TY - JOUR
AU - MD, G. D. Warden,
AB - Abstract Patients who have sustained a facial burn often contend with cosmetic and functional challenges, including microstomia. Many devices have been created by a variety of professionals to provide oral stretching. These devices can be classified as intraoral or extraoral and deliver a stretch either horizontally, vertically, or circumorally. The purpose of this article is to present a comprehensive review of oral-stretching devices. The dynamic properties of scar tissue in the early stages of scar maturation, unless influenced by an opposing force, quickly shortens and frequently leads to contractures.1,2 A variety of interventions are used to manage the scarring process, some of which include positioning, pressure, splints, and exercises.1,3 These interventions are intended to reduce scarring and maintain function.4 When the perioral region is involved, there are concerns not only with cosmetic appearance but also with function and hygiene. Microstomia can inhibit dental and skeletal development in addition to creating difficulties with eating and speech.5,6 Furthermore, microstomia makes dental hygiene difficult and can be hazardous when attempting to administer general anesthesia.6,7 There is a wide range of protocols followed to prevent or manage microstomia, including initiation of the appliance, frequency, and duration of use. The appliances are presented in three major categories based on the type of stretch provided (horizontal, vertical, and circumoral) and then grouped based on whether the device is intraoral or extraoral. The majority of the devices are custom-made. A description of the appliance itself, along with its use, advantages and disadvantages, is discussed. METHODS A literature review was performed by means of a MEDLINE search. Articles that were published between 1972 and 2002 were included. Additional references were located using the reference lists from the obtained articles. RESULTS A total of 37 devices were identified. The devices were categorized into three groups based on the type of stretch that was elicited: horizontal, vertical, or circumoral. The devices were then placed into subgroups based on their attachment or the means by which they were secured to elicit the stretch (extraorally or intraorally). Twenty-five devices were placed in the group that provided a horizontal stretch (13 extraoral, 12 intraoral); four appliances were identified as vertical stretching devices (one extraoral, three intraoral); and eight were placed in the circumoral stretching group (five extraoral, three intraoral). DISCUSSION Horizontal Stretching Devices Extraoral. The Microstomia Prevention Appliance™ (MPA; MPA Company, Dallas, TX) was developed as a result of difficulties faced with the initial static stretching device created at the University of Iowa College of Medicine (Figure 1).8,–10 The MPA is a commercially available device that consists of two acrylic sections that fit in the oral commissures. Between these acrylic sections are two curved stainless-steel bars and a set screw used for securing the device. With the set screw loosened and the appliance collapsed, each acrylic piece is placed in the commissure. The arrow, which is imprinted on one of the pieces, points cephalad. Once the MPA is adjusted to the desired expansion, the set screw is tightened. It can be adjusted in 2-mm intervals and is available in four sizes, which range in expansion from 3.8 to 9.5 cm. This device can be inserted, worn, and removed with ease and minimal discomfort.8,–10 It can also be used as a dynamic device by loosening the set screw and placing an elastic band into the grooves of the protruding metal pieces.10 Heinle et al9 demonstrated the cost-effectiveness of this device by revealing a decrease in operative procedures and length of stay in the hospital when compared with records from the 4 years before MPA use. Disadvantages include the inability to prevent lower lip eversion when there is contracting scar adjacent to the vermillion border,8 the potential for skin breakdown at the commissures,9,10 and the inability to retain oral secretions.9,10 Figure 1. View largeDownload slide The microstomia prevention appliance. Medium and large sizes are shown. Figure 1. View largeDownload slide The microstomia prevention appliance. Medium and large sizes are shown. Fowler and Pegg11 found conventional MPAs difficult to insert and once inserted, they could be quite uncomfortable, thus influencing compliance. They also found that if the screw was not tightened firmly, the device could loosen and not provide an adequate stretch. As a result, the Modified Microstomia Prevention Splint (MMPS) was created (Figure 2). The device is composed of two pieces, each one made of a small piece of thermoplastic material molded around the end of a Kirschner wire. The wire is brought to a 90° angle approximately ¼” distal to the end of the splint material. The most distal end of the wire is formed into a hook. Once both pieces of the device are fabricated, two strips of splint material are wrapped around the wires to keep them aligned while the device is in use. The device is used by placing the thermoplastic material at each corner of the mouth. A narrow Velcro® (Velcro USA, Inc., Manchester, NH) loop strap is brought around the proximal end of the wire (close to the splint material) and attaches to Velcro® hook, which has been stitched to the facial garment. If a pressure garment is not worn on the face, an elastic strap that passes around the head can be used to elicit the stretch. Initially, the MMPS is applied for 2 hours then removed for 2 hours, day and night. It is increased to all-night wear with the day schedule of 2 hours on and 2 hours off. The distance between the hooks is used as a guide for correct positioning. Advantages include its ease of use and the reduction of discomfort when inserted. Disadvantages include