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.     

口呼吸与鼻呼吸儿童牙弓、基骨形态差异的研究

目的：比较口呼吸与鼻呼吸儿童牙弓、基骨形态的差异，探讨呼吸方式与牙弓、基骨形态的关系。方法：通过口鼻气流同步测定系统的随机检测，选择鼻呼吸比例≤70％(口呼吸组)及≥95％(鼻呼吸组)的11～14岁儿童各34人，测量石膏模型，比较其牙弓、基骨形态的差异。结果：①口呼吸儿童与鼻呼吸儿童相比腭盖较高，上颌基骨较窄，形态相对窄长。②口呼吸儿童比鼻呼吸儿童的上颌中、后段牙弓较长，牙弓形态相对窄长，下颌牙弓后段形态也相对窄长。结论：口呼吸可以引起儿童牙弓、基骨形态的改变。     

The effects of fixed and removable implant-stabilised prostheses on posterior mandibular residual ridge resorption

Abstract: This study investigated the change over time in the area of the posterior mandibular residual ridge in patients wearing either i) mandibular overdentures stabilised by two implants (Brånemark System; Nobel Biocare, Göteborg, Sweden) connected by a bar, or ii) mandibular fixed cantilever prostheses stabilised on five or six implants. Proportional measurements were made in order to compare the area of the residual ridge with an area of bone uninfluenced by resorption. Measurements were made by digitising tracings of panoramic radiographs that were taken shortly after implant insertion and up to seven years later. With the use of overdentures, the posterior bone area index reduced by a mean of 1.1% per annum, while a mean bone area index increase of 1.6% per annum was demonstrated in association with fixed prostheses. A multiple linear regression model was fitted to predict the change in posterior area from type of prosthesis, gender, age, years of edentulism and initial height of the mandible. The model was only significant for initial height of mandible (P = 0.04) and type of prosthesis (P = 0.0001). In conclusion, patients rehabilitated with implant‐stabilised mandibular overdentures demonstrated low rates of posterior mandibular residual ridge resorption, while patients rehabilitated with implant‐stabilised mandibular fixed cantilever prostheses demonstrated bone apposition in the same area.     

Modulation of osteogenic potential by recombinant human bone morphogenic protein-2 in human periodontal ligament cells: effect of serum, culture medium, and osteoinductive medium

BACKGROUND AND OBJECTIVE: Bone morphogenic proteins are known, in animal models, to promote many developmental processes, including osteogenesis. Clinical trials are currently underway to evaluate the potential of bone morphogenic proteins to promote bone and periodontal regeneration in humans. The aim of this study was to establish an optimal cell culture condition for using to study the biological effects of recombinant human bone morphogenic protein-2 on periodontal ligament cells. MATERIAL AND METHODS: The roles of serum concentration, types of culture medium (alpha-modified essential medium or Dulbecco's modified Eagle's medium), the presence of osteoinductive medium (including dexamethasone, ascorbic acid and beta-glycerophosphate), and timing of addition of the osteoinductive medium and recombinant human bone morphogenic protein-2, on the expression of alkaline phosphatase were investigated in cultured periodontal ligament cells. Cytochemical stainings and biological assay of alkaline phosphatase were also demonstrated. RESULTS: Our results suggested that an increased concentration of serum might mask the effect of recombinant human bone morphogenic protein-2 on the expression of alkaline phosphatase in periodontal ligament cells. alpha-Modified essential medium was found to induce a stronger cytochemical staining of the alkaline phosphatase than Dulbecco's modified Eagle's medium under similar culture conditions. Pre-incubation of cells with osteoinductive medium before the addition of various concentrations of recombinant human bone morphogenic protein-2 enhanced greater alkaline phosphatase expression than the simultaneous presence of both osteoinductive medium and recombinant human bone morphogenic protein-2. CONCLUSION: The findings of this study suggest that the effect of recombinant human bone morphogenic protein-2 on periodontal ligament cells could be efficiently investigated after the proper selection of culture variables and temporal sequence of adding bioactive factors. The optimal culture condition identified in this study might be useful in further studies to elucidate the regulatory mechanism of periodontal ligament cells in periodontal regeneration after stimulation with recombinant human bone morphogenic protein-2.     

Alveolar bone growth in response to endosteal implants in two patients with ectodermal dysplasia

The occurrence of alveolar bone growth after placement of endosteal mandibular implants in two edentulous children is reported. The fact that alveolar bone growth occurred in the absence of natural teeth suggests that its growth and preservation is dependent upon biomechanical factors rather than the presence of teeth, as is traditionally thought.     

