Early colonization of dental implants by putative periodontal pathogens in partially edentulous patients

There is limited scientific information available on the early colonization of the peri-implant pockets in partially edentulous individuals. Knowledge about this process is one step in better understanding the etiology and pathogenesis of peri-implantitis. In this study, the early colonization of the peri-implant pockets by putative periodontal pathogens was studied in 20 partially edentulous individuals using anaerobic culture techniques. At baseline, the presence and levels of putative periodontal pathogens in the microflora of periodontal pockets and saliva were established. Immediately after loading of the titanium implants and after 6 and 12 months the presence and levels of selected putative periodontal pathogens were determined in periodontal and peri-implant pockets. A second aim was to detect bacterial contamination of the implant site and the inside of the implant. At baseline, the most frequently isolated species from the periodontal pockets were Fusobacterium nucleatum, Prevotella intermedia and Peptostreptococcus micros. Bacteroides forsythus, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were isolated from 9, 2 and 3 patients respectively. Six months after placing of the bridges, the majority of the implant sites had detectable levels of most periodontal bacterial species with the exception of A. actinomycetemcomitans which could not be isolated from any of the peri-implant samples during the experimental period, although 2 patients had this organism at baseline. In 2 patients with detectable subgingival P. gingivalis at baseline this species was found after 12 months in the peri-implant sites. One of these patients lost 2 implants which was associated with a high proportion of P. gingivalis in the peri-implant pockets. A second patient developed 2 fistulas around 2 implants at 8 months and this event was also associated with the presence of P. gingivalis. It is concluded that proper periodontal infection control before installment of dental implants in partially edentulous patients may prevent early bacterial complications.     

One-year bacterial colonization patterns of Staphylococcus aureus and other bacteria at implants and adjacent teeth

AIMS: (i) To assess the pattern of early bacterial colonization on titanium oral implants after installation, at 12 weeks and at 12 months, (ii) to compare the microbiota at submucosal implant sites and adjacent subgingival tooth sites and (iii) to assess whether or not early colonization was predictive of 12-month colonization patterns. MATERIAL AND METHODS: Submucosal/subgingival plaque samples from 17 titanium oral implants and adjacent teeth were analyzed by checkerboard DNA-DNA hybridization 30 min, 12 weeks and 12 months after implant installation. RESULTS: At 12 months, none of the inserted implants had been lost or presented with signs of peri-implantitis. The distribution of sites at implants and teeth with bleeding on probing varied between 2% and 11%. Probing pocket depths < or =3 mm were found at 75% of implant sites. At 12 months, the sum of the bacterial counts of 40 species was statistically significantly higher at tooth compared with implant sites (mean difference: 34.4 x 10(5), 95% confidence interval -0.4 to 69.4, P<0.05). At 12 months, higher individual bacterial counts at tooth sites were found for 7/40 species compared with implant sites. Detection or lack of detection of Staphylococcus aureus at implant sites at 12 weeks resulted in the highest positive (e.g. 80%) and negative (e.g. 90%) predictive values, respectively. Between 12 weeks and 12 months, the prevalence of Tannerella forsythia increased statistically significantly at implant sites (P<0.05). Lack of detection of Porphyromonas gingivalis at 12 weeks yielded a negative predictive value of 93.1% of this microorganism being undetectable at implant sites at 12 months. CONCLUSIONS: Within the limits of this study, the findings showed (i) a few differences in the prevalence of bacterial species between implant and adjacent tooth sites at 12 months and (ii) high positive and negative predictive values for selected bacterial species.     

Macrophage colonization of infected and noninfected dental tissues in vitro

Abstract — Attachment and spreading of phagocytes on a mineralized tissue surface is crucial for their proper resorptive function. In other studies, attachment and spreading have been shown to be highly dependent on the nature and composition of the surface. In the present study, peritoneal macrophages were cultured on infected and non-infected mineralized and non-mineralized dental tissues, which were examined with scanning electron microscopy at different observation periods. Although some cells had attached to non-infected predentin, only a few showed signs of spreading, even after long incubation times. This contrasted with the behavior of macrophages cultivated on enamel, mineralized dentin and infected predentin. Most of these cells showed spreading and the characteristics of active, phagocytosing cells. The reluctance of macrophages to spread on non-infected predentin was suggested to be due to the non-mineralized nature of this tissue, although an influence of endogenous resorption inhibitors cannot be excluded.     

Trauma to an osseointegrated anterior dental implant: a case report

Abstract –  Single tooth implant systems have been shown to offer a safe and highly predictable option for the replacement of anterior teeth. There is however, a paucity of evidence on the result of trauma to single tooth implant systems, particularly in the vulnerable anterior maxillary area. This article presents a report on the outcome of a traumatic incident to an osseointegrated single tooth implant.     

