cons sheet # 9 - Dania Salhab

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cons sheet # 9 - Dania Salhab

Post by Shadi Jarrar on 15/5/2011, 7:22 pm

بسم الله الرحمن الرحيم

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http://www.4shared.com/document/oiH2AHYn/Sheet_cons_9.html
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.Conservative Lecture: no.9
.Dr. Yara Oweis
.Done by: Dania Salhab
.Date of the lecture: 4/4/2011
** Some sentences are underlined because the doctor didn't mention them but I found them in the last year's sheet…
Posterior Composite Restoration
* Today our lecture is about posterior composite, its indications, cavity preparation and placement.
* Properties of composite which make it suitable for classes I and II cavity preparations are:
1. It has sufficient strength.
2. It is insulative and therefore doesn't require pulp protection with bases, because the bonding agent is considered as good as a liner.
3. It bonds to tooth enamel and dentine.
4. Tooth preparation is very conservative because we don't need to provide a boxlike form that we need in amalgam restorations (mechanical retention).
5. It is now possible to restore the missing tooth structure and support the remaining enamel without the need to remove much of it (undermined enamel).

* Indications:
1. Small to moderate restorations preferably with enamel margins. While if the enamel margins are missing, we use amalgam. This was considered with older generations, but now we can use composite with a large cavity without any problem except the polymerization shrinkage. (Larger the cavity is >> more the polymerization shrinkage; this can affect our tooth structure and the filling itself).
2. Most premolar or first molar teeth, especially when esthetic are of a concern, because as we go back, it is harder to isolate. While in the 2nd and the 3rd molar teeth, they are far away so esthetics is not important, also they are difficult to isolate.
3. A restoration that doesn't provide all the occlusal contacts, as we know the wear resistance of composite is lower than amalgam.
4. Where proper isolation is possible. For example if we have lingually tilted lower posterior tooth, we can not isolate it even with a rubber dam so we shift to another option.
5. Some restorations that may serve as foundations for crowns. As we know the foundations materials are three types:
. Amalgam >> the best
. Composite >> mainly used
. Glass ionomer >> the weakest
6. Some very large restorations that are used to strengthen weakened tooth structure for interim or economic reasons. Explanation...if we have a huge cavity, we can't use amalgam because there isn't enough retention even with retentive means, so we choose composite filling.

* Contraindications:
1. When the operative site can't be probably isolated. Although amalgam is less sensitive, this doesn’t mean we shouldn't do a proper isolation.
2. With heavy occlusal stresses.
…Actually this is not an absolute contraindication, but patient with this case he/she needs more follow up visits, because composite may wear off and this can affect the occlusion.
3. When the occlusal contacts are only in composites, in this case we prefer to use indirect restorations!
4. In restorations that are extended over the root surface. Because composite doesn't bond well to cementum there will be a gap, in this case we shift to amalgam if we have a good retention (box-like cavity) or to glass ionomer.

* Advantages:
1. Esthetic in comparison with amalgam and even with glass ionomer.
2. Conservative tooth preparation, because as we said before we don't need to extend the cavity preparation to provide mechanical retention like amalgam or even to remove the unsupported enamel, although sometime we need to provide the box-like form in huge cavities for resistance!
3. Easier and less complex tooth preparation, we just remove our caries and that's it, we don't need to provide walls or retentive grooves like amalgam.
4. Economical, compared with indirect restorations.
5. Bonding benefits; decreased microleakage, decreased recurrent carries, decreased post-operative sensitivity, increased retention and increased strength of the remaining tooth structure.

