Lecture 12, Metals in Dentistry II (Script)

8/3/2019 Lecture 12, Metals in Dentistry II (Script)

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Metals in dentistry (2(

Dental Material II Lecture # 12

We have stopped at slide 26 last lecture, so we will continue

with different forms of metals that has been reshaped so that itcan have different application in dentistry.

Wires:We talked about wires which are used in orthodonticstreatment, it can be made from stainless steel, cobalt-chrome-nickel, titanium...etc.

These wires are able to resist deformation so when the dentistapplies them with the orthodontics appliance he needs to tendtheir shape, these wires have a tendency to go back to itsoriginal shape, this sort of force is used by the dentist to movethe teeth into different position, so when the dentist place onthe wire and change it's shape, the wire start trying to go backto it's original shape (straight shape) as it move it going toapply stress or force on the teeth and this force utilize by thedentist to move the teeth into certain position (such as if we

have spacing or crowding between teeth.(

So this specific quality of these wires is used to move the teethinside the oral cavity in the arch by the orthodontist ,becausewe know in the orthodontic we have malformed position ofteeth or the teeth aren't in their normal position; they maydented lingually or buccally, or may crowding or teethoverlapping each other and we want to straight it in the mouthto have a normal relationship, and this done by placing the

orthodontic devices, some of these devices contain thesewires and because these wires can produce stress by try to goback to their original position,

It can be used to move the teeth, if it place for example behindor in front of the teeth they can exert force which can move theteeth whether buccally or lingually, mesially or distally, so thisis an internal quality within the wire itself because it has been

deformed or it's shape has been changed.

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These wires are available in different diameter or gauge so thedentist can choose which gauge is suitable; the thicker thewire, the smaller the number of the gauge (reverse

proportional. (So if you have a wire with a number of gauge = 0.8 and anther

wire with a number of gauge = 1.8, which one is thicker?The first one with a number of gauge = 0.8, because thethicker the wire the smaller number of the gauge.

"You have to be careful about this sort of relationship."

Brackets and bands :They are also made of rod metal alloy, so the shape of metalhas been changed so they can be used in orthodontic

treatment, they can be made into bands or brackets or wiresall of these are made of rod metal alloys can also be made ofstainless steel, some of these can be cemented on the toothlike brackets and bands and composite are usually used toattached them to the tooth surface, if you have orthodonticprostheses inside your cavity you know what we are talkingabout.

Again, it is just anther example of metal alloy that have been

reshaped to be used in different ways in dentistry, so they canbe made from stainless steel, can be attached on the teeth byusing composite or cement, these bracket and band can holdthese wires in their place, the wire can be solder or can beinserted within the bracket itself in their certain place for it.

Lingual retainer:Again, it just anther example of different application of wires in

dentistry.After finishing orthodontic treatment these wires can also beused to retain the final position of teeth, to prevent returning totheir incorrect position, so again stainless steel wires withcertain gauge can be used.

]Note] : all these examples of different application of wiresare in orthodontic treatments ( lingual retainer ,brackets and

bands.(

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Implant materials:

Metal alloy can also be used to make implant, we all know theimplant ))everyone wants to do implants today

because they can earn a lot of money, so implants are used to

replace one tooth or multiple teeth, it can be used to returncrown on the top or bridge or even complete denture, so theimplant mainly consist of either titanium or titanium alloy whichis more popular because it is more stronger than pure titaniumused on its alone.

]Note] : usually we use titanium mixed with other metals(to make it stronger) to make the implants that insert in the

bone.so titanium alloy are mostly used because it is stronger than

pure titanium.

Titaiunm is biocompatible material, it is inert( )doesnt cause any irritation or damage, and remember we areplacing it inside the bone (inside the body) so it is needs to bebiocompatible.

Usually what the dentist does in implants appliance is:1.Removing a flab of gingiva.

2.Expose the bone.3.Drill a cavity or a hole inside the bone.

4.Fix the implant there.

Then after sometime a crown may be fixed on the upper partof the implant or a complete or partial denture, so your

restorations are stable.This is an example of the upper part of the implant whichappear in the oral cavity(the crown hasnt been placed yet.(

Inside the bone it looks like this:

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This sort of implant is called endosseous (inside the bone) and

this is the type of implants that used nowadays.

]Note] : the most popular type of the implant that is usednowadays is endosseous.

So the part of implants inside the bone is called fixture, thenthere is a part that expose in the oral cavity where you can

attach the crown,, so this is the

implant tooth.

It looks almost natural, so they saythis is better than actually preparingthese teeth on both side and makinga bridge because this is more

conservative, instead of preparing the central of this side andthe lateral of the other side to make a bridge, you only need todrill a hole in the bone and place the implant.

There are certain requirements to get implant teeth:1.The bone needs to have good width, good length ,good

quality.2.No inflammation, healthy gingiva etc.

So not everyone can get implant..!!We will talk about implant in more details later on; there islecture about implant.

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Subperiosteal:It is placed beneath the periosteum of the bone (fibrouscovering of bone), you dont need to know the procedure, youjust have to know this type of implants.

Transosteal (mandibular staple: (Trans-osteal means that the implant will be through the bonefrom bottom to top ,, it is not used commonly these days , theyused to use it if there is a lot of bone resorption, because theywant to use all the bone height, so it is not common now, the

most common type is endosseous implant.

In these cases (Subperiosteal, Transosteal, endosseous) it is

important for the implant to be union with bone, so when youplace the implant since the material is biocompatible the boneis going to form all around the implant and all the template, ifthere is movement or mobility this means implants failure.

Some of this implant have certain service treatment. Theyused calcium phosphate or something like hydroxyapatite theyplace it in the surface of the implant that is going to be inside

the bone , why do we do that?To encourage bone formation and deposition on the implantand lead to good contact between the bone and the implant.

