影响种植体及其周围组织应力分布的原因分析

人工种植体-骨界面应力分布受多种不同因素影响,包括悬臂梁的存在、种植牙的受力角度、种植体长度、直径和锥度、种植体杨氏模量、种植体基台类型与种植体-骨结合率等。本文就这些因素对种植体-骨界面应力分布的影响,作一综述。     

The relationship of smoking on peri-implant tissue: A retrospective study

The term “peri-implantitis” is used to describe the formation of deep mucosal pockets around dental implants, inflammation of the peri-implant mucosa, and increased resorption of peri-implant bone. It has been speculated that when left untreated, peri-implantitis can result in implant failure. This retrospective study examines a possible correlation between smoking and the appearance of peri-implantitis. The clinical and radiographic observations of 366 implants in 107 patients who smoke were compared with those of a group of 1000 implants in 314 nonsmoking patients. Despite the retrospective nature of this study, a comparison between the two groups was possible. The mean follow-up period, mean patient age, implant locations, and percentages of fixed partial dentures and overdentures were consistent in both groups. There was no significant difference in the mean maxillary and mandibular hygienic indices between the group of smokers and that of nonsmokers. However, the group of smokers showed a higher score in the bleeding index, the mean peri-implant pocket depth, the degree of peri-implant mucosal inflammation, and radiographically discernible bone resorption mesial and distal to the implant. In the maxilla of the smoking group, these observations were significantly higher than both the mandibular observations for smokers and the maxillary observations of the group of nonsmokers (p < 0.01). No differences between the two groups were observed in the mandible. Aside from the systemic effects of tobacco smoking on the human organism, local cofactors seem to be responsible for the higher incidence of peri-implantitis in smokers and have a particularly negative effect on the maxilla. These findings confirm that smokers treated with dental implants have a greater risk of development of peri-implantitis.     

A review on peri-implant crevicular fluid assays potential in monitoring and predicting peri-implant tissue responses

The early and reliable detection of any adverse peri-implant tissue reaction is a prerequisite for treatment planning in patients treated with endosseous dental implants. However, traditional periodontal markers allow only the documentation of the severity of the preexisting destruction. Thus, simple and reliable clinical tests for monitoring peri-implant tissue condition are needed. As the peri-implant crevicular fluid (PICF) is an osmotically mediated inflammatory exudate, changes in flow rate and profile occur according to the condition of the peri-implant tissues. Consequently, peri-implant crevicular fluid analysis may help in detecting early metabolic and biochemical lesions not readily discernible, as well as in monitoring the osseointegration process and the bone response to occlusal loading, thereby improving the long-term success of implants. The purpose of this paper was to review current information on PICF flow rate and profile changes under various clinical conditions and investigate whether specific PICF assays could be useful in the assessment, monitoring and prediction of peri-implant tissue responses.     

种植牙即刻负载与延期负载的生物力学三维有限元分析

目的比较即刻负载和延期负载对种植体骨界面生物力学分布的影响。方法采用CT扫描和自主开发的USIS软件建模,用有限元法计算分析即刻负载和延期负载时种植体骨界面的应力、应变及种植体的位移。结果即刻负载时种植体骨界面的VonMises应力稍小于延期负载,均集中于种植体颈部骨皮质,底部骨松质次之;但VonMises应变有较明显的增加,均集中于种植体底部骨松质和螺纹部位;种植体的位移较延期负载略有增大。即刻负载种植体和延期负载种植体在受到颊舌向力时,VonMises应力、应变及位移均有不同程度的增加。结论即刻负载时种植体骨界面的生物力学分布规律与延期负载时相似,受到侧向力时应力、应变增大。种植牙即刻负载技术是可行的。     

A retrospective study of 1925 consecutively placed immediate implants from 1988 to 2004

PURPOSE: The purpose of the present study was to evaluate implant survival rates with immediate implant placement (IIP) into fresh extraction sockets and to determine risk factors for implant failure. MATERIALS AND METHODS: A retrospective chart review was conducted of all patients in whom IIP was performed between January 1988 and December 31, 2004. Treatment required atraumatic tooth extraction, IIP, and mineralized freeze-dried bone allograft with an absorbable barrier to cover exposed implant threads. Implant failure was documented along with time of failure, age, gender, medical history, medications taken, postsurgical antibiotic usage, site of implant placement, and reason for implant failure. Statistical analysis was performed using chi-square and logistic regression analysis methods. RESULTS: A total of 1925 IIPs (1398 machined-surface and 527 rough-surface implants) occurred in 891 patients. Seventy-one implants failed to achieve integration; a total of 77 implants were lost in 68 patients. The overall implant survival rate was 96.0% with a failure rate of 3.7% prerestoration and 0.3% postrestoration. Machined-surface implants were twice as likely to fail as rough-surface implants (4.6% versus 2.3%). Men were 1.65 times more likely to experience implant failure. Implants placed in sites where teeth were removed for periodontal reasons were 2.3 times more likely to fail than implants placed in other sites. Patients unable to utilize postsurgical amoxicillin were 3.34 times as likely to experience implant failure as patients who received amoxicillin. CONCLUSIONS: With a 1- to 16-year survival rate of 96%, lIP following tooth extraction may be considered to be a predictable procedure. Factors such as the ability to use postsurgical amoxicillin and reason for tooth extraction should be considered when treatment planning for IIP.     

