Hyoid Displacement During Swallowing Function for Completely Edentulous Subjects Rehabilitated With Mandibular Implant Retained Overdenture

New conventional complete denture with optimal flange extension and well established lingualized balanced occlusal scheme was constructed for every patient. To construct the radiographic stent, clear acrylic resin duplicate for the mandibular denture was constructed, several small holes were made on the polished surface of the duplicate. These holes were filled with radio-opaque gutta-percha points to act as a reference points during determination of the quantity of available bone for implant placement and for construction of stereolithographic surgical guide.

Cone beam computerized tomography [i-CAT] was used to construct the stereolithographic surgical guide by applying dual scan technique. By using the surgical guide, two dental implants (Dentium implants, 12-14mm in length, 3.6-4mm in diameter, Superline II) were placed in the canine regions of the mandibular arch with guided surgical protocol. The patients were instructed to take prophylactic antibiotic two times a day (875mg Amoxicillin and 125mg Clavulanic acid) 24 hours before the surgery and continue after the surgery for seven days. Non-steroidal anti-inflammatory drug was used to control the pain.

After surgery, the complete denture was withdrawn, and the patient was instructed to eat soft diet. After one week, the mandibular denture was relieved and relined with Cold- curing silicon based relining material (Softliner, PROMEDICA). The dentures were delivered to the patients and follow up visits were scheduled. After three to four months, the dental implants were exposed, and the healing abutments were secured to the dental implants. After healing of the soft tissue (7-10 days), the healing abutments were removed, and ball attachments (Dentium ball abutment, Superline II) were screwed to the dental implants. Direct pick-up technique was used to incorporate the housing of the attachments into the fitting surface of the mandibular denture using self-cured acrylic resin material. The occlusion of the overdenture was evaluated to eliminate any premature occlusal contact then the overdenture was delivered to the patient.

Videofluroscopic swallowing study (VFSS):

All subjects were examined by using videofluroscopic swallowing study to evaluate bolus movements. This evaluation was done at three different oral conditions, without complete denture (WCD), after 2 months of conventional complete dentures insertion (CDs), and after 2 months of implant overdenture insertion (IODs). Each patient was instructed to swallow 10 ml of thin liquid {20% barium sulfate (Prontobario H.D®) and 80% water} three times. The records of the videofluroscopic swallowing evaluation were saved to the computer for later analysis. A software Program (EO Program) was used to placing timing on the frame of the video (1/100 second) and analyze the recording by frame by frame data analysis.