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Study of the Aesthetic Criteria for the Zygomatic Area and the Clinical Research of Malar Reduction Plasty

Graduate dissertation for PhD Degree in Medicine
[ Author:Dr. Fushun Ma | Time:2011-10-20 09:21:08 |  Font Size: [Large Medium Small]
Tags: reduction malar plasty, zygoma reduction, zygomatic arch

Dr. Fushun Ma

Tutor: professor Zongji Chen

Abstract

The Facial outline can be contoured to correct deformities and improve the cosmetic out-looking. Zygomatic area is in the middle of the face and plays an  important role in the formation of the facial outline. The appearance of the area is dominated by the zygoma and the zygomatic arch, which lies beneath the skin and the subcutaneous tissue. The zygoma and zygomatic arch plasty constitute the main part of facial contour. In order to contour the facial skeleton, we must have a good awareness of the skeleton structure. In the past the structural studies put the stress on the maxillofacial area, there is hardly any of studies deal with the zygomatic area.

The research studies the aesthetic criteria of the human face on the zygomatic area, and than studies the surgery of the over protruding zygoma and zygomatic arch. The fundamental study includes facial skeleton analysis, facial form and surface dimension analysis and computer aided design, which concerns the facial skeleton structure , X-ray image analysis, surface structure analysis of the zygomatic area and the application of computer design in the surgery of zygoma and zygomatic arch. The clinical study concerns the diagnosis, treatment, surgery design and procedure of the over prominence deformity of the zygomatic area.

Facial Skeleton Analysis for the Malar Bone

76 skulls were surveyed by the method of direct measurement. 20 dimensions between 9 points per skull, 1520 dimensional data were obtained.

By the observation and analysis of 100 skulls, it was found that the most frontal-lateral prominent point of the zygoma locates at the middle of the line drawing between the jugale and the zygomaxillare. The point was named the Zygomatic Prominence point which represent the frontal-lateral prominence of the zygoma in skull survey.

By the measurement of specially prepared X-ray image, the X-ray expression of 10 cases with over prominence deformity and 40 cases of control group were analyzed.

Values that represent the dimension of facial skeleton and relationship of different parts were derived from the skull survey. The ratio of front face width to minimum frontal width is 1.2127+0.0823, and face width to minimum frontal width is 1.4567+0.0797. The values are useful in zygomatic surgery.

The comparison between skull survey and X-ray image survey revealed that though the magnification existing, the relationship of different parts remained as it was.

The values of dimension between left and right side of the skulls differed from each other, but no significance revealed after statistical data processing. This indicates that the bone structure of the examined skull is symmetry in left and right side.

Facial Pattern and Malar Measurement

The facial formation and zygomatic area of 200 young volunteers were surveyed by the method of direct measurement. 100 of them were male and the others were female. All the volunteers, born in the north area,  aged 18 to 22, had a normal looking face without facial deformity, belonged to HAN nationality. 30 dimensions between 13 points per candidate, 6000 dimensional data were obtained.

A triangle method was put forward to investigate the frontal-anterior prominent degree of the zygomatic area. By this method the height of the zygomatic prominent can be calculated only through some facial surface dimension.

The relationship between facial length and width determines the optical expression of facial length and width. The relationship between upper or lower face and the middle face determines the optical expression of facial roundness. According to this a new method of digital facial form analysis is suggested. e.g. using the facial width index the face can be divided into wide type with a index value larger than 1.93(female 1.97), medium type with a index value between 1.71 to 1.93(female 1.77 to 1.97) and narrow type with a index minor than 1.71(female 1.77).

In the lateral point of view the middle face protruding index divides the face into normal, bird like and dish-like.

In the horizontal point of view the orbital, maxilla and mandible arch index divides the upper, middle and lower lateral face into protruding, normal and flat.

The values of dimension between left and right side of the face differed from each other, but no significance revealed after statistical data processing. This indicates that the surface structure of the examined face is symmetry in left and right side.

The Application of Computer Assistant Design in Malar Surgery

The hardware, software and X-ray factor for computer aided design in zygomatic area skeleton plasty were discussed. Some measurements to control the morphotropy of X-ray image were derived. By the application of computer and mathematical rules, the real length of the irregular zygomatic arch was calculated. A method of estimating the length of removal in compound osteoectomy zygomatic arch reduction was designed. Compared with CT image the X-ray image is easy and practical in computer aided zygomatic plasty design as some bone marks are easier to read in X-ray image than in plain CT image.

Clinical Study

12 cases of over prominent zygoma deformity were reported. All the patients achieved better facial structure after operation. On the bases of reported zygomatic osteoectomy, a new method of  zygoma and zygomatic arch compound osteoectomy was applied in zygoma area reduction plasty. In this method the osteoectomy point was selected in the most protruding point of the zygomatic arch, certain length of the arch was removed and the remained  parts of the arch were jointed and fixed after a green stick fracture on its root. By this way we can design the reduction freely, control the osteoectomy and post operation result more precisely. The detailed preoperative design made the operative procedure quick and brief. Most of the blood supply of the arch remained, so the heeling is also quick. From the study we derived that the principle of plastic and cosmetic surgery should be based on precise and detailed preoperative design employing  the modern technique as much as possible to achieve a quick and brief operating procedure. Thus the post operative result will become more predictable and the operation itself will be safer and more acceptable.

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