* Disadvantages:
1. Some disadvantages are material related, like:
- Greater localized wear in comparison to amalgam.
- Polymerization shrinkage effects.
- Linear coefficient of thermal expansion.
- The Biocompatibility of some components of the material either causing allergic reactions or their toxic effect on the pulp through the dentinal tubules.
2. Composite requires more time to be placed because there are more steps to be done >> acid etching, cleaning and washing, bonding agent and adding the composite in increments >> finishing.
3. Composite is more technique sensitive.
4. Composite is more expensive than amalgam.
* Types of Posterior Composite Restorations:
1. Pit and fissure sealants.
2. Conservative composite and preventive resin, these are mainly used in Pedodontics.
3. Class VI (caries on the cusp tips)
4. Class I
5. Class II
… Some information about class II, The access is either:
- Through the marginal ridge (conventional cavity, beveled conventional or modified).
- The marginal ridge is preserved
- MOD cavities which are the extensive cavities.

* The clinical technique for composite restoration:
1. Anesthesia.
2. Shade selection, that should be done before the preparation because once we put the rubber dam dehydration will occur, the color may change.
3. Checking the occlusion to know the points of occlusal contact and where to make a fosse, pit or a cup.
4. Tooth preparation (conventional, beveled conventional or modified).

* Shade Selection:
- Shade guides are provided for each manufacturer.
- Composites are provided in enamel and dentine shades in addition to translucent and opaque. We need to use a translucent composite instead of enamel composite in some patients that have translucent incisal edges or even translucent cusp tips.

* Checking the occlusal contact:
- We should check the occlusal contacts on our tooth and the adjacent one (reference).
- After we finish our restoration we should examine our occlusion by using an articulating paper to make sure that we have restored the occlusal contacts in the same distribution and intensity as before.

* Tooth Preparation:
- Tooth preparation depends on the extent of the caries lesion and on the size of our cavity.
- As we all know we have three types of tooth preparation:
1. Conventional.
2. Bevel conventional.
3. Modified.
- Various cutting instruments can be used in our preparation:
1. The size of the instrument that we use determines the size of our cavity. For example if we have a class III on anterior tooth, we need to use the smallest bur in order not to increase the size of the cavity.
2. The shape also depends on the resistance form which we want. For example if we want to make a modified cavity preparation, we can use a round bur. On the other hand, if we want to make a box-like cavity, we should use a fissure bur. (but dr.Yara said; it is better to use an inverted cone with rounded sides).
- If the occlsual surface is assumed to be extensive, the more box-like design is preferred. Explanation… if we have a big cavity, we need to do some sort of retention and resistance so we can't do a modified cavity, we do a conventional one. Resulting in a great resistance against fracture.

… Note: In composite restorations we prefer to use a diamond bur to get a cavity with a rough surface in order to increase the surface areas for the bonding agent.

- Bur preferred to be used as we said before is inverted cone with rounded sides, why? It provides a flat floor (resistance against fracture), results in occlusal marginal configuration that is more representative of the strongest enamel margins, enhances the retention form and more conservative faciolingual width preparation.
… The doctor showed us representative figures of a conventional cavity preparation, and here are her notes about them:
1. The extent of the cavity buccolingually is detected by the amount of the caries lesion.
2. If we have a small and shallow cavity we could make a modified cavity preparation, it is not a must to make a conventional one always.
… The doctor asked a question >> in which cases we make the beveled conventional preparation?
1. When we have a class I with buccal (mandibular teeth) or lingual (maxillary teeth) extensions.
2. In areas with less occlusal stresses, because beveled enamel is a thin layer, so we never do a bevel on the occlusal surfaces of the posterior teeth or on the lingual surfaces of the anterior teeth.
3. When the area has no contact.

… Note: We can't do a bevel on the gingival margins because we could cut the gingiva, so in class V we do a bevel on the incisal side only.

…Continue with tooth preparation:
- Extension into the marginal ridges, we should be away from them by about (1.6mm) and not to undermine the enamel of the cusps.
- The pulpal floor should always be flat except in some areas that may result in pulp exposure … we follow the DEJ.
- If the extension is required toward the cusp tip, then the same approximate (1.5mm) depth is maintained.
- Caries remaining on the floor should be removed by a low speed round bur, especially if we have a deep cavity in order not to make an injury to the pulp.
- No attempt is made to place bevels on the occlusal margins.
- The marginal form of a groove extension on the facial or lingual margins maybe beveled with a diamond bur, resulting in a (0.25-0.5mm) width of a bevel 45◦ angled from the prepared walls. (Imp. numbers for the next year).
… Only cavitated caries lesions are prepared in the manner described, meaning if we don't have cavitated lesion we do a modified cavity preparation.

