MOB Amalgam Prep on 19

[Darya]

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Would someone please tell me what MOB is suppose to look like?
so, you cut the occlusal, then cut the mesial box and cut a box at the buccal pit? How deep do you make the buccal box?


Pre-clinical and have never cut one 😕

 

[DrAngie]

The depth is 0.5 mm into dentin (about 1.5-2 mm total depth). If you have a Sturdevant's "Art and Science of Operative Dentistry" textbook chapter 17 in the 5th edition talks about it.

 

[jackbauer!]

Would someone please tell me what MOB is suppose to look like?
so, you cut the occlusal, then cut the mesial box and cut a box at the buccal pit? How deep do you make the buccal box?


Pre-clinical and have never cut one 😕

deleted, imma ******

jb!😳

 

[rohlcall34]

Dr. Angie was right on. Get a Sturdevant's if you don't already have one. Best book ever. As far as what to call the prep. If it's just the buccal groove and/or pit it is a Class I. If you include the MOB, I believe it would be a modified class II. Have never done one in pre-clinic, but have done an OL on #3 which is called a modified class I. Kind of the same concept. Hope this helps.

 

[La Miraflorina]

Here are some clinical pics - don't know the exact depths

I'd assume you'd just add a M prox box since these pics show an OB, not an MOB.

 

[dddsmack]

.

 

[OffAngleHatchet]

Best bet is to ask your pre-clinical instructor, as different dental schools teach different techniques and have different specifications for what is considered ideal, and different rationales.

E.g., with DDDsmack's specifications for a class 2, I'd get hosed here at pacific.

 

[dddsmack]

.

 

[DrAngie]

I am interested in knowing what these other techniques are. The dimensions I was taught and what ddsmack posted are different by like 1/4mm but it still sounds like an ideal amalgam prep to me.

 

[crazy_sherm]

I am interested in knowing what these other techniques are. The dimensions I was taught and what ddsmack posted are different by like 1/4mm but it still sounds like an ideal amalgam prep to me.

Contrary to dddsnack's belief that UOP's deviation from normal prep designs is due to our superior clinical instruction, the real reason is because we're taught to the California board exam specs. For a molar class II amalgam, we use parallel walls, sharp line angles, 90 degree exit angles, pulpal and axial depth are 1.5mm, and proximal clearance is 0.5mm.

It wasn't until last year that California started taking WREB which has prep designs more commonly seen at most schools. A lot of the "ideal" preps you learn in pre-clin don't apply to real clinical situations, so the important thing is learning the rationale behind each aspect of the prep design and to apply those to the prep in clinic as opposed to memorizing numbers.

 

[DrAngie]

Contrary to dddsnack's belief that UOP's deviation from normal prep designs is due to our superior clinical instruction, the real reason is because we're taught to the California board exam specs. For a molar class II amalgam, we use parallel walls, sharp line angles, 90 degree exit angles, pulpal and axial depth are 1.5mm, and proximal clearance is 0.5mm.

It wasn't until last year that California started taking WREB which has prep designs more commonly seen at most schools. A lot of the "ideal" preps you learn in pre-clin don't apply to real clinical situations, so the important thing is learning the rationale behind each aspect of the prep design and to apply those to the prep in clinic as opposed to memorizing numbers.

Which goes without saying (referring to "ideal" preps in clinical situations and rationale)...And no, it's not about "memorizing" numbers, per se, however the OP is in fact a PRE-CLINICAL student that asked a question about cutting a prep on a plastic tooth...which would be an "ideal" prep with specific dimensions. We don't need to confuse the OP with "hypotheticals" and "well, in the clinics" right now. I don't know how it's done at other schools, but when I was in pre-clin my professor would have us to measure the dimensions with our instruments. Now, have I seen a lot of "ideal" situations in the clinic? Not really...but I do understand the rationale and what I need to do if (when) the prep is not ideal.

I thought that what I was taught about amalgam preps was pretty universal. It was made to sound as if the way it is done at UOP is waaay off then what ddsmack posted. As far as the CA "specs" everything sounds similar except for the line angles and the walls. So, what is the rationale behind having sharp axiopulpal line angles as opposed to having them rounded? Are the walls parallel to each other or parallel to the enamel rods?

 

[armorshell]

We actually put a .5mm bevel on the axiopulpal line angle to protect against amalgam fracture. Sharp angles and flat floors/walls everywhere else, occlusal prep walls are parallel to the long axis of the crown (Save a slight flare in the dovetail areas), proximal boxes are parallel to the long axis of the tooth/root. Ideal axial depth is 1 for pre-molars and 1.5 for molars. Width and height of the box is measure using gingival and proximal wall clearances between the adjacent tooth, .5mm being ideal for all three measurements (Gingival, buccal and lingual proximal wall clearances). 90 degree exit angles everywhere, and retention grooves just proximal to the axial wall (Assuming the depth is perfect)

 

[crazy_sherm]

Yes, the differences are minor, but it's easy to fail practicals in pre-clin over minor "mistakes". So if we were to do a prep the way it was mentioned earlier in the thread, we would fail here, but that in no way means there is something clinically wrong with it. Different schools and different faculty members will likely have different preferences, hence the advice earlier to double check with supervising faculty rather than take SDN's word for it.