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Complex Amalgam Restorations

Doctor: Ghada Maghaireh.ALL SLIDES ARE INCLUDED IN THE SCRIPTReferences: 1- Complex Amalgam Restorations CH #19 (The Art And Science Of Operativ Dentistry). 2- Amalgam Restorations CH#11 (Fundamentals Of Operative Dentistry).Done By: Nihad Bishara Gewanna J. Ghazal

Today we will talk about capping cusps with amalgam restoration , we will talk about what to restore above broken tooth" crown" , of course we will consider here that already we evaluated the pulpal status of the tooth, is it vital ?! and we check if we removed all caries , now we have to restore the tooth with amalgam , also we will talk about:Pin-retained amalgam restorations - to learn how to use pin in the teeth in order to give more resistance and retention for retain amalgam , Non-pin mechanical resistance and retention features and this kind are not used widely today instead of that we use Pin retained amalgam restorations, part of the pin will be inside the dentin and part of it outside in order to retain the amalgam restoration .Now go back to non pin mechanical resistance and retention features " which we called them "secondary / auxiliary- retention features" also this type aid in retaining the amalgam in its place , because as you know amalgam need mechanical retention so as a conclusion we need mechanical feature that retain the amalgam restoration into the tooth , finally we will talk about Amalgam foundation when we have root canal treated tooth and we want to do amalgam foundation for that tooth .

As a s Summary, we will talk about : ( outline)

1.capping cusps with amalgam restoration2.Pin-retained amalgam restorations.

3.Non-pin mechanical resistance and retention features4.Amalgam foundation

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Indications:

1. Control restorations in teeth that have a questionable pulpal and / or periodontal prognosis . when we talk about this we talk in contrast with a crown for example a bad broken tooth most of the time needs a crown because most of the tooth structure is missing and we want to restore the clinical shape ,function and esthetics. Sometimes , this is the idea ( we want to restore the defective part of the tooth in order to make the tooth functionally work and to look esthetically ) now here instead of making a crown we want to make an amalgam restoration because in some cases we are not sure about pulpal and periodontal status of the tooth so we don’t want to make very costly restoration like a " crown " which need multiple visits ( we need to take an impression and then take it to the lab , we have to retained it back to cement the crown ) .

2. Control restorations in teeth with acute and severe caries."control the disease phase " so the amalgam restoration can be one of the control phases of our treatment plan ( control the patient oral hygiene and all the other factors ).

3. Definitive final restorations or foundations. Sometimes the amalgam itself can be the definitive restoration which means that I can use the amalgam and tell the patient that no need for a crown or for some reasons if the patent in a hurry and he doesn't want to do a crown, In some cases it could be a financial reason that the patient cant pay for a crown so instead of that we do complex amalgam restoration.

Factors to be considered:

1. Resistance and retention forms . It depends on the remaining tooth structure , if I have enough tooth structure I can put amalgam ,but in different cases when I don’t have enough structure and the tooth is badly broken that I don’t have any sort of retention the amalgam restoration will not be my choice .

2. Status and prognosis of the tooth .( this is what we talked about it in the previous page which is about pulpal and periodontal status ) according to this factors I will decide if Im going to put amalgam or something else in the tooth .

Indications:

1. Control restorations in teeth that have a questionable pulpal and / or periodontal prognosis.

2. Control restorations in teeth with acute and sever

3. Definitive final restorations or foundations

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3. Role of the tooth in the overall treatment plan: if a tooth is part of RPD I might need to put a rest or guide plane on it , so I have to consider that in my treatment plan I will make amalgam or crown , in order to afford these features .

Another example , the tooth may be a part of fixed partial denture (bridge) ,so I will not think about amalgam, I will make a crown , so I have to consider the oral cavity as whole in my treatment plan not only that tooth .

4. occlusion ,esthetics and economics'.

Occlusion: If I have high occlusion I need something stronger than amalgam, because it will be weakened by losing tooth structures.

Esthetics: amalgam is not an esthetic restoration, so I might consider something else like a) composite b) Porcelain crown c) Ceramic crown .To be more aesthetic in the aesthetic zone.

Economic: according to this factor I will choose the restorative material if it is amalgam! , composite! , crown! , or indirect restoration.

5. Age and health of the patient. if the patient is old , he doesn’t want to spend alot of time in treating his teeth, because he has medical problems , so we might think about amalgam restoration as a permanent restoration for badly broken tooth.

Contraindications:

Factor to be considered: 1. Resistance and retention forms.2. Status and prognosis of the tooth.3. Role of the tooth in the overall treatment plane.4. occlusion ,esthetics and economics'.5. Age and health of the patient.

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1.If the patient has significant occlusal problems : if the patient has bruxism or parafunctional habits we can put amalgam , but its not our final choice ,because it will not withstand the occlusal problems for long time, it might fracture.This might be a relative contraindication depending on the whole situation of the patient.

2. If the area to be restored is esthetically important for the patient. ofcourse we cant put amalgam, because amalgam is not an esthetic restoration, then it is contraindicated in this case.

