Macrodontia (tooth)

Last updated
Macrodontia (tooth)
Other namesMegadontia, megalodontia
Specialty Dentistry

Macrodontia is a type of localized gigantism in which teeth are larger than normal. Macrodontia seen in permanent teeth is thought to affect around 0.03 to 1.9 percent of the worldwide population. Generally, patients with macrodontia have one or two teeth in their mouth that is abnormally large; however, single tooth growth is seen in a number of cases as well.

Contents

The three types of macrodontia are true generalized macrodontia, relative generalized macrodontia, and macrodontia of a single tooth. True generalized macrodontia is very rare while Macrodontia of a single tooth is much more commonly seen. Macrodontia should not be confused with other oral conditions such as taurodontism (bull teeth), fusion (double tooth), or the jaws being relatively small, giving the appearance of macrodontia.

Signs & Symptoms

As is customary with all aspects of medicine, people have unique inherent differences in terms of their physiology which constitute their individuality. This holds true in dental morphology as well, as people come with different shapes and sizes of teeth; however, people in general have teeth with dimensions which are proportional to the size of their jaw. Specialists are usually able to identify signs of macrodontia upon first glance also given the irregularity in appearance of the tooth in reference to other teeth present as well as what is expected for a patient in terms of tooth size given their age and gender. [1]

There are several symptoms associated with macrodontia, including:[ medical citation needed ]

Causes

Macrodontia is not an abnormality which occurs abruptly during adulthood, rather, it happens while the teeth grow. Causes of macrodontia are still under research and an area of study within pediatric dentistry. Commonly, however, macrodontia is associated with genetic syndromes such as otodental syndrome, insulin-resistant diabetes, facial hemihyperplasia, KGB syndrome, Ekman-Westborg-Julian syndrome, and 47 XYY syndrome. Researchers note that genetic mutations which regulate tooth growth could cause teeth to grow abnormally.[ medical citation needed ] Some of these genetic conditions associated with this disease are also related with hormonal imbalances and are likely related to the pituitary gland, resulting in deviant tooth growth. [2]

In addition, factors during early childhood have been shown to play a significant role in the development of macrodontia; diet, exposure to toxins or radiation and other environmental factors increase the likelihood of macrodontia growth. [3]

Pathophysiology

Although researchers concede that the actual cause of macrodontia is unknown, there are a number of key causes of this disease which are worth mentioning to understand how this disease originates. Two key mechanisms that are commonly referred to in scientific literature surrounding this condition is how patients suffering with pituitary gigantism exhibit macrodontia as well as those with the genetic disorder KBG syndrome.

Gigantism is a syndrome that causes the excessive secretion of growth hormone (hypersomatotropism) due to a pituitary adenoma. Growth hormones are critical for stimulating somatic growth and regulation a person's metabolism. Growth hormone release hormone, or GHRH, is the key stimulator while somatostatin is the critical inhibitor of the synthesis and release of growth hormone. [4] Growth hormone controls the synthesis of insulin-like growth factor 1, or 1GF-1), which controls growth of the body. IGF-1 is produced principally by the liver, but also by the tissues in the body. Growth hormone will initially exhibit insulin-like effects by increasing the glucose uptake in muscle and fat and stimulating the amino acid uptake and protein synthesis in the liver and muscles, while also inhibiting lipolysis in the adipose tissue. Growth hormone- secreting adenomas will contain a mutant form of the Gs protein; this protein is a stimulatory regulator of adenylate cyclase. [4] Cells containing this mutant form of the Gs protein will continue to secrete growth hormone even in the absence of the growth hormone-releasing hormone (GHRH). Growth hormone is known to increase the formation of bone and hard tissues of the tooth, such as dentine, cementum, and enamel. [4] The growth hormone receptors that are seen in these tissues mediate the local growth responses. And because cells with this mutant form of the Gs protein continue to secrete GH, this could result in the overgrowth of teeth in a patient. Thus, macrodontia is exhibited due to the overexpression of GH through a form of gigantism.

