Faculty Bibliography

BACKGROUND: Novel implant surface treatments with a nanothickness bioactive ceramic deposition onto rough surfaces have been recently introduced. This study aims to evaluate histologically and histomorphometrically (bone-to-implant contact [BIC] and bone area fraction occupancy [BAFO]) the early bone response to plasma-sprayed calcium-phosphate (PSCaP)-coated versus a 300- to 500-nm thickness bioactive ceramic nano-coated plateau root form implants in a rabbit femur model. METHODS: A total of 48 plateau root form implants were bilaterally placed in the distal aspect of the femur of 12 white New Zealand rabbits, remaining for 20, 30, and 60 days in vivo (n = 4 animals per time in vivo, n = 2 implants per surface per animal). After sacrifice, the implants in bone were non-decalcified processed to slides of approximately 30 mum thickness, and were morphologically and morphometrically (BIC and BAFO) evaluated. RESULTS: Higher degrees of bone structural organization were temporally observed for the PSCaP surface compared to the nano surface over time. BIC and BAFO was significantly higher (P <0.05) for PSCaP at all implantation times evaluated. CONCLUSIONS: Within the limits of this study it is possible to state that bioactive ceramic coatings of both thicknesses were biocompatible and osteoconductive. However, the early bone response was favored by the presence of the thicker PSCaP coating.

Optimized experimental conditions for extracting accurate information at subpixel length scales from analyzer-based X-ray imaging were obtained and applied to investigate bone regeneration by means of synthetic beta-TCP grafting materials in a rat calvaria model. The results showed a 30% growth in the particulate size due to bone ongrowth/ingrowth within the critical size defect over a 1-month healing period.

Calcium phosphate-based bioactive ceramics in various physical and chemical formulations have been extensively utilized as biomaterials for bone regeneration/conduction. However, the determination of their in vivo temporal behavior from the short to long term in humans has been a challenge due to the lack of physical reference for morphologic and morphometric evaluation. The present study evaluated bone morphology and morphometry (bone-to-implant contact [BIC]) around plasma-sprayed hydroxyapatite (PSHA)-coated endosseous implants that were retrieved due to prosthetic reasons while successfully in function at the posterior region of the jaws from as early as 2 months to approximately 13 years after a 6-month healing period after placement. Bone morphology was evaluated by light microscopy, and BIC was determined using computer software. Irrespective of the time in vivo, lamellar bone was observed in close contact with the implant PSHA-coated surface and between plateaus. BIC ranged from approximately 35-95%, was highly directional, and Haversian-like osteonic morphology between plateaus was observed for most implants. The PSHA coating was present with little variation in thickness between the samples retrieved regardless of time in vivo.

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.

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.

Microvascular free tissue transfer is a ubiquitous and routine method of restoring anatomic defects. There is a paucity of data regarding the role of perioperative antibiotics in free tissue transfer. We designed a survey to explore usage patterns among microvascular surgeons and thereby define a standard of care. A 24-question survey regarding the perioperative antibiotic use in microvascular head and neck, breast, and lower extremity reconstruction was sent to all those members of the American Society for Reconstructive Microsurgery who had registered e-mail addresses ( N = 450). Ninety-nine members responded. A first-generation cephalosporin is the most frequent choice of perioperative antibiotics across most categories: 93.5% for breast, 59.2% for head and neck, 91.1% for nontraumatic lower extremity, and 84.9% for traumatic noninfected lower extremity reconstruction. In penicillin-allergic patients, clindamycin is the most common choice. For traumatic lower extremity reconstruction in the presence of soft tissue infection or osteomyelitis, culture and sensitivity results determine the selection of perioperative antibiotics in 74%. A first-generation cephalosporin is the standard of care for perioperative antibiotic use in microvascular breast, head and neck, nontraumatic lower extremity, and traumatic noninfected lower extremity reconstruction. No consensus exists regarding the appropriate duration of coverage. These data may serve as a guide until a large controlled prospective trial is performed and a standard of care is established.

