Samuel J. McKenna

Mandibular reconstruction using computer-aided design and computer-aided manufacturing: an analysis of surgical results.

PURPOSE The purpose of this study was to analyze the accuracy of virtual surgical planning in mandibular reconstruction. MATERIALS AND METHODS This is a retrospective study involving 8 consecutive patients reconstructed with nonvascularized iliac crest bone grafts and free fibula osteomyocutaneous flaps. DICOM data from a maxillofacial skeleton computed tomography (CT) scan were sent to a medical modeling company and used to map the mandibular resection, anatomically place the mandibular reconstruction plate, and create surgical guides. After surgery a postoperative CT compared the virtual plan to the surgical result. Linear measurements [2 transverse and 1 anterior-posterior (A-P)] were performed to determine if the virtual surgical result was achieved. The transverse measurements were made from the condylar head to condylar head and from the gonial angle to gonial angle. The A-P analysis was made by measuring a perpendicular line drawn from the anterior inferior mandibular border to the center point on the condylar head to condylar head measurement. RESULTS The average surgical error in the A-P dimension for the iliac crest bone grafts and free fibula flap was 0.2 mm (range 0.0 mm to 0.7 mm) and 0.9 mm (range 0.2 mm to 1.9 mm), respectively. In the transverse dimension the average surgical error was 1.6 mm (range 0.7 mm to 2.4 mm) and 2.7 mm (range 1.9 mm to 4.5 mm) from condyle to condyle, and 1.7 mm (range 0.7 mm to 2.7 mm) and 2.5 mm (range 0.4 to 4.8 mm) from gonial angle to gonial angle. CONCLUSION The use of CAD-CAM (Medical Modeling, Golden, Colorado) technology for the fabrication of surgical resection guides and mandibular reconstruction plates resulted in an accurate surgical result.

Modified condylotomy for treatment of the painful temporomandibular joint with a reducing disc

Data from a pool of approximately 400 patients operated on with modified condylotomy during a 9-year period are presented. The chief findings were good relief of pain and dysfunction, and reversal of the internal derangement in a high percentage of patients. There was low morbidity and remarkably few complications. Comparison of these findings with published results of alternative surgical and nonsurgical procedures seems to favor modified condylotomy.

Use of porous hydroxylapatite blocks for augmentation of atrophic mandibles

A clinical study of the use of porous blocks of hydroxylapatite (Interpore 200) for augmentation of atrophic residual mandibular ridges was performed. Fifteen patients each had three preoperatively customized blocks placed. They were then examined clinically and radiographically for at least 2 years. Six patients had skin-graft vestibuloplasties performed over the blocks 3 months after implantation; dentures were made for 11 of the patients. No clinical or radiographic evidence of migration or resorption of the blocks was found; however, all 15 patients suffered complications. Eleven developed ulcerations over the blocks with persistent exposure, six had suture line dehiscence leading to exposure, two infections occurred, and two patients developed chronic pain in the area of block insertion. The skin graft took only partially in all patients undergoing subsequent vestibuloplasties. To date, 37 of the original 45 blocks have required complete removal. Histologic examination of removed blocks has revealed partial filling of the pores with lamellar bone. The use of blocks of porous hydroxylapatite to reconstruct atrophic residual mandibular ridges was found to have an unacceptably high rate of failure and the ability to sustain an overlying split-thickness skin graft was unpredictable.

Macrognathia of renal osteodystrophy in dialysis patients

A multiinstitutional study of macrognathia secondary to renal osteodystrophy in dialysis patients is presented. The nine cases reviewed reveal a variety of radiographic and histopathologic features, some of which resemble fibrous dysplasia and others suggestive of Pagets disease of bone. This article contains diagnostic criteria for differentiating renal osteodystrophy from similar fibro-osseous proliferations along with a discussion of the underlying cause and appropriate therapeutic interventions.

Delayed management of a mandibular vascular malformation

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Long-term follow-up of modified condylotomy for internal derangement of the temporomandibular joint.

OBJECTIVES The purpose of this study was to evaluate disk position and patient response 10 years after modified condylotomy for symptomatic reducing disk displacement. STUDY DESIGNS Questionnaires and invitations to return for examination and temporomandibular joint magnetic resonance imaging were mailed to 39 consecutive patients 10 years after modified condylotomy. RESULTS On a 10-point scale the mean pain experienced by the 17 respondents (27 joints) to the questionnaire was 2.0. Ninety percent of 20 joints (12 patients) examined were free of tenderness to palpation. Magnetic resonance imaging in 10 patients (17 joints) showed disk reduction in 59%, displacement with reduction in 29%, and displacement without reduction in 12%. Eighty-five percent of the joints met American Association of Oral and Maxillofacial surgeons criteria for a successful therapeutic outcome. CONCLUSIONS The study suggests a role for modified condylotomy in the long-term management of symptoms associated with reducing disk displacement. Further, modified condylotomy can frequently reverse an internal derangement and seems to protect against the natural progression of osteoarthrosis.

Soft tissue and bony enlargement of the mandible in an infant

An 8-week, full-term infant, with an uncomplicated delivery, presented to Childrens’ Mercy Hospital with a 3-day history of fever, irritability, and constipation. The mother had noted swelling over the right mandible and became concerned. On admission to the hospital, it was noted that the child was lethargic, but did not appear to be in any pain. The rectal temperature was lOl”F, the white blood cell count was 21,4OO/pL, hemoglobin was 10.6 g, the platelet count was 1.1 million, the sedimentation rate was 62 mm/h, and alkaline phosphatase was 466 IU. Radiographs revealed soft tissue enlargement over the right mandible, which was also enlarged (Fig 1). Periosteal enlargement of the right ribs and a pleural effusion were also noted (Fig 2). There was no involvement of the ulna or tibia. A growth chart comparison revealed a substantial drop from the 50th percentile to the 5th percentile, with no reported change in diet or stools.

Intraoral Vertical Ramus Osteotomy Procedure and Technique

Intraoral vertical ramus osteotomy is a useful osteotomy for mandibular setback and rotational movements of the mandible. The correct placement of the osteotomy is critical to the preservation of proximal segment muscle attachments. Preservation of adequate proximal segment medial pterygoid attachment is necessary to prevent condylar sag. Intraoral vertical ramus osteotomy has a low incidence of neurosensory dysfunction. Intraoral vertical ramus osteotomy avoids unfavorable condylar loading and may simultaneously address skeletal malocclusion and temporomandibular joint symptoms.

Biologic basis for modified condylotomy in the management of temporomandibular joint degenerative diseases

The biologic basis for treating temporomandibular joint internal derangement with modified condylotomy rests in the ability of this procedure to improve or normalize disc position and favorably alter the course of osteoarthrosis and internal derangement. Data presented here favor modified condylotomy over other disc-preserving treatments for temporomandibular joint internal derangement.