Should I be concerned about Dental Occlusion / Anterior Guidance? Part II
This is Part 2, the final part of our article to provide you with a better understanding about anterior guidance and how your bite works. We shall continue to attempt to explain in plain and simple terms what a dentist does to design and rebuild your bite (occlusion).
To make occlusal therapy as easy as possible to understand, we’ll present you with some basic content using a generalized manner of focus. FYI, there is a multitude of research documentation and text book information available on this subject. However without four years of dental school, the reading may be challenging or confusing to comprehend.
Understanding what your dentist will do to design and improve your bite
We present 3 general rules.
There are 3 general rules to design your occlusion (anterior guidance) that are required for the creation of a functional bite. The goal is to create a masticatory system that will be efficient, effective and sustainable with the continual grinding of thousands of chewing cycles per day.
At Westcoast, we apply these 3 general rules of occlusion (anterior guidance) design to every filling, every crown and every full mouth rehabilitation case. We do this because a proper design will allow you to feel better from better function while preventing teeth, bite or jaw problems. When we see patients who require a full mouth rehabilitation, full mouth crowns or orthodontics for function, we start with gathering data. The process begins with a careful exam-evaluation of your unique existing bite. This includes special diagnostic testing, and a face-bow record with detailed models. All of which is forwarded on to our digital lab for precise analysis. Nowadays, we can achieve predictable results using the latest dental technologies.
The first general rule is to have even sided occlusal contacts. The masticatory muscles can generate a lot of pressure, often several hundred pounds of force per square centimeter. Having even bite contacts throughout the arch allows for proper force distribution. In general, when an overstressed tooth cannot take any more force, it can become loose, suffer a fracture or the root of a tooth becomes infected or diseased. When you lose one tooth, think of the added weight that goes to the adjacent teeth. In many Westcoast cases, we focus on making certain that teeth should have a even distribution of the forces when designing an occlusion (anterior guidance). Problems occur when one particular tooth takes the force of even one more tooth.
What are some of the dental problems that can occur if one tooth has too much force? Well, there are many and include teeth hyper-sensitivity, wear lines on the sides of the teeth, teeth mobility, teeth fractures, excessive wear and temporomandibular jaw joint (TMJ) pain. You may even see erosion on the front sides of the teeth with a receding gum-line known as “afraction”. If you have had any or several of these symptoms or signs, then you may have what we call occlusal disease, a degenerative dental disease in which your bite is causing you problems. Therefore having well dispersed and even contacts is a critical design detail.
It also means that precise contact points should be made in the proper zone on the chewing surface of the tooth. For people with dental implants this is even more critical and the design for loading forces should be positioned along the axis of the implant for the best disbursement of force.
Overall, clinical experience shows us that properly designed bites have fewer issues, in comparison to people with uneven and unbalanced forces on their teeth.
The second general rule for occlusion design is anterior guidance. “Anterior” means the front and “Guidance” is referring to how the front teeth are guided forward. This “guidance” occurs when the lower front teeth have the ability to slide forward against the back of the upper front teeth. Try closing your mouth and then finding your bite. Then try sliding your lower teeth forward about a centimeter. This is what we call anterior guidance.
In part 1 of this article, we talked about the features of canine and anterior guidance. How important it is, in allowing the distribution of forces on the back teeth. Canine and anterior guidance allows for immediate disclusion of molars and premolars. Especially, when you are making lateral or forward movements, such as, when you are chewing food.
Research shows that when the back teeth are relieved of pressure when the jaw is sliding forward, there are important mechanical benefits. Firstly, the jaw muscles significantly decrease activity which can prevent the overloading of teeth and reduce bruxism. Furthermore, the amount of force applied to the front teeth is greatly minimized. This actually is very favorable for preventing, or slowing down damage and excessive wear.
Another perspective to consider carefully is when you slide you teeth laterally, to one side. You are sliding on what we call your working side. Your teeth on the opposite side are known as the non-working side and should be free of contact. The problem with contacts on the non-working side is the action it produces. Specifically, it increases muscular activity and stress on the non-working teeth.
When a patient has multiple back teeth touching when sliding the lower jaw forward, the back teeth will grind over each other. This occurs with increased muscular force, we often see these patients with severe signs and symptoms of occlusal disease. Such as excessive wear, joint or muscle pain, fractured teeth or wear facets on the sides of their teeth.
The third general rule of occlusion design is to create unobstructed movement when in function. In essence what this means is, when you are eating your lower jaw doesn’t just move side to side. But rather it moves forward and then back to a resting position upon closure. This is called the envelope of function and everyone has a different type of functionality and there are also average types of movement.
If you happen to have no contact on your front teeth at rest (open bite) or your lower teeth overlap your upper teeth (under bite). You may realize obstructed movement when you are chewing.
There are two main reasons that can lead to obstructed movement. The first is related to the shape and position of the front teeth. The slopes on the back of the upper front teeth must allow the lower front teeth to slide over them. If the shape or length is not favorable, you might report being locked in or unable to open your mouth freely. This often creates a very uncomfortable feeling, as the teeth that do not allow sufficient space interfere with the sliding forward motion.
The second reason relates to not having canine or group function. In Part 1, of this article we defined canine function. As the best way in which the canines allow you to lift away your back teeth when you slide your lower teeth forward. If it’s a group of teeth, that allows you to slide and lift away your back teeth? This is the second best case scenario, known as group function. People who don’t have their canines or their canine are in the wrong position then there function may be obstructed. Vietnamese and other Asians may have a canine positioned too far forward and therefore not functioning. Extremely crowded teeth with the canines out of function may have this problem. Think of your mouth being locked in a position where none of your front teeth are able to raise up because the teeth are so locked together.
