Examining Crossbites and Jaw Alignment

Examining Crossbites and Jaw Alignment

Types of Malocclusions: Overview of common types such as overbite, underbite, and crossbite in pediatric patients.

Crossbites are a common orthodontic issue that can significantly influence jaw development and overall oral health. These malocclusions occur when one or more teeth in the upper arch fit inside the corresponding teeth in the lower arch, reversing the normal bite pattern. Understanding the different types of crossbites and their impact on jaw development is crucial for effective diagnosis and treatment.


There are two primary types of crossbites: anterior and posterior. Braces help correct misaligned teeth in children Early orthodontic intervention jaw. An anterior crossbite involves the front teeth, where one or more upper incisors sit behind the lower incisors. This type of crossbite can resemble an underbite and often leads to concerns about the aesthetic appearance of the smile. More importantly, if left untreated, anterior crossbites can cause the jaw to grow asymmetrically, leading to potential difficulties with chewing and speech.


On the other hand, a posterior crossbite affects the back teeth, where the upper molars or premolars sit inside the lower ones. This condition is often linked to a narrow upper jaw, which can restrict proper jaw movement and lead to uneven wear on the teeth. Posterior crossbites can also result in a shift of the lower jaw to one side, causing facial asymmetry and potential temporomandibular joint (TMJ) disorders.


The impact of crossbites on jaw development cannot be overstated. During childhood and adolescence, the jaw is still growing, and any misalignment can influence its development trajectory. Crossbites can lead to compensatory growth patterns, where the jaw attempts to adapt to the misaligned bite. This can result in a range of issues, from crowded or misaligned teeth to more severe skeletal discrepancies that may require orthognathic surgery later in life.


Early intervention is key to mitigating the effects of crossbites on jaw development. Orthodontists often recommend treatment as soon as a crossbite is detected, typically using appliances like palatal expanders for posterior crossbites or braces for anterior crossbites. These interventions aim to guide the jaw into proper alignment, allowing for more harmonious growth and development.


In conclusion, crossbites are not just cosmetic concerns; they have a profound impact on jaw development and overall oral health. By understanding the types of crossbites and their potential effects, orthodontists can implement timely and effective treatments to ensure optimal jaw growth and function. This proactive approach not only enhances the appearance of the smile but also supports long-term oral health and well-being.

Early detection and diagnosis of crossbites in pediatric patients is a crucial aspect of pediatric dentistry and orthodontics, as it plays a significant role in the overall development and alignment of a child's jaw. Crossbites, which occur when the upper teeth fit inside the lower teeth, can lead to a variety of issues if not addressed in a timely manner. By examining crossbites and jaw alignment early on, dental professionals can help prevent potential complications and ensure proper oral health and function.


One of the primary reasons for early detection of crossbites is the malleability of a child's jaw during their developmental years. The jaw and teeth are more responsive to orthodontic treatment during childhood, making it an ideal time to correct any misalignments. By identifying a crossbite early, orthodontists can employ various interventions, such as palatal expanders or braces, to guide the jaw and teeth into their proper positions. This not only helps to correct the crossbite but also promotes healthy jaw growth and development.


Moreover, early diagnosis of crossbites can help prevent the development of secondary issues that may arise from an untreated misalignment. For instance, a crossbite can lead to uneven wear on the teeth, which may result in premature tooth loss or the need for restorative dental work later in life. Additionally, a misaligned jaw can cause difficulties with biting and chewing, potentially leading to digestive problems or temporomandibular joint (TMJ) disorders. By addressing crossbites early, these potential complications can be minimized or avoided altogether.


Another important aspect of early detection and diagnosis of crossbites is the impact on a child's self-esteem and overall well-being. Children with noticeable dental misalignments may experience self-consciousness or teasing from their peers, which can negatively affect their confidence and social interactions. By correcting a crossbite early, orthodontists can help improve a child's smile and boost their self-esteem, contributing to their overall emotional and psychological well-being.


To ensure early detection of crossbites, it is essential for parents to schedule regular dental check-ups for their children. Pediatric dentists and orthodontists are trained to identify potential misalignments and can monitor a child's jaw development over time. If a crossbite is detected, the dental professional can discuss the available treatment options and develop a personalized plan to address the issue.


