Mineralized bone loss in partially edentulous trabeculae of ovariectomized rabbit mandibles.

OBJECTIVE: The purpose of this study was to evaluate trabeculae changes in partially edentulous bone in ovariectomized rabbits. BACKGROUND: Numerous clinical studies have suggested that the greater risk for oral bone loss in females may be correlated with osteoporosis after menopause. Knowledge of trabecular changes in partially edentulous bone in animals with loss of ovarian function may be beneficial in the diagnosis and treatment of partially edentulous patients of postmenopausal women. METHODS: Twelve adult female Japanese white rabbits were examined. The mandibular incisors were initially extracted to simulate the partially edentulous bone. Six animals were bilaterally ovariectomized and the other six sham-ovariectomized 12 weeks after tooth extraction. The partially edentulous parts of distal mandibular bodies were processed undecalcified 12 weeks after ovariectomized or sham-ovariectomized surgeries and examined by quantitative trabecular bone histomorphometry. RESULTS: In ovariectomized rabbits, there were significant increases in trabecular separation, osteoid volume, osteoid thickness, osteoid width, eroded surface, and mineral apposition rate, and a significant decrease in trabecular number. CONCLUSION: The results of sparser trabecular structure, more trabecular osteoid, and increased trabecular bone turnover demonstrate mineralized bone loss in partially edentulous trabeculae of ovariectomized rabbit mandibles and suggest that the same loss may occur in postmenopausal women.

Acoustic characteristics of sounds from temporomandibular joints with and without effusion: an MRI study.

Joint effusion has been associated with temporomandibular joint (TMJ) pain but can only be diagnosed by magnetic resonance imaging (MRI). For screening of patients with suspected effusion a simple and less expensive method would be desirable. We recorded joint sounds during jaw opening and closing movement from 34 TMJs with internal derangement (ID). Seventeen joints had joint effusion seen on MRI. Spectrograms of the sounds were displayed as waterfall plots showing profiles of the consecutive Hamming windows. If the profiles were similar, as judged by initial evaluation, the displayed pattern was classified as stable. If some profiles were distinctly deviating in their pattern, this was classified as unstable. Joints with effusion showed unstable sound pattern more often than joints without effusion (P < 0.001). It was concluded that TMJ sound analyses have a potential to identify joints with effusion based on their unstable sound pattern.

Bone mineral density in mandibles of ovariectomized rabbits.

The purpose of this study was to evaluate the association between loss of ovarian function and bone mineral density changes in the mandibles of ovariectomized rabbits using peripheral quantitative computed tomography. Twenty-four adult female Japanese white rabbits were used in this experiment. The mandibular incisors were initially extracted to create implant bone. Twelve animals were bilaterally ovariectomized and the other twelve sham-ovariectomized 12 weeks after tooth extraction. All rabbits were sacrificed at 4 and 12 weeks after ovariectomy and sham-ovariectomy, with 6 rabbits in each of the four resultant groups. The edentulous parts of distal mandibular bodies were measured by peripheral quantitative computed tomography. There were significant decreases in total bone mineral density and trabecular bone mineral density in the mandibles of rabbits at 12 weeks post-ovariectomy. The results demonstrate the mineralized bone loss in the mandibles of ovariectomized rabbits.

Perception of lateral misarticulation and its physical correlates.

In order to clarify the relationship between perceptual diagnosis of lateral misarticulation (LM) by sophisticated listeners and the physical correlates of LM, three experiments using sustained speech /integral/ were conducted. Experiment 1 was designed to compare the spectral envelopes of normal speech (NS) /integral/ with those of LM /integral/. Experiment 2 was designed to collect the auditory impressions of sophisticated listeners listening to LM and NS /integral/ with specific spectral envelope bands replaced by LM. These two experiments showed that: (1) the spectral envelopes of LM are flat or decrease along the frequency axis in the frequency band above approximately 4 kHz, and there is a substantial peak at around 3.2 kHz in LM, which varies peculiarly with time; (2) the replacement of the spectral envelope between 2.5 and 4.5 kHz of NS with that of LM resulted in a remarkable increase in auditory impressions of LM. The facts suggest that the spectral envelope characteristic of LM has a peculiar variation at around 3.2 kHz. Additionally, experiment 3 estimated the spectrum of sustained speech /integral/ using vocal tract area functions. The results suggest that typical peaks of LM are related to the length and position of the vocal tract constriction region.

