Today’s post is about some teeth “basics”. What their functions are, what they are made of, and their inner workings. For most, this may be just a review, but important information because the next few articles will be about tooth sensitivity: its causes, and how to help stop or at least reduce it. For that, you need this basic information first.
Tooth Basics
So, for those new to the whole “teeth” thing: They have some very important jobs to do and often they get no respect. They literally start the process of digestion. They help you speak clearly. They develop and maintain the shape of the face. For animals, teeth are used for defense. And for humans, they are part of a beautiful smile and a source of self-confidence.
Teeth really are incredible. They work hard for you every day chewing, grinding, and mashing food. Teeth on the whole should silently do their “jobs”. Their jobs depend on where they are located in the mouth. Teeth should never hurt or be sensitive. If they do, that’s their cry for help.
Unlike sharks, who can get up to 50,000 teeth in their lifetime, humans only get two sets of teeth.
The “baby teeth” and the “adult teeth”. Adults should end up with 32 teeth but most only have room for 28 (that’s a post for another day). We call that the permanent dentition. (At least it should be permanent and that’s why I write this blog, to help you make things healthier and more permanent.)
Baby Teeth
Your baby will have 20 teeth by the time they are three years old, with their first tooth coming in around six months. (Although every baby has their timetable for “erupting”. And, it literally is an eruption into the mouth, and yes, it is painful.) In dental lingo we call this the “primary dentition” and we call baby teeth- “deciduous” teeth. You may know it as baby teeth or milk teeth.
Baby teeth are just as important as permanent teeth. They perform all the same functions as adult teeth- start the digestive process, grind food, help with proper pronunciation and speech, and contribute to self-esteem. Who doesn’t love a toothy/gummy baby smile? You smile back and that releases hormones and stimulates the baby’s brain development. Smiles tell your baby all is loving and right in their world. And, getting those cheeky, happy smiles makes you feel good too.
Care for baby’s teeth just as you care for your own. Brush them well. Feed them good, nutritious foods. Skip the baby foods which are too mushy. Teach baby to chew. Chewing is critical to proper jaw and facial growth, clean healthy teeth, and proper airway development. Harder foods are healthier foods (for the most part.) Breastfeeding is best feeding and does not cause cavities. It is the mushy, sticky carbohydrate foods that babies and toddlers eat that are the big part of the cause of tooth decay.
Healthy baby teeth hold the space for the permanent teeth to erupt into the jaw. The primary teeth need to have enough spaces between them so they look like a picket fence. Ideally there is enough room in-between teeth so you could (theoretically) put a nickel between each front tooth.
Babies get tooth decay and feel pain in the same way adult teeth do. Please do not dismiss it as unimportant with the idea they will fall out so they don’t matter. (I have heard parents say these things.) Baby teeth start falling out around age five and continue to do so until about age 12/13/14. They are there for a long time so they really need loving care.
The Dentition
We call the development and arrangement of teeth in the mouth the “dentition”. “Dens” is the root meaning of tooth and the “ist” is the person who “does or makes”. Hence, the dentist is one who fixes and repairs teeth.
Incisors
We call the upper jaw the maxillary arch and the lower jaw the mandbular arch. Both arches have the same types of teeth. We start with the four front teeth called the incisors: two central incisors – your front teeth and next to them are the lateral incisors. Both the primary and permanent dentitions have these eight incisors. Besides looking pretty, their main job is to bite into and tear food. They also help us pronounce and enunciate words clearly, and support the lips which supports our airways.
The incisors are NOT made for chewing and breaking down food. If they are used for chewing food they will start falling apart. (No surprise… but they also should not be used as tools either- tearing bags or opening bottles are a big no-no.)
Cuspids
Each arch has two cuspids- you know them as canine or eye teeth. These teeth are the anchors of the arches and make the jaws nice and rounded. They are the teeth with the longest roots. Without them, faces look flat. They guide the teeth into proper alignment when the mouth closes and the jaws come together in a chewing motion. Their sharp point assists in tearing food. In the animal world, they are used for self-defense.
Bicuspids
In the permanent dentition, right behind the cuspids and in front of the molars are two premolars on each side of the mouth and on both arches. They are also called the bicuspids. (We in dentistry are fancy and call them the “first bi” and the “second bi”. Now you can amaze and dazzle your dental hygienist with all the proper lingo.) You will have eight of them. The bi’s have two cusps or peaks, thus the name. These are transition teeth- between the front of the mouth to the back molar teeth. Their job is to grind and mash food.
