Lower Alveolar Ridge Research Articles

The Distinctness of Speakers' /s/—/∫/ Contrast Is Related to Their Auditory Discrimination and Use of an Articulatory Saturation Effect

This study examines individual differences in producing the sibilant contrast in American English and the relation of those differences to 2 speaker characteristics: (a) use of a quantal biomechanical effect (called a "saturation effect") in producing the sibilants and (b) performance on a test of sibilant discrimination. Twenty participants produced the sibilants /s/ and /S/ in normal-, clear-, and fast-speaking conditions. The degree to which the participants used a saturation effect in producing /s/ and /S/ was assessed with a custom-made sensor that measured contact of the underside of the tongue tip with the lower alveolar ridge; such contact normally occurs during the production of /s/ but not /S/. The acuteness of the participants' discrimination of the sibilant contrast was measured using the ABX paradigm and synthesized sibilants. Differences among speakers in the degree of acoustic contrast between /s/ and /S/ that they produced proved related to differences among them in their use of contact contrastively and in their discriminative performance. The most distinct sibilant productions were obtained from participants who used contact in producing /s/ but not /S/ and who had high discrimination scores. The participants who did not use contact differentially when producing the 2 sibilants and who also discriminated the synthetic sibilants less well produced the least distinct sibilant contrasts. Intermediate degrees of sibilant contrast were found with participants who used contact differentially or discriminated well. These findings are compatible with a model of speech motor planning in which goals for phonemic speech movements are in somatosensory and auditory spaces.

The relationship between wearing complete dentures and swallowing function in elderly individuals: a videofluorographic study

The role of complete dentures in masticatory function is well established, but their effect on swallowing has been little examined. This study investigated the effect of complete dentures on swallowing in the elderly. Lateral projection videofluorography (VF) was performed for nine healthy edentulous elderly volunteers (mean age 73.9 +/- 2.9 years) while they swallowed 8 ml of liquid and paste barium with and without complete dentures. A total of 35 VF records were analyzed for temporal and spatial measurements of oropharyngeal motion during swallowing. The tongue tip contacted the inside of the lip between the upper and lower alveolar ridges during swallowing without but not with complete dentures. The hyoid moved further upward (P = 0.002) during swallowing without dentures (liquid: 5.85 +/- 3.99 mm, paste: 6.41 +/- 5.25 mm) than with dentures (liquid: 3.70 +/- 4.57 mm, paste: 3.69 +/- 4.07 mm). The larynx moved further forward (P = 0.044) during swallowing without dentures (liquid: 6.39 +/- 2.58 mm, paste: 6.46 +/- 2.87 mm) than with dentures (liquid: 5.34 +/- 2.04 mm, paste: 5.93 +/- 1.50 mm). The timing of the movements of these structures was not affected by the presence of the dentures or bolus consistency. These results showed that the hyoid and larynx moved more in swallowing without than with complete dentures, perhaps because of tongue tip protrusion when not wearing dentures. These findings suggest that complete dentures have a significant effect on swallowing function as well as masticatory function in elderly individuals.

義歯床下粘膜への負担圧分布からみた選択

In case of making complete dentures, we have to consider not only denture stability but also the restoration of aesthetics and function such as mastication and speech. However these are contradictory theoretically from the point of view of denture stability, and it is very difficult to satisfy both requirements in the case of a patient who has poor upper and lower alveolar ridges. We investigated the effect of artificial posterior teeth form and occlusal scheme on the distribution of pressure on supporting structures under complete dentures during mastication with upper and lower edentulous simulators. In this report, a guideline for the selection of occlusal scheme for complete dentures, based on our previous investigations, is described. The occlusal scheme remarkably affected the distribution of pressure under simulated complete dentures, as shown by comparing the distribution of pressure using two different occlusal schemes:fully balanced occlusion and lingualized occlusion. However other factors such as posterior teeth form and position affect the distribution of pressure as well, and are related to each other. Therefore, not only occlusal scheme but also posterior artificial teeth form has to be considered, and the form of posterior teeth should be carefully and comprehensively decided when making complete dentures.

画像処理装置による人工歯排列位置の診断法について

The purpose of this study is to apply an image analysing system to making a diagnosis of the position of the artificial teeth on edentulous casts in the procedure of complete denture fabrication. Both the upper and lower casts, with the outline of denture base and the line drawn along the center of posterior ridge, were mounted by the split cast method on the average value articulator which had the reference lines for surperimposing some images. And then the artificial teeth were set up in the wax rim on these casts. Two kinds of images about both the casts themselves and the wax dentures on the casts were taken by color camera in the conditions of being removed from the articulator and mounted on it. We could examine the relation of horizontal position between the upper and lower alveolar ridges, and also the horizontal position of the artificial teeth on each upper and lower cast.As a result, it was concluded that the image analysing system was useful to set upcorrectly the artificial teeth on the edentulous casts in complete denture fabrication.

Radiation therapy of squamous carcinoma of the floor of mouth and the lower alveolar ridge.

