There is a lack of research on personality traits and even fewer studies on the effect of personality on the choice of dental treatment [5–10, 17, 18]. To the author’s best knowledge, no evidence-based study investigated the influence of personality on dental morphology; therefore, this research may contribute to improving dental esthetic planning and increasing the level of patient satisfaction after treatment.
Previous studies took into account the individual's temperament to determine dental morphology. Visagism suggests a correlation between choleric, bloody, melancholic, and phlegmatic temperaments to rectangular, triangular, oval, and square tooth shapes, respectively [7, 8]. Several studies usually consider temperament and personality as synonyms [7, 9, 17, 18, 19]. The misuse of these concepts observed in both clinical and scientific fields can lead to false promises; thus, it is important to highlight their difference to avoid trivialization. In summary, an individual's cognitive, affective, and physical characteristics determine personality, which is formed mainly during childhood and involves experiences and temperament. Conversely, temperament observed in men and animals is physiologically determined [12–14, 20, 21].
Van der Geld et al. [22] investigated the relation between personality, smile attractiveness self-perception, and satisfaction in 122 participants by considering tooth size, color, position, visibility, upper lip position, and gums visibility (Dutch Personality Index questionnaire). This original study evaluated the influence of personality on dental morphology on 124 participants through the worldwide used (mainly in psychology) Enneagram Classification Test, which was chosen due to its popularity, simplicity, and ease of interpretation [12, 14, 15].
The intrinsic discomfort of humans towards self-criticism can bias self-assessment questionnaires used in this study; however, this potential limitation cannot be overcome [19]. The participants' dental morphology self-perception (CDM) was obtained by using images of the oval-, square-, and triangular-shaped maxillary teeth models without the influence of tooth size, color, and lip position; however, the association between personality and CDM was found not significant. Furthermore, there was no significant association between personality and the NDM of the participants determined through intraoral photographs evaluated by six calibrated dentists. Therefore, it cannot be stated that the personality type influences the esthetic perception of maxillary incisors shape and natural morphology.
Considering the CDM analysis, 104 (83.9%) and 20 (16.1%) participants chose only one tooth shape and a combination of two tooth shapes, respectively. These findings show that patients’ preferences must be consulted when planning esthetic dental treatments to meet individual expectations regarding dental morphology.
The triangular shape was the most frequent (59%) dental morphology chosen by the participants, followed by oval (23%), and square shapes (5%). Conversely, the most observed tooth shape in the NDM analysis was oval (44%), followed by quadrangular (42%), and triangular (14%). Paranhos et al [23] also observed a higher prevalence of oval-shaped (47%) maxillary incisors in comparison to square (32%) and triangular shapes (21%). This prevalence trend was corroborated by Pedrosa et al [6] (oval 56%, square 30%, and triangular 14%) and Wolfart et al [24] (oval 39%, square 36%, and triangular 25%).
In addition to the influence of personality, this study investigated the effect of the smile attractiveness self-perception through CDM analysis. The participants were distributed into Satisfied and Dissatisfied groups in the function of their wish to change or not the shape of maxillary incisors. The significant association between CDM and NDM in the Satisfied group indicates that the participant’s choice matched their actual dental morphology. Conversely, the lack of significant association between CDM and NDM in the Dissatisfied group indicates that participants tended to choose a different dental morphology. Therefore in this study, the participants presented an esthetic self-perception consistent with their smile attractiveness self-perception. This finding corroborated by Mehl et al [25] and Sriphadungporn & Chamnannidiadha [26] evidences the need for patients’ participation to obtain satisfactory dental esthetic planning.