Correction to: Metallic ion content and damage to the DNA in oral mucosa cells of children with fixed orthodontic appliances.

Due to an unfortunate turn of events, the surname of the fourth author appeared incorrectly in the original publication and should have read Calvo Guirado.

The influence of three different apical implant designs at stability and osseointegration process: experimental study in rabbits.

OBJECTIVES: The aim of this study was to perform a histomorphometric and biomechanical comparison of three implants with different designs of the apical area to promote a better bone initial stability and its correlation with the osseointegration. MATERIAL AND METHODS: Fifty-four tapered implants with same length, diameter and surface properties but with three different apical configurations (Group I: MK4: Group II: C1 and Group III: MK7) were inserted in the tibia of rabbits. Implant stability and bone formation were evaluated by resonance frequency analysis measured at 0, 6, 8 and 12 weeks and by histomorphometric analysis performed at 6, 8 and 12 weeks. RESULTS: Statistical test to compare the stability through the implant stability quotient in the four times showed few differences between the groups and time periods proposed, with significance set at P < 0.05. In the bone-implant contact, by comparing the groups in the three times proposed, it was possible concluded that there is a similar behavior among the three implant design (P < 0.05). CONCLUSION: With the limitations of this animal study, it can be concluded that the design of the apical area influences the implant stability and the bone-to-implant contact.

Topical applications of vitamin D on implant surface for bone-to-implant contact enhance: a pilot study in dogs part II.

OBJECTIVE: The aim of this study was to evaluate the effect of topical application of vitamin D over implant surface, placed immediately to the extraction, throughout histological and histomorphometric analysis of peri-implant tissue. MATERIAL AND METHODS: Six American foxhound dogs were used in the study. Mandibular premolar distal roots were extracted. Twenty-four immediate conical C1 implants (MIS, Barlev, Israel) were randomly assigned to the distal site on each site of the mandible in three groups: (Group CI) 12 titanium implants alone; (Test Group DI) 12 titanium implants supplemented with vitamin D. Prior to implanting, test implants (DI) were submerged in vitamin D 10% solution. No treatment was applied at control implants (CI). After 12 weeks, animals were sacrificed. Block sections were obtained and processed for mineralized ground sectioning. Bone-to-implant contact (Total BIC and BIC%), new bone formation (NBF), interthread bone (ITB), and histological linear measurements (HLM) were analyzed. RESULTS: At 12 weeks, all implants were clinically stable and histologically osseointegrated. BIC evaluation showed Total BIC mean and SD values for DI (48.96 ± 2.14), CI (44.56 ± 1.75) (P < 0.05), BIC% DI (43.59 ± 0.98), and CI (42.67 ± 9.26) (P > 0.05). For interthread bone formation, values were as follows: DI (15.21 ± 3.87), CI (14.79 ± 1.45) (P > 0.05), no statistically differences. Regarding peri-implant new bone formation, no statistically differences could be found between the two groups DI (31.87 ± 1.23), CI (27.18 ± 2.38) (P > 0.05). For linear measurements, test group (DI) showed statistically significant less buccal crestal bone loss (CBL) DI (0.37 ± 0.12)*, CI (1.26 ± 0.8) (P < 0.05), and vitamin D implants showed less lingual junctional epithelium DI (1.58 ± 0.43)*, CI (2.18 ± 0.48) (P < 0.05). No differences were observed in the buccal mucosa. CONCLUSION: With the limitation of animal studies, topical application of vitamin D on dental implants could reduce crestal bone loss and increase 10% more bone-to-implant contact at 12-week follow-up period.

The effects of healing abutments of different size and anatomic shape placed immediately in extraction sockets on peri-implant hard and soft tissues. A pilot study in foxhound dogs.

