October 13, 2025 • 20 mins
Focuses on the complex masticatory system and the principles of "complete dentistry". The text emphasizes the critical importance of a stable and harmonious relationship between the temporomandibular joints (TMJs), the masticatory muscles, and the occluding surfaces of the teeth for optimal oral health. It covers diagnostic procedures like centric relation determination and load testing, discusses various occlusal disorders such as wear and pain, and details treatment modalities including occlusal equilibration, splint therapy, and restorative techniques. Furthermore, the author advocates for programmed treatment planning and cautions against relying on symptoms alone, stressing the need to address the underlying causative factors of dental instability.
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Speaker 1 (00:00):
Welcome back to the deep dive. Today, we're tackling a
really significant text in dentistry, functional occlusion from TMJ to
Smile Design.
Speaker 2 (00:08):
Yeah, it's foundational stuff absolutely.
Speaker 1 (00:10):
Our mission today is to give you our listeners, whether
you're a clinician, a student, or just really interested, a
full detailed summary of its core ideas. Think of it
as the expert shortcut.
Speaker 2 (00:23):
That's a good way to put it, because this book
isn't just about fixing a tooth here or there. It's
about understanding the whole system, the mastigatory system, and it
argues pretty strongly that the only way to get predictable,
long lasting results is to follow a complete philosophy with
the authors called complete dentistry.
Speaker 1 (00:42):
Okay, so complete dentistry. What does that actually involve? What
are the big goals they set out?
Speaker 2 (00:47):
Well, there are five key requirements and they have to
happen in sequence. First, you need optimal oral health. That's basic,
makes sense. Then anatomic harmony, followed by functional harmony, and
this is crucial. Orthopedic sty that's.
Speaker 1 (01:00):
The big one, orthopedic stability.
Speaker 2 (01:02):
Yeah. Only after you've nailed those four can you really
predictably achieve you know, natural looking aesthetics health first, stability second,
looks last.
Speaker 1 (01:13):
I like that hierarchy. It really changes the game, doesn't it.
It shifts the dentist from just being like a tooth
mechanic exactly.
Speaker 2 (01:20):
The core idea, the whole premise is that today's dentist
needs to be a physician of the masticatory system.
Speaker 1 (01:26):
Physician of the masticatory system.
Speaker 2 (01:28):
Wow. And that means predictable results come from prioritizing function,
optimal function and stability. You just can't chase aesthetics if
it messes up the function. That's a recipe for problems
down the line.
Speaker 1 (01:39):
Which brings U straight to causality. Right. If stability is
the goal, we need to know what causes instability precisely.
Speaker 2 (01:46):
The book really emphasizes that dental problems are rarely caused
by just one thing. It's usually a mix multi causality.
Speaker 1 (01:52):
So like where patterns or muscle pain could stem from
different issues exactly.
Speaker 2 (01:57):
You could see similar symptoms, but the underlying causes might
be totally different. Or conversely, one small issue, maybe a
tiny interference on a molar, could cause a whole range
of different symptoms in different people.
Speaker 1 (02:08):
And that's why the book says, treating just the symptoms
is and I quote short sighted therapy. Why is just
chasing the pain such a flawed approach.
Speaker 2 (02:17):
Well, it's flawed because you haven't dealt with the actual
source of the problem. If the root cause is, say
a clusal overload, a tooth getting hit wrong or too hard,
just managing the pain doesn't stop that overload. Uh So
the problem just comes back or maybe gets worse or
shift somewhere else. The focus has to be on finding
that primary cause and getting rid of it. Then the
(02:39):
body can often adapt and heal itself.
Speaker 1 (02:41):
Okay, So if we accept this idea of multiple causes,
where does the book tell us to begin our investigation?
It seems like it always comes back to the joints,
the TMJs.
Speaker 2 (02:50):
Absolutely, it's fundamental. You cannot The book stresses evaluate or
fix how the teeth bite together without first making sure
the TMJs are in harmony. They literally say, there is
no such thing as a perfect occlusion with a displaced TMJ.
If the joints aren't stable, the bite won't be stable either,
simple as that.
Speaker 1 (03:08):
And structurally, people often misunderstand the TMJ, don't they. It's
built to handble serious force.
Speaker 2 (03:14):
Oh, Yeah, it's a powerhouse. It's designed as a true
load bearing joint. It can handle hundreds of pounds of force.
Speaker 1 (03:21):
How does it do that without causing pain?
Speaker 2 (03:24):
It's all about where the load goes. It has to
be directed through a specific part of the disk inside
the joint, the load bearing zone. This area has no blood,
vessels or nerves. It's a vascular and non enervated ah.
Speaker 1 (03:35):
So it can take the pressure exactly.
Speaker 2 (03:38):
As long as the end of the jawbone, the condyle,
and that disc are lined up correctly in that zone,
the joint can take the load comfortably. Pain usually means
things are misaligned and the pressure is hitting tissues with nerves.
Speaker 1 (03:50):
Okay, that makes sense, and that perfectly sets up the
absolute cornerstone concept centric relation CR. How do we define
that position precisely? Because it sounds critical?
Speaker 2 (04:00):
Oh, it is. The definition is something you just have
to know. Cold centric relation or CR is the relationship
of the lower jaw mandible to the upper jaw macella.
When the properly aligned condyle disc assemblies are in the
most superior position possible against the bony slopes in front
of them, the.
Speaker 1 (04:17):
Eminenci most superior got it, and.
Speaker 2 (04:19):
This position doesn't depend on how open or close the
jaw is vertically or where the teeth happened to touch.
