Relation between the cusps and roots of mandibular third molars

[Objective] This work is to study the relationship of mandibular third molars between the number of dental cusps and that of roots.[Methods] Two hundred and ten extracted mandibular third molars were collected.The number of cusps and roots was directly observed and analyzed.[Results](1)The mandibular third molars that had 4 or 5 cusps was 79.53%.The mandibular third molars which had 5 cusps and 2 roots was 56.86%.(2)The number of the dental roots may increase when the cusps increased.[Conclusion] The number of the roots should be evaluated possibly before the mandibular third molars are extracted.