BACKGROUND & AIMS: STATEMENT OF PROBLEM:The bond strength of porcelain to titanium is insufficient to provide a clinically acceptable alternative to existing alloys for metal ceramic restorations. PURPOSE:The purpose of the study was to investigate the effect of gold coating on the adhesion of porcelain to titanium. MATERIAL AND METHODS:Forty titanium plates (25 × 8 × 1 mm) were prepared by casting and machining procedures to make 2 groups of each type (n=10). All plates were subjected to airborne-particle abrasion with alumina powder. One of each of the cast and machined groups was gold sputtered. A layer of porcelain was built up onto the titanium plates of all groups with a conventional technique. A precrack was created at the center of the specimen. Specimens were then subjected to a 4-point bending test with a universal testing machine. The load recorded from the test was used to determine adhesion in terms of the strain energy release rate (G value). The data were analyzed with ANOVA and post hoc testing (α=.05). The interfacial area of the tested specimen was then examined with scanning electron microscopy. RESULTS:The G values of the gold-sputtered groups were significantly higher than those of the uncoated groups for both cast and machined groups (P<.05). No significant differences were noted within the groups. CONCLUSIONS:The adhesion between porcelain and titanium was significantly improved when titanium was sputter coated with gold in both the cast and machined groups.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:Immediate loading of osseointegrating implants shortens the treatment time and makes it possible to give the patient an esthetic appearance during the whole treatment period. A previous retrospective clinical study showed a success rate of 94.2% after 1 year of immediate loading of fixed partial constructions in the maxilla supported by machined-surface implants. The recently introduced Brånemark System TiUnite (Nobel Biocare AB, Gothenburg, Sweden) surface has been shown to better maintain primary implant stability and to help achieve secondary stability earlier compared with the machined surface. PURPOSE:The aim of the present study was to compare TiUnite and machined-surfaced Brånemark System implants when applying immediate loading of partial fixed bridges in the posterior mandible. MATERIALS AND METHODS:Forty-four patients were randomized for test and control therapy. In the test group, 22 patients received 66 Brånemark System TiUnite surface implants supporting 24 fixed partial bridges, all of which were connected on the day of implant insertion. In the control group, 22 patients received 55 Brånemark System machined-surface implants supporting 22 fixed partial bridges, which also were connected on the day of implant insertion. All constructions were two- to four-unit bridges. Bone quality and quantity were assessed. Radiographic examinations were performed on the day of surgery/loading and at the 1-year follow-up visit. RESULTS:Three TiUnite and eight machined-surface implants failed during the first 7 weeks of loading. This resulted in a cumulative success rate of 95.5% for TiUnite surface implants after 1 year of prosthetic load in the posterior mandible. The corresponding cumulative success rate for machined-surface implants was 85.5%. When using the machined-surface implants, the number of failed implants was significantly higher in smokers and in bone quality 4 sites. Such findings were not seen with the use of TiUnite implants, despite the fact that there were more smokers and more implants placed in bone quality 4 in this group. The marginal bone resorption after 1 year of loading was on average 0.9 mm (SD 0.7 mm) with the TiUnite implants and 1.0 mm (SD 0.9 mm) with the machined implants. CONCLUSIONS:The present study demonstrated a 10% higher success rate following immediate loading of partial fixed bridges in the posterior mandible supported by TiUnite surface implants compared with success with machined implants. When using the machined implants, the number of failed implants was significantly higher in smokers and in bone quality 4 sites. Such findings were not seen following the use of TiUnite implants.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:The surface roughness of a dental implant affects the epithelial wound healing process and may significantly enhance implant prognosis. PURPOSE:We explored the influence of surface roughness on peri-implant epithelium (PIE) sealing and down-growth by comparing machine-surfaced (Ms) and rough-surfaced (Rs) implants. MATERIALS AND METHODS:(1) Maxillary first molars were extracted from rats and replaced with Ms or Rs implants. (2) We also compared changes in the morphology of cultured rat oral epithelial cells (OECs) grown on Ms or Rs titanium (Ti) plates. RESULTS:(1) After 4 weeks, the PIE around Ms and Rs implants showed a similar structure to junctional epithelium (JE). At 16 weeks, Rs implants appeared to form a weak epithelial seal at the tissue-implant interface and exhibited markedly less PIE down-growth than Ms implants but was deeper than that observed in natural teeth. (2) We observed less expression of adhesion proteins in OECs cultured on Rs plates than in cells grown on Ms plates. Additionally, cell adherence, migration, and proliferation on Rs plates were lower, whereas apoptosis was reduced on Ms plates. CONCLUSION:Ms implants are a better choice for integration with an epithelial wound healing process.

