Peri-Implant Behavior of Tissue Level Dental Implants with a Convergent Neck.

INTRODUCTION: The aim of this retrospective study was to analyze the radiographic peri-implant bone loss of bone level implants and tissue level implants with a convergent neck in screw-retained single crowns and in screw-retained fixed partial prostheses, after two years of functional loading. MATERIALS AND METHODS: The sample was divided into two groups according to their type: Group I: supracrestal implants with convergent transmucosal neck; Group II: crestal implants. In each group we distinguish two subgroups according to the type of prosthetic restoration: single crowns and a three-piece fixed partial prosthesis on two implants. To quantify bone loss, parallelized periapical radiographs were analyzed at the time of implant placement and after two years of functional load. RESULTS: A total of 120 implants were placed in 53 patients. After statistical analysis it was observed that for each type of implant bone loss was 0.97 ± 0.91 mm for bone level and 0.31 ± 0.48 mm for tissue level. No significant differences were found regarding the type of prosthesis and the location (maxilla or mandible) of the implants. CONCLUSIONS: Tissue level implants with a convergent transepithelial neck exhibit less peri-implant bone loss than bone level implants regardless of the type of prosthesis.

Periodontal Behavior Around Teeth Prepared with Finishing Line for Restoration with Fixed Prostheses. A Systematic Review and Meta-Analysis.

BACKGROUND: The objective of this systematic review and meta-analysis was to analyze the periodontal behavior around teeth prepared with horizontal finishing crowns supporting fixed metal-ceramic and zirconia full coverage crowns and fixed partial dentures (FDPs). MATERIALS AND METHODS: An electronic search was conducted to locate relevant clinical trials in four databases: PubMed, Embase, Cochrane, and Scopus. A manual search was made in the reference sections of the articles identified for any additional articles. No restrictions were applied regarding year of publication or language. The following variables were considered in quantitative and qualitative analysis: probing pocket depth (PPD); probing attachment level (PAL); plaque control record (PCR); bleeding on probing (BOP); and gingival margin migration. RESULTS: Twenty articles were selected for qualitative synthesis, and of these, nine underwent meta-analysis. Higher PCR was found in control teeth, while BOP, PPD, and PAL were higher around teeth prepared with horizontal finishing lines supporting complete coverage crowns/FDPs Gingival migration results were the clearest manifestation of compromised periodontal health around teeth prepared with horizontal finishing lines. CONCLUSIONS: Meta-analysis revealed that teeth prepared with horizontal finishing lines supporting crowns and FDPs present more periodontal disorders than untreated control teeth.

Influence of Implant-Prosthetic Connection on Peri-Implant Bone Loss: A Prospective Clinical Trial with 2-Year Follow-up.

PURPOSE: To analyze peri-implant bone loss around six different types of implant-prosthetic connections over a 2-year follow-up period. MATERIALS AND METHODS: A total of 120 implants were divided into six groups (n = 20), three with crestally and three with supracrestally placed implants, with different internal connections, placed in posterior sectors (molar and premolar), and bearing one-piece CAD/CAM restorations screwed directly to each implant's prosthetic platform. Bone height was measured from parallelized periapical radiographs taken at the moment of loading and 2 years later. RESULTS: The patient sample included 61 subjects, 36 men and 25 women. Significant differences were found in bone loss between groups, the implant with internal hex and convergent transmucosal collar showing the least bone loss (P < .001) in comparison with the other designs. Supracrestally placed implants underwent less bone loss than crestally placed implants (P = .025). CONCLUSION: Peri-implant bone loss is influenced by the level of implant placement in relation to the bone crest (crestal or supracrestal) and by the morphology of the prosthetic platform.

Are Metal-Free Monolithic Crowns the Present of Prosthesis? Study of Mechanical Behaviour.

PURPOSE: To analyze in vitro the mechanical behavior of five types of complete coverage crowns fabricated from different materials. MATERIALS AND METHODS: Seventy-five full coverage crowns were divided into five groups according to material: Group I, metal core with feldspathic ceramic covering (MC- control group); Group II, zirconia core with feldspathic ceramic covering (CZ); Group III, tetragonal monolithic zirconia (TMZ); Group IV, cubic monolithic zirconia (CMZ); Group V, high molecular weight polymethyl methacrylate (PMMAG) doped with graphene nanoparticles. All crowns underwent in vitro fatiguing by dynamic loading in wet conditions to simulate the masticatory forces to which prosthodontic materials are subject in the oral medium. Lastly, fracture resistance was evaluated by static compression testing. RESULTS: The fracture resistance values obtained were as follows: Group MC, 2443.6 ± 238.6 N; Group CZ, 2095.4 ± 329.2 N; Group TMZ, 2494.6 ± 236.6 N; Group CMZ, 1523.6 ± 325.2 N; and Group PMMAG, 1708.9 ± 386.6 N. Group MC presented higher strength with statistically significant differences in comparison with Groups CZ (P = 0.002), CMZ (P < 0.001), and PMMAG (P < 0.001). Weibull distribution showed less probability of cumulative biomechanical failure in Groups MC and TMZ. CONCLUSIONS: Metal-ceramic and tetragonal zirconia showed high fracture resistance, while cubic zirconia and PMMA doped with graphene nanoparticles obtained lower values.