In conclusion, early detection and diagnosis of crossbites in pediatric patients is vital for promoting proper jaw alignment, preventing secondary complications, and supporting a child's overall health and well-being. By working closely with dental professionals and maintaining regular check-ups, parents can help ensure that their child's oral development is on the right track, setting the foundation for a lifetime of healthy smiles.

Early Detection and Diagnosis: The importance of regular dental check-ups for identifying malocclusions in children.

When it comes to the dental health of children, addressing issues such as crossbites early on can significantly impact their oral development and overall well-being. Crossbites, a misalignment where the upper teeth fit inside the lower teeth, can lead to various complications if not treated promptly. Fortunately, orthodontic treatment offers several effective options for correcting crossbites in kids, ensuring a healthier smile and improved jaw alignment.


One of the primary orthodontic treatments for correcting crossbites in children is the use of palatal expanders. These devices are particularly effective for younger patients whose jawbones are still growing. A palatal expander gently widens the upper jaw, creating more space for the teeth to align properly. This non-invasive approach can often correct a crossbite without the need for more extensive treatments later on.


Braces are another common and effective treatment option for crossbites. Traditional metal braces or more aesthetically pleasing ceramic braces can be used to gradually move the teeth into their correct positions. For children with crossbites, braces can realign both the teeth and the jaw, improving the bite and preventing further misalignment. The duration of treatment with braces varies depending on the severity of the crossbite, but it typically ranges from one to two years.


In some cases, particularly when the crossbite is more severe or if the child is older, orthodontists may recommend the use of headgear. Headgear works by applying gentle pressure to the upper jaw, helping to guide it into the correct position. While it may seem daunting, modern headgear designs are more comfortable and less conspicuous than in the past, making it a viable option for correcting crossbites in kids.


For children with mild to moderate crossbites, clear aligners such as Invisalign may be a suitable alternative to traditional braces. These custom-made, removable trays gradually shift the teeth into alignment. Clear aligners are particularly appealing to older children and teenagers who may be self-conscious about wearing braces. However, compliance is crucial, as the aligners must be worn for the recommended 20-22 hours per day to be effective.


Early intervention is key when it comes to correcting crossbites in children. By addressing the issue during the developmental years, orthodontists can guide the growth of the jaw and teeth, preventing more serious complications down the line. Regular dental check-ups and consultations with an orthodontist can help identify crossbites early, allowing for timely and effective treatment.


In conclusion, orthodontic treatment offers a range of options for correcting crossbites in kids, from palatal expanders and braces to headgear and clear aligners. Each treatment plan is tailored to the individual needs of the child, taking into account the severity of the crossbite and the stage of their dental development. By seeking early intervention and following through with the recommended treatment, parents can help their children achieve a healthier, more aligned smile that will benefit them for years to come.

Orthodontic Treatment Options for Kids: Discussing braces, aligners, and other corrective measures suitable for young patients.

The Role of Orthodontic Appliances in Jaw Alignment for Children: Examining Crossbites and Jaw Alignment


When it comes to the development of a child's oral health, the role of orthodontic appliances cannot be overstated, particularly in the context of addressing crossbites and ensuring proper jaw alignment. As a parent, understanding how these tools can benefit your child is crucial for making informed decisions about their dental care.


Crossbites, a common orthodontic issue among children, occur when the upper teeth fit inside the lower teeth. This misalignment can lead to a range of problems, from difficulty chewing and speaking to more severe issues like jaw pain and uneven wear on the teeth. Fortunately, orthodontic appliances offer a solution to these challenges.


One of the primary tools used in correcting crossbites and aligning jaws in children is the palatal expander. This device, typically used in younger patients whose jaws are still growing, works by gradually widening the upper jaw. By doing so, it creates more space for the teeth and helps to correct the crossbite. The process is usually slow and steady, with the expander being adjusted incrementally over several months.


Another common appliance is the headgear, which applies pressure to the upper teeth and jaw to guide their growth. While it may seem daunting, headgear can be highly effective in correcting severe crossbites and promoting proper jaw alignment. It's important for parents to work closely with their orthodontist to ensure the headgear is worn correctly and consistently.