Another key syndrome which results in the expression of macrodontia is KBG syndrome. This is a rare congenital genetic syndrome that is characterized by facial dysmorphism, macrodontia of the permanent upper central incisors, and other skeletal abnormalities. KBG syndrome is caused by a mutation within the ANKRD11 gene or the loss of genetic material on chromosome 16q which involves the ANKRD11 gene. [5] This mutation can occur spontaneously with no family history or be inherited in an autosomal dominant manner. [6] This gene is known to interact with nuclear receptor complexes in order to modify transcriptional activation, [6] while also having a critical role in dental, craniofacial, skeletal, and CNS development and function. As a result of this mutation, the regulation of the development of these areas, namely in terms of proper tooth development, are diverged, resulting in abnormalities in the skeletal and dental systems. In essence, the mutation of this gene leads to conditions to KBG syndrome which has symptoms such as macrodontia as a result of uncontrolled growth of these areas. [6]

Diagnosis

Diagnosis of macrodontia by a dental specialist is first obtained by simple observation, measurement, and comparison with the standard tooth size; this is then later accompanied by conducting a radiological investigation which can be done in a variety of ways.

For a dental specialist to begin the process of diagnose a patient with macrodontia, there needs to be clear signs that there is an abnormality in regards to the size of the tooth in reference to surrounding teeth and average tooth sizes. This is done by noting any disproportions between the teeth and the maxilla. [7] In general, when a patient is seen to have a tooth that is more than two standard deviations larger than the average for their age and gender, it is a major indication of macrodontia at play; this is done using X-rays and can help indicate macrodontia of teeth that have already erupted as well as those that are unerupted. [7]

As is customary for the identification of most dental anomalies of tooth morphology, radiographic investigation is done following the physical examination. Level 1 radiographic examination for suspected macrodontia, however, should only be done after considering the patient's medical records (positive medical history of congenital syndromic conditions related to genetic disorders), the clinical signs and symptoms (the enlarged tooth shape/size), as well as the risk/benefits of exposure to harmful radiation. [8] A specialist may also recommend a different type of radiographic investigation, orthopantomography and intraoral radiography, as a suitable imaging technique. [8] This allows for the imaging of both jaws in a single two-dimensional image as well as reduced radiation; this is reserved for cases where level 1 radiographic investigations are unable to provide adequate information. Additionally, when two-dimensional imaging like the recommendations previously mentioned are unable to provide enough clear information regarding the anatomical relationship of the macrodontia affected tooth with surrounding anatomical structures, the use of CBCT is recommended. [8] The 3D CBCT imaging technique must be as targeted to the area in question as possible as to minimize the exposure of radiation to the patient while also maintaining optimal spatial resolution. [8] Using these imaging techniques, dentists will be able to make an accurate diagnosis of macrodontia as well as the type of macrodontia the patient suffers from.

Types of macrodontia

True generalized

In true generalized macrodontia, all teeth grow in larger than normal. This is a symptom of rare genetic disorder cases of growth hormone excess called pituitary gigantism. Other patients may have a disease called Rabson-Mendenhall syndrome which predisposes to generalized macrodontia. This causes insulin resistance and is an autosomal recessive disorder. [9]

Relative generalized

All teeth appear slightly larger than normal; usually, the jaws are smaller than average. It is sometimes called "pseudomacrodontia", as small jaws give the illusion that the teeth are abnormally large. Genetics play a major role in this type of macrodontia; offspring inherit small jaw size from one parent and relatively large teeth from the other parent. [10]

Single tooth

A single tooth is larger than the rest. This is unusual and could be the result of fusion and germination that cause enlarged crowns. [10]

Treatment

Following a proper diagnosis by a dental specialist, they will recommend a specific course of treatment based on the severity of the disease. Because the nature of macrodontia is mostly due to genetic syndromes, the specialist will likely recommend that a patient visit a cosmetic dentist. There are three main procedures which can be done by the cosmetic dentist to improve the look of the teeth affected, these include: orthodontics, teeth shaving, and teeth removal.

