Dental Anatomy

Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. (The function of teeth as they contact one another falls elsewhere, under dental occlusion.) Tooth formation begins before birth, and teeth’s eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment.

Usually, there are 20 primary (“baby”) teeth and 28 to 32 permanent teeth, the last four being third molars or “wisdom teeth”, each of which may or may not grow in. Among primary teeth, 10 usually are found in the maxilla (upper jaw) and the other 10 in the mandible (lower jaw). Among permanent teeth, 16 are found in the maxilla and the other 16 in the mandible. Most of the teeth have distinguishing features.

There are several different dental notation systems for associating information to a specific tooth. The three most commons systems are the FDI World Dental Federation notation, Universal numbering system (dental), and Palmer notation method. The FDI system is used worldwide, and the universal is used widely in the USA.

The universal numbering system uses a unique letter or number for each tooth. The uppercase letters A through T are used for primary teeth and the numbers 1 – 32 are used for permanent teeth. The tooth designated “1” is the right maxillary third molar and the count continues along the upper teeth to the left side. Then the count begins at the left mandibular third molar, designated number 17, and continues along the bottom teeth to the right side.

Alveolar Bone

As humans, we tend to put a lot of stress on our teeth. From eating to playing sports and chewing on anything from pencils to bubblegum. Luckily for us, each tooth is secured in place by the bones and tissues in our mouth.

Specifically, our teeth are anchored to the jaw by something called the alveolar bone, commonly referred to as the tooth socket. But no matter what you call it, the alveolar bone is the primary support for your teeth.

Below the Surface

Your teeth are actually much longer than they appear on the surface, with a long root extending below the gums and into your jawbone. This deep anchor provides the strength needed to support the pressures of chewing. The part of the alveolar bone that encases these roots (the actual “socket”) is called the alveolus. At the base of the root is a strong tissue called cementum that fastens each tooth to the alveolar bone foundation

Both the upper jaw (maxilla) and lower jaw (mandible) contain alveolar bone. In addition, a special ligament completes the package, binding teeth securely into place for maximum support.

Alveolar Bone Loss

Certain dental problems and habits, as well as the effects of time, can cause the alveolar bone to resorb, or dissolve. Periodontal disease, also known as gum disease is the major cause of this condition, which makes gum disease treatment an important step in preventing alveolar bone loss.

As always, your dentist is your best resource to find out more about this dental condition. If you think you may be experiencing loss of alveolar bone, Call (310) 858-7373 to make an appointment to discuss your concerns.

Baby Teeth

Few things are as adorable as a baby’s totally toothless smile. But baby teeth development doesn’t take long. Before you know it, you’ll be navigating your way through the world of teething, brushing baby teeth, losing baby teeth and eventually welcoming in a mouth full of permanent ones.

Baby teeth development begins before they baby is born. Primary teeth are almost completely formed at birth but remain buried under the gums. These teeth start showing up when a baby is about six months to a year old.

Unfortunately, baby tooth development and eruption is a painful process. Teething can make an infant’s gums sore, causing your little one to be uncomfortable and irritable. Experts suggest that during baby tooth development, you massage your baby’s gums with a clean finger or give a chilled teething ring, a cool spoon or a cold, wet washcloth to help ease the discomfort.

Parents should begin brushing baby teeth as soon as the first tooth arrives. Why bother? These teeth help baby with proper chewing and speech and hold space in the gums for permanent teeth. By brushing baby teeth early on, you’re creating good oral hygiene practices that will come in handy when your little one’s permanent teeth make their appearance.

Calcium

Calcium is essential for healthy bones and teeth! You’ve heard it before, but how much calcium are you actually getting?

An extremely important mineral for dental and overall health, calcium aids in preventing dental problems and osteoporosis. Actually, 99 percent of the calcium found in our bodies is located in our bones and teeth! But calcium does so much more — it also helps with blood clotting, sending nerve signals, releasing hormones and enzymes, as well as muscle and blood vessel contraction and relaxation.

Much like we change our hairstyles or clothes to resemble the latest fashions, our bones are constantly reinventing themselves. Our bones are continuously undergoing a process called resorption, which is the breakdown of bone tissue. When bone is lost, calcium is deposited to help new bone form. In order to best utilize new bone formation, calcium needs to be taken continuously, and over a long period of time.

