Oral Surgery

Negative effects on the cardiovascular system are not noted until blood levels of the local anesthetic are significantly elevated. But certain local anesthetics such as bupivacaine may precipitate potentially fatal ventricular firbrillation, and therefore is cardiotoxic at lethal doses.

Most common complication from posterior superior alveolar nerve block is hematoma, due to insertion of needle too far posteriorly into the pterygoid plexus of veins; in addition, the maxillary artery may be perforated.

Ilium provides excellent corticocancellous struts, which may be used as solid interpositional grafts to replace continuity defects in the mandible or osteotomy sites in the maxilla and mandible.
Ilium is a generous of cancellous bone. This cancellous bone, harvested alone, is used to fill large cavities such as maxillary alveolar defect in cleft lip and palate patients.

Syncope is a general term referring to a sudden, transient loss of consciousness that usually occurs secondary to a period of cerebral ischemia leading to cerebral hypoxia.

Most common complication from posterior superior alveolar nerve block is hematoma, due to insertion of needle
Too far posteriorly into the pterygoid plexus of veins; in addition, the maxillary artery may be perforated.

1. Buccal nerve, also known as the buccinator nerve and the long buccal nerve, usually passes between the two heads of lateral pterygoid to reach the external surface of that muscle.
2. It then follows the inferior part of the temporal muscle and emerges under the anterior border of the masseter muscle continuing in an anterolateral direction.
3. At level of the occlusal plane of the mandibular 3^rd/2^nd molar, it crosses in front of the anterior border of the ramus and enters the cheek through the buccinators muscle.
4. It is recommended that, therefore, during IAN injection, it is better to give separate long buccal nerve injection.
5. Better option is 'a' since all other nerves are there in pterygomandibular space.

The incision which is given at 45 degree to zygomatic arch, about 2 cm above the zygomatic arch,

1. Is about 2.5 cm long and is called as Gillies incision.
2. Is kept at 45 degree to zygomatic arch in the hairline in order to keep it parallel to anterior branch of the temporal artery.
3. Is used for reduction of zygomatic complex and isolated zygomatic arch fracture.

Insertion of lateral pterygoid muscle is as follows:

1. Part of the upper head, namely its uppermost and most medial fibres, is attached to the anteromedial surface of articular capsule and thus indirectly to the anterior border of the articular disc.
2. Majority of the fibres, i.e,  the greater part of the superior head and the entire inferior head, are inserted to a roughened fovea on the anterior surface of the mandibular neck.
   Therefore, muscle pulls the head of mandible and the articular disc forwards, downwards and inwards along the posterior slope of the articular eminence.
   Therefore, during fracture of condylar neck, condyle is displaced anteriorly and medially due to pull by lateral pterygoid muscle.

The pterygomandibular raphae (pterygomandibular ligament) is a tendinous band of the buccopharyngeal fascia, attached by one extremity to the hamulus of the medial pterygoid plate, and by the other posterior end of the mylohyoid line of the mandible.

The term horizontally favourable/unfavourable fracture is defined from the viewpoint of the observer and with respect to potential for displacement exhibited by the posterior fragment.
Therefore, horizontally unfavourable facture extends from the upper border (occlusal) of mandible downwards and backwards whereas horizontally favourable fracture extends from the upper border (occlusal) of the mandible downwards and forwards
These terms relate to the line of fracture at the angle ion. To get a clearer view, lateral oblique x-ray will be of choice.
(If lateral oblique x-ray is not there in the option, then OPG will be the second best option.)

Following radiotherapy, there are changes seen in the area that has undergone radiation. This is characterized by three Hs: hypocellularity, hypovascularity and hypoxia.
Extraction performed followed by radiotherapy in more prone to avascular necrosis of the socket bone due to these three Hs, which leads to decreased blood flow with decreased healing cells in combination with decreased oxygen leading to osteoradionecrosis.

Two principles must be adhered to, for entrance into the trachea.

