Combined Testing of p16 Tumour-suppressor Protein and Human Papillomavirus in Patients With Oral Leukoplakia and Oral Squamous Cell Carcinoma.

BACKGROUND: Oral leukoplakia (OL) is a potentially malignant oral mucosal disorder. A casual association between OL, oral squamous cell carcinoma (OSCC) and human papillomavirus (HPV) infection has been suggested, but no conclusive evidence has been presented. p16, a tumour-suppressor protein, is used as a surrogate marker for HPV infection. The aim of this study was to investigate how overexpression of p16 correlates with HPV infection in OL and in OSCC. PATIENTS AND METHODS: Seventy-four patients with OL and 13 with OSCC with p16 overexpressed, were analyzed by immunohistochemistry visualizing p16 and a real-time polymerase chain reaction (PCR) assay targeting HPV types 6, 11, 16, 18, 31, 33, 35, 39, 45, 52, 56, 58 and 59. RESULTS: Overexpression of p16 was observed in 18% of patients with OL. None of the HPV subtypes were detected by PCR analysis in patients with OL. In the p16-positive OSCC specimens, 38% were also HPV16-positive. CONCLUSION: Overexpression of p16 was not found to be a reliable biomarker for HPV infection in patients with OL and OSCC.

Histology of retrieved immediately and early loaded oxidized implants: light microscopic observations after 5 to 9 months of loading in the posterior mandible.

BACKGROUND: An increased number of publications report that one-stage surgery and immediate/early loading of dental implants may be a feasible approach for prosthetic reconstruction of the edentate patient. However, little is known about the histologic response to implants subjected to immediate/early loading in patients. PURPOSE: The aim of the present study was to histologically evaluate oxidized titanium implants subjected to loading immediately following surgery or after 2 months of healing and removed after 5 to 9 months loading. MATERIALS AND METHODS: Five patients participated in the study; each had consulted for implant treatment in the posterior mandible and subsequently volunteered to have extra implants inserted for the purpose of histologic research. Nine oxidized titanium implants (Brånemark System TiUnite , Nobel Biocare AB, Gothenburg, Sweden) were retrieved after 5 to 9 months in function. Two implants had been loaded the same day, whereas seven implants were loaded after 2 months of healing. Resonance frequency analysis was performed at retrieval on seven implants. Ground sections were prepared for histology and analyzed using light microscopic morphometry. RESULTS: Seven and 8.5 mm implants were placed, predominantly in quality 3 and 4 bone. Four implants were straight (Mk III), and five were tapered (Mk IV). All implants were clinically stable at retrieval and showed ISQ values of 65 to 79 with a mean of 71.4 +/- 4.4. Eight of the implants were able to be used for histology. A gross histologic examination showed an undisturbed healing of soft and bone tissues with no apparent differences between response to immediately and early loaded implants. Lamellar bone surrounded the implants, and remodeling was evident and more marked near the implant surface. A condensation of bone toward the implant surface was seen; this resulted in a lamina dura-like structure in trabecular bone. Thin rims of newly formed bone were often seen following the contour of the implant surface. The morphometric measurements showed a mean bone-to-implant contact value of 84.2 +/- 10.5% and a mean bone area value of 79.1 +/- 6.8%. The two immediately loaded implants showed bone-to-implant contact and bone area values of 92.9 +/- 0.1% and 84.9 +/- 0.9%, respectively. The corresponding values for the six early loaded implants were 81.4 +/- 10.6% and 77.1 +/- 6.8%, respectively. CONCLUSIONS: The present study demonstrated that oxidized implants subjected to immediate or early loading do integrate with soft and bone tissues in the posterior mandible.

Placement of autogeneic bone chips or bovine bone mineral in guided bone augmentation: a rabbit skull study.

PURPOSE: Our primary aim was to use a rabbit guided bone augmentation model to evaluate whether use of autogeneic bone grafts or bovine bone mineral (BBM) combined with a space-making barrier enhances bone augmentation compared with a barrier alone. MATERIALS AND METHODS: Sixteen rabbits were studied. In each rabbit, 2 titanium cylinders, each with 1 titanium lid, were placed subcutaneously in perforated slits made in the cortical bones, with their open ends facing the parietal bones. One cylinder was left empty and the other was filled with either autogeneic skull bone chips or BBM. Bone labels were injected after 4 and 11 weeks. After 12 weeks, the animals were sacrificed to obtain ground sections for histology and histomorphometry. RESULTS: Significantly more tissue was augmented in the 2 test groups than in the control group. Most of the autografts were resorbed, leaving only minute amounts in the upper third of the cylinders. Slender new bone trabeculae were distributed mainly from the contiguous bone plate that had no contact with the remaining graft material. In the BBM group, most of the BBM remained evenly distributed in the cylinder. In the upper third of the cylinder, the BBM was surrounded by soft connective tissue, while in the lower two thirds, mainly mineralized bone enclosed the BBM. Equal amounts of mineralized bone were found in both test groups. Comparisons of contact between bone and BBM on one hand and bone and bone cylinder wall on the other revealed that the greatest bone contact was with the BBM in the lower third of the cylinder. In the middle and upper third of the cylinder, bone-BBM contact and bone-cylinder wall contact were similar. Fluorescent label intensity was higher in the autograft group than in the BBM group. In all 3 groups the intensity of the early label was similar to that of the late label, indicating that the graft materials do not seem to retard mineralization. DISCUSSION: BBM was found to promote as much new bone as did autogeneic bone. In addition, BBM appears to have at least the same osteoconductive properties as titanium, provided BBM is contained in a stable environment. CONCLUSIONS: Placement of autogeneic bone or BBM in conjunction with a stiff space-making barrier generated more tissue than a barrier only. In this model, autogeneic bone chips and BBM augmented similar amounts of new mineralized bone.

Early bone tissue responses to turned and oxidized implants in the rabbit tibia.

BACKGROUND: Previous studies have shown the formation of more bone contacts with a moderately rough and porous titanium surface, created by anodic oxidation, as compared with nonmodified turned titanium control surfaces. The mechanisms leading to a stronger bone response to oxidized titanium are not well understood. PURPOSE: The aim of the study was to describe the early events of bone integration of titanium implants with oxidized and turned surfaces. MATERIALS AND METHODS: Nine adult New Zealand White rabbits and 18 implants were used in the study. One oxidized and one turned threaded titanium implants, which had been placed in the right tibial metaphysis, were analyzed in the present study. The implants were retrieved after 7, 14, and 28 days for light microscopic examination and histomorphometric measurements in ground sections. RESULTS: Integration of oxidized implants was seen to occur as direct bone formation on the surface, while the integration of turned implants was a result of bone ingrowth from preexisting bone and bone marrow. For oxidized implants, an almost acellular, darkly stained layer was seen after 7 to 14 days, which later became populated with osteoblasts. The presence of osteoid seams indicated appositional bone growth from the substrate toward the surrounding tissues. The bone contact values were higher for oxidized implants, and the bone area values were higher for turned implants. CONCLUSIONS: The present study confirms the idea that implant surface modification alters the bone tissue response to titanium. The early bone formation following surgery occurs directly on the moderately rough oxidized surface, while turned titanium surfaces are integrated by the ingrowth of bone from the adjacent bone marrow and preexisting bone tissues.