It's a structural position and crucially, it's also braced medially
towards the mill, meaning it's the midmost position too, superior
and medial.
Speaker 1 (04:35):
That sounds very specific. Why can't a patient just you know,
bite down where it feels natural to find CR?
Speaker 2 (04:41):
Good question. It's because of muscle memory, what we call
habitual closure or convenience closure. See CR itself is incredibly stable,
precisely repeatable to within needle point accuracy. The book says, wow.
But if a patient has interferences like a high filling,
their muscles learned to bite slightly off that idea spot
to avoid hitting it, usually a bit forward and down.
Speaker 1 (05:03):
So they develop a habit that avoids the interference, but
isn't truly CR exactly.
Speaker 2 (05:08):
So we need a technique to gently guide the jaw
past that muscle memory and find the true structurally determined
CR position.
Speaker 1 (05:14):
And that's where the hands on technique, the bilateral manipulation,
comes in. Can you walk us through that?
Speaker 2 (05:19):
Sure? The goal is to seat the condole disc assembly
fully up and back without the teeth getting in the way.
Typically the patient is lying back supine, chin up to
help relax the muscles. Okay, The clinician uses their thumbs
on the lower front tee to keep them slightly apart
while the fingers wrap around the angle of the jaw.
Then you apply firm but gentle at first upward pressure
(05:40):
through the condoles bilaterally both sides at once.
Speaker 1 (05:43):
Firm upward pressure, yeah.
Speaker 2 (05:44):
Guiding the condoles up the posterior slopes of the eminenci.
You might need to gradually increase the pressure to overcome
any muscle resistance, guiding it into that most superior position.
Speaker 1 (05:54):
And then comes the ultimate check, the absolute non negotiable.
According to the text the low test.
Speaker 2 (06:00):
Yes, this is probably the single most important diagnostic step
in this whole philosophy. The principle is simple but powerful.
If the temporal mandibular joints TMJ's are not completely comfortable
when firmly loaded, they are not in centric relation.
Speaker 1 (06:14):
So if you load the joint in what you think
is CR and the patient feels any pain or even
just tension.
Speaker 2 (06:21):
It's not CR, or at least it's not a stable CR.
It means the forces are hitting those sensitive innervated tissues
behind the disc, or there's some kind of internal joint
problem that makes it unstable underload. Comfort underload equal stability.
Speaker 1 (06:35):
But the system isn't totally rigid, right. It talks about
adapted centric posture ACP. What if a joint has been
damaged in the past, is stability still achievable?
Speaker 2 (06:45):
Yes, and that's important. ACP acknowledges that sometimes joints get
deformed due to past injuries or disorders inside the capsule. Yeah,
they might not look perfect on an X ray, Okay,
but if that adapted joint meets specific criteria, essentially the
conal is still seated as high as possible, it's braced medially,
and crucially it passes the load test with zero tension
(07:06):
or tenderness.
Speaker 1 (07:07):
Ah. The load test again.
Speaker 2 (07:08):
Always the load test. If it's comfortable underload, even if
it's structurally compromised, we can consider that an adapted centric
posture and use it as a stable reference point for treatment.
But bottom line, unstable joints always lead to unstable bytes period.
Speaker 1 (07:22):
That clarity is so important, which leads us nicely into diagnosis.
The text is pretty critical of how the scientific literature
often lumps all jaw, joint and muscle pain together as
just TMD.
Speaker 2 (07:32):
Yeah, it argues that treating temporal mandibular disorders TMD as
one single thing is a huge mistake. It leads to
confusing research and frankly bad clinical decisions.
Speaker 1 (07:43):
So how should we classify these problems for practical diagnosis?
Speaker 2 (07:47):
The book proposes a very useful distinction, separating problems into
acluso muscle disorders or OMD and intracapsular disorders ICD problems
primarily in the muscles, versus problems primarily inside the joint
capsule itself.
Speaker 1 (08:00):
Let's start with OMD aclusove muscle disorders. If the pain
is muscular, where's it actually coming from?
Speaker 2 (08:06):
Generally, the pain in OMD originates in the big chewing muscles,
the massiter, the temporallis, and it's usually triggered by deflective
occlusal interferences.
Speaker 1 (08:15):
Like that high filling example.
Speaker 2 (08:16):
Again, exactly if a patient bites down and hits a
high spot or a steep incline on a bag tooth, first,
the brain tells those elevator muscles to work overtime, to
become hyperactive, trying to avoid damage or find a more
stable position. Research like Williamson's work with EMG actually measured
this increased muscle activity caused directly by the interference.
Speaker 1 (08:38):
Okay, so muscle hyperactivity triggered by the bite. How do
we test for that clinically? How do we know it's
OMD and not something deeper inside the joint?
Speaker 2 (08:48):
We use what's called the anterior deprogramming test. It's simple
but very effective. You place something between the front teeth
to keep the back teeth completely separated. A flat biplane
or often even just a cotton roll across the will
do it.
Speaker 1 (09:00):
And what does separating the back teeth achieve?
Speaker 2 (09:03):
It does two key things. First, it allows the condoles
to seat fully upward into cr unhindered by tooth contacts. Second,
and this is critical, it releases the contraction of the
muscles that pull the jaw forward, specifically the inferior lateral teriagoids.
If separating the posterior teeth causes the patient's muscle pain
to decrease significantly or even disappear almost immediately, that strongly
(09:24):
suggests OMD is the main issue. The interference was triggering
the muscle problem.