Braces, perhaps the most well-known orthodontic appliance, also play a significant role in addressing crossbites and jaw alignment issues. By applying gentle, continuous pressure to the teeth, braces can gradually move them into their correct positions, helping to resolve crossbites and improve overall jaw alignment.


The key to successful treatment with orthodontic appliances lies in early intervention. The American Association of Orthodontists recommends that children have their first orthodontic evaluation by age 7. At this stage, many jaw alignment issues can be identified and addressed before they become more severe and harder to correct.


It's also important to recognize that the use of orthodontic appliances is not just about aesthetics. While a straight smile is certainly a confidence booster for children, the primary goal of these devices is to promote long-term oral health. By correcting crossbites and ensuring proper jaw alignment, orthodontic appliances can help prevent a range of issues, from TMJ disorders to difficulty biting and chewing.


In conclusion, orthodontic appliances play a vital role in addressing crossbites and promoting proper jaw alignment in children. From palatal expanders and headgear to braces, these tools offer effective solutions to common orthodontic issues. By working closely with an experienced orthodontist and embracing early intervention, parents can help ensure their child's oral health and development are on the right track.

The Role of Parents in Orthodontic Care: How parents can support their child's orthodontic treatment and encourage good oral habits.

Early orthodontic intervention for crossbites offers significant long-term benefits, playing a crucial role in ensuring proper jaw alignment and overall oral health. Crossbites, a type of malocclusion where one or more teeth are misaligned, can lead to a variety of issues if left untreated, including jaw asymmetry, uneven wear of teeth, and even difficulties with chewing and speaking.


One of the primary advantages of addressing crossbites early is the prevention of more severe skeletal discrepancies as the child grows. By intervening early, orthodontists can guide the growth of the jaw in a more favorable direction, often preventing the need for more invasive treatments later in life. This can be particularly beneficial during the mixed dentition stage, when both baby and permanent teeth are present, as the jaw is still developing and more malleable.


Moreover, early correction of crossbites can enhance facial aesthetics and improve a child's self-esteem. Children who undergo timely orthodontic treatment often experience a boost in confidence, as they are less self-conscious about their smile. This psychological benefit should not be underestimated, as it can have a lasting impact on a child's social interactions and overall well-being.


Another long-term benefit is the reduction in the risk of temporomandibular joint (TMJ) disorders. Crossbites can contribute to improper jaw function, which may lead to TMJ issues such as pain, clicking, and limited jaw movement. By correcting the crossbite early, orthodontists can help mitigate these risks, promoting better jaw function and comfort.


In addition, early intervention can lead to more stable and predictable orthodontic outcomes. Addressing crossbites at a younger age can simplify future orthodontic treatments, potentially reducing the duration and complexity of braces or aligners needed later on. This not only saves time and money but also ensures a more harmonious alignment of teeth and jaws in the long run.


In conclusion, the long-term benefits of early orthodontic intervention for crossbites are manifold. From preventing skeletal discrepancies and enhancing facial aesthetics to reducing the risk of TMJ disorders and simplifying future treatments, early intervention sets the stage for a healthier, more aligned smile. Parents and caregivers should be aware of these benefits and consider early orthodontic consultation to ensure the best possible outcomes for their child's oral health and development.

Long-term Benefits of Early Orthodontic Intervention: How treating malocclusions in childhood can prevent more serious issues in adulthood.

In the field of orthodontics, crossbites represent a significant challenge, particularly in young patients where early intervention can dramatically alter the course of jaw development and overall dental health. This essay delves into several case studies that showcase successful treatments of crossbites, offering insights into the effectiveness of various orthodontic strategies.


One compelling case involved a seven-year-old patient presenting with a unilateral posterior crossbite. This condition not only affected the patient's bite alignment but also contributed to an asymmetrical jaw development. The orthodontist opted for a palatal expander, a device that gradually widens the upper jaw. Over the course of six months, regular adjustments led to a successful correction of the crossbite. Post-treatment, the patient's jaw alignment was markedly improved, and the risk of further complications, such as temporomandibular joint disorder, was significantly reduced.


Another case study focused on a nine-year-old with a bilateral anterior crossbite, a condition where the upper front teeth sit behind the lower front teeth. This not only affects the aesthetics of the smile but can also lead to issues with jaw growth. The treatment plan included the use of a fixed orthodontic appliance to gently move the teeth into the correct position. After a year of treatment, the crossbite was corrected, and the patient's smile and bite function were restored to normal.


