Dentosphere : World of Dentistry

 # 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) 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). Inter...

 # 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: 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)

 # The free gingival groove is most commonly associated with which tooth?  a) Maxillary canine  b) Mandibular incisor  c) Maxillary first molar  d) Mandibular premolar The correct answer is: b) Mandibular incisor The free gingival groove is a shallow linear depression that demarcates the free gingiva from the attached gingiva. It is more prominent in some individuals and may not always be present. However, when it is visible, it is most commonly associated with the mandibular incisors due to their relatively thin and well-defined gingival anatomy.  This aligns with standard dental textbooks like  Carranza’s Clinical Periodontology , which highlights the mandibular incisors as a common site for the free gingival groove.

 # Well aligned deciduous dentition is an indication of: A. Potential crowding B. Disto occlusion C. Mesio occlusion D. Well aligned permanent teeth The correct answer is: A. Potential crowding Explanation: Well-aligned deciduous dentition (primary teeth) with little to no spacing  is often a predictor of  potential crowding  in the permanent dentition. Primary teeth are smaller than permanent teeth, and deciduous arches typically exhibit natural spacing ("primate spaces") to accommodate the larger permanent successors. If primary teeth are tightly aligned, it suggests insufficient space for the eruption of larger permanent teeth, increasing the risk of crowding. D. Well-aligned permanent teeth  is incorrect because spaced (not tightly aligned) primary teeth are actually a better indicator of sufficient arch space for proper alignment of permanent teeth. B. Disto-occlusion  and  C. Mesio-occlusion  refer to malocclusions (Class II and Class III bi...

 # The palate is considered the most appropriate insertion site for miniscrews supporting an intraoral distalizer because it: a) is free of dental roots and other anatomical structures b) does not create a force vector passing coronally to the maxillary arch’s center of resistance c) takes advantage of bicortical anchorage d) all of the above The correct answer is D.  All of the above Explanation: The palate is an ideal site for miniscrew-supported intraoral distalizers because of the following advantages: Free of dental roots and other anatomical structures (Option a) The mid-palatal region is a safe zone with minimal risk of damaging dental roots or vital structures, making it ideal for miniscrew placement. Does not create a force vector passing coronally to the maxillary arch’s center of resistance (Option b) Placing miniscrews in the palate helps direct force closer to the center of resistance of the maxillary arch , reducing unwanted tipping or extrusion effects. Takes ...