the potential for breakdown at the commissures and lip eversion. Figure 2. View largeDownload slide The modified microstomia prevention splint. The splint on the right shows modifications that eliminate pressure applied to the oral mucosa. Reprinted from Fowler D, Pegg S. Modified microstomia prevention splint. Burns 1986;12:371–3, with permission from Elsevier Science. Figure 2. View largeDownload slide The modified microstomia prevention splint. The splint on the right shows modifications that eliminate pressure applied to the oral mucosa. Reprinted from Fowler D, Pegg S. Modified microstomia prevention splint. Burns 1986;12:371–3, with permission from Elsevier Science. Four articles describe an extraoral approach to managing microstomia by which the commissures are stretched by means of retractors attached to a headgear or neck strap.12,–15 Reisberg et al12 made a wax impression of the uninvolved commissure, cheek, and buccal mucosa. From this impression a silicone mold is made into which an acrylic resin is placed to fabricate the conformer for the commissures. A channel is created in the conformer to provide placement for a wire. The protruding end of each wires is bent for attachment to the headgear strap. With the conformers positioned at each commissure, traction is provided in the horizontal plane to a distance determined by measuring from the facial midline to the uninvolved commissure while the patient is making the widest smile. The device is worn continuously, except for meals, for 4 to 6 months (depending on the extent of the injury) and then only at night for another 4 to 6 months. The authors report there is a decreased chance of developing pressure necrosis by ensuring that the distance from the center of the mouth to the normal commissure (when the patient smiles) is not exceeded by the force of traction. They also state that the silicone mold can be reused to make other acrylic conformers. Josell et al13 presented a similar device that uses a directional force headgear and covered wire (Figure 3). Orthodontic wire is bent as described in the article, threading IV tubing over the wire after the initial bend is placed in the wire. Rivets are used to attach four adjustable elastic headgear straps to the headgear. The covered wire is then attached to the headgear straps. The appliance is inserted on the injured side first. Once both sides are inserted, there should be equal retraction on both sides. The wires and straps are adjusted as needed to achieve the desired stretch. The appliance is worn as much as possible but can be removed for meals. This appliance is easy to use, can be premade, and can be adjusted simply. Figure 3. View largeDownload slide Adjustable elastic straps secure the covered wire to the headgear. The retraction should be the same on both commissures. The wires can be adjusted to add a vertical component to the stretch. Reprinted with permission from the American Academy of Pediatric Dentistry, 211 East Chicago Avenue, Suite 700, Chicago, Illinois 60611–2663. Figure 3. View largeDownload slide Adjustable elastic straps secure the covered wire to the headgear. The retraction should be the same on both commissures. The wires can be adjusted to add a vertical component to the stretch. Reprinted with permission from the American Academy of Pediatric Dentistry, 211 East Chicago Avenue, Suite 700, Chicago, Illinois 60611–2663. Schneider14 presented a reverse-pull headgear to manage a burn injury to the commissure. The reverse-pull headgear consists of a chin cup, forehead rest, and right and left wire outer bows (covered with acrylic) that retract the commissures in a position that is equidistant from the midline. Elastic bands attach the headgear to headgear pads, which are secured to a bonnet worn by the patient. The device is worn at all times except for bathing and eating. The treatment period would depend on the extent of the injury. Advantages include ease of use, the fact that the teeth are not required to support the device, and the ability to adjust the tension for a progressive stretch. Because the area of contact is small, there is a potential for developing pressure areas at the commissures. The device presented by Sykes15 also incorporates the use of retractors and a headgear. It is fabricated by making putty impressions of the edges of the mouth, the buccal mucosa, and the cheek. Hooks are inserted into the putty at an appropriate distance from the headgear (the author recommends 5 cm). The putty impressions are then converted into acrylic lip retractors. Once the lip retractors are adjusted as needed to fit comfortably, they are connected to the headgear by elastic bands. The force of the pull on the commissures can be increased by using shorter elastics. The potential for developing pressure necrosis at the commissures is reduced as a result of the larger area of contact with the commissure. Another extraoral appliance that stretches the commissures in the horizontal direction is one in which the posts are attached to a face mask.16 The patient is casted for a face mask after the typical protocol.16 Two U-shaped posts that will retract the commissures are fabricated separately with acrylic. One post is attached to the facemask on the unaffected side with additional acrylic. The post for the injured commissure is attached after measuring the midline-to-commissure distance on the unaffected side and doubling the distance. The facemask is anchored to an orthodontic headgear cap by elastic bands. The elastic bands are tied through holes in the facemask and then secured to hooks on the cap. The device is worn all the time except for meals and baths. The duration of use depends on the patient's healing. If used with young children, he or she would require anesthesia for casting for the facemask. There is a significant amount of time required for fabrication and a potential for developing pressure necrosis at