Reconstruction of a cranial bone defect with hydroxyapatite and free flap transfer.

The authors report a successful reconstruction of an extensive frontotemporal bone defect after craniotomy, which was complicated with infection and necessitated removal of frontal and temporal bones. The large frontotemporal bone defect was reconstructed using prefabricated hydroxyapatite blocks in combination with the free vastus lateralis muscle flap. The patient's functional and cosmetic restoration has been maintained for 10 months' follow-up.     

A scanning electron microscopic study of the contraction of vascular wall cells in dog dental pulp

Ultrastructural changes in vascular wall cells in dog dental pulp after removal of connective tissue components were studied by scanning electron microscopy following administration of norepinephrine (0.2 mg/kg). Contracted smooth-muscle cells were frequently seen in arterioles of all sizes. The surfaces of these cells were highly irregular with numerous evaginations and invaginations, varying considerably in configuration and size. Many evaginations ran longitudinally or obliquely to the long axis of the vessel. Some meandering evaginations were also observed as, rarely, were small spherical or bulbous projections. Spidery smooth-muscle cells frequently seen in the tunica media of terminal arterioles and thought to be primitive smooth-muscle cells exhibited fewer irregularities than the typical spindle-shaped smooth-muscle cells beneath them. Pericytes in the larger post-capillary venules (20 microns or larger in diameter) often showed evaginations and invaginations, mainly running parallel to the vessel axis. On the other hand, no surface irregularities could be seen in pericytes of either the smaller post-capillary venules (less than 20 microns in diameter) or the capillaries, although occasional evaginations running parallel to the vessel axis were noted on the outer surface of the endothelium.     

Strength and elastic modulus of fiber-reinforced composites used for fabricating FPDs

PURPOSE: The purpose of this study was to examine the flexural strength and elastic modulus of a new fiber-reinforced composite used for the fabrication of inlay-retained fixed partial dentures (FPD). MATERIALS AND METHODS: A total of six materials were used: Vectris, FibreKor, and an experimental material, BR-100, were the types of glass fiber preimpregnated with resin used for making the frameworks; Targis, Sculpture, and Estenia were used as the veneering composites. Five specimens of each material were prepared. Flexural strength and elastic modulus were determined using the three-point bending test. In addition, laminate specimens were fabricated by combination of the veneering composite and framework materials (Targis/Vectris, Sculpture/FibreKor, and Estenia/BR-100), and fracture loads of these specimens were determined. Laminate specimens were fabricated with three different framework thicknesses for Estenia/BR-100. RESULTS: Estenia had the greatest strength and highest modulus of elasticity of the veneering composites. All three framework materials had flexural strength values (567 to 686 MPa) more than three times as great as those of the veneering composites (132 to 193 MPa). Of the laminate specimens, the Estenia/BR-100 with a framework thickness of 1.0 mm had a fracture load more than 50% greater than Targis/Vectris and Sculpture/FibreKor. CONCLUSION: The combination of the experimental framework material BR-100 and the composite Estenia showed higher fracture loads than the other combinations tested.     

Immunohistochemical co-localization of lymphatics and blood vessels in oral squamous cell carcinomas

BACKGROUND: Differentiating lymphatic vessels from blood vessels is difficult, partly due to the lack of a specific method for identifying lymphatics. A new lymphatic vessel-reactive antibody, D2-40 has recently become commercially available. We examined the selectivity of D2-40 for lymphatics in oral neoplastic lesions for discrimination from blood vessels. METHODS: Formalin-fixed, paraffin-embedded sections of oral lymphangiomas (n = 3), oral hemangiomas (n = 7), and oral squamous cell carcinomas (OSCC, n = 46) were double immunostained with D2-40 and anti-CD34 monoclonal antibodies (MoAb) using ENVISION-polymer technique with 5-bromo-4-chloro-3-indoxyl-phosphate (BCIP)/nitroblue tetrazolium chloride (NBT) and 3,3'-diaminobenzidine (DAB) as color reagents, respectively. Results: In the oral lymphangiomas and hemangiomas D2-40 was detected in all lymphatics, while all blood vessels were positive for CD34. In OSCC, number of vessels for lymphatics (P < 0.01) and for blood vessels in the perineoplastic areas were significantly greater than those in intratumoral areas. CONCLUSIONS: These results indicate that lymphatic proliferation might be much more extensive in the peritumoral area than intratumoral.     

