What is the Mouth Gag? A Look at Different Types

Mouth Gags are surgical devices placed between the upper and the lower jaw to prevent the mouth from closing and gaining access to the oral cavity during throat and oral procedures. 
Despite a long history of usage, they are still found in every OR setting. 

The History of Mouth Gags

The earliest known medically used mouth gags date back to the late 1500s. In 1714 Lorenz Heister, a military surgeon, developed a screw-like device to open the patient’s mouth in trismus; a condition caused by tetanus in which jaw muscles become so tight that patients can’t open their mouth. The Heister gag became the prototype for future models, and in 1930, 250 years later, it could still be ordered with minor modifications. Primarily, it was the development of general anesthesia in 1846, however that resulted in an increased demand for jaw-opening devices. Anesthesia required unobstructed access to the endotracheal tube and a mouth gag allowed more access to the mouth whilst staying fixed in place during the procedure. 
Over time, based on the needs of surgeons, the characteristics of an ideal mouth gag were identified to guide future alterations to the design.

These characteristics can be summarized as: 

•    Provides adequate exposure to all parts of the oral cavity to perform surgery
•    Be compatible with different shapes and sizes of the oral cavity
•    Facilitates safe anesthesia administration via the endotracheal tube without kinking or putting pressure on it
•    Ensures secure fixation to prevent slippage and subsequent tissue trauma or damage

Based on these requirements, early tools were modified to allow the jaws to be "jacked" open and to hold an anesthetic tube securely in the tongue depressor. They were also designed in several parts for easier sterilization and more freedom of use.  
Eventually, they started to look like the mouthgags we are familiar with today. 
Since Heister’s design, a huge variety of mouth gags, with or without tongue depressors or plates, single- or double-sided, have been invented and distributed. 
Let’s take a look at some of the most common varieties of mouth gags that are still frequently used.  
 

Different Types of Mouth Gags

1.    Davis Gag

In 1910, a modification of the earlier Hartman gag caught the attention of anesthesiologist S. Griffith Davis, who modified it further for use in tonsillectomies. Henry Boyle eventually popularised the resultant variant, which led to the gag being better known as the Boyle or Boyle-Davis gag. It consists of a frame that joins a handle with a selection of tongue depressors called blades. The paddle of the depressor holds the patient’s tongue and lower jaw, while rubber-lined extensions at the top of the frame support the patient’s upper teeth. At least 20 further modifications of the Davis Gag were made from the 1920s through the 1990s.  However, the original design continues to be made by manufacturers and is still in common use among surgeons and medical practitioners. 
 

2.    Denhardt Mouth Gag

This instrument was first introduced in 1887 by Dr. Chalres Denhard as a modification of O’Dwyer’s gag, which was reported to be easily dislodged during surgery. To prevent this, the arms of the gag curve sharply at the point they exit the mouth. This design ensures that the handles are located close to the side of the face, so an assistant can easily keep the gag and the patient’s head stable. This improvement cemented the use of the Denhard gag for decades to come, and future modifications, such as the Denhart–Hoefert Mouth Gag, have only improved on what is already a reliable and time-tested instrument. 
 

3.    Jennings Mouth Gag

This gag was introduced in 1914 by St. Louis physician John Ellis Jennings. It is a modification of the earlier Whitehead gag. The built-in tongue depressor of the older gag was removed and simplified for easier adjustment. The Jennings Mouth Gag is operated via a single ratchet that can be controlled with one hand using the finger and thumb. Unlike earlier designs, which featured two spring-loaded ratchets, this variation has greatly increased the instrument’s ease of handling. The Jennings gag’s functional form and ease of use have kept it in production today. It is widely used. 
 

4.    Doyen-Jansen Mouth Gag With Grip Lock

The Doyen-Jensen is a variation on the Doyen Gag, an early design that simply held the mouth wide open but required stitching the tongue to maintain an airway and clear view for the surgeon. 
The Doyen-Jansen variety offers improved handling with its Grip-Lock mechanism that holds the blades in place at the desired width while conducting the procedure and allows a strong hold over the instruments. Its ratchet mechanism allows the mouth to remain open during the surgery, reducing tissue damage, and its curved front design allows for traumatic handling inside the mouth. 
These advantages, along with Doyen-Jansen’s enduring and functional design, mean it is still a regular part of many surgeons' toolkits. 
 

5.    Mcivor Gag

The Mcivor Gag is another early design designed by Robert J. McIvor in 1945. It was designed to protect patients' teeth against cracking or chipping that used to occur during sudden unconscious muscular contractions or convulsions under general anesthesia. It also improved on previous designs by reducing traumatization of the mouth tissue caused by the sharp edges and corners of previous devices. Compared to earlier variations, it was also designed to cause minimal obstruction to the view into the oral cavity or for the use of instruments. The all-around capabilities of the Mcivor gag mean it is still in service in operating rooms to this very day. 

Final Words!

As you can see, mouth gags have evolved a lot over the years. They have gone from simple retractors to keep the mouth open to multifunctional instruments that help medical practitioners during surgery and, at the same time, facilitate anesthesia administration. The fact that a huge number of modifications have been made and newer variants are still appearing today just proves that no single gag is perfect for all situations. If you’re interested in taking a closer look and comparing different types of mouth gags, explore our special category for the instrument here.