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Objective: To compare marginal changes at bone- level implants restored with screw- retained implant prosthesis with or without intermediate standardised abutments, after 1 year of follow-up.Materials and Methods: Thirty- six partially edentulous patients received 72 implants. Each patient received 2 implants and a 2- to 4- unit screw- retained implant- prosthesis. The test group received implants consisting of a screw- retained prosthesis connected directly to the implant shoulder, while the prostheses in the control group were con-nected through a 3- mm standardised intermediate abutment. Clinical and radiological data were recorded at baseline and at 3, 6 and 12 months in follow-up visits.Results: At 12 months, the marginal bone loss was 0.17 ± 0.24 mm for the test group (19 patients) and 0.09 ± 0.15 mm for the control group (17 patients), with no statistically significant differences (p> .05). The mean probing pocket depth was 2.96 mm ± 0.46 for the test group and 2.86 ± 0.62 mm for the control group. The test and control groups showed bleeding on probing levels of 18.86 ± 14.12% and 13.73 ± 17.66%, re-spectively. All patients scored below 25% on the plaque index levels.Conclusions: Restoration of bone- level implants with fixed screw- retained partial prostheses with or without intermediate abutments presented similar radiographic and clinical outcomes after 1 year

Objectives: To develop a new preclinical model to study early implant loss, where local infection conditions would impair the implant osseointegration. Materials and methods: Forty-eight smooth, 2.9-mm diameter experimental implants were placed in the mandible of 8 beagle dogs (3 in each side). In half of the animals (test group, n = 24 implants), the implants received ligatures around the implant-abutment connection. In the other half, no ligatures were placed (control group, n = 24 implants). Four weeks later, implants were extracted in a flapless approach and standard 3.3-mm diameter SLActive implants were placed into the same osteotomy site without any further drilling. Eight weeks after the second implantation, animals were sacrificed and analyzed in terms of implant survival. Results: After 8 weeks of healing, 4 implants were lost in the control group and 14 in the test group. This corresponded to a 17.4% of early implant loss in the control group and 58.3% in the test. Most of the early failures occurred within the first 5 weeks of healing. Conclusions: Implants placed in a pre-contaminated site present higher early loss than those placed in a non-contaminated site. This study represents a valid and robust preclinical model to study mechanisms and reduction of early implant loss as new technologies become available. Clinical relevance: Scientific rationale for the study: There is lack of animal models to study early implant loss. Thus, a proposal of a new model is presented. With the validation of this model, new technologies can be implemented to prevent early implant loss

Aim: To compare clinical and histological keratinized tissue formation around teeth and implants following coronal repositioning of alveolar mucosa with or without a connective tissue graft (CTG).Materials and Methods: In nine beagle dogs, the third and fourth premolars (P3 and P4) were extracted from one side of the maxilla. Three months after the tooth extraction, a full-thickness buccal flap was raised and two implants were placed in those healed areas. On the contra-lateral side, a buccal flap was also raised at the P3 and P4 areas. Before suturing, the dogs were randomly assigned to three study groups (control, non-keratinized tissue [NKT], and non-keratinized tissue CTG [NKT-CTG]). In the control group, the buccal flaps were re-positioned around the teeth (P3 and P4) on one side, and implants on the other side, presenting an adequate band of keratinized tissue (KT). For the NKT and NKT-CTG groups, this buccal KT was then excised. In the NKT group, the buccal flap without KT (alveolar mucosa) was re-positioned around the teeth and implants. In the NKT-CTG group, a CTG taken from the excised KT was sutured to the buccal alveolar mucosa and then both were re-positioned around the teeth and implants. The clinical height of the KT was measured at baseline and at 1, 2, and 3 months of healing. The animals were sacrificed at 3 months, at which point the KT height was measured histologically. Results: The control group presented normal healing with a band of KT surrounding the teeth and implants. In the NKT and NKT-CTG groups, a new KT band approximately 2 mm in height (measured clinically and histologically) spontaneously formed around all teeth, regardless of whether a CTG had been placed. In the NKT implant group, no new KT was observed (clinically or histologically). Around the implants in the NKT-CTG group, a small amount of KT was formed in just two of the six implants.Conclusions: After surgical excision of KT, spontaneous KT is formed around teeth but not arou

Aim: To study clinical, radiographic, and microbiological outcomes after non-surgical therapy of peri-implantitis with or without adjunctive systemic metronidazole. Materials and Methods: A randomized placebo-controlled clinical trial was carried out in 32 subjects (62 implants) diagnosed with peri-implantitis. Implants received a mechanical non-surgical debridement session and systemic metronidazole or placebo. Clinical, radiographic, and microbiological outcomes were evaluated at baseline, 3, 6, and 12 months. Results: After 12 months, the test treatment resulted in significantly greater PPD reduction (2.53 vs. 1.02 mm) and CAL gain (2.14 vs. 0.53 mm) (p value <.05) in comparison with placebo. The test treatment also resulted in additional radiographic bone gain (2.33 vs. 1.13 mm) compared with placebo (p value <.05). There was a significantly greater decrease in Porphyromonas gingivalis, Tannerella forsythia, and Campylobacter rectus counts compared with the control group (p value <.05). At the end of follow-up, 56.3% of patients met the success criteria in the test group and 25% in the control group. Conclusions: The use of systemic metronidazole as an adjunct to non-surgical treatment of peri-implantitis resulted in significant additional improvements in clinical, radiographic, and microbiological parameters after 12 months of follow-up. This study is registered in ClinicalTrials.gov (NCT03564301)