Dental and Oral Biology

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.

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.

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'.

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.

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.)

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.

Stability is defined as the quality of prosthesis to be firm, stable or constant and to resist displacement by functional, horizontal or rotational stresses.

The arrangement of posterior teeth depends on ridge shape, ridge relation and other anatomical factors where as arrangement of anterior teeth is governed by esthetics and phonetics.

Bruxism/habitual clenching or grinding is prevented by an appliance called mouthguard in patients.

A flexible major connector due to lack of rigidity can allow lateral flexure under occlusal forces, which may induce torque.

Mouth guards are worn usually by all persons engaged in contact sports to prevent any injury to the teeth and surrounding tissues.

An edentulous space can occur on both sides of a tooth creating a lone pier abutment.

The anterior vibrating line is always located on soft palatal tissues. 

Hinge axis is an imaginary line passing through the centre of condyles around which the mandible rotates in sagittal plane and this position is also called 'Terminal hinge position'.