These case studies underscore the importance of early detection and intervention in treating crossbites. Young patients benefit immensely from treatments that address jaw alignment issues before they exacerbate into more complex conditions. The success of these treatments hinges on a tailored approach, considering the unique anatomical and developmental needs of each patient.


In conclusion, the successful treatment of crossbites in young patients not only enhances their immediate dental health but also sets a foundation for lifelong oral wellness. Orthodontists play a crucial role in these transformative journeys, employing a range of effective tools and techniques to ensure optimal outcomes. These case studies serve as a testament to the possibilities that lie in early orthodontic intervention, offering hope and improved quality of life for young patients grappling with crossbites.

 

Tooth
A chimpanzee displaying his teeth
Details
Identifiers
Latin dens
MeSH D014070
FMA 12516
Anatomical terminology
[edit on Wikidata]

A tooth (pl.: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tearing food, for defensive purposes, to intimidate other animals often including their own, or to carry prey or their young. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness that originate from the outermost embryonic germ layer, the ectoderm.

The general structure of teeth is similar across the vertebrates, although there is considerable variation in their form and position. The teeth of mammals have deep roots, and this pattern is also found in some fish, and in crocodilians. In most teleost fish, however, the teeth are attached to the outer surface of the bone, while in lizards they are attached to the inner surface of the jaw by one side. In cartilaginous fish, such as sharks, the teeth are attached by tough ligaments to the hoops of cartilage that form the jaw.[1]

Monophyodonts are animals that develop only one set of teeth, while diphyodonts grow an early set of deciduous teeth and a later set of permanent or "adult" teeth. Polyphyodonts grow many sets of teeth. For example, sharks, grow a new set of teeth every two weeks to replace worn teeth. Most extant mammals including humans are diphyodonts, but there are exceptions including elephants, kangaroos, and manatees, all of which are polyphyodonts.

Rodent incisors grow and wear away continually through gnawing, which helps maintain relatively constant length. The industry of the beaver is due in part to this qualification. Some rodents, such as voles and guinea pigs (but not mice), as well as lagomorpha (rabbits, hares and pikas), have continuously growing molars in addition to incisors.[2][3] Also, tusks (in tusked mammals) grow almost throughout life.[4]

Teeth are not always attached to the jaw, as they are in mammals. In many reptiles and fish, teeth are attached to the palate or to the floor of the mouth, forming additional rows inside those on the jaws proper. Some teleosts even have teeth in the pharynx. While not true teeth in the usual sense, the dermal denticles of sharks are almost identical in structure and are likely to have the same evolutionary origin. Indeed, teeth appear to have first evolved in sharks, and are not found in the more primitive jawless fish – while lampreys do have tooth-like structures on the tongue, these are in fact, composed of keratin, not of dentine or enamel, and bear no relationship to true teeth.[1] Though "modern" teeth-like structures with dentine and enamel have been found in late conodonts, they are now supposed to have evolved independently of later vertebrates' teeth.[5][6]

Living amphibians typically have small teeth, or none at all, since they commonly feed only on soft foods. In reptiles, teeth are generally simple and conical in shape, although there is some variation between species, most notably the venom-injecting fangs of snakes. The pattern of incisors, canines, premolars and molars is found only in mammals, and to varying extents, in their evolutionary ancestors. The numbers of these types of teeth vary greatly between species; zoologists use a standardised dental formula to describe the precise pattern in any given group.[1]

Etymology

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The word tooth comes from Proto-Germanic *tanþs, derived from the Proto-Indo-European *h₁dent-, which was composed of the root *h₁ed- 'to eat' plus the active participle suffix *-nt, therefore literally meaning 'that which eats'.[7]

The irregular plural form teeth is the result of Germanic umlaut whereby vowels immediately preceding a high vocalic in the following syllable were raised. As the nominative plural ending of the Proto-Germanic consonant stems (to which *tanþs belonged) was *-iz, the root vowel in the plural form *tanþiz (changed by this point to *tÄ…Ì„þi via unrelated phonological processes) was raised to /œÃƒâ€¹Ã‚/, and later unrounded to /eː/, resulting in the tōþ/tÄ“þ alternation attested from Old English. Cf. also Old English bōc/bēċ 'book/books' and 'mÅ«s/mȳs' 'mouse/mice', from Proto-Germanic *bōks/bōkiz and *mÅ«s/mÅ«siz respectively.

