All-On-4 Dental Implants
Baltimore, MD

The most lifelike way to replace a full arch of failing or missing teeth with dental implants.

all-on-4 upper bridge

What Are All-On-4 Dental Implants?

all-on-4 upper bridge
The All-On-4, “Teeth in a Day” procedure consists of removing any remaining teeth, placing implants, and then securing a beautiful, fixed, functional smile over the course of a single day!

This procedure will not only give patients the beautiful smile of their dreams, but also give them a fresh outlook on life. We see countless patients suffering with extensive decay, old or failing dental work, and broken teeth. For these patients, All-On-4, “Teeth in a Day” is the perfect solution to obtain a beaming smile and fix the dental problems that have plagued them for years.

  • Best looks/aesthetics | Looks and feels like natural teeth.
  • Best chewing capability compared to other full mouth tooth replacement options.
  • Does NOT cover the roof of your mouth!
  • No long healing times before your dental implants are ready to use normally.
  • Non-removable | Doesn’t come in and out like a denture.
  • Requires the least amount of bone | Great for people with less bone mass.
  • Taste your food better!

How it Works

The All-On-4 procedure involves removing your remaining teeth, placing 4-6 implants per arch, and securing a low-profile bridge to the implants. The implants are often placed at specialized angles to avoid the patient’s sinuses. This also avoids the need for expensive bone grafts that come with long healing times.

The traditional All-On-4 procedure involves 4 implants and acrylic denture teeth over a titanium frame. Our doctor has modified this procedure to provide an even better result for her patients based on her experience successfully placing countless dental implants. At Be More Dental Implant Studio, we carefully analyze each and every case and base our treatment on your individual anatomy. Your doctor will place between 4 and 6 implants per arch and temporary fixed bridges will be secured while your implants integrate with your jawbones and your mouth heals.

After your healing is complete, the doctor and lab technician will design your final All-On-4 teeth with zirconia, which is a premium material that’s much stronger than the traditional acrylic (plastic) denture teeth offered at most other dental offices. Zirconia gives a more natural, life-like result which is also more hygienic and resistant to staining. This means your teeth will last longer and look better than the acrylic/titanium hybrid bridges you’ll find with many other All-On-4 specialists.

Am I a Candidate?

Most patients will be a candidate for the All-On-4 procedure, even those who have been told they don’t have enough bone for dental implants. Your doctor will use a combination of straight and angled implants to avoid the sinuses and engage the strongest part of your jawbone. This technique usually removes the need for expensive and lengthy sinus augmentation bone grafts.

Your doctor will perform a thorough evaluation during your consultation to see if All-On-4, “Teeth in a Day” is a good option for you.

Why Zirconia is Better Than Traditional Denture Material

Zirconia is the “gold standard” material for the All-On-4 procedure. Zirconia is a type of ceramic that is extremely durable and resistant to wear and corrosion, making it an excellent choice for All-On-4 dental restorations.

One of the main benefits of using zirconia for All-On-4 dental implants is its strength and stability. Zirconia bridges can withstand high chewing forces without cracking or chipping, ensuring that your new teeth perform impeccably for decades. Zirconia is also biocompatible, which means it’s unlikely to cause an allergic or inflammatory reaction. This makes it an ideal option for patients with sensitive or allergy-prone skin.

Another advantage of zirconia dental implants is its stunning, natural-looking appearance. Unlike metal or acrylic, zirconia has a translucent quality that closely mimics the look of natural teeth, giving your new teeth a realistic and aesthetically pleasing appearance.

Finally, zirconia is easy to clean, maintain, and can be easily polished to keep its shine and prevent discoloration over time. This helps ensure the longevity and durability of your new All-On-4 teeth.

Overall, zirconia is an excellent choice for All-On-4 dental implants, offering a number of benefits that make it an attractive option for patients seeking a beautiful, long-lasting, natural-looking, and easy-to-maintain smile.

Full-Mouth Implants vs. Traditional Dentures

Life-Changing Results

Same-day smiles from actual patients

Before and after dental implants in Baltimore at Be More Dental Implant Studio
Before and after dental implants in Baltimore at Be More Dental Implant Studio
Before and after dental implants in Baltimore at Be More Dental Implant Studio
Before and after dental implants in Baltimore at Be More Dental Implant Studio
Before and after dental implants in Baltimore at Be More Dental Implant Studio
Before and after dental implants in Baltimore at Be More Dental Implant Studio

All-On-4 Dental Implants Cost

Pricing includes all extractions, as many implants as needed, bone grafting, fixed temporary teeth, and fixed final teeth.