Speaker 1 (09:29):
Which logically means if you do that test, separate the
teeth and the pain doesn't get better, or maybe it
even gets worse.
Speaker 2 (09:36):
Exactly, then you should strongly suspect an intracapsular disorder and
ICD a problem inside the joint itself.
Speaker 1 (09:43):
Why would separating the teeth make an internal joint problem worse?
Speaker 2 (09:47):
Because if you have, say, an unstable or displaced disc
inside the joint, what we call internal derangement, putting that
anterior dprogrammer in allows the condele to seat further up.
But if the disc isn't in the right place, seating
the condyle fully just increases the pressure on painful, inflamed
or misaligned tissues within the joy capsule.
Speaker 1 (10:06):
So pain increases under that upward pressure when the teeth
are apart. That points towards ICD.
Speaker 2 (10:11):
Precisely, it's a powerful differential diagnostic tool. Pain relief points
to OMD, pain increase points to ICD.
Speaker 1 (10:17):
Okay, fantastic diagnostic logic. Now let's shift gears into treatment principles.
The book seems particularly forceful about debunking myths around the
vertical dimension of occlusion or vdo.
Speaker 2 (10:30):
Oh. Absolutely, it's very clear on this. The biggest misconception
is that comfort dictates the correct vido.
Speaker 1 (10:36):
People think if the patient feels okay at a certain
jaw opening, that must be the right VIDO.
Speaker 2 (10:41):
Yes, and the book states unequivocally comfort is not a
determinant of correct video. You can make patients comfortable at
almost any vertical dimension, whether you open it or close
it quite a bit.
Speaker 1 (10:53):
So if comfort isn't the guide, what does determine the
physiologically correct video.
Speaker 2 (10:57):
It's determined by the biology of the muscles, specifically the
repetitive contracted length of the elevator muscles. The muscles that
close the jaw have a sort of programmed resting length,
and that dictates the video.
Speaker 1 (11:08):
Wow, okay, that's a major point. So what's the clinical implication.
If we're doing big restorative cases Crowns bridges, the.
Speaker 2 (11:15):
Implication is huge. You should generally aim to treat the
patient as close to their original existing video as possible,
because the muscles are already adapted to that length.
Speaker 1 (11:23):
And changing it significantly requires.
Speaker 2 (11:26):
It requires significant edipation time, especially increasing the video. If
you increase it beyond the muscle's natural contracted length, you're
asking those muscles to adapt to a permanently stretched position,
which can lead to fatigue. Discomfort, maybe even instability down
the road stick close to the original VBO whenever feasible.
Speaker 1 (11:46):
Got it. So, after we've established a stable CR foundation,
the next pillar seems to be anterior guidance.
Speaker 2 (11:52):
Correct. Once CR is stable the way the front teeth
guide the jaw during movement, the anterior guidance becomes the
dominant actor determine how the back teeth should be shaped
in function second only to CR itself, and it needs.
Speaker 1 (12:06):
To be in harmony with something called the envelope of function.
Speaker 2 (12:08):
Yes, the envelope function just refers to the natural programmed
pathway as the lower jaw follows during chewing, speaking swallowing,
the interior guidance needs to allow those movements smoothly without interference.
Speaker 1 (12:20):
The book uses a really elegant phrase to summarize the
goal dots in back, lines in front. Can you unpack
that for us?
Speaker 2 (12:27):
It's brilliant, isn't it.
Speaker 1 (12:28):
Dots in back means when the jaw is fully seated
in centric relation, all the posterior teeth should contact simultaneously
and evenly, creating stable pinpoint stops.
Speaker 2 (12:40):
Just dots, stable holding contacts in CR okay and lines
in front.
Speaker 1 (12:45):
Lines in front refers to eccentric movements when the jaw
moves forward protrusive or sideways lateral. As soon as the
jaw starts to move out of cr the anterior teeth,
incisors and canines should immediately contact and smoothly guide the
movement cause, using all the posterior teeth to separate instantly disclusion.
Speaker 2 (13:03):
Immediate posterior disclusion. Why is that separation so critical.
Speaker 1 (13:07):
Because it shuts down that muscle hyperactivity we talked about earlier.
Remember Williamson's EMG studies. If back teeth rub against each
other during side to side or forward movements, those powerful
elevator muscles firelight crazy.
Speaker 2 (13:19):
Okay.
Speaker 1 (13:19):
The anterior guidance acts like a circuit brigger. It protects
the posterior teeth from damaging lateral forces and keeps the
muscles quiet during eccentric movements. It's essential for comfort and
preventing wear or mobility. Makes perfect sense. And what about
the actual shape the form of the posterior teeth themselves.
What's needed for stability there?
Speaker 2 (13:38):
The main thing is directing forces down the long axis
of the tooth. Generally this means having the buckle cusps
the ones towards the cheek of the lower teeth fitting
neatly into the central fosa. The grooves of the upper
teeth stamp cusp into fosa.
Speaker 1 (13:54):
Okay, and the book specifically rejects a concept called bilaterally
balanced a clue for natural teeth. Why is that? I
know some schools used to teach that.
Speaker 2 (14:03):
Yeah, it was a concept bard from denture construction. Bilateral
balance means having posterior teeth on both sides contacting during
lateral movements. The book argues this as harmful for natural teeth.
Way harmful because those working in non working side interferences
during lateral movement generates significant lateral stress, especially against the
orbiting condyle, which isn't braced. This leads to things like
(14:24):
tooth mobility, excessive wear, and even periodontal breakdown. It creates
the exact muscle hyperactivity and damaging forces that proper anterior
guidance aims to eliminate. It's just not physiologically sound for
natural dentition.