Cognate with Latin dÄ“ns, Greek á½€δούς (odous), and Sanskrit dát.

Origin

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Teeth are assumed to have evolved either from ectoderm denticles (scales, much like those on the skin of sharks) that folded and integrated into the mouth (called the "outside–in" theory), or from endoderm pharyngeal teeth (primarily formed in the pharynx of jawless vertebrates) (the "inside–out" theory). In addition, there is another theory stating that neural crest gene regulatory network, and neural crest-derived ectomesenchyme are the key to generate teeth (with any epithelium, either ectoderm or endoderm).[4][8]

The genes governing tooth development in mammals are homologous to those involved in the development of fish scales.[9] Study of a tooth plate of a fossil of the extinct fish Romundina stellina showed that the teeth and scales were made of the same tissues, also found in mammal teeth, lending support to the theory that teeth evolved as a modification of scales.[10]

Mammals

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Teeth are among the most distinctive (and long-lasting) features of mammal species. Paleontologists use teeth to identify fossil species and determine their relationships. The shape of the animal's teeth are related to its diet. For example, plant matter is hard to digest, so herbivores have many molars for chewing and grinding. Carnivores, on the other hand, have canine teeth to kill prey and to tear meat.

Mammals, in general, are diphyodont, meaning that they develop two sets of teeth. In humans, the first set (the "baby", "milk", "primary" or "deciduous" set) normally starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as neonatal teeth. Normal tooth eruption at about six months is known as teething and can be painful. Kangaroos, elephants, and manatees are unusual among mammals because they are polyphyodonts.

Aardvark

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In aardvarks, teeth lack enamel and have many pulp tubules, hence the name of the order Tubulidentata.[11]

Canines

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In dogs, the teeth are less likely than humans to form dental cavities because of the very high pH of dog saliva, which prevents enamel from demineralizing.[12] Sometimes called cuspids, these teeth are shaped like points (cusps) and are used for tearing and grasping food.[13]

Cetaceans

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Like human teeth, whale teeth have polyp-like protrusions located on the root surface of the tooth. These polyps are made of cementum in both species, but in human teeth, the protrusions are located on the outside of the root, while in whales the nodule is located on the inside of the pulp chamber. While the roots of human teeth are made of cementum on the outer surface, whales have cementum on the entire surface of the tooth with a very small layer of enamel at the tip. This small enamel layer is only seen in older whales where the cementum has been worn away to show the underlying enamel.[14]

The toothed whale is a parvorder of the cetaceans characterized by having teeth. The teeth differ considerably among the species. They may be numerous, with some dolphins bearing over 100 teeth in their jaws. On the other hand, the narwhals have a giant unicorn-like tusk, which is a tooth containing millions of sensory pathways and used for sensing during feeding, navigation, and mating. It is the most neurologically complex tooth known. Beaked whales are almost toothless, with only bizarre teeth found in males. These teeth may be used for feeding but also for demonstrating aggression and showmanship.

Primates

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In humans (and most other primates), there are usually 20 primary (also "baby" or "milk") teeth, and later up to 32 permanent teeth. Four of these 32 may be third molars or wisdom teeth, although these are not present in all adults, and may be removed surgically later in life.[15]

Among primary teeth, 10 of them are usually found in the maxilla (i.e. upper jaw) and the other 10 in the mandible (i.e. lower jaw). Among permanent teeth, 16 are found in the maxilla and the other 16 in the mandible. Most of the teeth have uniquely distinguishing features.

