The first evidence of cartilage getting converted to bone in craniofacial skeleton occur during:

 # The first evidence of cartilage getting converted to bone in craniofacial skeleton occur during:

A. Fourth postnatal week

B. Eighth prenatal week

C. Fourth prenatal week

D. Eighth postnatal week

The first evidence of cartilage converting to bone (endochondral ossification) in the craniofacial skeleton occurs during the eighth prenatal week. This timing aligns with the development of the cranial base (e.g., occipital, sphenoid, and ethmoid bones), which undergoes endochondral ossification. While mesenchymal condensations and cartilage models form earlier, the actual replacement of cartilage by bone begins around this period, marking the start of ossification in these regions.

Answer: B. Eighth prenatal week

Simple retraction of maxillary incisors using maxillary molars as anchorage is an example of: PGCEE MDS 2025

 # Simple retraction of maxillary incisors using maxillary molars as anchorage is an example of:  (PGCEE MDS 2025)

a) Simple anchorage 

b) Reciprocal anchorage

c) Stationary anchorage 

d) Intermaxillary anchorage

The correct answer is:

c) Stationary anchorage

Explanation:

Stationary anchorage refers to a type of anchorage where the resistance to unwanted tooth movement is achieved by using teeth that undergo minimal movement, usually due to bodily movement rather than tipping.

• In simple retraction of maxillary incisors using maxillary molars as anchorage, the molars provide resistance while the incisors move posteriorly. The molars remain relatively stable, which characterizes stationary anchorage.
• Other types of anchorage:
  • Simple anchorage – Resistance to movement provided by the PDL of the anchoring teeth.
  • Reciprocal anchorage – Two equal and opposite forces are applied, leading to movement of both units (e.g., space closure between two adjacent teeth).
  • Intermaxillary anchorage – Anchorage derived from teeth in the opposite arch (e.g., elastics from maxillary to mandibular teeth).

Serial extractions are indicated when there is - PGCEE MDS Entrance 2025

 # Serial extractions are indicated when there is -

a) No skeletal discrepancy with dental crowding > 10 mm

b) No skeletal discrepancy with dental crowding between 5 - 7 mm.

c) Skeletal discrepancy >5°

d) Skeletal discrepancy >10° with dental crowding < 5mm

The correct answer is A. No skeletal discrepancy with dental crowding > 10 mm

 Serial extraction is indicated in cases of severe dental crowding. For this reason, it is best used when no skeletal problem exists, and the space discrepancy is large i.e., >10 mm per arch.

If the crowding is severe, little space will remain after the teeth are aligned, which means there will be little tipping and uncontrolled movement of the adjacent teeth into the extraction sites. If the initial space discrepancy is smaller, more residual space must be anticipated.

The commonest teeth involved in transposition are: PGCEE MDS Entrance 2025

 # The commonest teeth involved in transposition are:

a) Maxillary central incisor and lateral incisor

b) Maxillary canine and first premolar

c) Maxillary 1st premolar and 2nd premolar

d) Maxillary canine and Lateral incisor

The correct answer is:

b) Maxillary canine and first premolar

Explanation:

Tooth transposition is a rare developmental anomaly where two adjacent teeth exchange their positions within the dental arch. The most commonly involved teeth in transposition are the maxillary canine and first premolar. This occurs due to disturbances in tooth eruption patterns, genetics, or space constraints in the dental arch.

Other less common transpositions include:

• Maxillary canine and lateral incisor (less frequent but still observed)
• Mandibular canine and lateral incisor (rare)