Speaker 1 (14:38):
Okay, that's a clear rejection. So putting this all together
for complex cases, the book outlines program treatment planning, or PTP.
How does that help avoid guesswork?
Speaker 2 (14:48):
PTP is basically a systematic approach. It forces you to
check if those five requirements for stability, stable joints, muscle comfort, CR, MIP, coincidence,
anterior guidance, poster your ustability are met before you start
irreversible treatment.
Speaker 1 (15:03):
So you diagnose based on those.
Speaker 2 (15:05):
Five requirements exactly. You find the deficits, and based on
what's missing, your treatment options fall into logical categories. Reshape
the existing teeth, maybe reposition them orthodonically, restore them with
crowns or fillings, or sometimes surgery is needed for the
jaws or joints. It's a structured thought process, ensuring the
foundation is solid before you build the house, so to speak.
Speaker 1 (15:25):
I like that analogy, and the simplest form of reshaping
is often a clusal equilibration adjusting the bite. The text
gives that famous Mudl rule for eliminating interferences that prevent
CR closure.
Speaker 2 (15:36):
Yes, and when done correctly, equilibration based on CR is
incredibly predictable. The Medl rule is a lifesaver for figuring
out which incline to adjust on a tooth that's interfering
as a jaw closes into CR.
Speaker 1 (15:50):
Remind us what MEDL stands for me.
Speaker 2 (15:52):
Seal inclines of upper teeth or the distal inclines of
lower teeth. These are the specific inclines that, if they
hit prematurely, tend to deflect the mandible forward out of
cr So you adjust those specific inclines. Genius little rule.
Speaker 1 (16:07):
That is handy. Now, another really interesting point the book
makes is about severe wear. It argues that attritional wear
the kind from grinding or clenching rxism. It argues that
even severe wear from bruxism does not cause a loss
of video.
Speaker 2 (16:19):
That seems counterintuitive it does, but the explanation makes sense.
Attritional wear only happens if teeth are actually rubbing against
each other, meaning they are in the way during jaw movements.
But crucially, as the tooth structure wears down, the teeth
continuously erupts slightly to maintain contact and preserve that vertical
dimensions set by the muscles.
Speaker 1 (16:38):
So the teeth erupt to compensate for the wear, keeping
the vdo constant.
Speaker 2 (16:42):
Essentially, Yes, now, this is very different from erosion. Erosion
is chemical wear, maybe from acid reflux or ascetic drinks.
You know, that causes a different pattern, often dished out
lesions and can lead to VDO loss because it's dissolving
tooth structure independent of the occlusal function and eruption mechanism,
where versus erosion very different causes and effects on video.
Speaker 1 (17:04):
That distinction is critical. Okay, last major point we have
to touch on the critique of neuromuscular dentistry NMD. It's
a controversial topic. What's the book's main issue with the
NMD approach?
Speaker 2 (17:14):
The core criticism revolves around how NMD determines the treatment position.
NMD typically uses low frequency to ns like a mile monitor,
to relax the muscles and then find a byte position
based on where those relaxed muscles want the jaw to be.
Speaker 1 (17:29):
Okay, what's the problem with that?
Speaker 2 (17:30):
The problem is that this position derived electronically often results
in the condos being positioned significantly forward and downward compared
to centric relation, and achieving this often requires artificially increasing the.
Speaker 1 (17:41):
Video and functionally. Why is that forward downward position considered
unstable according to this philosophy because.
Speaker 2 (17:49):
To close into that forward NMD position, the muscles that
pull the jaw forward, the inferior lateral tarygoids have to
remain active, constantly fighting against the powerful elevator muscles that
are trying to the condoles back and up into cr AH.
Speaker 1 (18:03):
So it creates muscle conflict exactly.
Speaker 2 (18:05):
It sets up this chronic muscle in coordination. This isometric
battle between muscle groups. That's the very thing that a
functionally sound occlusion based on CR aims to eliminate. A
key requirement for CR is the timely release of those
forward pulling muscles as the jaw seats allowing the elevators
to close fully and rest. The NMD position often prevents
(18:28):
that release.
Speaker 1 (18:29):
That's a fundamental disagreement in philosophy and physiology right there.
Speaker 2 (18:32):
It really is.
Speaker 1 (18:33):
Wow. Okay, this has been an incredibly thorough journey through
the core principles of functional occlusion. If you had to
boil it down, what's the single biggest takeaway for someone listening.
Speaker 2 (18:42):
I think it's understanding the inner deependency, the TMJ, the muscles,
the teeth, they're all linked by following this kind of
sequential system based approach, stable joins first, then relaxed muscles,
then a harmonious bite built on that foundation, you take
the guess work out of it. Predictability, predictability, comfort, and
(19:03):
long term stability. That's the goal. Even if the final
result isn't a perfect textbook classiecclusion, if it's stable and
comfortable for that patient based on their physiology, that's success.
Stability Trump's idealized aesthetics every time.
Speaker 1 (19:17):
Stability is the goal. Love it, and maybe one final
thought to leave everyone chewing on, so to speak. Think
about the power of that load test. It really is
the gatekeeper verifying joint stability under load before you make
any permanent changes to the bite. That's the step that
underpins everything else.
Speaker 2 (19:33):
Couldn't agree more, and it helps solidify some of these
key diagnostic ideas. Maybe we can offer a little review exercise.
