It is phenotypically difficult to diagnose between TDO and Amelogenesis imperfecta of the hypomaturation-hypoplasia type with taurodontism (AIHHT) as they are very closely linked phenotypically during adulthood, and the only distinguishing characteristic is found during genetic analysis by Polymerase Chain Reaction (PCR) amplification. This type of test in diagnosis of TDO is only used during research or if there is a concern of genetic issue to a particular individual whose family member has been diagnosed with TDO.

TDO is a genetic based disorder it is diagnosed based on radiographic imaging, physical characteristics of the disease, and genetic testing if necessary. PCR amplification is used to check for normal and deletion allele, found in the 141 base pair allele. A four base pair deletion in exon 3 is also noted in patients with TDO; deletion in two transcription factor genes DLX-3 and DLX-7 gene (distal-less gene) that occurs by a frameshift mutation, makes this gene shorter than its normal length and non-functional. Radiographs such as cephalometric analysis or panoramic radiograph are used to detect skeletal abnormalities in TDO cases; these radiographs along with the phenotypic effects of the disease are often enough evidence for proper diagnosis. In TDO, radiologic imaging almost always shows evidence of hardening of bone tissue (sclerosis), lesions on the bone structures surrounding the teeth due to decay or trauma, or hard tissue mass. The radiographic testing is non-invasive, and involves the patient to be able to sit or stand in front of the radiographic device with their mouth closed and lips relaxed for approximately one minute. Oral abnormalities are diagnosed by a visual dental examination. A normal oral evaluation would show no signs of broken or fractured teeth, attrition of tooth enamel, no spacing between teeth, no soft tissue mass or sign of dental abscess, and a bite relationship where the mandibular (bottom) teeth interdigitate within a normal plane of 1-2mm behind and underneath the maxillary (top) teeth.

AI can be classified according to their clinical appearances:

- Type 1 - Hypoplastic

Enamel of abnormal thickness due to malfunction in enamel matrix formation. Enamel is very thin but hard & translucent, and may have random pits & grooves. Condition is of autosomal dominant, autosomal recessive, or x-linked pattern. Enamel differs in appearance from dentine radiographically as normal functional enamel.

- Type 2 - Hypomaturation

Enamel has sound thickness, with a pitted appearance. It is less hard compared to normal enamel, and are prone to rapid wear, although not as intense as Type 3 AI. Condition is of autosomal dominant, autosomal recessive, or x-linked pattern. Enamel appears to be comparable to dentine in its radiodensity on radiograpshs.

- Type 3 - Hypocalcified

Enamel defect due to malfunction of enamel calcification, therefore enamel is of normal thickness but is extremely brittle, with an opaque/chalky presentation. Teeth are prone to staining and rapid wear, exposing dentine. Condition is of autosomal dominant and autosomal recessive pattern. Enamel appears less radioopaque compared to dentine on radiographs.

- Type 4: Hypomature hypoplastic enamel with taurodontism

Enamel has a variation in appearance, with mixed features from Type 1 and Type 2 AI. All Type 4 AI has taurodontism in common. Condition is of autosomal dominant pattern.

Other common features may include an anterior open bite, taurodontism, sensitivity of teeth.

Differential diagnosis would include dental fluorosis, molar-incisor hypomineralization, chronological disorders of tooth development.

Preventive and restorative dental care is very important as well as considerations for esthetic issues since the crown are yellow from exposure of dentin due to enamel loss. The main objectives of treatment is pain relief, preserving patient's remaining dentition, and to treat and preserve the patient's occlusal vertical height.

Many factors are to be considered to decide on treatment options such as the classification and severity of AI, the patient's social history, clinical findings etc. There are many classifications of AI but the general management of this condition is similar.

Full-coverage crowns are sometimes being used to compensate for the abraded enamel in adults, tackling the sensitivity the patient experiences. Usually stainless steel crowns are used in children which may be replaced by porcelain once they reach adulthood. These aid with maintaining occlusal vertical dimension.

Aesthetics may be addressed via placement of composite or porcelain veneers, depending on patient factors eg age. If the patient has primary or mixed dentition, lab-made composite veneers may be provided temporarily, to be replaced by permanent porcelain veneers once the patient has stabilized permanent dentition. The patient's oral hygiene and diet should be controlled as well as they play a factor in the success of retaining future restorations.

In the worst-case scenario, the teeth may have to be extracted and implants or dentures are required. Loss of nerves in the affected teeth may occur.

Teeth affected by macrodontia are either contoured, aligned or extracted. Contouring involves shaving the tooth down to change shape and size. However, the result is minimal change as this could be dangerous for the dentin and dental pulp. Aligning involves the use of braces to straighten, align, and make space for larger teeth to grow. When extracted, they are replaced with an implant or bridge. This is done in cases in which the patient suffers from pain that cannot be treated by other methods.

Taurodontism is a condition found in the molar teeth of humans whereby the body of the tooth and pulp chamber is enlarged vertically at the expense of the roots. As a result, the floor of the pulp and the furcation of the tooth is moved apically down the root. The underlying mechanism

of taurodontism is the failure or late invagination of Hertwig's epithelial root sheath, which is responsible for root formation and shaping causing an apical shift of the root furcation.