Early colonization of non-submerged dental implants in patients with a history of advanced aggressive periodontitis

The aim of the study was to evaluate the early colonization of non-submerged implants over a 6-month period in partially edentulous patients treated for advanced aggressive periodontal disease. In 22 patients treated for advanced aggressive periodontitis and in a supportive maintenance program for a period between 12 and 240 months at implant surgery, a total of 68 non-submerged dental implants were installed. Patients had a plaque score below 20%, and less than 20% of the pockets around the teeth were bleeding on probing (BOP). Using DNA-probes (micro-IDent), the presence and concentration of five periodontal pathogens (Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythensis (Tf) and Treponema denticola (Td)) were determined in the five deepest pockets of the rest dentition pre-operatively and after 6 months as well as five places around each implant 10 days, 1 month, 3 months and 6 months after surgery. In each patient, a test to determine the genotype interleukin-1 (IL-1) was performed (PST - micro-IDent). After 6 months, no difference in microbial composition as compared with baseline was found around the teeth in five patients, in 12 minute differences and in five patients important differences were observed. Ten days after surgery, three patients had a complete similar bacterial composition between teeth and implants. In 14 patients, the composition was fairly similar, while large differences in composition and concentration occurred in five patients. This microbiota around the implants remained almost unchanged over a 6-month period and did not hamper the clinical and radiographic osseointegration and did not lead to peri-implantitis, mucositis or initiation of bone destruction.     

Influences of internal tapered abutment designs on bone stresses around a dental implant: three-dimensional finite element method with statistical evaluation

Background: The aim of this study is to determine the effects of various designs of internal tapered abutment joints on the stress induced in peri‐implant crestal bone by using the three‐dimensional finite element method and statistical analyses. Methods: Thirty‐six models with various internal tapered abutment–implant interface designs including different abutment diameters (3.0, 3.5, and 4.0 mm), connection depths (4, 6, and 8 mm), and tapers (2°, 4°, 6°, and 8°) were constructed. A force of 170 N was applied to the top surface of the abutment either vertically or 45° obliquely. The maximum von Mises bone‐stress values in the crestal bone surrounding the implant were statistically analyzed using analysis of variance. In addition, patterns of bone stress around the implant were examined. Results: The results demonstrate that a smaller abutment diameter and a longer abutment connection significantly reduced the bone stresses (P <0.0001) in vertical and oblique loading conditions. Moreover, when the tapered abutment–implant interfaced connection was more parallel, bone stresses under vertical loading were less (P = 0.0002), whereas the abutment taper did not show significant effects on bone stresses under oblique loading (P = 0.83). Bone stresses were mainly influenced by the abutment diameter, followed by the abutment connection depth and the abutment taper. Conclusion: For an internal tapered abutment design, it was suggested that a narrower and deeper abutment–implant interface produced the biomechanical advantage of reducing the stress concentration in the crestal region around an implant.     

Plasmacytoma of the mandible associated with a dental implant failure: a clinical report

The case report of a patient is presented who had been suffering from a plasmacytoma of the spine several years back, and who had developed a new plasmacytoma of the mandible, 3 years subsequent to the insertion of a dental implant. This second solitary lesion occurred 15 years after the first one, and without signs of conversion to multiple myeloma. Research in animal models has shown multinucleated giant cells, belonging to the monocyte-macrophage lineage, persisting between the titanium surface and the lymphohemopoietic compartment, at least 1.5 years after implant insertion. Factors that increase the proliferative activity of precursor B cells, for example a protracted macrophage activation, are likely to increase the risk of B cell oncogenesis. A possible role of the titanium surface in an increase of precursor B cell proliferative activity, thus facilitating a new localization, was evaluated.     

Bone collected during dental implant surgery: a clinical and histological study

Bone traps vary in design, although the effect of pore size on the nature of the debris collected in vivo has not yet been established. The aims of this study were 1) to compare the clinical performance of two bone collectors during implant surgery, ii) to establish the mass of tissue collected by each device, and iii) to characterize the nature of the collected debris. Thirty-eight patients (paired for implant site) were categorised into three clinical groups according to the site and the number of implants they were to receive. Patients underwent bone collection with the Frios bone trap or the Osseous Coagulum Trap according to a randomisation sequence. The samples were fixed in formalin, frozen, freeze-dried and weighed. Material from each sample was embedded in paraffin wax and stained with haematoxylin and eosin. All sections were examined by optical microscopy and the proportion of bone to coagulum was established histomorphometrically. During surgery, the Frios bone trap blocked once and the Osseous Coagulum Trap blocked 11 times. In all cases where blockage occurred, excess coagulum was apparent. All the samples that were collected by the Frios bone trap contained bone and coagulum, with a mean proportion of 90.6% bone. With regard to the Osseous Coagulum Trap, one sample contained no bone and two samples contained only trace amounts of bone; the remaining samples contained a mean proportion of 67.3% bone. Pore size affects both clinical performance and the histological composition of the debris collected, and this might have important implications if used as an augmentation material.     

Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle

Aim: The aim of this prospective comparative pilot study was to evaluate hard and soft peri‐implant tissues in patients with a missing adjacent central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns up to 1 year after functional loading. Material and methods: In the “Implant–cantilever group”, five patients were treated with one dental implant in the region of the central incisor (NobelReplace Groovy Regular Platform). In the “Implant–implant group”, five patients were treated with two adjacent dental implants: at the position of the central incisor (NobelReplace Groovy Regular Platform) and at the position of the lateral incisor (NobelReplace Groovy Narrow Platform). Implant survival, pocket probing depth, papilla index, marginal bone level and patient satisfaction were assessed during a 1‐year follow‐up period. Results: No implants were lost during the 1‐year follow‐up. Mean pocket probing values of the implants were comparable between the two groups. Papilla index scores in both groups were relatively low, pointing towards a compromised papilla. Marginal bone loss was minimal and comparable between the groups. Patient satisfaction was very high in both groups. Conclusion: In this 1‐year prospective comparative study, no large differences in hard‐ and soft‐tissue levels could be shown between patients with a missing central and lateral upper incisor treated with either one implant and an implant crown with a cantilever or two implants with solitary implant crowns. To cite this article:
Tymstra N, Raghoebar GM, Vissink A, Meijer HJA. Dental implant treatment for two adjacent missing teeth in the maxillary aesthetic zone: a comparative pilot study and test of principle.
Clin. Oral Impl. Res. 22 , 2011; 207–213.
doi: 10.1111/j.1600‐0501.2010.02017.x     

原位菌斑生物膜的一种完整获得方法和结构研究

目的:通过对一种方法获得原位牙菌斑生物膜的结构分析,证明这种方法的可行性。方法:选择安装有局部可摘义齿的志愿者在基托表面粘贴塑料片的方法,在塑料片上可获得1、4、24h牙菌斑生物膜,并用激光共聚焦扫描显微镜进行结构的观察和分析。结果:牙菌斑生物膜的细菌、基质清楚可见,1、4、24h菌斑生物膜的平均厚度分别是(21.41±0.03)μm,(34.03±0.02)μm,(58.53±0.03)μm。结论:这种方法获取的菌斑生物膜结构完整、简便可行,是一种很好的获取原位牙菌斑生物膜的方法,可为进一步的实验提供平台。     

The primary stability of two dental implant systems in low-density bone

Primary stability in low-density bone is crucial for the long-term success of implants. Tapered implants have shown particularly favourable properties under such conditions. The aim of this study was to compare the primary stability of tapered titanium and novel cylindrical zirconia dental implant systems in low-density bone. Fifty implants (25 tapered, 25 cylindrical) were placed in the anterior maxillary bone of cadavers meeting the criteria of low-density bone. The maximum insertion (ITV) and removal (RTV) torque values were recorded, and the implant stability quotients (ISQ) determined. To establish the isolated influence of cancellous bone on primary stability, the implantation procedure was performed in standardized low-density polyurethane foam bone blocks (cancellous bone model) using the same procedure. The primary stability parameters of both implant types showed significant positive correlations with bone density (Hounsfield units) and cortical thickness. In the cadaver, the cylindrical zirconia implants showed a significantly higher mean ISQ when compared to the tapered titanium implants (50.58 vs 37.26; P < 0.001). Pearson analysis showed significant positive correlations between ITV and ISQ (P = 0.016) and between RTV and ISQ (P = 0.035) for the cylindrical zirconia implants; no such correlations were observed for the tapered titanium implants. Within the limitations of this study, the results indicate that cylindrical zirconia implants represent a comparable viable treatment option to tapered titanium implants in terms of primary implant stability in low-density human bone.     

种植体周围软组织厚度干预的临床研究

目的：对种植体周软组织厚度通过手术方式进行干预,观察该干预对种植体周健康状况的影响。方法：在种植义齿Ⅱ期手术过程中,对于软组织厚度〉5mm者行斜形切口;对于软组织厚度预期〈1.5mm者行结缔组织移植术。两者均调整软组织厚度至2.5～3mm,以对侧同名部位的种植牙为对照组,于种植体修复后半年,检测种植体周牙龈炎症指数（GI）、龈沟内金属基质蛋白酶-8（MMP-8）含量,以及种植体周骨丧失（BL）。结果：与对照组相比,斜形切口组MMP-8含量、BL均显著降低（P〈0.05）,结缔组织移植组GI、MMP-8、BL均无显著性变化。结论：适当的种植体周围软组织厚度处理有利于维护种植体周软组织的健康。     

Levels of glycosaminoglycans in peri‐implant sulcus fluid as a means of monitoring bone response to endosseous dental implants

