Stress distribution of abutments and base displacement with precision attachment- and telescopic crown-retained removable partial dentures

Five types of removable partial dentures (two attachment dentures, two telescopic dentures and one clasp denture) were designed. The two attachment dentures were retained by the rigid-precision attachments with or without a stabilizing arm, and the two telescope dentures were retained with cone telescope crowns with or without cross-arch stabilization. The stresses acting on abutment teeth and denture bases and the movements of denture bases were investigated, and the influences of denture design were clarified. The stress acting on a terminal abutment tooth retained by a rigid-precision attachment or cone telescopic crown was larger than that acting on a terminal abutment tooth retained by a clasp. The attachment dentures tended to concentrate more stress at the terminal abutment tooth than did the telescopic dentures. The stress of denture base of an attachment denture and a telescopic denture was less than that of a clasp denture. There was no difference between the stresses of attachment and telescopic dentures. The displacement of the denture base tended to be less when the denture was designed with a rigid connection for the retainer and with cross-arch stabilization.     

牙周病患牙根面的细胞附着和细胞扩展

目的：研究人牙周膜成纤维细胞(PDL)对牙周病患牙和健康牙牙根面的早期附着和扩展，以及脂多糖(LPS)对其的可能作用。方法：收集和制备22例牙周病患牙牙根组织切片，20例健康牙牙根组织切片。PDL取自健康的牙周膜。将培养的PDL接种于牙根组织切片，孵育lh37℃，作细胞计数，检测细胞的早期附着；接种培养的PDL于牙根组织切片，孵育48h37℃检测细胞扩展。用血细胞计数器计数扩展细胞。用涂布LPS的组织培养孔试验LPS对细胞附着、细胞扩展的影响。结果：人牙周膜成纤维细胞在牙周病患牙和健康牙牙根表面的早期附着没有差异，而两者间细胞的扩展有显著差异，健康牙高于患牙。患牙根面的LPS可能是抑制根面细胞扩展的因素之一。结论：牙周病患牙和健康牙的根面均可发生PDL的早期附着，但随着时间的推移，患牙根面的细胞不能发生扩展。     

应用精密附着体修复单侧游离缺失的临床观察

目的：对多个磨牙游离端缺失后应用精密附着体进行单侧修复设计进行临床观察，探讨其修复效果。方法：采用Bredent SG Vario Snap附着体，为38例多个磨牙游离端缺失的患者，制作38件精密附着体义齿，临床随访0．5～4年，分别从主观感觉、口腔检查和X线检查等三方面观察其修复效果。结果：患者进行单侧修复设计后美观效果满意，异物感小，不影响发音，固位稳定效果好，其中31例与以前的双侧修复设计相比，明显感觉较以前舒适，修复效果满意；3例患者在义齿使用1年或3年后附着体活动部分咬合面断裂；34例患者基牙无病变，义齿受力区牙槽嵴黏膜无红肿、压痛。4例患者的远中基牙牙槽嵴顶吸收，硬骨板消失。结论：应用精密附着体对多个磨牙游离端缺失进行单侧设计，具有可实施性。     

