Written by Brendan W. Tully, DDS, MBA Monday, 16 July 2012 13:10
As Operation Iraqi Freedom (OIF) and Operation Enduring Freedom enter their eighth and tenth years respectively, improvised explosive devices (IEDs) continue to kill and maim US service members on a regular basis. Despite adherence to a strict protocol of protective equipment including Kevlar helmets, throat guards, and ballistic goggles, the oral-facial complex is still very vulnerable in the modern day combat environments of Iraq and Afghanistan. Dentoalveolar injuries sustained from IEDs will continue to present significant challenges for both the civilian and military comprehensive dentist.
A 32-year-old male US Army staff sergeant was patrolling in an armored Bradley fighting vehicle in the area of Balad, Iraq, in 2007 in support of OIF when an IED exploded underneath his vehicle. According to witnesses, the force of the blast lifted the 25-ton vehicle off of the ground and knocked the patient unconscious for a period of 20 minutes. The patient, who was wearing ballistic goggles, sustained numerous shrapnel wounds to the face and was bleeding profusely before Army medics were able to stabilize him. The patient’s left mandible (midbody) was fractured in the explosion (Figure 1) and upon regaining consciousness, he reported “spitting out teeth” as a result of numerous enamel fractures sustained primarily in the anterior and posterior maxilla (Figures 2 and 3).
|Figure 1. Panoramic radiograph (PANOREX) of patient shortly after he arrived from Iraq.||Figure 2. Preoperative photo of patient open.|
|Figure 3. Preoperative photo of maxilla.||Figure 4. Patient receiving the Purple Heart from his commanding officer.|
The patient was medically evacuated to Camp Anaconda in Balad, where US Army oral surgeons completed open reduction internal fixation on the patient’s left mandible. In addition to his oral-facial wounds, the patient also sustained a moderate traumatic brain injury and an IED-related injury to his left foot. The patient was transferred to a US Army hospital in Lanstuhl, Germany, and then eventually back to the United States (Figure 4).
Upon return to the First Cavalry Division at Fort Hood, Tex, the patient reported to the Billy Johnson Dental Clinic, home to one of the US Army’s three 2-year comprehensive dentistry residency programs. Fort Hood is one of the largest military installations in the United States and is home to America’s Armored Corps, including the Third Armored Cavalry Regiment, the First Cavalry Division, and the Fourth Infantry Division. One in 10 active duty US soldiers is stationed at Fort Hood.1
Diagnosis and Treatment Planning
The patient’s chief request was to “save as many teeth as possible.” After a thorough exam and a complete diagnostic evaluation, including periodontal probing and hygiene prophylaxis, the soldier was accepted as a patient in the residency, and work began immediately in the preparatory/hygienic/diagnostic/disease control phase of the Anderson Medical Model.2 The patient had adequate oral hygiene, was not in pain, and reported no allergies or tobacco use. Clinical probing depths of 4 mm were noted on only 3 tooth surfaces and tooth No. 26 had asymptomatic localized Miller Class III recession (Figure 5). The patient was taking Midrin for migraine headaches and amitriptyline, a tricyclic antidepressant, also for the treatment of migraine headaches.
|Figure 5. Preoperative photo of patient closed.||Figure 6. Postoperative photo of maxilla.|
|Figure 7. Master cast of the patient’s maxilla with locators.||Figure 8. Denture caps.|
Because the patient wanted to save as many teeth as possible, the decision was made to proceed with both an implant and tooth-retained maxillary removable partial denture after extracting those teeth determined to be nonrestorable or unfavorable as long-term overdenture abutments.
Teeth Nos. 4, 5, 8, 9, 10, 12, and 13 were extracted, and a temporary transitional partial was delivered. Because of its history of multiple restorations and Class 1 mobility, tooth No. 10 was determined to be a poor long-term overdenture abutment and it was extracted, leaving tooth No. 11 as the only remaining anterior tooth to serve as an overdenture abutment. Crown lengthening on tooth No. 3 was also accomplished at the time of the maxillary extractions.
The Anderson Medical Model requires a re-evaluation phase to assess the patient’s oral hygiene status before progressing to the corrective restorative phase of the comprehensive treatment. The patient demonstrated a marked improvement in his oral hygiene and work continued to restore the patient’s remaining dentition.
In the corrective restorative phase, elective endodontics was performed on tooth No. 11, a post space was created, and a locator root attachment, also referred to as a locator abutment for natural teeth (Zest Anchors) was cemented with a self-curing resin cement (Panavia [Kuraray America]).