All-On-4

Single Arch

$15,990

Double Arch

$31,800

Price includes extractions, implants, bone grafting, and fixed 3D printed hybrid ceramic resin teeth

Your Smile™

Per Arch

+$3,999

Full Zirconia final bridge – most durable and ideal aesthetics

Available Financing Options

Dental Implants are an important investment in yourself. Having the option to break this investment down into monthly payments can help make these life-changing services more accessible and easier to fit into your budget. We work with a variety of financing providers that offer payment plans to cover either all or part of your dental implant procedure. This is a great option for all patients, especially those who are on a fixed income. With these flexible financing options, you can enjoy the benefits of a healthy, beautiful smile without breaking the bank.

Contact us to learn more about our financing options and schedule your FREE Consultation with Dr. Hurley today!

Frequently Asked Questions

All-On-4 Dental Implants Baltimore, MD

Will I be able to eat with my teeth from day one?

After undergoing an All-on-4 dental implant surgery, it’s important to allow sufficient time for your mouth to heal and for the implants to integrate with the jawbone. While you may be able to resume eating relatively soon after the procedure, it’s unlikely that you’ll be able to eat with your teeth normally from day one.

Immediately after the surgery, you’ll likely experience some swelling, discomfort, and tenderness in the surgical area. It’s essential to follow your dentist’s post-operative instructions, which may include a soft or liquid diet for the initial days or weeks. This diet will help prevent damage to the surgical site and promote healing.

Over time, as the implants stabilize and your mouth heals, you’ll gradually transition to a more varied diet. Your dentist will guide you on when it’s appropriate to introduce harder foods and resume normal eating habits.

It’s important to note that the timeline for recovery and the ability to eat with your teeth can vary from person to person. Factors such as your overall health, bone density, and how well you follow post-operative instructions can influence the speed of your recovery.

At Be More Dental Implant Studio, our All-On-4 cost starts at $15,900 for a single arch. Both arches (full mouth) start at $31,800. To upgrade to premium zirconia final bridges it will cost an additional $3,999 per arch.

We are completely transparent with our pricing with no hidden fees or add-ons. These prices include:

  • Extractions
  • Implants
  • Bone grafting (except sinus lifts)
  • Oral sedatives
  • Fixed temporary teeth and fixed final zirconia teeth

The All-on-4 dental implant procedure was developed by Portuguese dentist Dr. Paulo Malo in the late 1990s. Dr. Malo developed this innovative treatment concept as a solution for patients with significant tooth loss or those who were facing the prospect of complete edentulism (no natural teeth remaining). The procedure aimed to provide a fixed and efficient solution for full-arch rehabilitation using dental implants.

The All-on-4 technique involves the strategic placement of four dental implants in the jawbone to support a full arch of prosthetic teeth. The implants are strategically positioned to maximize bone support and minimize the need for additional bone grafting procedures, making it a viable treatment option for patients with reduced jawbone density.

Since its introduction, the All-on-4 procedure has gained widespread recognition and acceptance in the field of implant dentistry. It has provided many patients with a reliable and efficient option for restoring their smile and improving their quality of life. Over time, variations and refinements of the technique have been developed, but the core principles of the All-on-4 concept remain the same.

Caring for your All-on-4 teeth is crucial to maintaining their longevity and keeping your oral health in excellent condition. Here are some tips for caring for your All-on-4 teeth:

