class 1

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ashly

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  1. Pre-Dental
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had to do this
 
I assume your class has taught you how to find adequate resources to answer the questions asked...
 
had to sorry
 
hello any1 can help me with finding info regarding class 1 cavity preparation and please dont tell me wikipedia
 
What specifically do you want to know?
 
Just google class I preparation, it will be easier than to wait for us to respond.
 
You should probably tell us what the material is as well, otherwise the responses you're going to get could potentially be wrongwrongwrong.
 
class I prep.. well it depends on the tooth that your are working on.... but best advice is get out the decay... also converging walls on buccal/lingual and diverging walls on mesial/distal if you are encroaching the marginal ridge
 
Ashly

Did the name G. V. Black come up in the information your instructor game you? If not you might want to start there.

Good Luck --- Your instructor sounds lazy and a jerk.
 
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UKdent said:
class I prep.. well it depends on the tooth that your are working on.... but best advice is get out the decay... also converging walls on buccal/lingual and diverging walls on mesial/distal if you are encroaching the marginal ridge
Click to expand...

Shouldn't B/L be parallel? No unsupported enamel...
 
WTF, where do you go to school. Don't you have faculty to help

1.5m depth in fissure
~2mm on L,B,M,D walls
Convergent L,B walls
Divergent M,D walls
90 degree cavosurface margin

Conserve 1.5mm of marginal ridge on premolars, 2mm on molars
Be conservative
pupal floor, rounded pupal/wall line angles
smooth walls

Use a 245 pear shaped bur or a 330
Sometimes I use a diamond to smooth everything out using the high speed but at about 1/4 speed.
 
At Pacific we do parallel B/L walls and divergent walls M/D when approaching the marginal ridge, which I'm told is how the WREB does it or some such.

pmantz uses a diamond for refining? In my mind smooth and diamond are opposites. :laugh:
 
Are you a D1? Look at Sturdevant. If you are a D3 and up, follow the caries.
 
At NYU it is MD 6 degrees obtuse relative to the pulpal floor and FL "slightly acute". Profs seem to be pushing the 1556 bur but upper classmen have recommended the 330 because it cuts less and has a 2mm working depth making it a bit easier to eye. Parallel walls FL are acceptable.
 
Aren't convergent B/L walls an essential element of the retentive form on a class I amalgam prep. I am sure parallel walls are acceptable, but are they the ideal?
 
pmantz said:
Aren't convergent B/L walls an essential element of the retentive form on a class I amalgam prep. I am sure parallel walls are acceptable, but are they the ideal?
Click to expand...

i agree..convergent is idea, parallel is acceptable.

jb!🙂
 
pmantz said:
WTF, where do you go to school. Don't you have faculty to help

1.5m depth in fissure
~2mm on L,B,M,D walls
Convergent L,B walls
Divergent M,D walls
90 degree cavosurface margin

Conserve 1.5mm of marginal ridge on premolars, 2mm on molars
Be conservative
pupal floor, rounded pupal/wall line angles
smooth walls

Use a 245 pear shaped bur or a 330
Sometimes I use a diamond to smooth everything out using the high speed but at about 1/4 speed.
Click to expand...


the person posting obviously came here for help and was not expecting ppl who are upperclassmen to be obnoxious brats. so just help and if your not going to do it in a nice way, dont do it at all!
 
mmasurf said:
the person posting obviously came here for help and was not expecting ppl who are upperclassmen to be obnoxious brats. so just help and if your not going to do it in a nice way, dont do it at all!
Click to expand...

I am a D1, and was merely surprised that a student was given a pre-clinical assignment without proper guidance thats all. I know I never had to go any farther then our simlab/text for instruction.
 
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pmantz said:
Aren't convergent B/L walls an essential element of the retentive form on a class I amalgam prep. I am sure parallel walls are acceptable, but are they the ideal?
Click to expand...
We were told a billion times to keep them parallel. So that's what we do.
 
