Let's Talk about Teeth: Houdini/VFX Applications
So I thought this was one subject matter lacking content around the internet. So here is my take on 3D teeth and building them in Houdini.
Types of Teeth
Let's start out with the different types of teeth in your mouth. Most people have 32 teeth in their mouth when they reach adulthood. But 36 if you count your wisdom teeth. These 32 teeth can be categorized into 4 different types. These types can also been seen in other animal species.
These are teeth that help your cut up food. They are located at the front of your mouth. They are also known as your two front teeth, but you have about eight of them in your mouth.
These are elongated and pointy teeth. In a human mouth, there are about four of them on either side. Two of these teeth are known as the maxillary canines, and the other two are known as the mandibular canines. They are primarily for grabbing food so the rest of your teeth can tear it apart.
These teeth are also known as bicuspids. These teeth help you crush and tear food. They are located between the canine and molar teeth, and there are about eight of them in your face.
These teeth chew and grind food. They are located in the back of your mouth. They are classified more as vestigial organs than teeth in mammals. A vestigial organ is an organ that though evolution has lost its original purpose, and is not really necessary for bodily functions. Adult humans have about 12 molars, including the wisdom teeth.
Every tooth also has the same basic anatomy.
- The root is the part of the tooth that holds it in place in your jaw bone. It makes up two thirds of the tooth.
This root is made up of several different parts.
It’s made up of several parts:
The Root Canal:
.- The root canal contains the dentin or pulp of the tooth. This pulp contains the blood vessels and nerves keeping the tooth alive.
- This is basically the covering of the tooth. It protects it from damage, and overall wear from chewing. It is connected to something called the periodontal ligament.
The Periodontal Ligament:
- The periodontal ligament is made of connective tissue and collagen fiber. It contains nerves and blood vessels. It connects the teeth to the tooth sockets
Nerves and Blood Vessels:
- Blood vessels supply the tooth with blood, and keep it alive. Nerves control the sensitivity of your teeth. They also control the amount of force when you chew.
The Jaw Bone:
- The jaw bone holds the teeth in place. It also contains the tooth sockets that surround the roots of the bone.
Teeth also have a neck. It is also called the dental cervix. It is located between the crown and root. It contains a lot of elements that keep the tooth alive.
It has three main parts:
Gums are the pink flesh surrounding your teeth. They also help hold your teeth in place.
- It’s made of tiny blood vessels and nerve tissue.
The Pulp Cavity:
This is the space inside the crown that contains the pulp. It is also inside of The Root Canal.
- This is the visible area of the tooth in your mouth. This includes:
The Anatomical Crown:
- This is the top portion of a tooth. It’s usually the only part of a tooth that you can see.
- This is the outermost layer of a tooth. As well as the hardest tissue in your body, it helps to protect teeth from bacteria. Enamel is the strongest and most mineralized substance in the body.
- Dentin protects teeth from heat and cold.
Animals fall into three different groups based around their eating habits. Carnivores only eat meat, herbivores only eat plants, and Omnivores eat both. Because of this their teeth can vary per species. Carnivore teeth are designed to rip and shred meat, and herbivore teeth are built to squash and grind substances.
Animals like beavers constantly grow new enamel due to their teeth being a tool in their survival. Some animals such as the narwhal have teeth growing from their mouths that break through their skin, and grow through body parts. This is known as their tusk or horn. This horn is classified as a tooth. Sometimes narwhals grow an extra tooth, and become a two tusked narwhal.
Some animals also have more than 32 teeth in their jaw. Snails have more than 25,000 teeth, and they are located on their tongue. They are also the strongest known material on Earth. Hippopotamus usually have a set of 40 teeth, and Armadillos have 104.
Sharks are also pretty special in the teeth department. Unlike most animals that have and lose only two sets of teeth over their lifetime. Sharks constantly lose teeth over their lifetime. So much so that they can lose up to 35,000 teeth by the time they die.
Human teeth are a bit different than regular animal teeth. But they also share similar traits with other mammals. Most mammals are considered diphyodont. This means over the course of their lifetimes they have two sets of teeth. Humans are born and develop their baby teeth, which are usually a set of 20 teeth. Then in their teen years develop their adult teeth. As we've mentioned above, these teeth can fit into a few different categories. These categories are: incisors, canines, premolars, and molars.