Speaker 1 (19:39):
Great idea, Okay, here it is for you to think
about review exercise. Imagine you have a patient presenting with
jaw muscle pain. You suspect it might be related to
a deflective interference on a back tooth design. The two
key clinical tests you had performed to confirm this diagnosis
and differentiate it from an intracapsular disorder a problem inside
the joint, make sure you state the expected outcome for
(20:01):
each test. If the problem is purely an inclusive muscle
disorder OMD,
Welcome back to the deep dive. Today, we're tackling a
really significant text in dentistry, functional occlusion from TMJ to
Smile Design.
Speaker 2 (00:08):
Yeah, it's foundational stuff absolutely.
Speaker 1 (00:10):
Our mission today is to give you our listeners, whether
you're a clinician, a student, or just really interested, a
full detailed summary of its core ideas. Think of it
as the expert shortcut.
Speaker 2 (00:23):
That's a good way to put it, because this book
isn't just about fixing a tooth here or there. It's
about understanding the whole system, the mastigatory system, and it
argues pretty strongly that the only way to get predictable,
long lasting results is to follow a complete philosophy with
the authors called complete dentistry.
Speaker 1 (00:42):
Okay, so complete dentistry. What does that actually involve? What
are the big goals they set out?
Speaker 2 (00:47):
Well, there are five key requirements and they have to
happen in sequence. First, you need optimal oral health. That's basic,
makes sense. Then anatomic harmony, followed by functional harmony, and
this is crucial. Orthopedic sty that's.
Speaker 1 (01:00):
The big one, orthopedic stability.
Speaker 2 (01:02):
Yeah. Only after you've nailed those four can you really
predictably achieve you know, natural looking aesthetics health first, stability second,
looks last.
Speaker 1 (01:13):
I like that hierarchy. It really changes the game, doesn't it.
It shifts the dentist from just being like a tooth
mechanic exactly.
Speaker 2 (01:20):
The core idea, the whole premise is that today's dentist
needs to be a physician of the masticatory system.
Speaker 1 (01:26):
Physician of the masticatory system.
Speaker 2 (01:28):
Wow. And that means predictable results come from prioritizing function,
optimal function and stability. You just can't chase aesthetics if
it messes up the function. That's a recipe for problems
down the line.
Speaker 1 (01:39):
Which brings U straight to causality. Right. If stability is
the goal, we need to know what causes instability precisely.
Speaker 2 (01:46):
The book really emphasizes that dental problems are rarely caused
by just one thing. It's usually a mix multi causality.
Speaker 1 (01:52):
So like where patterns or muscle pain could stem from
different issues exactly.
Speaker 2 (01:57):
You could see similar symptoms, but the underlying causes might
be totally different. Or conversely, one small issue, maybe a
tiny interference on a molar, could cause a whole range
of different symptoms in different people.
Speaker 1 (02:08):
And that's why the book says, treating just the symptoms
is and I quote short sighted therapy. Why is just
chasing the pain such a flawed approach.
Speaker 2 (02:17):
Well, it's flawed because you haven't dealt with the actual
source of the problem. If the root cause is, say
a clusal overload, a tooth getting hit wrong or too hard,
just managing the pain doesn't stop that overload. Uh So
the problem just comes back or maybe gets worse or
shift somewhere else. The focus has to be on finding
that primary cause and getting rid of it. Then the
(02:39):
body can often adapt and heal itself.
Speaker 1 (02:41):
Okay, So if we accept this idea of multiple causes,
where does the book tell us to begin our investigation?
It seems like it always comes back to the joints,
the TMJs.
Speaker 2 (02:50):
Absolutely, it's fundamental. You cannot The book stresses evaluate or
fix how the teeth bite together without first making sure
the TMJs are in harmony. They literally say, there is
no such thing as a perfect occlusion with a displaced TMJ.
If the joints aren't stable, the bite won't be stable either,
simple as that.
Speaker 1 (03:08):
And structurally, people often misunderstand the TMJ, don't they. It's
built to handble serious force.
Speaker 2 (03:14):
Oh, Yeah, it's a powerhouse. It's designed as a true
load bearing joint. It can handle hundreds of pounds of force.
Speaker 1 (03:21):
How does it do that without causing pain?
Speaker 2 (03:24):
It's all about where the load goes. It has to
be directed through a specific part of the disk inside
the joint, the load bearing zone. This area has no blood,
vessels or nerves. It's a vascular and non enervated ah.
Speaker 1 (03:35):
So it can take the pressure exactly.
Speaker 2 (03:38):
As long as the end of the jawbone, the condyle,
and that disc are lined up correctly in that zone,
the joint can take the load comfortably. Pain usually means
things are misaligned and the pressure is hitting tissues with nerves.
Speaker 1 (03:50):
Okay, that makes sense, and that perfectly sets up the
absolute cornerstone concept centric relation CR. How do we define
that position precisely? Because it sounds critical?
Speaker 2 (04:00):
Oh, it is. The definition is something you just have
to know. Cold centric relation or CR is the relationship
of the lower jaw mandible to the upper jaw macella.
When the properly aligned condyle disc assemblies are in the
most superior position possible against the bony slopes in front
of them, the.
Speaker 1 (04:17):
Eminenci most superior got it, and.
Speaker 2 (04:19):
This position doesn't depend on how open or close the
jaw is vertically or where the teeth happened to touch.
It's a structural position and crucially, it's also braced medially
towards the mill, meaning it's the midmost position too, superior
and medial.
Speaker 1 (04:35):
That sounds very specific. Why can't a patient just you know,
bite down where it feels natural to find CR?
