Transmission of Periodontopathic Bacteria from Natural Teeth to Implants

Purpose: Prevention of peri‐implantitis is essential for the success of implant rehabilitation. Infection by periodontopathic bacteria is a major cause of peri‐implantitis. The aim of the present study was to identify the source of peri‐implant colonization by periodontopathic bacteria. Materials and Methods: Twenty‐one patients with implants were enrolled in the study. Subgingival plaque samples from the adjacent, occluding, and contralateral natural teeth were collected prior to second‐stage surgery. Samples from implant sulci were then obtained 2 weeks later. Detection of periodontopathic bacteria was performed by the polymerase chain reaction. Results: The detection rates for Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum in all subgingival samples from natural teeth were similar to that in the peri‐implant sulci. Multiple logistic regression analysis revealed an association between the detection of A. actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, and F. nucleatum in the gingival crevices of adjacent teeth and that of the peri‐implant sulcus, but no association for Tannerella forsythia. Conclusions: The present findings suggest that colonization by A. actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, and F. nucleatum at the implant sulcus was affected by these microorganisms in the gingival crevice of adjacent teeth rather than those on occluding and contralateral teeth.     

Tactile Sensibility of Single‐Tooth Implants and Natural Teeth Under Local Anesthesia of the Natural Antagonistic Teeth

Introduction and Aim: The term osseoperception describes the capability of developing a subtle tactile sensibility over dental implants. The present clinical study aims at clarifying the question of how far tactile sensibility is to be attributed to the periodontium of the natural opposing tooth of the implant. Material and Method: Thirty‐two subjects with single‐tooth implants with natural opposing teeth were included in this clinical, single‐blind, split‐mouth study. The natural antagonistic tooth of the implant and the corresponding natural contralateral tooth were anesthetized with a locally infiltrated articaine anesthetic. In a computer‐assisted and randomized way, copper foils of varying thickness (0–100 µm) were placed interocclusally between the single‐tooth implant and the natural opposing tooth, and between the contralateral pair of natural opposing teeth in order to investigate the active tactile sensibility according to the psychophysical method of constant stimuli and evaluate it statistically by the Weibull distribution. Results: The average tactile sensibility of the implants with anesthetized antagonists at the 50% value calculated by means of the Weibull distribution was 20 ± 11 µm with a support area (90%–10% value) of 77 ± 89 µm. For the pair of natural teeth, the tactile sensibility at the 50% value was 16 ± 9 µm with a support area of 48.4 ± 93 µm. This resulted in an average intraindividual difference of 3.5 ± 7 µm at the 50% value and 29 ± 93 µm in the support area. The statistical calculations demonstrated an equivalent tactile sensibility (50% value) of the single‐tooth implant and the contralateral natural control tooth with the natural antagonists being anesthetized in each case (double t‐test, equivalence limit ± 8 µm, P < 0.01, power >80%). Conclusion: Apparently, the active tactile sensibility of single‐tooth implants with natural opposing teeth is not only to be attributed to the periodontium of the opposing tooth but also to a perception over the implant itself. This could support the hypothesis according to which the implant may have a tactile sensibility of its own.     

Biomarkers and Bacteria Around Implants and Natural Teeth in the Same Individuals

