Kyoko Ikawa

OPTICAL CHARACTERISTICS OF HUMAN EXTRACTED TEETH AND THE POSSIBLE APPLICATION OF PHOTOPLETHYSMOGRAPHY TO THE HUMAN PULP

In order to record pulp blood flow by photoplethysmography, the light transmission properties of extracted human teeth and human peripheral blood at wavelengths between 400 and 800 nm were first investigated. Transmission through peripheral blood and extracted teeth was lower at wavelengths shorter than 600 nm. Transmitted-light photoplethysmography (TLP) was applied to teeth in situ using a tungsten light, or one of two light-emitting diodes (LED) with peak wavelengths of 565 and 695 nm. A CdS-CdSe photoconductive cell was used as a detector. The LED with a peak intensity at 565 nm was the most efficient of the three light sources for recording the TLP. The results indicate that the TLP could be used to assess pulp vitality.

The effects of thermal and mechanical stimulation on blood flow in healthy and inflamed gingiva in man

The purpose of this study was to compare the state of the microcirculation in healthy gingiva with that in untreated, inflamed gingiva in humans. Reflection photoplethysmography (RP) was used to record blood flow from 13 clinically healthy, attached gingival sites in seven adults and 11 inflamed sites in seven patients. Changes in the pulse amplitude of the RP signal were measured before and after application of thermal (cold and hot water) and mechanical (brushing) stimuli to the gingiva. Hot water and brushing, but not cold water, produced a significant increase in the pulse amplitude in healthy gingiva (p < 0.05, Friedman analysis and Student-Newman Keuls test). None of the stimuli produced a significant change in inflamed gingiva. In neither group of participants was there a significant correlation (Spearman rank correlation coefficient) between vascular responsiveness and age. The results indicated that vasomotor control may be impaired in inflamed gingiva.

Tonometric measurement of the gingiva in young and elder humans

We have already reported the hardness of the gingiva in young human subjects measured by a tonometer. In this study, the age-related changes in the hardness of the human gingival tissue were examined. The measurement was made on the young and the elder people who had clinically healthy gingival tissue using a tonometer. The labial surfaces of attached gingival site were selected as examination sites. The gingiva was significantly harder with elder subjects than the young subjects. The results indicated the age-related changes of gingival hardness.

A new intra-oral pressure monitor for screening swallowing dysfunction

Swallowing, which is important for eating and drinking for survival, is one of the basic functions of the mouth. The purpose of this study was to develop a safe and easily-handleable measuring device to evaluate swallowing processes in younger generations. An intra-oral pressure-measuring device estimated the intra-oral positive and negative pressures produced by sucking or blowing. The results indicated that the maximal positive pressure or minimal negative pressure increased or decreased depending upon age. This suggests that the function to produce intra-oral negative pressure, which was made with lip and faucial isthmus closure for sucking, and positive pressure, which was made with lip closure for blowing, was developed with age or physical strength. This simple measuring system of oral pressure was useful in fieldworks for screening oral dysfunction among all generations, not depending upon the condition of tooth or dentition.

Difference between age generation of oral health examination in a rural town

Oral health examinations were held in summer continuously for 2 years with general health checks in a rural town. We included oral health check, practice of oral cleaning, and measurement of oral malodor in the examination. Aim of this study was to examine the difference of impression in the oral health examination between younger and older participants by questionnaires. No difference was found between male and female ratio in each generation. Also, no difference was seen as for ratio of joiners of oral cleaning and ratio of their satisfaction after the practice. Significant difference between two generations was seen as for strong satisfaction ratio with explanation about the result of oral malodor, and effective motivation ratio for oral hygiene caused by measurement of oral malodor. The oral health examination held with general checks with measurement of oral malodor seemed more impressive to older generation.

Dental examinations for oral health promotion in a rural town

We carried out residents-attractive dental health examinations by increasing the learning contents with systemic health examination of a rural town in Japan. Town staffs or some residents who had finished training programs participated in the dental examinations as staffs. Oral malodor was measured to motivate oral hygiene of examinees. We prepared questionnaires and asked the impression of examinees about “the dental examination with learning” 7 months after the examination. Questionnaires showed that 85% of dental examinees recognized it as satisfactory. This fact indicates the possibility that the new dental examination can be a model for oral health promotion in the community.

The TUCL probe for easy learning of probing manipulation

It takes time to learn accurate probing skills, because it is difficult to minimize inherent probing measurement error. Thus, we invented the Tohoku University-type constant load periodontal probe (TUCL probe) to standardize the probing measurements. The TUCL probe gives constant probing force by itself. In this study, we reported the application of the TUCL probe in the training of the probing operation. The probing forces of 60 new dental hygienist students were recorded before and after the practice by using conventional probe and weighing scale, or TUCL probe. For learning the force for probing, 36% of students reported that the TUCL probe was an easier learning tool, compared to the weighing scale. In conclusion, the TUCL probe is a significantly useful instrument, not only for standardizing probing measurement, but also for probing operation training.

Pressure measurement of human gingiva by tonometer

In the present study, we examined the applicability of tonometer to evaluate the hardness of human gingival tissue. For this purpose, induction-based impact method for measuring intraocular pressure was applied. The measurement was made on the young male subjects (n = 7, aver. 24.8 years) who had clinically healthy gingival tissue. The labial surfaces of attached gingival site between teeth were selected as examination. The gingival pressure ranged between 18 and 77 (n = 70, mean ± SD; 44.4 ± 8.1 mmHg). The results indicated that tonometric measurement of the gingival tissue could give quantitative information of the gingival inflammation.

Psychological characterization of halitosis patients by using Egogram and the Halitosis Scale Questionnaires

Halitosis is a common oral concern and patients often seek help from dentists. The purpose of this study is to evaluate psychological characteristics of halitosis patients and their changes with treatment. The subjects consisted of 150 halitosis patients and 64 non-halitosis patients. They were requested to complete Egogram and the halitosis scale questionnaires, before and after treatment. The results indicated that halitosis patients improved in the objective recognition of their malodor level, their obsession with halitosis, and interpersonal communication after treatment. Therefore, the ideal dentist attitude for halitosis treatment is to help patients overcome their obsession by examining their breath level repeatedly and encourage them to develop social skills. However, these subjects had a tendency for social phobia, and its removal was not easy. Therefore, it would be essential that dentists continue to accept their complaints and relapse of their obsession with bad breath sincerely.