Indeed, there are variations depending on the restorative material. You will want to mention this to impress your professor! With an amalgam restoration, your walls should ideally converge. With composite, parallel walls are acceptable and your preparation need not converge to the exactness of an ideal amalgam preparation. We are taught to use 330 or 329 carbides and diamonds work well for smoothing. Remember, the hatchet can be your friend! Good luck! On a side note, what school do you go to?
 
I believe the reasoning for parallel walls is not sacrificing good, supported enamel for retention when the depth of the prep is retentive enough. Additionally the undercuts you place with convergent walls could make the tooth more prone to fracture and encroach on the pulp horns. You'd be hard pressed to displace a class 1 out of a prep with parallel walls on more than one path: straight out occlusally, which isn't likely given the surface area of the prep and the fact that amalgam expands as it hardens.

I can't provide the research to support this, but hey, I'm a D1 and if I do convergent walls in simlab, I get an F for undercutting my prep. So I do what I do when I do what I do.
 
If you all can do perfect parallel walls i am impressed, i find it myself nearly impossible. Just out of curiosity what bur do you use? I guess if you can get them perfectly parallel then that would work, but on a shallow prep i would make sure they aren't diverging in the least little way.

Also according to the anatomy of a tooth the angulations of the triangular ridge makes the enamel rods slightly tilted.... so diverging walls would leave no unsupported enamel it would in fact follow the enamel rods. (When I say diverging I am talking about only a few degrees, i use the 330 and the shape of the bur provides adequate divergance)
 
UKdent said:
If you all can do perfect parallel walls i am impressed, i find it myself nearly impossible. Just out of curiosity what bur do you use? I guess if you can get them perfectly parallel then that would work, but on a shallow prep i would make sure they aren't diverging in the least little way.

Also according to the anatomy of a tooth the angulations of the triangular ridge makes the enamel rods slightly tilted.... so diverging walls would leave no unsupported enamel it would in fact follow the enamel rods. (When I say diverging I am talking about only a few degrees, i use the 330 and the shape of the bur provides adequate divergance)
Click to expand...

I'm sure our walls aren't perfectly parallel, but it's not hard to get very close to that goal, probably equally as hard as getting a perfect 6 degree converging taper.

We definitely still do the diverging taper at the marginal ridges to follow the enamel rods though, despite the parallel B/L walls.

As far as burs, I do my initial outline and depth cuts with a 330 then switch to a straight-fissure bur like a 55 or 56, depending on the size of the prep, to refine my walls to parallel. Then I drop the pulpal floor the last few tenths and refine the prep in general. I do everything with a high speed.
 
as far as the burs as such go...i personally like to start w/ the 330 and use that for as long as I can...both for depth and for B/L convergence...however that leaves the M/D walls convergent as well...at which point I decide to go for a straight bur and just angle it myself..or something conical and let the bur do the work...depends on my mood.
 
armorshell said:
I'm sure our walls aren't perfectly parallel, but it's not hard to get very close to that goal, probably equally as hard as getting a perfect 6 degree converging taper.

We definitely still do the diverging taper at the marginal ridges to follow the enamel rods though, despite the parallel B/L walls.

As far as burs, I do my initial outline and depth cuts with a 330 then switch to a straight-fissure bur like a 55 or 56, depending on the size of the prep, to refine my walls to parallel. Then I drop the pulpal floor the last few tenths and refine the prep in general. I do everything with a high speed.
Click to expand...

OooooOOOoo ahhhhhhhhhh. 😉

jb!🙂
 
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Streetwolf said:
We were told a billion times to keep them parallel. So that's what we do.
Click to expand...

We use the CRDTS board exam criteria for our praticals and self evaluation in our operative lab. I am about 100% sure that convergent B/L walls are the ideal for this exam. I can see if you keep the axis of you bur perpendicular, the tapered angle of the bur will produce convergence necessary for retention.

I find it interesting the discrepancies between schools in what I was taught/read is an essential part of the retentive form of an amalgam prep.
 
pmantz said:
I am a D1, and was merely surprised that a student was given a pre-clinical assignment without proper guidance thats all. I know I never had to go any farther then our simlab/text for instruction.
Click to expand...

