DENTAL TECHNIQUE

aAssociate PrbAssistant Pr

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Sectional collapsible complete removable dental prosthesis fora patient with microstomia

Potchaman Sinavarat, BSc, DDS, MSca and Chuchai Anunmana, DDS, MSc, PhDb

ABSTRACTPatients who have unusually small mouths may have difficulty in obtaining dental care andmaintaining good oral hygiene. The fabrication of conventional complete removable dental pros-theses for an edentulous patient with microstomia is challenging because of the limited access tothe oral cavity. Sectional collapsible complete removable dental prostheses were designed ashinged maxillary and mandibular complete dentures that can be folded for denture delivery. Thisdesign also prevented denture deflection during function by using the upper part of the prosthesis,minimizing the possibility of breakage. (J Prosthet Dent 2015;114:627-632)

Microstomia is a clinical con-dition affecting patients whohave very small mouths dueto orofacial cancer surgery,cleft lips, burns and traumaaround the oral cavity, scartissue after lip surgeries, or thecollagen group of diseases in-cluding submucous fibrosis

Figure 1. Patient with restricted oral opening. Intercommissural width atmaximum opening was approximately 32 mm.

and scleroderma.1-3 The oral manifestation of sclero-derma includes thin oral mucosa, xerostomia, limited jawopening, recurrent mouth sores, and dysphagia.Decreased salivary flow results in an increased caries rate,and removable dental prostheses can be problematic.4

Moreover, the intercommisural distance and oral aper-ture can be reduced as a result of the sclerosis of the facialskin. For most patients, this results in a maximumopening of less than 40 mm. Microstomia can be seen in80% of patients with systemic scleroderma. Women havea higher risk of the disease than men.5

Restricted oral opening can be a significant problemfor patients with microstomia when seeking dentaltreatment.6,7 Furthermore, contraction of the soft tissuearound the oral cavity makes it difficult to attainingdental care and perform good oral hygiene. As a result,these patients are prone to edentulism. Treatment op-tions include surgical correction to enlarge the mouth8

and dental implants,9 but if these options are not avail-able, sectional complete removable dental prostheses canbe an alternative treatment. Various pins, bolts, attach-ments, and Lego pieces have been used for the lockingmechanism.10-13 In some situations, joining the smallpieces of a sectional dental prosthesis intraorally may be

ofessor, Department of Prosthodontics, Faculty of Dentistry, Mahidol Univofessor, Department of Prosthodontics, Faculty of Dentistry, Mahidol Unive

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a problem because of poor manual dexterity. A castcobalt-chromium framework with a lingual hinge and aconventional swing lock has been designed as a treat-ment option.14,15

This dental technique report describes the prostho-dontic management of a 61-year-old edentulous man,whose oral opening was limited (intercommissural widthapproximately 32 mm) as a result of scleroderma (Fig. 1).Simple designs of maxillary and mandibular sectional

ersity, Bangkok, Thailand.rsity, Bangkok, Thailand.

627

Figure 2. Maxillary preliminary impression. A, Three sections of maxillary impression. B, Assembled impressions.

Figure 3. Sectional custom trays. A, Assembled maxillary tray. B, Stepped butt joint (arrow) prepared on left half of maxillary tray. C, Left and rightmandibular sectional trays. D, Stepped butt joint (arrow) prepared on left half of mandibular tray.

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edentulous custom-made trays were used to fabricatethe sectional collapsible complete removable dentalprostheses.

TECHNIQUE

1. Make the right and left preliminary maxillary im-pressions separately with modeling plasticimpression compound (Impression Compound;Kerr Corp). Trim each half of the impression 4 to 5mm away from the midline. Then reline each halfof the impression alternately with low-viscosity

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polyvinyl siloxane (Silagum; DMG Chemisch-Pharmazeutische Fabrik). Subsequently, adaptadditional modeling plastic impression compoundover the 2 halves to index the impression (Fig. 2).

2. Make a preliminary mandibular impression withpartial trays and irreversible hydrocolloid impres-sion material (Jeltrate; Dentsply Intl). The right andleft trays should cover the mandibular midline.

