Everything you wanted to know about DA and Occlusion!

[gpg]

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OK people

here we go with my lectures on DA and Occlusion as I had promised.Now since I am also studing and working in the clinic so I cannot devote too much time at a stretch for this.....so I will go in phases.

Before I begin I have a request.Please do not send your querries,suggestions comments on this thread......so that I can maintain my continuity with the topics.I will be starting another thread titled doubts for DAO for gpg......please send all your doubts there.

Thanks

 

[gpg]

Now you will need only two things to master DAO:

1)The decks....I have been refering the 2001 version.So that will be good enough.

2)The ASDA reprints......the ones I have are till 1996


So lets start with the topic about which I did not know ANYTHING till I started studing for my boards.And I used to go crazy trying to figure them out.

Mandibular Movements

Now basically there are only 2 movements....
A)The Functional Mandibular Lateral Excursion.
B)Mandibular Protrusion.

But since the mandible is a bilateral joint,there are two sides to consider in the lateral movement.

1)the working side:this is the side to which the mandible is moving.

2)Non-working side:The other side.....thats the side from which the mandible is moving away from.

How do you determine which is the working side and the non-working side looking at the arrows on the text?

SIMPLE!

When the arrow is exactly horizontal......pointing towards the lingual on mandibular and buccal on the maxillary teeth it is a WORKING SIDE MOVEMENT!

Now I am sure all of you will be able to determine the side looking at the occlusal surfaces of the teeth shown.

So when there is a Horizontal arrow that is a working side movement of the same side.

1)Imagine a diagram showing the occlusal surfaces of the lower right posteriors.The arrow is exactly straight pointing towards the lingual,then the movement is a working side movement to the right side.

2)When the occlusal surfaces of the upper left posteriors is shown with the arrows pointing to the buccal, its a working side movement to the left.

As simple as that!

Now in case of the non-working side movements,the arrow is obliquely directed.

The Mandibular cusps move mesially and lingually and the Maxillary teeth move distally and facially.

So if u have the occlusal surfaces of the lower right posteriors with the arrow pointing distofacially its a non-working side movement to the right(see 1 above)

and similarly if you have the occlusal surfaces of the upper right posteriors with the arrow pointing to the mesiolingually its the non-working side movement to the left....see 2 above!

Remember the arrows do not depict the movement of the cusps shown.They indicate the direction the occluding cusps move in the respective movement

so in 1 even though u have the lower right teeth shown with the arrow pointing to the lingual, it does not mean that the lower teeth are moving lingually.It means that the occluding teeth, viz. the upper right teeth are moving lingually against the lower teeth.

The protrisive movement is very easy to understand, as there is no working and non-working side confusion here.

just remember the direction of the arrow on the respective teeth.....it will point anteriorly on the maxillary and posteriorly on the mandibular teeth.

VERY ZIMBLE.......as my mallu geography teacher would have said it.

so now I would like you all to get out your reprints first, read only the questions with the occlusal surfaces of teeth and arrows on them.....and try to solve them using this key which I have given.You all have to get them right.

a very simple way to do it is to make a chart in the following format

Direction of arrow on the working side as shown on following teeth:

1)maxillary 2)Mandibular

buccally lingually

and draw diagrams showing the movement and direction of movement of cusps.

do the same thing for the non working side....and put it up on the mirror......you will surely master this aspect within a week,unless you are bald....in which case you have to put it somewhere u will see it the most......

There is a lateral-protrusive movement, but I think there is only one question showing this movement so I will not include this here as it is very confusing and not too important.

hope I have not bored you all with this.

Please let me know what you feel about my tutorial, whether it has helped you in any way and whether you would like me to make any changes in the next one....

happy mandibular movements!

 

[gpg]

please do not post any comments on this thread....use the other thread I have started for the same.....thanks

 

[gpg]

Well here we are with the next tutorial

we will have a look at the actual occlusion of our teeth,
mainly the posteriors:

lets start with the Maxillary cusps.

1)Buccal cusps:-

Maxillary buccal cusps occlude only with grooves and embrassures of
class counterpart or class counterpart and tooth distal to it.

A)The cusp of the canine lies in the facial embrassure b/w the
mandi canine and pre-molar.

It is unique in that it is the only tooth which overlaps teeth in
both the anterior and posterior segment.

How ever the TIP does not articulate with any tooth.

B)Ist Pre-molar:-

It occludes with the facial embrassure b/w mandi pre-molars.

C)IInd Pre-molar:-

It occludes with facial embrassure b/w 2nd PM and 1st molar.

D)Ist Molar:-

MB Cusp:MB groove of mandi 1st molar

DB CuspB groove of mandi 1st molar

Oblique Ridgeeve. Groove b/w DB and Distal cusp of mandi 1st Molar

E)IInd Molar:

MB Cusp:MB groove of mandi 2nd molar

DB Cusp:Embrassure b/w mandi 2nd and 3rd molar.

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Lets now go on to the Lingual cusps:

These occlude with Fossae and Marginal Ridges of class counterpart or
class counterpart and tooth distal to it.

A)Ist Pre-Molaristal triangular fossa of mandi 1st PM.

B)IInd Pre-Molaristal triangular fossa of mandi 2nd PM

C)Ist Molar:

-ML Cusp:Central Fossa of mandi 1st molar

-DL Cuspistal Marginal Ridge of 1st molar and
Mesial Marginal Ridge of 2nd molar

D)IInd Molar:

-ML Cusp:Central Fossa of mandi 2nd molar

-DL Cuspistal Marginal Ridge of 2nd molar and
Mesial Marginal Ridge of 3rd molar

Imp Notes:

The TIPS do not occlude with any tooth.

Also it is the triangular ridge of the maxillary cusps which are resting in the sucli and embrassures of the mandibular teeth.....there are a couple of questions about this point too...

I think I have covered almost everything about the maxillary cusps.....the tut on mandibular cusps will be uploaded in a day or two....

 

[Henna]

gpg,
You can post this in the tutorial thread.

Henna

 

[gpg]

OK ppl its occlusion time.....

this time we will be having a closer look at the mandibular cusps.....and where they leave their mark...

A)Buccal cusps:

They occlude into central/mesial/distal fossae of their class counterpart or onto the marginal ridges of their counterpart and the tooth mesial to it.

lets go tooth wise...

1)Ist Pre-molar: Mesial triangular fossa of maxillary 1st PM
and Distal Marginal Ridge of Canine

2)IInd Pre-molar: Mesial triangular fossa of 2nd PM

3)Ist Molar:

-MB cusp: Mesial marginal ridge of 1st molar
and Distal marginal ridge of 2nd PM

-DB cusp: Central fossa of 1st molar

-Distal cusp: Distal triangular fossa of 1st molar

4)IInd Molar:

-MB cusp: MMR of 2nd molar and DMR of 1st molar

-DB cusp: Central fossa of 2nd molar


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B)Lingual Cusps:

They occlude into the lingual embrassures between their class counterpart and tooth mesial to it or into the lingual grooves of their counterparts

1)Ist Pre-molar: The lingual cusp does NOT occlude
with any opposing tooth.

2)IInd Pre-molar: Lingual embrassure btween Maxillary Pre-molars

3)Ist Molar:

-ML cusp: Lingual embrassure between 2nd PM and 1st molar

-DL cusp: Lingual groove of 1st molar

4)IInd molar:

-ML cusp: Lingual embrassur between 1st and 2nd molar

-DL cusp: Lingual groove of 2nd molar

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