* Modified Class I preparation:
- Used for minimally involved class I or faults.
- Usually doesn’t provide the characteristic resistant form features like boxlike design and flat walls.
- More rounded cutting instruments are usually used.
- This preparation is less specific in form.
- The initial depth is usually (1.5mm), (0.2mm inside the dentine) but the pulpal floor may not be uniformed.

* The Restorative technique:
As we said before in composite restoration we first do the shade selection >> check the occlusal contacts >> isolation (preferred to be with a rubber dam) >> tooth preparation, then:
1. Acid etching.
2. Enamel and dentine bonding and curing.
3. Composite insertion in increments.
4. Finishing and contouring.

* Class II Composite restoration:
1. Initial assessment (what type of cavity we want to do), assessment of the tooth itself and assessment of the occlusal contacts.
2. Tooth preparation, might be conventional, beveled conventional or modified.

* Proximal Composite Restoration:
We have three types of cavities...
1. Access through the marginal ridge, which is the conventional class II.
2. Marginal ridge is preserved.
3. MOD cavity.



* Cavity preparation:
1. Access to carious dentine by the removal of the enamel over the marginal ridge, this in a non-cavitated lesion. For example; if we have incipient carious lesion in which the marginal ridges are intact, and we saw it on the radiograph only not clinically, we first remove the enamel to get the access.
2. Cleaning the DEJ (always we clean from the outside to the inside), because if we accidentally exposed the pulp and end up with a clean cavity, we can do pulp capping. On the other hand, if we didn't clean it well then the bacteria will accumulate in the pulp.
3. Excavation of the caries over the pulp, incase we have a large deep cavity, we may use a low speed large round bur for the last layer of the caries to be removed, or we may use the excavator, it depends on how much we are close to the pulp.
4. Unsupported enamel is left in the cavity, (opposite to amalgam restoration).
5. Beveled or not?!
- For the occlusal part >> no bevel
- For the gingival margins >> no bevel
- On the axiopulpal line angle >> bevel
- Buccal and lingual extensions >> bevel



* Lining:
- Calcium hydroxide is used only in composite restorations when we need to do direct or indirect pulp capping.
- In a very large cavity, glass ionomer or resin modified glass ionomer is mainly used to minimize the stress of the polymerization shrinkage on the tooth structure.

* Placing the Matrix:
- We use the matrix to replace the missing wall, make a proper contour and to avoid overhanging of the material during packing.
- We have many types:
1. Tofflemire.
2. Ivory.
3. Sectional, this is especially to composite

* Etching:
- Is an application of the bonding agent.
- Usually for (10 sec), then washing and drying (gentle blow), to make it thin to ensure that composite won't undergo pooling at the line angles.
- Curing by the light.
- Placing the composite in increments, start with the deepest part, each increment should be with a maximum of (2mm-2.5mm) in order to cure it well, because this is the depth for penetration of the light.
* Finishing the restoration:
- Remove the matrix band.
- Restore the anatomy of the tooth structure using the composite finishing burs, we have different shapes.
- Check the contact points and the interdental area is finished with fine finishing strip when needed. Be careful not to open the contact area.

* Composite finishing burs:
The doctor showed us some figures containing the burs that we need, just like what we used in the laboratory session, like:
- Diamond high speed burs with different shapes.
- White stone.
- Mandrel.
- Disks.

* Cavity Preparation when the marginal margin is preserved:
- Lingual approach.
- Buccal approach, suitable for the teeth that are tilted lingually.

The end
Best of luck in the final exams

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Shadi Jarrar
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تاريخ التسجيل : 2009-08-28
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