As we age, we tend to lose more bone, and it becomes harder for calcium to keep up with our changing bodies. If there’s not a significant amount of calcium, our bones can become brittle and porous in old age. The weaker our skeletal systems, the greater our chances of ending up with bone fractures or jaw deterioration, which leads to tooth loss. And the more the jaw deteriorates, the harder it is for your mouth to support dental restorations, such as dental implants and dentures.

Calcium is equally important to your periodontal health! According to the American Academy of Periodontology, a diet low in calcium can increase your chances of getting gum disease. An infection caused by bacteria that attack your gums, periodontal disease will eventually break down your gum tissue and destroy the surrounding bone. As calcium supports your jawbone, it strengthens it against the bacteria that lead to gum disease and eventual tooth loss. Combined with gum disease treatment, a significant calcium intake can prevent gum disease from progressing.

Cementum

Cementum is a hard layer of tissue that helps the periodontal ligament attach firmly to a tooth. Made of cementoblasts, cementum slowly forms over a lifetime.

Cementum is a hard, calcified layer of tissue that covers the root of the tooth. On its outer side, cementum is attached to the periodontal ligament; on its inner side, the dentin. Along with the periodontal ligament, alveolar bone and gingiva, cementum helps a tooth stay in its place. In fact, if it weren’t for cementum, the periodontal ligament wouldn’t be able to attach firmly to a tooth.

Slowly formed throughout life, cementum is created when the root of the tooth excretes cementoblasts. Though cementoblasts are somewhat of a mystery, it is known that cementum is yellow in color and softer than dentin. Its chemical makeup is similar to that of bone — but unlike bone, cementum is avascular (not supported by blood vessels).

Cuspid

When your dentist asks to see your canines, he probably isn’t talking about man’s best friend. “Canine” is actually another word for cuspid, one of the four pointed teeth on either side of your mouth.

This type of tooth is also sometimes called an “eye tooth” and plays a crucial role in your bite’s formation and function. Problems with your cuspid teeth can affect eating and speaking. While you can find information about dental anatomy on our website, only a dentist can diagnose and treat dental problems. Talk to your dentist if you think you have a problem with your cuspid teeth.

Cuspids are found on both the upper and lower jaws between your incisors (flat front teeth) and premolars (small chewing teeth). If that sounds overly complicated, it may be easier to simply go to the mirror — a cuspid is the third tooth to the left or right of center when you smile. For most patients, they are also the last of the front teeth to erupt (around age 11 or 12) and help keep the rest of your teeth in the correct position as you grow.

You may have noticed that your pointed canines resemble fangs — that’s because, just like our friends in the animal kingdom, we use our sharpest teeth to tear our food while eating. They’re also incredibly strong, with longer roots than any other human teeth, making them particularly well-suited for this task.

And did you know your cuspids also help ensure that your bite aligns properly? Since canines are usually the first teeth to touch when closing your mouth, they help guide your jaw into place to guarantee a proper fit.

Deciduous Teeth

Deciduous teeth are baby teeth. We’re born with two full sets of teeth and this first set is also called primary, milk or lacteal dentition. These teeth begin to erupt anytime after 6 months of age, which is commonly referred to as “teething.” Teeth normally erupt in pairs and the first that normally come in are the lower central incisors. By the time your child is 2, he or she should have a full set of deciduous teeth.

As an infant, our mouths are too small for a full set of permanent teeth, so we require deciduous teeth until our jaw is able to sustain the permanent set. Baby teeth are essential in the alignment, spacing and occlusion of primary teeth. They prepare the adult jaw for their permanent fellows.

As the adult teeth (seccedaneous teeth) form, special cells called odontoclasts absorb the roots of the baby teeth, so that when your adult teeth start to emerge from your gums the deciduous teeth have no roots, making them loose and able to easily fall out.

A gross misconception about baby teeth is that since they will eventually be replaced by primary teeth, there’s no reason to take care of them. But cavities are a very real cause for concern — even for deciduous teeth. Children who suffer from dental cavities in their baby teeth are more prone to cavities in their permanent teeth. And every dentist will agree that oral hygiene habits begin in childhood. So it is essential that you take excellent dental care of your little ones’ baby teeth, as they won’t be able to do so themselves for the first handful of years.