Background: This cross‐sectional study assesses cytokine levels in peri‐implant crevicular fluid (PICF)/gingival crevicular fluid (GCF) and a selection of subgingival/submucosal plaque bacteria from clinically healthy or diseased sites in the same individuals. Methods: Samples from 97 implants/teeth (58 implants [19 healthy, 20 mucositis, 19 peri‐implantitis] and 39 natural teeth [19 healthy, 12 gingivitis, eight periodontitis] in 15 systemically healthy patients were investigated by immunoassay and real‐time polymerase chain reaction. Samples were obtained first, with probing depth, clinical attachment level, bleeding on probing, plaque index scores, and keratinized tissue width then recorded. Data were analyzed by Wilcoxon, Mann–Whitney U, and permutation tests on dependent, independent, and mixed dependent and independent samples and Spearman correlation. Results: Interleukin (IL)‐1β levels were significantly higher in PICF samples of healthy implants than in GCF samples of healthy teeth (P = 0.003), and soluble receptor activator of nuclear factor‐κB ligand (sRANKL) concentrations were significantly higher in the gingivitis than the mucositis group (P = 0.004). Biomarker levels were similar in peri‐implantitis and periodontitis groups (P >0.05). Actinomyces naeslundi and Streptococcus oralis levels were significantly higher in the healthy implant group than in healthy teeth (P <0.05). Prevotella intermedia and Treponema denticola (Td) levels were lower in the mucositis group than the gingivitis group (P <0.05). Prevotella oralis and S. oralis levels were significantly higher in the periodontitis group (P <0.05), and Td levels were significantly higher in the peri‐implantitis group (P <0.05). Conclusion: There were many similarities but, crucially, some differences in biomarker levels (IL‐1β and sRANKL) and bacterial species between peri‐implant and periodontal sites in the same individuals, suggesting similar pathogenic mechanisms.     

A Three‐Dimensional Finite Element Analysis for Overdenture Attachments Supported by Teeth and/or Mini Dental Implants

Purpose: The aim of this study was to establish the optimum design and attachment combination to support an overdenture with minimal stress and flexing produced in the alveolar bone surrounding any natural teeth and/or mini dental implants. Materials and Methods: Twelve models were included in the study: the six main models (A, B, C, D, E, and F) were categorized according to the support designs of the overdenture prosthesis, and each model was further subdivided according to the attachment combinations into model 1: with Dalbo elliptic and/or O‐ring attachments only and model 2: with flexible acrylic attachments. Vertical loads (35 N) and 17.5 N lateral loads under static conditions were applied to the models to simulate the occlusal forces following the concept of lingualized occlusion. All conditions were created using a finite element software program. Maximum von Mises stress at the level of the attachments and at the bone support foundation interfaces were compared in all 12 models. The flexing of the mandible and the attachments were also compared qualitatively. Results: Stress on these models was analyzed after the given loading condition. The results showed that the model with three freestanding mini dental implants and flexible acrylic attachments showed the lowest von Mises stress and flexing, while the models with four freestanding mini dental implants and O‐ring attachments showed the highest von Mises stress. Conclusion: Three freestanding mini dental implants with flexible acrylic attachment systems supporting an overdenture were better choices than four mini dental implants with O‐ring attachment systems, which showed the maximum flexing and stress values in this qualitative comparison.     

A Cross‐Sectional Assessment of Biomarker Levels Around Implants Versus Natural Teeth in Periodontal Maintenance Patients

Background: Recent studies point to the clinical utility of using peri‐implant sulcular fluid (PISF) as a valuable diagnostic aid for monitoring peri‐implant tissue health. The objectives of this study are to determine the levels of key biomarkers in PISF in periodontal maintenance participants and compare them with their corresponding levels in gingival crevicular fluid (GCF) obtained from the same participants. Methods: PISF and GCF were collected from an implant and a contralateral natural tooth after the clinical examination of 73 participants. The levels of interleukin (IL)‐1α, IL‐1β, IL‐6, IL‐8, IL‐10, IL‐12, IL‐17A, tumor necrosis factor (TNF)‐α, C‐reactive protein, osteoprotegerin, leptin, and adiponectin were determined using multiplex proteomic immunoassays. The correlation of biomarker concentrations between GCF versus PISF, within GCF or PISF, and with several covariates (age, brushing frequency, days since professional cleaning, probing depth [PD], and plaque index) were also determined. Results: Significantly higher levels of IL‐17A (P = 0.02) and TNF‐α (P = 0.03) were noted in PISF when compared with their levels in GCF. Significant positive correlations were noted between the concentrations of cytokines in PISF versus their levels in GCF. Among the covariates, a significant positive correlation was noted between mean PDs around implants and levels of IL‐1β (P <0.05) and IL‐8 (P <0.05) in PISF. Conclusion: The results of this study point to the differential expression of specific biomarkers in GCF versus their levels in PISF in periodontal maintenance patients, which is critical information before establishing PISF as a diagnostic fluid to monitor peri‐implant health.     

