Steps of Cavity Preparation: Types and When to Use Them

If you're wondering what cavity preparation is, it's the process of removing decayed or damaged parts of a tooth to restore its function and appearance.

There are different types of cavity preparations that dentists use depending on the severity and location of the decay.

In this post, we'll be diving into the various types of cavity preparations and when they should be used.

Whether you're a dental professional or simply curious about dental procedures, this article is for you!

So let's jump right in and explore everything there is to know about these important dental techniques.

What Are Cavity Preparations?

If you have a cavity, your dentist will need to drill a hole in your tooth to remove the rotted substance and repair your tooth with a filling. This is referred to as cavity preparation. 

A preparation may also be required if the surface of your tooth has a fracture, abrasion, or erosion.

Your dentist will examine your teeth and take X-rays to identify the minor design elements required to ensure the longevity of your filling. 

These design elements include the form and size of the entrance into your tooth, which allows the dentist to remove the decayed substance, as well as design elements that keep the filling from moving or fracturing. There may be situations when the dentist must remove a tooth.

What Are The Principles Of Cavity Preparation?

Cavity preparation is a four-step process aimed at removing damaged tooth tissue and creating a stable foundation for restoration. 

The procedure generally follows these steps:

1. Opening the Cavity
   The dentist removes any faulty restorations or opens the cavity to access the affected area.

2. Removing Diseased Dentin
   This step involves clearing away decayed dentin to stop the spread of disease and prepare the tooth for treatment.

3. Evaluating and Shaping the Tooth
   After removing the decay, the dentist assesses the remaining tissue, removing any unsupported enamel and ensuring the tooth is stable.

4. Finishing the Cavity Margins
   The edges of the cavity are smoothed and shaped to support the restorative material.

Minimally Invasive Approach

The extent of cavity preparation is based on clinical and radiographic evaluations of the caries lesion. Dentists today focus on minimal invasiveness, using modern materials and techniques that preserve as much healthy tooth structure as possible.

Key Steps in Cavity Preparation:

1. Removing Carious Tissue
   The dentist ensures the removal of decayed tissue while creating space for the restorative material. The focus is on preserving healthy enamel and dentin.

2. Groove Analysis
   The tooth surface must be clean and clearly visible. Magnification tools, like prismatic lenses or microscopy, are often used to ensure an accurate diagnosis. This helps determine whether to seal, restore, or perform a more complex treatment based on the condition of the grooves.

3. Sealing
   Sealing is a preventive measure to protect deep grooves from caries. It reduces the risk of cavities by up to 51%. However, care must be taken not to seal over active caries, as this could mask the issue.

4. Providing Adequate Space for Restoration
   The cavity is shaped to ensure there’s enough room for the filling or crown, creating a structure that will securely hold the restoration in place.

By adhering to these principles, dentists ensure effective cavity preparation, successful restorations, and long-term oral health for the patient.

Cavity Preparations Steps

1. Class I – This is the most common type of cavity preparation and is used when decay is found on the biting surfaces of the back teeth (molars). The tooth will be trimmed down so that a filling can be placed.

2. Class II – A class II cavity preparation is necessary when decay is found on the chewing surface of the premolars or molars, or on the inside surfaces of the front teeth (incisors and canines). The tooth will be trimmed down so that a filling can be placed.

3. Class III – A class III cavity preparation is necessary when decay is found on the inside surfaces of the molars (between the cheek and tongue). The tooth will be trimmed down so that a filling can be placed.

4. Class IV – A class IV cavity preparation is necessary when decay is found on the biting surfaces of the incisors or canines, or on the inside surfaces of the incisors (between the gum and cheek). The tooth will be trimmed down so that a filling can be placed.

Class 1: Enameloplasty

Enameloplasty is also referred to as "Selective grinding," "Spot grinding," "Occulusal reshaping," and "Odontoplasty." It is a non-invasive (non-surgical) aesthetic dentistry treatment that involves altering the tooth structure.

Enameloplasty alters the occlusal surface of the tooth to treat problems such as supra erupted teeth, or teeth that erupt longer than the other tooth, causing interruptions in closing the mouth as well as aesthetic concerns. 

Enameloplasty has a limited amount of tooth structural repair. At the same time, the natural tooth form and contour are preserved.

Class 2: Partial Removal of Cavity Wall

The cavity wall is the visible outermost layer of the tooth above the gums. It is also the stratum most vulnerable to deterioration and cavities. A frequent method of cavity preparation involves partial removal of the cavity wall.

This entails removing both the diseased or decayed section of the tooth and a small margin of healthy tooth around the cavity. This sort of preparation is frequently utilised for tiny, shallow holes.

Class 3: Complete Removal of Wall

When a tooth has been extensively injured, there is extensive decay, or the tooth has undergone root canal therapy, the wall must be completely removed. Extraction is another term for this type of cavity preparation.

Class 4: Partial Removal of Floor and Wall

When preparing a tooth for a Class 4 cavity, your dentist will remove some of the tooth's structure. This comprises the enamel, dentin, and any deterioration that has entered the pulp.

The purpose is to create a clean, flat surface on which to lay the filler material. In some circumstances, your dentist may need to remove a portion of the surrounding bone to expose the decay.

Class 5: Complete Removal of Floor and Wall

This is the most aggressive type of cavity preparation and is utilized when there is a substantial amount of decay or when the decay has reached the pulp of the tooth.

This method of cavity preparation entails removing the whole floor of the tooth down to the gum line.

Class 6: Preparation for Restoration with Filling Materials

Class 6 cavities are the most difficult to restore and require the use of filling materials. The first step is to remove all decay and damaged tooth structures.

The next step is to prepare the cavity for restoration by shaping it and adding retention features if necessary.

The cavity is filled with a material that will restore it to its original shape and function.

Indications for Different Types of Cavity

There are different types of cavity preparations, and each has its own indications. 

Here are some examples:

1. Class I is a term that refers to tooth decay that happens on visible tooth surfaces to your dentist. Cavities on the chewing surfaces of your back teeth, such as your molars and premolars, fall into this group, as does decay on the front or back surfaces of your front teeth.
2. Class II Cavities are not visible to the naked eye and occur on the surfaces between the molars and premolars.
3. Class III decay occurs on the surfaces between the front teeth but does not impact the tooth's cutting edges. This degradation categorization, like Class II, is not apparent.
4. Class IV decay occurs on the surfaces between the front teeth, but it also affects the teeth's cutting edges.
5. Class V Cavities arise along the gumline on the front or back of either front or back teeth.
6. Class VI decay appears on the upper surfaces of the teeth, such as the incisal margins of front teeth or the cusp tips of back teeth.
   

When you visit your nearest dentist for a check-up, they will use devices to locate noticeable soft spots on your teeth. 

To diagnose cavities, your dentist may also require current X-rays (or take fresh X-rays).