Mandibular First Molar Group 7
Primary Tooth eruption facts: • Girls generally precede boys in tooth eruption • Every 6 months of life, approximately 4 teeth will erupt. • Lower teeth usually erupt before upper teeth • Teeth in both jaws usually erupt in pairs.One on the right and one on the left • By the time a child is 2 to 3 years of age, all primary teeth should have erupted
Characteristics of Deciduous Mandibular First Molars • The crowns are bulging buccally and lingually at the cervical rim • Thinner enamel and dentin • Cervical area is constricted • Will emerge in about 14 to 18 months. It will shed off in about 9 to 11 yrs.
Characteristics ofDeciduous Mandibular First Molars • Smaller in size and whiter in color than the permanent teeth. • Longer and more slender roots in relation to crown size • Has a prominent mesio-buccal cervical bulge
Function • The mandibular molars are the largest and strongest teeth in the lower jaw.Its main role is for mastication.
Function • It reserve space for their permanent counterparts. • It gives the face its normal appearance. • It aids in the development of clear speech.
Function • It helps attain good nnutrition • It helps give a healthy start to the permanent teeth
Problem Associated with Eruption: Ankylosis is caused by the fusion of the cementum of the root to the bone and accompanying loss of periodontal ligament attachment. One of the most commonly affected tooth is the primary mandibular first molar.
Ankylosis can lead to: Loss of arch length Extrusion of teeth of the opposite arch Interference with the eruption of succedaneous teeth
Treatment - Placement of a stainless steel crown over the ankylosed tooth. - Extraction
Buccal AspectClass traits and type traits • Mesial outline of the crown is almost straight. • Distal portion of the crown is shorter than the mesial portion.
Buccal AspectClass traits and type traits • Two buccal cusp is distinct.No developmental groove. • Mesial cusp is larger than the distal cusp • Roots are long and slender
Lingual AspectClass traits and type traits • Distolingual cusp is rounded • Mesiolingual cusp is long and sharp at tip • Mesial marginal ridge is well developed
Lingual AspectClass traits and type traits • Part of the two buccal cusps may be seen from this angle • Crown length mesially and distally is more uniform than it is from the buccal aspect • Cervical line is straighter
Mesial AspectClass traits and type traits • The most noticeable detail from the mesial aspect is the EXTREME CURVATURE bucally at the cervical third.
Mesial AspectClass traits and type traits • Crown outline resembles the mesial aspect of of the primary 2nd molar and the mesial aspect of the permanent mandibular molars.
Mesial AspectClass traits and type traits • Both the MB cusp and ML cusp are in view from this aspect , as is the well-developed mesial marginal ridge.
Mesial AspectClass traits and type traits • Since the mesiobuccal crown length is greater than the mesiolingual crown length, the cervical line slants upward buccolingually.
Mesial AspectClass traits and type traits • The buccal and lingual outlines of the root drop straight down from the crown and are approximately parallel for over half their length, tapering only slightly at the apical third. • The root end is flat and almost square.
Mesial AspectClass traits and type traits • A developmental depression usually extends almost the full length of the root on the mesial side.
Distal AspectClass traits and type traits • The cervical line does not drop buccally. • The length of the crown buccally and linguallyis more uniform. • The cervical line extends almost straight across buccolingually.
Occlusal AspectClass traits and type traits • General outline is RHOMBOIDAL. • It accents the mesiobuccal line angle of the crown in comparison with the distobuccal line angle.
Occlusal AspectClass traits and type traits • The mesiolingual cusp may be seen as the largest and the best developed of all the cusps, and it has a broad flattened surface lingually.
Occlusal AspectClass traits and type traits • The buccal developmental groove of the occlusal surface divides the two buccal cusps evenly.
Occlusal AspectClass traits and type traits • The central developmental groove separates the mesiobuccal cusp and the mesiolingual cusp.
Occlusal AspectClass traits and type traits • The central groove ends in a mesial pit in the mesial triangular fossa, which is immediately distal to the mesial marginal ridge.
Occlusal AspectClass traits and type traits • The lingual developmental groove separates the mesiolingual cusp and the distolingual cusp.