Horse

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An adult horse has between 36 and 44 teeth. The enamel and dentin layers of horse teeth are intertwined.[16] All horses have 12 premolars, 12 molars, and 12 incisors.[17] Generally, all male equines also have four canine teeth (called tushes) between the molars and incisors. However, few female horses (less than 28%) have canines, and those that do usually have only one or two, which many times are only partially erupted.[18] A few horses have one to four wolf teeth, which are vestigial premolars, with most of those having only one or two. They are equally common in male and female horses and much more likely to be on the upper jaw. If present these can cause problems as they can interfere with the horse's bit contact. Therefore, wolf teeth are commonly removed.[17]

Horse teeth can be used to estimate the animal's age. Between birth and five years, age can be closely estimated by observing the eruption pattern on milk teeth and then permanent teeth. By age five, all permanent teeth have usually erupted. The horse is then said to have a "full" mouth. After the age of five, age can only be conjectured by studying the wear patterns on the incisors, shape, the angle at which the incisors meet, and other factors. The wear of teeth may also be affected by diet, natural abnormalities, and cribbing. Two horses of the same age may have different wear patterns.

A horse's incisors, premolars, and molars, once fully developed, continue to erupt as the grinding surface is worn down through chewing. A young adult horse will have teeth, which are 110–130 mm (4.5–5 inches) long, with the majority of the crown remaining below the gumline in the dental socket. The rest of the tooth will slowly emerge from the jaw, erupting about 3 mm (18 in) each year, as the horse ages. When the animal reaches old age, the crowns of the teeth are very short and the teeth are often lost altogether. Very old horses, if lacking molars, may need to have their fodder ground up and soaked in water to create a soft mush for them to eat in order to obtain adequate nutrition.

Proboscideans

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Section through the ivory tusk of a mammoth

Elephants' tusks are specialized incisors for digging food up and fighting. Some elephant teeth are similar to those in manatees, and elephants are believed to have undergone an aquatic phase in their evolution.

At birth, elephants have a total of 28 molar plate-like grinding teeth not including the tusks. These are organized into four sets of seven successively larger teeth which the elephant will slowly wear through during its lifetime of chewing rough plant material. Only four teeth are used for chewing at a given time, and as each tooth wears out, another tooth moves forward to take its place in a process similar to a conveyor belt. The last and largest of these teeth usually becomes exposed when the animal is around 40 years of age, and will often last for an additional 20 years. When the last of these teeth has fallen out, regardless of the elephant's age, the animal will no longer be able to chew food and will die of starvation.[19][20]

Rabbit

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Rabbits and other lagomorphs usually shed their deciduous teeth before (or very shortly after) their birth, and are usually born with their permanent teeth.[21] The teeth of rabbits complement their diet, which consists of a wide range of vegetation. Since many of the foods are abrasive enough to cause attrition, rabbit teeth grow continuously throughout life.[22] Rabbits have a total of six incisors, three upper premolars, three upper molars, two lower premolars, and two lower molars on each side. There are no canines. Dental formula is 2.0.3.31.0.2.3 = 28. Three to four millimeters of the tooth is worn away by incisors every week, whereas the cheek teeth require a month to wear away the same amount.[23]

The incisors and cheek teeth of rabbits are called aradicular hypsodont teeth. This is sometimes referred to as an elodent dentition. These teeth grow or erupt continuously. The growth or eruption is held in balance by dental abrasion from chewing a diet high in fiber.

Buccal view of top incisor from Rattus rattus. Top incisor outlined in yellow. Molars circled in blue.
Buccal view of the lower incisor from the right dentary of a Rattus rattus
Lingual view of the lower incisor from the right dentary of a Rattus rattus
Midsagittal view of top incisor from Rattus rattus. Top incisor outlined in yellow. Molars circled in blue.

Rodents

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Rodents have upper and lower hypselodont incisors that can continuously grow enamel throughout its life without having properly formed roots.[24] These teeth are also known as aradicular teeth, and unlike humans whose ameloblasts die after tooth development, rodents continually produce enamel, they must wear down their teeth by gnawing on various materials.[25] Enamel and dentin are produced by the enamel organ, and growth is dependent on the presence of stem cells, cellular amplification, and cellular maturation structures in the odontogenic region.[26] Rodent incisors are used for cutting wood, biting through the skin of fruit, or for defense. This allows for the rate of wear and tooth growth to be at equilibrium.[24] The microstructure of rodent incisor enamel has shown to be useful in studying the phylogeny and systematics of rodents because of its independent evolution from the other dental traits. The enamel on rodent incisors are composed of two layers: the inner portio interna (PI) with Hunter-Schreger bands (HSB) and an outer portio externa (PE) with radial enamel (RE).[27] It usually involves the differential regulation of the epithelial stem cell niche in the tooth of two rodent species, such as guinea pigs.[28][29]

Lingual view of top incisor from Rattus rattus. Top incisor outlined in yellow. Molars circled in blue.