Good oral hygiene begins at teething. Simply rubbing your infant’s gums with a wet washcloth will begin to develop habits that he or she will require for life. Once the first teeth erupt, begin brushing them twice a day. Once more teeth fill in, you can begin flossing, too. And be sure to set up your child’s first dental visit when the first tooth appears or by age 1.

Dentin

Dentin is the technical name for your teeth — well, the substance that makes up your teeth, rather. Dentin is almost bone-like and it makes up most of the structure of your teeth. Dentin is made from cells called odontoblasts and is found under the enamel of the crown and under the cementum in the root.

Dentin is yellow in appearance; it’s the tooth’s enamel that gives teeth their bright white finish. Since enamel is relatively translucent, if not properly cared for by regular brushing, regular flossing and regular dental visits — your teeth can dull and become yellow as enamel starts to wear off. At that point, only the yellowish dentin is left.

“Dentin consists of microscopic channels, called dentinal tubules, which radiate outward through the dentin from the pulp to the exterior cementum or enamel border.” This is all very technical for the biology of dentin, which is a very detailed and complicated process that occurs in the tiniest square footage — our individual teeth!

The highly specialized connective tissue of dentin makes up most of the structure of your teeth. If the inside (pulp chamber) gets infected and is removed by your dentist, dentin will become brittle and can fracture far more easily than normal. This is why, after a root canal, you are generally fitted with a cap or a dental crown.

Facts of Dentin

Dentin is semi-reparable. It has reparative capabilities because the odontoblasts that create dentin remain viable after the teeth erupt. When excessive wear, cavities or other irritants start to degrade the dentin, reparative secondary dentin is laid down.

As helpful as this is, the enamel that covers dentin is NOT reparable, so again, your biyearly trip to the dentist is mandatory, as is daily brushing and flossing.

When you get dental cavities, you get them in dentin. Generally, if you get an infection, you get that in the pulp of the tooth. But enamel can wear away by chewing ice or other irritants, thereby making dentin more susceptible to dental cavities and tooth loss.

Incisor

Incisor teeth are the first eight teeth seen when you smile.
They’re the first teeth you get as a baby — and also the first adult teeth to erupt. Incisors are the teeth located in the front of your mouth. They’re usually the first teeth visible when you smile, not only for their location but for the flat, smooth surface that give them a translucent, white luster.

The word incisor comes from the Latin word “incidere,” or “to cut.” And that is exactly what they are used for. The sharp edges on the bottom of incisor teeth are designed for cutting food. They look flat, but incisors are actually slightly convex, or curved towards the back of the mouth. Another trait of an incisor tooth is it has one single long root, unlike molars, which usually have 2-3 roots per tooth.

Incisor and cuspid teeth fall into the category of anterior teeth, the front six teeth located on both sets of jaws (posterior teeth are located in the back of your mouth and are used for grinding and chewing food). Humans have a total of eight incisors — four on the maxillary (upper) jaw and four on the mandibular (lower) jaw. Both children and adults have incisor teeth, which are labeled according to their position in the mouth:

Central Incisor — Central incisor teeth are in a mesial position, or at the very front and center of your jaw. Maxillary central incisors are the largest and often most prominent of the incisor teeth.

Lateral Incisor — Each lateral incisor tooth is located on either side of a central incisor. In terms of their proximity to central incisors, they are considered distal, or moving away from the center of the mouth.

Take a look in the mirror to pinpoint the location of each incisor. You’ll notice that upper lateral incisors are slightly smaller than the upper central incisors. Mandibular incisors are significantly smaller than maxillary incisor teeth and mandibular central incisors are the smallest teeth teeth in your mouth.

Incisor Tooth Issues

When your bite is in perfect occlusion, or the proper alignment of the jaws and teeth, each maxillary incisor tooth should slightly overlap the mandibular incisor located beneath it. A malocclusion, or bad bite, is a common problem among incisor teeth. A misaligned jaw and crooked teeth can result in an underbite, overbite or crossbite, making it hard for the incisor to do its job. When a malocclusion of the incisor teeth is severe or combined with orthodontic problems in the posterior teeth, dental braces are often needed to correct your bite. If there is only a slight malocclusion in your anterior teeth, veneers can be used to fix the problem.