OBJECTIVES: The aim of this animal study was to compare the effects of narrow, concave-straight and wide anatomic healing abutments on changes to soft tissues and crestal bone levels around implants immediately placed into extraction sockets in foxhound dogs. MATERIALS AND METHODS: Forty-eight titanium implants (Bredent Medical GMBH, Germany) of the same dimensions were placed in six foxhound dogs. They were divided into two groups (n = 24): test (implants with anatomic abutment) and control (implants with concave-straight abutment). The implants were inserted randomly in the post extraction sockets of P2 , P3 , P4, and M1 bilaterally in six dogs. After eight and twelve weeks, the animals were sacrificed and samples extracted containing the implants and the surrounding soft and hard tissues. Soft tissue and crestal bone loss (CBL) were evaluated by histology and histomorphometry. RESULTS: All implants were clinically and histologically osseointegrated. Healing patterns were examined microscopically at eight and twelve weeks. After eight and twelve weeks, for hard tissues, the distance from the implant shoulder to the first bone-to-implant contact (IS-C) was higher for control group in the lingual aspect with statistical significance (P < 0.05). For soft tissues (STL), the distance from the top of the peri-implant mucosa to the apical portion of the junction epithelium (PM-Je) was significantly less on the lingual aspect in the test group (with wider abutment) at eight and twelve weeks (P < 0.05). The distance from the top of the apical portion of the junction epithelium to the first bone-to-implant contact (Je-C) was significantly higher in the test group (wider abutment) in the lingual aspect at eight and twelve weeks (P < 0.05). There was no connective tissue contact with any abutment surface. CONCLUSIONS: Within the limitations of this animal study, anatomic healing abutments protect soft and hard tissues and reduce crestal bone resorption compared with concave-straight healing abutments.

Volumetric analysis of remodelling pattern after ridge preservation comparing use of two types of xenografts. A multicentre randomized clinical trial.

OBJECTIVES: The aim of this randomized clinical trial was to analyse and compare the volumetric changes after ridge preservation procedures using two different biomaterials and to evaluate associations between outcome variables and pristine three-dimensional aspects of the ridges. MATERIALS AND METHODS: Twenty-eight patients subjected to single-tooth alveolar ridge preservation were enrolled in the present multicentre, single-blind, prospective and randomized clinical trial. Fourteen sites were randomly allocated to each experimental group. The experimental sites were grafted with pre-hydrated collagenated cortico-cancellous porcine bone (coll group) or with a cortical porcine bone (cort group) and a collagen membrane; a secondary soft tissue healing was obtained for all experimental sites. Plaster casts were scanned (preoperative, at 1 and 3 months postoperative). Analysis of volumes and areas was performed, and all measured variables were statistically compared. RESULTS: Intragroup analyses at 3 months revealed that when examining changes related to three-dimensional features of remodelling patterns (volume, surfaces, height and shape), the two biomaterials showed similar behaviours with a minor loss in volume and ridge surface. Intergroup analysis at 3-month survey revealed that volume resorption of the coll group (244 mm3 ) was significantly lower (P = 0.0140) than that of the cort group (349 mm3 ). The reduction for basal surface appeared significantly different between the two groups at 1-month survey only (P = 0.0137), while the final basal surface reduction was 4.9 and 12.2 mm2 for coll and cort group, respectively. The superior surface reduction was 40.8 mm2 for coll and 50.7 mm2 for cort group, with no significant difference between the two groups. CONCLUSION: At the 3rd month analysis, coll group showed a significantly lower reduction of ridge volume and a significantly smaller shrinkage of the basal area when compared to the cort group; moreover, the coll group experienced a smaller superior surface shrinkage when compared to the cort group, even though no significance was evaluated.

Bone neoformation of a novel porous resorbable Si-Ca-P-based ceramic with osteoconductive properties: physical and mechanical characterization, histological and histomorphometric study.