The teeth have enamel on the outside and exposed dentin on the inside, so they self-sharpen during gnawing. On the other hand, continually growing molars are found in some rodent species, such as the sibling vole and the guinea pig.[28][29] There is variation in the dentition of the rodents, but generally, rodents lack canines and premolars, and have a space between their incisors and molars, called the diastema region.

Manatee

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Manatees are polyphyodont with mandibular molars developing separately from the jaw and are encased in a bony shell separated by soft tissue.[30][31]

Walrus

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Walrus tusks are canine teeth that grow continuously throughout life.[32]

Fish

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Teeth of a great white shark

Fish, such as sharks, may go through many teeth in their lifetime. The replacement of multiple teeth is known as polyphyodontia.

A class of prehistoric shark are called cladodonts for their strange forked teeth.

Unlike the continuous shedding of functional teeth seen in modern sharks,[33][34] the majority of stem chondrichthyan lineages retained all tooth generations developed throughout the life of the animal.[35] This replacement mechanism is exemplified by the tooth whorl-based dentitions of acanthodians,[36] which include the oldest known toothed vertebrate, Qianodus duplicis[37].

Amphibians

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All amphibians have pedicellate teeth, which are modified to be flexible due to connective tissue and uncalcified dentine that separates the crown from the base of the tooth.[38]

Most amphibians exhibit teeth that have a slight attachment to the jaw or acrodont teeth. Acrodont teeth exhibit limited connection to the dentary and have little enervation.[39] This is ideal for organisms who mostly use their teeth for grasping, but not for crushing and allows for rapid regeneration of teeth at a low energy cost. Teeth are usually lost in the course of feeding if the prey is struggling. Additionally, amphibians that undergo a metamorphosis develop bicuspid shaped teeth.[40]

Reptiles

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The teeth of reptiles are replaced constantly throughout their lives. Crocodilian juveniles replace teeth with larger ones at a rate as high as one new tooth per socket every month. Once mature, tooth replacement rates can slow to two years and even longer. Overall, crocodilians may use 3,000 teeth from birth to death. New teeth are created within old teeth.[41]

Birds

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A skull of Ichthyornis discovered in 2014 suggests that the beak of birds may have evolved from teeth to allow chicks to escape their shells earlier, and thus avoid predators and also to penetrate protective covers such as hard earth to access underlying food.[42][43]

Invertebrates

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The European medicinal leech has three jaws with numerous sharp teeth which function like little saws for incising a host.

True teeth are unique to vertebrates,[44] although many invertebrates have analogous structures often referred to as teeth. The organisms with the simplest genome bearing such tooth-like structures are perhaps the parasitic worms of the family Ancylostomatidae.[45] For example, the hookworm Necator americanus has two dorsal and two ventral cutting plates or teeth around the anterior margin of the buccal capsule. It also has a pair of subdorsal and a pair of subventral teeth located close to the rear.[46]

Historically, the European medicinal leech, another invertebrate parasite, has been used in medicine to remove blood from patients.[47] They have three jaws (tripartite) that resemble saws in both appearance and function, and on them are about 100 sharp teeth used to incise the host. The incision leaves a mark that is an inverted Y inside of a circle. After piercing the skin and injecting anticoagulants (hirudin) and anaesthetics, they suck out blood, consuming up to ten times their body weight in a single meal.[48]

In some species of Bryozoa, the first part of the stomach forms a muscular gizzard lined with chitinous teeth that crush armoured prey such as diatoms. Wave-like peristaltic contractions then move the food through the stomach for digestion.[49]

The limpet rasps algae from rocks using teeth with the strongest known tensile strength of any biological material.

Molluscs have a structure called a radula, which bears a ribbon of chitinous teeth. However, these teeth are histologically and developmentally different from vertebrate teeth and are unlikely to be homologous. For example, vertebrate teeth develop from a neural crest mesenchyme-derived dental papilla, and the neural crest is specific to vertebrates, as are tissues such as enamel.[44]

The radula is used by molluscs for feeding and is sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, typically used for scraping or cutting food before the food enters the oesophagus. The radula is unique to molluscs, and is found in every class of mollusc apart from bivalves.