背景与目标：

BACKGROUND & AIMS: PURPOSE:A single-blind randomized controlled split-mouth trial was performed to compare the 36-month outcomes of machined and titanium oxide-anodized (ADZ) dental implant surfaces immediately loaded with fixed partial dentures in the posterior mandible. MATERIALS AND METHODS:Ten patients with bilateral partial edentulism in the posterior mandible received 42 implants; 20 were placed on the test side (ADZ) and 22 were placed on the control (machined) side. The implants were loaded within 24 hours after placement. Changes in the radiographic bone level (RBL) were measured on standardized periapical films at baseline, 12 months, and 36 months. The mean changes in RBL were compared using a paired t test, and the mean changes in RBL with regard to implant position and implant surface type were compared via two-way analysis of variance. RESULTS:After 36 months of functional loading, the overall cumulative success rate for all implants was 95%. The mean change in RBL at 36 months was 0.35 mm and 0.32 mm for ADZ and machined implants, respectively (not statistically significantly different between groups; P = .88). A reduction in RBL was observed for both machined and ADZ implants between 12 and 36 months, but only the machined implants demonstrated a statistically significant decrease in RBL during the observation period. CONCLUSIONS:No statistically significant differences in RBL change were found between machined and ADZ implant surfaces after 36 months in function, and both surfaces demonstrated minimal marginal bone remodeling. As such, immediate loading of ADZ and machined dental implants supporting fixed partial dentures may be a suitable long-term treatment option in the posterior mandible.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:Experimental studies demonstrated that peri-implant crestal hard and soft tissues are significantly influenced in their apico-coronal position by the rough/smooth implant border as well as the microgap/ interface between implant and abutment/restoration. The aim of this study was to evaluate radiographically the crestal bone level changes around two types of implants, one with a 2.8 mm smooth machined coronal length and the other with 1.8 mm collar.

METHODS:In 68 patients, a total of 201 non-submerged titanium implants (101 with a 1.8 mm, 100 with a 2.8 mm long smooth coronal collar) were placed with their rough/smooth implant border at the bone crest level. From the day of surgery up until 3 years after implant placement crestal bone levels were analyzed digitally using standardized radiographs.

RESULTS:Bone remodeling was most pronounced during the unloaded, initial healing phase and did not significantly differ between the two types of implants over the entire observation period (P >0.20). Crestal bone loss for implants placed in patients with poor oral hygiene was significantly higher than in patients with adequate or good plaque control (P <0.005). Furthermore, a tendency for additional crestal bone loss was detected in the group of patients who had been diagnosed with aggressive periodontitis prior to implant placement (P = 0.058). In both types of implants, sand-blasted, large grit, acid-etched (SLA) surfaced implants tended to have slightly less crestal bone loss compared to titanium plasma-sprayed (TPS) surfaced implants, but the difference was not significant (P >0.30).

CONCLUSION:The implant design with the shorter smooth coronal collar had no additional bone loss and may help to reduce the risk of an exposed metal implant margin in areas of esthetic concern.

背景与目标： 背景 : 实验研究表明，粗糙/光滑的植入物边界以及植入物与基台之间的微间隙/界面对植入物周围的软硬组织和软组织的顶冠状位置有显着影响/修复。这项研究的目的是评估两种类型的植入物周围的x线骨水平变化，一种具有2.8毫米光滑的加工冠状长度，另一种具有1.8毫米的项圈。
方法 : 在68例患者中，总共放置了201个非浸没的钛植入物 (101有1.8毫米，100有2.8毫米长的光滑冠状项圈)，其粗糙/光滑的植入物边界位于骨顶水平。从手术当天到种植体放置后3年，使用标准化x光片对牙体骨水平进行数字分析。
结果 : 在卸载过程中，骨骼重塑最为明显，在整个观察期内，两种类型的植入物之间的初始愈合阶段没有显着差异 (P >0.20)。口腔卫生不良的患者放置的种植体的Crestal骨丢失显着高于斑块控制充分或良好的患者 (P <0.005)。此外，在植入之前被诊断出患有侵袭性牙周炎的患者组中检测到额外的crest骨丢失的趋势 (P = 0.058)。在这两种类型的植入物中，与钛等离子喷涂 (TPS) 表面植入物相比，喷砂，大砂砾，酸蚀 (SLA) 表面植入物的crest骨丢失往往略少，但差异不显著 (P >0.30)。
结论 : 具有较短光滑冠状项圈的植入物设计没有额外的骨质流失，并且可能有助于降低美学领域中金属植入物边缘暴露的风险。

