Evaluation of peri-implant marginal bone loss using modified abutment connections at various crestal level placements

The purpose of this study was to evaluate crestal bone loss around 282 two-piece implants with straight (n = 193) and platform-switched (n = 89) abutment connections after placement at various crestal levels. Implants were assigned into two groups according to straight and platform-switched abutment connections. Each group was further subdivided into three groups depending on the location (supracrestal, crestal, or subcrestal) of the implant cervical platform. Linear measurements of bone resorption were made from the implant's platform to the first point of bone-to-implant contact at the time of implant placement and 2 years postrestoration. Data were statistically analyzed. Statistically significant differences were found between subgroups in both straight and platform-switched categories. The only nonstatistically significant difference (P = .341) arose when comparing the supra- and subcrestal locations in the straight abutment connection group. The platform-switched group exhibited significantly less bone loss (P = .046) only in subcrestal locations. The platform-switched concept was not beneficial during the overall comparison, but it was for the subcrestal location of the abutment connection. Crestal placement of the implant-abutment connection resulted in higher marginal bone resorption in both straight and platform-switched abutments.     

The role of temperature in the action of local anesthetics: a double study in vitro and in vivo

The purpose of this study was the examination of the role of temperature in the action of lidocaine via electrophysiological recordings on the sciatic nerve of the rat in vitro and in vivo. 20 Male Wistar rats were used in each type of experiment. In vitro, lidocaine shows no statistically significant difference regarding the onset of anesthesia but at the temperature of 25 degrees C it is significantly more potent on the establishment of anesthesia compared to the temperature of 36.5 degrees C. In vivo, lidocaine at the temperature of 4 degrees C is statistically significantly more effective in the establishment and the duration of anesthesia related to the temperature of 20 degrees C.     

Effect of autogenous harvest site location on the outcome of ridge augmentation for implant dehiscences

Treatment planning for the placement of an implant in a site with a thin crestal ridge should address the probability that a buccal dehiscence will result. The aim of the present investigation was to perform guided bone regeneration (GBR) around implants with buccal dehiscences and evaluate the outcomes of using autogenous bone grafts harvested from three different intraoral sites. Forty-six Osseotite implants, 4 mm in diameter, were placed in thin crestal ridges, resulting in an uncovered implant surface from the buccal aspect. The lengths of the buccal dehiscences ranged from 3 to 7 mm as measured from the implant cervix to the most apical extent of the uncovered threads. A standard GBR technique was carried out to augment the bone defect around the buccal implant surface immediately after implant placement. The cases were divided into three groups according to receipt of an autogenous bone graft from the ramus, tuberosity, or mandibular symphysis. In all cases, e-PTFE membranes were used to cover the grafted areas. Grafted sites were exposed after 6 months, membranes were removed, and residual distance between the implant cervix and most uncovered thread was recorded. All grafting materials were able to produce a certain degree of bone regeneration. In terms of bone change level, the three groups were not equal. The mandibular symphysis group exhibited the highest mean bone growth level, followed by the ramus group. The tuberosity produced the poorest result. Mandibular and ramus autogenous bone grafts represent the best choice in materials for GBR procedures around implants, while tuberosity bone grafts can be used as an alternative.     

Bone regeneration around implants using spherical and granular forms of bioactive glass particles

PURPOSE: It has been reported that previous Biogran (3i Implant Innovations, Inc., Palm Beach Gardens, FL) can be converted in vitro into hydroxyapatite (Biogran II) to accelerate new bone formation. The purpose of this study was to evaluate the bone regeneration around implants placed in critical-sized defects in rabbit tibia using granular and spherical forms of Biogran II in regards to implant contact, bone-to-graft contact, bone graft area, and total bone volume. MATERIALS AND METHODS: Twelve adult New Zealand rabbits were used, offering 24 surgical sites (1 in each tibia), where 6-mm round defects were created allowing the homocentric insertion of a screw type experimental implant with Osseotite (3i Implant Innovations, Inc.) surface. Half of the defects (group A) were filled up with spherical and half (group B) with granular forms of Biogran II. Ossix (3i Implant Innovations, Inc.) membranes covered the surgical sites. RESULTS: The histological evaluation after 8 weeks showed new bone formation in both groups, without any statistically significant differences in regards to bone-to-implant contact, bone-to-graft contact, bone graft area, and bone volume. Both dissolution of the outer shell and inner silica gel of the particles were observed mostly in spherical particles. In addition, new bone formation within the protected pouch interconnected with the surrounding new bone was observed exclusively in spherical particles of Biogran II. CONCLUSION: Faster dissolution of both outer and inner portions of spherical particles of Biogran II led to better integration with the surrounding new bone during an 8-week period of healing.     