Did it ever occur to you folks that this is probably NOT a dental student looking for answers to a question you all seem to know all about, but aren't willing to give a little help. They are on SDN as a "Pre-dent" so they could very well be doing a 5th grade science paper for all we know.....

Here is how a textbook from dental school explains it:

Class I lesions occur in pits and fissures of all teeth, but this class is essentially intended for bicuspids and molars. Figures 2-14 and 2-15 illustrate common sites on the teeth where this lesion might occur.
(Baum, Lloyd. Textbook of Operative Dentistry, 3rd Edition. W.B. Saunders Company, 1995. 2.6.1).

Sequence of Preparation.

It is assumed that the dento-enamel junction has been penetrated but that no substantial amount of dentin has been destroyed by caries. If caries penetration has been deep, attention is directed to optional step 4 following.

1. Enter the pit with a No. ½ round bur to a depth of 2 mm (1½ mm for small premolars; 3 mm for husky molars). *

2. Maintaining this depth, the cavity is extended out all grooves until evidence of defective fissures disappears. This includes supplemental as well as developmental grooves (Fig. 11-10). Proper depth of penetration is automatic with an experienced clinician; not so with a novice. Until such time as he is able to measure relative cavity depth with the naked eye, a measuring "tool" is indicated. This can be done by scoring the shank of a bur with a diamond disk and/or by painting the shank of the bur with a marking pen 2 or 3 mm from the end (Fig. 11-11). In use this can serve as a depth gauge, as this small pilot bur mortises a guide groove for the cavity preparation. As mentioned earlier, this initial guide groove or slot is prepared with one major thought in mind—the elimination of potentially carious enamel fissures.

3. Use of the No. 330 bur is standard for this preparation, although many clinicians also utilize other burs as well (Fig. 11-12). Endeavor to restrict the width of an isthmus so that this pear-shaped bur cannot be withdrawn occlusally from the depth of the preparation because of the narrowed opening.

Variations in Class I outline and design for maxillary molars were shown in Figure 11-8. Similarly the variations in outline for the lower molars are found in Figure 11-13.

Because of their smaller size the premolars often fall prey to overcutting and overextension from the careless use of a bur. The proper outline for Class I cavities of maxillary premolars is shown in Figures 11-14 and 11-15, mandibular premolars in Figure 11-16. Another common error often made by the operator is to tilt the head of the handpiece toward the facial, presumably to obtain better vision. This makes a groove that is not properly aligned with the occlusal surface (see Figs. 11-14 and 11-16).

4. (Optional step) Pulpal floors may now be rendered flat with a No. 35 or 37 slow-speed inverted cone bur. Axial walls on lingual grooves of upper molars and facial grooves on lower molars may be treated likewise (see Fig. 11-8F). Care should be taken not to unduly undermine the walls during this stage of the preparation.

5. If caries has extended below the optimal level of floor depth, the removal of carious dentin is postponed until the cavity has been essentially prepared. Carious dentin is then removed with an excavator or round bur.

6. When a cement base is placed to raise the pulpal floor to its proper height, it may be finished with a No. 35 or 37 bur so that it will be smooth and flush with the adjacent dentin (Fig. 11-17).

7. Final finishing of the enamel margins is accomplished with hand instruments (Figs. 11-13 and 11-18) and with high-speed burs (Nos. 330 and 245) under light pressure.
(Baum, Lloyd. Textbook of Operative Dentistry, 3rd Edition. W.B. Saunders Company, 1995. 11.3.1.2).
<vbk:0-7216-3484-2#outline(11.3.1.2)>



Hope this helps a little.
 
pmantz said:
We use the CRDTS board exam criteria for our praticals and self evaluation in our operative lab. I am about 100% sure that convergent B/L walls are the ideal for this exam. I can see if you keep the axis of you bur perpendicular, the tapered angle of the bur will produce convergence necessary for retention.