the commissures. A similar device is described by Daugherty and Carr-Collins6 that involves the use of a neck brace rather than a facemask (Figure 4). A hard neck brace is fabricated for the patient in such a manner that the proximal portion of the brace rests over the mandible and anterior to the ear. Acrylic hooks are used to retract the commissures. Tension is provided by means of surgical tubing tied through the end of the commissural hook and attached to the neck brace. Although not stated by the authors, it is suggested that this device be worn at all times except for exercise, meals, and baths for a period of 4 to 6 months then change to nights only until the scar is mature. Figure 4. View largeDownload slide Acrylic hooks attach to a hard neck brace by means of surgical tubing to retract the commissures. Used with permission from Richard R. Burn care and rehabilitation: principles and practice. Philadelphia: F. A. Davis; 1994. Figure 4. View largeDownload slide Acrylic hooks attach to a hard neck brace by means of surgical tubing to retract the commissures. Used with permission from Richard R. Burn care and rehabilitation: principles and practice. Philadelphia: F. A. Davis; 1994. Khan and Banis17 describe a device that stretches the commissures by means of an expansion screw (Figure 5). With the patient relaxed, the distance between the oral commissures is measured to determine the length of the device. Denture base material is molded into the commissures of the mouth. An expansion screw is placed between the two halves and attached to the commissure pieces with additional denture base material. With the screw in a closed position the splint should measure the same length as was previously determined. Once the device is in place, it is expanded by use of a small key. The patient wears the device daily for 6 to 8 hours. When the expansion screw has reached its maximum opening, new material can be added to the device. The authors report that since the patient controls the forces applied to the commissures, pressure wounds, and excessive pain can be avoided. Figure 5. View largeDownload slide Lateral (left) and anterior (right) views of the expansion prosthesis with the key used to activate the device. Reprinted from Kkan Z, Banis J. Oral commissure expansion prosthesis. J Prosthetic Dentist 1992;67:383–5, copyright 1992, with permission from Elsevier Science. Figure 5. View largeDownload slide Lateral (left) and anterior (right) views of the expansion prosthesis with the key used to activate the device. Reprinted from Kkan Z, Banis J. Oral commissure expansion prosthesis. J Prosthetic Dentist 1992;67:383–5, copyright 1992, with permission from Elsevier Science. Two extraoral devices use thermoplastic material for fabrication. The mouth conformer described by Denton and Shaw18 is composed of two thermoplastic conformers and elastic straps. Measurements are taken for the length and width of the conformer. The length is the distance from the corner of the mouth to the temporomandibular joint bilaterally. The width needs to be narrow enough so as not to impinge on the gingivae. With these measurements, an oblong pattern is drawn with the center being slightly narrower for better contour in the commissures. The pattern is traced onto thermoplastic material and cut out. The conformer is molded to the corner of the mouth with one end of the conformer against the buccal mucosa and the other end on the exterior surface of the cheek. The patient brings his/her teeth together. Pressure is applied to the interior portion of the conformer with the index finger and an opposing pressure to the exterior portion with the thumb. The contour is shaped as needed for better comfort at the corner of the mouth. The conformer is removed when it is firm and a 1-cm elastic strap is riveted to the end of the exterior portion of the mouthpiece. This strap should be long enough to reach across the back of the head from one mouthpiece to the other. A second strap is attached by rivets to the first strap just anterior to the ears. It should be long enough to reach across the back of the neck. The device is initially worn for one hour twice a day and then the wearing time is gradually increased. As with many of the devices, there is a potential for developing skin breakdown. Yotsuyanagi and Sawada19 present an oral splint that is composed entirely of thermoplastic material (Figure 6). Two pieces of thermoplastic material are molded to each oral angle. These pieces act as lip holders to retract the commissures. Another longer piece is shaped into an oral frame that is bent in the center. The bend in the frame allows the device to expand against the oral angles. The lip holders are then bonded to the oral frame. The splint is placed in the patient's mouth and adjusted as needed to elicit the desired stretch. This device is easy to use, fabricate and modify. Figure 6. View largeDownload slide Lateral (left) and anterior (right) views of an oral splint composed entirely of thermoplastic material. Reprinted from Yotsuyanagi T, Sawada Y. Expanding oral plastic splint for burn patients. Burns 1993;19:131–3, with permission from Elsevier Science. Figure 6. View largeDownload slide Lateral (left) and anterior (right) views of an oral splint composed entirely of thermoplastic material. Reprinted from Yotsuyanagi T, Sawada Y. Expanding oral plastic splint for burn patients. Burns 1993;19:131–3, with permission from Elsevier Science. The Expansile Removable Appliance presented by Silverglade and Ruberg5 is similar to the device previously described by Khan and Banis17 in that two commissural pieces are connected by an expanding device, a Hyrax screw in this case (Figure 7). The acrylic pieces are placed at each commissure and the Hyrax is expanded until the appropriate stretch is achieved. The potential for developing pressure areas is decreased as the result of a larger area of contact