  1. Practice good oral hygiene | Brush your teeth at least twice a day using a soft-bristle toothbrush and a non-abrasive toothpaste. Be thorough in cleaning all surfaces of your teeth, including the gums and the areas around the implants. Additionally, use an antimicrobial mouthwash recommended by your dentist to reduce bacteria and plaque buildup.
  2. Floss daily | Despite having full-arch prosthetic teeth, it’s still important to clean the spaces between the gums and the base of the prosthetic teeth. Use a floss threader or an interdental brush to clean these areas carefully. Your dentist can guide you on the best flossing technique for your All-on-4 teeth.
  3. Attend regular dental check-ups | Visit your dentist for regular check-ups and professional cleanings. They will assess the health of your All-on-4 teeth, monitor the condition of the implants, and address any potential issues at an early stage.
  4. Avoid hard or sticky foods | While All-on-4 teeth are designed to withstand normal chewing forces, it’s still advisable to avoid excessively hard or sticky foods that can put excessive stress on the prosthetic teeth or dislodge them. Opt for a balanced diet that includes a variety of nutritious foods to support your overall health.
  5. Protect against teeth grinding (bruxism) | If you have a habit of grinding or clenching your teeth, inform your dentist. They may recommend wearing a nightguard or suggest other measures to protect your All-on-4 teeth from excessive force and prevent damage.
  6. Be mindful of lifestyle habits | Avoid tobacco use and excessive alcohol consumption, as these can have negative effects on your oral health and increase the risk of implant failure.
  7. Maintain overall health | Take care of your general health, as it can influence the success of your All-on-4 teeth. Follow a healthy lifestyle, manage any chronic conditions, and inform your dentist of any changes in your medical history or medications.

New dental implant arches, including those used in All-on-4 procedures, may feel different from natural teeth initially. Here are some aspects of the experience that you may encounter:

  1. Stability | Full-arch dental implants are designed to be stable and secure. Once the implants have fully integrated with the jawbone, the arch should feel firm and stable, similar to natural teeth. This stability allows you to bite and chew comfortably without worrying about the arch shifting or coming loose.
  2. Sensation | While dental implants themselves do not have nerves, the surrounding gum tissue can still provide a sense of pressure and touch. You may experience a different sensation compared to natural teeth, but over time, you should adjust to the feeling of the implant bridge in your mouth.
  3. Speech | It’s common to experience slight changes in speech initially after getting full-arch dental implants. This can be due to the presence of the prosthetic teeth and adjustments your tongue and oral muscles need to make. However, with practice and time, your speech should return to normal as you adapt to your new teeth.
  4. Comfort | Full-arch dental implants are custom-made to fit your mouth and provide optimal comfort. The materials used, such as ceramic or zirconia, are designed to mimic the appearance and feel of natural teeth. Initially, there may be some mild discomfort or soreness as your mouth adjusts, but this should subside as the tissues heal.

It’s important to note that everyone’s experience may vary, and it may take a short period of adjustment to fully adapt to the feel of your new dental implants. If you have any concerns or persistent discomfort, it’s recommended to consult with your dentist. They can assess the fit and make any necessary adjustments to ensure your comfort and satisfaction.

During the All-on-4 dental implant procedure, you will be under anesthesia, which helps ensure that you don’t experience pain or discomfort during the surgery itself. The use of local anesthesia and/or sedation will depend on your specific needs and the recommendation of our dentist.

If you have concerns about pain management or if you experience severe or prolonged pain after your All-on-4 procedure, it’s crucial to contact our office promptly. Our dentist can evaluate your condition and make any necessary adjustments or provide additional guidance to ensure your comfort and well-being throughout the healing process.

After an All-On-4 procedure, it is common to experience some degree of discomfort or pain. The level of pain can vary depending on individual factors such as pain tolerance, the complexity of the procedure, and the body’s healing response. Typically, the first 48 hours after the procedure is when you will experience the most discomfort. However, the pain is typically manageable and should subside over time as the healing progresses.

Bleeding after the All-On-4 procedure is normal and expected during the immediate post-operative period. The duration and amount of bleeding can vary from person to person, but typically it should subside within the first 24 to 48 hours after the surgery.

If you notice that bleeding persists beyond the expected timeframe or if you experience severe or uncontrollable bleeding, it’s important to contact our office immediately. We can evaluate your situation and provide appropriate guidance or interventions to address the issue.

Yes! We offer a couple options for sedation depending on what is the right fit for you:

Oral Conscious Sedation involves a prescription for sedative pills that are prescribed to you by our doctor. Sedative medication is typically given the night before to help you sleep, as well as the morning of your procedure to ensure your comfort throughout the procedure.

IV Sedation involves the intravenous administration of sedatives in order to put you in a diminished state of consciousness throughout the entire procedure. This also has other benefits for reducing post-operative swelling and pain.

Drooling occurs when a foreign body stimulates the saliva response. This is designed to aid in the breakdown of food when you are chewing. A new denture will mimic that response but don’t worry, your body will adapt and you will return to a normal saliva response in a few days.