BACKGROUND & AIMS: PURPOSE:This study evaluated the effect of the platform-switching phenomenon, the use of a smaller diameter abutment on a larger diameter implant platform. Clinical and histological outcomes of the periimplant mucosa around titanium abutments in a nonsubmerged implant were evaluated. MATERIALS AND METHODS:Ten healthy adult patients, ranging from 27 to 65 years, participated in the study. A minimum of 2 endosseous implants with immediate abutment connection was placed per patient, 1 conventional and 1 platform-switched abutment. All sites for implant placement had an adequate zone of keratinized mucosa before surgical intervention. RESULTS:No clinical signs of inflammation were observed in the periimplant soft tissue mucosa, and healing was uneventful throughout the study period. Histological findings showed abnormally thick stratified squamous epithelium for both groups with few inflammatory cells in the connective tissue and none on the surface of the epithelium. CONCLUSION:Histological findings for both conventional and platform-switched implant-abutment configurations showed a similar composition of the soft tissue. These findings were in direct agreement with previous studies.

背景与目标：

BACKGROUND & AIMS: OBJECTIVES:The aim of this study was to evaluate the influence of different titanium zirconium (TiZr) alloy surfaces on primary human gingival fibroblasts (HGF) for improved soft tissue integration of dental implants. METHODS:TiZr polished, machined and machined+HCl/H2SO4 acid-etched surfaces were modified by cathodic polarization and/or HNO3/HF acid etching. Contact angle of surfaces was measured. The influence of modified TiZr surfaces on HGF was evaluated through the analysis of cell number, morphology, recovery after a wound (wound healing assay) and the expression of several genes, including matrix metalloproteinase-1 (MMP1) and metallopeptidase inhibitor-1 (TIMP1). RESULTS:Modification of TiZr surfaces decreased its hydrophilicity. Hydride implementation on TiZr surfaces via cathodic polarization increased TIMP1 expression and decreased MMP1/TIMP1 mRNA ratio. Cathodic polarization of machined surfaces promoted cell attachment. Cells on machined and machined+cathodic polarization surfaces grew aligned to the microgrooves whereas on all polished surfaces they grew randomly. Acid etching of polished and machined surfaces did not improve HGF function. CONCLUSIONS:Hydride implementation on TiZr machined surfaces may be used as new dental implant material for improved soft tissue integration. CLINICAL SIGNIFICANCE:Enhancing dental implant surfaces' bioactivity by hydride implementation may promote soft tissue attachment and sealing around the implant and reduce peri-implantitis related to ECM-destruction compared with conventional machined surfaces.

背景与目标：

BACKGROUND & AIMS: PURPOSE:To compare the early bone response to implants with dual acid-etched (DAE) and machined (MA) surface, when placed in the posterior human maxilla. MATERIALS AND METHODS:Fourteen patients received 2 implants in the posterior maxilla: 1 DAE and 1 MA. After 2 months, the implants were retrieved for histologic/histomorphometric evaluation. The bone-to-implant contact (BIC%), bone density in the threaded area (BDTA%), and the bone density (BD%) were calculated. The Wilcoxon matched-pairs signed rank test was used to evaluate differences (BIC%, BDTA%, and BD%) between the surfaces. RESULTS:In the MA implants, a mean (±SD) BIC%, BDTA%, and BD% of 21.76 (±12.79), 28.58 (±16.91), and 21.54 (±11.67), respectively, was reported. In the DAE implants, a mean (±SD) BIC%, BDTA%, and BD% of 37.49 (±29.51), 30.59 (±21.78), and 31.60 (±18.06), respectively, was reported. Although the mean BIC% of DAE implants value was almost double than that of MA implants, no significant differences were found between the 2 groups with regard to BIC% (P = 0.198) and with regard to BDTA% (P = 0.778) and BD% (P = 0.124). CONCLUSIONS:The DAE surface increased the periimplant endosseous healing properties in the native bone of the posterior maxilla.