1. the cricoid cartilage and 1^st tracheal ring must never be cut/ injured.
2. the incision into the trachea must not extend below the fourth tracheal ring.
   Therefore 2^nd and 3^rd tracheal rings are ideal site for tracheostomy.

Reasons for persistent paresthesia (persistent anaesthesia) are as follows:
a. Injection of a local anaesthetic solution contaminated by alcohol or sterilizing solution as these are irritant (alcohol is neurolytic)
b. Trauma to the nerve sheath produced by the needle during injection
c. Hemorrhage into or around the neural sheath can also cause paresthesia due to pressure over the nerve

Comminuted or grossly displaced fracture in body region with bone loss requires fixation with a locking reconstruction plate or standard reconstruction plate. Therefore, as in the question, if there is bone loss, the must appropriate option will be reconstruction plate, but if bone loss in not there, then Chamby's miniplate is the best option.

Long-acting local anaesthetic solution includes bupivacaine, ropivacaine, etidocaine and articaine.
If protein-binding of both bupivacine and ropivacaine is compared, then it is 95% and 94%, respectively. Also, clinical during of ropivacaine is 20% less than bupivacaine; therefore 'c' is the most appropriate answer.

Mucoperiosteal flaps are raised to render the operative site clearly visible and accessible to instrumentation. They are normally employed for providing access to bone to facilitate its removal in various surgeries like impaction, enucleation, etc.
Among the option given, most straightforward and simple best is choice '2'.

Cerebrospinal fluid leakage is important and suggests a more nasoethmoid or maxillary fracture extending through the cribriform plate.
Fracture involving the cribriform plate to the anterior base will lead to tear in dura causing CSF leak through nose.

Bilateral condylar fracture may result in
A. Marked anterior open bite and retrognathia.
B. The medial pterygoid and masseter muscles exert a superior posterior pull on the distal mandibular segment causing it to telescope past the condylar segments.
This telescoping result in premature contact in the posterior with rotation of the mandible around this point and anterior open bite.

Boiling point: -88.5^oC
Melting point: -90.8^oC
Relative density (water = 1): 1.23 at -89^oC
Solubility in water (g/100 ml at 15^oC: 0.15)
Vapour pressure (k Pa at 20^oC): 5150
Relative vapour density (air = 1): 1.53

The most common indication for removed of impacted teeth is recurrent pericoronoitis, pain, infection, etc., pericoronitis is the inflammation of the gingival surrounding a crown of a partially erupted tooth, therefore in order to avoid food lodgement with pericoronal infection and pain, the ultimate solution is removal of impacted teeth.
(Note that chronic periodontal disease and orthodontic treatment also warrant removal of impacted teeth under specific conditions, but they are not the commonest.)

The gold standard method of clinical bone mineral measurement, currently widely accepted is DX (dual energy x-ray absortimetry).
If showed significant correlation between bone density values in jaws and those of lumbar spine, femoral neck and foramen. In osteoporosis, density of bone mineralization is reduced due to calcium loss and is assessed effective on DXA.

Buccal nerve, also known as the buccinators nerve and the long buccal nerve, usually passes between the two heads of lateral of lateral pterygoid to reach the external surface of that muscle.
It then follows the inferior part of the temporal muscle and emerges under the anterior border of the masseter muscle continuing in an anterolateral direction.
At level of the occlusal plane of the mandibular 3^rd/2^nd molar, it crosses in front of the anterior border of the ramus and enters the cheek through the buccinators muscle.

A is the answer of choice. All standard local anaesthetics contain the preservative sodium bisulphate or metabisulphite. The preservative is necessary to keep the epinephrine fresh (epinephrine quickly deteriorates and loses potency otherwise).

Hypoglossal nerve is a somatic motor nerve, supplying all extrinsic and intrinsic muscles of tongue.
If there is hypoglossal nerve injury (due to penetrating injury to the neck and a skull base pathology), it causes the following:

1. Atrophy of ipsilateral muscle of the tongue and deviation towards the affected side with speech disturbance.
2. Deviation of tongue to right side as hypoglossal nerve on right side is injured.