Influence of tooth clench on the soleus H-reflex

The Hoffmann (H) reflex is elicited by electrical stimulation of a mixed nerve and is used to measure the excitability of the spindle-motoneuron synapse. Recent investigations have indicated a positive correlation between increases in bite force and H-reflex facilitation. However, these investigations did not examine the H-reflex in detail or the possible role of periodontal mechanoreceptors (PMRs) in this facilitation. The current investigation was performed to determine whether PMRs play a role in H-reflex facilitation during tooth clench (TC). The H-reflex was elicited in the soleus muscle of human subjects while bite level was maintained at rest (0 N), 40 N, 80 N and maximal TC. The front teeth that contributed to the (40 N and 80 N) bite force were then locally anaesthetised (LA), and the protocol was repeated. The current data suggest that the effect of TC on the H-reflex amplitude in the human limb muscles is variable from one subject to the next. Statistical analysis has shown that the H-reflex was significantly smaller during the rest condition than during the 80 N bite (p<0.05) in both non-LA and LA conditions. Since LA did not alter the response, our results do not support that the PMRs play a major role in the facilitation of distal muscle activity.     

Bone health and oral health

BACKGROUND: Low bone mass in the skeleton, which increases the risk of osteoporotic fracture, also may be associated with periodontal bone loss and tooth loss. Osteoporosis and periodontal disease share several common risk factors, including older age, smoking and perhaps insufficient dietary intakes of calcium and vitamin D. CONCLUSION: Research supports the idea that osteoporosis independently influences alveolar bone height loss. Strategies for reducing osteoporosis risk also may help retard alveolar bone loss. Meeting dietary intake recommendations for calcium and vitamin D is one strategy that is appropriate for a broad segment of the population. CLINICAL IMPLICATIONS: A healthy lifestyle has multiple benefits for the mouth and throughout the body. Dental professionals can play a role in preventing osteoporosis by reinforcing this message.     

可摘局部义齿修复1126例临床分析

目的：对1126例可摘局部义齿进行分析，为临床关于可摘局部义齿修复牙列缺损积累经验。方法：随机选取1126件义齿修复病例，分析牙齿缺损位置、数量与性别和年龄的关系及修复体的类型，并对采用新技术进行的特殊设计进行分析。结果：上颌牙缺失多于下颌，不同年龄组缺牙好发部位不同，青年组以前牙缺失为多，其他年龄组以后牙缺失为多。男女两组中平均失牙数随年龄增加而增加，但与性别无关，在各类可摘局部义齿设计中，第5类最多。结论：可摘局部义齿制作简便，适应症广，目前仍然在修复治疗中发挥着重要的作用。     

Progression of periodontitis in a sample of regular and irregular compliers under maintenance therapy: a 3-year follow-up study

Background: To our knowledge, prospective studies (matched for sex, smoking, and diabetes) that investigated the influence of compliance in the progression of periodontitis and tooth loss in periodontal maintenance therapy (PMT) programs were not previously reported. Methods: A total of 58 regular complier (RC) and 58 erratic complier (EC) individuals were recruited from a prospective cohort with 238 patients under PMT and matched by sex, diabetes, and smoking habits. A full‐mouth periodontal examination that included bleeding on probing (BOP), probing depths (PDs), clinical attachment levels, and number of teeth were determined at all PMT visits during a 3‐year interval. The influence of variables of interest was tested through multivariate logistic regression. Results: The progression of periodontitis and tooth loss was significantly lower among RC compared to EC patients. A higher progression of periodontitis was observed among EC patients who smoked. The final logistic model for the progression of periodontitis in the RC group included smoking (odds ratio [OR]: 4.2) and >30% of sites with BOP (OR: 2.8), and the final logistic model for the progression of periodontitis in the EC group included smoking (OR: 7.3), >30% of sites with BOP (OR: 3.2), PDs of 4 to 6 mm in 10% of sites (OR: 3.5), diabetes (OR: 1.9), and number of lost teeth (OR: 3.1). Conclusions: RC patients presented a lower progression of periodontitis and tooth loss compared to EC patients. This result highlighted the influence of the pattern of compliance in maintaining a good periodontal status. Moreover, important risk variables such as smoking and diabetes influenced the periodontal status and should be considered when determining the risk profile and interval time for PMT visits.     

Traumatic injuries to the primary dentition and effects on the permanent successors – a clinical follow-up study

Abstract –  This study investigated problems in the permanent dentition that, according to history and records, were attributable to dental alveolar injuries of the primary dentition. 106 children have been involved in the study, who had experienced primary anterior tooth trauma affecting a total of 200 teeth. Thirty-nine patients (81 teeth) were available for follow-up examinations. In 25% of the cases followed up, damage was found on the successors in the secondary dentition (16 children/20 teeth). In half of the cases, a comparatively mild form of lesion like enamel discoloration was observed. This was the result of an injury during the tooth maturation process causing enamel hypoplasia. Clinically more relevant were the dental deformities: cessation of root formation or retention caused by ankylosis, which made up the remaining 50% of cases. This was confirmed by clinical long-term observation. The different effects on the permanent teeth can only be detected by radiography after an interval of several months or may even be clinically assessed only after the eruption of the clinical crown.     

