Indian Journal of Dental Research

: 2009  |  Volume : 20  |  Issue : 4  |  Page : 483--486

Prosthetic rehabilitation of patients with microstomia

DR Prithviraj, Sushma Ramaswamy, Soni Romesh 
 Department of Prosthodontics, Government Dental College and Research Institute, Fort, Bangalore, India

Correspondence Address:
D R Prithviraj
Department of Prosthodontics, Government Dental College and Research Institute, Fort, Bangalore


Microstomia is defined as an abnormally small oral orifice which can be due to various factors. Microstomia is a definite prosthodontic hindrance to carry out the different treatment successfully. To rehabilitate a patient with microstomia, successfully, the methods and designs incorporated in the prosthesis have to be modified. In the past, various techniques have been tried, incorporating certain biological and scientific methods to rehabilitate patients with microstomia. This article reviews the previously described treatment modalities in case of patients with microstomia.

How to cite this article:
Prithviraj D R, Ramaswamy S, Romesh S. Prosthetic rehabilitation of patients with microstomia.Indian J Dent Res 2009;20:483-486

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Prithviraj D R, Ramaswamy S, Romesh S. Prosthetic rehabilitation of patients with microstomia. Indian J Dent Res [serial online] 2009 [cited 2021 Jun 20 ];20:483-486
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Full Text

The reduction in maximal oral opening (microstomia) is a condition that hinders conventional prosthetic treatment of edentulous patients. [1] Prosthodontic treatment, particularly, is more complex due to the reduced oral opening. In particular, the fabrication of removable prostheses is further complicated by tongue rigidity and the constant adjustment required to accommodate the changing periphery. [2] This abnormality may be so severe as to prevent the insertion of stock impression trays. [1] Regardless of cause, the treatment of an edentulous patient with microstomia is difficult and often ingenious. [3]

 Prosthetic Limitations in Microstomia

Limited oral opening can be caused by head and neck radiation, reflex spasm, surgically treated head and neck tumors, microinvasion of the muscles of mastication, connective tissue diseases, fibrosis of masticatory muscles, facial burns, and reconstructive lip surgeries. [5] The condition can also result from genetic disorders such as partial duplication of chromosome 6q, Hallopeau-Siemens-type recessive dystrophic epidermolysis bullosa, Freeman-Sheldon (whistling face) syndrome, Burton skeletal dyslpasia, and diseases such as Plummer-Vinson syndrome or scleroderma. [6]

Limited mouth opening in patients is a common occurrence in prosthodontic practice. [7] A maximal oral opening smaller than the size of a complete denture can make prosthetic treatment challenging. [8] Different management techniques described are surgeries, use of dynamic opening devices, and modification of denture design. [5]

The first commissural splint innovation, suggested in 1975, radically altered the management of burns to the lip, by providing resistance to scar contraction in an effort to prevent microstomia. The main reason for fabricating a commissural splint is the need to minimize the effect of microstomia from multiple causes. The surgical management of microstomia is primarily designed to enhance primary healing and minimize tissue contracture. [9]

In prosthetic treatment, the loaded impression tray is the largest item requiring the intra-oral placement. During impression procedures, wide mouth opening is required for proper tray insertion and alignment which is not possible in patients with restricted mouth opening. In cases where microstomia is not manageable by surgeries or use of dynamic opening devices, a modification of the standard impression procedure is often necessary to accomplish this fundamental step in the fabrication of a successful prosthesis. [7]

Prosthetic rehabilitation of microstomia patients presents difficulties at all stages, right from the preliminary impressions to insertion of prostheses. Because such patients have small oral opening it may be extremely difficult to make impressions and fabricate dentures using conventional methods. [6] Making the impression represents the initial difficulty in prosthetic rehabilitation. [2]

 Impression Techniques in Microstomia

Recommended techniques to make preliminary impressions for patients with constricted oral openings have included (1) the use of stock impression trays of each half of the mouth for sectional impressions with heavy and light body silicone impression materials, (2) flexible impression trays made with silicone putty. The use of modeling plastic impression compound has also been described to make sectional impressions of edentulous arches. The mechanisms to connect sectional custom trays include hinges, plastic building blocks, orthodontic expansion screws or locking levers. Individual trays, except for the horizontal locking system, were connected only at the handle. [10]

A sectional stock tray system for making preliminary impressions was described by Robert. J. Luebke. Improved fit of the tray was possible for the individual dental arch because the two halves separately fitted to each side of the arch thus achieving better anatomical adaptation to the teeth and soft tissues. The tray halves were connected extra orally, and the impression was made. Using the above mentioned technique, impression making may be easier for patients with constricted oral openings because the two halves can be inserted independently, removed separately and reassembled extra orally. [11]