Smoking, a weak predictor of periodontitis in older adults

BACKGROUND: The impact of smoking habits on periodontal conditions in older subjects is poorly studied. AIMS: To assess if a history of smoking is associated with chronic periodontitis and medical history in older subjects. MATERIAL AND METHODS: The medical and dental history was collected from 1084 subjects 60-75 years of age. Smoking history information was obtained from self-reports. Periodontal variables [clinical probing depth (PD)>/=5.0 mm, clinical attachment levels (CALs) >/=4.0 mm], and radiographic evidence of alveolar bone loss were assessed. RESULTS: 60.5% had never smoked (NS), 32.0% were former smokers (FS) (mean smoke years: 26.1 years, SD+/-13.1), and 7.5% were current smokers (CS) (mean smoke years 38.0 years, (SD+/-12.1). The proportional distribution of CAL >/=4.0 mm differed significantly by smoking status (NS and CS groups) (mean difference: 12.1%, 95% confidence interval (CI): 1.5-22.6, p<0.02). The Mantel-Haenszel common odds ratio between smoking status (CS+FS) and periodontitis (>20% bone loss) was 1.3 (p<0.09, 95% CI: 0.9-2.0) and changed to 1.8 (p<0.02, 95% CI: 1.3-2.7) with 30 years of smoking as cutoff. A weak correlation between number of years of smoking and CAL>/=4.0 mm was demonstrated (r(2) values 0.05 and 0.07) for FS and CS, respectively. Binary logistic forward (Wald) regression analysis demonstrated that the evidence of carotid calcification, current smoking status, gender (male), and the number of remaining teeth were explanatory to alveolar bone loss. CONCLUSIONS: A clinically significant impact on periodontal conditions may require 30 years of smoking or more. Tooth loss, radiographic evidence of carotid calcification, current smoking status, and male gender can predictably be associated with alveolar bone loss in older subjects.     

Smoking as a risk indicator for periodontal disease in the middle-aged Vietnamese population

BACKGROUND: Studies from developed countries have found smoking a significant risk indicator for periodontitis. However, few such studies have been conducted in developing populations, where the natural history of the disease is rarely confounded by treatment and smoking is highly prevalent. AIM: The present study aimed to confirm the consistency, strength and dose-response of the association of smoking with periodontitis measured by loss of attachment (LOA) in a representative middle-aged adult sample from a developing country. METHODS: A cross-sectional study with a multistage stratified random sample was conducted in two provinces of Vietnam. RESULTS: A total of 575 (response: 84.6%) 35-44-year-old subjects were interviewed and periodontally examined. Data were re-weighted to represent the population of the provinces. 28.9% were current smokers (CS), 8.6% former smokers (FS) and 62.5% never-smokers (NS). Number of cigarette pack-years was calculated to divide CS into light smokers, LS < or = 5 pack-years, and heavy smokers, HS 5+ pack-years. The US NIDR protocol was employed for LOA measurement at two sites per tooth for every tooth. HS presented with the highest prevalence of LOA exceeding various thresholds followed by LS (chi2, P < 0.001). The extent of sites with LOA > or = 4 mm and LOA > or = 6 mm was significantly higher among HS and LS compared to NS (ANOVA; P < 0.001). The severity scores of LOA for NS, FS, LS and HS were 2.42, 2.50, 2.64 and 3.05 mm respectively (ANOVA; P < 0.001). Disease cases were defined as having 2+ sites with LOA > or = 5 mm and 1+ site with PD > or = 4 mm. Compared to NS, the odds ratio for periodontitis among heavy smokers was 7.17 (CI: 2.87-17.92, P < 0.001). CONCLUSION: Smoking is a risk indicator for periodontitis among the middle-aged Vietnamese population. To pursue a population prevention approach for periodontitis, dentistry in Vietnam needs to be part of antismoking and smoking cessation programs.     

The extent and nature of dental fear and phobia in Australia

Background: For the general dental practitioner, fearful patients are harder and more stressful to treat and are most likely to attend irregularly. This study presents updated and refined dental fear and phobia prevalence estimates in Australia as well as information on the nature of dental fear and phobia. Methods: A total of 1084 Australian adults (response rate = 71.7%) completed a mailed questionnaire. The survey contained four measures of dental fear and phobia, as well as questions regarding potentially anxiety‐eliciting dental stimuli and past aversive dental experiences. Results: The prevalence of high dental fear ranged from 7.8% to 18.8%, and more incapacitating dental phobia from 0.9% to 5.4%, depending upon the scale, cut‐point and specific criteria used. Dental phobia was significantly associated with blood‐injection‐injury (BII) concerns. The cost of dental treatment was endorsed as the most anxiety‐eliciting dental situation (64.5%), followed by fear of needles/injections (46.0%) and painful or uncomfortable procedures (42.9%). Anxiety‐eliciting stimuli and the type of aversive dental experiences varied significantly by gender, age, income, education, language spoken at home and dental visiting frequency. Conclusions: High dental fear and dental phobia are common in Australia although prevalence estimates are highly dependent on both the scale and cut‐points used.     

