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.     

Immunization of Macaca fascicularis against experimental periodontitis using a vaccine containing cysteine proteases purified from Porphyromonas gingivalis

INTRODUCTION: Periodontitis is a common infectious disease to which Porphyromonas gingivalis has been closely linked, in which the attachment tissues of the teeth and their alveolar bone housing are destroyed. We conducted a study to determine if immunization using a purified antigen could alter the onset and progression of the disease. METHODS: Using the ligature-induced model of periodontitis in Macaca fascicularis, we immunized five animals with cysteine protease purified from P. gingivalis and used an additional five animals as controls. Alveolar bone loss was measured by digital subtraction radiography. RESULTS: Immunization induced high titers of specific immunoglobuin G serum antibodies that were opsonic. Total bacterial load, levels of P. gingivalis in subgingival plaque and levels of prostaglandin E(2) in gingival crevicular fluid were significantly reduced. Onset and progression of alveolar bone loss was inhibited by approximately 50%. No manifestations of toxicity were observed. CONCLUSIONS: Immunization using a purified protein antigen from P. gingivalis inhibits alveolar bone destruction in a ligature-induced periodontitis model in M. fascicularis.     

正畸治疗与牙周硬组织健康的关系及处理

牙周组织,尤其是牙周硬组织的状况与正畸治疗的进程及疗效息息相关。在正畸治疗前及正畸过程中,口腔临床医师应该全面评估可能出现的影响牙周硬组织的问题。本文就正畸治疗中常见的牙周硬组织问题,包括龈乳头缺失、牙槽骨量不足、骨皮质阻力过大、被动萌出异常的病因及防治展开阐述。     

Topical and intermittent application of parathyroid hormone recovers alveolar bone loss in rat experimental periodontitis

Tokunaga K, Seto H, Ohba H, Mihara C, Hama H, Horibe M, Yoneda S, Nagata T. Topical and intermittent application of parathyroid hormone recovers alveolar bone loss in rat experimental periodontitis. J Periodont Res 2011; 46: 655–662. © 2011 John Wiley & Sons A/S Background and Objective: Periodontitis is characterized by periodontal tissue inflammation and alveolar bone loss. The intermittent administration of parathyroid hormone (PTH), a major regulator of bone remodeling, has been demonstrated to stimulate osteoblastic activity. Although the systemic administration of PTH has been reported to protect against periodontitis‐associated bone loss, the effect of the topical administration of PTH is unclear. In this study, the effect of intermittent administration of PTH on osteoblastic differentiation was examined in cultured calvaria cells and then the effect of topical and intermittent administration of PTH was determined by measuring the recovery of alveolar bone loss after inducing experimental periodontitis in rats. Material and Methods: Alkaline phosphatase activity and bone nodule formation were measured in fetal rat calvaria cells. Experimental periodontitis was induced by placing nylon ligature around rat maxillary molars for 20 d. After ligature removal (day 0), PTH was topically injected into buccal gingiva three times a week for 10 wk. Micro‐computed tomography analysis and histological examination were performed on days 35 and 70. Results: Intermittent exposure of PTH in calvaria cells increased alkaline phosphatase activity and bone nodule formation by 1.4‐ and 2.4‐fold, respectively. Ligature procedures induced marked alveolar bone loss around the molars on day 0 and greater bone recovery was observed in the PTH‐treated rats on day 70. An increase in osteoid formation on the surface of alveolar bone was detected in the PTH‐treated rats. Conclusion: Intermittent treatment with PTH stimulated osteoblastic differentiation in fetal rat calvaria cell cultures, and topical and intermittent administration of PTH recovered alveolar bone loss in rat experimental periodontitis.     

Expression of endothelial adhesion molecules in the alveolar ridge mucosa,gingiva and periimplant mucosa

OBJECTIVES: The purpose of this study was to analyze the expression of adhesion molecules on endothelial cells in the alveolar ridge mucosa, the gingiva and the periimplant mucosa in humans. MATERIAL AND METHODS: Twelve partially edentulous subjects were included in the study. In each subject, one soft tissue biopsy was harvested from the edentulous alveolar ridge mucosa, one from a tooth site and one from an implant site. After 3 weeks of undisturbed plaque accumulation, an additional biopsy was obtained from one tooth and one implant site in each subject. The tissue samples were snap frozen and prepared for immunohistochemical analysis. RESULTS: In the alveolar ridge mucosa, smaller proportions of endothelial cells expressing ICAM-1, ELAM-1 and VCAM-1 were observed than in the gingiva. ELAM-1-positive cells occurred in lower numbers than in periimplant mucosa. After 21 days of plaque accumulation, ELAM-1 was increased in tooth sites, but decreased in periimplant mucosa. CONCLUSION: The results of the present study indicated that the proportions of activated endothelial cells and the extravasation of leukocytes is larger in gingiva and periimplant mucosa than in alveolar ridge mucosa. This might be due to the less permeable keratinized epithelial layer in the edentulous ridge mucosa, which offers proper protection against microbial pathogens. The greater expression of endothelial cell adhesion molecules during experimental gingivitis, compared to periimplant mucositis, may reflect its longer history of repeated antigenic assaults.     