The recovery time for an All-on-4 procedure can vary from person to person, and it depends on several factors such as your overall health, the complexity of your case, and how well you follow post-operative care instructions.

Typically, the initial healing takes a few weeks. Complete recovery and adjustment to the new teeth can extend over several months. Each person’s recovery time can vary, so it’s best to consult with our dentist, who can provide more specific information based on your individual case and guide you through the recovery process.

There are many things that we do at Be More Dental Implant Studio that set us apart. From our delicate and personalized care, to our ability to reduce cost through the use of cutting-edge technology, we strive to go above and beyond to deliver the highest level of care at the best price in the area.

Many dental implant practices will advertise a low price as “bait”, and add additional costs for their premium options. Not us – all of our prices include top-of-the-line final zirconia bridges and there are no hidden costs or fees.

At Be More Dental Implant Studio, you will get your All-on-4 procedure at the lowest cost, in the fewest number of visits, with the best final result.

While this may be a good option for some patients, in the rare case of complications, it may be difficult to continue working with the same doctor who placed your dental implants if you traveled thousands of miles or out of the country. Most local offices will not be willing to fix these “out of town” cases. One advantage of having a temporary set of fixed teeth on the day of your surgery is that you get to test them out and see what you like and don’t like. For your final zirconia bridges, we can do try-ins to ensure that your teeth look exactly how you want them to look. While it’s great to get your final teeth immediately, it does come with some serious downsides that should not be overlooked.

We recommend having them cleaned at least once a year.

No, All-on-4 bridges are not always attached to the implants on the same day as the procedure. The timing of attaching the bridge depends on the individual case and the recommendation of our dentist. Here are two common approaches:

  1. Immediate loading | In some cases, immediate loading or immediate function may be possible. This means that the All-on-4 bridge is attached to the dental implants on the same day as the procedure. This approach requires careful assessment of factors such as implant stability, bone quality, and the patient’s overall health. Immediate loading can provide patients with immediate functional teeth, avoiding the need for a temporary denture or extended healing time without teeth. However, not all patients are suitable candidates for immediate loading, and it depends on individual circumstances.
  2. Delayed loading | In other cases, a delayed loading approach may be recommended. This means that the dental implants are allowed to heal and integrate with the jawbone for a period of time before attaching the All-on-4 bridge. This healing period, known as the osseointegration phase, typically lasts several months. During this time, temporary dentures or provisional prosthetic teeth may be worn to maintain esthetics and function. Once osseointegration is achieved, the final bridge or prosthetic teeth are fabricated and attached to the implants.

The decision regarding immediate loading or delayed loading is made based on factors such as implant stability, bone quality, surgical complexity, and the patient’s specific needs. Our dentist will evaluate your case and recommend the most suitable approach for you.

After an All-on-4 procedure, it is important to follow our dentist’s specific instructions regarding oral hygiene practices, including the use of a water flosser or Waterpik. Generally, you should wait until the healing process is sufficiently advanced (typically 1-2 weeks) before incorporating a water flosser into your oral hygiene routine.

If the quality of the bone can achieve enough primary stability to pass a specific threshold, then the implants can be connected to a denture during the healing phase. The denture splints the implants together, allowing it to not move, thus they will predictably integrate into the bone.

Don’t let one dentist’s opinion keep you from pursuing a life-changing solution with All-On-4 dental implants. There are several techniques in implant placement that can be used to have a successful outcome.

Yes! This is the ideal situation because you will have the most bone volume the day the teeth are removed.

Yes, food can get stuck underneath the bridge(s). That is why we recommend daily use of a Waterpik and Proxabrushes for cleaning.

High quality Zirconia. To learn more about Zirconia click here.

Generally, 4-7 days is sufficient. With that said, there is always the chance of bruising and swelling, and you’ll need to get used to eating and speaking with your new teeth. The longer you can take off the better.

We invested in the latest dental technology to have a full in-house dental lab that allows us to take advantage of cost efficiencies that we pass on directly to our patients. This means our patients get the best possible dental product at the lowest price possible.

Yes! We work with a number of financing companies. Patients who would like to break their treatment costs into affordable monthly payments can benefit from working with a financing company. It’s easy and quick to apply for, and you’ll receive a decision right away so you can proceed with your treatment promptly. Click here to view our financing options.