with the commissure and it provides a slight vertical stretch as well. These authors presented another extraoral device they named the Tissue-Borne Removable Splint (Figure 8). Acrylic tusks (which measure ∼3 cm in length and 5 mm in diameter) are connected by an acrylic bar that is 1 cm wide and 5 mm in diameter. The tusks are placed inside the mouth and are held in place by the cheeks. The acrylic bar connecting the tusks rests outside the mouth, just anterior to the lips. Although the authors do not comment on the ease of modifying this device, they do state that it is easy to fabricate and use. Figure 7. View largeDownload slide The expansile removable appliance can be expanded slowly thereby decreasing discomfort and improving compliance. Reprinted with permission from Silverglade D, Ruberg RL. Nonsurgical management of burns to the lips and commissures. Clin Plast Surg 1986;13:87–94. Figure 7. View largeDownload slide The expansile removable appliance can be expanded slowly thereby decreasing discomfort and improving compliance. Reprinted with permission from Silverglade D, Ruberg RL. Nonsurgical management of burns to the lips and commissures. Clin Plast Surg 1986;13:87–94. Figure 8. View largeDownload slide The tissue-borne removable splint is recommended for use with older patients only. Reprinted with permission from Silverglade D, Ruberg RL. Nonsurgical management of burns to the lips and commissures. Clin Plast Surg 1986;13:87–94. Figure 8. View largeDownload slide The tissue-borne removable splint is recommended for use with older patients only. Reprinted with permission from Silverglade D, Ruberg RL. Nonsurgical management of burns to the lips and commissures. Clin Plast Surg 1986;13:87–94. Intraoral. Silverglade and Ruberg5 presented the Tooth-Borne Removable Splint, an intraoral device used to stretch the commissures (Figure 9). An impression is made of the maxillary arch, which is then poured in dental stone. Acrylic is poured over the teeth with supportive tusks projecting from the labial aspect. The placement of the tusks is determined in the manner described by the authors. The device is retained in position by the teeth. Once in place, tension is applied to the commissures by the tusks. While the device is easy to use, teeth must be present for anchorage. Figure 9. View largeDownload slide The tooth-borne removable appliance applies tension to the commissures by means of supportive tusks. Reprinted with permission from Silverglade D, Ruberg RL. Nonsurgical management of burns to the lips and commissures. Clin Plast Surg 1986;13:87–94. Figure 9. View largeDownload slide The tooth-borne removable appliance applies tension to the commissures by means of supportive tusks. Reprinted with permission from Silverglade D, Ruberg RL. Nonsurgical management of burns to the lips and commissures. Clin Plast Surg 1986;13:87–94. A thermoplastic device created by Gorham20 stretches the angles of the mouth and lips and is held in place by a biteplane molded to the upper and lower teeth. The length of the splint material is twice the horizontal width of the relaxed, closed mouth. The width of the material is ∼ 1½”. The preheated material is overlapped lengthwise on itself by 1½” on each end and pressed firmly together to form a ring. A stainless-steel dowel rod (¼” by 4”) is placed through each ring and gently pulled away from each other in a parallel direction to form an oblong piece with the overlap on top. The device is held by the dowels and placed in the patient's mouth so that approximately ¼” of the ring extends outside. The patient then bites down once, holding this position while using his/her tongue to mold the material on the roof of the mouth. While the patient does this, the dowels are pulled apart until the desired stretch is achieved. The splint is removed while the material is firm and the roof of the mouth portion is cut out. Having this portion removed makes speech easier when the device is used. Once the splint is hard, the dowels are removed. The splint is used at night and/or during the day when it does not interfere with the patient's daily activities. Several authors discuss splints that are quite similar in use.21,–30 Each is an intraoral device fabricated with dental material that consists of protruding “prongs” that place a horizontal stretch on the commissures (Figure 10). An impression is made of the maxillary arch,21,24,25,27,30 the maxillary and mandibular arches22,23,26 or the palate and maxillary arch.28,29 An acrylic prosthesis is fabricated from the impression.21,–29 One prosthesis is fabricated with surgical tray material and cheek retractors (Figure 11).30 Some devices also use chrome crowns,21 wire,21,28,29 elastic bands,29 and/or ball or Adams clasps25 for fabrication. Once the device is fabricated and any necessary adjustments are made, it is placed in the patient's mouth. Depending on the patient's age and whether or not the device is fixed or removable, he or she may need to be under general anesthesia for insertion. The fixed devices are either cemented to the teeth21 or secured with wire22 or sutures.26 The removable appliances are either held in place by the teeth,23,–25,27,29 the teeth with denture adhesive applied to the palatal section of the device,28 or by denture adhesive alone.27 One device can be secured either to the teeth or, for patients without teeth, by an orthodontic headgear.30 The majority of these intraoral devices have bilateral protruding “prongs” or posts21,23,–30 whereas one device is fabricated with only a unilateral post.22 Salman et al22 report that one post was used on the injured commissure only to reduce the risk of developing pressure necrosis on the uninvolved commissure and to improve comfort and function. Although all 10 of these intraoral devices apply a horizontal stretch on the commissure(s), the device described by Jackson29 is the only one that provides a dynamic stretch (Figure 12). The advantages with the fixed appliances are that they can be used with young children and compliance is not an issue. Another advantage is that teeth are not always necessary.22,26,27,30 The disadvantages include fabrication time, expense and general anesthesia may be required for fabrication and/or insertion. Figure 10. View largeDownload slide Superior view (left) of an intraoral device. The device in place (right) with the commissural posts retracting the commissures. Reprinted from Colcleugh RG, Ryan JE. Splinting electrical burns of the mouth in children. Plast Reconstr Surg 1976;58:239–41, with permission from Lippincott Williams and Wilkins. Figure 10. View largeDownload slide Superior view (left) of an intraoral device. The device in place (right) with the commissural posts retracting the commissures. Reprinted from Colcleugh RG, Ryan JE. Splinting electrical burns of the mouth in children. Plast Reconstr Surg 1976;58:239–41, with permission from Lippincott Williams and Wilkins. Figure 11. View largeDownload slide An intraoral device fabricated with surgical tray material and cheek retractors. Reprinted from Ampil JP, Newell L, Taylor P. A simplified prosthesis for the treatment of burns to the oral cavity. J Prosthetic Dentist 1988;59:608–10, with permission from Elsevier Science. Figure 11. View largeDownload slide An intraoral device fabricated with surgical tray material and cheek retractors. Reprinted from Ampil JP, Newell L, Taylor P. A simplified prosthesis for the treatment of burns to the oral cavity. J Prosthetic Dentist 1988;59:608–10, with permission from Elsevier Science. Figure 12. View largeDownload slide A dynamic intraoral device that uses elastic bands to move the commissural pieces in the horizontal plane to elicit the stretch. Reprinted with permission from the American Academy of Pediatric Dentistry, 211 East Chicago Avenue., Suite 700, Chicago, Illinois 60611–2663. Figure 12. View largeDownload slide A dynamic intraoral device that uses elastic bands to move the commissural pieces in the horizontal plane to elicit the stretch. Reprinted with permission from the American Academy of Pediatric Dentistry, 211 East Chicago Avenue., Suite 700, Chicago, Illinois 60611–2663. Vertical Stretching Devices Intraoral. Many of the early devices used to manage microstomia addressed only the horizontal component of mouth opening. Paff et al31 pointed out that techniques that previously had been used to manage microstomia did not address the vertical contracture that often occurred. They presented a treatment program that included vertical static stretching using tongue blades to improve mouth opening and minimize lower eyelid ectropion and purse string contractures of the nasolabial folds. Although tongue blades have been found to be effective in delivering a vertical stretch31,32 the isolated pressure placed on the front teeth could cause them to sublux.33 Williams and Baker32 discussed a vertical device in their treatment program, the Molt Mouth Prop, a commercially available dental device (Figure 13). The silicone tips of this dental device are placed between the upper and lower teeth (on the lateral aspect of the mouth). A locking mechanism helps maintain the position. The article merely presented the device and did not elaborate on any specifics regarding its use. There would be no fabrication time and it seems easy to use. However, teeth are required. Figure 13. View largeDownload slide The silicone tips of the molt mouth prop are placed between the upper and lower teeth. A locking mechanism helps maintain the position. Figure 13. View largeDownload slide The silicone tips of the molt mouth prop are placed between the upper and lower teeth. A locking mechanism helps maintain the position. A dynamic splint presented by van Straten34 was developed to exercise the temporomandibular joint and improve range of motion (ROM) in the direction of vertical mouth opening (Figure 14). The splint is about the size of the mandibular arch and is made with thermoplastic material and a spring. A piece of thermoplastic material is folded over a spring so that the ends of the material are on either end of the spring. The spring is secured with additional pieces of thermoplastic material. The splint is padded with foam lining to increase comfort. Specific advantages and disadvantages were not stated in the article. This appliance appears to be inexpensive and easy to fabricate. Furthermore, it appears that the device is placed between the upper and lower teeth only, thereby minimizing the risk for skin breakdown. Figure 14. View largeDownload slide A dynamic splint used to exercise the temporomandibular joint. Figure 14. View largeDownload slide A dynamic splint used to exercise the temporomandibular joint. Extraoral. Sela and Tubiana35 present a splint that is fabricated with dental material and uses a Hyrax screw at the angles of the mouth to create the stretch (Figure 15). Individual trays for the lips need to be fabricated and impressions of the mouth need to be taken. Aside from requiring dental materials and an extended period of time to fabricate, this device has distinct advantages. Pressure is distributed across a large area, it can be adjusted (within the limits of the screws) to accommodate a patient's progress and it is easy to apply. Figure 15. View largeDownload slide Anterior view of splint with the key used to activate the screw (left). Anterior view of splint (fully opened) in patient's mouth (right). Reprinted from Sela M, Tubiana I. A mouth splint for severe burns of the head and neck. J Prosthetic Dentist 1989;62:679–81, with permission from Elsevier Science. Figure 15. View largeDownload slide Anterior view of splint with the key used to activate the screw (left). Anterior view of splint (fully opened) in patient's mouth (right). Reprinted from Sela M, Tubiana I. A mouth splint for severe burns of the head and