Prolonged near maximal mouth opening has been shown to result in TMJ arthralgia, open lock jaw, trismus, and/or myalgia of the masseter for up to 14 days due to activation and prolonged sensitization of nociceptive neurons in the trigeminal ganglion and nucleus. In addition, there are also the sphenomandibular and stylomandibular accessory ligaments that serve, to some degree, as passive restraints on mandibular motion. The superior retrodiscal lamina consists of elastic fibers that attach to the tympanic plate and function as a restraint to disk movement in extreme translatory movements. Dislocation of the mandible with maximal opening is prevented by the temporomandibular ligament while anterior dislodgement of the articular disk is prevented by the superior retrodiscal lamina. Dislocation or derangement of the articular disk and mandible is prevented by the functional ligaments surrounding the joint: the collateral (discal), capsular and temporomandibular ligament.

After this point, further opening must occur via an arthrodial (sliding) mechanism within the superior compartment, usually up to 40 to 50 mm. The inferior compartment permits a ginglymus (hinging) motion that results in mouth opening up to 20 mm.

The TMJ is a compound, diarthrodial joint that is divided into a superior and inferior compartment by the articular disk. Mouth opening is facilitated by the muscles of mastication and the TMJ. We also explore the disadvantages and risks of their use, especially those that clinicians should be aware of for patient and operator safety. This article highlights the most frequently used well-designed mouth gags and the applications for which they provide the most benefit. Furthermore, mouth gags are safe and protective for the patient and operator while having the desired maximal incisal opening that allows for better exposure and visualization of the operative field for the procedure. From the operator’s perspective, the mouth gag enables efficient completion of time and technique-sensitive procedures that rely on patients keeping their mouth open consistently. Mouth gags have the added benefit of decreasing the incidence of perioperative and postoperative TMJ pain, dysfunction, and muscle stiffness during lengthy procedures.

Mouth gag with ratchet and pinion adjustment and ebony handleīlack’s gag with sheet spring and a ring type retention system To date, there are more than 36 subtypes of mouth gags ( Table 1 ) that provide a wide variation in design and modification of function for providing transoral access for examination, surgical intervention, and general dental care. In use since 1220 AD, mouth gags can be defined as instruments with levers that are used to separate the maxillary and mandibular arch and maintain the mouth in an open position. Mouth gags are fundamental in a provider’s armamentarium as a solution to this spatial dilemma. Compounded with behavioral challenges, such as those encountered in the pediatric or developmentally delayed population, and physiologic or structural limitations such as tetanus or temporomandibular joint (TMJ) disorders, access can be quite frustrating. With maximum opening of the oral cavity limited to 40 to 50 mm, access and visibility for manipulation of intraoral and pharyngeal structures tends to be insufficient. The reader should be able to understand the benefits and limitations of the popular mouth gags in use today. This article should help the reader to select the appropriate mouth gag based on the setting, surgical procedure and needs of the operator. This review should enable readers to gain an appreciation for the various types of mouth gags available for simple and complex surgical procedures. This article serves as a review of the history and motivation behind invention of mouth gags.

Pediatric bite block