Analysis of the lower jaw before insertion of the implant
Last reviewed: 23.04.2024
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The presence of an underdeveloped chin is the most frequent indication of its increase. The basic principles of aesthetic proportions of the face were summarized in the work of Powell and Humphreys; they include frontal and lateral evaluation. The face in direct projection can be divided into thirds, the lower of which is limited to the sub-nasal and menton. It, in turn, can also be divided into thirds so that the upper third will be between the subnazal and the upper sto- mion, and the lower two thirds between the lower sto- mion and the menton. With age, there is a decrease in the vertical height and anterior protrusion of the lower jaw, which leads to a loss of the ideal proportion. To determine the underdeveloped chin in the side view, the Gonzales-Ulloa method can be used. This technique determines the protrusion of the chin as an aesthetic when the anterior soft-tissue chin point, the chase, touches a vertical line dropped from the nazion, perpendicular to the Frankfurt plane. If the chin is located posteriorly from this line and there is an occlusion of the first class, the underdevelopment of the chin is noted. The underdeveloped chin can be the result of microgena, a small chin formed due to underdevelopment of the mandibular symphysis, or micrognathia due to hypoplasia of various parts of the lower jaw. The enlargement of the lower jaw is usually done about microgenia and cases of small micrognathia. The most evaluation of the patient's occlusion. The increase is most suitable for patients with microgenia and normal or almost normal bite.
Although congenital factors contribute to the presence of chin hypoplasia, the development of the anterior frontal groove of the lower jaw is mainly due to age-related changes. Loss of elasticity of the skin of the eyelids, face, neck and sub-chin is the most obvious and often observed signs of aging. There are also minor changes in the configuration of the anterior mandibular region, which can have a significant effect on the face. As a result of progressive soft tissue atrophy and the gradual loss of bone tissue in the area between the chin and the lateral sections of the lower jaw, a groove known as the anterior mandibular groove may form in the patients between the chin and the rest of the lower jaw.
In the formation with age of the anterior mandibular groove two main factors are involved. The first is the resorption of the bone tissue of the lower jaw at the junction of its central (chin) and anterolateral sections. In the manuals on anatomy it is shown that the area below the chin opening undergoes resorption and becomes concave. It is called the anterior mandibular groove. This furrow, located on the surface of the bone, is reflected on the outer surface of the soft tissues as a notch between the buccal part of the lower jaw and the chin and is called the anterior mandibular groove. Another important factor in the formation of the anterior mandibular groove is the atrophy of the soft tissues of this region in the process of aging. Over time, this line becomes part of the oval that delineates the mouth and is called the "line of the puppet" or "the line of the bib". Most people who develop an anterior mandibular fossa develop with age, it is often the result of a combination of soft tissue atrophy and bone resorption in the area between the chin and the cheek parts of the lower jaw.
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