1. Discuss Key points in the placement of a Class II composite resin restoration.

2. A class IV composite has been placed under Rubber dam and the shade is excellent immediately post op. Unfortunately, the patient returns the next day as the shade is now too light. Discuss POSSIBLE MISTAKES MADE BY THE CLINICIAN.

3. A Class IV resin composite that is out of the occlusion in all excursions of the mandible

keeps debonding. What could be the possible causes for this problem?

4. One step self etching adhesive is considered as semi permeable membrane. Discuss.

2. Use total etch technique and bonding agent. Etch at the enamel followed with dentin then agitate it for 15 seconds, rinse, mild blow until frosty white appearance can be seen. Apply a thin layer of bonding agent for 10 seconds, mild blow to spread the bonding agent to form a thin layer then cured for 20 seconds.

3. Build the marginal ridge first then cure.

4. Cure again from the buccal or lingual side after removing the matrix band to make sure all surfaces are cured.

5. Place the composite incrementally by cusp.

6. Remove the gross excess using white stone bur, finishing and polishing using soft flex disc

Q2.

1. maybe the clinician use self etch, for class 4 restoration, it is better to use total etch as it will create strong hybrid layer and increase strength
2. moisture contamination
3. no bevel, decrease strength

Q3
1. The shade is choose after isolating the tooth.
2. The shade is choose using uncured composite.
3. choosing shade under dental light/ extreme light exposure.
4. Choose the shade after the tooth has been dried. 

Q4.

-Self etch is considered as semipermeable membrane because It it is highly acidic and hydrophilic in nature. So, it will attract water from the dentin. The water will disturb the curing of bonding agent, resulting in low bonding strength.
- Self etch does not remove all the smear layer, means not all dentinal tubules are exposed. Because of that, self etch also have  less postoperative sensitivity.

2. A class IV composite has been placed under Rubber dam and the shade is excellent immediately post op. Unfortunately, the patient returns the next day as the shade is now too light. Discuss POSSIBLE MISTAKES MADE BY THE CLINICIAN.

- Shade of the tooth is chosen after the rubber dam isolation is done
- Shade is chosen using uncured resin composite.
-Shade is determined under dental light which makes the colour is slightly different with the original tooth colour
- Shade is chosen after the tooth is dried and dehydratred. 

3. A Class IV resin composite that is out of the occlusion in all excursions of the mandible

keeps debonding. What could be the possible causes for this problem?

4. One step self etching adhesive is considered as semi permeable membrane. Discuss.

Q2. A class IV composite has been placed under Rubber dam and the shade is excellent immediately post op. Unfortunately, the patient returns the next day as the shade is now too light. Discuss POSSIBLE MISTAKES MADE BY THE CLINICIAN.

- Shade is determined after the isolation is done
- Shade is determined using uncured resin composite
- Shade is determined under the dental light/exposed
- Shade is chosen after the teeth dried/dehydrate
- Show the shade of composite to the patient
- Compare the shade of composite to the adjacent tooth


Q3.  A Class IV resin composite that is out of the occlusion in all excursions of the mandible

keeps debonding. What could be the possible causes for this problem?

- Water contamination
- Not enough microporosities in enamel due to application of weak acid during etching
- No etching on the dentin
- Polymerization shrinkage (should use flowable composite)
- Self etch (should use total etch)



Q4. One step self etching adhesive is considered as semi permeable membrane. Discuss.

- 6^th – 8^th generation

- Some part of dentinal tubules are blocked by smear layer, and some part of dentinal tubules are exposed (Post-operative sensitivity < TOTAL etch)

- Formation of resin-impregnated smear plug in dentinal tubules (Bonding < TOTAL etch)

- Self-etch more acidic than total-etch → Self-etch more hydrophilic than total-etch
- One step self-etch is more water absorption than 2 steps self-etch

2. Use total etch technique and bonding agent. Etch at the enamel followed with dentin then agitate it for 15 seconds, rinse, mild blow until frosty white appearance can be seen. Apply a thin layer of bonding agent for 10 seconds, mild blow to spread the bonding agent to form a thin layer then cured for 20 seconds.

3. Build the marginal ridge first then cure.

4. Cure again from the buccal or lingual side after removing the matrix band to make sure all surfaces are cured.

5. Place the composite incrementally by cusp.

6. Remove the gross excess using white stone bur, finishing and polishing using soft flex disc, and vaseline.

Q2
1. shade is  determined after tooth have been dried
2. shade is determine under the dental unit lamp

Q3
1. polymerization shrinkage
2. wrong technique of adhesive system, eg: the clinician used self-etch adhesive system.
3. less retention form(not beveled the enamel)
4. Malocclusion. eg: uneven occlusal force and bruxism
5. the clinician does not follow the manufacturer's instruction

Q4
1.  6th - 8th generation.
2. Not all smear layers are removed, some dentinal tubules are still impregnated by the smear layer. Bond strength lower
3. Formation of resin-impregnated smear plug in dentinal tubules, leading to less post-op sensitivity in comparison to total etch.
4. Bond strength is lesser in self-etch than total etch.
5. Self etch is more acidic and more hydrophilic (due to HEMA), hema attracts water from pulp. then combine with composite.

2. Use total etch technique and bonding agent. Etch at the enamel followed with dentin then agitate it for 15 seconds, rinse, mild blow until frosty white appearance can be seen. Apply a thin layer of bonding agent for 10 seconds, mild blow to spread the bonding agent to form a thin layer then cured for 20 seconds.

3. Build the marginal ridge first then cure.

4. Cure again from the buccal or lingual side after removing the matrix band to make sure all surfaces are cured.

5. Place the composite incrementally by cusp.

6. Remove the gross excess using white stone bur, finishing and polishing using soft flex disc

Q2
1. Shade is determined after the isolation is done
2. Shade is determined using uncured resin composite
3. Shade is determined under the dental light/exposed
4. Shade is chosen after the teeth dried/ dehydrat

Q3
- Using self-etch instead of total etch. This is because there are some part of the smear layer and smear plug are removed so not all dentinal tubules are exposed. This might affect the formation of hybrid layer. If 4th generation of acid etching is used, it promotes the hybrid layer formation but the bond strength of the adhesive system is low which might cause the debonding of the composite. Thus, 5th generation is better in term of bond strength compared to the 4th generation.    
- High forces applied on the composite due to the high-bite causing the composite resin to debonding.
- Improper cavity preparation which there is no beveled applied on the cavity preparation. Thus, less surface area that are able to hold the composite.  
- Premature polymerization due to the exposing the to the direct light. 
- There is no moisture control thus affecting the composite resin as it is consist of the hydrophobic monomer. This may attract more water causes it to become swell and affecting the strength.
- Malocclusion such as class II, and III may also cause the debonding  of composite resin due to the forces applied during excursions

Q4
One step self etch is semi-permeable membrane because it doesn’t remove the smear layer completely. Therefore, the uncured monomer doesn’t fully penetrate the dentinal tubule. therefore, self etch reduce the post-op sensitivity. But it will reduce the bond strength between dentin and resin. This is because, when the bonding procedure simplify into one step, the adhesive solution became more hydrophilic because the increasing of acidic monomer concentration has reduce the resin-dentin bond. A more water-permeable hybrid layer also compromises the dentinal sealing, which results in the premature degradation of resin-dentin bonds and consequently of the restoration. The self-etch also contain hema that makes it more hydrophilic and cause less bond strength.