Advantages:

1. Conserve tooth structure. If we compare the amalgam preparation with a crown preparation we will find that amalgam preparation will be more conservative, because in crown preparation we have to prepare the whole surfaces of the tooth, we have to remove 1.5 mm from the whole tooth structure to prepare it as an indirect restoration.

According to amalgam preparation, we don’t have to remove alot from the tooth structure; we just remove the defective structures and put some retention features in order to retain the amalgam in its place.

2. Appointment time. In any indirect restoration we need more appointments . if we are going to do a crown we might need two appointments.

3.resistance and retention forms: this is related to the tooth structure , we can gain more resistance and retention for the the restoration by a good and conservative preparation.

Note: the amalgam restoration it can be reversible to another treatment, because any time we decide to do a crown, we can prepare the tooth for it. But we can't prepare a crown treated tooth to do amalgam restoration.Economic. Its inexpensive when comparing it with any indirect restoration.

Disadvantages :

Contraindications:

1.if the patient has significant occlusal problems.2. if the area to be restored is esthetically important for the patient. of course we cant put amalgam.

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1.Dentinal microfractures: We will talk about them with the pin-retained.

2. Microlekage. might be some microlekage around the pin.

3. Decreased strength of amalgam .because there will be a lot of loss from the tooth structure, so the ability of tooth fracture will increase, the incidence of amalgam fracture will increase. And the proportion of tooth structure to amalgam will be less (the amalgam will be more than tooth structure) .so the resistance of the tooth to amalgam fracture will increase.

4.resistance form. Which is the resistance of the tooth to amalgam fracture

5. Penetration and perforation. when we use "Pin-retained amalgam restorations " there will be more chance to penetrating the pulp ( perforation to the pulp), or even to the periodontal ligament, for that nowadays the using of pin is very diminished , in order to reduce the problem associated with pins placement .

6. Tooth anatomy. Tooth anatomy and pulp chamber are very important when want to insert a pin. We have to consider some factors like :a) The high of pulpb) Remaining dentine because as we said before part of the pin will be inside the dentin

Capping Cusps With Amalgam :

Advantages:1. Conserve tooth structure.2. Appointment time3. Resistance and retention forms.4. Economic

Disadvantages:1.dentinal microfractures2. Microlekage3. Decreased strength of amalgam4. Resistance form5. Penetration and perforation.6. Trooth anatomy

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1) The facial or lingual extension exceeds two thirds the distance from a primary grove toward the cusp tip.2) Adequate resistance form.3) Survival rate of 72% after 15 years. 4)Depth cuts .5)2mm for the functional cusps.6)1.5mm for the nonfunctional cusps.

The guidance for the depth and the diameter is the diameter and the length of the bur, so if you have a 1mm diameter bur, you have to go 1mm( the whole diameter and the half of it) for the nonfunctional cusp, and if we are working on the functional cusp we go double of the bur diameter.

we put these depth cuts like a guidance we put them at first and then we connect between them , then we will do the amalgam restoration.

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We can also do capping for 4 cusps, a full occlusal cover but it will be difficult because we have to make multiple depth cuts.

Depth cutsreduce the cuspAmalgam capping.

Auxiliary retention and resistance forms: Sometimes we can put auxiliary retention and resistance form, like the retention grooves that we can do in class II cavity preparation whenever we don’t have enough resistance or retention.

This is retention groove that we can put in dentine to give us auxiliary retention feature. for example if the lingual wall of class II is too flared buccaly there will be Alot of tooth structure that its not parallel to the buccul wall- so we don’t get enough retention . In class II preparation buccal and lingual wall should be parallel or convergent occlusally to get more retention, sometimes we don’t because the presence of caries so we use auxiliary retention features to aid in retention for the amalgam.

Pin-Retained Amalgam Restorations :

Types of pins:1-self-threading pins: * Most frequently used- * The diameter of the prepared pin hole is smaller than the diameter of the pin. * 3 to 6 times more retentive than the cemented pins. * like : TMS- Thread Mate SystemSerrated like a screw ( برغي) we made a hole using a drill inside the dentin then we insert it with a screw driver, that’s why the hole is smaller than the diameter of the pin to be able to screw it (self threading it ) well inside the dentin, but there is a problem in screwing It because this will create a stresses inside the dentin making it more prone to fracture and microleakage around the pin later on.

2-Friction-locked pins.

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3-Cemented pins: it is like when you use cement, the hole that we made is larger than the size of the pin, and we use cement in order to cement the tooth inside the hole, this retention features is less than self threading and friction-locked pins.

Factors Affecting The Retention Of The Pin In Dentin and Amalgam: 1- Type : Self-threading > Friction-locked>Cemented.2- Surface Chrematistics (dimensions) Smooth or serrated Serrated pins are more resistant and retentive than Smooth pins/un-serratedself threading is the most retentive.3- Orientation(vertical or horizontal), number, Diameter.4-Extension into dentin and amalgam.

