Tooth Morphology: Primary Teeth (2024-25) PDF

8/8/2023 Objectives By the end of this plenary you will: Tooth morph...

8/8/2023 Objectives By the end of this plenary you will: Tooth morphology: primary dentition Be able to describe the eruption sequence of the primary dentition A/Prof Nicky Kilpatrick Know how the morphology of primary teeth differs from that of permanent teeth BDS PhD FDS RCPS FRACDS (Paeds) Understand the potential implications of these differences on clinical practice [email protected] 1 2 The primary dentition Primary Dentition Development starts at 7 weeks in utero 20 teeth: 10 maxillary & 10 mandibular – 4 incisors: Eruption begins @ 6 months of age – 2 canines: Dentition is complete @ 2.5 yrs of age – 4 molars: 3 4 Primary dentition Primary dentition Canines Incisors Upper right Upper left { edcba abcde edcba abcde edcba abcde edcba abcde Lower right Lower left Molars 5 6 1  8/8/2023 Primary dentition Timing of eruption & exfoliation Incisors Arch Primary tooth Eruption Exfoliate/yrs Central Lateral starts/mnths lower a central incisor 6 – 10 6–7 upper a central incisor 8 - 12 Canines upper b lateral incisor 9 - 13 7-8 lower b lateral incisor 10 - 16 First Molars upper d first molar 12 - 18 9 - 11 Second lower d first molar 14 - 18 upper c canine 16 - 22 10 - 12 lower c canine 18 - 24 upper e second molar 22 - 33 10 - 12 lower e second molar 24 - 31 See Welbury et al. Paediatric Dentistry 5th Ed. Page 12 7 8 Primary dentition eruption Primary dentition eruption Starts @ around 6 months 6 - 12 months b a a b – lower central incisors – all 4 incisors – lower a’s – a’s and b’s b a a b Right Left Right Left a a b a a b 9 10 Primary dentition eruption Primary dentition eruption 12 - 18 months b a a b 18 - 36 months b a a b – incisors: a’s and b’s – incisors: a’s and b’s c c – 1st molars: d’s – 1st molars: d’s – canines: c’s d d d d – 2nd molars: e’s e e d b a a b d Right Left d b a a b d e d c b a a b c de Right Left e d c b a a b c d e 11 12 2  8/8/2023 Primary dentition: 3 years of age Eruption patterns: what to look for Significant variation in timing of eruption – BUT generally chronological and symmetrical Pay attention to: – order e.g. if d’s erupt before the a’s etc – symmetry i.e. one side much later than the other Even greater variation in exfoliation patterns – premature exfoliation should be investigated – particularly without associated root resorption 13 14 Common anomalies Morphology: primary vs permanent Natal teeth Crown morphology Root morphology – present at or soon after birth – thin splayed roots – thinner enamel and – usually a lower incisor – shallow pulpal floor dentine layers – may cause feeding issues – multiple canals – narrow occlusal table Eruption cyst – shorter clinical crowns – dentigerous cyst – broad flat interproximal contact areas 15 16 Primary vs permanent teeth Primary vs permanent teeth Crown morphology Clinical significance Crown morphology Clinical significance – caries progresses to – thinner enamel and – less space for restorative – thinner enamel and pulp more quickly dentine layers bulk dentine layers – easier pulp exposure 17 18 3  8/8/2023 Primary vs permanent teeth Primary vs permanent teeth Crown morphology Clinical significance Crown morphology Clinical significance – narrow occlusal table – B-L width of cavity – shorter clinical crowns – difficulty fitting matrix needs to be reduced bands 19 20 Primary vs permanent teeth The primary dentition Crown morphology Clinical significance Caries diagnosis – broad flat interproximal – problems with caries contact areas diagnosis 21 22 The primary dentition Primary vs permanent Root morphology 10 – 60% of lesions remain undetected without BWs 23 24 4  8/8/2023 Primary vs permanent Primary vs permanent Root morphology Clinical significance Root morphology Clinical significance – thin and splayed – endodontic Rx – thin pulpal floor – perforation risk – fracture risk – multiple canals – inter-radicular vs Upper d Upper e periapical lesions Lower d Lower e 25 26 Summary 20 teeth – incisors, canines and molars: a - e Eruption – starts @ 6mnths and finishes @ 2.5yrs of age – generally chronological and symmetrical Morphology differs to permanent teeth – impacts clinical management See Welbury et al. Paediatric Dentistry 5th Ed. Page 12 [email protected] 27 5