Permanent teeth eruption sequence

[Angle Jr.]

According to Woelfel, permanent teeth erupt in the following sequence:

1st (6-7 yr.): Mand. 1M, Max. 1M, Mand. Central
2nd (7-8 yr.): Mand. Lateral, Max. Central
3rd (8-9 yr.): Max. Lateral
4th (9-10 yr.): Mand. Canine
5th (10-12): Mand. 1PM, Max 1PM, Max 2PM
6th (11-12): Mand. 2PM, Max Canine

According to DentalStax, the sequence is:
(In the order of Central, Lateral, Can, 1PM, 2PM, 1M)
Max.: 4, 6, 12, 8, 10, 2
Mand.: 3, 5, 7, 9, 11, 1

But then I don't understand how the correct answer to the following question could be C:

Which of the following represents the third pair of permanent teeth to erupt in normal sequence?
A. Max. central incisors
B. Max. lateral incisors
C. Mand. lateral incisors
D. Mand. canines

Mandibular lateral incisors should be the at least the 4th pair to erupt, because there are 3 pairs that erupt earlier (i.e. Max. & Mand. 1M and Mand. central incisors).

I would appreciate it if someone could explain why the answer to the above question is C. Thank you.

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[manasa]

According to Woelfel, permanent teeth erupt in the following sequence:

1st (6-7 yr.): Mand. 1M, Max. 1M, Mand. Central
2nd (7-8 yr.): Mand. Lateral, Max. Central
3rd (8-9 yr.): Max. Lateral
4th (9-10 yr.): Mand. Canine
5th (10-12): Mand. 1PM, Max 1PM, Max 2PM
6th (11-12): Mand. 2PM, Max Canine

According to DentalStax, the sequence is:
(In the order of Central, Lateral, Can, 1PM, 2PM, 1M)
Max.: 4, 6, 12, 8, 10, 2
Mand.: 3, 5, 7, 9, 11, 1

But then I don't understand how the correct answer to the following question could be C:

Which of the following represents the third pair of permanent teeth to erupt in normal sequence?
A. Max. central incisors
B. Max. lateral incisors
C. Mand. lateral incisors
D. Mand. canines

Mandibular lateral incisors should be the at least the 4th pair to erupt, because there are 3 pairs that erupt earlier (i.e. Max. & Mand. 1M and Mand. central incisors).

I would appreciate it if someone could explain why the answer to the above question is C. Thank you.

I believe the answer is C 'coz it's the best possible choice .The third pair to erupt as per the data u provided is Mand centrals which is missing among the choices given. Also, teeth listed as A,B,D erupt only after the choice C. Hope this helps

 

[Angle Jr.]

Thanks for the reply. But how about max. central incisors? They erupt before mand. lateral incisors accrding to DentalStax. Woelfel (p.271) states that max. centrals and mand. laterals are "essentially a tie in eruption time." So I am still not sure why you can say that C is a better answer than A.

Also, can someone explain why the answer to the following question is C?

A 5-year-old child is treated with large doses of tetracycline over a one year period. Which of the following permanent teeth will least likely show tetracycline staining? (a) Permanent central incisors; (b) Permanent lateral incisors; (c) Permanent canines; (d) First premolars; (e) Permanent first molars

A. (a) and (b) only
B. (a), (b) and (c)
C. (b), (c) and (d)
D. (b), (c) and (e)
E. (c), (d) and (e)

According to the dentition development table in Woelfel, crown completion ages are:
Central incisors: 4-5 years
Lateral incisors: 4-5 years
Canines: 6-7 years
First premolars: 5-6 years
1M: 2.5-3 years

But I am not sure how I can answer this question.

I also have a general question. Is the only way to prepare for this kind of question to memorize exact values (e.g. 3-4 months, 4-5 years, 10-11 years, 10-12 years, etc.) for the entire dentition development table? I.e. for all of 1) initiation of calcification, 2) enamel completion, 3) eruption, 4) root completion, and 5) exfoliation? I would appreciate it if someone could give me advice on how I can prepare well for questions about dentition development. Thank you.

 

[dds_aspirant]

Thanks for the reply. But how about max. central incisors? They erupt before mand. lateral incisors accrding to DentalStax. Woelfel (p.271) states that max. centrals and mand. laterals are "essentially a tie in eruption time." So I am still not sure why you can say that C is a better answer than A.

Also, can someone explain why the answer to the following question is C?