Osteogenic markers in peri-implant crevicular fluid in immediate and delayed-loaded dental implants: A randomized controlled trial

Introduction

The study evaluates the levels of matrix metalloprotease-8 (MMP-8), and Cathepsin-K (CatK) in peri-implant crevicular fluid (PICF) among patients with immediate loaded (IL) and delayed-loaded (DL) implants at different time points to know the inflammation and osteogenic status.

Methods

The study population consisted of two groups (n = 25, each group) with a mean age of 28.7 ± 3.5 years, and PICF was collected. MMP-8 and CatK levels were quantified through ELISA.

Results

We observed the concentrations of inflammatory markers (MMP-8 and CatK) at three time points in the IL and DL groups. The mean concentration of MMP-8 in the IL group was 9468 ± 1230 pg/mL, 5547 ± 1088 pg/mL, and 7248 ± 1396 pg/mL at 2 weeks, 3 months, and 12 months, respectively; while in the DL group was 10 816 ± 779.7 pg/mL, 9531 ± 1245 pg/mL, and 9132 ± 1265 pg/mL at 2 weeks, 3 and 12 months, respectively. The mean concentration of Cat-K in the IL group was observed at 422.1 ± 36.46 pg/mL, 242.9 ± 25.87 pg/mL, and 469 ± 75.38 pg/mL at 2 weeks, 3, and 12 months, whereas in the DL group was 654.6 ± 152.9 pg/mL, 314.7 ± 28.29 pg/mL, and 539.8 ± 115.1 pg/mL at 2 weeks, 3 months and 12 months, respectively.

Conclusion

In this study, the levels of CatK and MMP-8 levels decline at 12 months in both groups, and the IL group shows lower values compared to the DL group; however, no significant changes were observed after analyses were adjusted for multiple comparisons (p > 0.025). Therefore, there is not much difference observed in the inflammation process between immediate and delayed loading. (Clinical trial identifier: CTRI/2017/09/009668).     

Long-term follow-up of dental single implants under immediate orthodontic load

Objective:To evaluate the success of osseointegrated implants under immediate prosthetic and orthodontic forces after a follow-up period of at least 2 years.Materials and Methods:The sample included 20 titanium implants which were used as orthodontic and prosthetic anchorage of immediately loaded single-crowns on a total of 13 patients. A 40 N initial torque was considered the minimum for inclusion in the sample. All implants received screwed provisional crowns immediately after surgery. The implants were randomly divided into two groups: the control group (9 implants) and the immediate orthodontic loading group (11 implants). A healing period of 4 months was observed before orthodontic loads were applied to the control group implants. For the immediate orthodontic loading group, orthodontic forces were applied within 24 hours. The maximum orthodontic force applied in both groups was 200 g. After 6 months of orthodontic movement, clinical and radiographic evaluations were obtained. Implants were considered successful when favorable results were obtained in all evaluations.Results:After a 2-year follow-up, the success rates were 90.9% and 88.9%, respectively, in the orthodontic loading group and the control group. Each group had one failure.Conclusion:Shortening the healing period for the application of orthodontic forces did not seem to affect the success of osseointegrated implants used as anchorage.     

A prospective clinical study of bone augmentation techniques at immediate implants