Clinical evaluation of immediate loaded upper anterior single implants

Among the guidelines to be followed in the selection of patients who are suitable for treatment with dental implants, there must be accurate assessment and evaluation of the factors that will lead to a functionally long-lasting and aesthetically pleasing result. The latter, which includes the maintenance and development of hard and soft tissues, undoubtedly presents a significant challenge in clinical implantology. The purpose of this study was the clinical evaluation of the methods currently available for the aesthetic restoration of the anterior maxilla using single implants that were loaded immediately. Forty-three patients were treated over 2 years using single implants with immediate nonfunctional loading. The patients were divided into two groups, groups A and B (i.e., immediate implant installation and late implant installation, respectively). Guided bone regeneration techniques were performed in 10 patients in group A and three patients in group B and involved buccal fenestrations orbuccal dehiscence around the implants. The parameters studied were: 1) the anatomical requirements necessary in selecting such patients and the limitations that might affect (to a lesser or greater degree) the desired results; 2) the planning and application of surgical techniques, both with immediate and short-term delay postextraction implantation, as well as the placing of implants in areas with long-term dental loss; and c) the results, after radiologic and clinical follow-up visits every 6 months, for an overall period of 2 years. No implant failure was recorded, and the therapeutic procedures were considered completely successful in all cases, without significant radiographic peri-implant marginal bone loss (i.e., average bone loss in mm +/- SD, 0.75 +/- 1.05 in group A and 0.875 +/- 0.625 in group B) or significant clinical differences in peri-implant sulcus depth (average difference in mm +/- SD, 0.3 +/- 0.2 in group A and 0.4 +/- 0.375 in group B). In cases where guided bone regeneration techniques were applied, the results were considered successful and final, and the aesthetic results were deemed more satisfactory than was expected. The procedure was successful in all cases in terms of both osseointegration and aesthetics. The use of dental implants with nonfunctional loading in particularly sensitive aesthetic areas is recommended unreservedly, given the existence of the anatomical requirements, good initial stability, and the absence of extensive bone loss in the area receiving the implant. In addition, application of this treatment method leads, within a very short time, to a particularly successful aesthetic result, reducing the number of surgeries and the duration of treatment.     

Safety of dental extractions during uninterrupted single or dual antiplatelet treatment

Optimal dental management in patients on long-term antiplatelet treatment is not clearly defined. Antiplatelet discontinuation increases the risk of thrombotic complications, whereas uninterrupted antiplatelet therapy, which is the currently recommended approach, is assumed to increase the bleeding hazard after dental procedures. We sought to prospectively compare the risk of immediate and late postextraction bleeding in patients receiving uninterrupted single or dual antiplatelet therapy. We recruited 643 consecutive patients referred for dental extractions. In total 111 (17.3%) were on clinically indicated antiplatelet therapy: aspirin (n = 42), clopidogrel (n = 36), and aspirin and clopidogrel (n = 33). Controls (n = 532, 82.7%) were not on antiplatelet treatment. Immediate and late bleeding complications were recorded. Compared to controls the risk of prolonged immediate bleeding was higher in patients on dual antiplatelet therapy (relative risk [RR] 177.3, 95% confidence interval [CI] 43.5 to 722, p <0.001) but not in patients on aspirin alone (RR = 6.3, 95% CI 0.6 to 68.4, p = 0.2) or clopidogrel alone (RR = 7.4, 95% CI 0.7 to 79.5, p = 0.18); however, all immediate bleeding complications in all treatment groups were successfully managed with local hemostatic measures. No patient developed any late hemorrhage. In conclusion, dental extractions may be safely performed in patients receiving single or dual antiplatelet therapy when appropriate local hemostatic measures are taken, thus averting thrombotic risk of temporary antiplatelet discontinuation.