钛种植体表面微结构对成骨细胞影响的研究进展

钛种植体表面形貌是钛种植体表面改性的研究热点之一。种植体表面形貌主要有光滑、粗糙和多孔结构3类。种植体表面形貌对种植体一骨界面的成骨活性产生不同的影响。本文综述了种植体表面微结构对种植体一骨组织界面成骨细胞的生物学行为的影响，为研究和设计种植体表面微结构提供参考。     

牙龈卟啉单胞菌内毒素对成纤维细胞在纯钛表面附着的影响

目的：研究牙龈卟啉单胞菌内毒素对纤维细胞在纯钛表面附着的影响。方法：通过对种植体周围牙龈卟啉单胞菌内毒素脂多糖的提取、鉴定以及对成纤维细胞的作用,同时结合光镜及电子显微镜观察与统计分析。结果：发现成纤维细胞在牙龈卟啉单胞菌内毒素作用下在纯钛表面生长形态改变,趋动附着能力降低。结论：牙龈卟啉单胞菌内毒素具有抑制成纤维细胞在纯钛表面附着的作用。     

Influence of the Residual Ridge Widths and Implant Thread Designs on Implant Positioning Using Static Implant Guided Surgery

Purpose

Aggressive implant macrothread designs have been widely used. However, the effects of the aggressive thread design on the accuracy of static guided surgery, especially in a case of narrow residual ridge, have not been well-studied. The aim of this study was to evaluate the effects of two different implant macrothread designs and the residual ridge widths on the accuracy of tooth-supported static guided implant surgery.

Materials and methods

Forty implant fixtures with two different macrodesigns: a conventional thread design bone level tapered (BLT), and an aggressive thread design bone level tapered (BLX) were placed in 40 simulated polyurethane models with narrow and wide residual ridges. The placed implant positions were compared with the planned implant position and angulational deviation, as well as three-dimensional (3D) deviations at the entry and apex of the implant were measured. One-way ANOVA with Tukey's multiple comparisons (ɑ = 0.05) were used to determine level of significance between the mean and variance deviation values. 95% confidence intervals and box plots were used to demonstrate the means and ranges of precision.

Results

In terms of angulational deviation, there was no statistically significant difference in the mean deviations for both types of implants, p = 1.55 and p = 0.84 for wide and narrow ridge groups, respectively. However, the range of deviation was much larger in the narrow ridge of the BLX group compared to the BLT group. In both narrow ridge and wide ridge, the BLX group had lower mean 3D deviation values at both the entry and the apex with statistically significant differences for both entry point of the wide ridge (p = 0.027) and narrow ridge (p = 0.022) as well as at the apex of the wide ridge (p = 0.006) but not the apex of the narrow ridge (p = 0.142).

Conclusion

The aggressive larger thread design of dental implants may influence the accuracy of implant placement more than the ridge dimension.     

Prosthodontic Management of a Combination Transosteal/ Endosteal Implant Reconstruction: A Clinical Report

This is a clinical report of a patient who was not referred for prosthodontic evaluation and treatment until after undergoing Bränemark endosseous implant placement to supplement the previously existing mandibular staple bone plate implant. This supplemental treatment was the surgeon's attempt to resolve the patient's complaint of loose dentures. Creativity with implant biomechanics and prosthodontic design were necessary to restore the patient, in a predictable manner, to normal function. A fixed, detachable cast overdenture bar rigidly connected to all the implants was constructed utilizing resilient attachments to retain the tissue-supported mandibular overdenture. A presurgical prosthodontic evaluation could have averted many of the problems encountered with treatment. More effective conventional prosthodontic treatment may have resolved the patient's complaints and eliminated the need for additional implant placement.     

Effects of Implant Design and Surface on Bone Regeneration and Implant Stability: An Experimental Study in the Dog Mandible

Background: Previous experimental studies have shown a higher degree of bone‐implant contact for surface‐enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. Purpose: The purpose of this investigation was to study the integration and stability of grit‐blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit‐blasted, partly microthreaded Astra Tech implants and one standard Branemark implant were bilaterally placed in each dog. On one side, 3 ± 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorpho‐metric evaluation was made after 4 months of healing. Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well‐integrated implants with varying degrees of bone repair at the defect sites. The greater bone‐implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. Conclusions: The Astra Tech implants tested showed a higher degree of bone—implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls.     