Macrodontia can result in the misalignment of the affected tooth as well as the neighboring anatomical structures. Orthodontics can assist in straightening the teeth as well as expansion of the jaw if necessary. This is done by using a palate expander which can stretch the patients jaw as to better fit the teeth in a patient's mouth. To counter the tooth crowding as a result of macrodontia, an orthodontist may suggest braces and a retainer to help straighten the teeth to minimize additional misalignment and thus make the teeth appear smaller. This is mostly a treatment for the neighboring teeth as a result of macrodontia of a tooth.

Another cosmetic approach to macrodontia is through teeth shaving, also commonly referred to as tooth recontouring.[ citation needed ] During this treatment method, a dental specialist will use a gentle sanding device to shave and reduce the size of the tooth. This results in a slightly smaller tooth which may improve visual appearance. This method is generally a safe option for patients with macrodontia who have healthy, strong teeth. This is because if the tooth is too weak, then shaving down a tooth will instead increase sensitivity as well as the possibility of decay. This is a common method of treatment for those with medium to mid-severe cases of macrodontia.[ citation needed ]

A last-method approach to combat macrodontia is also to simply remove the affected tooth to make more space for the neighboring teeth. By doing so, this will make the teeth appear less crowded and smaller.[ citation needed ] Those patients that take this route of treatment usually get the affected tooth removed and replace it with dentures or false teeth to enhance the appearance of the mouth. This method is usually used for those who are suffering from a great deal of pain as a result of the overgrown tooth and can not be treated by the other two methods mentioned previously; this is usually the safest route in that case. This treatment option is mostly reserved for severe cases of macrodontia where the patient suffers from severe jaw joint pain as a result of the affected tooth.

Prognosis

Macrodontia is not a lethal disease, rather, it is a disorder which affects the physical appearance of the teeth and can have implications with the surrounding teeth, thereby affecting the overall positioning of the teeth, jaw pain, and other crowding issues resulting in future misalignment.[ citation needed ] There is no empirical data regarding the effects of macrodontia on life expectancy or the likelihood of remission. This is because once the tooth is either shaved or fully removed, there is no chance of the macrodontia returning, as it is not contagious.

In terms of long term effects, there are a number of complications which can develop as a result of untreated macrodontia. As previously mentioned, the problem that occurs with having teeth that are overly large is that, aside from the abnormal appearance, they can have lasting impacts on the mechanics of a patient's bite, rendering its effectivity much lower than it would be with properly sized teeth. [2] As a result, patients would have long lasting issues with their bite alignment as well as continuous jaw joint pain as a result of having a deviate bite. The development of dental caries due to the abnormal morphology of the overgrown tooth can be more of a short-term impact that can result in long lasting effects of overall tooth health. This is because unless the patient gets treated, these caries will continue to develop and eventually result in continued degradation of the tooth and cause infections to surrounding teeth and gums. [2]

Epidemiology

Macrodontia is a very uncommon dental abnormality which has been reported alongside other dental anomalies. It is reported that macrodontia affects 0.03% of the population. Males seem to have a higher predisposition to the disease, with a prevalence of 1.2%. On the other hand, females have a prevalence of around 0.9%. [11]

Disruptions of regular growth of the teeth and enlargement usually become evident before or between the ages of 11 and 12, when the eruption of the mandibular second premolars usually occur. [12]

Research Direction

While there is research regarding the symptoms and effects of macrodontia on patients, there is still a fundamental misunderstanding regarding the specific pathophysiological mechanisms that are exhibited which result in this abnormality. [12] Current research has been able to clearly identify methods of observing and diagnosing a patient by using various imaging techniques. [8] There is also an abundance of information regarding treatment options that are mostly concentrated within the cosmetic branch of dentistry to fix the appearance of the teeth as well as simply removing it to halt continuous pain. [8] There is a number of genetic mutations that have been correlated with the prevalence of macrodontia in patients exhibiting this syndrome, such as KBG syndrome or those who overexpress GH, but how this relates to the hard tissue of the teeth and the mechanism by which it affects the enamel and other related factors have yet to be considered. There is no current clinical trials for treatment of this disease as there are a number of procedures which already exist to make the affected teeth smaller; and if all else fails, dentists can simply remove the tooth and replace it with a veneer or bridge in its place.

Related Research Articles

<span class="mw-page-title-main">Human tooth</span> Calcified whitish structure in humans mouths used to break down food

Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.