The presence of certain glycosaminoglycans in peri‐implant sulcus fluid may be an effective means of monitoring changes in bone metabolic activity following initial loading of implant abutments. This study has investigated levels of chondroitin 4 sulphate and hyaluronan in peri‐implant sulcus fluid from titanium osseointegrated implants following initial abutment placement and exposure to masticatory stresses. Abutments were placed after a 3-month osseointegration period post‐initial surgical placement of the interosseous stage. 10 edentulous patients, each with 5 mandibular implants were reviewed at 2, 4, 6 and 8 days after abutment placement. Clinical details were assessed and recorded and sulcus fluid collected in microcapillary tubes for a 5‐min period for each abutment. Levels of glycosaminoglycans were assessed using cellulose acetate electrophoresis and densitometric scanning of alcian blue stained strips against known glycosaminoglycan standards. Maximum levels of sulcus fluid (0.3–1.25 /5 min) were evident at 4 days with a decrease towards 8 days. Levels of sulphated glycosaminoglycans were also maximal at 2–4 days (range 0.03–0.126 μg/5 min) and decreased at 6-8 days. Hyaluronan was detected within a similar range of values reaching maximal levels at 4 days and decreasing by 8 days. The results indicate that glycosaminoglycan levels of peri‐implant sulcus fluid is an effective means of measuring and maintaining changes in bone metabolism. The absence of proteodermatan sulphate precludes 1 soft tissues being a source of these markers.     

Titanium allergy in dental implant patients: a clinical study on 1500 consecutive patients

Background: In dentistry, allergic reactions to Ti implants have not been studied, nor considered by professionals. Placing permanent metal dental implants in allergic patients can provoke type IV or I reactions. Several symptoms have been described, from skin rashes and implant failure, to non-specific immune suppression.
Objective: Our objective was to evaluate the presence of titanium allergy by the anamnesis and examination of patients, together with the selective use of cutaneous and epicutaneous testing, in patients treated with or intending to receive dental implants of such material.
Material and methods: Thirty-five subjects out of 1500 implant patients treated and/or examined (2002–2004) were selected for Ti allergy analysis. Sixteen presented allergic symptoms after implant placement or unexplained implant failures [allergy compatible response group (ACRG)], while 19 had a history of other allergies, or were heavily Ti exposed during implant surgeries or had explained implant failures [predisposing factors group (PFG)]. Thirty-five controls were randomly selected (CG) in the Allergy Centre. Cutaneous and epicutaneous tests were carried out.
Results: Nine out of the 1500 patients displayed positive (+) reactions to Ti allergy tests (0.6%): eight in the ACRG (50%), one in the PFG (5.3%)( P =0.009) and zero in the control group. Five positives were unexplained implant failures (five out of eight).
Conclusions: Ti allergy can be detected in dental implant patients, even though its estimated prevalence is low (0.6%). A significantly higher risk of positive allergic reaction was found in patients showing post-op allergy compatible response (ACRG), in which cases allergy tests could be recommended.     

Safety of dental implant surgery in patients undergoing anticoagulation therapy: a prospective case-control study

Objectives: Several studies have described oral surgical procedures in patients receiving anticoagulant therapy, but no prospective studies on dental implant surgery during anticoagulant treatment are currently available, and only a limited number of case reports refer to endosseous dental implant treatment in these patients. In the setting of oral surgery, it has been suggested that anticoagulant treatment is not required when the International Normalized Ratio (INR) is <4 and local haemostatic measures are applied. The purpose of this preliminary study was to evaluate the incidence of bleeding complications following surgical implant therapy in a group of 50 consecutive patients receiving oral anticoagulant therapy (warfarin) without interruption or modifications to their therapy (group A). Materials and methods: One hundred and nine otherwise healthy patients comparable for age, sex, extent and site of the implant surgical procedure formed the control group (group B). In both groups, a standard protocol of local haemostasis, including non‐reabsorbable sutures and compressive gauzes soaked with tranexamic acid, was applied. Surgeons, blind to the group allocation, performed all the procedures in an outpatient setting. Results: Two and three late‐bleeding complications were reported in group A and group B, respectively, without significant difference in the bleeding risk (relative risk = 1.45; P= 0.65; 95% confidence interval 0.2506–8.4271). These complications were managed using a compressive gauze soaked with tranexamic acid at the site of the surgical wound. Conclusion: According to our preliminary results, local haemostasis in dental implant surgery is able to prevent bleeding complications in patients on oral anticoagulants, allowing these surgical procedures to be performed on an outpatient basis. To cite this article:
Bacci C, Berengo M, Favero L, Zanon E. Safety of dental implant surgery in patients undergoing anticoagulation therapy: a prospective case–control study.
Clin. Oral Impl. Res. 22 , 2011; 151–156.
doi: 10.1111/j.1600‐0501.2010.01963.x