a maximum mouth opening that is smaller than the size of a complete denture can make prosthetic treatment challenging .
this article describes a simple technique used to fabricate maxillary and mandibular custom sectional impression trays for making definitive impressions in patients with microstomia .
microstomia is defined as an abnormally small oral orifice.1 this disorder is described as a reduction in the oral aperture size associated with facial burns , diffuse scleroderma , traumatic injuries , and surgical reconstruction involving the orbicularis oris muscle .
microstomia can result in multiple debilitating sequelae such as inability to masticate , droolin g , speech problems due to poor articulation , impaired delivery of oral hygiene and dental care , and psychological problems secondary to facial disfigurement.28 several methods of prosthodontic treatment for microstomia patients have been presented , and numerous devices to expand the oral commissure have been described.3,912 the prosthetic rehabilitation of microstomia patients presents difficulties at all stages , from preliminary impressions to prosthesis fabrication.13 because such patients have small oral openings , using conventional methods for making definitive dental impressions and fabricating dentures may be extremely difficult .
making the accurate impressions represents the initial difficulty in the prosthetic rehabilitation of such patients .
the recommended techniques for obtaining preliminary impressions for microstomia patients include the use of modeling plastic impression compound , the use of stock impression trays with heavy and light body silicone impression materials , and flexible impression trays with silicone putty .
the casts obtained from these preliminary impressions are then used for making custom sectional impression trays .
these trays typically consist of 2 locking devices or assemblies , 1 situated anteriorly and the other posteriorly , which join and provide stability to both the sections of the trays .
after the definitive impressions are made , these trays are reassembled extraorally and are poured in dental stone to obtain definitive , working casts .
several studies have described various techniques that are used for making custom sectional impression trays.1418 different devices used for connecting the custom sectional trays include hinges,14 plastic building blocks ( lego ; lego systems inc , enfield , conn .
, usa),15,16 orthodontic expansion screws,17 or locking levers.18 this article describes a simple , cost - effective , and time - saving method for fabricating custom sectional impression trays using easily available dual die - pins and sleeves as potential devices for interlocking the sectional trays .
the locking mechanism design includes an anterior locking assembly for the maxillary and mandibular custom trays and a posterior locking assembly for only the maxillary custom tray .
by using the conventional method , fabricate the maxillary and mandibular custom sectional impression trays by using autopolymerizing acrylic resin ( dpi - rr , dental products of india , mumbai , india ) on the preliminary casts .
make the handles of the trays ( minimum dimensions with 13 mm height , 10 mm length , and 10 mm width ) such that they incorporate the metal sleeves of the dual die - pins ( m.r .
section both the custom impression trays at the midline by using a diamond disk ( dfs , germany ) .
steps in the fabrication of the anterior lock assembly in the maxillary and mandibular custom sectional impression trays : - the assembly basically consists of 2 dual die - pins and 2 sleeves .
closely juxtapose the 2 sleeves such that the smaller keyway of 1 sleeve faces the larger keyway of the other sleeve .
join these sleeves by inserting the 2 dual die - pins and making the assembly a rigid joint ( figure 1a  d ) .
- make a slot on the inside portion of the handles on each half of the sectioned custom trays to incorporate the sleeve ( figure 2a & b ) .
- attach the sleeves in the slots by using the autopolymerizing acrylic resin as mentioned previously ( figure 3 ) .
- verify the position of the attached sleeves by inserting die - pins such that the halves juxtapose precisely in both the sectioned trays . -
fabricate an anterior assembly for the mandibular sectional tray in a similar manner ( figure 7 ) .
steps in the fabrication of the posterior lock assembly in the maxillary custom sectional tray : - cut the 2 dual die - pins that are attached to sleeves halfway through their heights ( figure 4 ) by using a carborundum disk ( dentorium , new york , usa ) .
only the broader upper halves are used for fabricating the posterior assembly and the lower halves are discarded .
- attach the half - cut sleeves on the posterior parts of the sectioned custom tray halves using acrylic resin such that the greatest dimension of each sleeve is oriented in the anteroposterior direction .
check for parallelism between the sleeves using a dental surveyor and verify the fit of the die - pins in the respective sleeves ( figure 5 ) . -
fabricate an acrylic resin block ( 6 mm height , 10 mm width , and 4 mm longer than the distance between the 2 attached sleeves ) using the autopolymerizing acrylic resin ( figure 4 ) . - transfer the respective points of the half - cut die - pin heads on the acrylic bar by using a pressure spot indicator ( coltene psi , switzerland ) and drill slightly oversized holes in the acrylic bar on the marked points by using a bur ( 261-ef023 , brasseler , usa )
- with the closely juxtaposed sectioned trays and the die - pins of the anterior assembly placed in position , secure the heads of the half - cut die - pins into the holes by using the autopolymerizing acrylic resin ( figure 5 & figure 6 ) .
the 2-piece custom - made tray described above allows for a functional impression to be made despite the difficulties associated with microstomia .
the anterior locking assembly described in this article does not require any special alteration in the conventional custom tray design .
the die - pins with metal sleeves used in this technique provide a greater degree of stability and a precise union of the 2 sections of the tray .
the joint can be made more rigid by activating the 2 prongs of each dual die - pin away from each other .
this technique used for fabricating custom sectional impression trays does not require any special devices or complex locking joints .
the only additional materials used are the dual die - pins which are commercially available at a minimum cost .
it is often difficult to use conventional methods for fabricating dentures for patients with limited mouth opening .
this article described a simple , time - saving , and cost - effective method used to fabricate custom sectional impression trays for making definitive impressions in patients with microstomia .
 objective : a maximum mouth opening that is smaller than the size of a complete denture can make prosthetic treatment challenging . 
 this article describes a simple technique used to fabricate maxillary and mandibular custom sectional impression trays for making definitive impressions in patients with microstomia . 