Mand_Third Molar

• The mandibular third molar varies considerably in different individuals and presents many anomalies both in form and in position.
• It supplements the second molar in function, although the tooth is seldom as well developed, with the average mandibular third molar showing irregular development of the crown portion, with undersized roots, more or less malformed.
• its design usually conforms to the general plan of all mandibular molars, matching more closely the second mandibular molar in the number of cusps and occlusal design than it does the mandibular first molar.
• Occasionally, mandibular third molars are seen that are well formed and comparable in size and development to the mandibular first molar.
• Many instances of mandibular third molars with five or more cusps are found, with the crown portions larger than those of the second molar
• In these cases, the alignment and occlusion with other teeth are not normal, because insufficient room is available in the alveolar process of the mandible for the accommodation of such a large tooth, and the occlusal form is too variable.
• Although it is possible to find dwarfed specimens of mandibular third molars, most of them that are not normal in size are larger than normal, in the crown portion particularly.
• Roots of these oversized third molars may be short and poorly formed.
• The opposite situation is likely in maxillary third molars. Most of the anomalies are undersized. Mandibular third molars are the most likely to be impacted, wholly or partially, in the jaw. The lack of space accommodation is the chief cause.
• If the third molar is congenitally absent from one side of the mandible or maxilla, it will most likely be absent from the other. However, no significant association is evident between third molar agenesis in the maxilla and mandible.
• Partial eruption of mandibular third molar teeth may result in periodontal defects on the distal aspects by the second molars and, in some instances, resorption of distal root surfaces occurs.
• When third molars are to be restored, it should be remembered that the depth of the enamel on the occlusal surface is relatively greater than that on first or second molars.
• Molar Patterns

  A) Protoconid

  B) Metaconid

  C) Hypoconid

  D) Entoconid

  E) Hypoconulid

  F) Sixth Cusp