Effect of water temperature on the fit of provisional crown margins during polymerization

STATEMENT OF PROBLEM: When fabricating a provisional crown with the direct technique, dentists are concerned with margin discrepancies that result from polymerization shrinkage. PURPOSE: This in vitro study examined the effect of water temperature on the fit of provisional crown margins during resin polymerization. MATERIAL AND METHODS: The experiment was designed to simulate a direct technique to fabricate provisional crowns. After mixing autopolymerizing methyl methacrylate resin, the material was placed in a preformed polycarbonate crown. The crown was seated on a prepared premolar-shaped die with a shoulder margin. After 1 minute and 50 seconds, the crown was removed and polymerization was continued under the following conditions: 20 degrees C air, and water at 0 degrees C, 10 degrees C, 20 degrees C, 30 degrees C, 40 degrees C, 60 degrees C, and 80 degrees C. Six minutes after polymerization, the crown was trimmed and reseated on the die. Discrepancy of crown margin was measured with a 3-dimensional digitizer. RESULTS: Margin discrepancy varied with the condition during resin-polymerization (ANOVA, P <.001). The crowns polymerized in 20 degrees C and 30 degrees C water revealed the best margin fit, showing 3 times more accurate margin fit than those polymerized in 20 degrees C air (Bonferroni/Dunn procedure, P <.01). CONCLUSION: Conditions during resin polymerization were significant factors that affected margin fit of provisional crowns using the direct technique. Water temperatures of 20 degrees C and 30 degrees C produced the best fit at the margin of the provisional crown.     

Radiographic examination of the mandibular (glenoid) fossa in ancient and modern man

OBJECTIVE: To compare the morphology of the mandibular (glenoid) fossa between ancient and modern Japanese. METHODS: There were 221 specimens from the ancient period and 206 specimens from the modern period. Radiographs of the mandibular fossa were obtained using a modified Schuller technique and were studied. The length, depth, and area of the mandibular fossa and angulation of the frontal slope of the mandibular fossa on the radiographs were automatically computed. In addition, morphological changes of the mandibular fossa in the ancient or modern periods on radiographs were evaluated in order to assess tendency of temporomandibular joint disorder (TMD). RESULT: The ratio of mandibular fossa having morphological alternation in the modern period was greater than that in the Yayoi. Differences in the length and area between the right and left sides became progressively larger from the Yayoi to modern periods. The angulation of the anterior slope of the mandibular fossa in the modern period was smaller than that in other periods. CONCLUSION: The morphology of the mandibular fossa was shown to have changed and asymmetry has increased from the Yayoi to modern periods. It can be speculated that this change in morphology of the mandibular fossa in the modern period is the result of an increase of TMD.     

The elastic modulus of the temporomandibular joint disc from adult dogs.

The present study was designed to measure the elastic properties of temporomandibular joint (TMJ) discs from six adult dogs. Each disc was divided mediolaterally into medial, middle, and lateral parts. Under tension, the articular disc exhibited a non-linear stress-strain relationship, which could be represented as two lines (two moduli of elasticity) connected at a point of stress around 1.5 MPa. These two elastic moduli of the disc were approximately 44 MPa and 92 MPa in the lower- and higher-stress regions, respectively. Elastic moduli of the articular disc in the middle area were significantly different from that in the lateral area of the disc. The reaction to external force appeared to be different in the medial, middle, and lateral regions of the disc.     

Adhesive bonding of titanium with a titanate coupler and 4-META/MMA-TBB opaque resin

Adhesive bonding of titanium was evaluated with a titanate primer and adhesive opaque resin. The primer consisted of 2% isopropyl dimethacryloyl isostearoyl titanate in methyl methacrylate. The adhesive was 4-META/MMA-TBB opaque resin that contained 4-methacryloyloxyethyl trimellitate anhydride and was initiated by tri-n-butylborane derivative. Titanium discs were machined and blasted with aluminum oxide. They were primed and bonded together with the opaque resin. A shear test was performed after repeated thermocycles for investigation of the durability of the bond. The shear strength of the primed and 4-META resin-bonded specimens was 37.2 MPa after 50,000 thermocycles, with only a small decrease in bond strength. This was significantly higher than the control values. Thus, titanate primer and 4-META/MMA-TBB opaque resin may be used for the bonding of titanium in prosthodontic practice.