Yes! At Be More Dental Implant Studio, we’re committed to standing by our work – which is why we offer an industry-leading 5-year warranty on your All-on-4 treatment provided that you come in for routine maintenance visits.

For more information on our dental implant warranties visit our Maintenance and Warranties page.

Absolutely not! There are many reasons why younger people might need a new set of teeth supported by implants. From an injury, to poor dental hygiene, even prior drug use – we’ve seen it all and will make you feel welcome, comfortable, and at ease from the moment you step through our doors.

The All-On-4 procedure is typically recommended for individuals who have multiple missing teeth, severely damaged teeth, or significant tooth loss. It is designed to provide a fixed and functional set of teeth supported by dental implants.

There’s no better time than the present to get the life-changing dental treatment you need to live your best and most confident life! Give us a call and we will make sure to get you in for a Free Consultation right away!

Preparing for your recovery after the All-On-4 procedure can help ensure a smoother healing process. Here are some items you may want to have ready:

  1. Prescription medications | If our dentist has prescribed any medications, such as antibiotics or anti-inflammatory drugs, be sure to have them filled and ready to use as instructed.
  2. Ice packs | Cold packs or ice packs can help reduce swelling and alleviate discomfort in the immediate post-operative period. Have a few ice packs ready in your freezer to use as needed.
  3. Soft and nutritious foods | Plan and stock up on soft, nutritious foods that are easy to eat during the initial healing period. Examples include soups, smoothies, mashed potatoes, yogurt, oatmeal, and soft fruits. Avoid hot or spicy foods that could irritate the surgical sites.
  4. Oral hygiene supplies | Follow our dentist’s instructions on oral hygiene practices after your procedure. Make sure you have a soft-bristled toothbrush, gentle mouthwash (if recommended), and any prescribed oral rinses or gels. Our dentist may also advise on a specific technique or schedule for oral care.
  5. Saltwater rinse ingredients | Prepare the ingredients for a saltwater rinse, which can aid in keeping the surgical sites clean and promote healing. Mix 1/2 teaspoon of salt with 8 ounces of warm water. Have a supply of this solution ready for use, as recommended by our dentist.
  6. Gauze pads or sterile cotton balls | Our dentist will provide sterile gauze pads to control bleeding and protect the surgical sites. Ensure you have an adequate supply on hand.
  7. Over-the-counter pain relievers | In consultation with our dentist, you may consider having over-the-counter pain relievers like ibuprofen or acetaminophen available to manage any discomfort during the healing process.
  8. Entertainment and comfort items | During the initial recovery period, you may be resting at home. Have some books, magazines, movies, or other forms of entertainment available to keep you occupied. Comfort items like extra pillows and blankets can also help enhance your comfort.

After an All-On-4 surgery, you may need some time to adjust to and learn how to use your new teeth properly. While the process of adapting to the new teeth varies from person to person, here are some general considerations:

  1. Immediate adjustment | It’s common to feel a sense of novelty and difference when you first receive your new teeth. The size, shape, and position of the prosthetic teeth may feel different in your mouth compared to your natural teeth. Initially, you may need to consciously make adjustments to your bite and chewing patterns to accommodate the changes.
  2. Speech adaptation | Your speech may be affected temporarily after the All-on-4 surgery and the placement of the prosthetic teeth. Certain sounds or pronunciations may require practice and adjustments as your tongue and oral muscles adapt to the new teeth. Regular speaking and practicing in different situations can help you regain clarity in your speech.
  3. Eating and chewing | Eating with your new teeth may require some adjustments as well. In the beginning, it’s advisable to start with a soft diet and gradually introduce firmer foods as you gain confidence and comfort. Chewing patterns may need to be modified initially, and it can take some time to develop a natural and efficient way of chewing with your new teeth.
  4. Follow-up visits and guidance | Our dentist will provide you with specific instructions on how to care for and use your new teeth. We will guide you on proper oral hygiene practices, dietary restrictions, and any necessary adjustments to ensure optimal function and comfort. Regular follow-up visits will let us assess your progress and provide additional guidance as needed.

Remember that each person’s experience and adaptation process can vary. With time, practice, and patience, you should become increasingly comfortable and proficient with using your new teeth. If you have any concerns or difficulties, do not hesitate to reach out to our office.

