Which tooth has maximum root surface area?

# Which tooth has maximum root surface area?
A. Maxillary first molar
B. Mandibular first molar
C. Maxillary canines
D. Mandibular central incisors

The correct answer is A. Maxillary first molar 

- Maxillary first molar has maximum root surface area (433 sq. mm) followed by mandibular first molar (431 sq. mm).

- Among posterior teeth, mandibular first premolars have least root surface area. (180 sq. mm)

- Among anterior teeth, maxillary canines have maximum root surface area. (273 sq. mm)

- Mandibular central incisor has the least root surface area of all teeth. (154 sq. mm)

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Ratio of the periodontal root surface area

# Ratio of the periodontal root surface area of the abutment teeth and the teeth to be replaced should be at least:
A. 1:1
B. 2:1
C. 1:2
D. 1:4

The correct answer is A. 1:1

According to Ante's law,  "Periodontal surface area of abutment teeth should be at least equal to the teeth replaced."

Ideal ratio is 2:1

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Reference points in endodontics in posterior teeth

# Reference points in endodontics in posterior teeth are:
A. Buccal and lingual surfaces
B. Pits
C. Cusp tips
D. Marginal ridges

The correct answer is C. Cusp tips.

Gross occlusal reduction should be done on any decayed or filled posterior tooth undergoing root canal therapy.

This reduction should be done before rubber dam placement to check occlusal clearance in all excursive movements. It should be done before the first endodontic treatment, rather than after, in order not to disturb cuspal reference points used to establish proper length of the tooth.

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Palatal root of maxillary first molar is curved:

# Palatal root of maxillary first molar is curved:
A. Mesially
B. Buccally
C. Lingually
D. Distally

The correct answer is B. Buccally.

Palatal root of upper first molar is often curved buccally at apical third. It has the largest  diameter and offers easiest access of all the three roots.

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Root canal of maxillary first molar difficult for instrumentation

# Root canal of maxillary first molar difficult for instrumentation is:
A. Mesiobuccal
B. Distobuccal
C. Distolingual
D. Mesiolingual

The correct answer is A. Mesiobuccal.

Mesiobuccal root has greatest distal curvature and is narrowest of all the three roots. It is flattened in mesiodistal direction. Sometimes, it contains a fourth canal. 

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Conditioning for GIC restoration

# In a cavity to be restored with GIC, it should be conditioned with:
A. Water
B. Polyacrylic acid
C. Phosphoric acid
D. Hydrochloric  acid

The correct answer is: B. Polyacrylic acid.

-Following completion of any cavity, there will be a smear layer left on the surface and floor.
- To remove this smear layer, 10% polyacrylic acid is applied and allowed to remain in place for 10 seconds.

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Endodontic Failure in Maxillary First Molar

# Most  common cause of endodontic failures in maxillary first molar is:
A. Missed fourth canal
B. Vertical root fracture
C. Periodontal involvement of pulpal lesion
D. None of the above

The correct answer is A. Missed fourth canal.

- It's a standard to mention now that's maxillary first molar has fourth canal, the MB2 in 54% of cases.

- The mandibular first molar is the tooth which needs RCT most commonly, but it's the maxillary first molar which has the most number of failed RCT.

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