Objectives of an Ideal Access Cavity Preparation in Root Canal treatment

Root Canal Treatment starts with a perfect Access Opening and the success of the Root Canal Treatment depends mainly on the shape and whether the Access opening is following the below mentioned objectives.
Access Cavity is the first step to a successful root canal treatment and the steps which follow are based on the accuracy and correctness of the access cavity which decides the path of entry and the line of access into the Pulp canals. So an appropriate Access cavity should follow certain objectives to achieve the desired result.

Objectives of an Ideal Access cavity preparation:

Straight Line Access: This is of atmost importance as it decides the path of entry of the files for BMP and the path of entry for the GP points for Obturation and this means that the steps following depend completely on the
Straight line access, so the objectives to be followed here are:

1. Improved instrument control
2. Improved Obturation
3. Decreased procedural errors
4. Removal of unsupported tooth structure (Dentin)

Conservation of Tooth structure: This objective is to ensures that the final restoration is strong enough to bear the occlusal forces and to support the Crown which will be placed on it after the procedure. So sufficient tooth structure should be left to prevent the treated tooth from breaking or fracturing.

1. Minimal weakening of the tooth
2. Prevents accidental fracture of the tooth

Unroof pulp chamber and expose pulpal horns: This is also an important step which will give you sufficient visibility and will let you to remove all the pulp tissue without leaving out any pulpal tissue behind after extripation and BMP. It also helps to locate any additional canals which might be present.

1. Maximize Visibility
2. Locate canals
3. Permit removal of pulpal remnants especially from the pulp horns
4. Permit straight line preparation

These are the objectives which should be fulfilled to make sure that the access opening which has been performed is a perfect one. Let us look at some points which should be followed to make sure that the Access opening will be useful in the success of next steps like BMP and Obturation.

Access should be provided in a straight line path to the apical foramen and not just to the canal orifice. This will help in cleaning and shaping completely as well as obturating the root canals easily. Any remaining Dentin should re removed which can form obstruction and it is called as Lip of Dentin, which has to be removed to get straight line access to to the apex of root canal.

The access opening should always be parallel to the tooth long axis.

The access opening should be done only on the Occlusal/incisal or the lingual surface of the tooth and tooth structure from the buccal aspect should not be removed unless necessary in case of Caries.

What are the consequences of a faulty or improper Access cavity preparation:

If the Access opening is too Small it can lead to:

Missing Canals

The walls of the cavity obstructing the free path of instrumentation of the root canal.

Pulpal tissue may be left behind in the coronal pulp chambers mainly in the Pulp Horns region. This will mainly lead to rapid discoloration of the tooth structure.

If the Access cavity prepared is too Large it can lead to:

Indiscriminate removal of tooth material will lead to weakening of the tooth structure

The remaining tooth structure will need extensive build up with the help of Post and Core if needed.

Achieving a Coronal Seal will become difficult leading to failure of the Root Canals therapy.

These are some of the simple objectives which should be followed during preparing an Access cavity for root Canal therapy. If these are followed it will in turn help in the easy and fast BMP and Obturation as well as play an important part in the success of the RCT performed.

The access cavity should be prepared keeping inn mind not only the BMP and Obturation aspects but also the need of proper sealing of the cavity to prevent seapage of Oral fluids into the root canal thus causing infection in the Treated Tooth.