Dental and Oral Biology

All the agents have been used in the past in an attempt to extirpate pulp painlessly. But with the advent of local anesthesia, all these methods have been labeled inadequate, time consuming and archaic.

Compressed air must not be used for drying the root canal because tissue emphysema may result if an air bubble penetrates the periapical tissues. The emphysema may last as long as a week.

Sometimes a multirooted tooth has an untreatable periodontal lesion on one or more of its roots, but the remaining roots are healthy. So, to avoid extraction of the whole tooth that compromised root is removed which is called radisection.

A tooth whose restoration may require a post and core usually is filled with Gutta percha or sectional/split cone silver cone. The cone is notched 6 mm from the apical tip, and it is sterilized and is cemented in the root canal. The wedged cemented cone is rotated until it breaks at the notch, and the free end is removed to leave enough space for preparation of a post.

The root resorption causes maximum failures in replantation of avulsed teeth frequently followed by ankylosis. The two factors, which reduce the chances of failure by resorption are the reduction of extraoral time of the tooth to be less than 30 mts and the initiation of endodontic treatment a week after replantation. Endodontic treatment can be completed within six months of replantation.

Mitis-Salivarius-Bacitracin agar (MSA) with 20% sucrose and 0.2 U bacitracin/ml is a selective medium for streptococcus mutans. Bacitracin present in the medium suppresses the growth of most non-S.mutans colonies.

Dental cavities are formed due to the lack of fluorine.

A thin sticky film which is formed on the tooth, leading to tooth decay, is called plaque.

Yes, pulp cavity  is most inner part of the tooth, which contains both the blood vessels and nerve fibres.

Dentin is a calcified tissue of the body. It is covered by enamel on the crown and cemented on the rod and surrounds the entire pulp.

 Canines are sharp pointed teeth. These are called dog teeth as dog's dentition consist mostly of canines.

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.

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.

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.