JVD 2020 #3 Morphology of the Cementoenamel Junction in Permanent Teeth of Dogs: A Scanning Electron Microscopic Study; Hernandez

Question 1

What are Choquet cases of cementoenamel junction morphologies

Answer 1

Types of human CEJ morphology (4 types)

Question 2

What is type 1 CEJ morphology

Answer 2

The cementum overlaps the enamel

Question 3

What is type 2 CEJ morphology

Answer 3

The enamel overlaps the cementum

Question 4

What is type 3 CEJ morphology

Answer 4

Cementum and enamel are edge-to-edge

Question 5

What is type 4 CEJ morphology

Answer 5

Gap between the enamel and cementum with exposed dentin

Question 6

What was the most prevalent type of CEJ morphology in dogs?

Answer 6

Type 3, either alone or in combination, 90.7% of samples

Question 7

What was the 2nd most prevalent type of CEJ morphology in dogs?

Answer 7

Type 4, gap with exposed dentin. Present in 31.58% of samples

Question 8

How many teeth samples showed only one type

Answer 8

65.13%

Question 9

How many teeth samples showed a combination of types?

Answer 9

34.87%

Question 10

The CEJ of dogs evaluated showed a high degree of variability in:

Answer 10

different types of teeth
within a same tooth
within the dentition of a single individual
and among individuals

Question 11

Which type of CEJ morphology?

Answer 11

Type 1- Cementum overlapping the enamel

Question 12

Which type of CEJ morphology?

Answer 12

Type 2- Enamel overlapping cementum

Question 13

Which type of CEJ morphology?

Answer 13

Type 3- Edge-to-edge relationship between the cementum and enamel

The most common type in dogs (alone or in combo) 90.79% of samples

Question 14

Which type of CEJ morphology?

Answer 14

Type 4- Gap between the enamel and cementum with exposed dentin.

Second most common type in dogs- 31.58% (alone or in combo)

Question 15

What causes an irregular limit of cervical enamel in its marginal edge and an irregular onset of the formation and deposition of cementum?

Answer 15

Non-uniform fragmentation of Hertwig’s epithelial root sheath.

Question 16

What is Hertwig’s epithelial root sheath?

Answer 16

The enamel organ gives rise to Hertwig’s epithelial root sheath which is 2 epithelial layers: inner and outer epithelium. After enamel formation, the sheath irregularly fragments in time and space promoting deposition of cementum onto the newly formed dentin. After fragmentation, it participates in cementogeneis and formation of the periodontal ligament, giving rise to epithelial rests of Malassez.

Question 17

CEJ type 2 (enamel covering cementum) should not be embryologically possible, why?

Answer 17

Because development of the enamel ceases before that of the cementum. Those seen in the study were only in small segments or some kind of enamel strips on the cementum. These regions may be explained by existence of a hyperactive Hertwig’s sheath as it happens in formation of enamel pearls.

Question 18

In DeLaurier et.al. Analysis of the characteristics and mineralization status of feline teeth using scanning elecron microscopy. J Anat. 2006 , what type of CEJ was most common in cats and how does this relate to pathology?

Answer 18

Type 4 CEJ (gap between E &C) was most common followed by type 3 (edge-to-edge).

Suggested a possible relationship between the presence of exposed dentin and development of resorptive lesions.