I find it interesting the discrepancies between schools in what I was taught/read is an essential part of the retentive form of an amalgam prep.
Click to expand...

i wonder if different regional exams have differing opinions on what makes a prep "ideal." ? just a thought..

jb!🙂
 
They certainly seem to, considering we're being taught to the WREB at Pacific doing parallel walls and all you 'old school' northeasterners are kicking around with "an endodontist's best friend" converging preps. 😉
 
armorshell said:
They certainly seem to, considering we're being taught to the WREB at Pacific doing parallel walls and all you 'old school' northeasterners are kicking around with "an endodontist's best friend" converging preps. 😉
Click to expand...

i am not sure about this whole parrallel vs convergent business on the wreb. we at vcu are taught since day one that convergent is ideal, and we seem to do just fine on the wrebs here so go figure unless they teach me something totally different 4th year b4 the exam which i doubt we go with convergent walls.
 
rocknightmare said:
i am not sure about this whole parrallel vs convergent business on the wreb. we at vcu are taught since day one that convergent is ideal, and we seem to do just fine on the wrebs here so go figure unless they teach me something totally different 4th year b4 the exam which i doubt we go with convergent walls.
Click to expand...

I'm just telling you what they tell me and I'll do what they tell me to until I graduate and then figure out what's best for my patients and me on my own. Anecdotally, I haven't heard of any problems down in the clinic with amalgams exploding out of peoples mouths. Anyone else from the parallel camp care to weigh in here?
 
Like armorshell, I'm at Pacific. Yes, we do parallel walls (which means we do perpendicular to the occlusal plane). At least that's what's considered ideal. Slightly undercut or slightly overcut is acceptable (hey we're not perfect), but deliberately undercutting by something like 6 degrees is failure at our school.

We learned from our classes that the enamel rods are coming out perpendicular to the outer surface of the tooth. Thus areas where the tooth is either undercut or has an angle of exit less than 90 degrees (like in class II preps) leave enamel rods that are unsupported, and can potentially fracture. Bad news.

So all the amalgam preps we do here at Pacific are 90 degrees, parallel walls (with a little "flare," or "diverging walls" as everyone here is calling it, on marginal ridges). The diverging walls are to give the marginal ridges extra support, so they don't fracture.

We learn that a 1.5mm pulpal depth, with retentional grooves near the DEJ, are enough for amalgam retention. So the argument of undercuts being needed for retention doesn't really click with me.

Our school is known for getting their students to do well on the Boards, so I'm sure we do what we do for a good reason. It would definitely be good to see the research to back it all up though, seeing as we're moving towards evidence-based dentistry. 😀

That's a good point armorshell about reaching pulp horns. I forgot about that. 👍
 
Oops my bad...

Class I's don't have retention grooves. I guess I got a bit carried away with Class II's. 😛
 
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Pacific here.
I never thought such a primitive thread topic would spur such an interesting discussion.
Well, in a different life, I was taught that amalgam preps HAD TO have convergent walls, or they failed us. Now they tell me they need to be parallel ... make up your mind already ! What was frustrating to me was that none of my faculty could really give me solid reasons as to why parallel walls were better (or not) that convergent ones, so now I'm forced to come up with my own:

-Parallel walls conserve tooth structure at the base of your prep (remember, the isthmus width will always be the same).
-Dentin has a modulus of elasticity (which is actually surprising). If you condense your amalgam sufficiently, the friction resistance generated by the dentin hugging the amalgam once set (in addition to amalgam hygroscopic setting expansion mentioned earlier by armorshell), is really enough to retain your restoration, rather than having to mechanically lock it in place.

It all boils down to different schools of thought. They all work just fine.
 
First time ive used this but here it goes.....



:beat::beat::beat::beat::beat::beat::beat:
 
just do whatever your professor tells you to do. obviously, from what is seen in this thread, each school does even a simple procedure like a Class I amalgam prep a little bit differently. We were taught to use 256 burs from day 1 (which isn't the case in a lot of schools) and we were taught to prepare parallel walls B/L, which isn't the case in some schools. follow the procedure as instructed, ask your preclinical faculty for help since whatever they teach you in class is going to be the basis for grading on your practical. parallel walls buccolingually eliminates the possibility of leaving unsupported enamel while provides good enough of a retention if it's done correctly. convergent B/L walls do provide higher retention, but leaves for possibility of unsupported enamel which is something you don't want to do.
 
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