ACCESS CAVITY AND PRE-ENDODONTIC RECONSTRUCTION
- I-Introduction:
The term “preparation of the endodontic access cavity”, provided by the American school, allows visibility of the canal orifices and free access of the instruments to the apical foramen.
The access cavity includes architectural concepts which involve respecting the anatomical morphology specific to each tooth.
Certain clinical situations where there is significant coronal deterioration prevent us from ensuring a watertight operating field, hence the need for pre-endodontic reconstruction
- II-Pre-endodontic reconstruction
1-Objectives:
- Making it easier to lay the dam
- Create a real irrigation solution reservoir
- Facilitate the application of a waterproof dressing between sessions, avoiding any bacterial infiltration
- Obtaining reliable occlusal landmarks through reproducible placement of silicone stops of endodontic instruments
- Limit the risk of fracture of a severely damaged tooth by retraction of the residual walls.
ACCESS CAVITY AND PRE-ENDODONTIC RECONSTRUCTION
2-Problems:
A-Problem of the present coronal restorations:
Endodontic treatment is often indicated on teeth that have undergone direct or indirect coronal restoration. These restorations cannot be preserved and used as pre-endodontic reconstruction due to:
- Loss of sealing of the pre-existing restoration
- Presence of a carious recurrence
- Presence of coronal-radicular anchoring
- Difficulty in understanding endodontic anatomy
The restoration can be retained in the following cases:
- Recent restoration on a living tooth with symptoms
- On a tooth that contributes to the stability of a large span bridge
B-Periodontal problem:
In the absence of adequate sulcular space which prevents the achievement of an adequate pre-endodontic reconstruction and the establishment of a watertight surgical field, coronal elongation with or without osteoplasty is indicated.
3-Means and methods:
The choice of technique and material for the realization of the pre-endodontic restoration depends on:
- Ease of use and versatility in indications
- Fast setting time
- Sufficient resistance
- Ease of eviction at the end of endodontic treatment
a- Prosthetic reconstruction:
Preformed crown or cap:
- Indicated in case there is the presence of a crack
- Peripheral preparation of the tooth
- Crown sealing
- Size of access cavity
Temporary crown:
- Indicated in cases of moderate loss of substance
- Peripheral preparation of the tooth
- Fingerprinting
- Made in the Crown Laboratory
- Crown sealing
- Construction of the access cavity
b- Conservative reconstructions:
Matrixing:
- Indicated in cases of slight to moderate loss of substance
- Placement of the matrix + interdental wedge
- Placed at the bottom of the cavity and in contact with the exposed pulp horns of the Cavity to facilitate subsequent identification of the canals.
- Direct injection of a material (either composite or CVI)
- construction of the access cavity
Copper ring:
- Indicated for posterior teeth with severe decay
- Choosing the copper ring
- Cutting the ring using a crown chisel
- Adjusting it
- Sealing the ring with a CVI
- Construction of the access cavity
Orthodontic ring:
- Indicated for posterior teeth with severe decay
- it does not allow for sub-gingival and juxta-gingival reconstruction
NB : the removal of the carious lesion as well as the pre-endodontic reconstruction must be done without a dam in order to facilitate the clinical processes of bonding the composite or CVI.
- III-Operative field
1. Definition
- This is the first phase of canal preparation. It consists of creating an intracoronary access route of well-defined shape, dimensions and position which must allow:
- a direct passage to the orifice of the canals
- Easy and unconstrained penetration of the canal system in the apical direction.
- The quality of the access cavity determines the success of endodontic treatment
- Because its shortcomings will affect all subsequent stages of treatment.
2. Objectives
- Completely remove the contents of the pulp chamber: dentin debris, pulp and bacteria
- View all canal entries in a single incidence
- Allow instrument access into the canals without interference or coronal dentinal or enamel constraints
- Allow efficient irrigation of the canal system and constitute a reservoir for irrigation solutions (4-walled cavity)
- Provide a suitable base for any temporary coronary dressing
3. Instrumentation for creating the access cavity
- Diamond ball mill mounted on turbine for cutting enamel
- A transmetal cutter for cutting a metal crown
- A long neck ball end mill for trepanning the cavity
- A zekreya endo bur with a blunt tip that allows you to widen the endodontic cavity
- A DG 16 probe for channel location
- X-Gates drill for marking canal orifices
- Endodontic inserts for creating the access cavity.
ACCESS CAVITY AND PRE-ENDODONTIC RECONSTRUCTION
4. Operating protocol
- A. Creation of the delineation cavity: This is the first stage of the access cavity which consists of creating a cavity a few mm deep and which will be created with a ball mill mounted on a turbine.
- B. Penetration-trepanation: at a chosen point, specific to each type of tooth, trepanation is carried out using a long-necked round bur mounted on a contra-angle in order to preserve all tactile sensation.
- C. Elimination of the pulp ceiling: This is done using a long-necked ball bur with a diameter of 012 or 014 without spray, mounted on a blue ring contra-angle. The bur is placed under the roof of the cavity, and is used exclusively by setting back (never by pushing in order to avoid perforation). This step can also be done with a bur with a blunt tip (Endo Z)
- D. Cavity clearance:
An occlusal divergence of 2 to 3 degrees of the cavity walls
- E. Finishing the access cavity
5. Creation of access cavity tooth by tooth
1.Maxillary incisor-canine group
- Cavity drawing The access cavity is made on the palatal surface of the tooth. Its general shape is triangular; the apex of the triangle is located at the level of the upper part of the cingulum. The base of the triangle is parallel and at a distance from the incisal edge of the tooth.
- At the level of the canine, the access cavity takes on an elongated oval appearance in the vestubulo-lingual direction.
