100+ Free CMSA Diploma in Oral Surgery Dip Oral Surg(SA) Practice Questions

Explanation: Winter's classification categorizes mandibular third molar impactions based on the inclination of the third molar's long axis relative to the second molar. A mesioangular impaction is defined by a mesial tilt between 11 and 70 degrees towards the second molar, making it the most common and generally easiest type of impacted third molar to remove in the mandible.

Explanation: The lingual nerve lies in close proximity to the lingual cortical plate and periosteum distal to the mandibular second molar in up to 15-20% of cases. Making incisions on the lingual aspect or extending retromolar incisions too far lingually creates a severe risk of direct transaction or neuropraxia of the lingual nerve.

Explanation: Articaine is unique among amide local anaesthetics because it contains a thiophene ring instead of a benzene ring, as well as an ester side group. This ester group allows rapid hydrolysis by plasma esterases (half-life ~20 minutes), resulting in lower systemic toxicity despite its 4% concentration.

Explanation: Alveolar osteitis (dry socket) is caused by premature disintegration or breakdown of the post-extraction intra-alveolar blood clot. Tissue and bacterial plasminogens activate plasmin, which lyses the fibrin framework, exposing denuded alveolar bone and sensory nerve endings.

Explanation: A dentigerous (follicular) cyst develops by fluid accumulation between the reduced enamel epithelium and the enamel crown of an unerupted tooth. Radiographically, it presents as a well-circumscribed radiolucency attached at the cementoenamel junction (CEJ) of the impacted tooth.

Explanation: Extraoral submandibular incision and drainage must be performed at least 1.5 to 2 cm below the inferior border of the mandible (or in a natural skin crease) to prevent damage to the marginal mandibular branch of the facial nerve. Hilton's blunt dissection technique is then used once through skin and platysma.

Explanation: The maximum safe recommended dose for plain Lignocaine (without vasoconstrictor) is 4.4 mg/kg in adults, not exceeding an absolute maximum of 300 mg. When epinephrine is added, the increased local retention allows the maximum dose to be increased to 7.0 mg/kg (up to 500 mg).

Explanation: The Cryer elevator features a sharp triangular blade angled at 90 degrees to the shank. It is used primarily in double-rooted mandibular molars when one root has been removed, inserting the tip into the empty socket to wheel-and-lever out the adjacent remaining root.

Explanation: The submandibular space lies inferior to the mylohyoid muscle and superior to the deep layer of cervical fascia. Odontogenic infections originating from lower second and third molars perforate the lingual cortex below the mylohyoid ridge directly into the submandibular space.

Explanation: When a root tip displaces toward or into the maxillary sinus, radiographic imaging (intraoral periapical or CBCT/panoramic) must be obtained immediately to verify whether the root tip is subperiosteal under the sinus membrane, free within the sinus cavity, or still inside the socket.