April 03, 2021
A patient visiting a dental clinic with the primary complain of missing tooth or teeth knows that he or she is going with the hope of getting new teeth (artificial) by means of prosthesis. Dental prosthesis can be removable or fixed. They can be in the form of dentures, crowns, bridges, etc. However, the challenge for the dentist is to fabricate the prosthesis such that the functional harmony of the oral cavity is maintained. This means that the final prosthesis should not interfere with speech, chewing or overall aesthetics of the patient.
In the process of fabricating a prosthesis, the dentist needs to first prepare certain teeth who are sturdy enough to receive the prosthesis. Preparation of teeth means trimming the teeth in certain dimensions from all surfaces. One of the most important steps is the depth till which the tooth or teeth must be prepared. This involves the need of the tooth or teeth to be prepared subgingival (below the gums) too. It ensures that the prosthesis will properly brace the margins of the teeth.
Following the preparation of teeth, an impression is taken which replicates the alignment of the teeth in arch. But this impression might not capture all the minute details like the subgingival preparation. In order to get this, before taking the impression, the gingiva is made to retract. The process of gingival retraction conventionally has been done by cords, that are placed in the subgingival area. This procedure can however be painful for the patient and hemorrhage from the gingival area can hamper the quality of impression. It is extremely essential to ensure that the subgingival area is dry before taking the impression. Conventional cords are dipped in vasoconstrictors or astringents that restrict the amount of hemorrhage. However, these are relatively less effective and take a long time in achieving complete stoppage of blood flow. In order to overcome these challenges posed by conventional retraction cords, astringent gingival retraction pastes were developed.
Astringent Gingival Retraction Pastes come in the form of dispensing pastes that have a thin soft edge capsule tip through which the paste oozes out. The tip is placed inside the subgingival region and the paste is made to flow around the tooth or teeth such that it fills up the subgingival region. The tip also has a ring drawn outside which helps the clinician in determining how deep he or she has placed the tip. The placement of the tip is not at all painful for the patient in comparison to retraction cords. In fact, the gingiva is effectively retracted too.
The astringent paste is left in the mouth for at least 2 minutes. After that, the air-water combination spray helps the dentist remove the paste. One advantage of the astringent paste is that the presence of 15% aluminum chloride helps in reducing the hemorrhage from the gingival tissues to a great extent. Once the paste is removed, the impression is taken and the clinician can appreciate the subgingival areas on the impression.
The retraction of gingiva at times is also needed in restorative procedures. These restorations are such that the decay on the tooth covers at least two surfaces or only one surface that corresponds to the cheeks. Gingival retraction paste is helpful in these cases as not only do they control the hemorrhage but also the amount of moisture that the tooth should be free from. Moisture control in restoration procedures is key as during the placement of a cement or a crown, the moisture hinders the composition of the cement, due to which it does not completely adhere to the structure of the tooth or teeth. In modern times, impression taking has also become a digital process in developed countries. Gingival retraction pastes can be used and are suitable with these digital impressions as well.
It is important to remember that these pastes cannot be used in teeth whose surrounding bone health is poor or if there is a lesion associated with the roots of the teeth. Application of the paste in these teeth can cause severe irritation and pain to the patient.
Astringent Gingival Retraction Pastes are a great development in the field of dentistry as patients can now receive prosthesis that adhere to the teeth with a snap fit without harming the underlying bone and the surrounding gingiva. Despite the fact that it is an expensive alternative to the conventional retraction cords, the ease of application of the paste system is the greatest advantage for both the patient and the dentist.