Faculty Bibliography

PURPOSE: The objective of the present study was to evaluate the biomechanical fixation and bone-to-implant contact (BIC) of plateau root form implants of varied surfaces. MATERIALS AND METHODS: Plateau root form implants, 3.5 mm in diameter, 8 mm in length, with 4 surfaces (n = 16 each)--machined, alumina-blasted/acid-etched, alumina-blasted/acid-etched plus nanothickness bioceramic coating, and plasma-sprayed calcium-phosphate--were used. They were bilaterally placed at the distal femur of 16 New Zealand rabbits and remained in place for 2 and 4 weeks in vivo. After euthanizing the rabbits, the implants were subjected to torque to interface fracture and were subsequently processed as nondecalcified approximately 30-microm-thickness slides for histomorphologic analysis and BIC determination. Statistical analysis was performed using analysis of variance at the 95% level of significance, considering implantation time and implant surface as independent variables and the torque-to-interface fracture and BIC as dependent variables. RESULTS: The torque-to-interface fracture was significantly affected by the implant surface (P < .001) but was not affected by the implantation time (P > .20). The implantation time and implant surface had significant effects on the BIC (P < .04 and P < .001, respectively). The greatest torque-to-interface fracture and BIC was observed for the plasma-sprayed calcium-phosphate. CONCLUSION: The implant surface significantly influenced early bone healing around plateau root form implants.

Metallic ion release has raised concerns for the utilization of titanium and titanium alloys in implant dentistry. As an alternative, yttriastabilized tetragonal zirconia (Y-TZP) has been considered the material of choice due to its favorable biological and mechanical properties. Zirconia has been shown both in vitro and in vivo experiments to exhibit desirable osseointegration, cell metabolism, and soft tissue response. According to the mechanical testing of unaged Y-TZP onepiece implants, catastrophic failure of ceramic implants in anterior esthetic regions is unlikely. The utilization of a one-piece Y-TZP implant might be an option to fulfill the esthetic and mechanical needs in oral implant treatments when esthetics is the major concern.

PURPOSE: Perineural invasion (PNI) in oral squamous cell carcinoma (SCC) is recognized as a significant predictor of outcome. PNI is associated with locoregional recurrence and decreased survival of patients with head and neck SCC. Nerve growth factor (NGF) has been shown to be involved in PNI in several malignancies, including breast, prostate, and pancreatic cancers. We investigated the hypothesis that NGF and its high-affinity receptor tyrosine kinase A (TrkA) are highly expressed in cases of oral SCC that have histologic evidence of PNI. MATERIALS AND METHODS: We performed immunohistochemistry on archived oral tongue SCC specimens from the established oral and general pathology databases at the University of California, San Francisco. The following groups were evaluated: 1) 21 T1/T2 oral tongue SCC cases with PNI and 2) 21 T1/T2 oral tongue SCC cases without histologic evidence of PNI. RESULTS: Strong homogeneous cytoplasmic staining for NGF and TrkA was detected in the malignant cells in the PNI-positive group of tumors. In group II (PNI negative) NGF and TrkA were detected in the stroma cells or were very weakly expressed by the malignant cells. We were able to show the presence of NGF and TrkA in the cytoplasm of malignant squamous cells in tumors with histologic evidence of PNI. Immunostaining for NGF (P = .0001) and TrkA (P = .039) was significantly higher in the PNI-positive oral SCC group than in the PNI-negative oral SCC group. CONCLUSION: This study shows that oral SCC with evidence of PNI shows increased expression of NGF and TrkA and suggests that NGF and TrkA are involved with the mechanism leading to PNI. Further investigations are warranted to determine the potential for use of NGF and TrkA as candidate biomarkers to predict progression and outcome

Ongoing and breakthrough pain is a primary concern for the cancer patient. Although the etiology of cancer pain remains unclear, animal models of cancer pain have allowed investigators to unravel some of the cancer-induced neuropathologic processes that occur in the region of tumor growth and in the dorsal horn of the spinal cord. Within the cancer microenvironment, cancer and immune cells produce and secrete mediators that activate and sensitize primary afferent nociceptors. Pursuant to these peripheral changes, nociceptive secondary neurons in spinal cord exhibit increased spontaneous activity and enhanced responsiveness to three modes of noxious stimulation: heat, cold, and mechanical stimuli. As our understanding of the peripheral and central mechanisms that underlie cancer pain improves, targeted analgesics for the cancer patient will likely follow