Treatment for 139 patients with squamous carcinomas in the floor of mouth and the lower alveolar ridge, which accounted for one-third of all patients with intra-oral cancer, are evaluated and classified after UICC and AJC's TNM recommendations retrospectively, for cancer staging and End Result Reporting. The figures include 50% women with tumours and in lower alveolar ridge. Two treatment schemes: external cobalt irradiation and external irradiation in combination with intra-oral radium-mould have been used in spite of primary bone invasion. 30% had remnant tumours and 22% recurred locally. 70% of the recurrences were discovered within a year after treatment. The total crude survival for all patients was 32%, identical for both groups. Lymph node metastases lower the survival significantly. Less than one-third had difficulties in mucous healing after treatment and 9% developed osteoradionecrosis, but only half of those patients had symptoms.

筋圧維持法(いわゆるフレンジテクニック)を応用した無口蓋総義歯の 4 例について

Dentists have been interested in the necessity of palatal plate in complete denture for many years. In 1956, M. Yasaki discussed the retention of roofless denture in his paper and explained the clinical precedure of it's denture. But as it is the fact that the palatal plate has important role in denture retention, the manually formed roofless denture has insufficient retention. Therefore it cannot be used as well as an ordinary complete denture. To increase the retention, T. Kobayashi used implant button technique, R. Akiyoshi utilized soft material to the denture border for peripheral seal and H. K. Kubari recommended functional vacuum method. Two or three years ago, we have had four roofless complete denture cases used flange technique and the prognosis of these dentures were favorable except the case had extremely vomiting reflection. From the result of the above-mentioned four cases, we found that the flange technique was useful for denture retention when the patient had a verious functional movement. It will be necessary to fulfill the following points in order to success in roofless denture. 1. Location and form of the denture border and primary supporting surface must be made functionally by use of dynamic impression. 2. It is necessary that the polishing surface is made by flange technique or any other techniques to increase the retention. 3. Bite taking permits of no error. 4. Arrangement of artificial teeth and contact relation of upper and lower teeth should be performed accurately. 5. Automatic grinding must be used to obtain the full balanced occlusion. 6. In a case of flabby gum on the alveolar ridge especially upper and lower anterior region, and or extremely and expansive resorption of alveolar bone, roofless denture is not adapted satisfactorily. 7. It is desirable that the shape of upper and lower alveolar ridge has not so much difference to each other.

Two cases treated with 800 kv and 400 kv, respectively.

As my contribution to this Symposium, I shall present 2 cases, one of oral carcinoma and one of carcinoma of the cervix, representing different indications for therapy. Case I: A 65-year-old male was seen in October 1950, in excellent general condition, but with an extensive primary epidermoid carcinoma, Grade II, involving the right lower alveolar ridge throughout its length, with infiltration of the entire right floor of the mouth and right gingivobuccal sulcus and a large metastatic submaxillary lymph node open and draining to the skin (Fig. 1). There was roentgen evidence of destruction of the right side of mandible for a distance of 2.5 cm. (Fig. 2). No previous irradiation had been given. The patient was edentulous. Irradiation with 800 kv (h.v.l. 3 mm. Pb) was given through a single right mandibular and submaxillary field of 6 × 7.5 cm., to include the primary carcinoma and the right submaxillary metastasis. In thirty-seven days 6,035 r (measured on skin) was given through this field; the minimal dose to the deepest portion of the growth at the junction of the floor of the mouth and the tongue was 4,800 r. The skin reaction was no more than an erythema, and the anticipated membranous reactions of the right buccal wall, floor of the mouth, and right lateral border of the tongue were well tolerated. Observation over a three-month period following irradiation showed continued regression of the soft-tissue disease of the oral cavity, with a remnant of infiltration at the posterior margin of the buccal wall where it joined the vertical ramus of the mandible; apparently complete resolution of the disease in the gingivobuccal sulcus; closure of the draining sinus and palpable resolution of the metastatic lymph node. Three months after completion of irradiation, surgery was performed by Dr. Frank Wana-maker, consisting in segmental resection of the horizontal ramus of the mandible, together with adjacent soft tissues of the buccal wall, and unilateral suprahyoid neck dissection. The tissues healed well, with good functional result. Pathologic studies showed residual epidermoid carcinoma only in the soft tissue at the site of the local remnant of infiltration of the buccal wall. No evidence of residual cancer was found in the submaxillary tissues or mandible. The patient has remained well over five years, without sequelae secondary to irradiation and with a satisfactory functional result (Fig. 3). Supervoltage irradiation was chosen for this patient for the following reasons: (1) the desirability of irradiating the primary lesion and its metastatic focus through a single field, (2) the necessity of irradiating a mandible already compromised by infiltration of carcinoma, (3) the requirement of penetration through the mandible to reach adjacent soft tissues, and (4) the planning of later surgery within the field of irradiation, making it desirable to obtain conditions which would not too severely compromise radical surgery and healing.