The procedure typically takes 3-4 hours per jaw.

No, you will not be able to remove your All-On-4 bridge(s) by yourself. Only a dentist can remove the bridge(s).

Yes, implants can fail and there are many factors that influence a failure. Infection, hygiene, medical conditions, smoking, diabetes, and neighboring tooth infection can all be major risk factors that contribute to an implant failing. It is recommended that you follow our post operative instructions to ensure that you do everything in your power to have a successful implant therapy.

Our digital approach using the latest technology allows us to adjust the design of your teeth to create multiple prototypes. If you wish to make changes to the design we can easily accommodate your preferences until you are satisfied with both the shape and color. It is important to keep in mind that once you agree on a design and your final teeth are fabricated you will not be able to change the shape/color free of charge.

Most people try to save money by flying throughout the continental United States or even to international clinics. We would caution against this because if something were to go wrong, such as teeth breaking or an implant not integrating, you would want to have your surgeon on call and available to fix it as soon as possible. Traveling abroad can often be more expensive compared to coming to our office, especially since our pricing is already less than the competition.

No they do not. Your All-On-4 bridges are rigidly attached to your implants, which are firmly anchored in your jaw. If your All-On-4 teeth begin rocking for any reason, call us so we can bring you in for an evaluation.

It is referred to as “Teeth In a Day” because you are receiving a set of functional prosthetic temporary teeth in one day. Because there are often major changes in your mouth during the healing and implant integration phase, it is best to start with temporary teeth. This ensures the best long-term outcome with your permanent teeth.

Yes. Your temporary teeth are made of acrylic and can chip, crack, and occasionally break. A great benefit of acrylic temporary is that it can easily be repaired. If you have any issues with your temporaries, just give us a call and we’ll get you fixed up right away.

While it is possible for zirconia to be damaged, it is extremely uncommon. Zirconia is amongst the strongest and most durable materials available in the dental world.

Unfortunately, no. We cannot use your existing implants and they will most likely need to be removed. The reasoning is twofold:

  1. Your existing implants will not be the correct position that the All-On-4 procedure requires
  2. Bone grafting will likely need to be performed

Have a question that hasn’t been answered? Give us a call!

All-On-4 Dental Implants Step by Step

The procedure itself typically takes 4-6 hours depending on whether you are having a single arch treated (upper or lower) or both arches (full mouth). When you leave our office, your temporary All-On-4 bridge(s) will be securely attached to your new implants.

You will wear your temporary bridge(s) for about 4 months to allow time for your implants to integrate with your bone and for your jaw and gums to heal into a stable, long-term position before we fabricate your final bridge(s). This healing time ensures the closest possible fit for your final bridges.

After you have healed, we will begin fabricating your final All-On-4 bridge(s). This involves a few appointments over a 5-6 week period, during which time you’ll help us design your ideal smile for your permanent teeth.

Digital Impressions
Our lab uses the latest technology to capture complete digital impressions of your mouth. We use these to make your temporary implant bridge(s). Possible wax try-in – if you are missing all or most of the teeth in the arch that we will be treating, our doctor may suggest a wax try-in. This is a mockup of your temporary implant bridge and will be used to check bite position, aesthetics, etc.
Digital Impressions
Procedure
Remove teeth (if applicable), place implants, and place temporary implant bridge(s). The procedure typically takes about 4-6 hours.
Procedure
Post Op #1
Day after procedure | Check in on your healing and answer any questions you may have.
Post Op #1
Post Op #2
3 weeks after procedure | Remove sutures and check healing. Patient is typically cleared to use a water flosser/WaterPik at this appointment.
Post Op #2
Impressions for Final Teeth
4 months after procedure | Take impressions for final All-On-4 zirconia bridges.
Impressions for Final Teeth
Try-In
5-10 days after impressions | We’ll “try-in” a mock-up of your final All-On-4 teeth. In some cases, multiple wax try-ins are needed. We want to make sure you’re completely happy with your wax try-ins before processing them because once they’re processed, we’re unable to make changes. If you want to make changes after you have approved your final bridge(s) and they’ve been fabricated, there will be a full-cost remake charge.
Try-In
Seat Final Teeth
4-6 weeks after try-ins | Your final All-On-4 teeth are ready to seat.
Seat Final Teeth