Contribution to Bone Formation of the Schneiderian Membrane after Sinus Augmentation: A Histological Study in Rabbits.

AIM: to evaluate bone formation in close contact with the sinus mucosa after different periods from sinus augmentation and the influence on healing of the presence of an inward dis-placed bone window. MATERIAL AND METHODS: Eighteen rabbits were included in the experiment. A trap-door technique was applied at the test sites, and the bony window was elevated inward (inward window; IW) together with the sinus mucosa. At the control sites, the bony window was removed before the elevation of the sinus mucosa. The elevated space was filled with deproteinized bovine bone mineral (DBBM) and both access windows were covered with a collagen membrane. Histometric measurements were performed subjacent the sinus mucosa after 2, 4, and 8 weeks of healing. RESULTS: Very few sinuses presented small percentages of new bone in close contact with the sinus mucosa in the various period examined. The presence of bone in the neighbor areas might have influenced bone formation close to the sinus mucosa. The inward displaced bone window supported bone formation close to the sinus mucosa only in the earliest period of healing, while the bone walls increased their influence over time. The lack of increased new bone percentage over time in the most central regions of the elevated sinus mucosa do not support the hypothesis that the sinus mucosa may express its potential in bone formation. It can be speculated that the new bone found in the intermediate and middle regions of the control sites in the earliest period of healing might be due to residual of bone from the osteotomy. CONCLUSIONS: Very small amounts of new bone were found subjacent to the sinus mucosa, mostly formed from the bone walls, the inward displaced bone window or from possible bone residues from the osteotomy procedures. The lack of increased new bone percentage over time in the most central regions of the elevated sinus mucosa indicates that the contribution to bone formation provided by the sinus mucosa is limited.

Metal artifacts in MRI from non-magnetic dental alloy and its FEM analysis.

Artifacts in MR(Magnetic Resonance) images of oral cavity produced from non-magnetic metal restorations was verified by measuring the image of index finger and a cylinder of fat test piece with a type 4 gold alloy ring using a compact MRI equipment. In the images of finger, portion around the ring disappeared. However, it was nearly restored with a cut ring. In the cylinder of fat test piece, obvious artifacts appeared when circumferential surface of the ring was placed perpendicular to RF(Radio Frequency) field of MRI equipment's excitation/detection coil. However, in other directions or with a cut ring, artifact disappeared. The cause was simulated with FEM(Finite Element Method) electromagnetic field analysis, and alternating magnetic field was shown to induce surface current on the continuous gold ring. Magnetic field produced by that current interfered with the field from excitation coil. This demonstrated the characteristics and cause of artifacts by non-magnetic dental metals.

Craniofacial morphology in a patient with Simpson-Golabi-Behmel syndrome.

OBJECTIVE: We present the case of a 6-year-old boy with a coarse face, cleft palate, and malocclusion with anterior open bite who had been diagnosed with Simpson-Golabi-Behmel syndrome. Morphology of the craniofacial structures was examined on the basis of conventional radiographs, three-dimensional (3D) computed tomography (CT) and magnetic resonance (MR) scanning. PATIENT: This patient had 13 ribs on the right side, slight scoliosis, supernumerary nipples, a coarse face, hypertelorism, a short broad upturned nose, a wide mouth, a straight facial profile with incompetence of the lips, midline groove of tongue, and cleft palate. The patient also had severe anterior open bite, a distal step-type molar relationship, five congenitally missing teeth, and a supernumerary tooth. Lateral cephalometric analysis revealed a large anterior cranial base, a large maxilla and mandible, a large inferior face height, and skeletal Class I jaw relationship with a high mandibular plane angle and large gonial angle. The 3D CT image showed a large cranium, a long face height, and prominent skull sutures. The MR image showed a large tongue, midline groove of the tongue, and a small space between tongue and palate.