- Deepening the cavity; It is at this stage that the operator must orient the cavity towards the roof of the pulp chamber.
- Removal of the pulp ceiling and the palatal dentinal triangle
- The vestibular enamel-dentin triangle is removed with a round bur mounted on a turbine
- The lingual dentin triangle is removed with a long-necked round bur mounted on a contra-angle
2. Group of maxillary premolars
- Cavity drawing
- A straight line separating the occlusal table into two unequal parts, and the axis joining the two cusp summits. The vestibular and palatine canals are located on either side of this middle on the intercusp axis.
- The palatine canal is close to the central groove, and the vestibular canal is far from this groove.
- The ideal cavity is flattened, with a large vestibulo-palatine axis,
- Deepening of the cavity; the deepening of the occlusal cavity is done along the major axis of the crown. The cavity is deepened until a pulp horn is revealed. Finally, using a long-necked round bur used while working backwards, the remainder of the pulp ceiling is removed.
- Finishing
3.1st maxillary molar
- Cavity drawing
The cavity is trapezoidal, its design is guided by the contour shape of the tooth. It encompasses all the projections of the pulp horns on the occlusal surface. The cavity is located mesial to the occlusal surface, and generally does not exceed the enamel bridge.
- Identification of pulp horns
- The palatine pulp horn (P) is placed at: the intersection of the vestibular intercuspal groove and the main groove, slightly palatal.
- The mesiovestibular (MV) pulp horn is located immediately below the cusp tip of the same name.
- the disto-vestibular horn;
-Draw a straight line passing through the MV horn and parallel to the vestibular face of the tooth.
– Draw a straight line passing through the horn P and parallel to the mesial face.
– Draw a straight line joining the two pulp horns MV and P —> A triangle is drawn.
– Draw the height of the triangle perpendicular to the line (MV-P).
- The MV2; Extend the height of the triangle
described above mesially. The MV2 canal is located mesial to
the P-MV axis and in a triangle whose 3″ apex is on the height - Deepening of the cavity;
the cavity is deepened in the axis of the crown, Once the pulp break is obtained, the cavity is stripped
4. Second and third maxillary molars
The description of the access cavity of the 1st molar remains the same for the 2nd and 3rd maxillary molars. However, the anatomy varies, and the presence of the 4th canal statistically decreases significantly for the second and then the third maxillary molar.
On the other hand, the more distal the tooth, the more the distovestibular pulp horn tends to approach the axis connecting the MV canal and the P canal; the triangle therefore tends to flatten. It is not uncommon to note an alignment of the 3 canals on a second or third maxillary molar.
ACCESS CAVITY AND PRE-ENDODONTIC RECONSTRUCTION
5. Mandibular incisor-canine group
- Cavity drawing
The access cavity is made in the center of the lingual surface of the tooth. It has the shape of a triangle with a rounded apex located at the cingulum, and a base parallel to the incisal edge of the tooth, without ever approaching it. The general design of the cavity is guided by the contour shape of the tooth. In addition, the access cavity is more oval on the canine with a large vestibulo-lingual axis.
- Deepening the cavity
The cavity is deepened until the pulp is broken. The remainder of the ceiling is removed using the LN bur, working backwards.
The lingual triangle should be removed with an LN bur to facilitate access to the lingual canal
6. 1st mandibular premolar
- Cavity drawing
The pulp chamber being in the middle of the tooth, the oval access cavity is made at the expense of the vestibular cusp.
- Deepening the cavity
The deepening is done along the axis of the tooth. The cavity is enlarged until the pulp breaks through. The rest of the ceiling is removed using the long-necked bur working backwards, or using the Endo Z bur.
7. 2nd mandibular premolar
- Cavity drawing
The cavity, centered on the occlusal surface of the tooth, is oval, elongated in the vestibulolingual direction.
- Deepening the cavity
This step is not special and should be carried out as for the 1st PM. Before moving on to finishing, always check that the tooth does not have an additional canal.
8. 1st mandibular molar
- Cavity drawing
The cavity has a trapezoidal shape with a large mesial base respecting the mesial crest without ever exceeding the neutral zone.
- Channel tracking
The tooth has 3 vestibular and 2 lingual cusps; this implies that the vestibular and lingual intercuspal grooves are not opposite each other, the former being more mesial.
The area delimited by these two grooves is called the “neutral zone”. The distal pulp horn is located in this zone.
- The distal pulp horn is placed at the intersection of the axis materializing the middle of the tooth and the neutral zone
- The mesiolingual pulp horn (ML) is located close to the marginal fossa
- The MV horn is placed under the cusp tip of the same name.
- Deepening the cavity
- The deepening of the cavity should be done towards the ceiling of the pulp chamber .
- Once the pulp breach has been achieved, the residual tissues of the ceiling are removed using the long neck bur or an Endo Z bur,
- If there is a second distal canal, the cavity tends to become rectangular by elongation of the small distal base of the trapezium
- possibility of finding 3 mesial canals aligned on the same line
9. 2nd and 3rd mandibular molar
- The crown is smaller than that of the first molar and the occlusal table has four cusps. The landmarks are the same as for the first molar. However, the more distal the tooth, the more the mesial canals tend to move closer to each other, and sometimes even to fuse. When designing the ideal cavity, we will then tend to minimize the trapezoidal shape and make it more rectangular.
ACCESS CAVITY AND PRE-ENDODONTIC RECONSTRUCTION
Wisdom teeth can be painful if they are misplaced.
Composite fillings are aesthetic and durable.
Bleeding gums can be a sign of gingivitis.
Orthodontic treatments correct misaligned teeth.
Dental implants provide a permanent solution for missing teeth.
Scaling removes tartar and prevents gum disease.
Good dental hygiene starts with brushing twice a day.