Although canines have traditionally been used as overdenture abutments, their prominent bony eminence can complicate the aesthetic contours of removable prostheses. The prominent canine eminence can also contribute to tissue undercut problems, making it difficult for patients to place and remove their prostheses. With the use of lateral incisors as overdenture abutments, tissue undercut problems are usually avoided and favorable aesthetic results are readily attained.3
An endosseous implant and a 4-mm healing abutment (Replace Select 4.3 mm x 10 mm [Nobel Biocare]) was placed in the area of tooth No. 7, and the patient’s transitional partial was relieved in order to avoid immediately loading the implant. A survey PFM crown with a mesial rest was cemented with a resin cement (RelyX Unicem [3M ESPE]) on tooth No. 3 (Figure 6), and a vinyl polysiloxane impression (Aquasil Ultra Heavy Smart Wetting Impression Material and Aquasil Ultra XLV Smart Wetting Impression Material [DENTSPLY Caulk]) was taken and subsequently poured up with locator analogs (Figure 7). The master cast was fitted with 2 denture caps—one on the implant in the area of tooth No. 7 and one denture cap on tooth No. 11 (Figures 8 and 9). This allowed the Kennedy Class IV removable partial denture (RPD) to be fabricated with the denture caps incorporated into the initial processing, thus avoiding the procedure of “picking up” the locator abutments and retro-fitting the RPD (Figure 10).
|Figure 9. Master cast with removable partial denture (RPD) framework.||Figure 10. Completed RPD. Note denture caps with black inserts.|
|Figure 11. Preoperative full-facial photo.||Figure 12. Postoperative facial view of patient.|
While it is not unusual to have both a combined natural tooth and an implant-retained prosthesis, the issue of attaining maximum parallelism between the locator attachments is critical. Most implant overdenture abutments require parallelism within approximately 10° to function properly.4 Parallelism of the retentive abutments allows for: (1) consistent and uniform fit of the prosthesis, (2) an unobstructed path of prosthesis insertion and removal, and (3) less wear on the retentive elements. Nonparallel abutments may compromise the structural integrity, aesthetics, and function of the prosthesis and may only be remedied with surgical re-treatment or prosthetic compensation in the form of an altered design of the final prosthesis.5
Various levels of prosthetic retention can be achieved with the color-coded replacement male inserts that correspond to different levels of retentive force. After trying several different colors, the patient was most comfortable with the blue replacement male inserts (1.5 lbs of retentive force) and later reported that he had no fear of losing his prosthesis during mastication.
In the mandible, the patient complained that tooth No. 26, in extreme lingual version, was a constant irritant to his tongue and it was subsequently extracted. Tooth No. 30 was diagnosed with a necrotic pulp and asymptomatic apical periodontitis. Nonsurgical root canal therapy was performed on tooth No. 30 followed by a PFM crown. A Class I occlusal amalgam was placed on tooth No. 28 followed by a distal occlusal amalgam on tooth No. 29. Previous studies by the Dutch research group of Käyser and Nijmegen6 found that shortened dental arches comprised of anterior and premolar teeth generally fulfilled the requirements of a functional dentition.6 For this reason, and the close proximity of the screw and plate to tooth No. 20 on the patient’s left mandible, an endosseous implant to attain first molar occlusion was not attempted.
As a result of the IED explosion, the patient suffered from short-term memory loss and was unable to remember everyday schedules and appointments without the assistance of a US Army-provided Palm Pilot. The patient was also experiencing severe migraine headaches that became progressively worse with physical activity. After extensive neurological testing and physical therapy, it was determined that the patient was unable to perform his role as a front line soldier and the Army elected to medically retire the patient.
As of the submission of this article, the patient is currently awaiting a medical retirement board and release from active duty (Figures 11 and 12).
- US Army. The Official Website of Fort Hood, Texas. pao.hood.army.mil. Accessed January 14, 2012.
- Anderson MH, Molvar MP, Powell LV. Treating dental caries as an infectious disease. Oper Dent. 1991;16:21-28.
- Nelson DR, von Gonten AS. Biomechanical and esthetic considerations for maxillary anterior overdenture abutment selection. J Prosthet Dent. 1994;72:133-136.
- Dario LJ. A maxillary implant overdenture that utilizes angle-correcting abutments. J Prosthodont. 2002;11:41-45.
- Shor A, Shor K, Goto Y. Implant-retained overdenture design for the malpositioned mandibular implants. Compend Contin Educ Dent. 2006;27:411-421.
- Kanno T, Carlsson GE. A review of the shortened dental arch concept focusing on the work by the Käyser/ Nijmegen group. J Oral Rehabil. 2006;33:850-862.
Disclosure: Dr. Tully reports no disclosures.
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