Within the gastropods, the radula is used in feeding by both herbivorous and carnivorous snails and slugs. The arrangement of teeth (also known as denticles) on the radula ribbon varies considerably from one group to another as shown in the diagram on the left.

Predatory marine snails such as the Naticidae use the radula plus an acidic secretion to bore through the shell of other molluscs. Other predatory marine snails, such as the Conidae, use a specialized radula tooth as a poisoned harpoon. Predatory pulmonate land slugs, such as the ghost slug, use elongated razor-sharp teeth on the radula to seize and devour earthworms. Predatory cephalopods, such as squid, use the radula for cutting prey.

In most of the more ancient lineages of gastropods, the radula is used to graze by scraping diatoms and other microscopic algae off rock surfaces and other substrates. Limpets scrape algae from rocks using radula equipped with exceptionally hard rasping teeth.[50] These teeth have the strongest known tensile strength of any biological material, outperforming spider silk.[50] The mineral protein of the limpet teeth can withstand a tensile stress of 4.9 GPa, compared to 4 GPa of spider silk and 0.5 GPa of human teeth.[51]

 

Fossilization and taphonomy

[edit]

Because teeth are very resistant, often preserved when bones are not,[52] and reflect the diet of the host organism, they are very valuable to archaeologists and palaeontologists.[53] Early fish such as the thelodonts had scales composed of dentine and an enamel-like compound, suggesting that the origin of teeth was from scales which were retained in the mouth. Fish as early as the late Cambrian had dentine in their exoskeletons, which may have functioned in defense or for sensing their environments.[54] Dentine can be as hard as the rest of teeth and is composed of collagen fibres, reinforced with hydroxyapatite.[54]

Though teeth are very resistant, they also can be brittle and highly susceptible to cracking.[55] However, cracking of the tooth can be used as a diagnostic tool for predicting bite force. Additionally, enamel fractures can also give valuable insight into the diet and behaviour of archaeological and fossil samples.

Decalcification removes the enamel from teeth and leaves only the organic interior intact, which comprises dentine and cementine.[56] Enamel is quickly decalcified in acids,[57] perhaps by dissolution by plant acids or via diagenetic solutions, or in the stomachs of vertebrate predators.[56] Enamel can be lost by abrasion or spalling,[56] and is lost before dentine or bone are destroyed by the fossilisation process.[57] In such a case, the 'skeleton' of the teeth would consist of the dentine, with a hollow pulp cavity.[56] The organic part of dentine, conversely, is destroyed by alkalis.[57]

See also

[edit]
  • Animal tooth development
  • Dragon's teeth (mythology)

References

[edit]
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Sources

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  • Shoshani, Jeheskel (2002). "Tubulidentata". In Robertson, Sarah (ed.). Encyclopedia of Life Sciences. Vol. 18: Svedberg, Theodor to Two-hybrid and Related Systems. London, UK: Nature Publishing Group. ISBN 978-1-56159-274-6.
[edit]
  • Beach, Chandler B., ed. (1914). "Teeth" . The New Student's Reference Work . Chicago: F. E. Compton and Co.

 

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Redirect to:

  • Tooth decay
  • From a page move: This is a redirect from a page that has been moved (renamed). This page was kept as a redirect to avoid breaking links, both internal and external, that may have been made to the old page name.

Frequently Asked Questions

A crossbite is a misalignment where the upper teeth fit inside the lower teeth. Its a concern for kids because it can lead to jaw growth problems, uneven wear of teeth, and issues with chewing and speech if not corrected early.
Look for signs such as uneven wear on teeth, difficulty chewing, shifting of the jaw to one side when biting down, and facial asymmetry. A dentist or orthodontist can provide a professional assessment.
Its recommended to have your child evaluated by an orthodontist by age 7. Early intervention can prevent more severe issues later on.
Treatment options may include orthodontic appliances like palatal expanders, braces, or in severe cases, surgical intervention. The choice depends on the severity and the childs age.
The duration of treatment varies based on the severity of the misalignment and the chosen treatment method. Early intervention with appliances like expanders can be relatively quick, often completed within a few months, while braces might take 1-2 years.