The effects of transplantation of osteoblastic cells with bone morphogenetic protein (BMP)/carrier complex on bone repair.

We investigated the effects of transplantation of osteoblastic cells with a bone morphogenetic protein (BMP)/carrier complex on bone repair by in vitro and in vivo experiments. Poly-D,L-lactic-co-glycolic acid/gelatin sponge (PGS) was used as a carrier for cell transplantation. In the in vitro experiments, three cell types, C3H10T1/2 cells, MC3T3-E1 cells, and primary osteoblastic cells, isolated from newborn rat calvariae (ROB cells), were cultured for 2 weeks on PGS alone or PGS containing BMP-2 (PGS/BMP). C3H10T1/2 cells cultured on PGS/BMP expressed several markers related to differentiation of both osteoblasts and chondrocytes, such as alkaline phosphatase (ALP) activity and mRNAs for osteocalcin and aggrecan, whereas the cells cultured on PGS alone expressed no such markers. MC3T3-E1 cells cultured on PGS/BMP exhibited a more ALP-positive cells than those cultured on PGS alone. PGS/BMP promoted ROB cell differentiation into both osteoblasts and chondrocytes. In the in vivo experiments, we transplanted ROB cells, which had been cultured on PGS alone or PGS/BMP in vitro for 2 weeks, into bone defects created in rat calvariae. Transplantation of ROB cells cultured on PGS alone generated little new bone. Transplantation of ROB cells cultured on PGS, which absorbed a low dose (10 ng) of rhBMP-2,; induced significantly higher bone mineral content than PGS/BMP alone, although application of a high dose (1 microg) of rhBMP-2 induced no difference in bone mineral content between transplantation of PGS/BMP with or without ROB cells. These results show that transplantation of osteoblastic cells after induction of osteoblast maturation in vitro by cultivation on PGS/BMP is a potent technique for cell therapy of bone repair.

Analysis of the articulation after glossectomy.

Rehabilitation of the oral cancer patient should aim to achieve not only morphological restoration but also post-operative functions. However, there are few reports describing quantitative evaluation of the latter. The authors have attempted quantitative evaluation of post-operative articulatory function after glossectomy, and report the evaluation of it by speech intelligibility, electropalatography (EPG), and acoustical analysis. Subjects were five directly sutured patients and five patients reconstructed with forearm flap, all after glossectomy. The target syllable was /ta/ from among speech intelligibility test samples. The speech intelligibility and acoustical analysis were investigated pre-operation, and 1,6 and 12 months post-operation. EPG data were collected by DP-01(RION) at 6 months post-operation. Acoustical analyses were carried out by consonant frequency characteristics and formant variance from consonant to vowel transitions. As a result, subjects reconstructed with a forearm flap showed higher restorative tendency than directly sutured subjects. Articulatory characteristics expected from acoustical analysis were more in agreement with the results of EPG than with the results of the speech intelligibility test. From the results, it was suggested that the acoustical analysis used for this research could reveal changes in articulatory movement and will be useful for quantitatively evaluating post-operative articulatory functions.

Experimental reconstruction of mandibular defects with vascularized iliac bone grafts.

PURPOSE: The study evaluated the processes of incorporation and bone remodeling after microsurgical transplantation of iliac crest grafts for mandibular defect reconstruction. MATERIALS AND METHODS: A defect in the mandibular angle measuring 2 x 4 x 1 cm was reconstructed in six Göttingen minipigs with a microvascularized iliac bone graft based on the circumflex artery. The animals were killed at 14, 28, and 56 days after transplantation and the healing process was histologically examined. RESULTS: Although a constant vascular supply to the graft was restored by the microvascular reanastomosis, necrosis occurred in the major part of the bone marrow. New bone formation from the graft was markedly delayed compared with that from the mandible. Some osteocytes and marrow survived after grafting, but the volume of iliac bone tended to decrease gradually over time. In the 56-day specimens, the border between the graft and the mandible was not clear. CONCLUSION: These findings indicate that survival of the vascularized iliac bone graft in the minipig is not complete.