A life table analysis is a type of statistical method used to describe the survival in a sample (such as dental implants). The distribution of survival times is divided into intervals. For each interval, the number and proportion of cases that entered the respective interval “alive”(or in other words, that succeeded) can be computed as can the number and proportion of cases that “died” in the respective interval (or in other words, that failed). The number of cases that were lost to follow-up or that were censored in the respective interval can also be computed. This type of detailed statistical information is essential in determining which types of treatments, procedures, prostheses, or implants have the greatest rate of success within a group of recipients and are therefore more reliable than others that are available. This method may also be used to determine if a product should be approved for safe use or if it should be brought to market.
The term lingual means relating to, near, or on the side toward the tongue. It is often used to designate part of a tooth surface or to show the position of an anatomical region. As one of the most prominent structures of the mouth, the tongue is used to help identify the location of other oral structures. In regard to the teeth, there are five different surfaces including the lingual surface. The other four are the buccal surface which is on the side facing the inside of the cheeks, the distal surface facing the back of the mouth, the mesial surface which faces the front or forward part of the mouth, and the occlusal surface. This last term refers to the chewing surface of the teeth, specifically the bicuspids and molars. Other parts of the oral anatomy which pertain to the tongue include lingual artery, lingual nerve, and lingual plate.
The lingual artery is a branch of the external carotid artery, with a distribution to the undersurface of the tongue. It terminates as the deep artery of the tongue with subdivisions to the suprahyoid and dorsal lingual branches and the sublingual artery. The lingual artery is responsible for providing blood to the lower portion of the mouth including the tongue, the sublingual gland, and the floor of the mouth. In rare cases, the proximity of the lingual artery to the lingual cortex can cause complications during implant placement surgeries. Severe hemorrhage and resulting hematomas may occur and require immediate medical attention. With proper treatment, these complications have been shown to drastically improve within 48 hours with a more complete recovery apparent within a week. In order to prevent such complications, it is essential that practitioners remain educated concerning the surgical techniques required for anterior mandibular implants and to protect the soft tissues as much as possible.
The lingual nerve is a branch of the mandibular division of the trigeminal nerve. It lies inferior to the lateral pterygoid and medial and anterior to the inferior alveolar nerve. It supplies sensory innervations to the mucous membrane of the anterior two thirds of the tongue and the gingiva on the lingual side of the mandibular teeth. Most common dental surgeries and procedures should not come in contact with the lingual nerve however, some other procedures including the removal of the mandibular third molars and dental implant placement may cause damage. In third molar removal, three factors have been proven to have an impact on whether or not the lingual nerve is affected during a procedure. These factors are the prior experience of the surgeon, the age of the patient (older patients are at higher risk for damage), and the difficulty in accessing the third molars.
The lingual plate is the bony wall at the lingual aspect of an alveolus. It consists of alveolar bone proper and cortical bone with or without intervening cancellous bone. The lingual plate is often very thin and subject to fracture or damage during the removal of the mandibular third molar. Factors that may lead to the fracture of the lingual plate include the fusion of the tooth with the bone surrounding it, an older patient, and the size and shape of the root. Other issues that can cause damage to the lingual plate may come from the surgeon or practitioner. These issues include awkward or abrupt extraction movements, the use of chisels in some mandibular third molar removal procedures, and a sudden application of force. Due to the location of the lingual plate, it is possible that a lingual nerve injury may also occur if the plate is fractured or damaged.
The lip line is an important consideration for dental implantology. There are two lip lines — upper and lower. The lip line frames the anterior teeth that supports the lips, and is plays a significant role in the aesthetics of a patient’s smile. Ideally, a surgeon will be able to create an implant plan that reconciles lip and teeth positioning harmoniously. Prior to recommending dental implants, a dentist will evaluate the lip line and where it currently sits on the patient’s face in relation to their teeth and other facial structures. Lip lines are influenced by a variety of factors, including the shape of a patient’s lips and whether they are thin or full, the width and dimension of the oral cavity, and how visible supporting teeth are. It’s also important for a dental implant surgeon to verify that there is enough healthy ginvigal tissue to provide support.
During the aging process, changes occur to the face and mouth that can result in a less pleasing aesthetic appearance for patients. The upper lip begins to thin out and elongate, which results in an “aged” look when smiling. Many people turn to fillers to rectify this problem, however, they tend to accelerate the effects of aging. A lip lift is a cosmetic surgery procedure that is performed to shorten the area between the nose and the upper lip, called the upper philtrum. When the upper lip is shortened, the teeth are shown more when a patient smiles or speaks and helps restore a healthy-looking appearance. A lip lift has a significant impact on cosmetic dentistry, from how many teeth show when speaking or smiling to how a person’s “V” and “F” sounds come across. A lip lift is a relatively simple outpatient surgical procedure that results in little to no scarring.