Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            nd mixing. 
5. Inadequate covering of margin area.  
Errors: 
1- the restoration & tooth interface is weaker:  
 bubbles may be large enough to affect the luting agent,  the space to be filled, 
the luting material is thicker. 
2- the prosthetic material could be thinner,  the risk of failure. 
solved by:  
 achieving haemostasis, especially with hydrophilic impression materials. 
5) Poor margin detail (not visible finish- line) (Inadequate margin): 
Causes: 
1. Ginigival inflammation & bleeding.  
2. Subgingival finish-line. 
3. Localized gingival overgrowth. 
4. Retraction cord displaced from sulcus. 
5. Inadequate tissue displacement. 
6. Insufficient wash materials. 
7. Improper material injection into the sulcus. 
8. Tearing of the margin. 
9. Exceeding working time of the material. 
Errors with poor margin detail: 
1- overhanging restoration                              2- restoration with open margins. 
                                                              
    
 
How to avoid poor margin detail: 
1- Using retraction cords with syringeable haemostatics is the best way. 
2- One technique is to use a double retraction cord. 
3- retraction pastes placed into the gingival sulcus after preparation. 
4- A diode laser can help widen the sulcus & improve visualization of the prepared 
margin while achieving haemostasis.  
127
 
 
1
2 
3
4
 
5) Marginal tears: 
 
Causes: 
1- the wash material has insufficient tear strength.  
The strength of materials varies between manufacturers,  
& lower viscosity material is more likely to tear in the sulcus.  
2- When the sulcus is particularly deep, the wash material is thinner. 
3- removing the impression before the wash material is set. 
4- residue from provisional material 
5- insufficient retraction. 
Errors: 
 Poor impression with poor details → inaccurate final prosthesis. 
How to avoid: 
1- additional tissue retraction to widen the sulcus. 
2- choosing a more viscous wash material can help to improve the impression quality. 
6) Tearing: 
i) Poor tear strength 
ii) Immature removal from the mouth 
iii) Inadequate tissue displacement. 
 
8) Pulls & drags: 
1. Tray not centralized.  
2. Tray movement during seating. 
3. Tray movement during setting of impression material. 
4. Poor tray adaptation. 
5. Inadequate control of crevicular fluids. 
6. Exceed working time of impression. 
128
 
 
9) Inadequate tray adhesion: 
Distortion of the material i.e material shrinkage  remake  
10) Detachment of impression from tray: 
1- improper use of tray adhesive. 
2- use of tray with inadequate perforations.  
11) Lack of co-adaptation: 
i) No setting of the material 
ii) Latex contamination 
12) Impression relining:  
Avoid relining otherwise complete distortion may occur. 
13) Surface contamination (unset impression material): 
 a tacky unset layer of impression material, It may be due to: 
 
1- core build-up material, composites, or adhesives leaving a greasy coating on the 
tooth preparation. 
2- Re

            Quiz: