2. Growth and development Flashcards
What is the bilaminar disc?
- ectoderm and endoderm
What is the trilaminar disc?
- endoderm, ectoderm and mesoderm
What does the ectoderm form?
- skin, nails, teeth etc
What does the mesoderm form?
Muscles, bone
What does the endoderm form?
- gut
What symptoms are present in ectodermal dysplasia?
- problem with ectoderm
- sparse hair
- periorbital wrinkling
- dysplastic nails
- congenitally absent teeth
- peg shaped teeth
What forms on the 26th day?
- frontal prominence
- maxillary process
- mandibular process
What forms on the 27th day?
- odontogenic epithelium
What forms on the 34th day?
- lateral nasal process
- medial nasal process
- nasal pit
What happens on 36th and 38th day?
Fusion of processes, eg. maxillary and mandibular process. And medial and lateral nasal process.
What happens in the 7th, 8th and 9th week?
- in the 7th week, the tongue is meant to drop down to allow the shelves to fuse correctly
- the primary palate is formed from the frontonasal processes, forming the premaxilla and fusing with the maxillary processes posteriorly
- the secondary palate is formed by fusing of the right and left palatal shelves of the maxilla
- failure of these processes to fuse gives rise to cleft lip/alveolus/palate
How does the mandible form?
from fusion of the bilateral prominences
What cartilage is the mandible made from?
- meckel’s cartilage forms the basis of the mandible as well as the structures of the inner ear
- therefore aberrations of the mandible can therefore lead to hearing difficulties and should be considered when faced with poorly developed mandible
How does a child’s mandible differ from adults?
Child’s mandible is smaller with a far shorter ramus
PHARYNGEAL ARCHES SLIDE 14
What is Treacher Collins syndrome?
Problem with the first pharyngeal arch
- eyes with downward slant
- small flattened cheekbones
- small steeply angled jaw
- small oddly shaped ears
- may have cleft palate
Where can clefts affect?
- the lip, alveolus and palate. If it affects the alveolus, the child may not have the full complement of teeth as the bone has not fused
- clefts of the mandible and face are very rare
What is the definition of a cleft?
Failure of developing palatal shelves and/or frontonasal prominence to fuse together
What is the incidence of clefts?
CLP- 1 in 7000 live births
Palate- 1 in 200
Who and where are clefts most common in?
Males and left hand side
What are associated syndromes with clefts?
- Downs syndrome
- Treacher Collisns
- Pierre Robin
- Klippel-Fiel
How does the mandible join and as a result which tooth is most likely to be missing?
- the mandible joins along the symphisis with left and right sides coming together. If there is a disruption in the union, it may cause absence of lower anterior 1
How does the maxilla join and as a result which tooth is most likely to be missing?
- the premaxilla joins the posterior maxilla at a region where the lateral incisors are
- so lateral incisor most likely to be missing if there is disruption in the union
What are morphogenetic fields?
- the arch is divided into segments
- the most anterior tooth in each segment is the key tooth, most stable
- eg, molars=6, premolars=4, anterior=1
- stability is in terms of reliable size and occurence
- this theory supports common patterns of hypodontia
What is the cranium like at birth?
- 60-65% of adult volume
- has sutures open
- has 6 fontanelles
What are the teeth like at birth?
- primary teeth are partly calcified
- teeth present at or very shortly after birth are called natal teeth
How does the mandible and maxilla grow?
In a downwards and forwards direction
When does the cranial base grow till and how?
- cranial base continues to enlarge at spheno-occipital synchrondosis
- till 15 years
- through endochrondral ossification
How does the maxilla grow?
By intramembranous ossification by enlargement of the sinuses
How does the mandible grow?
By intramembranous ossification as a result of muscle action and tooth development
What does a diolocephalic head shape form?
- face which is longer and thinner
- associated with high mandibular plane angle
What does brachycephalic head shape form?
- rounder faces more like a child
What is plagiocephaly?
Due to the result of premature fusion of one side of the cranium, giving lopsided growth
What are features of the primary occlusion?
- develops continuously from 7 to 29 months
- spaced incisors
- anthropoid spaces between b’s and c’s
- flush terminal plane
- primary teeth are whiter and more susceptible to erosion than the permanent dentition
What is the eruption sequence for primary teeth?
- lower A
- upper A, upper B, lower B
- D
- C
- E
What dates do A and B erupt?
6-9 months
What dates do D erupt?
12-14 months
What dates do C’s erupt?
16-18 months
What dates do E’s erupt?
20-30 months
What is the definition of the leeway space?
the difference between the sum of the mesiodistal crown widths of the primary canines and molars and that of their successors, the permanent canines and premolars.
- the difference in width between the distal aspect of E and mesial aspect of CW
What is the upper leeway space?
1.5mm
What is the lower leeway space?
2.5mm
What is the gingivae around primary teeth like?
- gingivae around primary dentition has pocket depth of around 3mm compared to 2mm for permanent
What are the soft tissues in the primary dentition like?
- epithelia thinner with less keratinisation
- sulci deepen from birth till adulthood
- fraenae become less prominent
Which layer is soft tissues of the mouth derived from?
ectoderm
When does post natal growth occur most?
0-5 years marks the greatest growth
- second growth spurt at onset of puberty
What are the symptoms of Goldenhar syndrome?
- tags on ears
- flat nasal bridge
- facial asymmetry
- midface deficiency
- deviated angle of mouth
- canting
- loss of xygomatic and malar prominence
When is growth of the brain and cranium complete by?
5 years
Which permanent teeth calcify at birth?
first permanent molars and incisors
When does the face stop growing?
Face grows forwards and downwards till the early 20’s
What drugs should you avoid in pregnancy?
- NSAID’s and benzodiazepines
How long is pregnancy?
38 weeks
Smoking, drinking alcohol and taking recreational drugs is strongly discouraged
What is prescribed during pregnancy?
Folic acid to prevent spina bifida and similar diseases
What is given parentrally in the neonate and at what time point?
Vitamin K parentral
0-4 weeks
What is screened 0-4 weeks in a baby?
- rhesus test of the umbilical cord
- hearing test
What is physically examined at 0-4 weeks in baby?
- eyes, heart, hips, testes
What is the heel prick test/blood test done for?
Done at 0-4 weeks
- to test sickle cell
- cystic fibrosis
- congenital hypothyroidism
- inherited metabolic disease
What is prematurity?
- when a baby is born less than 34 weeks gestation
- more than 32 weeks have excellent outcomes
- 23-26 weeks have significant problems
What 3 common problems occur in prematurity?
- respiratory distress syndrome
- hypotension
- patent ductus arteriosis
When do children in the uk have health visitors?
- up until 5 years old
- supports family and monitors growth of the child
Which medical interventions and people help with the child?
- health visitor
- vaccinations
- school nurse
- social worker
- paediatrician
- dietician
- speech and language therapist
What is failure to thrive?
- failure of the baby to put weight on and grow
- most often linked with feeding difficulties, absorption difficulties
What 3 things do you use to diagnose failure to thrive?
- growth that has dropped over 2 or more percentiles
- persistently below the third or fifth percentile
- less than 80% percentile for median weight for height measurement
41-49