<span class="mw-page-title-main">Gigantism</span> Human growth disorder

Gigantism, also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by over-production of growth hormone in childhood.

<span class="mw-page-title-main">Incontinentia pigmenti</span> Rare X-linked dominant genetic disorder

Incontinentia pigmenti (IP) is a rare X-linked dominant genetic disorder that affects the skin, hair, teeth, nails and central nervous system. It is named from its appearance under a microscope.

Hypodontia is defined as the developmental absence of one or more teeth excluding the third molars. It is one of the most common dental anomalies, and can have a negative impact on function, and also appearance. It rarely occurs in primary teeth and the most commonly affected are the adult second premolars and the upper lateral incisors. It usually occurs as part of a syndrome that involves other abnormalities and requires multidisciplinary treatment.

<span class="mw-page-title-main">Ectodermal dysplasia</span> Group of genetic conditions affecting the embryonic ectoderm

Ectodermal dysplasia (ED) is a group of genetic syndromes all deriving from abnormalities of the ectodermal structures. More than 150 different syndromes have been identified.

<span class="mw-page-title-main">Macroglossia</span> Medical condition

Macroglossia is the medical term for an unusually large tongue. Severe enlargement of the tongue can cause cosmetic and functional difficulties in speaking, eating, swallowing and sleeping. Macroglossia is uncommon, and usually occurs in children. There are many causes. Treatment depends upon the exact cause.

<span class="mw-page-title-main">Malocclusion</span> Medical condition

In orthodontics, a malocclusion is a misalignment or incorrect relation between the teeth of the upper and lower dental arches when they approach each other as the jaws close. The English-language term dates from 1864; Edward Angle (1855-1930), the "father of modern orthodontics", popularised it. The word "malocclusion" derives from occlusion, and refers to the manner in which opposing teeth meet.

<span class="mw-page-title-main">Cherubism</span> Medical condition

Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby-cheeked resemblance to putti, the chubby-faced infants featured in Renaissance paintings, which were often mistakenly described as cherubs.

<span class="mw-page-title-main">Dentinogenesis imperfecta</span> Medical condition

Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development. It is inherited in an autosomal dominant pattern, as a result of mutations on chromosome 4q21, in the dentine sialophosphoprotein gene (DSPP). It is one of the most frequently occurring autosomal dominant features in humans. Dentinogenesis imperfecta affects an estimated 1 in 6,000-8,000 people.

Anodontia is a rare genetic disorder characterized by the congenital absence of all primary or permanent teeth. It is divided into two subsections, complete absence of teeth or only some absence of teeth. It is associated with the group of skin and nerve syndromes called the ectodermal dysplasias. Anodontia is usually part of a syndrome and seldom occurs as an isolated entity. There is usually no exact cause for anodontia. The defect results in the dental lamina obstruction during embryogenesis due to local, systemic and genetic factors.

Dilaceration is a developmental disturbance in shape of teeth. It refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth. This disturbance is more likely to affect the maxillary incisors and occurs in permanent dentition. Although this may seem more of an aesthetics issue, an impacted maxillary incisor will cause issues related to occlusion, phonetics, mastication, and psychology on young patients.

<span class="mw-page-title-main">Microdontia</span> Medical condition

Microdontia is a condition in which one or more teeth appear smaller than normal. In the generalized form, all teeth are involved. In the localized form, only a few teeth are involved. The most common teeth affected are the upper lateral incisors and third molars.

<span class="mw-page-title-main">Dentin dysplasia</span> Medical condition

Dentin dysplasia (DD) is a rare genetic developmental disorder affecting dentine production of the teeth, commonly exhibiting an autosomal dominant inheritance that causes malformation of the root. It affects both primary and permanent dentitions in approximately 1 in every 100,000 patients. It is characterized by the presence of normal enamel but atypical dentin with abnormal pulpal morphology. Witkop in 1972 classified DD into two types which are Type I (DD-1) is the radicular type, and type II (DD-2) is the coronal type. DD-1 has been further divided into 4 different subtypes (DD-1a,1b,1c,1d) based on the radiographic features.