neck. J Prosthetic Dentist 1989;62:679–81, with permission from Elsevier Science. Circumoral Stretching Devices Extraoral. McGowan7 was the first to present a circumoral appliance. He created this custom-made device after finding that his patient continued to have difficulty with functional opening of the mouth because of tight vertical bands of scar tissue located at the angles of the mouth despite using an appliance similar to the MPA. His device is fabricated in a manner similar to the MPA whereby two acrylic pieces are connected with screws to provide a stretch (Figure 16). The acrylic pieces are much larger and are shaped in an arc to be placed on the upper and lower lips. The device provides a stretch both horizontally and vertically. It is worn all the time except for meals initially. The wearing schedule is decreased based on how well the patient can maintain the improved opening. There is a decreased potential of developing pressure areas secondary to even distribution of pressure. This device is uncomfortable when worn for long periods of time with patients complaining of cracked lips and sore throats. Fabrication time and expense are other factors to consider with this device. Figure 16. View largeDownload slide Shaping the acrylic pieces in an arc provides a stretch horizontally and vertically. Reprinted from McGowan RH. Prevention of microstomia following facial burns. Br Dental J 1980;139:83–4, with permission from Nature Publishing Group. Figure 16. View largeDownload slide Shaping the acrylic pieces in an arc provides a stretch horizontally and vertically. Reprinted from McGowan RH. Prevention of microstomia following facial burns. Br Dental J 1980;139:83–4, with permission from Nature Publishing Group. Another custom-made device is presented by Clark and McDade36 (Figure 17). The device is constructed in two halves. Each half is constructed with a clear lip retractor. The end of the retractor is bent inward slightly and covered with acrylic. Vertical posts are placed across the curve of the retractor (at the outer flange of the lip trough) and secured with wire and acrylic. Two horizontal bars and four universal joints connect the two halves of the device. Each half of the device is inserted into the mouth separately. The paddles fit between the buccal mucosa and alveolar ridge and the retractor grooves seat on the vermillion lip. The horizontal rods are threaded into the universal joints, which are tightened slightly. Both pieces are moved apart simultaneously as an external rotational force is placed on the buccal paddle one at a time. Once the desired tension is achieved, the universal joints are tightened to maintain the position. The authors suggest the device be worn as much as possible but have found that it is more likely for patients to get prolonged use at night when sleeping. The stated benefits include the distribution of pressure over a larger area so as to decrease the likelihood of developing pressure areas, the ability to gas sterilize the device for use with multiple patients, and providing an outward pressure to both cheeks in addition to stretching the mouth. Stated disadvantages include the inability to control eversion of the lip when there is contracting scar at the vermillion border, discomfort with its use and patients lacking enough manual dexterity require assistance to insert the device. Figure 17. View largeDownload slide An adjustable appliance that can be gas sterilized for use with multiple patients. Reprinted from Clark W, McDade G. Microstomia in burn victims: a new appliance for prevention and treatment and literature review. J Burn Care Rehabil 1980;1:33–6, with permission from Lippincott Williams and Wilkins. Figure 17. View largeDownload slide An adjustable appliance that can be gas sterilized for use with multiple patients. Reprinted from Clark W, McDade G. Microstomia in burn victims: a new appliance for prevention and treatment and literature review. J Burn Care Rehabil 1980;1:33–6, with permission from Lippincott Williams and Wilkins. A one-piece cheek retractor and two limiting straps are used to fabricate the device presented by Shehan and Medford (Figure 18).37 The limiting straps are strips of plastic, which are typically used with orthodontic headgear. The plastic is a durable material with a series of holes. The straps are wired to the retractor at the inner and outer curvature of the bow portion on the retractor. An acrylic resin is placed over the area of attachment to assist in stabilizing this attachment. The retractor is fitted to the patient's mouth. Once the appropriate degree of traction is achieved, the straps are wired together and fixed in this position. The patient wears the device all night. During the day, it is removed for 1 hour after 3 hours of wear. Stated advantages are that little oral manipulation is required for fabrication, it is inexpensive and easy to use. Pressure distribution is an advantage not stated whereby pressure is distributed over a large surface area, reducing the likelihood of developing pressure areas. Stated disadvantages are that it may break from prolonged stress and if the patient has large lips, the appliance may slip out. This problem can be avoided, however, by turning the appliance upside down so the bow is up instead of down. Figure 18. View largeDownload slide The one-piece retractor and limiting straps (left). The limiting straps are secured to the retractor with wire and acrylic resign (right). Reprinted from Medford HM, Shehan MT. A simplified splint for decreasing or preventing stenostomia in patients with burns. Spec Care Dentist 1986;6:36–7. Figure 18. View largeDownload slide The one-piece retractor and limiting straps (left). The limiting straps are secured to the retractor with wire and acrylic resign (right). Reprinted from Medford HM, Shehan MT. A simplified splint for decreasing or preventing stenostomia in patients with burns. Spec