Primary dentitions do not have bicuspids. They go from the canine directly to the baby first molars. The baby molars hold the space for the bicuspids to erupt into the jaw at about the age 12 to 13.
Molars
And the workhorse of the mouth – the molars. Baby dentitions have eight molars and the permanent dentition should have 12 molars. They have just as fancy names- “first molar”, “second molar” and “third molars”. You know third molars as “Wisdom Teeth”. Sadly, most people do not have room in their jaws for their third’s so they are removed by oral surgeons regularly.
Molars have four or more cusps and their main job is chewing, crushing and grinding our food. Ninety percent of chewing takes place between the molars.
There are four baby molars on each of the arches. Baby molars have the same job as permanent molars. They are in the mouth until the child is 12 to 13 years old so caring for these teeth is critical. Baby teeth are place holders for permanent and do the same jobs for children as permanent teeth SO, they need the same care. I hope you sense a theme here. I cringe and am deeply saddened when I hear parents say “they are ONLY baby teeth”.
To make discussing teeth easier, in our dental lingo we identify teeth by number. In the permenant dentition, we number teeth from one to 32, starting with the third molar on the upper right as tooth #1 all the way over to the upper left third molar as #16, then the lower arch third molar is #17 all the way over to the lower right third molar is named #32. Baby teeth are identified by letters. A, J, K, T are the last teeth on each arch. (They are also a family member’s initials so that helps me remember baby teeth letter names.)
Tooth Anatomy Lesson
Above the Gumline
The crown portion of the tooth is covered above the gum line with enamel. Enamel is the hardest substance in the body. It is made up of hydroxyapatite, calcium and phosphorous, magnesium, sodium and carbonate.
Below the Gumline
Fun shark fact: Shark teeth have no roots so they break off easily but, the next tooth is waiting in line to take its place. They can have up to 15 rows of teeth and are continuously growing new ones.
Human teeth, on the other hand, have long roots below the gum line. The roots of the teeth are covered by the cementum and are housed in the bone. The cementum and the periodontal ligament fibers anchor the tooth to the jawbone. Cementum is made up of 45 to 50 % hydroxyapatite crystals, 50 to 55% organic matter, and then water. The unique thing about cementum is it is living tissue and constantly repairs itself throughout life. The main function of the cementum is to anchor the tooth into the bone, and protect and cover the roots. The cementum is yellowish in color. It is not as hard or as thick as enamel. It meets up with the enamel at the gumline at what is called the cemento-enamel junction or in dental parlance: the”CEJ”.
Underneath it All
Beneath both the cementum and the enamel is the layer called the dentin. Dentin is made of hydroxyapatite crystals, organic material, and water. It is also yellowish in color although that can vary more. It is also softer than cementum or enamel.
The dentin is composed of dentinal tubules. Miles of tubules- somewhere I learned it was on average about three miles of dentinal tubules – I can’t verify but am still looking so when I find my soucre I’ll link it here. But, suffice it to say there are many, many, many tubules.
These tooth tubules are filled with fluid. This dentinal fluid flow is called the dentinal transport system and brings nourishment from the pulp chamber to the rest of the tooth. Research shows this fluid moves through the entire tooth and out into the mouth. It brings the tooth vitamins, minerals, enzymes, and other nutrients from the inner workings of the body and through the pulp chamber to the rest of the tooth. The key to tooth health is this fluid. The problems start when this fluid flow is stopped or reversed – think “backwash” from the mouth into the tooth bringing with it acids, and bacteria, and other microbes from the mouth, down the tubules, and into the inner tooth structure. This is part of the root cause of tooth decay as well as tooth sensitivity which we will dive into in the next post.
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Teeth Basics
Teeth put up with a lot: clenching, grinding, acidic environment, and so much more. Yet for the most part silently work hard for us every day. In our next posts, we will dive into how a tooth gets damaged and its responses to that. (I hate it when a tooth talks back!) Then we’ll address how to help heal the tooth and when it’s not possible. I want you to be able to enjoy a glass of ice water on those hot summer days.
Hope you learned a few new basic teeth things, enjoyed your lessons in dental lingo and the fun facts on shark teeth!
Warmly,
Barbara Tritz
Queen of Dental Hygiene and Princess of Shark Teeth