Rabson–Mendenhall syndrome is a rare autosomal recessive disorder characterized by severe insulin resistance. The disorder is caused by mutations in the insulin receptor gene. Symptoms include growth abnormalities of the head, face and nails, along with the development of acanthosis nigricans. Treatment involves controlling blood glucose levels by using insulin and incorporating a strategically planned, controlled diet. Also, direct actions against other symptoms may be taken This syndrome usually affects children and has a prognosis of 1–2 years.

3-M syndrome or 3M3 is a rare hereditary disorder characterized by severe growth retardation, facial dysmorphia, and skeletal abnormalities. The name 3-M is derived from the initials of the three researchers who first identified it: Miller, McKusick, and Malvaux and report their findings in the medical literature in 1972. Mutations in any one of the following three genes: CUL7, OBSL1, and CCDC8 are responsible for the occurrence of this disorder. It is inherited through an autosomal recessive pattern and considered very rare, so far less than 100 cases worldwide have been identified. Diagnosis is based on the presence of clinical features. Genetic testing can confirm the diagnosis and identify the specific gene involved. Treatment is aimed at addressing the growth and skeletal problems and may include surgical bone lengthening, adaptive aids, and physical therapy. An endocrinologist may assist with growth hormone replacement and appropriate evaluations during puberty.

<span class="mw-page-title-main">Tricho–dento–osseous syndrome</span> Medical condition

Tricho–dento–osseous syndrome (TDO) is a rare, systemic, autosomal dominant genetic disorder that causes defects in hair, teeth, and bones respectively. This disease is present at birth. TDO has been shown to occur in areas of close geographic proximity and within families; most recent documented cases are in Virginia, Tennessee, and North Carolina. The cause of this disease is a mutation in the DLX3 gene, which controls hair follicle differentiation and induction of bone formation. All patients with TDO have two co-existing conditions called enamel hypoplasia and taurodontism in which the abnormal growth patterns of the teeth result in severe external and internal defects. The hair defects are characterized as being rough, course, with profuse shedding. Hair is curly and kinky at infancy but later straightens. Dental defects are characterized by dark-yellow/brownish colored teeth, thin and/or possibly pitted enamel, that is malformed. The teeth can also look normal in color, but also have a physical impression of extreme fragility and thinness in appearance. Additionally, severe underbites where the top and bottom teeth fail to correctly align may be present; it is common for the affected individual to have a larger, more pronounced lower jaw and longer bones. The physical deformities that TDO causes become more noticeable with age, and emotional support for the family as well as the affected individual is frequently recommended. Adequate treatment for TDO is a team based approach, mostly involving physical therapists, dentists, and oromaxillofacial surgeons. Genetic counseling is also recommended.

<span class="mw-page-title-main">Otodental syndrome</span> Medical condition

Otodental syndrome, also known as otodental dysplasia, is an exceptionally rare disease that is distinguished by a specific phenotype known as globodontia, that in rare cases can be associated with eye coloboma and high frequency hearing loss. Globodontia is an abnormal condition that can occur in both the primary and secondary dentition, except for the incisors which are normal in shape and size. This is demonstrated by significant enlargement of the canine and molar teeth. The premolars are either reduced in size or are absent. In some cases, the defects affecting the teeth, eye and ear can be either individual or combined. When these conditions are combined with eye coloboma, the condition is also known as oculo-otodental syndrome. The first known case of otodental syndrome was found in Hungary in a mother and her son by Denes and Csiba in 1969. Prevalence is less than 1 out of every 1 million individuals. The cause of otodental syndrome is considered to be genetic. It is an autosomal dominant inheritance and is variable in its expressivity. Haploinsufficiency in the fibroblast growth factor 3 (FGF3) gene (11q13) has been reported in patients with otodental syndrome and is thought to cause the phenotype. Both males and females are equally affected. Individuals diagnosed with otodental syndrome can be of any age; age is not a relevant factor. Currently there are no specific genetic treatments for otodental syndrome. Dental and orthodontic management are the recommended course of action.