So sometime we put a material like calcium phosphate (thesame material found in the bone) in the surface of the implantto improve the bone formation all around the implant(osseointegration) so it will fix the implant in the bone firmlyand that lead the implant to withstand the stress inside the oral

cavity.

Some people say after drilling the hole and placing the implantwe shouldnt load that area at all; the patient shouldnt use thatteeth or bite on it and shouldnt immediately place the crown,

you have to allow a few weeks for tissue to heal..

Other schools say NO; immediately loading is good because itstimulate the bone formation,,, so some people support thisschool and other support that school, but I think most peopleprefer to leave the area of implant without loading to allow

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tissue, gingiva and bone to heal and the success of thisprocedure higher than when immediate loading is placed.

There are certain ways to take care of implant and retainrestoration:

1.Certain toothbrushes.2.Certain type of flosses.etc.

The important to know here is a good oral hygiene is a most,otherwise the implant will fail; just imagine that the implanttooth is a normal tooth with root, if you dont care of the gingivaand periodontal tissue, inflammation will happen likeperiodontitis and the bone will be lose, there will be mobility

and just like a normal tooth it will be loose.

I always tell patients they come to the clinic and worry aboutthe caries and the gingiva is inflamed with a lot of calculus,that if you dont care of the things that support your tooth evenif it is healthy (it isnt carious) the tooth will become mobile and

you will lose it.

]Note]: we have to care about the gingival and periodontaltissue, as we take care of the teeth, because the severinflammation of the gingiva and periodontal tissue cause boneresorption and that lead to lose the tooth even if it isnt carious.

Taking care of gingiva and periodontal tissue is a mostspecially in this case (implant teeth); they can easily retainplaque and calculus that is why they need extra attention by

using:1.mouth washes (Antibacterial agents(

2.toothbrushes and toothpastes ( shouldnt be abrasive,otherwise it will damage the surface of the implant that

expose to the oral cavity.(3.certain type of flosses.

4.wooden sticks (toothpick); sometime it is necessary.

Hygiene visit:

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1.Routine examination:This is to the dentist to notice any side of bleeding,inflammation or soreness all these indicate that there issomething wrong and it needs quick treatment.

2.radiographs:are always taken in cases of implant to see that the bonehasnt desorbed ; it is still in its place.

3.examine soft tissue for edema, erythema, bleeding.4.scaling can also be done.

No ultrasonic scalers need to be used, plastic instruments areused so that we dont scratch the surface of the implant, andno stainless steel instruments are used against the implant,

this is all points that you need to be aware of when a patientcome to our clinic and he/she has an implant retainedprostheses either it is bridge or crown or complete denture.

]Note]: we prefer not to use any ultrasonic or metal handinstruments to clean the plaque and calculus around theimplant because it may scratch the surface of the implant andcause more accumulation of the plaque next time, so we prefer

using plastic or gold and Teflon coated instruments; so itdoesnt scratch or damage the surface of implant.

Implant failure:Causes:

1.if the technique during surgery is poor.2.contamination or infection.

3.poor quality of bone.4.excess heat during drilling the hole inside the bone.

5.All of these can lead to failure of the implant and this meansthat our treatment fail, and we need to more damage or

drilling in the bone.The signs and symptoms of implant failure are similar to theperiodontitis; you see that there is inflammation of thegingiva, bone lost and loosening of the implant.

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]Note] : we have to examine the implant frequently if thereis abvious movements for the implant that means the implantfails, because it has to be fix firmly in process calledancolosses "not sure" the implant attach immediately to the

bone without periodontal ligament or fibrous.(

Endodontic posts:Anther type of rods metal alloy are Endodontic posts, it looks

like this:

-Some of them can be metallic other are nonmetallic.-Some of them are straight other are tapered.

-Some of them have smooth surface other have ruggedsurface.

Now, what are they used for?

If you have tooth that has been root canal treated and thecrown is badly destroyed you can't place a filling or preparing itfor a crown , so you need to have a core either made ofamalgam or composite or hybrid GIC ,,, so how do we use the

posts in this case?

In the root canal where it is filled or obscured, part of the fillingin the canal is removed and then these posts are placed insideand fix by cement ,on the top of them (coronal) amalgam or

composite or may be hybrid GIC are placed to make a core ,on this core a crown may be placed.

These posts can be "ready made"; you buy them from themanufacturer, and along with them you have certain size ofburs used to drill inside the canal, so according to the size of

the bur you select the size of the post.

In other cases you need to make one according to the size ofthe canal of the patient "costume made" so when you removepart of the filling inside the root canal, you need to take an

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impression (the impression material pass through this canaland take impression to it and to the surrounding teeth also)then send it to the lab, and the lab will make us a post and thecore is already attached to it, so you just cement it to the

patient tooth, and on the top of that a crown may place.

]Note] : in the lab, they use lost wax technique to makethe post that fits to the patient canal (special post) with a coreattach to it, so the post and the core are made of wax at first

then it is melted and replaced by metal.

Again, prefabricated posts (ready made) have specific bur withcertain size according to the post size. So you drill inside theroot canal with a certain bur and then the matching size of

posts are cemented inside, on the upper part of the post(visible part in the oral cavity) amalgam for example is placedto make the core, and then the crown may be placed.

In costume made post you need to prepare your root canal,then remove part of filling inside the canal and take animpression, send it to the lab to make the post with a core

attaches to it, then you may place the crown..

]Note] : posts can be different in shape, diameter andlength and they are all cemented inside the patient root canal ,and the core made from filling material.

That's it.. ^^Forgive me for any mistakes

Done by : Sakha'a Ali Twaissi.

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Lecture 12, Metals in Dentistry II (Script)