José de Albuquerque Calasans-Maia

Early osseointegration driven by the surface chemistry and wettability of dental implants

Objective The objective of this study was to investigate the impact of two different commercially available dental implants on osseointegration. The surfaces were sandblasting and acid etching (Group 1) and sandblasting and acid etching, then maintained in an isotonic solution of 0.9% sodium chloride (Group 2). Material and Methods X-ray photoelectron spectroscopy (XPS) was employed for surface chemistry analysis. Surface morphology and topography was investigated by scanning electron microscopy (SEM) and confocal microscopy (CM), respectively. Contact angle analysis (CAA) was employed for wetting evaluation. Bone-implant-contact (BIC) and bone area fraction occupied (BAFO) analysis were performed on thin sections (30 μm) 14 and 28 days after the installation of 10 implants from each group (n=20) in rabbits’ tibias. Statistical analysis was performed by ANOVA at the 95% level of significance considering implantation time and implant surface as independent variables. Results Group 2 showed 3-fold less carbon on the surface and a markedly enhanced hydrophilicity compared to Group 1 but a similar surface roughness (p>0.05). BIC and BAFO levels in Group 2 at 14 days were similar to those in Group 1 at 28 days. After 28 days of installation, BIC and BAFO measurements of Group 2 were approximately 1.5-fold greater than in Group 1 (p<0.05). Conclusion The surface chemistry and wettability implants of Group 2 accelerate osseointegration and increase the area of the bone-to-implant interface when compared to those of Group 1.

A randomized controlled clinical trial to evaluate a new xenograft for alveolar socket preservation

OBJECTIVE The aim of this clinical trial was to compare the effect of Bio-Oss(®) and a new bovine xenograft (Osseus(®) ) in alveolar sockets after a 24-week healing period. MATERIALS AND METHODS A total of 20 adult volunteers ages 30-60 were subjected to single tooth extraction. A tooth extraction was performed at the baseline. All sites were randomly allocated to two test groups (TG1: grafted using a new bovine xenograft, Osseus(®) , and TG2: grafted using commercially available bovine xenograft-Bio-Oss(®) ). Six months later, a sample of the grafted area was obtained and implants were inserted in the same site. Histological sections were examined focusing on the presence of fibrous connective tissue (CT), and newly formed bone in direct contact with the graft. The HE-stained sections were subjected to histomorphometrical evaluation using Image Pro-Plus(®) software (Release 7.0). The definitive crown was placed 3 months later. RESULTS Upon completion of the study, no patients were removed from the study and all inserted implants (10 in each group) were eventually integrated. After 6 months, in the TG1, the mean value of new bone formation was 33.7 (± 7.1), for CT was 32.3 (± 8.9) and for the remaining biomaterial was 10.7 (± 16.2). In the TG2, the mean value of new bone formation was 19.3 (± 22.6), of the CT was 49.9 (± 14.1) and of the remaining biomaterial was 22.6 (± 7.9). CONCLUSIONS No statistically significant difference was observed between TG1 and TG2 after 6 months (P > 0.05), and both biomaterials afforded a more favorable implant position.

Short-term in vivo evaluation of zinc-containing calcium phosphate using a normalized procedure

The effect of zinc-substituted calcium phosphate (CaP) on bone osteogenesis was evaluated using an in vivo normalized ISO 10993-6 protocol. Zinc-containing hydroxyapatite (ZnHA) powder with 0.3% by wt zinc (experimental group) and stoichiometric hydroxyapatite (control group) were shaped into cylindrical implants (2×6 mm) and were sintered at 1000 °C. Thermal treatment transformed the ZnHA cylinder into a biphasic implant that was composed of Zn-substituted HA and Zn-substituted β-tricalcium phosphate (ZnHA/βZnTCP); the hydroxyapatite cylinder was a highly crystalline and poorly soluble HA implant. In vivo tests were performed in New Zealand White rabbits by implanting two cylinders of ZnHA/βZnTCP in the left tibia and two cylinders of HA in the right tibia for 7, 14 and 28 days. Incorporation of 0.3% by wt zinc into CaP increased the rate of Zn release to the biological medium. Microfluorescence analyses (μXRF-SR) using synchrotron radiation suggested that some of the Zn released from the biomaterial was incorporated into new bone near the implanted region. In contrast with previous studies, histomorphometric analysis did not show significant differences between the newly formed bone around ZnHA/βZnTCP and HA due to the dissolution profile of Zn-doped CaP. Despite the great potential of Zn-containing CaP matrices for future use in bone regeneration, additional in vivo studies must be conducted to explain the mobility of zinc at the CaP surface and its interactions with a biological medium.