Anterior teeth are longer, thinner and weaker than posterior teeth, making them more likely to chip or break. Incisors are also subject to cavities and other dental problems that are common in molars. Because of each incisor tooth’s prominent placement in the mouth, tooth stains and other imperfections are often more noticeable than on any other teeth. Good oral hygiene and regular dental visits are necessary to prevent common dental problems from affecting incisor teeth.

Crossbite

The clinical definition for a crossbite is “an abnormal relation of one or more teeth of one arch to the opposing tooth or teeth of the other arch, caused by deviation of tooth position or abnormal jaw position.” But unless you’re a health professional, this definition probably makes you say, “Huh?”

In lay terms, a unilateral posterior crossbite is what occurs when your upper teeth fall inside your lower teeth on one side when you bite down. An anterior crossbite, which is similar to an underbite, is what occurs when your top front teeth fall behind your lower front teeth when you bite down.

Crossbites are caused by a variety of factors. If one or both of your parents has a crossbite, there’s a good chance you could inherit it. Another cause is jaw size — if your upper jaw is smaller than your lower jaw, or your jaws are mismatched in size, you could develop a crossbite.

Children can be prone to developing crossbites if their baby teeth don’t fall out in a timely manner. Here’s why: If the upper permanent teeth start to sprout while baby teeth are still present, they’ll have no room to grow in except behind the baby teeth. When a child bites down, this back row of teeth will fall behind the lower to teeth to create a crossbite.

Large adenoids and tonsils can also spur the development of a crossbite. If a child’s adenoids and tonsils are too large, it may force a child to breathe through their mouth instead of their nose. The difference may seem innocuous, but it can actually affect proper jaw growth: When a child breathes through the nose, the tongue is positioned on the roof of the mouth, which helps the jaws to grow laterally. But if a child is forced to breathe through the mouth, the tongue shifts out of position and away from the roof of the mouth, causing the jaws to grow asymmetrically.

A crossbite is more than just a cosmetic imperfection. So if you suspect that you have a crossbite and wonder how important it is to see a dentist, the answer is “very.” Left untreated, a crossbite can cause conditions such as TMJ or TMD, loose teeth, receding gums, excessive wear of tooth enamel and assymetrical growth of your face and jaw.

Molars

Used for grinding food, molars are the teeth found in the back of your mouth and are usually the final teeth to erupt. Altogether, we have 12 molars, with six molars in each jaw, and three on each side.

Molars are definitely the largest teeth in your mouth! Unlike your front teeth, which are sharp and pointy for biting, your molars have rounded cusps for chewing. Each molar uses two to three roots to anchor itself to your jawbone and keep this strong tooth in place.

There are three different types of molars:

First Molars — The first molars are often called six-year molars, because of the age you are when the permanent, or adult, molars erupt.

Second Molars — Likewise, these are called 12-year molars. You get the picture! Both first and second molars come in the form of primary and secondary teeth. Once your baby teeth fall out, they will be replaced with permanent first and second molars.

Third Molars — The third molars, or wisdom teeth, are the final molars to come in. You’ll probably start to see wisdom teeth erupt between the ages of 17-21. They’re called wisdom teeth because by the time they erupt, we’re supposed to be old enough to have wisdom. Considering most third molars erupt during the late teens, we think they must have been given this title when people had a shorter lifespan!

If you hear your dentist refer to your tooth as a “maxillary first molar” or “mandibular second molar,” he’s referencing the location of each molar in your mouth. As with any of your teeth, the molars located in your upper jaw are known as maxillary molars. In the lower jaw, they’re called mandibular molars.

Permanent Teeth

Most people come equipped with two sets of teeth during their life: baby teeth and permanent teeth. You can protect permanent teeth by continuing the good oral hygiene habits recommended for baby teeth. Brush twice a day, floss once a day and see a dentist regularly. Dental sealants may be recommended as a way to protect vulnerable areas of the teeth by sealing out debris and bacteria.

Since decayed and missing permanent teeth will not regrow, it’s worth learning more about permanent teeth eruption and what to do if your teeth are loose or missing.

The general timing of permanent teeth eruption is somewhat predictable. The first permanent molars come in right behind the last baby teeth molars, usually sometime between 6 and 7 years old. For the next several years, the mouth is in a transition period, with baby teeth falling out and being replaced by permanent ones.