种植体-杆卡式附着体在牙槽骨骨量严重不足修复中的应用

目的:评价种植体-杆卡式附着体在牙槽骨骨量严重不足修复中的应用效果.方法:2008-2010年20例牙槽骨骨量严重不足患者行种植牙手术,并用种植体-杆卡式附着体进行修复.使用测力仪和T-scan2咬合力测定仪检查义齿的固位力和咬合力.结果:用种植体-杆卡式附着体修复,能获得＞15 N的固位力,咬合力接近天然牙.结论:种...     

压低犬牙致牙周膜微循环即期变化的实验研究

目的：研究牙齿在压低移动过程中牙周膜（PDL）微循环的变化。方法：任选一侧上第四前磨牙作支抗牙,利用带圈压低曲压低第二前磨牙,对侧同名牙作对照。采用墨汁灌注技术,利用图像分析仪对组织切片进行分析和观察。结果：100g力压低狗上颌第二前磨牙2h后,牙周膜微循环发生了明显改变,表现为微血管管径及体密度明显减少,而微血管总数未见明显减少,亦未引起牙周膜微循环的障碍。结论：100克压低力引起的即期反应为PDL微循环的适应性改变,避免牙周膜受到过大负荷,减轻组织损伤,这说明牙周膜微循环对保障牙周组织的健康和发挥正常功能起着非常重要的作用。     

Molar Intrusion with Implants Using a Bite Plane Appliance: A Case Report

Background: Orthodontic forces for tooth intrusion ought to be continuous and low, which may be achieved with the help of osseointegrated implants. Purpose: The aims of this study were to describe a method to intrude supererupted maxillary molars using interarch intrusion mechanics (a bite plane appliance) with implants and to assess anchor implant stability through resonance frequency analysis (RFA; Osstell?, Mentor version 2, Integration Diagnostics AB, Göteborg, Sweden) in comparison with nonanchorage control implants during orthodontic intrusion. Materials and Methods: A 48‐year‐old female patient was treated with implants (36 and 37 regions, Brånemark Implant System®, MkIII TiUNite?, Nobel Biocare AB, Göteborg, Sweden; lengths, 13 and 10 mm; diameter, 5 mm) serving as orthodontic anchorage for intrusion of supraerupted teeth in the maxilla (teeth 26 and 27) using a bite plane appliance. The force of intrusion applied was individual discontinuous bite force in the present case. The control implants were in the sites 45, 46, and 47 with healing abutments out of loading. Stability of both the anchorage and control implants was assessed by RFA from the commencement of orthodontic intrusion (7 months after the first‐stage surgery) to the end of the study (19 months after the first‐stage surgery). Marginal bone height measurements of both implants were performed on radiographs at the same time. Results: The treatment was completed without complications or abnormalities of the intruded teeth or the opposite anchorage implants. However, implant stability quotient values of the anchored implants obviously changed during the initial 4 months after commencement of intrusion compared with control implants. In the present case, an intrusion of 2.2 mm was achieved in 12 months. Conclusions: The present method made it possible to intrude molars successfully. However, further studies with more cases are needed to clarify the reliability of the method and determine how to control the bite forces applied as orthodontic load.     

Patient Evaluation of Treatment with Fixed Prostheses Supported by Implants or a Combination of Teeth and Implants

PURPOSE: The objective of this study was to compare treatment outcomes among subjects with complete arch fixed prostheses in the maxilla, supported by implants or a combination of natural teeth and dental implants. MATERIALS AND METHODS: Twenty-one subjects with maxillary tooth- and implant-supported fixed prostheses and 21 subjects with maxillary implant-supported fixed prostheses were identified and included in the study. All abutment teeth in the group with tooth- and implant-supported prostheses were provided with cemented copings that incorporated threads for vertical locking screws. Frameworks were fabricated with a gold alloy that was veneered with acrylic resin or ceramic materials. All frameworks were screw-retained to implants and copings. Frameworks in the group with implant-supported prostheses were fabricated with milled titanium or gold alloy to which denture teeth and resin base material were applied. All prostheses had a minimum of 8 units, at least 4 of which were in one quadrant. Subjects in both groups were mailed a questionnaire consisting of 15 questions focused on various factors related to treatment outcome, such as oral function and patient satisfaction. RESULTS: The response rate was 86%. Both groups reported a high satisfaction rate for most items with few regretting their choice of treatment. Most individuals in both groups reported great improvement in chewing ability and few reported phonetic disturbances. No statistically significant differences were found between the groups. CONCLUSION: The results of the present study showed similarity in questionnaire responses between the 2 groups of participants. High satisfaction was reported both among subjects who received a complete arch fixed prosthesis in the maxilla supported by dental implants only, as well as among those whose prostheses were supported by a combination of natural teeth and dental implants.     

