Ken-ichi Michi

Methodology for detecting swallowing sounds

The use of cervical auscultation in the evaluation of the pharyngeal swallow may become a part of the clinical evaluation of dysphagic patients. Though its use is based on subjective evaluation, an acoustic analysis of swallowing sounds might establish more objective criteria in the detection of swallowing disorders. The present study sought to investigate three aspects of the methodology for detecting swallowing sounds: (1) the type of acoustic detector unit suited to an acoustic analysis of the pharyngeal swallow, (2) the type of adhesive suited for the attachement of the detector, and (3) the optimal site for sound detection of the pharyngeal swallow. An accelerometer with double-sided paper tape was selected as the appropriate detector unit because of its wide range of frequency response and small attenuation level. Using this detector unit, swallowing sounds and noise associated with simulated laryngeal elevation and the carotid pulse were acquired at 24 sites on the neck in 14 normal subjects; these signals were acoustically analyzed. The determination of the optimal site for detecting swallowing sounds was based on the signal-to-noise ratio. The site over the lateral border of the trachea immediately inferior to the cricoid cartilage is the optimal site for detection of swallowing sounds because this site showed the greatest signal-to-noise ratio with the smallest variance. The site over the center of the cricoid cartilage and the midpoint between the site over the center of the cricoid cartilage and the site immediately superior to the jugular notch were also considered to be the most appropriate sites.

Bone reactions to titanium screw implants in ovariectomized animals

OBJECTIVE The purpose of this study was to investigate the reactions of bone tissue after the placement of implants into the tibiae of osteopenic model rats. STUDY DESIGN Commercially pure titanium screw implants were placed in the bilateral proximal tibial metaphyses 168 days after ovariectomy had been performed on 12-week-old female Wistar rats. For control purposes, implants were similarly placed in sham-ovariectomy rats. The healing process was examined histologically by means of undecalcified sections at various intervals from 7 to 168 days after implantation. Through use of an automated imaging analytic system, changes in relative bone mass and implant-bone contact were histomorphometrically evaluated. RESULTS In the cortical bone area, only a slight difference in bone contact was noted with the implant until 28 days after implantation. However, ovariectomy significantly affected bone contact at 56 days after implantation. The rate of bone contact in the cancellous bone area and the relative bone mass around the implant were significantly lower in the test group than in the control group. CONCLUSIONS It is considered that a decrease in bone mass causes a reduction in the contact area between implant and bone and may also cause a reduction in the supporting ability of the implant because of thinning of the surrounding bone tissue.

Bone reactions around hydroxyapatite-coated implants in ovariectomized rats☆☆☆

OBJECTIVE The purpose of this study was to investigate bone reaction after implantation in an estrogen-deficient state by examining the changes in bone reactions within tissue surrounding implants in ovariectomized rats. STUDY DESIGN Ninety-six 12-week-old female Wistar rats were used in the study; they were divided into 2 groups, an ovariectomized group and a sham-operated group. Hydroxyapatite-coated implants were placed in the proximal metaphyses of the tibiae 21 days after surgery. The tibiae were examined histologically by undecalcified sections at various intervals from 7 to 168 days after surgery. RESULTS In the cortical bone area of the ovariectomized rats, the procedure did not induce any apparent changes in bone volume around the implant or in bone contact with the implant in comparison with the sham-operated rats. In contrast, both bone volume around the implant and contact of the implant with new bone were significantly decreased in the cancellous bone area in the ovariectomized rats in comparison with the sham-operated rats. CONCLUSIONS Ovariectomy did not seriously affect bone healing after the placement of implants in cortical bone areas, but it reduced the bone contact ratio and the bone in the cancellous bone area.

A comparison of surgical and prosthetic treatment for speech disorders attributable to surgically acquired soft palate defects

Surgical and prosthetic treatments for speech disorders attributable to surgically acquired soft palate defects were investigated. Ten patients who had undergone soft palate resection for extensive cancer served as the subjects. In four patients, the resected portion of the soft palate was confined to the anterior or middle segments, with an intact posterior band, whereas in the remaining six patients the resected portion extended into the posterior edge. An obturator with or without a speech appliance was adapted to all patients in the former group and to one patient in the latter group. The remaining five patients in the latter group underwent surgical reconstruction using a free radial forearm flap immediately after resection of the soft palate. The speech of each patient was evaluated either before and after surgery in those treated only surgically or with and without the obturator in the other patients using a standard intelligibility test of 100 Japanese syllables. These tests showed that two of the four patients with a posterior band of soft palate remaining postsurgically achieved excellent restoration of speech and improvement of velopharyngeal function following placement of a special prosthesis. The patients who had resection extending into the posterior edge of the soft palate obtained better restoration of speech and function from surgical reconstruction rather than prosthetic management. All three patients who had surgical reconstruction, in whom the special obturator was applied achieved a slight increase in speech intelligibility scores resulting from the improvement of velopharyngeal function. These results suggest that surgical reconstruction and prosthetic management may best be applied selectively based on the extent of resection of the soft palate.

