The passivation of titanium dental implants is performed in order to clean the surface and obtain a thin layer of protective oxide (TiO₂) on the surface of the material in order to improve its behavior against corrosion and prevent the release of ions into the physiological environment. The most common chemical agent for the passivation process is hydrochloric acid (HCl), and in this work we intend to determine the capacity of citric acid as a passivating and bactericidal agent. Discs of commercially pure titanium (c.p.Ti) grade 4 were used with different treatments: control (Ctr), passivated by HCl, passivated by citric acid at 20% at different immersion times (20, 30, and 40 min) and a higher concentration of citric acid (40%) for 20 min. Physical-chemical characterization of all of the treated surfaces has been carried out by scanning electronic microscopy (SEM), confocal microscopy, and the ‘Sessile Drop’ technique in order to obtain information about different parameters (topography, elemental composition, roughness, wettability, and surface energy) that are relevant to understand the biological response of the material. In order to evaluate the corrosion behavior of the different treatments under physiological conditions, open circuit potential and potentiodynamic tests have been carried out. Additionally, ion release tests were realized by means of ICP-MS. The antibacterial behavior has been evaluated by performing bacterial adhesion tests, in which two strains have been used: Pseudomonas aeruginosa (Gram–) and Streptococcus sanguinis (Gram+). After the adhesion test, a bacterial viability study has been carried out (‘Life and Death’) and the number of colony-forming units has been calculated with SEM images. The results obtained show that the passivation with citric acid improves the hydrophilic character, corrosion resistance, and presents a bactericide character in comparison with the HCl treatment. The increasing of citric acid concentration improves the bactericide effect but decreases the corrosion resistance parameters. Ion release levels at high citric acid concentrations increase very significantly. The effect of the immersion times studied do not present an effect on the properties.

Objectives: The main objective of the study was to compare the dimensional ridge changes and the histological composition after the use of an allograft or xenograft and a resorbable membrane in ridge preservation in molar sites and to evaluate the influence of bone plate thickness on dimensional changes and the need of lateral sinus augmentation following ridge preservation.Materials and methods: Twenty‐four patients in need of maxillary or mandibular first or second molar extraction and subsequent implant placement were included and randomly assigned to a group; allograft or xenograft, plus a collagen membrane. Cone‐beam computed tomographies were obtained after molar extraction and after 5 months. A bone sample was harvested at the time of implant placement and analyzed by histomorphometry.Results: Bone ridge was reduced significantly. Major changes in width occurred at 1 mm from the bone crest (−2.93 ± 2.28 mm) (p = .0002), while in height, the greatest reduction occurred at the buccal area (−1.97 ± 2.21 mm) (p = .0006). However, differences between groups were not significant. Thicker buccal bone plates exhibited less bone remodeling, while histologically, both biomaterials resulted in similar tissue composition. The resulting available bone height in the implant site measured 7.30 ± 3.53 mm initially and 6.8 ± 3.61 mm after 5 months which allowed implant placement without the need for lateral sinus augmentation in all cases. Still, 55% of the preserved areas needed transcrestal sinus lift.Conclusion: Ridge preservation in molar sites using a mineralized allograft or xenograft provides similar dimensional and histomorphometrical results after 5 months.

Background: The objective of this trial was to investigate the clinical and radiographic significance of using a mixture of mineralized and demineralized allografts in combination (M) or not (NM) with a resorbable cross‐linked barrier membrane in the reconstructive therapy of peri‐implantitis defects.Methods: A two‐arm randomized clinical trial was performed in patients diagnosed with peri‐implantitis that exhibited contained defects. Clinical parameters were recorded at baseline (T₀), 6 months (T₁), and 12 months (T₂). Radiographic parameters were recorded at T₀ and T₂. A composite criterion for disease resolution was defined a priori. A generalized linear model of repeated measures with generalized estimation equation statistical methods was used.Results: Overall, 33 patients (n_implants = 48) completed the study. At T₂, mean disease resolution was 77.1%. The use of a barrier membrane did not enhance the probability of disease resolution at T₂ (odds ratio [OR] = 1.55, p = 0.737). Conversely, the odds of disease resolution were statistically associated with the modified plaque index recorded at T₀ (OR = 0.13, p = 0.006) and keratinized mucosa width (OR = 2.10, p = 0.035). Moreover, women exhibited greater odds to show disease resolution (OR = 5.56, p = 0.02).Conclusion: Reconstructive therapy by means of a mixture of mineralized and demineralized allografts is effective in clinically resolving peri‐implantitis and in gaining radiographic marginal bone level. The addition of a barrier membrane to reconstructive therapy of peri‐implantitis does not seem to enhance the outcomes of contained bone defects (NCT05282667).