背景与目标：

BACKGROUND & AIMS: PURPOSE:To evaluate the biomechanical fixation, bone-to-implant contact (BIC), and bone morphology of screw-type root-form implants with healing chambers with as-machined or dual acid-etched (DAE) surfaces in a canine model. MATERIALS AND METHODS:The animal model included the placement of machined (n = 24) and DAE (n = 24) implants along the proximal tibiae of six mongrel dogs, which remained in place for 2 or 4 weeks. Following euthanasia, half of the specimens were subjected to biomechanical testing (torque to interface failure) and the other half were processed for histomorphologic and histomorphometric (%BIC) assessments. Statistical analyses were performed by one-way analysis of variance at the 95% confidence level and the Tukey post hoc test for multiple comparisons. RESULTS:At 4 weeks, the DAE surface presented significantly higher mean values for torque to interface failure overall. A significant increase in %BIC values occurred for both groups over time. For both groups, bone formation through the classic appositional healing pathway was observed in regions where intimate contact between the implant and the osteotomy walls occurred immediately after implantation. Where contact-free spaces existed after implantation (healing chambers), an intramembranous-like healing mode with newly formed woven bone prevailed. CONCLUSIONS:In the present short-term evaluation, no differences were observed in BIC between groups; however, an increase in biomechanical fixation was seen from 2 to 4 weeks with the DAE surface.

背景与目标：

BACKGROUND & AIMS: :The bone formation around titanium implants with varied surface properties was investigated after 1 year in rabbits. Machined and electropolished samples with and without thick, anodically formed surface oxides were prepared, surface characterized and inserted in the cortical bone of rabbits. Scanning electron microscopy, scanning Auger electron spectroscopy and atomic force microscopy revealed marked differences in oxide thickness, surface topography and roughness, but no significant differences in surface chemical composition between the different groups of implants. Light microscopic morphology and morphometry showed that all implants were in contact with bone and had a large proportion of bone within the threads. There were no significant differences between the differently prepared implant groups. Our study shows that a high degree of bone contact and bone formation is achieved after 1 year with titanium implants which are modified with respect to oxide thickness and surface topography. There is no indication that a reduction of surface roughness, which in the initial phase decreases the rate of bone formation, had any influence on the amount of bone after 1 year in rabbit cortical bone.

背景与目标： : 在兔子中研究了具有不同表面特性的钛植入物周围的骨形成。制备有或没有厚的阳极氧化表面氧化物的机加工和电抛光样品，表面表征并插入兔子的皮质骨中。扫描电子显微镜，扫描俄歇电子能谱和原子力显微镜显示出氧化物厚度，表面形貌和粗糙度的显着差异，但不同组的植入物之间的表面化学成分没有显着差异。光学显微镜形态和形态计量学表明，所有植入物均与骨骼接触，并且螺纹内的骨骼比例很大。不同制备的植入物组之间没有显着差异。我们的研究表明，使用钛植入物在1年后可以实现高度的骨接触和骨形成，钛植入物在氧化物厚度和表面形貌方面进行了改性。没有迹象表明表面粗糙度的降低 (在初始阶段会降低骨形成速率) 对兔皮质骨1年后的骨量有任何影响。

BACKGROUND & AIMS: AIM:To evaluate the surface and microstructural alterations of new and used HyFlex EDM prototypes and to test their fatigue resistance. METHODOLOGY:Fifteen HyFlex EDM prototypes were used for in vitro instrumentation of severely curved root canals. Surface and microstructural characteristics of new and used files were compared by ESEM analysis equipped with energy dispersive X-ray spectrophotometry (EDS) and optical metallographic imaging. Usage-induced degradation was assessed. Thirty additional HyFlex EDM prototypes and 20 standard manufactured HyFlex CM files were subjected to cyclic fatigue tests. Time to fracture was recorded, and results were validated using the Kruskal-Wallis test (α-level 0.05). Fatigued files were analysed by ESEM for fractographic evaluation. RESULTS:Surface and microstructural characterization of EDM prototypes revealed the typical spark-machined surface of a NiTi EDM alloy. No fractures were registered during root canal instrumentation. No evident surface alterations and minor degradation were observed between new and used instruments. The metallographic analysis of new and used files disclosed a homogeneous structure, mostly composed of lenticular martensite grains, and some residual austenite. The cyclic fatigue test showed an increase of fatigue resistance up to 700% on the EDM compared to CM files. CONCLUSIONS:Spark-machined peculiar surface is the main feature of HyFlex EDM. Low degradation was observed after multiple canal instrumentations. Prototypes exhibited surprising high values of cyclic fatigue resistance and a safe in vitro use in severely curved canals.