A Rationale For Not Connecting Implants to Natural Teeth

When restoring partially edentulous arches with implants, there are some practitioners who believe it is occasionally beneficial to connect implants to natural teeth. This connection is performed to gain shared support from the natural tooth and implant, prevent rotation of the restoration, or sometimes merely to retain the natural tooth. A discussion and review of the literature concerning this connection is presented, and a patient treatment is shown to illustrate potential complications.     

Parallel bonded cast attachments for removable partial dentures

The original design of a semi-precision extra-coronal attachment for partial dentures is illustrated, and its fabrication in a cast non-precious bondable alloy is described. A step-by-step method is also described of bonding multiple attachments in parallel for the retention and support of removable partial dentures. Clinical cases are illustrated. The results of trials indicate that the method is clinically viable and, in selected cases, appears to offer distinct advantages over existing retention systems.     

New attachment following surgical treatment of human periodontal disease

Abstract The present experiment was undertaken to test the hypothesis that new connective tissue attachment may form on a previously periodontitis involved root surface provided cells originating from the periodontal ligament are enabled to repopulate the root surface during healing. A mandibular incisor with advanced periodontal disease of long standing (the distance between the cemento-enamel junction and the alveolar bone crest was 9 mm) was subjected to periodontal surgery using a technique which during healing prevented the dentogingival epithelium and the gingival connective tissue from reaching contact with the curetted root surface. Preference was hereby given to the periodontal ligament cells to repopulate the previously diseased root surface. After 3 months of healing a block biopsy containing the incisor and surrounding tissue was sampled. The histological analysis revealed that new cementum with inserting principal fibers had formed on the previously diseased root surface. This new attachment extended in coronal direction to a level 5 mm coronal to the alveolar bone crest. This finding suggests that new attachment can be achieved by cells originating from the periodontal ligament and demonstrates that the concept that the periodontitis affected root surface is a major preventive factor for new attachment is invalid.     

Pediatric patients' orthodontic treatment need, quality of life, and smiling patterns -- an analysis of patient, parent, and provider responses

Objectives: The objectives of this study is to explore the relationship between pediatric patients' orthodontic treatment need, the patients' assessments of their smile‐related quality of life (QoL), their parents' proxy assessment of their child's QoL and own assessments of their child's smile, and the patients' objectively assessed smiling patterns. Methods: Survey data were collected from 102 patients (53 boys/49 girls; age range: 9–13 years) and their parents. Orthodontic treatment need was assessed with the Index of Complexity, Outcome, and Need (ICON). Smiling patterns were determined by videotaping patients' smiles while they watched a cartoon. Thirty predetermined sections of these tapes were then assessed by two independent raters to measure the patients' smiling patterns. Results: The aesthetic component and total ICON scores correlated with the patients' smile‐related QoL (r = 0.25; P = 0.014/r = 0.23; P = 0.024), parental proxy assessments of the child's smile‐related QoL (r = 0.29; P = 0.004/r = 0.26; P = 0.009), the parents' own assessments of their child's smile (r = 0.32; P = 0.002/r = 0.29; P = 0.005), and the number of negative adjectives chosen by the parents to describe their child's smile (r = 0.32; P = 0.002/r = 0.30; P = 0.004). Although the smiling patterns were correlated with the patients' smile‐related QoL responses (height of smile: r = 0.29; P = 0.005/number of teeth shown: r = 0.30; P = 0.004), the ICON scores were not correlated with the patients' smiling patterns. Conclusions: Objectively assessed orthodontic treatment need correlates with the patients' and parents' assessments of the child's smile‐related QoL scores. However, while objective smiling patterns are related with the patients' smile‐related QoL, they are not correlated with the patients' orthodontic treatment need.