 mm for respectively central incisor, lateral incisor and canine.

Findings are close to those reported by previous studies among different populations (5, 13 - 16 ) (Table 5).

Minor variations could be attributed to the ethnic difference between populations.

The comparison of teeth widths between left and right sides showed statistically not significant differences for all anterior teeth except the canine width.

The same founding was reported by Chu et al (17) and Mavroskouvis and Ritchei (18)

However, Abdulaziz S et al (5) and Sanjay Kumar SAH et al (15) reported similar dimensions between left and right sides.

Besides, statistically not significant differences were observed between males and females for both width and height of maxillary anterior teeth.

Nevertheless, Alqahtani et al (5) found noticeable difference between the two gender only for length and reported significant differences only for canine.

Also, Sanjay Kumar SAH et al (15) reported statistically significant differences between the two genders.

The meta-analysis of Londono et al ( 1 ) showed that men exhibited greater canine to lateral width ratio than women.

The current study showed that GP was not applicable for maxillary anterior teeth.

Consequently, this relationship between seems to be not applied in the Tunisian population.

Finding reported by previous studies conducted among different populations are similar (6, 10 , 19 , 20 ,21- 24 ) ).

Researchers agreed that the use GP is theoretical ( 5 ).

In act, it was considered as a reliable tool to determine the width of the maxillary central incisors( 3 )

The adherence to a stuked proportion for all patients seems too impractical ( 25 ).

When designing smiles, ethnic and cultural differences should be taken into consideration ( 1 ).

Preferences are complex and generally supported by beliefs and relationships (1).

The GP seems to be strict and rigid to be applied in dentistry ( 6 )

That’s why, Ward proposed the RP which establish a constant width proportion between successive maxillary teeth offering the possibility to match teeth features with facial proportions ( 15 ).

The advantage that it is not stuck into 62% ratios like the GP.

It includes all ratios from 60 to 80% allowing more flexibility ( 5 ).

The present study reports also, that the RP seems to be invalid among the Tunisian population.

Many studies are in agreement with these founding among the Kerala( 24 ) Iranian( 6 ) and Bangladeshi( 19 ) populations.

Some authors suggested using facial measurements in order to perform natural teeth dimensions ( 26 ).

Although, previous studies are in agreement with the present one, it seems unsuitable to calculate the widths ratio and compare them together.

The RP should, thus, be assessed individually ( 6 ).

Discussion of the methodology

For this study, the sample size (n=100) appears to be acceptable comparing to other studies (6, 19 ).

It was slightly higher than size of a previous studies (10,21)

For the measurement protocol, it was preferred that measurements were taken by only one operator to avoid the inter-examiner variability.

For more accuracy, they were performed three times

To assess the RP, Shetty et al (9) have defined three categories of central incisors “" small”, “" medium”, and “" tall” and calculated ratios in each category.

This subdivision could provide more precise results.

Study limitations

The study limitations were relevant to the measurement protocol.

First, it would be more precise if the length has been measured from the cemento-enamel junction instead of the gingival margin ( 14 , 27 ).

Then, tooth width would be more precise if width were digitally measured on images ( 5 , 6 , 24 ).

Nevertheless, it is a first investigation amongst a North African population which could provide useful data regarding anterior teeth dimensions.

conclusion

Both GP and RP between widths of maxillary anterior teeth were not applicable among the Tunisian Population.

Their universal use could not be systematically applied.

when restoring patients’ smiles, dentists should update their esthetic concepts.

Whatever, the used concept, the appropriate communication with the patient is essential to ensure his satisfaction.