AIM: The objective of this study was to evaluate the early healing of endosseous implants presenting various healing chamber configurations in a beagle dog mandible model. METHODS: The four premolars of 12 beagle dogs were extracted and allowed to heal for a period of 8 weeks. Implants allowing six different healing chamber configurations were placed in each dog (three per side, six configurations per dog). The animals were sacrificed after 3 and 5 weeks in vivo (n=6 per time in vivo), and the implants were non-decalcified processed to slides of approximately 30 microm thickness. Bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) within the healing chamber were quantified. Statistical analysis was performed by a GLM ANOVA model at 5% significance level. RESULTS: Osseointegration and healing with woven bone filling throughout all healing chambers was observed. Replacement of woven bone by lamellar bone showing primary osteonic structures was observed at 5 weeks. BIC was significantly affected by healing chamber configuration (P<0.001) and was not affected by time in vivo (P>0.42) at 3 and 5 weeks in vivo. BAFO was not affected by healing chamber configuration (P>0.14) however significantly increased over implantation time (P<0.001). CONCLUSION: Regardless of healing chamber design and dimensions considered, healing allowed the devices osseointegration. However, healing chamber configuration significantly affected osseointegration measurable parameters such as BIC.

Even though total absence of elbow flexion in obstetric brachial plexus palsy (OBPP) is rare, weakness is a frequent problem. Numerous procedures for elbow flexion restoration in late obstetric brachial plexus palsy have been described. In this study, children with OBPP who underwent secondary reconstruction for elbow flexion restoration were studied. A retrospective review of 15 patients (16 elbows) who underwent 16 pedicled and eight free-muscle transfers for elbow flexion restoration was conducted. The mean follow-up period was 8.4 +/- 2.9 years (range, 25 months to 12.2 years). The mean age at operation (elbow surgery) was 5.4 +/- 1.9 years. The total arc of elbow motion was the result of the active elbow flexion less the flexion contracture. There was significant improvement in biceps muscle power from an average grading of 2.49 +/- 0.80 preoperatively to 3.64 +/- 0.46 postoperatively (p < 0.001). Thirteen of 16 elbows (81%) achieved good and excellent results (>/=M3+); and three elbows (19%) fair results (M3- or M3). The average arc of motion was significantly improved from 36 degrees +/- 25 degrees preoperatively to 94 degrees +/- 26 degrees postoperatively (p < 0.001). The preoperative and postoperative average elbow flexion contracture was 10.9 degrees +/- 8.9 degrees and 20 degrees +/- 12.2 degrees , respectively. Pedicled and/or free-muscle transfers can significantly improve elbow flexion in late obstetric brachial plexus palsy. Choice of the procedure should be individualized and determined on the basis of the type of paralysis, availability of donor muscles, previous reconstruction, and experience of the surgeon.

Hemangiopericytoma (HPC) is a rare vascular tumor arising from contractile cells around blood vessels, with the potential for malignant degeneration. Up to 10% of HPC occurs in children. Standard therapy for this tumor is surgical excision. We report the case of a 6-month-old infant with giant HPC involving the hand. Chemotherapy resulted in a decrease in tumor size, allowing for salvage of most of the hand and fingers. Preoperative chemotherapy should be considered in the care of HPC tumors involving the upper extremity in children

The indications for free muscle transfer in brachial plexopathies are prolonged denervation time or inadequate upper extremity function after primary nerve reconstruction. The purpose of this study is to analyze the outcomes of free muscle transfer for elbow flexion and extension in brachial plexopathies in relation to the different muscles used and the respective motor donors. Seventy-three muscles were transferred for elbow flexion and ten for elbow extension. Latissimus dorsi (LD) was used in 37 cases, gracilis in 28, rectus femoris (RF) in seven, and vastus lateralis in one. Five LD and five gracilis were transferred for elbow extension. Patients younger than 15 years yielded better results than older patients for elbow flexion. When LD was transferred, the mean muscle grading (MG) was 3.33 +/- 0.25 when the neurotization was from intercostals; these outcomes were statistically significant when compared with outcomes of free gracilis transfer (MG 2.25 +/- 0.6). There was also a statistically significant difference when free LD was neurotized with three intercostals as compared with two intercostals nerves. RF yielded also good results when neurotized from contralateral C7 (cC7; MG 3.67 +/- 0.6). For elbow extension, the better outcomes of LD were not statistically significant. Among all the free muscle transfers for upper extremity reconstruction, elbow reanimation yielded the most rewarding outcomes. The selection of powerful muscle units was more important than the effect of neurotization which was not as strong as it was in muscle transfers for facial or hand reanimation