Care Dentist 1986;6:36–7. A similar device is presented by Madjar et al.38 Wax patterns of both sides of the mouth are made that are then replaced with acrylic resin. These acrylic lip holders are positioned in the patient's mouth and a stainless-steel wire, which is formed into the shape of an omega, is adapted to them so that the forces are directed laterally and distally. The wire is connected to the lip holders with acrylic resin. The patient is instructed to wear the device as much as possible during the day and evening. The authors report that because this device is not anchored to the teeth, no impressions have to be taken, and no intraoral adjustments have to be made. Also, because the forces can be applied to a broad section of the lips, the likelihood of developing pressure areas is decreased. It is also easy to use. Although the authors state that this device can be used only with facial burns that have a symmetrical nature, others could argue this point. Because the device is anchored to both labial commissures, it would be a good choice to use with patients who suffered a circumoral burn. However, its use should not be limited to that group. The final extraoral device that provides a stretch both vertically and horizontally is the Vancouver Microstomia Orthosis presented by Conine et al (Figure 19).39 The patterns used for fabricating this device are drawn onto unperforated thermoplastic material as described by the authors. Kirschner wire (approximately 10 cm in length) is formed into a U shape. The distance between each end of the wire is the same as the distance between the commissures. A U-shaped piece of thermoplastic material is shaped around the Kirschner wire except for the ends which remain flat. Another smaller piece of thermoplastic material (measuring 4.5 cm by 3 cm) is molded against the patient's commissure. At least 2.5 cm of the material should be molded inside the mouth to aid in retention of the device. The same procedure is followed for the other commissure. The edges of both commissural pieces are flared to prevent the edges from cutting into the upper or lower lip and are attached to the U-shaped spring. The commissural portion is angled at 140 degrees upward and 160 degrees backward in relation to the wire spring. The device can be used as a static or dynamic device. If a static device is preferred, a hole is drilled into both sides of the spring (on the medial aspect). An outrigger wire is cut and fit into the holes to act as a static bar and maintain the position. If using the static bar, it is put in place after the device is positioned in the patient's mouth and before the device is removed. The device is initially worn 10 minutes every 2 hours then gradually increased to 30 minutes every hour when awake. Once ROM has stabilized, the device is discontinued and the patient performs facial exercises. If ROM does not maintain, the device is worn 2 to 3 hours daily until the scars mature. Figure 19. View largeDownload slide Dynamic Vancouver microstomia orthosis in patient's mouth (left). Anterior view of Vancouver microstomia orthosis with static bar (right). Reprinted from Conine T, Carlow D, Stevenson-Moore P. The Vancouver microstomia orthosis. J Prosthetic Dent 1989;61:476–83, with permission from Mosby Publishing. Figure 19. View largeDownload slide Dynamic Vancouver microstomia orthosis in patient's mouth (left). Anterior view of Vancouver microstomia orthosis with static bar (right). Reprinted from Conine T, Carlow D, Stevenson-Moore P. The Vancouver microstomia orthosis. J Prosthetic Dent 1989;61:476–83, with permission from Mosby Publishing. Intraoral. Two articles discuss the Therabite® Jaw Positioner (Atos Medical, Milwaukee, WI), which is a commercially available device that addresses the vertical component of mouth opening along with the horizontal opening while distributing pressure across a greater area.40,41 There are two types of Therabite® orthoses available. One is a hand-held, hinged jaw exerciser as discussed by Costa et al.40 The other, presented by Ridgway and Warden,41 is an orthosis with biteplates moving vertically along the base (Figure 20). Each type is made of a high-density nylon and consists of upper and lower mouthpieces that are available in adult and pediatric sizes. Self-adhesive foam cushions are also available to place on the mouthpieces. The hand-held device is used by squeezing the lever to open the mouthpieces and is intended for performing active opening and closing exercises. The smaller Therabite® has a nylon locking screw that tightens in any position to maintain a static stretch. There are many advantages with using the Therabite®. Because it is commercially available, no time is spent on fabrication. It is easy to use and does not contribute to lip eversion. Although it is expensive, it can be cleaned and used with multiple patients. Figure 20. View largeDownload slide Two types of Therabite® Jaw Positioners. Figure 20. View largeDownload slide Two types of Therabite® Jaw Positioners. A device similar to the Therabite® was presented by Dougherty et al42 (Figure 21). A 4” square and ∼1/8” thick piece of thermoplastic material is used to create this device. Two matching pieces are cut out of the material, each composed of a mouth portion and long handle portion. The width of the mouth portion depends on the size of the patient's mouth and the extent of contracture. The width of the handle portion is approximately the same width as a tongue blade. A thin adhesive foam is placed on one side of the mouth portion only and repeated with the second piece of material. When the two pieces of material are placed together, the upper and lower teeth will rest on the foam. At the end of the handle portion a short section of the material is brought to a 90° angle. A rubber band is placed around the handle to help keep the two pieces of material aligned. Tongue blades are inserted