Aging and Sexual Differences of the Human Skull

Luiz Eduardo Toledo Avelar, MD; Márcio Alberto Cardoso, MD; Leonardo Santos Bordoni, PhD; Lorena de Miranda Avelar; João Victor de Miranda Avelar

Disclosures

Plast Reconstr Surg Glob Open. 2017;5(4):e1297 

In This Article

Abstract and Introduction

Abstract

Background: The aging process of the face comprises all layers: skin, subcutaneous fat, muscles, and skeleton, and the signs of aging depend mainly on which layer is mostly affected.

Objective: To evaluate the aging facial skeleton, as well as establish the sexual differences, areas with a strong predisposition to resorption, and aesthetic repercussion for better treatment approach.

Methods: Skulls from the Forensic Anthropology Department of the Institute of Forensic Medicine of Belo Horizonte, Brazil, were classified according to gender and age group (i.e., <20 years, 20–50 years, >50 years). Structural changes were classified according to gender and age group.

Results: Of the 241 skulls included, 192 were male skulls and 49 female. Sexual dimorphism and age-related peculiarities are described herein.

Conclusions: The knowledge of the anatomy of the aging face, taking into consideration all the layers (skin, fat pads, muscles, and bones), as a whole, for the treatment of folds and shadows is vital for a better and more natural final aesthetic outcome.

Introduction

Despite being more remarkable at adult age, the aging process begins since birth, and continues throughout the whole life, due to genetic and external factors, such as UV exposure and smoking. The face, in most cultures, is one of the most exposed areas of our bodies, so that the aging process is not only earlier, but more easily recognizable. The aging process comprises all layers of the face: skin, subcutaneous fat, muscles, and skeleton, and the signs of aging depend mainly on which layer is mostly affected. Aging may affect the skin in terms of quantity (skin sagging) and/or quality (changes in skin hydration, appearance of spots and wrinkles). There is a reduction of the collagen content of the skin, not only due to decrease in synthesis, as a process of intrinsic aging, but also due to extrinsic factors, such as UV radiation, which may generate reactive oxygen species (ROS), leading to an increment in collagen breakdown by upregulating enzymes called matrix metalloproteinases.[1] The decrease of collagen content may also affect deeper layers of the face. The loss of the subcutaneous facial fat compartments with age leads to the appearance of increased skin laxity or prominent folds around the nasolabial region, periorbital region, and jowl.[2] The muscles may present hypo- or hypertonicity (i.e., glabella, masseter) depending upon the use and area of the face. The bone is a dynamic, sensitive, ever-changing tissue. Bone growth takes place from birth until the hormonal stimulus ceases, with long bone epiphysis consolidation usually around 15–18 years of age. On the other hand, bone remodeling continues throughout life, determined not by intrinsic factors, but mainly by regional changes in the soft tissues related to each bone, such as muscles, tongue, lips, skin, brain, among others.[3,4] Bone remodeling serves to adjust bone architecture to meet changing mechanical needs, repair microdamages, and guarantee calcium homeostasis.[5] Therefore, it is transitory and does not involve the totality of the bone. The process of bone remodeling involves the removal of mineralized bone by osteoclasts and the formation of bone matrix through the osteoblasts. Both processes of bone remodeling occur throughout life, although the balance between them changes according to the period of life. Bone formation is more prominent in childhood; the processes are balanced in adults, although bone resorption is more prominent in the elderly. Among the theories of bone remodeling, the Functional Theory correlates bone remodeling to response to demand. When the bone is submitted to traction by a hypertrophic muscle or subcutaneous fat distension, a local demand is generated and bone is produced in that area. On the other hand, continuous pressure on the bone (e.g., silicon chin prosthesis) or intense muscle, ligament or skin laxity, may lead to bone resorption.[3,4] The objective of this study is to evaluate the aging facial skeleton, and establish the sexual differences, areas with a strong predisposition to resorption and aesthetic repercussion for a better treatment approach.

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