Mechanical Properties of Magnetic Attachments for Removable Prostheses on Teeth and Implants

Purpose: Magnetic attachments on teeth and implants may be used to improve stability, support, and retention of removable prostheses. Various forms of magnetic attachments are available, divided according to the design, the mechanical properties of the attachments, and the clinical indication. Recently developed attachment systems are small and promise improved retentive capacity, while existing magnetic attachments continue to be technologically modified and improved. This investigation reviewed and compared maximum retentive forces and characteristic curves for magnetic attachments indicated for use as root anchors and on implants. Materials and Methods: Twenty‐four samarium‐cobalt (SmCo) and neodym‐iron‐boron (NeFeB) magnetic attachments (12 tooth‐ and 12 implant‐borne) were evaluated. Specimens were delivered by the manufacturers or fabricated according to their instructions. Five magnet pairs of each product and each combination were tested 10 times in a calibrated universal testing machine using a nonmagnetic test device (s = 40 mm, v = 20 mm/min). Results were recorded electronically and compared to manufacturers' details. Results: Maximum retentive forces for root keepers ranged from 1.4 to 6.6 N. Maximum retentive forces for magnetic attachments on implants ranged from 0.7 to 5.8 N. After a distance of 0.1 mm, a complete reversed distribution of the different systems became obvious. The retentive force provided by the manufacturer was achieved in one implant abutment, with retentive force (as compared to those provided by the manufacturers) for root keepers ranging between 42.5% and 92.9% and for implant abutments between 43.0% and 99.4%. Conclusion: There were differences between magnetic attachments for both the initial retentive capabilities and the characteristic curves. Recently introduced products provided relatively high initial retentive forces despite their small size. The measured retentive forces and the manufacturer's information differed in the majority of magnetic systems evaluated.     

种植体与杆卡式附着体用于义耳修复

将３只骨融合式螺旋种植体植入耳缺损区，采用杆卡式附着体作为种植上的部结构和义耳的固体装置，解决义耳固位，这种固位方式具有固位可靠，取戴方便，便于自洁，利于局部组织健康等优点，特别是在对抗侧向力方面具明显的优越性，是目前义耳修复最佳的固位方式。     

Investigations On A Cell Culture Medium For Storage And Transportation Of Avulsed Teeth

Non-physiologic storage of avulsed teeth leads to a high incidence of root resorption, resulting in poor prognosis. This study investigated the suitability of specially composed cell culture media for storage of extracted teeth for up to 48 hours. Autoradiographic investigations revealed that the proliferative activity of periodontal ligament (PDL) cells of teeth stored in cell culture medium for up to 48 hours increased with storage time. Studies on proliferation of PDL cells after storage of teeth in different media for up to 24 hours demonstrated that the proliferative activity is dependent on the composition of the medium. Immunohistochemical investigations with markers for cell proliferation revealed that pulp cells of extracted immature teeth show numerous proliferations after storage for up to 24 hours in a special cell culture medium but few proliferations after storage in Hanks Balanced Salt Solution (HBSS). The investigations indicate that a special cell culture medium can preserve cell viability of PDL cells adhering to extracted teeth for at least 48 hours. The in vitro results are confirmed by a case presented: After storage of two upper central incisors for 36 hours in the cell culture medium the teeth could be successfully reimplanted after extraoral insertion of titanium posts into the root canal (auto-alloplastic reimplantation). Clinical and radiological follow-up examinations for 12 months revealed normal periodontal healing.