Male and female teeth are also a bit different. Human males have larger jaws and also less enamel in their teeth than females. Humans are one of the few species that can't regenerate enamel, so once we break our adult teeth, we need medical attention. Because humans are omnivores, this means our teeth have traits seen in both carnivores and herbivores.
Time to talk about dental simulations! This topic can be very fun, but you'll quickly notice that most of the dental simulators out there are centered around veterinarian and human dental care. These simulators are still pretty helpful, as they can give you a baseline for how human and animal jaws are positioned. As well as illnesses your mouth can develop. So let's take a look at some teeth.
Starting with Humans.....There are countless dental sites you can go to on the web. One of the most accurate and expensive simulator sites you can find is medicalexpo.com. They have a variety of simulations showing you how to operate on human teeth, and use the medical equipment needed for the procedures. They also have other ones for other treatments in human and animal bodies. Even though they are a site where pretty much any medical company can sell their products on, I think they showcase how 3D models and scans are being used to teach students. As well as the other rendering and environments they use. They also have a very fascinating medical blog.
There are also a few Canadian companies that have developed simulators for teeth surgery on dogs. These vet simulators are not done on a computer, but rather are 3D scans of dog's mouths that have been 3D printed for medical training. They are physically accurate, have simulated teeth, gum, and bone structures, and can simulate teeth nerve damage. All from a 3D scan.
Teeth simulations are often used for Invisalign and other braces procedures. Often these sims will show how these braces will change the location of a person's teeth, but are also only for show.
Virtual reality also plays a bit factor in the way dental simulators are being used. Some sites, like this one HERE, are perfect examples. It's one thing to play a simulator with your mouse, keyboard, or Xbox. It's another to walk around in a full medical environment. Which is exactly what students and teachers need to train each other in. In a VR environment you can fully interact with any situation and outcome. Which is way better than practicing on a real patient and risking mistakes.
Examples in Houdini
So if you do a quick artstation or google search, you'll notice that there aren't currently a lot of teeth simulations out there. But it is quite possible to model teeth in Houdini. You can get a basic structure of a carnivorous tooth by poly extruding a box, and tapering it into a tip. Or just using a tube instead. Creating the smaller details of the teeth might be a lot harder, as they may be based around whichever character/creature you are basing them from.
Personally, I think it's quite possible to get a pre-made model of a jaw, and then simulate grinding and crushing effects with them in the software as well. This in tandem with the vellum system would create some awesome meat and flesh shredding. You can buy your own set of 3D teeth from badship.com, for about $30. But you could also take a shot in the dark and make your own dental simulator. Houdini has been used in medical visualization a lot, and there are huge possibilities for it in the dental industry.
On a side note you should check out this GitHub, which shows you how to bring in medical data into the software: HERE.
It's probably the best Houdini medical toolset out there.
Teeth also play a huge role in character effects and design. If you have seen the film Love and Monsters on Netflix, you see some great examples of this. During certain parts of the film, the monsters have their mouths wide open, and they suddenly become terrifying. This can be because of their insane amounts of teeth, or lack thereof. But their teeth also match their design, and species type. The frog in the film only has a tongue, and the crab has teeth that would match it's internal gastric mill. So understanding where teeth should be on a creature can make it extremely real in your final models. Honestly, Joel is pretty lucky that he survived that snail. Because 24,000 of the world's strongest teeth would have hurt a lot.
Teeth can also define the age of a character, express how they enjoy food, and the overall expressions and habits that they may have.
A good way to see if your teeth match your character is to go over this question checklist in the back of your mind:
- Do the teeth align with the overall jawbones of my character's face?
- What does my creature consume? Do they eat meat, veggies, people, everything....?
- If my creature is based off a certain animal, will its teeth grow back, fallout, or change based on it's size?
- Should the teeth of my character interact with the lips or upper mouth palate at all?
- If I need to break my character's teeth, do I need to add any underlying details so when it shatters I can see the structure of it?
- Where are the teeth located on my creature? (head, tongue, jaw bone, stomach, etc.)
- How will the jaw of my character move?
- Where are my characters teeth in regards to their facial expression?
- What does the wear and tear of my character's teeth look like?
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