Tsuyoshi Taji

Functional dental occlusion may prevent falls in elderly individuals with dementia

To the Editor: More than one-third of persons aged 65 and older fall each year, and in half, falls are recurrent. The prevention of falls in this growing population is a primary concern for maintaining an adequate quality of life. Elderly persons with cognitive impairment and dementia have two times the risk for falls as cognitively normal elderly persons. It has been demonstrated that multifactorial assessment and intervention focused on these risk factors, including impaired gait and balance (postural instability), environmental hazards, drugs, and cardiovascular diagnoses, has been successful in preventing falls in cognitively normal elderly persons but not in the elderly with cognitive impairment and dementia. It can be hypothesized that primitive reflexes such as postural stability are more important for demented elderly. When in an upright position, permanent oscillations are generated to maintain balance. Sensorial afferents are provided from proprioceptive, tactile, vestibular, and visual receptors. Proprioception of the mandibular system arises from the masticatory muscular system and dentoalveolar ligaments. Poor or absent dental occlusion may decrease proprioception in this area, interfering with the stability of head posture. In this study, the incidence of falls in individuals with adequate dental occlusion is compared with that of those with inadequate dental occlusion. In addition, in a smaller pilot study, the effect of improved dental occlusion on occurrence of falls was investigated in subjects who had previously fallen recurrently. Subjects for this study were 146 ambulatory elderly persons who had been admitted to a special geriatric hospital for individuals with behavior disorders who were also suffering from severe dementia. Inclusion criteria limited subjects to those who could walk, with or without a cane, for all of their ambulation. Multifactorial assessments of each patient’s function, including the Mini-Mental State Examination (MMSE), and pharmacotherapeutic status were performed, and occupational therapists conducted daily group rehabilitations to maintain physical ability. One dentist (MY) classified each subject’s occlusion into one of three categories: Group AFnatural dentition with adequate function, Group BFpartially or fully edentulous but maintaining functional occlusion with dentures in either or both jaws, and Group CFfunctionally inadequate occlusion with no dentures. Subjects were also divided into two groups: the high falls group ( 2 falls during the previous year), and the low falls group ( 1 falls). In a smaller pilot study, denture treatment was provided for a small subgroup of high falls patients who gave informed consent. After denture delivery, the incidence of falls was recorded over 1 year. During the 1-year investigative period, 41 of 146 patients had recurrent falls. No differences between the high and low falls groups in proportion of women (75.6% vs 69.5%), mean age (83.1 6.4 vs 81.9 6.9), use of psychoneurotic medications (56.1% vs 61.9%), or mean MMSE score (9.6 6.7 vs 11.8 6.3) were found. Dental status was significantly different between the high and low groups (Po.001) (Table 1). In the high falls group, 10 patients (2 men and 8 women, mean age standard deviation 81.0 8.0, mean MMSE score 12.1 4.0) who gave informed consent received denture treatment. Conventional denture treatments were provided, and all patients used dentures after treatment. During the investigative period after denture delivery, three patients were excluded because they were comatose or dead. All of the seven remaining patients experienced decreased frequency of falls, with five patients experiencing one or no falls during 1 year of follow-up. Within the limits of this study, it was found that patients with functionally inadequate dental status had significantly more-frequent falls than those with functionally adequate occlusion composed of natural teeth, dentures, or both. Because tooth loss may result in a decrease in proprioception in the masticatory muscles or dentoalveolar ligaments, an associated perturbation of visual stabilization and postural imbalances may be induced. One study indicated that dental occlusal condition is associated with reduced lower extremity dynamic strength, agility, and balance function in elderly people. These findings suggest that functional occlusion of natural or artificial teeth may play an important role in generating an adequate posture reflex through mandibular stability, preventing falls. The current small intervention pilot study, which reconstructed occlusion with dentures, supports these finding. In conclusion, poor or inadequate dental occlusion may be a predisposing factor for falls in older people, and improving occlusion deserves attention as an approach to prevention of falls in elderly patients. A dental examination is recommended for inclusion in the standard health examination for elderly persons, especially those with symptoms of dementia.

Body weight and serum albumin change after prosthodontic treatment among institutionalized elderly in a long-term care geriatric hospital.

OBJECTIVES An important purpose of denture treatment is the improvement of nutritional intake. This is especially important for the dependent elderly who have a high risk of protein-energy malnutrition. To evaluate the impact of denture treatment on such a population, we compared body weight as an indicator of nutritional status before and 6 months after prosthodontic treatment. METHODS This study was conducted in a long-term care geriatric hospital in Hiroshima, Japan from October 2004 to September 2006. One hundred and four patients received complete or partial denture treatment in both jaws. Nineteen patients were lost to the study because of the development of severe physical conditions or death. Among the remaining 85 patients, 66 used their new prostheses and 19 did not. Body weight and serum albumin levels were examined at prosthesis insertion and 6 months after treatment. RESULTS Six months after prosthodontic treatment body weight changes were significantly different between users and non-users regardless of denture type and, in addition, serum albumin level were significantly increased among individuals using partial denture in either or both jaws (P < 0.05). CONCLUSION It can be concluded that prosthodontic treatment may improve the nutritional status of institutionalized elderly.

Dynamic viscoelastic properties of vinyl polysiloxane denture soft lining materials.