Influence of titanium surface charge on fibroblast adhesion

Background: Although dental implants have a high success rate, failure owing to the absence of adhesion between the gingival connective tissue and the implant surface is still being reported. Purpose: This study was designed to evaluate the effect of a titanium surface charge on fibroblast adhesion. Material and Methods: An electrical chamber was custom‐made to generate negative and positive surface charges on commercially pure titanium cylinders with a potential difference of 4.5 V. Twenty‐seven titanium cylinders were divided into three experimental groups. In each group, cell attachment to a positively charged titanium cylinder, a negatively charged titanium cylinder, and a titanium cylinder (control) was studied at three time intervals of 15, 30, and 60 minutes. NCTC clone 929 fibroblasts were used in these experiments. The effect of the potential difference in the pH of Dulbecco's Modified Eagle Medium (DMEM) was also evaluated using two new specimens at time intervals of 15, 30, 60, and 80 minutes. Results: The fibroblast cell attachment was more statistically significant to the positively charged titanium cylinder than the negatively charged titanium cylinder (p =.002) and the control (p=.000), whereas the cell adhesion difference between the control and the negatively charged titanium cylinder was not statistically significant (p=.808). The range of pH difference of the DMEM in the negative and positive parts of the electrical chamber was 0.46 and 0.30, respectively. Conclusion: Within the limitations of this in vitro study, the positive surface charge of the titanium cylinder results in significantly favorable cell adhesion.     

Implant and root supported overdentures - a literature review and some data on bone loss in edentulous jaws

PURPOSE

To present a literature review on implant overdentures after a brief survey of bone loss after extraction of all teeth.

MATERIALS AND METHODS

Papers on alveolar bone loss and implant overdentures have been studied for a narrative review.

RESULTS

Bone loss of the alveolar process after tooth extraction occurs with great individual variation, impossible to predict at the time of extraction. The simplest way to prevent bone loss is to avoid extraction of all teeth. To keep a few teeth and use them or their roots for a tooth or root-supported overdenture substantially reduces bone loss. Jaws with implant-supported prostheses show less bone loss than jaws with conventional dentures. Mandibular 2-implant overdentures provide patients with better outcomes than do conventional dentures, regarding satisfaction, chewing ability and oral-health-related quality of life. There is no strong evidence for the superiority of one overdenture retention-system over the others regarding patient satisfaction, survival, peri-implant bone loss and relevant clinical factors. Mandibular single midline implant overdentures have shown promising results but long-term results are not yet available. For a maxillary overdenture 4 to 6 implants splinted with a bar provide high survival both for implants and overdenture.

CONCLUSION

In edentulous mandibles, 2-implant overdentures provide excellent long-term success and survival, including patient satisfaction and improved oral functions. To further reduce the costs a single midline implant overdenture can be a promising option. In the maxilla, overdentures supported on 4 to 6 implants splinted with a bar have demonstrated good functional results.     

钛表面形貌对人单核细胞活力和粘附影响的实验研究

目的研究钛金属表面形貌对人单核细胞活力和粘附的影响。方法应用机械磨光、酸蚀、喷砂、喷砂酸蚀的表面处理方式形成4种不同的钛片表面形貌,分别设为SiC组、SiC＋F组、63号组和63＋F组。表面粗糙度仪检测钛试件表面粗糙度,以Ra值表征,扫描电镜观测钛试件表面形貌。将离心分离的健康成年人外周血单核细胞接种于处理后钛试件表面,扫描电镜观察培养48 h钛片表面单核细胞粘附情况;四唑盐比色法检测和钛片共同培养1、3、5、7 d的细胞活力。结果 4种钛片表面单核细胞的活力和粘附有差异,置于Ra值最大的63号组培养的单核细胞在第1天、第3天、第5天、第7天都显示了最高的活力,置于Ra值相近的SiC＋F组和63＋F组培养的细胞显示了相似的活力。扫描电镜下观察,表面粗糙的63号组钛片表面粘附了较多的单核细胞,表面多微孔的63＋F组有大量的单核细胞粘附在材料表面的窝洞结构中。结论钛表面形貌影响人单核细胞的活力和粘附。表面粗糙度大促进单核细胞的活力,表面粗糙度大和表面多微孔结构有利于单核细胞的粘附。