Increased overjet is a risk factor for dental trauma in preschool children.

CONTEXT Traumatic dental injury and malocclusion constitute a public health problem due to their high prevalence. Preventing or detecting such conditions, in any population, is of paramount importance. AIM Assessing the association of anterior occlusal characteristics and dental trauma in preschool children. SETTINGS AND DESIGN A cross-sectional study was carried out with 2-6-year-old randomly selected by a sample calculation, resulting in 606 subjects MATERIALS AND METHODS A questionnaire to collect information about the sample (age, gender, and race) was sent to the childrens parents. Two trained and calibrated examiners (Kappa 0.80) evaluated dental trauma according to criteria established by the World Health Organization. The following anterior occlusal characteristics were evaluated: Normal occlusion, anterior open bite, anterior crossbite, increased overjet (categorized as ≥3 mm), and increased overbite (categorized as ≥3 mm). STATISTICAL ANALYSIS USED The variables associations were assessed (odds ratio, Chi-square test, and logistic regression, P < 0.05) using statistical software (SPSS, version 16.0). RESULTS Dental trauma was observed in 20.8% and malocclusion in 48.6% of the children. There is an association between malocclusion and dental trauma (P = 0.01). Children with malocclusion have a 64% higher chance of suffering dental trauma. Increased overjet was the type of malocclusion related to a higher rate of tooth fracture (P < 0.01). Subjects with this type of malocclusion suffered tooth fractures three times more often than subjects with other malocclusion types. CONCLUSIONS There was association of dental trauma and malocclusion. Increased overjet was the most common malocclusion related to dental trauma. Preventive strategies are needed to reduce the rate of anterior malocclusion and, consequently, dental trauma in preschool children.

Osseoinduction Evaluation of Hydroxyapatite and Zinc Containing Hydroxyapatite Granules in Rabbits

This study investigated the osteoinductive potential of granules of stoichiometric hydroxyapatite (HA) and 0.5% zinc containing hydroxyapatite (ZnHA) in intramuscular (IM) site of rabbit’s abdomen. The biomaterials were both used in granular form, with 75% porosity and particle diameter between 450 and 500μm, sintered at 1100°C. Both materials performed adequately on a multiparametric in vitro cytocompatibility assay, indicating their suitability for in vivo testing. After approval by the Ethics Commission on Teaching and Research in Animals, fifteen rabbits were submitted to general anesthesia, incision and tissue dilatation, and a small site was created for HA (right incision) and ZnHA (left incision) intramuscular implantation. The animals were killed after 2, 4 and 12 weeks for biomaterials and surrounding tissues removal. Histological analysis after 2 weeks revealed the presence of granulation tissue surrounding biomaterials with multinucleated giant cells and no newly formed bone for both materials. After 4 weeks there was fibrous tissue involving the material and few inflammatory cells. Following 12 weeks it was observed the presence of connective tissue surrounding the biomaterial, cellularized enough for the two experimental groups, but it was not observed the presence of bone matrix associated with the biomaterials. We conclude that both biomaterials are cytocompatible and did not present the property of osseoinduction after 12 weeks of implantation.