The effect of mineral trioxide aggregate on phagocytic activity and production of reactive oxygen, nitrogen species and arginase activity by M1 and M2 macrophages

AIM: To assess the influence of co-culture with mineral trioxide aggregate (MTA) on phagocytosis and the production of reactive oxygen intermediates (ROI) and nitrogen (NO) species and the arginase activity by M1 and M2 peritoneal macrophages. METHODOLOGY: Cellular viability, adherence and phagocytosis of Saccharomyces boulardii were assayed in the presence of MTA. Macrophages were stimulated with zymosan for ROI assays and with Fusobacterium nucleatum and Peptostreptococcus anaerobius and IFN-gamma for NO production and arginase activity, when in contact with capillaries containing MTA. Data were analysed by T, anova, Kruskall-Wallis and Mann-Whitney tests. RESULTS: M2 macrophages displayed greater cellular viability in polypropylene tubes, greater ability to ingest yeast and smaller production of ROI and higher arginase activity when compared with M1 macrophages. Both macrophages, M1 and M2, presented similar cell adherence and NO production. The addition of bacterial preparations to macrophages interfered with NO and arginase productions. MTA did not interfere with any of the parameters measured. CONCLUSIONS: Phagocytosis and the ability of the two macrophage subtypes to eliminate microbes were not affected by MTA.     

Simultaneous or staged installation with guided bone augmentation of transmucosal titanium implants. A 3-year prospective cohort study

A prospective cohort study of 45 nonsmoking consecutively admitted patients was studied for the treatment outcomes following jaw bone augmentation in conjunction with installment of oral implants. Twenty-eight patients were treated for both bone augmentation and implant treatment simultaneously, while 17 patients were treated with a staged approach with the bone augmentation being performed 6-8 months prior to implant installation. Three months following this, prosthetic reconstructions were incorporated. One year thereafter, baseline data and 3 years after reconstruction, follow-up data were obtained. Moderately low mean scores for the bleeding on probing percentage were found at baseline (24%) and after 3 years of function (17%), while the corresponding values at the implant sites were 40.6% and 52.4%, respectively. However, the modified gingival index (mGI) = 2 was found in only 4.8%, and 6.9% at the baseline and 3-year examinations. Peri-implant Probing depth (PPD) and level of attachment mean values did not vary between baseline and follow-up examinations. Only a small proportion of 1.8% yielded PPD = 6.0 mm after 3 years of function. Radiographic bone level measurements showed that 18.2% of the implants lost 0.5 mm during the observation period. Seventy percent of the sites were considered completely stable. It was concluded that predictable treatment outcomes resulted for oral implant installation combined with or staged after jawbone augmentation. Only 6.5% of the sites had lost 1.5% crestal bone with the staged approach while 14% of the sites had lost 1.5 mm, when the implants were placed simultaneously. This suggests that the staged approach may have a lower risk for greater amounts of crestal bone loss as the simultaneous approach. In general, crestal bone loss encountered in the present study corresponded very well with that reported following placement of the same implant system into nonaugmented bone.     

Prognostic factors for alveolar regeneration: effect of space provision

OBJECTIVES: The role of space provision as an independent prognostic factor for periodontal regeneration remains to be established. The objective of this study was to evaluate the role of space provision on alveolar bone regeneration in periodontal sites. METHODS: Critical size, supra-alveolar, periodontal defects were created in 11 young adult Beagle dogs. Six animals received a porous ePTFE device to provide for space provision. Five animals received sham surgery. The animals were euthanized at 8 weeks post-surgery. A histometric analysis assessed vertical regeneration of alveolar bone and the width of the alveolar crest at the base of the defect. Because of the correlation of within-dog measurements, a mixed model anova/ancova was used to analyse the data. RESULTS: A significant relationship between the width of the alveolar crest at the base of the defect and bone regeneration was observed with no significant difference between sites receiving the different treatments (p=0.84). Bone regeneration at sites treated with the space-providing device was significantly greater compared with that at sites treated with sham surgery (p=0.0003), and the difference remained significant after adjusting for bone width (p=0.0001). CONCLUSIONS: Space provision has a significant effect on alveolar bone regeneration in periodontal sites. The width of the alveolar bone appears to influence space provision effectively supporting bone regeneration.     

牙周炎患者拔牙创骨密度变化的测量分析

目的 探讨因牙周炎拔牙后牙槽骨骨密度的变化。方法 采用双能X线吸收法测量不同原因拔牙后牙槽骨骨密度有腰椎椎体骨密度。结果 牙周炎组牙槽骨骨密度变化值低于非牙周炎组；牙周炎患者腰椎椎体骨密度与非牙周炎患者腰椎椎体骨密度无显著性差异。结论 牙周炎患者拔牙后牙槽骨整合速度低于非牙周炎者的愈合速度，这是由于局部炎症的持续作用造成的，全身骨密度状况并不是影响牙周炎的主要因素。     

利用阻生智齿预备钛金属冠改善下颌义齿固位的应用观察

目的:利用阻生智齿增加下颌单颌总义齿固位力。方法:通过手术暴露下颌阻生智齿,在智齿冠上预备牙体,制作钛金属套冠将阻生齿牙冠形态转移至口腔中,从而把固位力不足的下颌单颌总义齿修复,转变成有正常基牙固位的可摘局部义齿修复。结果:通过3例利用埋伏阻生智齿接钛金属套冠,对下颌牙槽嵴严重吸患者的可摘局部义齿修复,经2～3年的临床观察,钛套冠固定良好,无松动,牙龈正常。可摘局部义齿固位良好。结论:利用埋伏阻生智齿接钛金属套冠,加强下颌牙槽嵴严重吸收可摘局部义齿固位力的效果明显。