Biologic outcome of single-implant restorations as tooth replacements: a long-term follow-up study

Background: The replacement of a single tooth or several teeth by means of single‐implant restorations is an increasingly used method that needs long‐term validation. Purpose: The goal of this study was to evaluate the outcome of single‐implant restorations by means of fixed restorations and to define the prognosis through marginal bone level estimations. Materials and Methods: From November 1986 to June 1998, 270 Brånemark implants (215 in the upper jaw) were installed in 219 patients (106 males). Both anterior and posterior sites were involved. Of the 263 single restorations, 28 were placed in private dental offices. The patients were followed until June 1999. Results: Twelve implants failed before or at abutment connection or within 6 months afterward. Only four implants failed later. The cumulative success rates were 93% for the implants and 96.5% for the restorations over a period of 11 years. The marginal bone loss during the first 6 months after abutment connection reached 0.71 mm and then dropped to 0.036 mm annually over a period of 10 years. Conclusions: Single‐implant restorations (Brånemark System) are a reliable treatment with a good long‐term prognosis. Failures were concentrated during the healing period and early loading phase.     

大块状生物活性玻璃陶瓷表面复合骨髓-骨松质的成骨作用研究

将自体骨髓-骨松质(ABMC)复合于块状生物活性玻璃陶瓷(BGC)表面，植入12条杂种狗无骨膜的下颌骨缺损区，分别于术后4周、12周、20周和40周处死，采用光镜、荧光显微镜及扫描电镜观察局部新骨生成与改建状况。发现术后4同时植入BGC上面有多量的新生骨形成，随时间的推移，此层骨组织增厚，并从不规则的骨芽向小梁骨转化，沉积在BGC表面或微孔内。而对照组始终末见骨形成。经结果表明BGC可以作为ABMC的生物载体，促进ABMC的异位成骨效应。BGC表面复合ABMC种植改善了BGC的力学强度．扩大了临床应用范围。     

Induction of immune responses and prevention of alveolar bone loss by intranasal administration of mice with Porphyromonas gingivalis fimbriae and recombinant cholera toxin B subunit

INTRODUCTION: Adult periodontitis is initiated by specific periodontal pathogens represented by Porphyromonas gingivalis; however, an effective measure for preventing the disease has not yet been established. In this study, the effectiveness of a vaccine composed of fimbriae of P. gingivalis and recombinant cholera toxin B subunit (rCTB) was evaluated using BALB/c mice. METHODS: Fimbriae and rCTB were co-administered intranasally to BALB/c mice on days 0, 14, 21, and 28. On day 35, mice were sacrificed to determine immunoglobulin levels in serum, saliva, and nasal and lung extracts by enzyme-linked immunosorbent assay. The prevention effect of the vaccine on P. gingivalis-induced periodontitis in mice was evaluated by measuring alveolar bone loss. RESULTS: The rCTB significantly increased serum immunoglobulin (Ig)A levels when mice were administered with a minimal amount (0.5 microg) of the fimbrial antigen. The adjuvant effect on serum IgG production was indistinct because the minimal amount of the antigen still induced a large amount of IgG. In contrast to systemic responses, a fimbria-specific secretory IgA response was strongly induced by co-administration of rCTB and 0.5 microg fimbriae; the same amount of the antigen alone scarcely induced a response. Histopathological examination revealed IgA-positive plasma cells in the nasal mucosal tissue but no observable mast cells in the area. In addition, nasal administration of the fimbrial vaccine significantly protected the mice from P. gingivalis-mediated alveolar bone loss. CONCLUSION: Nasal vaccination with a combination of fimbriae and rCTB can be an effective means of preventing P. gingivalis-mediated periodontitis.     

A comparative study of sialic acid-rich proteins in rat bone and dentin

Four sialic acid-rich (SA-rich) proteins found in bone and dentin, osteopontin (OPN), bone sialoprotein (BSP), bone acidic glycoprotein-75 (BAG-75), and dentin matrix protein 1 (DMP1), share some common features. We used SDS-PAGE and Western immunoblots to analyze and compare SA-rich proteins in bone and dentin extracts from rats with a single chromatographic procedure. OPN was detected in dentin extracts, with a relative level less than one-seventieth of that in bone. Both bone and dentin BSP demonstrated an extremely broad distribution pattern, probably due to a high degree of heterogeneity in post-translational modifications. BAG-75 in both bone and dentin was detected as an 83 kDa band, dramatically distinct from that of DMPI. Using a polyclonal antibody raised against a purified bone 57 kDa protein (a portion of DMPI), we detected 150 kDa protein bands in bone fraction; the same bands were recognized by antirecombinant rat DMPI antibody. Bands from dentin migrating at about 150 kDa in earlier fractions and progressing to 200 kDa in later fractions showed a clear immunoreactivity to the anti-57 kDa antibody. We conclude that the majority of DMPI in rat bone is processed into fragments, whereas that in dentin remains intact.     

人牙周膜细胞中内源性骨形成蛋白的流式细胞仪分析

目的：定量检测和分析人牙周膜细胞（ＰＤＬＣ）表达内源性骨形成蛋白（ＢＭＰ）的情况。方法：应用ＢＭＰ单克隆抗体，通过流式细胞仪和免疫组化ＡＢＣ的方法双重判定。结果：在离体培养的人ＰＤＬＣ中有一半左右的细胞能表达ＢＭＰ。结论：牙周膜细胞具有一定的合成和分泌ＢＭＰ的能力；可以进一步认为人的牙周膜细胞是具有成骨潜能的，在牙周组织再生中有积极作用。