Alveolar bone repair with strontium- containing nanostructured carbonated hydroxyapatite

ABSTRACT Objective This study aimed to evaluate bone repair in rat dental sockets after implanting nanostructured carbonated hydroxyapatite/sodium alginate (CHA) and nanostructured carbonated hydroxyapatite/sodium alginate containing 5% strontium microspheres (SrCHA) as bone substitute materials. Methods Twenty male Wistar rats were randomly divided into two experimental groups: CHA and SrCHA (n=5/period/group). After one and 6 weeks of extraction of the right maxillary central incisor and biomaterial implantation, 5 μm bone blocks were obtained for histomorphometric evaluation. The parameters evaluated were remaining biomaterial, loose connective tissue and newly formed bone in a standard area. Statistical analysis was performed by Mann-Withney and and Wilcoxon tests at 95% level of significance. Results The histomorphometric results showed that the microspheres showed similar fragmentation and bio-absorbation (p>0.05). We observed the formation of new bones in both groups during the same experimental periods; however, the new bone formation differed significantly between the weeks 1 and 6 (p=0.0039) in both groups. Conclusion The CHA and SrCHA biomaterials were biocompatible, osteoconductive and bioabsorbable, indicating their great potential for clinical use as bone substitutes.

Effect of Carbonate-Apatite on Bone Repair in Non-Critical Size Defect of Rat Calvaria

The objective of this study was to investigate the bone repair of carbonate apatite (cHA) in comparison to hydroxyapatite (HA, control group), on osseous repair of non-critical size defect in rat calvaria. Spheres (400500μm) of both materials were synthesized under 37°C (cHA) and 90°C (HA) and were not sintered. Fifteen rats Wistar were submitted to general anesthesia and two perforations (4mm each) were made, one in each parietal bone, for implantation of cHA (left side) and HA spheres (right side). After 1, 3 and 6 weeks, five animals of each group were killed and the two fragments with the biomaterial were collected from the calvaria. The bone blocks with biomaterial were demineralized and 5μm thick semi-serial sections were done for histological analysis. The experimental group of 6 weeks did not show the presence of spheres of both biomaterials and few spheres were observed after 1 and 3 weeks. Histological analysis showed the connective tissue repairing the surgical defect after 1 week and newly formed bone after 3 weeks of surgery. Thus, we concluded both materials are biocompatible, promote osteoconduction and in all studied periods the biomaterials showed to be resorbable.

The ability of topical and systemic statins to increase osteogenesis around dental implants: a systematic review of histomorphometric outcomes in animal studies

The purpose of this systematic review was to evaluate the quantitative histomorphometric outcomes of animal studies investigating statins as a pro-osteogenic agent to enhance the osseointegration of dental implants. Some animal studies have suggested a beneficial action of statins on bone tissue. Electronic and manual literature searches, without date or language restriction, ​​were performed by two independent review authors up to February 2017. Eligibility criteria included animal trials quantitatively analysing the pro-osteogenic effect of statins on dental implants. The quality of the included studies was assessed using the ARRIVE guidelines. The search and selection process yielded 12 studies, published between 2004 and 2015. The experimental animals models used were rats and dogs. The statins used in the studies were simvastatin and fluvastatin, which were administered locally or systemically, or applied to the implant surface. All of the selected studies showed a statistically significant positive effect of statins on bone formation around implants. The mean quality assessment score (ARRIVE) of the studies was 11.5±2.27 out of a possible total of 25 points. The histomorphometric data from available preclinical studies suggest a positive effect of statins on increasing osteogenesis around dental implants.

Accelerated Healing Period with Hydrophilic Implant Placed in Sheep Tibia

The objective of this study was to evaluate the early osseointegration of two different implants surfaces, a sandblasted and acid-etched surface (TN) compared with same geometry and surface roughness modified to be hydrophilic/wettable by conditioning in an isotonic solution of 0.9% sodium-chloride (TA) through histological and histomorphometric analysis after sheep tibia implantation. Forty dental implants, divided in two groups (TN and TA) were placed in the left tibia of twenty healthy, skeletally mature Santa Ines sheep (n=5/experimental period). After 7, 14, 21 and 28 days post-implantation, the samples were removed and the sheep were kept alive. Analysis of resin sections (30 μm) allowed the quantification of bone area (BA) and bone-to-implant contact (BIC). TA group presented nearly 50% increase in BA at 14 days (p<0.001, ANOVA - Tukeys post test) compared with 7 days. The TA presented higher values than the TN for BA and BIC at 14, 21, and 28 days after placement, stabilizing bone healing. TA hydrophilic surface promoted early osseointegration at 14 and 21 days compared to TN, accelerating bone healing period post-implant placement in sheep tibia.