5 Importance of primary teeth
- Proper development of muscles of mastication
- Formation of jaw bones - allow bone growth of dental arches
- Eventual location, alignment & occlusion of permanent teeth
- Maintain place for permanent teeth
- Resorption of deciduous roots guide erupting permanent replacements
Primate space
largest space between deciduous teeth
often found mesial to maxillary canines, distal to mandibular canines
Leeway space
difference between combined mesiodistal widths of primary canine, 1st & 2nd molars with permanent canine, 1st & 2nd premolars
maxilla: 0.9 mm per segment
mandibular: 1.7 mm per segment
Relationship of upper jaw to lower jaw
Centric relation
Relationship of upper teeth to lower teeth
Centric occlusion
3 Possible anteroposterior molar relationships of primary occlusion
- Mesial step
- Flush terminal plane
- Distal step
Maximum intercuspal position
point of tightest fit between maxillary & mandibular posterior teeth -> greatest surface area occurs
Other names for maximum intercuspal position
- Acquired centric occlusion
- Habitual occlusion
- Intercuspal position
3 Skeletal classifications
Class I: normal
Class II: retruded mandible
Class III: protruded mandible
3 Dental Classifications
Class I occlusal relationship: mesiobuccal cusp of maxillary 1st molar in line with buccal groove of mandibular 1st molar
Class II occlusal relationship: mesiobuccal cusp of maxillary 1st molar anterior to buccal groove of mandibular 1st molar
(Class II Division 1: normal/slightly protruded maxillary central incisor)
(Class II Division 2: retruded & inclined lingually maxillary central incisors)
Class III occlusal relationship: mesiobuccal cusp of maxillary 1st molar more posterior than normal to buccal groove of mandibular 1st molar
Group function
Pre-molars also occlude during lateral excursion
Premature contact area
posterior tooth hit slightly more than others
