Layperson's preference of the transverse occlusal plane in asymmetric facial model

The impact of dental midline angulation towards the facial flow curve on the esthetics of an asymmetric face: Perspective of laypeople and orthodontists

PURPOSE

The objective of the present article was to evaluate the ımpact of dental midline angulation in asymmetrical faces.

MATERIALS AND METHODS

A full-portrait image was used to create a set of digitally modified images with a different degree of facial asymmetry, towards the right and the left side of the face respectively. Half of the images were designed with an equivalent angulation of the dental midline in respect to the curve of the lower third of the face and half of them without. Through a web survey, 250 laypeople and 250 orthodontists were asked to assess the attractiveness of each image separately.

RESULTS

As the asymmetry of the face was increased, facial attractiveness was further decreased both for laypersons and orthodontists. For each one of the modified images, when the dental midline was following the curve that was formed from the inclination of the simulated asymmetry of the face, the smile attractiveness scores were significantly higher compared to a straight dental midline.

CONCLUSION

Facial asymmetries derived from the inclination of the nose, the chin and the commissural line of the lips can significantly affect the smile attractiveness. An orientation of the dental midline towards the facial asymmetry in order to follow the facial curve, can be beneficial for the smile attractiveness compared to a perpendicular to the face dental midline. During the design of a smile, clinicians have to take into consideration deviations in facial midline, in order their restorations to be in harmony with the rest of the face.

CLINICAL SIGNIFICANCE

During the design of a smile, clinicians have to take into consideration deviations in the facial midline, in order their restorations to be in harmony with the rest of the face.

Perception of laypersons, orthodontists, and oral and maxillofacial surgeons about the transverse occlusal plane

INTRODUCTION

Transverse occlusal plane (TOP) should be parallel to the true horizontal lines of the face (ie, the interpupillary line [IP] and commissural line [CL]). This study aimed to investigate the opinions of laypersons, orthodontists, and oral and maxillofacial surgeons about the impact of imbalanced IP and CL on facial attractiveness.

METHODS

We used a symmetrical face image as the reference. Then, using Photoshop software, we constructed the following 6 photographs: TOP roll relative to CL and IP (3° and 6°) with parallelism of CL and IP, CL roll relative to TOP and IP (3° and 6°) with parallelism of TOP and IP, TOP and CL roll relative to IP (3° and 6°). Consequently, the participants rated the photographs on the basis of their attractiveness. Kruskal-Wallis and Mann-Whitney U tests were used to compare the ratings.

RESULTS

One hundred thirty-one laypersons, 22 orthodontists, and 20 surgeons participated in this study. It was found that 51.1% of laypersons, 86.4% of orthodontists, and 70% of surgeons selected the reference photograph as the most beautiful, followed by the photograph with a 3° roll of CL relative to TOP, with parallelism of TOP and IP (29% of laypersons, 31.8% of orthodontists, and 35% of surgeons).

CONCLUSIONS

Most participants selected the reference photograph as the most beautiful and realized a roll in the horizontal planes up to 3°. The parallelism of the esthetic line of dentition relative to interpupillary is preferred over its parallelism relative to CL.

Aesthetic Preference in the Transverse Orientation of the Occlusal Plane in Rehabilitation: Perspective of Laypeople and Dentists

The present study had a convenience sample with 236 laypeople and 242 dentists who completed an online questionnaire to choose the most attractive image among six pairs for comparison. Control image: symmetric (parallelism between occlusal plane (OP), commissural line (CL), and interpupillary line (IL)). Change of Control, obtaining three images with a 3-degree inclination of the labial commissures. Image A: OP parallel to IL; Image B: OP parallel to CL; Image C: OP at 1.5 degree mean angulation between IL and CL. Non-parametric comparison (IBM© SPSS Statistics vs. 27.0, p < 0.05). The "Dentists" group's decreasing order of preference (attractiveness) of the images is: Control > A > C > B (p < 0.05). In the "Lay" group, it is: Control > A > (C not ≠ B). Dentists significantly prefer more the Control and Image A than laypeople (p < 0.001). Sex (single exception in laypeople), age, and dentist's area of activity did not interfere in the perception of attractiveness. Dentists and laypeople preferred the Control when compared to images with CL canted. In the existence of CL inclination, the preference of the groups was the IL as a reference for OP orientation, with the mean angulation or coincident with the CL being considered less aesthetic.

The Law of Minimum Vertical Dimension: Evidence for Improvement of Dental Occlusion

The law of minimum vertical dimension (MVD) states that “when the mandible moves to reach the maximum intercuspal position, this always involves bringing the mandible and maxilla as close together as possible.” Therefore, after the first occlusal contact is made, the MIP will be reached through reduction of the vertical dimension. Our objective of this study, through an integrative review of the literature review, was to determine whether ignoring this law is a factor that contributes to malocclusion, temporomandibular joint dysfunction, and recurrences of functional orthodontic and orthopedic treatments.We conducted a search of the literature in five of the main electronic scientific databases. The following medical subject heading terms were used in our search: centric relation, dental occlusion, malocclusion, vertical dimension, and mastication. We cross-referenced the descriptors in the following four groups: centric relation and maximum intercuspation; occlusal plane and malocclusion; neuro-occlusal rehabilitation; and vertical dimension and unilateral chewing. From this, we selected 277 potentially eligible articles. Out of these, 209 were excluded in accordance with the exclusion criteria already described. Thus, 65 studies were included in the qualitative synthesis.The articles were also classified according to their impact factor and degree of recommendation, in conformity with the table of the Oxford Centre for Evidence-Based Medicine. The scientific interest in the scope of the articles was also assessed by using three charts developed according to year and country of publication and the percentage of publication. Unilateral chewing creates a vicious cycle of damage that leads to an ever-increasing masticatory deficiency. Most of the articles chosen for this review confirmed that noncompliance with law of MVD was a predisposing factor in cases of relapse, in functional orthodontic and orthopedic treatments, as well as a causal factor in malocclusion and in functional and morphological TMJ dysfunctions.