Speaker 2 (04:41):
Good question. It's because of muscle memory, what we call
habitual closure or convenience closure. See CR itself is incredibly stable,
precisely repeatable to within needle point accuracy. The book says, wow.
But if a patient has interferences like a high filling,
their muscles learned to bite slightly off that idea spot
to avoid hitting it, usually a bit forward and down.
Speaker 1 (05:03):
So they develop a habit that avoids the interference, but
isn't truly CR exactly.
Speaker 2 (05:08):
So we need a technique to gently guide the jaw
past that muscle memory and find the true structurally determined
CR position.
Speaker 1 (05:14):
And that's where the hands on technique, the bilateral manipulation,
comes in. Can you walk us through that?
Speaker 2 (05:19):
Sure? The goal is to seat the condole disc assembly
fully up and back without the teeth getting in the way.
Typically the patient is lying back supine, chin up to
help relax the muscles. Okay, The clinician uses their thumbs
on the lower front tee to keep them slightly apart
while the fingers wrap around the angle of the jaw.
Then you apply firm but gentle at first upward pressure
(05:40):
through the condoles bilaterally both sides at once.
Speaker 1 (05:43):
Firm upward pressure, yeah.
Speaker 2 (05:44):
Guiding the condoles up the posterior slopes of the eminenci.
You might need to gradually increase the pressure to overcome
any muscle resistance, guiding it into that most superior position.
Speaker 1 (05:54):
And then comes the ultimate check, the absolute non negotiable.
According to the text the low test.
Speaker 2 (06:00):
Yes, this is probably the single most important diagnostic step
in this whole philosophy. The principle is simple but powerful.
If the temporal mandibular joints TMJ's are not completely comfortable
when firmly loaded, they are not in centric relation.
Speaker 1 (06:14):
So if you load the joint in what you think
is CR and the patient feels any pain or even
just tension.
Speaker 2 (06:21):
It's not CR, or at least it's not a stable CR.
It means the forces are hitting those sensitive innervated tissues
behind the disc, or there's some kind of internal joint
problem that makes it unstable underload. Comfort underload equal stability.
Speaker 1 (06:35):
But the system isn't totally rigid, right. It talks about
adapted centric posture ACP. What if a joint has been
damaged in the past, is stability still achievable?
Speaker 2 (06:45):
Yes, and that's important. ACP acknowledges that sometimes joints get
deformed due to past injuries or disorders inside the capsule. Yeah,
they might not look perfect on an X ray, Okay,
but if that adapted joint meets specific criteria, essentially the
conal is still seated as high as possible, it's braced medially,
and crucially it passes the load test with zero tension
(07:06):
or tenderness.
Speaker 1 (07:07):
Ah. The load test again.
Speaker 2 (07:08):
Always the load test. If it's comfortable underload, even if
it's structurally compromised, we can consider that an adapted centric
posture and use it as a stable reference point for treatment.
But bottom line, unstable joints always lead to unstable bytes period.
Speaker 1 (07:22):
That clarity is so important, which leads us nicely into diagnosis.
The text is pretty critical of how the scientific literature
often lumps all jaw, joint and muscle pain together as
just TMD.
Speaker 2 (07:32):
Yeah, it argues that treating temporal mandibular disorders TMD as
one single thing is a huge mistake. It leads to
confusing research and frankly bad clinical decisions.
Speaker 1 (07:43):
So how should we classify these problems for practical diagnosis?
Speaker 2 (07:47):
The book proposes a very useful distinction, separating problems into
acluso muscle disorders or OMD and intracapsular disorders ICD problems
primarily in the muscles, versus problems primarily inside the joint
capsule itself.
Speaker 1 (08:00):
Let's start with OMD aclusove muscle disorders. If the pain
is muscular, where's it actually coming from?
Speaker 2 (08:06):
Generally, the pain in OMD originates in the big chewing muscles,
the massiter, the temporallis, and it's usually triggered by deflective
occlusal interferences.
Speaker 1 (08:15):
Like that high filling example.
Speaker 2 (08:16):
Again, exactly if a patient bites down and hits a
high spot or a steep incline on a bag tooth, first,
the brain tells those elevator muscles to work overtime, to
become hyperactive, trying to avoid damage or find a more
stable position. Research like Williamson's work with EMG actually measured
this increased muscle activity caused directly by the interference.
Speaker 1 (08:38):
Okay, so muscle hyperactivity triggered by the bite. How do
we test for that clinically? How do we know it's
OMD and not something deeper inside the joint?
Speaker 2 (08:48):
We use what's called the anterior deprogramming test. It's simple
but very effective. You place something between the front teeth
to keep the back teeth completely separated. A flat biplane
or often even just a cotton roll across the will
do it.
Speaker 1 (09:00):
And what does separating the back teeth achieve?
Speaker 2 (09:03):
It does two key things. First, it allows the condoles
to seat fully upward into cr unhindered by tooth contacts. Second,
and this is critical, it releases the contraction of the
muscles that pull the jaw forward, specifically the inferior lateral teriagoids.
If separating the posterior teeth causes the patient's muscle pain
to decrease significantly or even disappear almost immediately, that strongly
(09:24):
suggests OMD is the main issue. The interference was triggering
the muscle problem.
Speaker 1 (09:29):
Which logically means if you do that test, separate the
teeth and the pain doesn't get better, or maybe it
even gets worse.
Speaker 2 (09:36):
Exactly, then you should strongly suspect an intracapsular disorder and
ICD a problem inside the joint itself.
Speaker 1 (09:43):
Why would separating the teeth make an internal joint problem worse?