OBJECTIVE: The aims of the present work were to study a new porous Nurse's A ceramic (Si-Ca-P-based material) bone substitute and examine its mechanical properties in vitro and the biocompatibility, osteoconductivity and resorption process in vivo. MATERIALS AND METHOD: Porous ceramic scaffolds were prepared by solid-state reaction and implanted in critical-sized defect created in 15 NZ rabbits. Strength values were determined by the diametrical compression of disk test. Weibull analyses were performed following the European Standard for technical ceramics EN-843-5: 1996, considering 90% of confidence intervals. Results were correlated with scanning microscope observations of fracture surfaces. Implanted scaffolds were characterized by histological and histomorphometric point of view. RESULTS: The parameters of the Weibull distribution of strength, determined by diametrical compression of disks, were modulus m = 13, and characteristic strength σ0  = 0.60 MPa (90% confidence limit: m = 7.2-17.6, σ0  = 0.570-0.578). Porous calcium silicophosphate scaffolds showed significantly more bone formation in the pores and in the periphery of the implant than the control group. Histomorphometric analysis revealed that the ceramic scaffold (62.23 ± 0.34*) produced higher values of bone-to-implant contact (BIC) percentages (higher quality, closer contact); moreover, defect closure was significative in relation with control group. CONCLUSIONS: The porous calcium silicophosphate ceramic is biocompatible, partially resorbable and osteoinductive material. This rabbit study provides radiological and histological evidences confirming the suitablity of this new material for bone tissue regeneration on critical defects.

Influence of hydroxyapatite granule size, porosity, and crystallinity on tissue reaction in vivo. Part A: synthesis, characterization of the materials, and SEM analysis.

OBJECTIVE: The aim of this study was the synthesis and analysis of the tissue reaction to three different Hydroxyapatite (HA)-based bone substitute materials differing only in granule size, porosity, and crystallinity through an animal experimental model at 60 days. MATERIALS AND METHODS: Three different HA-based biomaterials were synthesized and characterized by X-ray diffraction, SEM, and EDS analysis, the resultant product was ground in three particle sizes: Group I (2000-4000 µm), Group II (1000-2000 µm), and Group III (600-1000 µm). Critical size defects were created in both tibias of 15 rabbits. Four defects per rabbit for a total of 60 defects were grafted with the synthesized materials as follows: Group I (15 defects), Group II (15 defects), Group III (15 defects), and empty (15 defects control). After animals sacrifice at 60 days samples were obtained and processed for SEM and EDS evaluation of Ca/P ratios, elemental mapping was performed to determine the chemical degradation process and changes to medullary composition in all the four study groups. RESULTS: The tendency for the density was to increase with the increasing annealing temperature; in this way it was possible to observe that the sample that shows highest crystallinity and crystal size corresponding to that of group I. The SEM morphological examination showed that group III implant showed numerous resorption regions, group II implant presented an average resorption rate of all the implants. The group I displayed smoother surface features, in comparison with the other two implants. CONCLUSION: The data from this study show that changing the size, porosity, and crystallinity of one HA-based bone substitute material can influence the integration of the biomaterials within the implantation site and the new bone formation.

Marginal bone loss evaluation around immediate non-occlusal microthreaded implants placed in fresh extraction sockets in the maxilla: a 3-year study.

OBJECTIVE: To evaluate marginal bone loss over 3 years around immediate microthreaded implants placed in the maxillary anterior/esthetic zone and immediately restored with single crowns. MATERIAL AND METHODS: Seventy-one implants (with microthreads up to the platform--rough surface body and neck, internal connection and platform switching) were placed in fresh extraction sockets in the maxillary arches of 30 men and 23 women (mean age 37.85 ± 7.09 years, range 27-60). All subjects had at least 3 mm of soft tissue to allow the establishment of adequate biologic width and to reduce bone resorption. Each patient received a provisional restoration immediately after implant placement with slight occlusal contact. Mesial and distal bone height was evaluated using digital radiography on the day following implant placement (baseline) and after 1, 2, and 3 years. Primary stability was measured with resonance frequency analysis. RESULTS: No implants failed, resulting in a cumulative survival rate of 100% after 3 years. Marginal bone loss from implant collar to bone crest measured at baseline (peri-implant bone defect at the fresh extraction socket) and after 3 years was 0.86 mm ± 0.29 mm. Mesial and distal site crestal bone loss ranged from 3.42 mm ± 1.2 mm at baseline to 3.51 mm ± 1.5 mm after 3 years (P = 0.063) and from 3.38 mm ± 0.9 mm at baseline to 3.49 mm ± 0.9 mm after 3 years, respectively (P = 0.086). CONCLUSIONS: This prospective study found minimal marginal bone loss and a 100% implant survival rate over the 3-year follow-up for microthreaded immediate implants subjected to immediate non-occlusal loading.

