subgingival floss

What is subgingival floss?

Subgingival floss is a type of dental floss used to pull back the gums. Typically, when a dentist trims a tooth to attach a crown, they place a piece of floss called a retraction cord or gingival retraction cord between the tooth and the gum. A subgingival floss or retraction cord is a special tool in dentistry that is usually used to prepare teeth for restorations such as all-ceramic crowns and dental laminates. When dentists prepare teeth for fixed restorations such as crowns, bridges, or even veneers, they must remove a portion of tooth tissue. In this process, subgingival floss is gently worked under the gumline, sulcus, and around the tooth to prepare for the crown, bridge, laminate, and other dental restorations.

A sulcus is the small groove between a tooth and its surrounding gum; plaque usually collects in this area, causing a number of problems for the health of the gums and teeth. To achieve low-impact gingival displacement, subgingival flossing is the most reliable and safe tool for controlling impression-induced gingival recession. One study suggests that a minimum gap width of 0.20 mm is required for consistent accuracy and flawless impression taking, and the minimum time in the groove to achieve this dimension is 4 minutes. Several guidelines exist for predicting post-restoration gingival margin levels and periodontal health after preparation, gingival retraction, and impression removal. These guidelines should be considered at the diagnostic stage and prior to the restorative appointment as they can provide the patient with a stable and healthy periodontium after preparation, impression, and restoration placement. Measurements in the facial and interproximal areas of the unprepared tooth can provide a predictable classification. These bony crown positions can be divided into three categories: normal, low, and high:

• For a normal crown position, these two measurements for anterior teeth should be approximately 3 mm facially and 4 mm interproximal if adjacent teeth are present, and this relationship occurs in approximately 85% of patients.
• When the depth of the bony crown to the gingival margin is greater than these measurements, it is considered to be a low bony crown, which occurs in approximately 13% of patients.
• If the depths are less than these measurements, it is considered a high crown position, which occurs in 2% of patients.

In a normal bony crown position, the gingival complex returns to a natural crown relationship after tissue manipulation and impression taking. However, in a high crown relationship, impaction manipulation and placement of preparation margins below the gingiva place the definitive restoration too close to the bony crown, causing a breach in biological width. The lower crown position with a thin biotype is considered the most unstable clinical situation and can cause the greatest variability in the final gingival position. For optimal restorative results, the lower and upper bony crown positions should be identified at the diagnostic stage and corrected before restorative treatment through osseointegration or orthodontics. Therefore, during gingival repositioning, the size and number of subgingival floss should be modified according to the bony crown position and tissue biotype. The use of a single-thread technique in upper and lower crown positions and a double-thread technique in conventional crown positions is recommended.

In prosthodontics, subgingival floss is the most common method used to move tissue for impression taking, and a variety of types of floss and chemical solutions are available. Most flosses are made from various fabric combinations, including wool, silk, cotton, and synthetic fibers, which are twisted or braided together. The flosses can also be distinguished as soft or compact. Soft filaments are easy to position and have a high capacity to absorb gingival fluids or chemical solutions, but they can easily break during placement and removal and disintegrate upon contact with collection fluids. Compact subgingival filaments offer better horizontal movement, show minimal degeneration from retraction fluids, and are less prone to breakage, but are difficult to place and absorb minimal gingival fluids or retraction.

Types of subgingival floss

Working on the gums is very sensitive due to its texture, and therefore the dentist must be very careful when working so that no mistakes are made and as a result, effective treatment is provided. The use of subgingival floss and its type is very important, as one of the tools that directly deals with the patient’s gums and on the other hand sometimes causes irritation, inflammation and even bleeding of the gums. The following is an introduction to the types of subgingival floss:

• Twisted cords: This type of floss is the oldest type used in dentistry. They are made up of two or three threads twisted together. Twisted cords are easily inserted and larger threads can be separated into two smaller cords. However, the threads are easily separated during placement and can get tangled in the rotating bur during preparation.
• Braided cords: Braided cords are woven so tightly that it is impossible to separate the threads. These cords are very stable, remain intact during placement, do not tangle or tear with rotating diamond burs, and come in two types: solid core and hollow core. Solid core cords have more bulk and horizontal shrinkage, but are stiffer and more difficult to place. Hollow core cords are more flexible and easier to place, but have less bulk and less horizontal shrinkage. Some braided subgingival cords contain aluminum sulfate and also have the property of coagulant and contractile properties of gum tissues. Another type of subgingival suture (Sil-Trax Plus) contains zinc phenol sulfonate as well as epinephrine hydrochloride, which is for rapid blood coagulation and is free of complications and is available in 4 thicknesses of 00, 0, 1, and 2. On the other hand, the Sil-Trax Epi model is impregnated with epinephrine hydrochloride and is excellent for tissue contraction as well as blood coagulation and is available in 4 thicknesses of 00, 0, 1, and 2.
• Knitted cords: This type of subgingival suture is knitted without a central thread. They are easily compressed, do not break, hold chemical solutions 2.5 times longer than other types of cords, and do not knot during preparation in rotating diamond burs. However, they are easily cut during preparation and provide less gingival contraction because they are easier to compress. This type of subgingival floss is free of additives and has the ability to absorb epinephrine and other coagulants. It has 6 different thicknesses: 000, 00, 0, 1, 2, 3.

Benefits of using subgingival floss

Subgingival floss can be used to completely place the edges of the teeth that have been trimmed and are located around and under the gums into the mold.
Types of subgingival floss can prevent bleeding gums during work due to the presence of a hemodent solution and anticoagulants.
Subgingival floss prevents blood from entering the mold and also allows the trimming of laminates or any type of veneer trimming performed by the dentist to fit the trimming line more accurately and better into the mold, and as a result, the laboratory can make the best working model and deliver it to the dentist.
Another important use of subgingival floss is to increase the absorption of chemicals.
Subgingival floss helps the dentist move the gum away from the tooth a little and perform the desired work with better and more precise details.
Subgingival floss can be used during impression taking to prepare a crown or dental prosthesis to push the gums aside.
Types of subgingival floss that contain hemodent are used to coagulate the blood under the gum, which in addition to causing a bulge in the gum, creates a more suitable impression for the impression.
When the dentist decides to attach the crown, he must first trim the tooth to the desired size and then begin placing the crown. To do this, he uses subgingival floss so that he can easily continue the work.