Classification of 3rd Molar (Wisdom Teeth) Impaction

Systematic and meticulous classification of the position of impacted molar teeth helps in assessing the best possible path of removal of the impacted teeth and also in encountered during removal.

Prediction of operative difficulty before the extraction of impacted third molars allows a design of treatment that minimises the risk of complications. Both radiological and clinical information must be taken into account.

Factors such as sex, age, position of the molar tooth in relation to the occlusal plane and operative difficulty as judged by the surgeon, have all been reported to be associated with a significantly increased duration of postoperative recovery. It seems likely that patients judged to be at higher risk for delayed recovery will benefit from a more exhaustive postoperative follow-up and from specific post-operative measures to aid recovery.

Prediction of operative difficulty is therefore important for correct management. Various methods have been proposed for the pre-operative evaluation of difficulty but these have often been of limited validity. To overcoming the limitations of these systems, the classification systems can be used in conjunction with each other to determine the difficulty of removal of the impacted tooth

Classification of Impacted Mandibular 3rd Molars

• Based on the nature of the overlying tissues
• Winter’s classification
• Pell & Gregory’s classification

Based on the Nature of the Overlying Tissue

Based on the nature of the overlying tissue impaction, impacted lower wisdom teeth can be classified into:

• Soft Tissue Impaction. When the height of the tooth’s contour is above the level of the surrounding alveolar bone and the superficial portion of the tooth is covered only by soft (though this can be dense and fibrous) tissue. Soft tissue impaction is usually the easiest of type of impacted tooth to remove.
• Hard Tissue (‘Bony’) Impaction. This is where the wisdom tooth fails to erupt due to being obstructed by the overlying bone. This can be sub-divided into Partial and Complete Bony Impactions.
• Partial Bony. The superficial portion of the tooth is covered only by soft tissue but the height of the tooth’s contour is below the level of the surrounding alveolar bone. Apart from cutting the gingiva (gum) & possible bone removal from behind the tooth, the tooth’s roots may need to be divided.
• Complete Bony. The tooth is completely encased in bone so that when the gingiva is cut and reflected back, the tooth is not seen. Bone removal (large amounts) together with root sectioning will be needed to remove the tooth. These are often the most difficult tooth to remove.

Winter’s Classification

The classification is based on the inclination of the impacted wisdom tooth (3rd molar) to the long axis of the 2nd molar.