It takes a while for all of the permanent teeth to make their appearance, but by the time they do, there are 32 in total. This includes 12 molars, eight premolars, four cuspids (or canines), and eight incisors. The majority of these teeth will erupt by the early teen years, but the four third molars (or wisdom teeth) will not appear until the late teens or early twenties. Here are the approximate ages of permanent teeth eruption:

Upper Teeth Lower Teeth
Central Incisors 7-8 years 6-7 years
Lateral Incisors 8-9 years 7-8 years
Cuspids (Canines) 11-12 years 9-10 years
First premolar (first bicuspid) 10-11 years 10-12 years
Second premolar (second bicuspid) 10-12 years 11-12 years
First molar 6-7 years 6-7 years
Second molar 12-13 years 11-13 years
Third molar (wisdom tooth) 17-21 years 17-21 years

Primary Teeth

Throughout the human lifespan, our bodies go through several changes. And most of us have embarrassing pictures as evidence of a particularly awkward stage — especially those toothless grins seen during our childhood years.

Also known as baby teeth, primary teeth are our first set of teeth that pave the way for our permanent teeth, and they’re an important part of a child’s development.

Dental health is a major aspect of your infant’s or toddler’s well-being. Parents often have questions when it comes to their child’s primary teeth. Here’s what to expect when you’re expecting — a baby tooth!

Pulp Chamber

It may look like just a bone to you, but the tooth is actually a complicated structure designed to help us chew and speak. In fact, the tooth isn’t a bone at all! The tooth can be broken down into two parts: the crown, which is the part we see, and the root, which is nestled beneath the gum line and anchors our teeth to the jawbone.

Teeth contain several components. The outlying section of the crown is called the tooth enamel, a hard material that protects our teeth from normal wear and tear. Under the enamel is plenty of dentin, which fills a good portion of the crown and acts as a shock absorber.

If you peeled away all the layers of dentin, you’d see the pulp chamber. Pulp chambers are found at the center of the tooth between the crown and the tooth’s root canals. Without it, our teeth wouldn’t be able to tell us that anything is wrong!
The pulp chamber’s roof and walls are made up of outlying dentin. But the pulp chamber isn’t perfectly round — it actually resembles the shape of the crown. The pulp chamber has what’s called pulp horns, which are points where the pulp chamber extends towards the tooth’s cusps. At the bottom of the pulp chamber are orifices which allow fibers to enter the chamber through the roots.

You might think of a chamber as an open space, but the cavity of the pulp chamber is jam-packed with materials. Both the pulp chamber and root canals are filled with a soft tissue, appropriately called the pulp. Dentists refer to the tissue within the pulp chamber as coronal pulp, while radicular pulp pertains to the pulp located within the root canals. As we grow, the pulp helps our teeth develop by supplying nutrients and forming dentin. Once the tooth is fully matured, pulp is no longer needed for the tooth’s survival.

Tooth Enamel

Your skin is designed to protect your body — and your teeth have a protective covering, too! Tooth enamel is a thin, tough coating that covers the crown of your tooth. The hardest tissue in the human body, tooth enamel protects your teeth from everyday wear and tear, including chewing, biting and grinding. Tooth enamel also protects underlying dentin from sensitivity and the plaque bacteria that cause cavities.

Tooth enamel is the part of the tooth you see, but it’s not what determines its color. While tooth enamel may appear white, it is actually translucent — and easily stainable! But preventing tooth discoloration isn’t the only reason you should practice good oral hygiene. Tooth enamel is usually the first place that a dental cavity forms. Once tooth decay penetrates the enamel, it can travel quickly through the softer layers of your tooth until it reaches the tooth’s nerves, resulting in a root canal infection. Protecting your enamel against tooth decay can help it do its job of protecting your teeth!

You need to take care of your tooth enamel — or you risk losing it! Tooth erosion, or enamel erosion, is the wearing away of tooth enamel. Tooth erosion is usually caused by consuming acidic foods and drinks on an ongoing basis and it’s a common problem among soda, wine and coffee drinkers. Enamel erosion can also result from aging, bruxism, dry mouth, acid reflux disease, bulimia or certain medications.

The following symptoms could be a sign that you have tooth erosion:

– Sensitivity to hot or cold
– Tooth discoloration due to the exposure of dentin
– Cracks or chips in teeth
– Teeth that are rounded or transparent in appearance

Dents on the surface of your teeth, known as “cupping”

A tooth filling that appears “raised”