背景与目标：

BACKGROUND & AIMS: :The effect of preparation design and the physical properties of the interface lute on the restored machined ceramic crown-tooth complex are poorly understood. The aim of this work was to determine, by means of three-dimensional finite element analysis (3D FEA) the effect of the tooth preparation design and the elastic modulus of the cement on the stress state of the cemented machined ceramic crown-tooth complex. The three-dimensional structure of human premolar teeth, restored with adhesively cemented machined ceramic crowns, was digitized with a micro-CT scanner. An accurate, high resolution, digital replica model of a restored tooth was created. Two preparation designs, with different occlusal morphologies, were modeled with cements of 3 different elastic moduli. Interactive medical image processing software (mimics and professional CAD modeling software) was used to create sophisticated digital models that included the supporting structures; periodontal ligament and alveolar bone. The generated models were imported into an FEA software program (hypermesh version 10.0, Altair Engineering Inc.) with all degrees of freedom constrained at the outer surface of the supporting cortical bone of the crown-tooth complex. Five different elastic moduli values were given to the adhesive cement interface 1.8GPa, 4GPa, 8GPa, 18.3GPa and 40GPa; the four lower values are representative of currently used cementing lutes and 40GPa is set as an extreme high value. The stress distribution under simulated applied loads was determined. The preparation design demonstrated an effect on the stress state of the restored tooth system. The cement elastic modulus affected the stress state in the cement and dentin structures but not in the crown, the pulp, the periodontal ligament or the cancellous and cortical bone. The results of this study suggest that both the choice of the preparation design and the cement elastic modulus can affect the stress state within the restored crown-tooth complex.

背景与目标： : 制备设计和界面琵琶的物理性能对还原的机加工陶瓷冠齿复合体的影响知之甚少。这项工作的目的是通过三维有限元分析 (3D FEA) 确定牙齿准备设计和水泥弹性模量对水泥加工陶瓷冠齿复合体应力状态的影响。使用micro-CT扫描仪对人类前磨牙的三维结构进行了数字化处理，该三维结构用粘合的机械加工陶瓷牙冠进行了修复。创建了修复牙齿的准确，高分辨率，数字复制模型。使用3种不同弹性模量的水泥对两种具有不同咬合形态的制备设计进行了建模。交互式医学图像处理软件 (mimics和专业CAD建模软件) 用于创建复杂的数字模型，其中包括支撑结构; 牙周膜和牙槽骨。将生成的模型导入到FEA软件程序 (hypermesh版本10.0，Altair Engineering Inc.) 中，所有自由度都被约束在冠齿复合体的支撑皮质骨的外表面。对粘合剂水泥界面给出了1.8GPa，4GPa，8GPa，18.3gpa和40GPa的五个不同的弹性模量值; 四个较低的值代表了当前使用的固井lute，并将40GPa设置为极高值。确定了模拟施加载荷下的应力分布。制备设计证明了对恢复的牙齿系统的应力状态的影响。水泥弹性模量会影响水泥和牙本质结构中的应力状态，而不会影响牙冠，牙髓，牙周膜或松质和皮质骨的应力状态。这项研究的结果表明，制备设计的选择和水泥弹性模量都会影响修复后的冠齿复合体内的应力状态。