Although radiation therapy is a major risk factor for the development of lymphedema following lymphadenectomy, the mechanisms responsible for this effect remain unknown. The purpose of this study was therefore to determine the effects of radiation on lymphatic endothelial cells (LECs) and lymphatic function. The tails of wild-type or acid sphingomyelinase (ASM)-deficient mice were treated with 0, 15, or 30 Gy of radiation and then analyzed for LEC apoptosis and lymphatic function at various time points. To analyze the effects of radiation fibrosis on lymphatic function, we determined the effects of transforming growth factor (TGF)-beta1 blockade after radiation in vivo. Finally, we determined the effects of radiation and exogenous TGF-beta1 on LECs in vitro. Radiation caused mild edema that resolved after 12-24 wk. Interestingly, despite resolution of tail edema, irradiated animals displayed persistent lymphatic dysfunction. Radiation caused loss of capillary lymphatics and was associated with a dose-dependent increase in LEC apoptosis. ASM-/- mice had significantly less LEC apoptosis; however, this finding did not translate to improved lymphatic function at later time points. Short-term blockade of TGF-beta1 function after radiation markedly decreased tissue fibrosis and significantly improved lymphatic function but did not alter LEC apoptosis. Radiation therapy decreases lymphatic reserve by causing depletion of lymphatic vessels and LECs as well as promoting soft tissue fibrosis. Short-term inhibition of TGF-beta1 activity following radiation improves lymphatic function and is associated with decreased soft tissue fibrosis. ASM deficiency confers LEC protection from radiation-induced apoptosis but does not prevent lymphatic dysfunction.

BACKGROUND AND OBJECTIVE: The most common risk factor for bisphosphonate-related osteonecrosis of the jaws (BRONJ) is dentoalveolar surgery. It has been suggested that reduced serum C-terminal telopeptide (CTX) can determine the degree of osteoclast suppression and may predict the development of BRONJ after dentoalveolar surgery. Although there are many radiographic appearances associated with BRONJ, there are little data that describes changes preceding dentoalveolar surgery. The objective of this retrospective study was: 1) to investigate if reduced serum CTX values (i.e., <150 pg/mL) were associated with BRONJ after dentoalveolar surgery; and 2) to determine if specific radiographic changes are associated with teeth that develop BRONJ after extraction. STUDY DESIGN: A retrospective review of radiographic and/or serum CTX data was performed for 68 patients with a history of bisphosphonate therapy who either underwent dental extraction or were diagnosed with BRONJ in the Department of Oral and Maxillofacial Surgery during the period 2007-2009. Postoperative healing was assessed for 26 patients with reduced serum CTX levels (<150 pg/mL) who either underwent dental extraction or treatment for BRONJ. Preoperative radiographs were evaluated for 55 patients who either healed normally or developed BRONJ after dental extraction. RESULTS: All 26 patients (100%) who had serum CTX levels <150 pg/mL healed successfully after dentoalveolar surgery (20 patients) or after treatment for BRONJ (6 patients). Among the 55 patients who underwent radiographic evaluation, 24 patients (83%) with BRONJ exhibited periodontal ligament (PDL) widening associated with extracted teeth, whereas only 3 patients (11%) who healed normally demonstrated PDL widening. CONCLUSION: These data suggest that radiographic PDL widening may be a more sensitive indicator than CTX testing in predicting risk of BRONJ. Current guidelines that recommend minimal surgical intervention may need to be revised to include alternative strategies for the elimination or management of this pathology.

Head and neck reconstruction is a multidisciplinary field, requiring communication among various surgical and dental specialists. The free fibular flap is the standard method for reconstructing large mandibular defects after benign or malignant tumor ablation. The graft has to be precisely contoured to fit the three-dimensional defect to meet the functional and aesthetic goals.Virtual surgical planning using computed tomographic imaging and computer-aided design and manufacturing technology allows the surgeons to perform virtual surgery and generates templates and cutting guides that allow for the precise and expedient recreation of the plan in the operating room. The authors describe 2 cases where virtual planning was used for the extirpative and reconstruction phases to achieve precise reconstruction and decreased time under anesthesia.