Monday 02.05.07

Oburation: Trying to completely fill the canal space.

The complete filling and closing of a cleaned and shaped canal. Use sealer and gutta percha.

What if we cleaned and shaped and left the canals empty? Bacteria and fluid will always seep back into the space. You can never remove all of the bacteria, so there will be recurrent decay.

Goal: to seal out fluid from entering the root canal system, and to seal in any irritants that can not be romeved from the root canal system.

Difficult because a bacteria is 1um. And the diameter of dentinal tubules is .5 – 3um. So there are going to be a lot of bacteria left in the tubules.

Goals:Uniform (without voids)Provide hydraulic pressure to move sealer into lateral canalsAvoid excess extrusion of sealerDon’t let gutta percha out the end.

Armamentarium… sealer, gutta percha, and instruments. That’s all! We will only be learning lateral condensation this year. Later we will learn some other techniques.

Ideal properties of materials:Minimally irritantNo shrinkageProvide a fluid-tight sealMoldableBacteriostaticEasily removed (some of the newer filling materials are harder and harder to get out, but if you missed something or made a mistake, and you can’t get it out, you’ve just condemned the tooth).Not stain tooth

Sealers:Kerr – ZOERoth – ZOE … we use this one.Tubliseal - ZOESealapex – Ca(OH)2Apexit – Ca(OH)2Ketac-Endo – glass ionomerAH26 – resinEndomethasone/N2 – Paraformaldehyde

ZOE is used most often and is zinc oxide eugenol. Paraformaldehyde is really bad for the patient. If it gets into the bone or the soft tissue it can cause some real damage.

Usually all the sealers come in a powder and liquid together.

Dimensional stability: All sealers tend to shrink until set. ZOE: sets within hours and they have long setting times.

AH26, ZOE and Ketac Endo provide relatively stable seals. Sealapex (Ca(OH)2) have fallen out of favor because it is prone to leakage.

Cytotoxcisity:All sealers are cytotoxic when fresh, but reduces on setting. Most sealers are sestorable when exposed to tissue and tissue fluids. ZOE is worse than most, but we use it because it goes down significantly, and it is absorbable by the body.

Antimicrobial Properties:Only the ZOE and Ca(OH)2 based sealers display significant antimicrobial properties. The others don’t have any. Most dental schools use ZOE sealers.

Adhesive:ZOE and Ca don’t adhire well. The others do.

Tips:Mix consistency – string an inch.Method of placement – lentulo, buttering master cone.Post op pain – extrusion, free eugenol.

All sealers tend to shrink, therefore it is necessary to minimize the amount in the canal by suing a central core of GP. So, the sealer is kind of like the glue holding the sealer in (even though the sealer doesn’t do that really).

Gutta percha:See ppt for percentages.

GP is less compressible than water – the only thing you can do is compact it to get rid of voids.

GP is rather cytotoxic, but by two weeks the inflammation is gone. This indicates that overall, GP is rather non toxic.

Types:

ISO (Standardized) – tip diameter corresponds to file tip diameters. Minimal taper. Used for master cones.Non standardized – they are lettered sizes. The tips are not measured… they are brought to a feather edge. Used for accessory cones.

Smear layer removal:A surface film of debris retained on dentin after instrumentation with files; consists of dentin particles, remnants of vital or necrotic pulp tissue, bacterial components, and retained irrigation. 17% EDTA irrigation for 1 minute will remove the smear layer. If you left it, the bacteria would effect the seal on the wall of the dentin. The lecture ppt has a nice photo of the smear layer v. the smear layer absent. If the dentin is over-etched, the dentin gets broken down.

Drying the canal:Paper points – they are tapered or numbered.Alcohol irrigation.

Obturation techniques: Lateral compactionChloroform dipWarm vertical compactionThermoplastic injection

We will deal only with lateral compaction:GP, D11 is a spreader, with lateral compaction, you are trying to squish the spreader alongside the GP.

Steps: Select the master cone (the first cone that goes in to length). Must match the apical prep.To make sure you’ve got it to the right tip diameter, you can use a “gutta gauge” to section off the excess end.Depth. Aim to reach 1-2mm from working length. Force. Be concerned about vertical root fracture.Quality of apical seal directly related to depth of spreader penetration, and the best seal is when spreader reaches to 1mm of working length. (results of a study: Allison DA, Weber CR, Walton R: JOE 1981)Goal: laterally smash the GP up against the wall. In the end, the whole mass of GP is “cold welded” together.

Plugger v. Spreader:Plugger is flat ended, spreader is tapered.

Q: when are you ready to obdurate?A: When master GP cone is of the correct apical diameter, reaches working length, has tug back (when you try to pull it out, there should be a bit of resistance – shows that the tip is well adapted to ensure that the GP cone will stay put) and no buckling, and THE

MOST IMPORTANT: that the spreader reaches to within 1-2mm of the working length with master gutta percha cone in place.

Problem solving:GP doesn’t go to lengthGP cone bucles at tipOnly a GP cone with a smaller apical diameter than the MAF will get to length.Lateral spreader doesn’t reach 1mm of WLBleeding during paper point drying