Crestal bone reactions to immediate implants placed at different levels in relation to crestal bone. A pilot study in Foxhound dogs.

OBJECTIVES: The aim of the present study was to evaluate bone-to-implant contact (BIC) and bone remodeling dynamics after immediate implant placement at different levels in relation to the crestal bone. MATERIALS AND METHODS: The mandibular second, third, and fourth premolars of six Foxhound dogs were extracted bilaterally. Randomly, three implants were immediately placed in the hemi-arches of each dog, crestally or 2 mm subcrestally. Three dogs were allowed an 8-week submerged healing period, and the other three at 12-week submerged healing period. The animals were sacrificed at 12 weeks and samples were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out to compare BIC, bone neoformation, and bone remodeling. RESULTS: All implants osseointegrated clinically and histologically. Healing patterns examined microscopically at eight and twelve weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. The Total BIC mean value for the crestal group 44.52% at 8 weeks and 39.50% at 12 weeks, and for the subcrestal group was 47.33% at 8 weeks and 53.85% at 12 weeks%. There was less bone resorption in the subcrestal group (test) than in crestal group (control). CONCLUSIONS: Within the limitations of this study, our findings suggest that apical positioning of the top of the implant does not jeopardize bone crest and peri-implant tissue remodeling. However, less resorption of the lingual crest may be expected when implants are placed 2 mm subcrestally. Moreover, higher BIC values were found in implants placed subcrestally.

Histological, radiological and histomorphometric evaluation of immediate vs. non-immediate loading of a zirconia implant with surface treatment in a dog model.

OBJECTIVE: The aim of this study was to assess the performance of zirconia implants under immediate loading compared with delayed loading in dogs over 30-90 days. MATERIALS AND METHODS: Tooth extractions were made for the subsequent placement of dental implants at premolars P2, P3, P4 and molars M1 bilaterally in the dog mandible. Forty eight zirconia implants, 4 mm in diameter and 10 mm in length, were inserted, whose neck and body surfaces had been treated with femtosecond laser texturing; 24 implants were loaded immediately and 24 remained unloaded during the osseointegration period. Final radiographs were taken recording stability values before sacrifice at 30 or 90 days when sample removal for histological and histomorphometric analysis was performed. Bone-to-implant contact, crestal bone loss and implant stability were evaluated at these two study times. RESULTS: Bone-to-implant contact values after 30 days were 38.9% for immediately loaded implants and 32% for non-loaded implants. After 90 days, values increased to 65% for immediately loaded and 57.6% for non-loaded implants. After 30 days, there was more crestal bone lost in the non-loaded group (0.58 ± 0.28 mm) compared with the immediately loaded group (0.5 ± 0.3 mm). After 90 days, there was improved stability in both groups, but was lower in the immediately loaded group (0.5 ± 0.23 mm) compared with the non-loaded group (0.56 ± 0.28 mm). Initial implant stability values were -3.5 PTV at the moment of implant placement. Stability values after the first 30 days were -4 for immediately loaded implants and -3 for non-loaded. At 90 days, non-loaded implants showed -4.9, whereas immediately loaded showed -7.1. CONCLUSIONS: For the different parameters studied, zirconia implants treated with femtosecond laser and subjected to immediate loading showed better results compared with non-loaded implants in terms of BIC, crestal bone loss and implant stability.

Influence of biphasic ß-TCP with and without the use of collagen membranes on bone healing of surgically critical size defects. A radiological, histological, and histomorphometric study.