A 5-year-old child is treated with large doses of tetracycline over a one year period. Which of the following permanent teeth will least likely show tetracycline staining? (a) Permanent central incisors; (b) Permanent lateral incisors; (c) Permanent canines; (d) First premolars; (e) Permanent first molars

A. (a) and (b) only
B. (a), (b) and (c)
C. (b), (c) and (d)
D. (b), (c) and (e)
E. (c), (d) and (e)

According to the dentition development table in Woelfel, crown completion ages are:
Central incisors: 4-5 years
Lateral incisors: 4-5 years
Canines: 6-7 years
First premolars: 5-6 years
1M: 2.5-3 years

But I am not sure how I can answer this question.

I also have a general question. Is the only way to prepare for this kind of question to memorize exact values (e.g. 3-4 months, 4-5 years, 10-11 years, 10-12 years, etc.) for the entire dentition development table? I.e. for all of 1) initiation of calcification, 2) enamel completion, 3) eruption, 4) root completion, and 5) exfoliation? I would appreciate it if someone could give me advice on how I can prepare well for questions about dentition development. Thank you.

Hi,
The best way to memorize the erruption charts is the same as you told.You can do one thing you can write down the erruption tables on a paper and read it everyday.It takes just abt 10 to 15 mints to read. This is what I did and by the day of your exam you ll be thorough with the tables.There is no othe alternative then to memorize them.
hope it helps.

good luck
ddsaspirant

 

[Angle Jr.]

Thanks for the advice, ddsaspirant. I'll try to memorize the chart by the exam day.

I figured out the tetracycline question. The teeth that are most likely to be affected are those which erupt at 6-7 years old, i.e. central incisors and 1M. The only choice that does not include either of these is choice C.

As for the first question I posted, I just checked the Kaplan explanation and it says "We disagree with the answer." The correct answer should be mandibular centrals. That question was not labelled as "ITEM NOT SCORED," but it seems that the question has no correct answer choice. Anyway, thanks for your help.

 

[manasa]

Thanks for the advice, ddsaspirant. I'll try to memorize the chart by the exam day.

I figured out the tetracycline question. The teeth that are most likely to be affected are those which erupt at 6-7 years old, i.e. central incisors and 1M. The only choice that does not include either of these is choice C.

As for the first question I posted, I just checked the Kaplan explanation and it says "We disagree with the answer." The correct answer should be mandibular centrals. That question was not labelled as "ITEM NOT SCORED," but it seems that the question has no correct answer choice. Anyway, thanks for your help.

Hi angle,

Are you sure that the answer choice C is the right one. Well I believe the answer should be E for the following reasons.

>. In the Q the child has been on Tc over a one yr period. Since yoa of the child is 5, we have to think that during 4-5 period he has taken medicine.

>. Tetracycline cause discolouration of teeth by chelating with Ca ions.this is most likely to happen during the calcification of teeth.So we need to think of calcification timings of tooth crown.( for Tc stains are mostly an esthetic issue)

>. From the calcification timing chart, central incisor's & laterals incisor's calcification is complete by age 5. but it is possible that it's complete by age 4. so these teeth are less likely to be affected.

>. Calcification of first molar crowns are complete by age 3 so these teeth are least likley to be affected by Tc in this case.

>.with respect to Pms and canines the calcification of crown completes only by age 7 so they are more likely to be affected by Tc.

 

[Angle Jr.]

Thanks for the reply, manasa. Your explanation makes sense. But the published answer is C (Q97, December 1988 exam). Here is what Kaplan explanation says:

"Tetracycline administered during crown formation will tend to discolor dentin in the affected tooth. The teeth to eliminate are those which will erupt as late as possible relative to the time when the tetracycline is being administered. Since the child is five years old, the teeth erupting at 6 or 7 will be most likely to show staining, and those erupting later are less likely. On average, central incisors erupt at 7 years, first premolars at 9 years, and first molars at 6 years. So choices a and e are most likely to be stained, while choices b, c, and d are least likely. So the correct answer to question 97 is choice 3."

When I read it carefully, this explanation does not make sense. Eruption ages do not exactly follow enamel completion ages. Since in this question we need to think about crown completion ages, rather than eruption ages, the above reasoning seems to be incorrect.

So the conclusion is that both ADA Joint Commission on National Dental Examination and Kaplan are giving a wrong answer on this question??? I hope things like this do not happen too often.

 

[manasa]

Hi,

I found a reason to sustantiate your answer. The rate of mineralisation of tooth is fast when it gets close to the age of eruption. So wrt Incisors and molars, more calcium is available to chelate tetracycline in these tooth, making it the more susceptible ones. Hope this explanation clarifies your doubt as well as mine.

Anyway, thx for ur response angle. Your reply helped me find the right reason

 

[Angle Jr.]

Thanks for the explanation, manasa. I had so much trouble with this question but it's clear now. I really appreciate your help.

 

[AbstractDentist]

which cusp of maxillary molars become progressively smaller?
i think it should be disto buccal
as distolingual is missing in 3 molars...
please correct me if i am wrong?