口腔种植学是口腔教育中较新的学科。虽然现在我们都有共识，种植⽛相关的理论知识，⽆论是治疗⽅案的规划，还是后期的随访和维护，对于每⼀个职业⽛医都⾮常重要。然⽽，在当下全球的口腔医学本科培养体系中，它的覆盖程度还远远落后于其重要性。 在此背景下，香港大学口腔医学院联合⾹港⼤学的线上教育专业团队，历时⼀年有余，设计并制作了这门为期五周的⽹络公开课，旨在传播以循证医学为基础的，客观、全⾯的⽛种植学相关知识。这门课程⾯向全球，双语教学，完全免费。学员将在20 多位全球领先的种植学专家的带领下，完成五个模块，系统地学习⽛种植学。
天然牙和种植牙－生物学相似性和不同点
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From the course by The University of Hong Kong
口腔种植学 （Implant Dentistry）
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From the lesson
种植牙，生物学基础，技术工艺
什么是种植学？这一学科如何开始，又是经历了什么重大突破发展到现在的阶段？什么样的种植体更有益于我们的患者？本模块中，我们将回顾骨结合背后的基本生物学概念，以及其对临床决策的影响。
Meet the Instructors
Nikos MattheosClinical Associate Professor in Implant Dentistry
The University of Hong Kong
In this lecture, we will go through the difference
between the tooth and the implant
from a prosthodontic point of view
in order to explain why technical complications
are more frequent in implant supported reconstructions
compared to tooth supported.
Let's compare the tooth with the implant.
In teeth, within five years,
around 16% of the reconstruction have some complications.
On implant supported, it's about twice as much.
The most frequent complications on the tooth side
is caries and apical lesions.
And on the implant side, chipping is most frequent.
The main difference is that the tooth has a periodontium,
the implant is ankylotic.
One of the functions of the periodontium
is that it works as a shock absorber.
Everywhere around us we have shock absorbing constructions.
The periodontium protects the crown
from rapid and heavy forces.
The dentin also works as a shock absorber.
The clinical implication is never to do
ceramic reconstructions on both jaws.
Do a composite reconstruction in at least one jaw instead.
The composite has a shock absorbing function.
Compare when hitting two glasses seen to each other.
If they are ceramic, they will break easier
than hitting one ceramic and one plastic glass.
The next difference is that the periodontium
allows the teeth to elongate, intrude, rotate and tilt.
It allows movements.
This can be exemplified with the patients
that often say that they feel tension
or it feels tight when trying
a large framework on the teeth
but after around 10 minutes, the spanning has disappeared.
The framework has worked as an orthodontic device
and move the teeth to a more favourable position
depending on the small misfit of the framework.
After checking the framework,
taking it off also feels easier many times.
The implant is ankylotic and will not move.
Neither would it follow the growth of the jaws.
The clinical implication is that on teeth,
the reconstruction will always be strain-free,
while on implant there will always,
more or less, be a misfit.
The bridge will be slightly bent
giving unfavourable tension to the ceramics,
leading to chip offs or unfavourable loads on the screw.
If we take an even closer look to the periodontium,
we will find different receptors in the periodontium.
Two of these were studied by Trulsson et al.,
“the saturated and the unsaturated”.
In one of many studies, he examined how
two of the receptors signal
while holding and biting through a peanut.
In the bite phase, the saturated receptors
trigger at maximum, as soon as, the biting phase started.
But they got quickly saturated and stopped triggering,
while the non-saturated receptors follow the bite force.
He compared natural teeth
with complete denture and the implants.
In this slide we see the hold and biting force.
The patients with dentures and implants
lack the receptors.
Meaning that they will not feel where the peanut is
and have another interception than patients with teeth.
It will give a different pattern
in the holding and biting phase,
so it's not so much about the biting force
as it is about the precision.
The periodontal receptors signals
very detailed information about position,
direction and intensity of chew and bite forces.
This information is utilized by the brain
to regulate the jaws movements during normal operation.
Patients with implants which lack this information,
demonstrate clear disturbances
in the fine motor control of jaw regulations.
Also, implant doesn't feel interferences
in the same way as teeth.
The clinical implication for this is
that with teeth, the jaws will automatically try
to chew in a cusp fossa relation
giving a load through the root.
While with implants,
the patient can chew a little on the side without knowing it
giving bending forces to the reconstructions.
So in patients with implants,
the reconstruction should have more flat cusps
and more narrow occlusal table
in order to avoid the bending forces.
One of the anatomical difference
between the tooth and implant
is the fibres supporting the surrounding tissues.
In this slide, we can see the fibres that are the same
for the teeth and implants.
The small dots represent the circumferential fibres
surrounding the tooth like a rubber band.
But the tooth also have cement in certain fibers
or Sharpey's fibres originating from the cement
to the bone and the gingival tissues.
The clinical implication for this is
that the cement can penetrate much easier
and deeper when cementing a crown on an implant
compared to a tooth.
It is sometimes hard to see
that there is cement excess
and many times you can't see it on the X-ray at all.
This can give you fistulas and bone loss.
In summary, we do have the differences
between tooth and implants
is the shock absorbing effect,
the movements of the teeth.
We have the perception
and finally, we have the anatomical differences.
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