It can lead to thinning of the front teeth if you can’t raise them up naturally. If this occurs then you have to find a way to sit your teeth back at rest every time. This causes a scraping of the front teeth, which results in severe thinning out of the top edges. It can also potentially cause excessive wear on numerous other front teeth. In addition, it may cause other problems like teeth mobility, chipping, breakage of teeth and jaw or muscle pain.
The 3 golden rules of occlusion design (anterior guidance) are vitally important to ensure that you experience fewer dental emergencies, headaches and stress. By creating a dental bite that is free of interferences, muscle hyperactivity and posterior non-working contacts. In addition, to following and practicing the 3 golden rules! Westcoast dental lab will always utilize state of the art digital technologies to insure the highest quality outcome. Which is critically important, especially in complex restoration cases where aesthetics are priority one.
So what does a dentist do to fix a bad dental bite?
Here in Westcoast Vietnam, we’ll carefully exam, explore and evaluate your entire dental situation and we’ll create a restoration design to create an ideal bite. Models of your bite can be uploaded onto a software program and then simulations of what can be modified take place. Before any dental treatment begins, your dentist, technician and yourself must understand and agree to the treatment plan.
Digital Smile Design, a technique used by cosmetic dentists, is a great tool to use for fixing dental bites. This method helps the entire team know what the end result goals are.
Now that the diagnosis and reconstruction plan is detailed, we are ready to for the first of 5 dental visits. All visits have checks in which our 3 rules of occlusion are constantly checked.
If you are going to have a full mouth case done, the following outlines what is done at each appointment after careful design and planning.
Dental Appointment #1: Preparation of the teeth. We will prepare the stumps of the teeth in conservative manner in a cautious and gentle manner. Our goal is to minimize tooth preparation and to maintain the nerves of the teeth. This is done by making reduction guides and wax ups to know exactly how much to prepare. A local anesthetic is provided and you should be very comfortable during this session.
After the preparations have been scanned or impressed, our digital lab receives the information. We conclude with placing a temporary bridge that we’ll build in concurrence with our design plan.
Dental Appointment #2 A second temporary try in maybe done very shortly to verify the smile design and the occlusion (anterior guidance). This allows us to pretest the final teeth need to be modified in order to fulfill the exact design. During this stage we can tweak, amend and adjust our design to make sure the final fixture is as near perfect as possible.
Dental Appointment #3 After 3-7 days, our digital dental laboratory will have made the framework or nearly finished your new teeth. The goal at this appointment is to determine your entire movement functionality in a test or what we call a “try in stage”. This visit will test that all contacts are even, there is proper anterior guidance and absence of non working contacts and that your envelope of function is as planned. You will be very involved in the process and help us make final detail adjustments such as shape, surface texture and length. During this visit, we observe that you are free of obstruction, free of non-working contacts and the movement is on our model is replicated in the mouth.
This is the major step in the entire process to see that all the design work can be transferred and replicated into the mouth. If it is accurate it should feel ideal and the movements predictable from the use of advanced technical computer imaging and the articulation device.
These design steps are especially critical in dental veneer and full ceramic mouth cases. Veneers may crack, de-bond or chip when either of the 3 rules of occlusion design are violated.
Dental Appointment #4 Cementation or Bonding. A final checklist of all the criteria including the esthetic is carried out. The fit must be under 25 microns to ensure a very good outcome. Everything is carefully evaluated. Once approved, we cement or bond the restorations permanently. And of course, you also must be happy before, then we are ready for the final cementation or bonding of the new teeth into the mouth. There are times we can place them with temporary cement for a day in case you want to just try them in.
Dental Appointment #5 We review all the checklist criteria again. Small adjustments may or may not be required. On this appointment we likely have already agreed with you to wear a night guard at night time. We believe that after a full veneer or full ceramic case is completed, the best protection is to wear a night guard because if you had worn teeth from wear and tear before, we don’t want it to happen again!
And what did the Dental Lab do to ensure a good result? In our lab, we make three important group of determinations.
The first is to determine the ideal edge position for your front teeth, in order to do so we need to determine the length and inclination of the edges.
If your incisal edges are too far forward you will have speaking issues and it will also detract from your appearance. Poorly designed edges will interfere with your lip and certain words you speak for example, sexy teeth, will be impaired. Really, it’s true, “s” and “t” sounds may not come out the right way or the way you intended it to sound.
Also, if your incisal edges are too far backward, you may end up feeling locked in and therefore the envelope of function is obstructed.
The second most important determination our lab will have to consider is proper anterior guidance. We aim for the optimal shape of the back of the upper front teeth and fronts of the lower front teeth to be as much an ideal shape in an interlocking sloping relationship. This must be considered carefully to allow for the best steepness in rise.
This particular design has to be done on a fully adjusted articulator to mimic your own exact jaw movements. The steepness of the front teeth is most ideal when it matches the angle of movement that your jaw joint naturally allows and follows.
The dentist and dental technician will design and shape the fitting of the front teeth in a concave manner. This is done, so that no interference to the anterior path of closure will occur.
If this rule is violated when constructing front teeth, patients will complain that their bite feels high, locked in or they can’t chew through an apple comfortably.
Finally, the lab has fulfilled your dentist and your request for color, surface texture, length, shape and other personal characteristics to make your smile and teeth look natural and beautiful.
At Westcoast each and every case is unique and it is our mission, desire and ultimate goal to create the most optimal occlusion design as possible. Using our own in house lab we can control and deliver outcomes efficiently and effectively.