3. Fabricate a sectional custom maxillary tray from thepreliminary cast. Prepare a stepped butt joint alongthe midline of the sectioned tray; therefore, these 2parts are detachable (Fig. 3A, B). Fabricate the left

Sinavarat and Anunmana

Figure 5. Mandibular occlusion rim. A, Mandibular occlusion rim withcustom-made hinge located in middle of lingual base. B, Collapsedmandibular occlusion rim. C, Collapsed rim inserted in patient.

Figure 4. Maxillary occlusion rim. A, Custom-made hinge. B, Anterior andposterior segments of maxillary occlusion rim with custom-made hinge(arrow) at midline of posterior part. C, Folded posterior segment. D,Complete maxillary occlusion rim.

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Sinavarat and Anunmana

and right sectional custom mandibular traysseparately on each cast. Locate the anterior borderof the tray at the midline of the arch. Then positionthe left tray segment on the right cast and verifyproper alignment before preparing a stepped buttjoint (Fig. 3C, D).

4. Mold the border of each tray segment with a greenstick modeling plastic impression compound(Impression Compound; Kerr Corp). Make adefinitive impression on both segments of the archat the same time with low-viscosity polysulfide(Permlastic; Kerr Corp). Place the index over the 2parts to stabilize the trays. After the impressionmaterial has polymerized, remove the index first,and then flex the trays at the junction line and

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Figure 6. Finished complete removable dental prosthesis. A, Anterior segment and posterior foldable segment of maxillary denture. B, Assembledmaxillary denture. C, Foldable mandibular denture with Co-Cr lingual plate. D, Assembled mandibular denture.

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subsequently remove the tray segments one byone. Finally, pour the impressions with Type IVdental stone (Vel-Mix; Kerr Corp).

5. Prepare the maxillary record base in 2 pieces as theposterior and the anterior segments. Place acustom-made hinge at the midline at 5 mm ante-rior to the posterior border of the base. Separatethe posterior baseplate into left and right sections;therefore, it is foldable. Fabricate the anteriorsegment and place it over the posterior segment tostabilize the posterior base. Make an occlusion rim(Fig. 4). Fabricate the mandibular record base in1 piece. Incorporate a custom-made hinge at themidline of the lingual base and section the baseat the midline into left and right parts. The base isnow collapsible in the horizontal plane (Fig. 5).

6. Record the maxillomandibular relationship incentric relation and mount the definitive casts on asemiadjustable articulator (Hanau H2; Whip MixCorp).

7. Arrange the nonanatomic artificial teeth (MajorDent; Major Prodotti Dentari) with posteriorbalancing ramps to obtain eccentric balanced oc-clusion. At the trial stage, verify the occlusion,speech function, and esthetics.

8. Make a cast cobalt-chromium lingual plate byreducing the wax on the lingual surface of the

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mandibular trial denture. This lingual plate rests onthe occlusal surfaces of the second premolars andthe first molars and helps stabilize the left and rightsegments during function.

9. To attach the anterior segment to the posteriorsegment of the maxillary denture base, place 2 ballattachments on the posterior base segment with adental surveyor to obtain parallel paths of insertionon both sides. Adhere 2 ball caps or the femaleparts on the tissue surface of the anterior denturebase with autopolymerized acrylic resin (Takilon;Salmoiraghi Produzione Dentaria). Then finish andpolish the complete removable dental prosthesis(Fig. 6).

10. At the delivery appointment, evaluate the denturebase extension, relieve excessive pressure of theintaglio surface, and adjust the occlusion to derivesimultaneous tooth contact in centric and eccentricposition. Instruct the patient to operate the den-ture assembly, and emphasize oral and denturehygiene. Figure 7 shows the prosthesis in the oralcavity.

DISCUSSION

Although the cast cobalt-chromium swing lock dentureswith lingual hinge as described by Wahle et al14 and

Sinavarat and Anunmana

Figure 7. Complete removable dental prosthesis in patient’s mouth. A, Maxillary prosthesis. B, Mandibular prosthesis. C, Complete removable dentalprosthesis in occlusion. D, Frontal view.

