Clinical Performance of 170 Frictional Morse Taper Implants: 2 Years Follow-Up.

This study evaluated the clinical survival rates of 170 Morse taper implants through clinical and mechanical parameters in different therapeutic approaches such as single crowns, fixed partial prostheses, and fixed full-arch prostheses. Patients referred to the Center on Education and Research on Dental Implants from May 2017 to July 2018 with the indication for dental implant therapy, aged >18 years, without periodontal disease, recent evidence of inflammatory activity or other oral disorders, current pregnancy, uncontrolled diabetes mellitus or heavy smoking habit were included in this study. After 12 weeks of healing since the implants were placed in the mandible and after 16 weeks following implants placed in the maxilla, patients returned to the Center for prosthetic rehabilitation. After implant therapy, all patients underwent periodical, clinical, and prosthetic examinations every 6 months. Prosthetic restorations involved 109 fixed reconstructions in function. Few prosthetic complications were reported (6.55%). Twenty implants were rehabilitated with cemented prostheses; from those, 1 crown suffered a loss in retention/decementation. Of the 148 implants rehabilitated with screwed-retained prostheses, 6.76% suffered prosthetic screw loosening. The cumulative implant survival rate was 98.2%. When peri-implant tissue health was evaluated, the keratinized mucosa band appeared related to peri-implant tissue stability. Thus, Morse taper implants represented a successful procedure for implant rehabilitation, with a high cumulative implant survival rate, low prevalence of biological and prosthetic complications, and good stability of peri-implant tissues over the assessed period.

Bacterial leakage in external hexagon implants with and without the interposition of a sealing-connector.

PURPOSE: To investigate whether the interposition of a sealing-connector was able to reduce the bacterial leakage in external hexagon implants. METHODS: 20 implants with external hexagon connection were used. Ten Test implant-abutment assemblies were connected with the interposition of a sealing-connector molded in the exact shape of the two opposed surfaces. Ten Control implant-abutment assemblies were connected with no sealing-connector interposed. Two types of bacteria were introduced into the internal portion of the implant, before placing the connector. The study lasted 28 days. RESULTS: All control specimens, seeded with P. aeruginosa (PA) and A. actynomycetemcomitans (AA), showed contamination of the culture medium, indicative of microbial leakage. In the Test specimens, three instances of contaminated specimens were found in the samples seeded with PA and two contaminated specimens in the ones seeded with AA, for a total of five contaminated samples out of 10. The use of the sealing-connector was able to prevent bacterial leakage in half of the samples (50%). The leakage in both groups occurred mainly in the last week of the experiment. Probably, a longer period, under the conditions of this experiment, is necessary for the migration of the bacteria, and, furthermore, an observation period of 7 or 14 days may not be enough to show microbial contamination. CLINICAL SIGNIFICANCE: Using an interface under in vitro non-loading experimental conditions, could sometimes (50%) prevent bacterial microleakage and thus possibly the risk of peri-implant site infection. Moreover, less bone resorption and the maintenance of soft tissues and esthetics might be achieved in those cases where bacterial leakage does not occur.

Influence of immediate/delayed implant placement and implant platform on the peri-implant bone formation.

AIM: To determinate the influence of the timing and position of the implant placement, as well as the presence and absence of a buccal gap, associated with different implant platforms on bone formation around implants. METHODS AND MATERIALS: In a first surgical stage, two premolars in one side of the mandibular arch of 07 mongrel dogs were extracted. After a 120-day healing period, a second-stage surgery was performed, in which a full flap was raised and two implants were installed. At this same stage, two contralateral premolars were extracted and two immediate implants were placed into the fresh sockets, through the "palatal approach technique" without flap elevation, totaling four implants per animal. The 28 installed implants constituted groups according to the timing (Immediate or delayed) of placement and the type of surface treatment. After 4 months, samples were collected and histomorphometric analysis was performed to determinate buccal surface BIC, lingual surface BIC, total BIC, buccal area, and lingual area of all implants. Kruskal-Wallis and pared Wilcoxon (P < 0.05) tests were performed for statistical analysis. RESULTS: After 4-month healing period, the groups of immediate implants presented better BIC scores, mainly on the buccal surface. Data also suggest better bone area formation around the implants of these same groups. Concerning the type of implant platform, better results were found using Morse taper. CONCLUSION: The flapless technique with "palatal approach," Morse taper implants, and immediate implant placement all have favorable influence on the bone formation around the implants.

Biological response to porcine xenograft implants: an experimental study in rabbits.

PURPOSE: The aim of this study was to evaluate the effect of a new porcine biomaterial and collagen paste in 20 New Zealand rabbits. MATERIALS AND METHODS: Forty implants using a porcine xenograft made up of 80% corticocancellous collagenated bone particles of ≤300 µm in size were placed in the proximal metaphyseal area of both tibiae. Four periods of time were formed: 1h, 5, 8, and 15 months. After implantation, an anteroposterior and lateral radiological study was carried out. Samples were sectioned at 5 µm and stained using hematoxylin-eosin, Masson's trichromic, and Gordon-Switt reticulin stains. RESULTS: These results confirmed the biocompatibility of this porcine biomaterial-collagen paste; only a few, occasional macrophages and scattered lymphocytes were observed. No fibrosis was observed between the implants and the bone. Moreover, the material was osteoconductive acting as a "scaffold" for bone cells, and there was a progressive increase in bone growth in and around the implants. CONCLUSION: This new porcine biomaterial-collagen paste seemed to be biocompatible, bioresorbable, and osteoconductive.

Single-tooth Morse taper connection implants after 1 year of functional loading: a multicentre study on 302 patients.

PURPOSE: This prospective clinical study evaluated the survival rate and the implant-crown success of 314 Morse taper connection implants, used for single-tooth replacement, after 1 year of functional loading. MATERIALS AND METHODS: Over a 4-year period (January 2003 to January 2007), 314 implants (168 maxilla, 146 mandible) were inserted in 302 patients (128 males, 174 females, aged between 23 to 79 years) in six different clinical centres. The sites included anterior (n = 118) and posterior (n = 196) teeth. To evaluate implant-crown success, the following clinical, prosthetic and radiographic parameters were assessed: modified plaque index (mPI), modified sulcus bleeding index (mBI), probing depth (PD), distance from the implant crown margin to the coronal border of the peri-implant mucosa (DIM), width of keratinised mucosa (KM), prosthesis function, and the distance between the implant shoulder and first crestal bone-implant contact (DIB). Success criteria included: absence of suppuration and mobility, PD<5.0 mm, absence of prosthetic complications, absence of continuous peri-implant radiolucency, and DIB<1.5mm after 1-year of functional loading. Prosthetic restorations were all-ceramic (n=116) and metal-ceramic (n=198) crowns. RESULTS: The implant survival rate was 98.4% (5 implant losses, 1 drop-out). A few prosthetic complications (0.6% implant-abutment loosening) were reported. The mean DIB was 0.887 + or - 0.308mm. Among the survived implants (308), four did not fulfill the success criteria, giving an implant-crown success of 98.7%. CONCLUSION: The use of Morse taper connection implants represents a successful procedure for single-tooth replacement, in the anterior and posterior areas of both arches. The high mechanical stability amy reduce prosthetic complications.