Speaker 2 (09:47):
Because if you have, say, an unstable or displaced disc
inside the joint, what we call internal derangement, putting that
anterior dprogrammer in allows the condele to seat further up.
But if the disc isn't in the right place, seating
the condyle fully just increases the pressure on painful, inflamed
or misaligned tissues within the joy capsule.
Speaker 1 (10:06):
So pain increases under that upward pressure when the teeth
are apart. That points towards ICD.
Speaker 2 (10:11):
Precisely, it's a powerful differential diagnostic tool. Pain relief points
to OMD, pain increase points to ICD.
Speaker 1 (10:17):
Okay, fantastic diagnostic logic. Now let's shift gears into treatment principles.
The book seems particularly forceful about debunking myths around the
vertical dimension of occlusion or vdo.
Speaker 2 (10:30):
Oh. Absolutely, it's very clear on this. The biggest misconception
is that comfort dictates the correct vido.
Speaker 1 (10:36):
People think if the patient feels okay at a certain
jaw opening, that must be the right VIDO.
Speaker 2 (10:41):
Yes, and the book states unequivocally comfort is not a
determinant of correct video. You can make patients comfortable at
almost any vertical dimension, whether you open it or close
it quite a bit.
Speaker 1 (10:53):
So if comfort isn't the guide, what does determine the
physiologically correct video.
Speaker 2 (10:57):
It's determined by the biology of the muscles, specifically the
repetitive contracted length of the elevator muscles. The muscles that
close the jaw have a sort of programmed resting length,
and that dictates the video.
Speaker 1 (11:08):
Wow, okay, that's a major point. So what's the clinical implication.
If we're doing big restorative cases Crowns bridges, the.
Speaker 2 (11:15):
Implication is huge. You should generally aim to treat the
patient as close to their original existing video as possible,
because the muscles are already adapted to that length.
Speaker 1 (11:23):
And changing it significantly requires.
Speaker 2 (11:26):
It requires significant edipation time, especially increasing the video. If
you increase it beyond the muscle's natural contracted length, you're
asking those muscles to adapt to a permanently stretched position,
which can lead to fatigue. Discomfort, maybe even instability down
the road stick close to the original VBO whenever feasible.
Speaker 1 (11:46):
Got it. So, after we've established a stable CR foundation,
the next pillar seems to be anterior guidance.
Speaker 2 (11:52):
Correct. Once CR is stable the way the front teeth
guide the jaw during movement, the anterior guidance becomes the
dominant actor determine how the back teeth should be shaped
in function second only to CR itself, and it needs.
Speaker 1 (12:06):
To be in harmony with something called the envelope of function.
Speaker 2 (12:08):
Yes, the envelope function just refers to the natural programmed
pathway as the lower jaw follows during chewing, speaking swallowing,
the interior guidance needs to allow those movements smoothly without interference.
Speaker 1 (12:20):
The book uses a really elegant phrase to summarize the
goal dots in back, lines in front. Can you unpack
that for us?
Speaker 2 (12:27):
It's brilliant, isn't it.
Speaker 1 (12:28):
Dots in back means when the jaw is fully seated
in centric relation, all the posterior teeth should contact simultaneously
and evenly, creating stable pinpoint stops.
Speaker 2 (12:40):
Just dots, stable holding contacts in CR okay and lines
in front.
Speaker 1 (12:45):
Lines in front refers to eccentric movements when the jaw
moves forward protrusive or sideways lateral. As soon as the
jaw starts to move out of cr the anterior teeth,
incisors and canines should immediately contact and smoothly guide the
movement cause, using all the posterior teeth to separate instantly disclusion.
Speaker 2 (13:03):
Immediate posterior disclusion. Why is that separation so critical.
Speaker 1 (13:07):
Because it shuts down that muscle hyperactivity we talked about earlier.
Remember Williamson's EMG studies. If back teeth rub against each
other during side to side or forward movements, those powerful
elevator muscles firelight crazy.
Speaker 2 (13:19):
Okay.
Speaker 1 (13:19):
The anterior guidance acts like a circuit brigger. It protects
the posterior teeth from damaging lateral forces and keeps the
muscles quiet during eccentric movements. It's essential for comfort and
preventing wear or mobility. Makes perfect sense. And what about
the actual shape the form of the posterior teeth themselves.
What's needed for stability there?
Speaker 2 (13:38):
The main thing is directing forces down the long axis
of the tooth. Generally this means having the buckle cusps
the ones towards the cheek of the lower teeth fitting
neatly into the central fosa. The grooves of the upper
teeth stamp cusp into fosa.
Speaker 1 (13:54):
Okay, and the book specifically rejects a concept called bilaterally
balanced a clue for natural teeth. Why is that? I
know some schools used to teach that.
Speaker 2 (14:03):
Yeah, it was a concept bard from denture construction. Bilateral
balance means having posterior teeth on both sides contacting during
lateral movements. The book argues this as harmful for natural teeth.
Way harmful because those working in non working side interferences
during lateral movement generates significant lateral stress, especially against the
orbiting condyle, which isn't braced. This leads to things like
(14:24):
tooth mobility, excessive wear, and even periodontal breakdown. It creates
the exact muscle hyperactivity and damaging forces that proper anterior
guidance aims to eliminate. It's just not physiologically sound for
natural dentition.
Speaker 1 (14:38):
Okay, that's a clear rejection. So putting this all together
for complex cases, the book outlines program treatment planning, or PTP.
How does that help avoid guesswork?