BACKGROUND & AIMS: OBJECTIVES:This study evaluated the effect of a chromium interlayer deposited by electroplating on the adhesion between titanium and porcelain by means of strain energy release rate (G-value (J/m(2)) or interfacial toughness). METHODS:Seventy rectangular specimens of commercially pure titanium (CP Ti) plates grade II (8 mm x 30 mm x 1.5 mm) were prepared. The specimens were divided into seven groups according to the electroplating treatment; Gr 1 (control without electroplating, n=10); Gr 2 (5% (w/v) chromium nitrate solution for 30 min, n=10); Gr 3 (5% (w/v) chromium nitrate solution for 60 min, n=10); Gr 4 (5% (w/v) chromium nitrate solution for 120 min, n=10); Gr 5 (10% (w/v) chromium nitrate solution for 30 min, n=10); and Gr 6 (10% (w/v) chromium nitrate solution for 60 min, n=10) and Gr 7 (10% (w/v) chromium nitrate solution for 120 min, n=10). Each group was further equally divided into two subgroups according to the type of porcelain used. Two titanium-porcelains (Vita Titankeramik and Triceram) were applied to each subgroup (n=5). The G-value was measured with a four-point bending configuration. Following fracture testing, specimens were examined with a scanning electron microscope (SEM). Data were analysed using ANOVA and Tukey's test. RESULTS:Adhesion values were significantly affected by the type of electroplating treatment (P<0.05) and by the type of porcelain (P<0.05). The CP Ti/Vita Titankeramik (0.5h 5% (w/v), 1h 5% (w/v) and 0.5h 10% (w/v)) groups showed the highest G-value (36.94+/-3.25, 38.87+/-7.91 and 37.22+/-5.76J/m(2)) amongst their groups. The CP Ti/Triceram (0.5h 5% (w/v) and 0.5h 10% (w/v)) groups (26.72+/-4.36 and 26.94+/-3.52J/m(2)) were statistically significantly different from the control group (14.99+/-1.50J/m(2)) (P<0.05). A definitive relationship was found between Cr film thickness and G-value for both porcelain materials. CONCLUSION:Adhesion between porcelain and CP Ti can be improved by the use of chromium interlayer prior to porcelain firing.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:Positive effects on the clinical outcome of moderately rough implant surfaces are described. Intercomparison of clinical data, however, is rarely found. PURPOSE:The aim of this study was to compare the clinical results of two macroscopically identical implants, the one with a turned, machined and the other with an etched surface. MATERIALS AND METHODS:In a retrospective cohort study, the included implants followed the criteria: standard surgical protocol, >12 months in situ; minimally rough self-threading implants with a turned, machined surface (Mk II Nobel Biocare AB, Göteborg, Sweden], n=210); etched implants of the same macrodesign (3i Implant Innovations Inc., Palm Beach Gardens, FL, USA], n=151), length > or = 10 mm. Clinical data and implant success were rated. Resonance frequency analysis (RFA) and Periotest (Siemens AG, Bensheim, Germany) were measured and related to the corresponding implant survival rate in the respective group. RESULTS:The total number of implants was 361, of which 264 (73%) were subject to clinical reexamination. RFA and Periotest could be recorded in 25% of the implants. Neither clinically relevant nor statistically significant differences between the surface designs were found in the RFA (64 +/- 8.6 vs 63 +/- 9.7), in Periotest (-2 +/- 3.3 vs -1 +/- 5.1), and in mean survival periods (49 months, 95% confidence interval CI]: 46-51 months, for the turned vs 46 months, 95% CI: 43-49 months, for the double-etched implant). After osteoplastic procedures, a significantly higher rate of implant losses in the turned, machined implant group was observed (17 vs 1) with a mean survival period of 43 (40-46) months for the turned and 46 (45-48) months for the double-etched implants. CONCLUSION:No difference between implants with two different minimally rough surfaces was found. A positive effect of surface roughness is observed in poor quality bone, but the pivotal proof of this effect is still lacking.

背景与目标：

BACKGROUND & AIMS: AIMS:To evaluate the checkerboard DNA-DNA hybridization method for detection and quantitation of bacteria from the internal parts of dental implants and to compare bacterial leakage from implants connected either to cast or to pre-machined abutments. MATERIALS AND METHODS:Nine plastic abutments cast in a Ni-Cr alloy and nine pre-machined Co-Cr alloy abutments with plastic sleeves cast in Ni-Cr were connected to Branemark-compatible implants. A group of nine implants was used as control. The implants were inoculated with 3 microl of a solution containing 10(8) cells/ml of Streptococcus sobrinus. Bacterial samples were immediately collected from the control implants while assemblies were completely immersed in 5 ml of sterile Tripty Soy Broth (TSB) medium. After 14 days of anaerobic incubation, occurrence of leakage at the implant-abutment interface was evaluated by assessing contamination of the TSB medium. Internal contamination of the implants was evaluated with the checkerboard DNA-DNA hybridization method. RESULTS:DNA-DNA hybridization was sensitive enough to detect and quantify the microorganism from the internal parts of the implants. No differences in leakage and in internal contamination were found between cast and pre-machined abutments. Bacterial scores in the control group were significantly higher than in the other groups (P<0.05). CONCLUSION:Bacterial leakage through the implant-abutment interface does not significantly differ when cast or pre-machined abutments are used. The checkerboard DNA-DNA hybridization technique is suitable for the evaluation of the internal contamination of dental implants although further studies are necessary to validate the use of computational methods for the improvement of the test accuracy.

背景与目标：