There have been several reports regarding fabrication of removable prostheses for patients with microstomia. Some treatments include hinged complete maxillary and mandibular dentures, the use of Co-Cr frameworks with clasps to hold sectional complete dentures, the use of a sectional complete denture joined by a post that slides into stainless steel tubing, and the use of cast Co-Cr hinges and swing-lock attachments for removable partial or complete dentures. There are a few reports on sectional complete dentures with dental magnetic attachments. There is literature available on the fabrication of a foldable, hinged posterior section with molar and premolar teeth and a second denture base on which anterior teeth were arranged. Sectional denture has been recommended, with the denture pieces connected by clasps. [12]

McCord et al. [13] described a complete sectional denture for a patient with microstomia which was designed in two halves; with the left side fitting into a beveled recess in the right side to give a more accurate location. Both halves were joined rigidly by a stainless steel post that was inserted into three tubes within the complete denture palate. The post, which was removable, was attached to the right maxillary incisor, which served both as a tooth and handle for the post. [13]

Naylor and Manor et al. [1] described a technique for the construction of a flexible prosthesis for the edentulous patient with microstomia that may be used to perform oral augmentation exercises to increase the vertical opening. The exercise regime is started initially by performing mouth stretching exercises to loosen the constricted facial skin and muscles. Oral augmentation exercise is started by placing a small bundle of tongue depressors between the occlusal surfaces of the opposing dentition or the dentures. Tongue depressors are aligned at an angle from the left premolar to the right molar region. Additional tongue blades are inserted one by one into the blade. The patient is encouraged to hold the mouth open at the maximum stretched position for several minutes to maximize disruption to the fibrosed facial tissues. Patient is suggested to exercise each morning to enjoy increased opening throughout the day. They claim that an improved aperture and enhanced flexibility of the facial skin and muscles may then permit satisfactory prosthetic treatment. [1]

Prosthodontic treatment modalities previously described are reviewed by Wahle et al. [3] They also introduced a new type of prosthesis that consists of a collapsible mandibular swing lock complete denture. The prosthesis incorporated a cast chromium frame work with a lingual hinge and a conventional labial swing lock. This design allows the prosthesis to be collapsible while maintaining structural durability. [3]

Suzukiy [14] introduced a design where the denture was fabricated in two parts to prevent denture deflection during chewing. For reinforcement of the hinges, the superior segment connected rigidly to the inferior segment using the telescopic system fabricated with the cast-on technique. Preliminary impressions were made with sectional stock trays and sectional custom made trays. The occlusal relationship was recorded with a sectional occlusal rim. The mandibular denture was composed of sectional superior and inferior segments. The superior segment spanned from the left second premolar to the right second premolar disjoined from the inferior segment. The inferior segment was collapsible with the hinge and swing lock attachment. For rigid connection of the two parts, a cast on technique was used with a Co-Cr-Ti alloy. [14]

Al-Hadi et al. [15] described the fabrication of a sectioned mandibular complete denture design for an edentulous patient with surgically induced microstomia. The design of the prosthesis incorporated acrylic resin connections in the form of dovetail with special direction to orient and secure the prosthesis. This design reduced the overall cost and simplified laboratory technique. [15] In another case report, [16] he described a simplified technique to treat a patient with limited mouth opening due to scleroderma. The treatment included the construction of a three-piece, sectional maxillary partial denture and a one-piece mandibular complete denture. [16]

Watanabe et al. [12] described a prosthesis which presented a cast iron-platinum magnetic attachment system applied to sectional collapsed complete dentures for an edentulous patient with microstomia. The use of lingual and palatal midline hinges and a cast iron-platinum magnetic attachment, made the sectional prosthesis successful, insertion was easier and provided adequate function in the patient's mouth. The author claims that the advantage of this design was the use of iron-platinum dental magnetic attachments which are useful for retention of the prosthesis because of their attractive forces. [12]

Cura et al. [17] described a technique used to fabricate mandibular and maxillary sectional trays and a foldable maxillary complete denture. The acrylic tray design was different in that for each tray, a total of four metal pins were prepared. In case of mandibular trays two of these pins were placed near the distal end and the other two near the anterior region. For maxillary tray two were placed on the residual ridges and two near the midline. An acrylic resin block with a 4 x 5 mm cross section that slid tightly on the pins was prepared. The trays were cut into two pieces with a steel disc and then joined with the acrylic resin block which slid onto the parallel pins. The maxillary denture base was prepared in two parts, right and left. These two were connected through a hinge mechanism and teeth arranged on these two halves were premolars and molars. On the foldable hinge base, a second acrylic resin record base on which the anterior teeth were arranged was prepared. The connection between the two bases was secured by means of two attachments fitted under the canine teeth with auto-polymerising resin. A piece of steel wire that could function as a lever on the line joining the maxillary denture pieces was used as a detachment slot. The mandibular denture was fabricated in one piece, as the denture could be rotated 90 degrees intra-orally. Thus a single-piece denture provided the patient with ease in placement and removal of the denture. [17]