Evaluation of physiological tooth movements within clinically normal periodontal tissues by means of periodontal pulsation measurements

The three-dimensional physiological tooth movement synchronized with heartbeat, periodontal pulsation, has already been demonstrated by previous researchers. The purpose of this study was to estimate physiological tooth movements within clinically normal periodontal tissues, thus establishing periodontal pulsation standards. The measuring device consisted of an amorphous sensor and a small magnet, which could detect tooth displacement without coming into contact with the tooth surface. The samples consisted of the left maxillary central incisors of 23 adult subjects. Three points on the labial surface were used as reference points to measure the labial-lingual movement range, and a point on the incisal edge was used for measuring the incisal-apical movement range. Periodontal pulsation and electrocardiogram measurements were recorded simultaneously for six minutes. The results showed that the mean amplitude of periodontal pulsation concerning the labial-lingual movement range was equal at the three labial points (0.59 microm) and tended to be smaller than that of the incisal-apical movement range (0.87 microm). There were no significant differences in the mean amplitude of periodontal pulsation at any of the four reference points. Significant correlations of the amplitude of periodontal pulsation existed among the three labial points. Though most teeth pulsated uniformly to the labial direction, some teeth moved in a complex manner including rotation with an axis among the three labial points. These results suggest that the values of periodontal pulsation amplitude which were recorded employing the amorphous sensor device are reliable standards of periodontal pulsation within clinically normal periodontal tissues.     

Physiological properties of periodontal mechanosensitive neurones in the posteromedial ventral nucleus of rat thalamus

Unitary discharges of periodontal mechanosensitive (PM) neurones responding to mechanical tooth stimulation were recorded from the posteromedial ventral nucleus (VPM) of rat thalamus. PM neurones are distributed in the ventromedial area in the rostral two-thirds of the VPM nucleus. Maxillary and mandibular tooth-sensitive neurones are arranged in dorsoventral sequence. Of the PM neurones, 36% were slowly adapting to pressure applied to the tooth and 67% were rapidly adapting. The majority of PM units were sensitive to the contralateral incisor tooth. Response magnitudes of the slowly adapting neurones varied with stimulus direction and were directionally selective to mechanical tooth stimulation. The optimal stimulus direction was labiolingual or linguolabial. Rapidly adapting neurones were directionally non-selective to tooth stimulation. The threshold for mechanical stimulation was <0.05 N. Mean response latencies evoked by electrical stimulation of the peripheral receptive fields were 4.6 ms in the slowly adapting neurones and 5.8 ms in the rapidly adapting neurones.     

Effects of smoking and drinking habits on the incidence of periodontal disease and tooth loss among Japanese males: a 4-yr longitudinal study

OBJECTIVE: We investigated the risk of periodontal disease and tooth loss, associated with habits of smoking and alcohol consumption, in a longitudinal study. SUBJECTS AND METHODS: The subjects were 1332 Japanese males, 30-59 yr of age, who were free from periodontal disease at the baseline check-up, and who underwent a second check-up 4 yr later. Periodontal disease was diagnosed using the community periodontal index score, based on the clinical probing of pocket depth (> or = 4 mm). Smoking and alcohol consumption patterns were evaluated using a self-administered questionnaire. RESULTS: A dose-response relationship was observed between the amount of smoking and the incidence of periodontal disease in each age group. The overall odds ratios (95% confidence intervals), adjusted for age and alcohol, were 1.51 (0.95-2.22), 1.58 (1.13-2.22) and 2.81 (1.96-4.03), among smokers consuming 1-19, 20 or 21 or more cigarettes per day, respectively, with a significant linear trend (p < 0.0001). A similar association was found between smoking and tooth loss, except for the 50-59-yr-old age group. The adjusted odds ratios were 1.26 (0.60-2.64), 2.01 (1.21-2.32) and 2.06 (1.23-3.48), respectively. A significant linear trend between smoking and tooth loss was also observed (p = 0.01). Ex-smokers showed no significant difference compared with nonsmokers. We also found a significant linear trend between alcohol consumption and tooth loss among 30-39-yr-old subjects, while no relationship was observed between alcohol consumption and periodontal disease. CONCLUSION: Cigarette smoking was found to be an independent risk factor for periodontal disease and tooth loss. Alcohol consumption was a limited risk factor for tooth loss in the younger age group, but was unrelated to periodontal disease. To prevent periodontal disease and tooth loss, health practitioners need to encourage people to stop smoking or not to start.     

半坡博物馆馆藏六千年前人颌骨牙齿的磨耗状况分析

目的:调查六千年前新石器时期古人牙齿的磨耗状况,以探寻牙齿磨耗的规律及其演化发展趋势。方法:观察记录并统计了西安半坡博物馆馆藏76例人头颅骨全部牙齿的磨耗情况,用SPSS 12.0软件对全部的904个牙齿进行了统计学分析。结果:不同磨耗度牙齿的构成比中,2°磨耗的比例最高(37.06%)。左右上下对称牙位牙齿的磨耗基本相同。第一磨牙的磨耗程度最重,第三磨牙的磨耗程度最轻。不同年龄段牙齿磨耗度有显著性差异,随年龄的增长,牙齿磨耗度逐渐加重。每一牙位牙齿平均磨耗度男女性别间无显著性差异(P>0.05)。结论:新石器时代古人牙齿的总体磨耗程度较现代人重。     

年轻恒前牙冠折活髓切断术的临床及组织学研究

目的通过临床和组织病理学研究探讨年轻恒前牙活髓切断术的愈后。方法临床上观察11例露髓冠折的上颌年轻恒中切牙活髓切断术后的牙根形成情况，牙根形成后，行根管治疗术，并对取出的根髓进行常规组织学研究，观察其病理变化。结果所有病例牙根均正常形成，根髓的组织学表现为与正常牙髓相比，出现根髓的退行性变，即成纤维细胞减少，胶原纤维增多，且有的牙髓出现玻璃样变性、钙变和细胞间质的颗粒样变性。结论活髓切断术是年轻恒前牙露髓冠折的首选治疗方法，但在牙根形成后，根髓会出现退行性变，因此，需及时改做根管治疗，为进一步的永久修复做准备。