between the two pieces to elicit the stretch. Approximately 5 minutes of massage is performed to each commissure before inserting the device into the patient's mouth. Depending on the extent of contracture, a manual horizontal and/or vertical stretch may be needed to insert the device. The device is inserted by sliding it into the patient's mouth at an angle. No tongue blades should be in the device when it is positioned in the patient's mouth. If the device is difficult to put into the patient's mouth, a longer manual stretch may be needed or the size of the device may need to be modified. Tongue blades are placed one at a time between the two pieces of the device at appropriate intervals. The number of tongue blades used depends on the extent of contracture and the desired stretch. Once all of the tongue blades have been placed in the device, the stretch is maintained for approximately 5 minutes. The tongue blades are removed from the device before it is taken out of the patient's mouth. The patient should use the device three times a day until the scars mature or until the ROM with mouth opening can be maintained. The device is inexpensive and distributes pressure across a broad area. Moreover, there is minimal risk for developing pressure areas. Figure 21. View largeDownload slide Lateral view (top) and superior view (bottom) of the thermoplastic mouth stretcher. Figure 21. View largeDownload slide Lateral view (top) and superior view (bottom) of the thermoplastic mouth stretcher. MacMillan et al43 created a removable intraoral device that resembles a mouthguard worn by athletes (Figure 22). Impressions are taken of the patient's dental arches from which polyvinyl molds are created. The molds are inserted into the patient's mouth with the aid of lubricant and kept in place initially for 2 days. After this initial period, it is worn through the night and for two 2-hour periods during the day. The authors present many advantages with using this device. It is easily modified by adding more material as the degree of constriction decreases. It is easy to use and well tolerated by patients. The patient in the case report presented had no difficulties with developing pressure areas. Figure 22. View largeDownload slide This intraoral polyvinyl mol can be modified by adding more material as the degree of constriction decreases. Reprinted from MacMillan A, Oliver A, Richardson L, Reade P. An intraoral splint for the prevention of microstomia from facial burns. Burns 1991;17:72–4, with permission from Elsevier Science. Figure 22. View largeDownload slide This intraoral polyvinyl mol can be modified by adding more material as the degree of constriction decreases. Reprinted from MacMillan A, Oliver A, Richardson L, Reade P. An intraoral splint for the prevention of microstomia from facial burns. Burns 1991;17:72–4, with permission from Elsevier Science. CONCLUSIONS These devices were created by a variety of professionals including dentists, prosthodontists, occupational therapists and physical therapists. Although each appliance has advantages and disadvantages, no orthosis will be ideal for every patient (Table 1). Gay44 noted that devices used with patients having circumoral burns need to stretch vertically, horizontally and obliquely in order to limit contraction in more than one plane, thereby eliminating appliances such as the MPA for use with such patients. Clark and McDade36 pointed out that appliances which use external elastic straps might be difficult to tension and may not be able to be used early in the patient's treatment because of open wounds or recently placed skin grafts. Josell et al13 noted that removable appliances may not produce good results because these devices rely on the patient's compliance. Correspondingly, a survey conducted by Walling et al45 found that professionals listed poor compliance as the number one problem in treating patients with facial burns. With this in mind, it is apparent that the professional needs to consider several factors when choosing an appliance such as the patient's age, dentition and the location and depth of the burn. Also, the appliance should be simple to fabricate, easy to use and well tolerated by the patient when it is in use. Considering the difficulty in finding an appliance that is ideal for a patient one might choose to use a combination of devices.32,34,40 It is important to remember that a mouth appliance is but one aspect of the patient's treatment program. Exercise,1,2,4,31,32,45 pressure,1,2,8,31,32,41,45 and massage31,–33,41,45 are essential and must be included as well for optimal patient outcome. Table 1. Comparison of oral appliances View Large Table 1. Comparison of oral appliances View Large Although there is debate regarding the best course of treatment for facial burns, there is agreement that early splinting decreases the need for surgical reconstruction2,3,8 and splinting should continue until the scar is mature.2,5,28 Most of the appliances reviewed are intended for continuous wear (except for meals and hygiene with the removable appliances) for an average of 6 months then changing to nights only until the scar matures. Some authors discuss using an oral appliance several times a day for a short period of time (10–20 minutes) in conjunction with pressure appliances,11,18,31,32,36,41,45 exercise,31,32,34,39,45 and/or massage.31,–33,41,42,45 Because appliances such as the MPA can promote upper and lower lip eversion, using a variety of splints would be of great benefit. 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TI - A Thirty-Year Review of Oral Appliances Used to Manage Microstomia, 1972 to 2002
JF - Journal of Burn Care & Research
DO - 10.1097/01.BCR.0000095517.97355.98
DA - 2003-11-01
UR - https://www.deepdyve.com/lp/oxford-university-press/a-thirty-year-review-of-oral-appliances-used-to-manage-microstomia-d3FgUvw74M
SP - 418
EP - 431
VL - 24
IS - 6
DP - DeepDyve
ER -