Reservoir Complete Denture in a Patient with Xerostomia Secondary to Radiotherapy for Oral Carcinoma: A Case Report and Review of Literature
A 67-year-old male patient reported to the Department of Prosthodontics with the chief complaint of difficulty in mastication due to dryness of mouth and absence of teeth. Medical history revealed that the patient had undergone RT 2 years back for the moderately differentiated squamous cell carcinoma involving posterior 1/3rd of left lateral border of the tongue.\nExtraoral examination revealed reduced lower facial height and unsupported lips. Intraoral examination revealed maxillary and mandibular edentulous residual ridges and decreased salivary flow [Figure and ]. A diagnosis of xerostomia secondary to RT was made after calculating unstimulated whole saliva flow rate by absorbent (swab) method (whole saliva flow rate was < 0.1 ml/min).\nTreatment plan included either (1) fabrication of implant supported or conventional upper and lower complete dentures with external application of salivary substitute in the oral cavity or (2) fabrication of lower complete denture with artificial saliva reservoir in it and upper conventional complete denture. It was discussed with the patient and informed consent was obtained for the agreed treatment, which included rehabilitation of the upper arch with conventional complete denture and reservoir denture in the lower arch.\nPrimary impressions were recorded in irreversible hydrocolloid impression material. After border molding, final impressions were made in medium body elastomeric impression material [Figure and ] Jaw relation was recorded with wax occlusal rims fabricated on self-cure acrylic denture base. The vertical height of the lower rim was measured. Accordingly, teeth selection was carried out and size of the reservoir was determined, so that maximum space for the reservoir is gained while maintaining 2 mm thickness of the reservoir wall. Then using face bow, only upper cast was mounted on the semi-adjustable articulator. Upper and lower wax rims with the centric records were preserved and set aside for later use Shellac base plate was adapted on the lower final cast. According to the predetermined dimensions, putty type of elastomeric material was placed in the center of the base plate and modeling wax (modeling wax, DPI, Mumbai, India) was added at the periphery to create the walls of the reservoir []. Space for reservoir was created by removing putty from the center []. Five stainless steel rods (3 mm in length and 2 mm in diameter) were positioned parallel to each other in the wax []. The two parts of the reservoir lower denture would be attached to each other using these rods. A bevel was carved 1-1.5 mm above the inferior border at the periphery of the base Then flasking and dewaxing was carried out as a routine procedure. Clear heat cure polymerized resin was used for packing the mold space (Trevalon HI, Dentsply India Ltd., Gurgaon, India) and after curing a permanent clear acrylic base was obtained with five stainless steel rods embedded in it and having a reservoir in the center. Thus, the tissue bearing plate of the two piece reservoir denture was fabricated [] Next, the lower cast was retrieved from the flask and with the preserved wax occlusal records it was mounted on the semi-adjustable articulator. After this, the lower temporary record base was replaced with the permanent clear acrylic base [] Teeth arrangement was carried out on the semi-adjustable articulator with putty maintaining the reservoir space []. Extra bulk of wax was added to the mandibular trial denture to gain optimum thickness. Then trial dentures were finished and tried in the patient's mouth to check for retention, stability, esthetics, phonetics and comfort [] Flasking followed by dewaxing of the lower trial denture was carried out to obtain base portion of the flask containing permanent denture base [] and a counter portion containing the teeth [] Aluminum foil was adapted on the denture base for easy separation of the two halves of the mandibular denture []. Packing was carried out with pink heat cure acrylic resin (Trevalon HI, Dentsply India Ltd., Gurgaon, India) and processed to obtain the teeth bearing plate of the reservoir denture [] After careful deflasking aluminum foil was removed. The teeth bearing plate of the mandibular denture rested on the bevel created on the tissue bearing plate. Finishing and polishing was carried out with the segments together to ensure a flush smooth finish, without any damage to the edges [] Two outlet holes were drilled for the salivary substitute on each side in the retromylohyoid region of the teeth bearing plate and were adjusted in size similar to the thickness of a 23 gauge orthodontic wire [] Artificial saliva substitute (Wet mouth, ICPA Health Products Ltd., India) was then filled in the reservoir space of the lower denture with a capacity of 3.8 ml The upper denture was fabricated in the conventional manner Denture insertion was carried out and post-insertion instructions were given to the patient. Furthermore, he was taught how to open and close the reservoir denture for filling the artificial salivary substitute and cleaning the reservoir space. In addition, fine orthodontic wire was provided to him for cleaning the drainage holes if they get blocked Recall appointments were scheduled after 24 h, 1 week, 4 weeks and every 6 months. At recall appointments, good retention was observed and relief from the symptoms of dry mouth and improvement in dietary intake was reported by patient. Patient found it easy to clean the dentures as taught and informed that once filled saliva substitute lasts for 4-5 h. Patient has now been successfully wearing the dentures for over 2 years.