Carlos Eduardo Francischone

The present study evaluated the effect of the taper angle of different internal conical connection implants and cyclic loading on the implant-abutment bacterial seal. A total of 96 implant-abutment sets were divided into eight groups. Four groups of different taper degrees with cyclic mechanical loading of 500,000 cycles per sample, with a 120-N load at 2 Hz before analysis [16DC (16-degree, cycled), 11.5DC (11.5-degree, cycled), 3DC (3- degree, cycled) and 4DC (4- degree, cycled)] were compared to four control groups without cyclic loading [16D (16-degree), 11.5D (11.5-degree), 3D (3-degree), and 4D (4-degree)]. Microbiological analysis was performed by immersing all samples in a suspension containing Escherichia coli and incubating them at 37°C. After 14 days, the presence of bacterial seals was evaluated. Fisher-Freeman-Halton exact tests and binomial tests were performed (5% significance level). The groups showed significant differences in bacterial seal, and mechanical load cycling improved the bacterial seal in the 3DC group. In all other groups, no significant differences in bacterial seal were found between cycled and uncycled samples. To conclude, the internal conical connection with a 3-degree taper angle showed better results than the other connection with different angles when subjected to load cycling. However, none of the angles tested were fully effective in sealing the implant-abutment interface.

Introduction. Considering oral rehabilitation with dental implants, many studies have aimed at improving bone regeneration through the use of biomaterials. Objective. This study aimed at comparing bone neoformation in patients undergoing bilateral maxillary sinus surgery with two bovine biomaterials. Materials and Methods. This is a randomized, blinded, clinical crossover, and divided mouth study. Ten participants with an indication of maxillary sinus enlargement were selected and underwent surgical treatment with Bio-Oss® graft biomaterial (graft 1) on one side and Lumina-Porous® graft biomaterial (graft 2) on the other. The samples were collected after nine months and fixed and then decalcified in 10% ethylenediamine tetra-acetic acid (EDTA) solution for 30 days to process and make histological slides. Connective and bone tissue were further analyzed to identify the amount of newly formed bone. Results. The graft 1 group had a greater formation of vital mineralized tissue when compared to the graft 2 group ( p = 0.01). For nonvital mineralized tissue and amount of connective tissue, there was no statistical difference ( p = 0.21 and p = 0.09, respectively). The medullary spaces were larger in the graft 2 group. The group treated with graft 1 presented a higher percentage of osteoclasts and viable osteocytes compared to the graft 2 group ( p = 0.014 and p = 0.027, respectively). Conclusion. Every day, new alternative biomaterials are offered as an option in oral rehabilitation. In this study, both treatments induced bone neoformation after 9 months; however, the group treated with Bio-Oss® showed a higher percentage of vital mineralized bone tissue.

Objectives: This study aimed to evaluate vestibular gingival thickness in unitary implants located in the anterior maxilla through a cone beam tomography. Material and methods: After visual classification of the gingival biotype of the 32 patients selected for this study (16 patients with thin biotype and 16 patients with thick biotype) measurements of the vestibular tissue thickness were made at 2, 4 and 6 mm from the gingival margin in the apical direction in the most longitudinal transverse cut of the implant and the contralateral tooth through tomographic cone beam examination for soft tissue. The data of age and gender of the patients, mean buccal wall thickness of the implants and contralateral natural teeth, and the use of connective tissue graft (CTG) were tabulated for descriptive analysis. Results: For thin gingival biotype, mean vestibular gingival thickness varied between 1.26 ± 0.31 mm (teeth) and 2.65 ± 0.93 mm (implant), and for thick biotype varied from 1.77 ± 0.58 mm (teeth) and 3.01 ± 0.96 mm (implant). The use of CTG increased the buccal thickness of thick biotype when compared to thin biotype without CTG. Conclusions: It was not possible to establish a direct relationship between the classification of the gingival biotype of the contralateral teeth and the gingival biotype of the implants installed in the anterior region of the maxilla, but CTG was shown to be efficient in increasing gingival tissue thickness.

Objective: Evaluate the biomechanical behavior of the influence of different internal angles of conical prosthetic connections in fixed partial prostheses of three elements, through the tridimensional finite element method. Methods: Two different models of segment of the posterior portion of the mandible, with two implants with conical connections at angulations of 11.5 and 16 degrees. Afterwards, and occlusal load of 180N was used, and divided into 2 points of application on the premolar, and 400N divided into 5 points of application on the molar. Data were acquired as the tensile, compressive and shear stresses on cortical and medullary bone, and von Mises stresses on implants and prosthetic components of two implants in both in three-unit fixed partial prosthesis. In the quantitative analysis, both in cortical and medullary bone, the tension peaks in tensile, compression, and shear forces were higher for the CM16 group. Results: When analyzing qualitatively, the cortical and medullary bones presented a greater stress around the implant platform with a higher incidence in the implant in the molar region. In the von Misses analysis in both groups, the tensions were concentrated in the cervical region of the implants, in the first threads, in the premolar and molar regions. Regarding prosthetic pillars, the stress concentration was located in the region of contact with the implant. Conclusion: The increased angulation of conicity of the internal conical connections represents a determinant factor to increase in stress concentration in the implants, prosthetic components and adjacent structures, such as the cortical and medullary bone.

The aim of this study was to clinically and radiographically compare extra short and standards implants. Forty-two implants were installed in 10 selected patients. They received prosthetic loading only after the conventional waiting time for osseointegration and the prostheses were made ferulized. Radiographic shots were performed to evaluate vertical and horizontal bone losses at times T1 (prosthetic installation), T2 (6 months follow-up) and T3 (12 months follow-up). Biological parameters such as bone level around the implants (CBL) were evaluated, CBL alteration (CBLC), total crown length (TCL) and implant/crown ratio (ICR) were digitally calculated. All implants included in the study were submitted to the analysis of the implant stability quotient (ISQ) at the time of implant installation (T0) and at 12 months of prosthetic function (T3). Data were statistically tested. The ICR was higher in the test group than in the control group (p0.05). No correlation was found between CBLC and ICR parameters, as well as between ISQ and implant length. We may conclude that standards and extra short implants can provide similar clinical results in prosthetic rehabilitation of the atrophic jaw over 12 months of follow-up.