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Rathi et al15 were easily delivered, they were more costlythan this design because of the sophisticated laboratorywork required. This design also prevented denturedeflection and possible breakage. In addition, retentionand stability were achieved during mastication. However,because the denture base is made of acrylic resin, regularmaintenance is required to maintain the function andintegrity of the dentures. Oral exercises and mouthstretching as recommended by Naylor and Manor16

were suggested to maintain the oral aperture andenhance the flexibility of the facial skin. This was to avoidfurther fibrosis, which could make dental treatmentimpossible.

SUMMARY

By using palatal and lingual midline hinges together withthe ball attachment and lingual plate, the sectionalcollapsible complete removable dental prosthesis waseasily inserted, and the prosthesis also provided adequate

Sinavarat and Anunmana

function for the patient. The limitations of the treatmentprocedure and the need for continuous maintenancemust be emphasized to the patient to avoid tissue ul-ceration and further fibrosis.

REFERENCES

1. Garnett MJ, Nohl FS, Barclay SC. Management of patients with reduced oralapertureand mandibular hypomobility (trismus) and implications for opera-tive dentistry. Br Dent J 2008;204:125-31.

2. Howe GL. Disorders of the masticatory apparatus. Br Dent J 1983;155:405-11.3. Ward-Booth P, Eppley BL, Schmelzheisen R. Maxillofacial trauma and

esthetic facial reconstruction. London: Churchill Livingstone; 2003.4. Chaffee NR. CREST syndrome: clinical manifestations and dental manage-

ment. J Prosthodont 1998;7:155-60.5. Spackman GK. Scleroderma: what the general dentist should know. Gen

Dent 1999;47:576-9.6. Heasman PA, Thomason JM, Robinson JG. The provision of prostheses for

patients with severe limitation in opening of the mouth. Br Dent J 1994;176:171-4.

7. Meraw SJ, Reeve CM. Dental considerations and treatment of theoncology patient receiving radiation therapy. J AmDent Assoc 1998;129:201-5.

8. Lopez J Jr. Surgical management of microstomia in the dental office. J AmDent Assoc 1978;97:840-2.

9. Haas SE. Implant-supported, long-span fixed partial denture for a sclero-derma patient: a clinical report. J Prosthet Dent 2002;87:136-9.

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10. Al-Hadi LA, Abbas H. Treatment of an edentulous patient with surgicallyinduced microstomia: a clinical report. J Prosthet Dent 2002;87:423-6.

11. Benetti R, Zupi A, Toffanin A. Prosthetic rehabilitation for a patient withmicrostomia: a clinical report. J Prosthet Dent 2004;92:322-7.

12. Conroy B, Reitzik M. Prosthetic restoration in microstomia. J Prosthet Dent1971;26:324-7.

13. McCord JF, Tyson KW, Blair IS. A sectional complete denture for a patientwith microstomia. J Prosthet Dent 1989;61:645-7.

14. Wahle JJ, Gardner LK, Fiebiger M. The mandibular swing-lock completedenture for patients with microstomia. J Prosthet Dent 1992;68:523-7.

15. Rathi N, Heshmati R, Yilmaz B, Wilson W. A technique for fabricating ahinged mandibular complete dental prosthesis with swing lock for a patientwith microstomia. J Prosthet Dent 2013;110:540-3.

16. Naylor WP, Manor RC. Fabrication of a flexible prosthesis for the edentulousscleroderma patient with microstomia. J Prosthet Dent 1983;50:536-8.

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Corresponding author:Dr Chuchai AnunmanaMahidol UniversityDepartment of Prosthodontics6 Yothee Rd, RajtheviBangkok, 10400THAILANDEmail: chuchai.anu@mahidol.edu

AcknowledgmentsThe authors thank Sutas Jitchuen and Manit Choetkiertikul for their technicalsupport and laboratory work.

Copyright © 2015 by the Editorial Council for The Journal of Prosthetic Dentistry.

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