Ultrasonographic evaluation during reduction of zygomatic arch fractures

Ultrasonography was utilized in three cases of zygomatic arch fracture to confirm the position of the fragments during surgery. Ultrasonography revealed the nature of the fracture clearly and real-time imaging aided its reduction. Accordingly, ultrasonography is considered to be useful to confirm the position of fragments of the zygomatic arch during reduction.

Symmetry and reproducibility of swallowing sounds

Cervical auscultation is being used more frequently in the clinical assessment of dysphagic patients. The present study was designed to assess symmetry and the reproducibility of swallowing sounds detected simultaneously from bilateral cervical sites. Symmetry of the swallowing sounds acquired using our method was verified because no significant differences were found for any parameters in both time and frequency domain analyses between swallowing sounds detected bilaterally. This result supports the use of a “unilateral” site for the detection of swallowing sounds. The reproducibility of swallowing sounds was assessed by a coefficient of variation. Results of this analysis suggest that one should evaluate the acoustic characteristics of swallowing sounds from repeated swallows rather than from one swallow.

Histologic and microradiologic comparison of block and particulate cancellous bone and marrow grafts in reconstructed mandibles being considered for dental implant placement

PURPOSE Patterns of healing were investigated in mandibles reconstructed with three different techniques to assess their readiness for implant placement. PATIENTS AND METHODS The subjects were 10 patients who had undergone mandibular reconstruction with either nonvascularized iliac block bone grafts (group 1; 3 patients), particulate cancellous bone and marrow (PCBM) grafts (group 2; 3 patients) for mandibular discontinuity, or PCBM grafts for mandibular marginal defects (group 3; 4 patients). Six (groups 2 and 3) or 12 months (group 1) after mandibular reconstruction, bone biopsy specimens were obtained for histologic examination with a trephine bur. As controls, bone specimens were obtained from ungrafted mandibles of patients undergoing dental implant placement. Undecalcified specimens were embedded in polyester resin and examined by routine light microscopy and microradiography. RESULTS The morphology of the specimens from group 1 was similar to that of group 2, but not to that of the control subjects. However, the morphology of specimens from group 3 was generally similar to that of control subjects. CONCLUSION These results suggest that mandibular reconstruction with PCBM grafts allows the placement of dental implants sooner than reconstruction with block bone grafts.

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.

Functional effects of intraoral reconstruction with a free radial forearm flap

Summary Postoperative articulation was investigated in patients who underwent glossectomy and reconstruction with free radial forearm flaps. The methods of evaluation consisted of scores for intelligibility of 100 Japanese syllables and 3 groups of glossal sounds. The glossal sounds, based on palato-lingual contact (lingogram), were useful to evaluate function of the respective parts of the tongue. One patient who had had a partial glossectomy and resection of the floor of the mouth achieved an overall score of 80.5% one year postsurgery, and his glossal sounds were also excellent. Three patients who underwent removal of the floor of the mouth and hemiglossectomy, excluding the root of the tongue, had overall scores ranging from 45.6% to 82.1%. Two of these had particularly low scores for the glossal sounds produced with the rear part of the tongue, and this suggested the necessity for suspension slings to prevent depression of the reconstructed tongue and the floor of the mouth. The hemiglossectomy with partial mandibulectomy had an acceptable score of 68.7%. Chronologically, the glossal sounds produced with the rear part and the blade of the tongue often tended to improve postsurgery.

Articulatory Function After Resection of the Tongue and Floor of the Mouth: Palatometric and Perceptual Evaluation

Linguapalatal contact patterns and the time course of changes in contacts during utterances of/asa, ata, a sa, aca/ were measured using electropalatography (EPG). The relations between these data and perceptual scores in 17 glossectomized patients after various surgical methods were examined. The linguapalatal contact patterns produced during perceptually less distorted sounds varied with the place and manner of articulation. Patterns having very few contacts or a posterior groove produced more distorted /s/ sounds; however, types of EPG patterns producing less distorted /s/ sounds were relatively frequent. Distortion of the and /c/ sounds was less often produced by variation of the EPG patterns, whereas /t/ sounds were most frequently judged to be highly distorted. Patterns that showed complete constriction along the dental arch or constriction on the anterior portion of the hard palate, as well as rapid release for plosion by the tongue tip, produced less distorted /t/ sounds. The results revealed that glossectomized patients often evidenced defective stop sounds. It was concluded that mobility rather than volume of the residual tongue is required to produce less distorted stops.