The efficacy of combinations of membranes and autogenous bone grafts at immediate implants were compared in a prospective study. Sixty-two consecutively treated patients each received an immediate implant for a single tooth replacement at a maxillary anterior or premolar site. Dimensions of the peri-implant defect at the implant collar were measured as follows: vertical defect height (VDH), horizontal defect depth (HDD) and horizontal defect width (HDW). Each implant randomly received one of five augmentation treatments and were submerged with connective tissue grafts: Group 1 (n=12)--expanded polytetrafluoroethylene membrane only, Group 2 (n=11)--resorbable polylactide/polyglycolide copolymer membrane only, Group 3 (n=13)--resorbable membrane and autogenous bone graft; Group 4 (n=14)--autogenous bone graft only, and Group 5 (n=12)--no membrane and no bone graft control. At re-entry, all groups showed significant reduction in VDH, HDD and HDW. Comparisons between groups showed no significant differences for VDH (mean 75.4%) and HDD (mean 77%) reduction. Significant differences were observed between groups for HDW reduction (range, 34.1-67.3%), with membrane-treated Groups 1, 2 and 3 showing the greatest reduction. In the presence of dehiscence defects of the labial plate, HDW reduction of 66.6% was achieved with membrane use compared with 37.7% without membranes. Over 50% more labial plate resorption occurred in the presence of a dehiscence defect irrespective of the augmentation treatment used. The results indicate that VDH and HDD reduction at defects adjacent to immediate implants may be achieved without the use of membranes and/or bone grafts.     

Monocrystalline aluminum dental implants in animals: a study of the peri-implant tissue

After the extraction of two molars in a dog's jaw, a single crystal alumina screw was implanted. Monthly radiographs were taken and analyzed by means of a video display computer (VDC) to obtain densitometric informations about the interface. After one year implantation, the bone segment containing the prosthesis was fixed in 4% paraformaldehyde, embedded in methacrylate and sectioned by a microtome saw. The results in light microscopy with ordinary and polarized light, in SEM and X-ray microanalysis, show the presence of a thick connective tissue layer interposed between the screw and the bone. The histological findings confirm the results obtained through the VDC analysis of the radiographic images.     

无牙颌种植后即刻负重的临床回顾研究

目的探讨无牙颌患者种植后进行即刻负重修复技术的可行性和临床效果。方法从2012年1月至2015年3月间,共22例无牙颌患者合计140枚种植体植入后行即刻负重,均于48 h内完成种植体支持的临时义齿修复,4~6个月后行永久修复。对该修复方案下的种植体留存率、种植体边缘骨吸收情况、种植体稳固性及周围龈组织状况以及患者应用的临床效果进行观察和研究。结果 22例共140枚种植体行即刻负重,其中有3枚种植体失败,种植体留存率为97.9%。种植体负重后6个月和12个月的边缘骨吸收量分别为(0.62±0.11)mm和(0.74±0.13)mm。通过对患者的病例回顾发现共有4例发生不同程度的机械并发症,包括修复体折裂、重衬、人工牙脱落等。种植体周围龈组织健康,未出现明显的红肿。临时义齿固位良好,患者满意度高。结论选择适当的病例,应用种植外科和修复技术对无牙颌患者行即刻负重修复是可行的,可获得理想的临床效果,近期疗效可靠。     

Influence of immediate implant loading on peri-implant soft tissue morphology in the edentulous maxilla

PURPOSE: This study investigates the pre- and posttreatment morphology of the mucosa around immediately loaded implants in the edentulous maxilla. MATERIALS AND METHODS: Implants were placed and immediately loaded in edentulous maxillae; pre- and posttreatment impressions were obtained. The resulting casts were digitalized into 3-dimensional images, and the pre- and posttreatment images were superimposed. The width and height of the maxillary alveolar process were measured at central and interproximal implant sites in a vertical section of the superimposed holograms. For statistical analysis, the Delta value (d) was defined as the difference between the pre- and posttreatment images for all measurements. RESULTS: Sixty-seven Straumann implants placed in 9 patients and immediately restored with provisional fixed restorations were analyzed. An increase in width at all measurement sites was observed after treatment. Width increased for both central implant (1.51 +/- 1.16 mm, P < .001) and interproximal implant sections (1.02 +/- 1.21 mm, P < .001). Mean d for height was found to be decreased at central implant sites (-1.21 +/- 1.67 mm, P = .012) and at interproximal sections (-0.72 +/- 1.68 mm, P = .098). DISCUSSION AND CONCLUSION: Clinically, it has been observed that the placement of an immediate provisional affects the peri-implant tissue morphology according to its emergence profile. The result after treatment was a wider contour of the peri-implant soft tissue, located in a more apical position than the original mucosal level. The most coronal part of the papilla-like mucosa at interproximal sites would be nearest to the original mucosal level before treatment. The scalloped mucosal configuration obtained was consistent along the rehabilitated arch. Statistically significant dimensional changes of the peri-implant mucosa were observed with an immediate loading approach.     

A single-center retrospective analysis of 1001 consecutively placed NobelActive implants

This single-center retrospective study evaluated the survival rates of the NobelActive implant (Nobel Biocare AB, Gothenburg, Sweden) with a tapered body design. One thousand and one implants demonstrated a cumulative survival rate of 97.4% (97.1% in maxilla and 98% in the mandible) for up to 31 months of loading.