Hereditary gingival fibromatosis (HGF), also known as idiopathic gingival hyperplasia, is a rare condition of gingival overgrowth. HGF is characterized as a benign, slowly progressive, nonhemorrhagic, fibrous enlargement of keratinized gingiva. It can cover teeth in various degrees, and can lead to aesthetic disfigurement. Fibrous enlargement is most common in areas of maxillary and mandibular tissues of both arches in the mouth. Phenotype and genotype frequency of HGF is 1:175,000 where males and females are equally affected but the cause is not entirely known. It mainly exists as an isolated abnormality but can also be associated with a multi-system syndrome.

Tooth ankylosis refers to a fusion between a tooth and underlying bony support tissues. In some species, this is a normal process that occurs during the formation or maintenance of the dentition. By contrast, in humans tooth ankylosis is pathological, whereby a fusion between alveolar bone and the cementum of a tooth occurs.

KBG syndrome is a rare genetic disease that is the result of a mutation in the ANKRD11 gene at location 16q24.3. Only about a hundred known cases have been reported, although it is expected to be under-reported.

References

  1. ↑ "Microdontia - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2020-12-17.
  2. 1 2 3 "Understanding Macrodontia: What It Is And How To Treat It". www.colgate.com. Retrieved 2020-12-16.
  3. ↑ "Making Bigger Teeth Smaller | East Valley Dental Professionals". www.evdp.net. Retrieved 2020-12-16.
  4. 1 2 3 Bello, Manuel O.; Garla, Vishnu V. (2020), "Gigantism And Acromegaly", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   30855849 , retrieved 2020-12-16
  5. ↑ Morel Swols, Dayna; Foster, Joseph; Tekin, Mustafa (2017-12-19). "KBG syndrome". Orphanet Journal of Rare Diseases. 12 (1): 183. doi: 10.1186/s13023-017-0736-8 . ISSN   1750-1172. PMC   5735576 . PMID   29258554.
  6. 1 2 3 Sirmaci, Asli; Spiliopoulos, Michail; Brancati, Francesco; Powell, Eric; Duman, Duygu; Abrams, Alex; Bademci, Guney; Agolini, Emanuele; Guo, Shengru; Konuk, Berrin; Kavaz, Asli (2011-08-12). "Mutations in ANKRD11 Cause KBG Syndrome, Characterized by Intellectual Disability, Skeletal Malformations, and Macrodontia". The American Journal of Human Genetics. 89 (2): 289–294. doi:10.1016/j.ajhg.2011.06.007. ISSN   0002-9297. PMC   3155157 . PMID   21782149.
  7. 1 2 MusWellHillSmile. "What you need to know about macrodontia". muswellhillsmile.co.uk. Retrieved 2020-12-17.
  8. 1 2 3 4 5 6 Firetto, Maria Cristina; Abbinante, Antonella; Barbato, Ersilia; Bellomi, Massimo; Biondetti, Pietro; Borghesi, Andrea; Bossu’, Maurizio; Cascone, Piero; Corbella, Daniela; Di Candido, Vincenzo; Diotallevi, Paolo (2019-09-01). "National guidelines for dental diagnostic imaging in the developmental age". La Radiologia Medica. 124 (9): 887–916. doi: 10.1007/s11547-019-01038-4 . ISSN   1826-6983. PMID   31055724.
  9. ↑ Mrinalini, Mahajan; Chetan, Chawla (2015-05-01). "True generalized macrodontia in a case of Rabson–Mendenhall syndrome". Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology. 27 (3): 357–360. doi:10.1016/j.ajoms.2014.04.006. ISSN   2212-5558.
  10. 1 2 "All you need to know about macrodontia". dentagama.com. Retrieved 2017-03-30.
  11. ↑ Wimalarathna, AAAK. "Macrodontia: Is it a clinical challenge?".
  12. 1 2 Canoglu, Ebru; Canoglu, Harun; Aktas, Alper; Cehreli, Zafer C. (June 2012). "Isolated bilateral macrodontia of mandibular second premolars: A case report". European Journal of Dentistry. 6 (3): 330–334. doi:10.1055/s-0039-1698969. ISSN   1305-7456. PMC   3420842 . PMID   22904663.
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