With interest, I have read the article by H uang , regarding a simple method to expand the joint space for temporomandibular joint (TMJ) surgery which is a welcome alternate method of increasing the visibility of the TMJ space. It would have been more appropriate to refer to the method as: a simple method to improve visibility of the joint space than to “expand” the joint space. Promoted by the paper, I would like to report a possible alternate technique based on similar methods with added advantages.
A simpler less time consuming method would be to make square blocks of polyether impression material (PIM) such as Impregum. The Impregum can be placed in a preformed metal rectangular mould of 2 cm × 1.5 cm × 1 cm dimension with the two largest dimension sides open. The Impregum is then placed within the mould with the one open end placed on a flat surface and allowed to set. The block is then easily removed via either open ends of the metal mould for use. The metal moulds can be reused repeatedly. The use of acrylic has some disadvantages, e.g., their limitations in their use in edentulous patients, the possibility of interfering with restorations, tooth fracture in carious teeth, a fixed fulcrum of rotation due to the occlusion interdigitating with the resin block resulting in the relationship between the maxilla and mandible being fixed at one point. There is thus no room for anterior or posterior movement-Hinge action and lateral excursion which maybe useful during surgery. The occlusion could be of of a Class I, II or III type with varying gonial angles, which may require the fulcrum of rotation to be adjusted accordingly. The use of the Impregum block allows for moving the fulcrum of rotation by moving it along the occlusal plane, which caters for the amount of force needed to distract the condyle as well as the degree of distraction. These blocks can be prefabricated and kept in storage with no requirement for immediate preoperative fabrication. The Impregum block is atraumatic, elastic, easily compressible and can be placed on mucosa as well as between teeth. The author has used a paediatric rubber mouth prop wrapped in gauze and placed horizontally between the intermaxillary space thus achieving similar results.
Another disadvantage of the method described is the possibility of assistant fatigue due to compressing the chin of the mandible during surgery. Continuous force being applied to the chin will lead to fatigue, which can compromise the surgical procedure especially if the condyle moves due to assistant fatigue. This could also lead to pressure induced damage to the skin if applied for long periods. It is suggested that 2 or 4 intraoral bone screws be inserted in the anterior maxilla and mandible and intermaxillary ligature wires placed to the desired position . This is by far a much lesser invasive procedure when opening the TMJ. This would relieve the assistant to assist the surgeon.
The added suggestions being made negates the need for the use of acrylic resin and the associated need for trimming, dealing with exothermic heat production, the possibility of a chemical taste and smell as well as distortion of the resin block during setting which will entail additional trimming and hence more time wastage.
The successful treatment of a large number of cases using K-wires and retractors as well as justification for its safe usage have been described by P erumal et al. , with no complications reported.
Different techniques maybe used to better visualize the TMJ space with adequate patient selection. However the technique described herein is safe to use in any patient type.