The constriction at the amelocemental junction is usually reduced or absent. Taurodontism is most commonly found in permanent dentition although the term is traditionally applied to molar teeth.

In some cases taurodontism seems to follow an autosomal dominant type of inheritance.

Taurodontism is found in association with amelogenesis imperfecta, ectodermal dysplasia and tricho-dento-osseous syndrome.

The term means "bull like" teeth derived from similarity of these teeth to those of ungulate or cud-chewing animals.

According to Shaw these can be classified as hypotaurodont, hypertaurodont and mesotaurodont.

According to Mangion taurodontism may be:

- A (mentally retarded) character

- A primitive pattern

- Mendelian recessive character

- Atavistic feature

- A mutation

It has also been reported in Klinefelter's syndrome, XXYY and Down's syndrome .

The teeth involved are invariably molars, sometimes single and at the other times multiple teeth may be involved. The teeth themselves may look normal and do not have any particular anatomical character on clinical examination.

On a dental radiograph, the involved tooth looks rectangular in shape without apical taper. The pulp chamber is extremely large and the furcations may be only a few millimeters long at times.

Macrodontia (or megadontia or megalodontia) is a type of localized gigantism in which teeth are larger than normal for the particular type(s) of teeth involved. The three types of macrodontia are true generalized macrodontia, relative generalized macrodontia, and macrodontia of a single tooth. True generalized macrodontia is rare. Macrodontia of a single tooth is more common. Some kind of macrodontia in the permanent dentition occurs in 1.1% of the total population. It should not be confused with taurodontism (bull teeth), fusion (double tooth) or the jaws being relatively small, giving the appearance of macrodontia.

Diagnosis of otodental syndrome was established using clinical, histopathological and audiometric methodologies. In normal individuals, by the age of 2-3, radiograph images should depict any signs of premolar development. A formal diagnosis of no premolar growth can be done by age 6 in order to check for signs of otodental syndrome. Sensorineural hearing loss can be another measure for proper diagnosis as well as checking for ocular coloboma. The latter is usually noticed at an around birth.

Molecular genetic testing can aid in the diagnosis of the affected individual, which would determine if there are any abnormalities in the FGF3 gene (11q13) or the FADD gene (11q13.3). Additional tests that can help diagnose otodental syndrome are ear infection tests, hearing tests, oral examination, and eye examinations to check for the specific phenotypic associations. Due to the rarity of otodental syndrome, most symptoms are looked at on an individual basis unless multiple symptoms are all apparent at once.

There is potential for differential diagnosis due to similarities in symptoms. Other diseases that share common symptoms are chondroectodermal dysplasia, achondrodysplasia, and osteopetrosis

The condition is of anthropological importance as it was seen in Neanderthals.

The trait ""is common among extant New World monkeys, apes, and fossil hominins"".

Currently there are no open research studies for otodental syndrome. Due to the rarity of this disease, current research is very limited.

The most recent research has involved case studies of the affected individuals and/or families, all of which show the specific phenotypic symptoms of otodental syndrome. Investigations on the effects of FGF3 and FADD have also been performed. These studies have shown successes in supporting previous studies that mutations to FGF3 and neighboring genes may cause the associated phenotypic abnormalities. According to recent studies involving zebrafish embryos, there is also support in that the FADD gene contributed to ocular coloboma symptoms as well.

Future research studies are required in order to better grasp the specific relationship between the gene involved and its effect on various tissues and organs such as teeth, eyes, and ear. Little is known and there is still much to be determined.

Ackerman syndrome is a familial syndrome of fused molar roots with a single canal (taurodontism), hypotrichosis, full upper lip without a cupid’s bow, thickened and wide philtrum, and occasional juvenile glaucoma.

It was described by James L. Ackerman, A. Leon Ackerman, and A. Bernard Ackerman.

It can also refer to interstitial granulomatous dermatitis.

Diagnosis of 48, XXXY is usually done by a standard karyotype. A karyotype is a chromosomal analysis in which a full set of chromosomes can be seen for an individual. The presence of the additional 2 X chromosomes on the karyotype are indicative of XXXY syndrome.

Another way to diagnosis 48, XXXY is by chromosomal microarray showing the presence of extra X chromosomes. Chromosomal microarray (CMA) is used to detect extra or missing chromosomal segments or whole chromosomes. CMA uses microchip-based testing to analyze many pieces of DNA. Males with 48, XXXY are diagnosed anywhere from before birth to adulthood as a result of the range in the severity of symptoms. The age range at diagnosis is likely due to the fact that XXXY is a rare syndrome, and does not cause as extreme phenotypes as other variants of Klinefelter syndrome (such as XXXXY).

Diagnostic testing could also be done via blood samples. Elevated levels of follicle stimulating hormone, luteinizing hormone, and low levels of testosterone can be indicative of this syndrome.

As the syndrome is due to a chromosomal non-disjunction event, the recurrence risk is not high compared to the general population. There has been no evidence found that indicates non-disjunction occurs more often in a particular family.