Speaker 2 (14:48):
PTP is basically a systematic approach. It forces you to
check if those five requirements for stability, stable joints, muscle comfort, CR, MIP, coincidence,
anterior guidance, poster your ustability are met before you start
irreversible treatment.
Speaker 1 (15:03):
So you diagnose based on those.
Speaker 2 (15:05):
Five requirements exactly. You find the deficits, and based on
what's missing, your treatment options fall into logical categories. Reshape
the existing teeth, maybe reposition them orthodonically, restore them with
crowns or fillings, or sometimes surgery is needed for the
jaws or joints. It's a structured thought process, ensuring the
foundation is solid before you build the house, so to speak.
Speaker 1 (15:25):
I like that analogy, and the simplest form of reshaping
is often a clusal equilibration adjusting the bite. The text
gives that famous Mudl rule for eliminating interferences that prevent
CR closure.
Speaker 2 (15:36):
Yes, and when done correctly, equilibration based on CR is
incredibly predictable. The Medl rule is a lifesaver for figuring
out which incline to adjust on a tooth that's interfering
as a jaw closes into CR.
Speaker 1 (15:50):
Remind us what MEDL stands for me.
Speaker 2 (15:52):
Seal inclines of upper teeth or the distal inclines of
lower teeth. These are the specific inclines that, if they
hit prematurely, tend to deflect the mandible forward out of
cr So you adjust those specific inclines. Genius little rule.
Speaker 1 (16:07):
That is handy. Now, another really interesting point the book
makes is about severe wear. It argues that attritional wear
the kind from grinding or clenching rxism. It argues that
even severe wear from bruxism does not cause a loss
of video.
Speaker 2 (16:19):
That seems counterintuitive it does, but the explanation makes sense.
Attritional wear only happens if teeth are actually rubbing against
each other, meaning they are in the way during jaw movements.
But crucially, as the tooth structure wears down, the teeth
continuously erupts slightly to maintain contact and preserve that vertical
dimensions set by the muscles.
Speaker 1 (16:38):
So the teeth erupt to compensate for the wear, keeping
the vdo constant.
Speaker 2 (16:42):
Essentially, Yes, now, this is very different from erosion. Erosion
is chemical wear, maybe from acid reflux or ascetic drinks.
You know, that causes a different pattern, often dished out
lesions and can lead to VDO loss because it's dissolving
tooth structure independent of the occlusal function and eruption mechanism,
where versus erosion very different causes and effects on video.
Speaker 1 (17:04):
That distinction is critical. Okay, last major point we have
to touch on the critique of neuromuscular dentistry NMD. It's
a controversial topic. What's the book's main issue with the
NMD approach?
Speaker 2 (17:14):
The core criticism revolves around how NMD determines the treatment position.
NMD typically uses low frequency to ns like a mile monitor,
to relax the muscles and then find a byte position
based on where those relaxed muscles want the jaw to be.
Speaker 1 (17:29):
Okay, what's the problem with that?
Speaker 2 (17:30):
The problem is that this position derived electronically often results
in the condos being positioned significantly forward and downward compared
to centric relation, and achieving this often requires artificially increasing the.
Speaker 1 (17:41):
Video and functionally. Why is that forward downward position considered
unstable according to this philosophy because.
Speaker 2 (17:49):
To close into that forward NMD position, the muscles that
pull the jaw forward, the inferior lateral tarygoids have to
remain active, constantly fighting against the powerful elevator muscles that
are trying to the condoles back and up into cr AH.
Speaker 1 (18:03):
So it creates muscle conflict exactly.
Speaker 2 (18:05):
It sets up this chronic muscle in coordination. This isometric
battle between muscle groups. That's the very thing that a
functionally sound occlusion based on CR aims to eliminate. A
key requirement for CR is the timely release of those
forward pulling muscles as the jaw seats allowing the elevators
to close fully and rest. The NMD position often prevents
(18:28):
that release.
Speaker 1 (18:29):
That's a fundamental disagreement in philosophy and physiology right there.
Speaker 2 (18:32):
It really is.
Speaker 1 (18:33):
Wow. Okay, this has been an incredibly thorough journey through
the core principles of functional occlusion. If you had to
boil it down, what's the single biggest takeaway for someone listening.
Speaker 2 (18:42):
I think it's understanding the inner deependency, the TMJ, the muscles,
the teeth, they're all linked by following this kind of
sequential system based approach, stable joins first, then relaxed muscles,
then a harmonious bite built on that foundation, you take
the guess work out of it. Predictability, predictability, comfort, and
(19:03):
long term stability. That's the goal. Even if the final
result isn't a perfect textbook classiecclusion, if it's stable and
comfortable for that patient based on their physiology, that's success.
Stability Trump's idealized aesthetics every time.
Speaker 1 (19:17):
Stability is the goal. Love it, and maybe one final
thought to leave everyone chewing on, so to speak. Think
about the power of that load test. It really is
the gatekeeper verifying joint stability under load before you make
any permanent changes to the bite. That's the step that
underpins everything else.
Speaker 2 (19:33):
Couldn't agree more, and it helps solidify some of these
key diagnostic ideas. Maybe we can offer a little review exercise.
Speaker 1 (19:39):
Great idea, Okay, here it is for you to think
about review exercise. Imagine you have a patient presenting with
jaw muscle pain. You suspect it might be related to
a deflective interference on a back tooth design. The two
key clinical tests you had performed to confirm this diagnosis
and differentiate it from an intracapsular disorder a problem inside
the joint, make sure you state the expected outcome for
(20:01):
each test. If the problem is purely an inclusive muscle
disorder OMD,
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