This is a pin like screw ,self-threading pin, serrated we made a hole inside the dentin then we insert the pin, so part of the pin will be inside the dentin and the other part will be outside so we condense the amalgam around the exposed part of the pin in order to retain the amalgam.

5-Number of pins it depends on:** the amount of missing tooth structure**the amount of dentin available: because we want to put them in dentin**the amount of retention required : more retention so more number of pins**the size of the pin : come in different sizes and diameter , length is optimum 2 mm, sometimes we cant put 2mm inside the dentine or we don’t have enough space for amalgam, so we cut the pin or bend it.**GENERAL RULE : one pin per missing axial line angle.

6- Location :** Its very important to know the normal pulp anatomy and external tooth contour to avoid penetration into the pulp or periodontium.** A current radiograph- to show the position of the pulp, to see the height of the pulp** A periodontal probe- to see the socket orientation of the external tooth surface** The patient’s age- to see pulpal extension.-PINS LOCATION IT SHOULD ALWAYS BE IN DENTIN.

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7-Pin Hole Position:Here we have two missing line angles so we place two pin holes, it should always be in dentin, we never put pins in enamel because enamel is fragile and it will fracture because of this it should be minimum 1.5mm away from the external surface of the tooth or 1mm inside the dentin.

8-Pin placement: 1-Pilot hole with small round bur- to make small hole inside the dentin2-A twist drill at very slow speed3- Insertion of pin: conventional latch-type slow speed handpiece and TMS hand wrenches.-Thread mate system(TMS) has a kit – pins with different diameter and a drill.-We use small round bur to make a small pilot hole inside the dentin exactly where we are going to insert the pin before using the drill because the drill tend to move away (slide/ . (تتزحلق- Pin can be inserted by wrench type manually or with rotary instrumenmts.

This could be a problem because we have to be careful, we have to know exactly the surface orientation : external tooth surface to avoid penetration into the periodontal ligament and to avoid the pulp.Always know the inclination of the external tooth surface to know the direction of the drill to make the pilot hole in the right place to avoid penetration, or perforations.

Bending And Shortening Pins:

Pin position

Pilot hole.

Twist drill/Slow speed

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Sometimes the exposed part of the pin is too long that we don’t have space to condense the amalgam , we should have minimum (THE DR SAID 1.) space to condense the amalgam , so we can cut it so we use:- A diamond sharp high speed carbide bur.- Some systems have bending tool it should be used if pending of the pin is necessary- bend the pin to have more space to condense the amalgam.

Possible problems with pins:** Failure of pin retained restoration- the whole restoration come out with the pin.** Broken drills and broken pins during insertion or placement**Loose pins(not retentive)- the hole become larger while we inserting the pin.**Imp**Penetration into the pulp and perforation of the external tooth surface.

Non-Pin Retained Amalgam Restoration:Other form of retention features, which means we can make auxiliary retention features in amalgam itself and that’s what is usually done , make retention features in dentin itself.1-Circumferential slot: with small inverted cone bur.

2-Amalgampins: **1.5-2mm depth **0.8-1.0mm diameter **Entrance to amalgampin channels should be beveled.different from the pins that we talked about, amalgampins are not screws.We made them with round bur or pear-shaped bur that we make a hole inside the dentine then I condense the amalgam inside it (we don’t insert pins) with small instruments like small condenser, burnisher , or small applicator.It’s the most likely used if I want auxiliary retention, or if I want to do post.

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3-Peripheral shelves:**2mm axial depth and 1.0mm cervical depth. Less retention than circumferential or amalgampins.

Pin-Retained Vs Non-Pin Retained Amalgam Restorations.

As we said before Non-pin slot, retention groove, amalgampin, peripheral shelvesPin we use pins

1- pin retention is more frequently used in preparations with few or no vertical walls.2- Non-pin are indicated in short clinical crowns and in cusps that have been reduced 2-3 mm for amalgam(when we use amalgam capping)3- More tooth structure is removed preparing mechanical retention and resistance forms( we said pin retained may cause fracture but we don’t remove tooth structure, Non pin retained we remove dentin so we are weakening the tooth)4-Mechanical retention and resistance forms are less likely to create microfractures in the dentin and to perforate the tooth or penetrate into pulp ( Pin retained- may cause microfractures and gaps in dentin because we screw the pin inside the dentins so its more harmful than non-pin retained)

Amalgam foundations:Foundations: we make it before we do indirect restoration.- Amalgam is preferred because it is easy to use and stronger.any posterior teeth that had RCT should be occlusaly covered, after obturation of the canal we have to put a crown usually , we need to do foundation of the canal we can put amalgam (permanent restoration) before any crown preparation, we can also use composite or GIC under a crown as a foundation but the strongest material is amalgam.-Tooth preparation for amalgam foundation:** Pin retention**Slot retention**Chamber retention(more advanced, we will talk about it in next lectures)- when we have endodonticaly treated tooth either anterior or posterior sometimes we need a post inside the canal or crown in order to restore the tooth when we don’t have a lot of tooth structure , sometimes amalgam can be a foundation for us or kind of retention if we have enough chamber like the picture.

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