The aim of this study was to investigate the dynamic viscoelastic properties of seven commercially available vinyl polysiloxane denture soft lining materials. Five rectangular specimens (2 x 10 x 30 mm) were prepared from each material. The complex modulus E* (MPa) and loss tangent (tan delta) of each specimen were determined with a non-resonance forced vibration method using an automatic dynamic viscoelastometer at 1 Hz after 1 day of dry storage, and after 1, 30, 60, 90 and 180 days of wet storage at 37 degrees C. All data were analysed using one-way anova and Bonferroni/Dunns test for multiple comparisons with a significance level of P < 0.01. All materials varied widely in terms of viscoelasticities and showed both an increase in E* and a decrease in tan delta at 1 Hz after the 1-day wet storage. After 60 days of wet storage, both E* and tan delta did not change significantly. The stiffer materials (>30% filler content) with high E* values (>2.00 MPa) showed elastic behaviour with tan delta values of around 0.03. The softer materials (6% filler content) with high tan delta values (initial value > 0.10) showed viscous behaviour and were easily affected by water absorption after the 1-day wet storage. It can be concluded that for the proper selection of vinyl polysiloxane denture soft lining materials, it is very important to evaluate the viscoelastic properties after 60 days of wet storage.

Bovine milk fermented with Lactobacillus rhamnosus L8020 decreases the oral carriage of mutans streptococci and the burden of periodontal pathogens

AIM   The aim of this study was to find the oral isolate of lactobacilli, which has the potential to inhibit either periodontal, cariogenic, or fungal pathogens in vitro, and to examine the effects of bovine milk fermented with the isolate on the oral carriage of cariogenic and periodontal pathogens. METHODS   The inhibitory effects of the supernatant of Man-Rogosa-Sharpe broth, in which each of 42 oral isolates of lactobacilli grown, was examined. One isolate, Lactobacillus rhamnosus L8020, that showed the potential to inhibit either periodontal, cariogenic, or fungal pathogens in vitro, was used to examine the effects of fermented milk on the oral carriage of cariogenic and periodontal pathogens, which was examined by a placebo-controlled and cohort trial using 50 participants. RESULTS   Edible yogurt containing Lactobacillus rhamnosus L8020 significantly reduced the oral carriage of mutans streptococci (P < 0.01) and four periodontal pathogens examined: Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Fusobacterium spp. (P < 0.01), but the phenomenon were not observed with the placebo yogurt (P > 0.05). CONCLUSION   These results suggest that yogurt with Lactobacillus rhamnosus L8020 could reduce the risk of dental caries and periodontal disease.

Accuracy of a three-dimensional dentition model digitized from an interocclusal record using a non-contact surface scanner

OBJECTIVES For orthodontic treatment, it is important to assess the dental morphology, as well as the position and inclination of teeth. The aim of this article was to develop an efficient and accurate method for the three-dimensional (3D) imaging of the maxillary and mandibular dental morphology by measuring interocclusal records using an optical scanner. MATERIALS AND METHODS The occlusal and incisal morphology of participants was registered in the intercuspal position using a hydrophilic vinyl polysiloxane and digitized into 3D models using an optical scanner. Impressions were made of the maxilla and mandible in alginate materials in order to fabricate plaster models and created into 3D models using the optical scanner based on the principal triangulation method. The occlusal and incisal areas of the interocclusal records were retained. The buccal and lingual areas were added to these regions entirely by the 3D model of the plaster model. The accuracy of this method was evaluated for each tooth, with the dental cast 3D models used as controls. RESULTS The 3D model created from the interocclusal record and the plaster model of the dental morphology was analysed in 3D software. The difference between the controls and the 3D models digitized from the interocclusal records was 0.068±0.048mm, demonstrating the accuracy of this method. LIMITATIONS The presence of severe crowding may compromise the ability to separate each tooth and digitize the dental morphology. CONCLUSIONS The digitization method in this study provides sufficient accuracy to visualize the dental morphology, as well as the position and inclination of these teeth.

A novel strategies for the education of oral engineers

昭和 40 年に全国 3 番目の国立大学歯学部として, 広島大学(同時に東北大学,新潟大学)に歯学部が設 置された.その後,昭和 47 年に附属歯科技工士学校, 昭和 51 年に附属歯科衛生士学校が併設された.これ らの専門学校を基盤として,平成 17 年 4 月,口腔保 健学科口腔保健工学専攻が設置され,口腔保健衛生学 専攻は,前年度設置された東京医科歯科大学,新潟大 学についで全国で 3 番目の設置となり,口腔保健工学 専攻は,歯科技工士教育施設として全国で初めての設 置であった. 平成 21 年 4 月には,大学院口腔健康科学専攻(修 士課程)を設置したが,この時に学年進行の終了した 口腔保健学科を大学院の専攻名称と合わせた形で口腔 健康科学科への名称変更を行った.また,大学院の設 置および学科名の変更に伴い,専攻名を口腔保健工学 専攻から口腔工学専攻にし,人材育成像として従来の 歯科技工士ではなくオーラルエンジニアの育成を行う という教育上の特色を明確化した.同年 4 月には,学 部教育として文部科学省 GP にバイオデンタル教育プ ログラムが採択され,次世代型歯科医療を打ち出すと ともに,歯科医師・歯科衛生士・歯科技工士融合型教育, Interprofessional Education をスタートさせた.平成 23 年 4 月,大学院口腔健康科学専攻(博士課程後期) を設置し,口腔工学という学術分野の構築のために教 育者・研究者の養成を目指す体制ができあがった.