A 10 year old male patient presents to the dental clinic with an avulsed tooth. There is a history of facial trauma while playing football. Examination of the avulsed tooth gave the following features:
Crown:

Buccal surface shows 3 cusps of equal size
Occlusal surface appears rectangular with a slight distal convergence of the crown.

Root:

Exaggerated flaring of the roots
Long  and slender
Primary 1st molar: Unlike the other primary teeth, the first primary molar does not resemble any of the permanent teeth. The mesial outline of the tooth, when viewed from the buccal aspect, is almost straight from the contact area to the cervical region. The distal area of the tooth is shorter than the mesial area. The two distinct buccal cusps have no evidence of a distinct developmental groove between them; the mesial cusp is the larger of the two. There is a pronounced lingual convergence of the crown on the mesial aspect, with a rhomboid outline present on the distal aspect. The mesiolingual cusp is long and sharp at the tip; a developmental groove separates this cusp from the distolingual cusp, which is rounded and well developed. The mesial marginal ridge is well developed, to the extent that it appears as another small cusp lingually. When the tooth is viewed from the mesial aspect, there is an extreme curvature buccally at the cervical third. The crown length is greater in the mesiobuccal area than in the mesiolingual area; thus the cervical line slants upward from the buccal to the lingual surface. The longer slender roots spread considerably at the apical third, extending beyond the outline of the crown. The mesial root, when viewed from the mesial aspect, does not resemble any other primary root. The buccal and lingual outlines of the root drop straight down from the crown, being essentially parallel for more than half their length. The end of the root is flat and almost square. 
Primary mandibular second molar: The mandibular second molar resembles the mandibular first permanent molar, except that the primary tooth is smaller in all its dimensions. The buccal surface is divided into three cusps that are separated by mesiobuccal and distobuccal developmental grooves. The cusps are almost equal in size. Two cusps of almost equal size are evident on the lingual surface and are divided by a short lingual groove. The primary second molar, when viewed from the occlusal surface, appears rectangular with a slight distal convergence of the crown. The mesial marginal ridge is developed to a greater extent than the distal marginal ridge. 
One difference between the crown of the primary molar and that of the first permanent molar is in the distobuccal cusp; the distal cusp of the permanent molar is smaller than the other two buccal cusps. The roots of the primary second molar are long and slender, with a characteristic flare mesiodistally in the middle and apical thirds.
Primary mandibular canine
Primary mandibular 1st molar
Primary mandibular 2nd molar
Permanent mandibular 1st molar