Yenisey et al. [8] described sectional maxillary and mandibular trays and a collapsed mandibular denture for the total edentulous patient with microstomia caused by scleroderma. Preliminary impressions were made with a putty silicon impression material. For each special tray a total of four metal snaps were attached. Two female parts were attached on the canine regions and two were attached on molar regions. Another block carrying male parts of the snaps was constructed. In the mandibular tray only one block was adequate for the stability of the right and left parts. In the maxillary tray two blocks were constructed and they were joined together to provide stability. For the fabrication of the prosthesis lingual midline hinge was used, thus the collapsed denture was used successfully which allowed for the easy insertion and provided adequate function in the patient's mouth. The cast hinge design reduced the overall cost and simplified the laboratory technique. [8]

Geckili et al. [8] described a modified impression procedure with a two-piece impression tray and a method of fabricating a two-piece collapsible denture for a patient with limited oral opening as a result of the resection of a precancerous lesion on the maxillary lip. The custom tray was fabricated using auto-polymerising resin. The tray was sectioned mesiodistally along the middle of the palate. A tungsten carbide bur was divided into three pieces of equal length. One of the bur sections was placed on top of the right alveolar crest region and another on top of the left alveolar crest region of the tray. The third bur section was placed in the palatal midsection. All of the bur sections were fixed to the tray using auto-polymerising resin. The acrylic resin tray and the three bur sections were lubricated with petroleum jelly and a second tray, using the same acrylic resin was fabricated to slide on the bur sections of the first tray. This two piece custom-made tray allowed for a functional impression despite the difficulties associated with microstomia. The maxillary denture was designed in three pieces, with a locking mechanism that attached to stud attachments. A collapsible Cr-Co-Mo denture base for the premolars and molars and a triangular base for the anterior region were fabricated. Fabricating the denture in two pieces enabled the patient to place and remove the denture. [6]

Cheng et al. [18] described the maxillofacial prosthetic management of a patient with a midfacial defect complicated by post surgical microstomia. In their clinical report they have described the placement of endosseous implant tissue-bar retained over dentures with modified Prosthodontic procedures such as custom-made impression tray using putty type impression material which was manually dispensed intra-orally for primary impression and diagnostic cast thereafter. This prosthesis restored the patient's speech, dental articulation, mastication, lip support, esthetics and anterior oral seal. [18]

Jivanescu et al., [19] presented various clinical and technical steps involved in the fabrication of a flexible complete denture in case of a female patient with scleroderma induced microstomia. A standard tray was used. It was sectioned in the middle with a disc and two alginate sectorial impressions were taken. Afterwards, the palatine vault was marked with putty silicon. The preliminary impressions were aligned after which the first individual tray was made. The impression served to create a more adaptable individual tray of smaller sizes. The technical steps for the fabrication of the flexible complete denture were: Flasking and thermoplastic injecting. The flexible complete denture has a small flexibility degree but still allows insertion and removal with no difficulty into the oral cavity. [19]

 Other Methods of Management

Patient with microstomia may undergo surgical enlargement of oral aperture, but it has its own adverse effects that a scar may result. Without surgical intervention, it is very difficult to perform prosthetic treatment especially when the mouth circumference length is less than 160 mm square.

Conservative management of microstomia has been described in the literature and includes the use of microstomia orthoses to expand the oral opening. [2] Prosthetic rehabilitation of microstomia patients presents difficulties at all stages, from preliminary impressions to fabrication of prosthesis. [6] Limited mandibular opening can pose a major dental problem and the general difficulties of reduced access become even more apparent when providing prosthesis. The overall bulk and the height of impression trays make the recording of impressions exceptionally difficult if not impossible because the paths of insertion and removal of impressions are compromised by lack of clearance. The use of sectional impressions which may be recorded in two or more parts and then relocated outside the mouth is a useful technique to adopt for such patients. The trays can be provided with fins, pins, Lego pieces stepped or butt joints to facilitate relocations. [20] Use of flexible impression trays is another option.

Sectional and collapsible dentures are generally used to provide prosthodontic treatment to patients with limited intra-oral access. A swing-lock and/or simple hinge can be use to connect the two segments of such a collapsible dentures. [2] Some treatments include the use of Co-Cr frameworks with clasps to hold sectional complete denture, the use of a sectional complete dentures can also joined by a post that slides into stainless steel tubing. There are several commercially available magnetic attachment systems for use in clinical dentistry which can be used successfully for the treatment of patients with limited mouth opening. [12]


It is often difficult to apply conventional clinical procedures to construct dentures for patients who demonstrate limited mouth opening. However, with careful treatment planning and prudent designing, the use of either sectional impression techniques and/or sectional dentures many of the apparent clinical difficulties can be overcome. This article has reviewed various impression procedures and the prosthesis designs which aid in fabrication of prosthesis for a patient with the limited mouth opening which aids for a better function, health, esthetics and overall well being of the patient.


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