The rules of normality and canons of Aesthetics
Information through television and the press, advertising, fashion and modern life in general have made people more demanding about their physical appearance, where dental aesthetics plays an important role.
Being beautiful, being handsome, being young is a dominant concern of our civilization.
The orthodontist can no longer ignore this major desire of most of his patients.
The face has a primordial social function, but also carries within it the notions of identity, beauty and harmony. Cephalic morphology must ignore beauty in order to focus on measuring identity without losing sight of the notion of harmony, which will remain unquantifiable.
Cephalic anthropometry is the overall study of the shapes and reliefs of the anatomical regions of the head, in children during growth, then in adults.
Clues
- CEPHALIC INDEX
- The relationship between head length and width is established by the horizontal cephalic index (ICH)
Cephalic index = width×100length average value [75 to 80]
- The relationship between height and length is established by the height/length index
Height/length index = height×100length
- The relationship between height and width is established by:
Height/width index = height×100width
Variations in the horizontal cephalic index allow skulls to be classified into 5 categories:
- IC < 70: the skull is hyper dolichocephalic (very long and narrow).
- IC between 70 and 75: the skull is dolichocephalic (long and narrow).
- IC between 75 and 80: the skull is mesocephalic (average).
- IC between 80 and 85: the skull is brachycephalic (wide, short, rounded appearance).
- IC > 85: the skull is hyper brachycephalic (very rounded).
The shape of the skull varies with age; dolichocephalic at birth, the head takes on its morphological shape during growth, it varies further with sex; women are more brachycephalic than men.
For some authors this form also varies depending on the environment.
- Facial index: materializes the comparison between the height and width of the face
(Total height: On-Gn and width ZY-Zy)
- Total facial index:
Total facial index = Height On-Gn ×100 Bizygomatic diameter mean value [104-97]
- Much higher than 104, it indicates a hyper leptoprosopic face (very long and very narrow).
- Slightly greater than 104, indicates a leptoprosopic face; (narrow face).
- Between 104 and 97, this index reflects an average, mesoprosopic face.
- When this index falls below 97, the face becomes euryprosopic (wide and short).
- Much lower than 97, the index indicates a hyper euryprosopic face.
The difference between the sexes is expressed by a wider face in women than in men.
Most often in the same individual the facial index and the cephalic index vary in the same direction (e.g. brachycephalic is euryprosopic), nevertheless we can sometimes observe a wider face with a narrow head: we then say that there is a cephalofacial disharmony.
- Upper facial index:
Sup facial index = On-Pr height ×100 Bizygomatic diameter
The average upper facial forms are called mesenes, the most pronounced forms are called leptenes and euryenes and the excessive forms are called hyperleptenes and hypereuryenes.
There is a correlation between the facial index and the cephalic index, but sometimes there is a structural imbalance where e.g. a wide, low face accompanies a narrow head.
- arch width index – izard face
Arch width = Bizygomatic diameter2
Variation of the facial mass “facial type”
It is the study of the relationships that exist between bone architecture and profile shape. Several works have been developed in this area.
- BIMLER : proposes the “suborbital face index” based on the ratio between the depth of the tragion – subnasal and the height of the suborbital – chin and from which the following distinctions result:
- A low and deep dolichoprosopic face.
- A mesoprosopic face where height and depth are balanced.
- A high and shallow leptoprosope face.
- SASSOUNI: Determines the facial type according to the convergence of the basic planes of the skull, palatine, occlusal and mandibular. In the “deep-bite” with deep occlusion, these 4 planes generally tend towards parallelism. They are more convergent in “open-bite”.
- RICKETTS: distinguishes a brachyfacial, a mesofacial and a dolichofacial.
- tweed: front direction, middle direction, back direction.
- arch width index – izard face
Arch width = Bizygomatic diameter2
| facial type | Author | Face type |
| Anterior rotation | BJORK | Posterior rotation |
| Hyper divergent | SCHOUDY | hypo divergent |
| Deep-bite | SASSOUNI | Open-bite |
| VAT | MULLER | EVA |
| Brachycephalic | RICKETTS | Dolichocephalic |
| Dolichoprosope | BIMLER | Leptoprosope |
Relationship between incisor volume and transverse diameters of the upper arch:
PONT calculated 2 indices: Premolar index = Length of the arch Inc. ×10080 [D 4 G 4 ]
Molar index = Length of arc Inc. ×10064 [D 6 G 6 ]
- The DE NEVREZE index: measures the chord of the palate between the lingual necks of the second premolars as well as its arrow coming from the highest point of the vault perpendicular to the chord.
For this author, the curve of the vault is normal when this chord is double the arrow when the arrow is smaller than half the chord, the vault is low and the palate is flat, when the arrow is larger than half the chord, the vault is ogival.
The measurement of the depth and height of the palate generally accompanies that of the face in the transverse direction.
There is a common correlation between the shape and dimensions of the palatine vault and that of the nose, lips, and arches.
An ogival vault generally accompanies a narrow face with a pinched, upturned nose, everted lips and dental arches crowded due to insufficient transverse diameters.
- Clues
- Relationship between width and length of the upper arch: “Arch Index”
The arch index = max width×100max length Average value [115-130]
Variations in this value allow the classification of different arch shapes.
- Dolichove arch: index > 115
- Mesovian arcade: index [115-130]
- Brachyove arch: index < 130
There are 3 main shape patterns:
The ellipse: the most frequent, its ends tend to converge, it is elongated in dolichocephalics and shortened in mesocephalics
The parabola: premolar and molar aligned on straight lines which tend to diverge, the excessive shape tends towards the hyperbolic shape.
The U shape: the molars are located on both sides on parallel lines.
Between these three forms, there are all sorts of intermediaries: “lyre”, “horseshoe”, “semicircle”.
Profile Aesthetics
Merrifield places the pog, labial inf and sup points on a straight line forming an angle of 80° with the FrancFort plane, the point of intersection of these two straight lines is located halfway up the skin profile of the dorsum of the nose.
Burstone (1967) draws the subnasal line – pog in which the stomion should be located and in front of which the points, labial sup and inf, both at equal distance from the reference line, the average value is 2.8 +/- 1.83.
Steiner: draw a line that starts from the middle of the nasal S and passes through the pog, this line must be tangent to the lips.
Ricketts: gives the nose a predominant part since the nasal end serves as its reference system. The aesthetic line E connects the pronasion to the chin point. The lower lip must be flush with this line and the upper lip slightly set back from this line.
Conclusion
Knowledge of facial morphology standards is essential for the orthodontist who must recognize the malformation, assess its degree and predict the limits of its reduction.
A strong taste and an innate sense of aesthetics are not enough; we need reference bases, of which anthropometry is one, to take stock of each face and what needs to be preserved or restored, tolerated or modified.
Anthropometry applied to craniofacial analysis is far from being an obsolete science, and is an element to be taken into consideration in the development of orthopedic therapy .
The rules of normality and canons of Aesthetics
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