Presentation on theme: "to shape the canals to the apical constriction of the canal space, regardless of the radiographic appearance of the actual tooth to shape the canals to."— Presentation transcript:
to shape the canals to the apical constriction of the canal space, regardless of the radiographic appearance of the actual tooth to shape the canals to the apical constriction of the canal space, regardless of the radiographic appearance of the actual tooth
Starting with the IAF, the root canal is enlarged to the working length through four file sizes.
A patency file is a small flexible instrument (08, 10) that will move passively through the terminus of a root canal without binding or enlarging the apical constricture. The aim is to prevent apical blockage, which will, in turn, reduce the incidence of ledge formation and transportation of the root canal. The use of a patency file also helps remove vital or necrotic pulpal remnants from the end of the canal. To use a patency technique, therefore, infers an intention to clean to the full canal length.
Glide Path (Canal Patency) Canal Shaping (Repeat until 25 to WL)
After the access preparation is made, the canal preparation is begun by assuring complete patency of the canal. This is done by inserting a size 15 Hedstrom file, employing one-eighth circle rotations and only light pressure. Next the root canal is enlarged coronally with a Gates-Glidden drill to the beginning of the canal's curvature using the step-back technique. It is important to coat the tip of the instruments with a lubricant (e. g. RC-Prep) in order to prevent binding within the canal.
Following enlargement of the coronal portion, the working length is determined radiographically with a size 15 K file in place. If the instrument tip falls more than 2 mm short, a second measurement radiograph is made after further careful instrumentation. If the root canal is too narrow to allow the K file to be inserted to the working length, passage to the apex must be carefully established with a Hedstrom file also. Only then can the size of the initial apical file be determined and the canal enlarged by four sizes.
Apical preparation is accomplished by alternating instruments-first a Hedstom file is used for circumferential filling and this is followed by a K file (noncutting tip) in a rotating working movement (balanced force technique). Following this, the canal is widened coronally with a size 20 Hedstrom file, and finally the entire root canal is instrumented to the working length with a prebent size 20 K file. If this file does not reach the working length, under no circumstances should any attempt be made to advance the instrument apically by rotating it.
A prebent K file prior to apical instrumentation. The instrument has become slightly straightened after being rotated apically.
Finally, the entire canal is smoothed by using the #35 AMF with balanced force rotations.
Filling the root canal with gutta-percha points and a sealer is the most biologically favorable and surest method in the long term
1.Nonirritating to the pulp tissue. 2.Tightly seal the canal both laterally and vertically. 3.Dimensionally stable so as not to shrink within the canal. 4.Should not support bacterial growth and should even be bacteriostatic. 5.Biologically compatible and nontoxic. 6.Easy to sterilize before use. 7.Radiopaque. 8.Should not discolor the tooth. 9.Should not harden too quickly and after hardening should exhibit good adhesion to both the dentin and the root canal filling. 10. Insoluble in tissue fluids and have a slight expansion.
– Easily manipulable with ample working time – Easily mixable in very fine powder particles and liquid form – Taky when mixed and adhesive to the canal walls – Biocompatible – Expansible while setting – Absolutely inert – Physically stable (unshrinkable after setting) – Non-resorbable – Insoluble in tissue fluids – Radiopaque – Not staining the tooth structure – Bacteriostatic – Easily removable with common solvents, if necessary – Non-immunogenic in the periapical tissues 8,10,152 – Neither mutagenic nor carcinogenic
Lateral Condensation of Gutta-percha
The cement is mixed and given the spatula test to determine the desired consistency. The apical half of the master point is coated with sealer and inserted into the canal to the predetermined depth.
A master point is selected that allows a friction fit in the apical portion of the root canal. When this is marked it is called 'tug back' (like pulling a dart out of a dart board). This may be difficult to achieve with small size gutta- percha points; therefore, it is usual to accept a friction fit in narrow canals. A point one size larger than the master apical file is usually selected.
If it is not possible to place the point to working length, select a point that passes to full length and trim 0.5 mm off the end using a scalpel (this has the effect of making the point slightly larger). Retry the point and adjust as necessary.
Mark the length of the point by nipping it with tweezers at the reference point and take a check radiograph with the cone in place.
Cut off the gutta-percha 1 mm below the cementoenamel junction or gingival level (whichever is the more apical) using a hot instrument and vertically condense the gutta- percha. This is important as remaining root-filling material may stain the tooth.