Genetic Dental Abnormalities: Types and Symptoms
Genetic mouth/dental abnormalities (anomalies) are problems, dysfunctions and diseases of oral tissues and dentition caused by defective genes. Many genetic dental/oral abnormalities indicate more complex disorders and are linked to inherited traits and defects, or result from spontaneous genetic mutations.
Types of Genetic Oral/Dental Abnormalities
Cleft Lip & Cleft Palate: The most common craniofacial deformity is clefting of the lip and palate. Clefting, the incomplete fusion of the lip and/or palate, can appear alone or as part of a hereditary syndrome. Family history of clefting increases the chances of inheriting the disorder. Cleft lip with or without a cleft palate occurs most frequently among Asians. Seen more often in boys than girls, cleft lip or “harelip” usually appears on one side, most often on the left. A bilateral or two-sided cleft is less common. An incomplete cleft stops short of the nostril; a complete cleft goes into the nostril. Both cleft types often involve the palate. A typical patient with cleft palate/cleft ridge has defects in the roof of the palate, with an opening into the nasal cavity.
Anodontia/Hypodontia: Anodontia, also called congenitally missing teeth, is a hereditary condition in which one or more permanent teeth do not develop, though primary (baby) teeth usually erupt. Anodontia may involve the absence of all (total anodontia) or only some (hypodontia) teeth. Hypodontia – which alters bone development of the upper and lower jaws, resulting in spacing problems – is more common in males; incidence varies among populations. Third molars, maxillary (upper) lateral incisors, and maxillary and mandibular (lower) second premolars (bicuspids) are the teeth that most frequently fail to appear.
Amelogenesis Imperfecta and Dentinogenesis Imperfecta: Amelogenesis imperfecta, an inherited disorder, results in the defective formation of tooth enamel, the hard surface covering tooth crowns. Amelogenesis imperfecta either causes problems in enamel hardening (mineralization) of normal amounts of enamel, or causes less than normal enamel production. Dentinogenesis imperfecta is a genetic disorder causing defective formation of dentin, the mineralized material composing the majority of all tooth structure. Defective dentin causes the normal enamel layer covering it to flake off. Both diseases can affect baby and permanent teeth, leaving them weak, sensitive to temperature and pressure, and prone to quick wear.
Supernumerary Teeth: Supernumerary teeth are extra permanent teeth that may or may not erupt. Many are abnormally shaped and can appear anywhere in the mouth. The most common supernumerary teeth are mesiodens, small teeth with a cone-shaped crown and a short root located between the maxillary central incisors. Supernumerary teeth also are common in the upper molar area (distomolars or fourth molars).
While other factors are also thought to contribute, heredity is believed to play a role in the development of supernumerary teeth, since they are more common in relatives of affected children than among the general population. Multiple supernumerary teeth are rare in people with no other associated diseases or syndromes. Conditions frequently associated with a higher incidence of supernumerary teeth include cleft lip/palate, cleidocranial dysplasia (a genetic disorder affecting bone and teeth development) and Gardner syndrome (inherited disorder leading to colon cancer).
Malocclusion: Also called a bad bite, malocclusion is caused by crowded, extra or missing teeth, or jaws out of alignment. Most malocclusions are inherited genetically and can lead to temporomandibular jaw (TMJ) disorders that can result in problems chewing and speaking. The objective of the diagnosis, and surgical and non-surgical management of malocclusions and potential TMJ complications, is to restore normal function and eliminate pain.
Periodontal (Gum) Disease: Gum disease refers to bacterial infection and inflammation causing damage to soft and hard tissues supporting the teeth. In its early stages (gingivitis), gums become red, swollen and bleed easily, but the disease is reversible. In advanced stages of periodontal disease (periodontitis), gums and bone supporting the teeth become seriously damaged, resulting in loose teeth that may fall out or need removal by a dentist. Although primarily an infectious disease caused by poor oral hygiene, gum disease is influenced by heredity. An association between gum disease and several systemic conditions such as heart disease, stroke, diabetes and preterm babies has also been suggested.
Gingival Fibromatosis: A hereditary condition causing an overgrowth of the gum tissue, gingival fibromatosis is characterized by enlarged gum tissue and is associated with an overproduction of collagen.
Oral Cancer: Often starting as a tiny, inconsequential white or red spot or sore anywhere in the mouth, most oral cancers often occur in people who use tobacco and alcohol and are most likely to strike after age 40. However, genetic factors also play a role. These include hereditary predisposition, oncogenes (genes that change growth patterns) and mutations in tumor suppressor genes. Someone with a hereditary predisposition for cancer has a greater chance of developing cancer due to inherited genes, which make body cells more sensitive to cancer-contributing factors such as tobacco, alcohol and sunlight. Mutation in an oncogene may convert ordinary body cells into cancer cells. Mutations of normal tumor suppressor genes – which are anti-cancer genes that slow down or stop the growth of normal body cells – also can give rise to oral cancers.
Canker Sores: Canker sores are small ulcers with a white or gray base and a red border that appear inside the mouth. Non-contagious, canker sores can recur frequently. Immune system problems, bacterial infections or hereditary predisposition may be possible causes. Fatigue, stress, food allergies or menstrual cycles may increase the chances of canker sore development. In some cases, canker sores are associated with an underlying systemic disease. Inflammatory bowel diseases such as ulcerative colitis (inflammation affecting the lining of the colon and rectum) and Crohn’s disease (inflammation affecting the full thickness of gastrointestinal mucosa from mouth to rectum), as well as Celiac sprue (an intestinal disorder caused by intolerance of gluten in dietary wheat products), tend to run in families and seem to make people more susceptible to recurrent bouts of canker sores.
If you suspect that your dental/oral problems are caused by a genetic abnormality, visit your dentist as soon as possible to discuss your symptoms and undergo an examination. Your dentist will likely review your complete medical history and perform a thorough oral examination in order to help identify the cause of your dental/mouth problems and provide appropriate treatment and referral.
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