OBJECTIVES: The aim of this study was to investigate, by means of radiological and histomorphometric analysis, the effect of resorbable collagen membranes on critical size defects (CSD) in rabbit tibiae filled with biphasic calcium phosphate. MATERIALS AND METHODS: Three CSD of 6 mm diameter were created in both tibiae of 20 New Zealand rabbits and divided into three groups according to the filling material: Group A (Ossceram), Group B (Ossceram plus Alveoprotect membrane), and Group C (unfilled control group). Five animals from each group were sacrificed after 15, 30, 45, and 60 days. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. RESULTS: At the end of treatment, radiological analysis found that cortical defect closure was greater in Group B than Group A, and radiopacity was clearly lower and more heterogeneous in the Group A cortical defects than in Group B. There was no cortical defect closure in Group C. Histomorphometric evaluation showed significant differences in newly formed bone and cortical closure in Group B compared with Groups A and C, with the presence of higher density newly formed bone in cortical and medullar zones. There was no cortical defect closure or medullar bone formation in Group C. CONCLUSIONS: Biphasic calcium phosphate functioned well as a scaffolding material allowing mineralized tissue formation. Furthermore, the addiction of absorbable collagen membranes enhanced bone gain compared with non-membrane-treated sites.

Peri-implant tissue reactions to immediate nonocclusal loaded implants with different collar design: an experimental study in dogs.

PURPOSE: The aim of this study was to evaluate bone remodelling and soft tissue reactions around immediate nonocclusal loaded implants with different collar configuration in beagle dogs. MATERIAL AND METHODS: The mandibular bilateral second, third and fourth premolars of six beagle dogs were extracted. After 3 months of healing, four implants were placed in the mandibles of each dog. Randomly, two implants with a 1.5 mm polished surface collar (TSA, control group) and two implants with a 0.7 mm polished surface collar and 2.5 mm microthreaded area (TSAA, test group) were inserted. Both groups were treated with a minimal mucoperiosteal flap elevation approach. Impressions were taken and two single screw-retained restorations were inserted in each hemi-mandible 2 days after the implant placement. The animals were sacrificed at 1, 2 and 3 months (two specimens each), and biopsies were obtained. Samples were processed for ground sectioning. Histomorphometric analysis was carried out to compare buccal and lingual bone height loss and soft tissue behaviour between the two groups. RESULTS: Crestal bone resorption was significantly higher in the control group (P > 0.05). The establishment of the biological width showed similar outcomes for both groups. Only the distance from the top of the peri-implant mucosa to the apical portion of the barrier epithelium at lingual aspect was significantly more pronounced in the control group (P > 0.05). CONCLUSIONS: The alterations that occurred in the peri-implant tissues were related to the adaptation that occurred after the loading conditions in both groups. The microthread design might have an effect in maintaining the marginal bone loss against loading.

The effect of abutment dis/reconnections on peri-implant bone resorption: a radiologic study of platform-switched and non-platform-switched implants placed in animals.

OBJECTIVES: The purpose of this animal study was to radiologically measure the influence of abutment disconnection on bone resorption and to compare this influence on platform-switched vs. non-platform-switched implants. METHODS: The study design included extraction of all mandibular premolars in five canines . After 2 months, six implants were placed in each dog. Four of them were platform-switched (PS) implants and two were non-platform-switched (NPS) implants. Some or all of the abutments connected to the implants were disconnected at pre-ordained post-surgical intervals. Radiographs were taken at the time of implant placement and at every handling. The values for mesial (horizontal and vertical) and distal (horizontal and vertical) bone resorption were taken and compared for each implant at every abutment dis/reconnection. RESULTS: The average vertical bone resorption around NPS implants after four dis/reconnections was 1.09 mm (SD 0.25 mm), and the average horizontal bone resorption was 0.98 mm (SD 0.27 mm). The average vertical bone resorption around PS implants after four dis/reconnections was 0.24 mm, (SD 0.08 mm) and the average horizontal bone resorption was 0.24 mm (SD 0.13 mm). The difference of the average horizontal and vertical bone resorption around NPS (site D) and PS (site A) implants was statically significant (P < 0.05). The average mesial and distal bone resorption values around PS (site A) implant adjacent to a tooth were compared, and statically significant differences were found (P < 0.05). CONCLUSIONS: Implants with a PS design show less peri-implant bone resorption during the healing process and as their abutments are disconnected, than do comparably dis/reconnected NPS implants. The location of the PS implant next to a tooth may decrease radiographically visible peri-implant bone resorption significantly.

Biodegradation process of α-tricalcium phosphate and α-tricalcium phosphate solid solution bioceramics in vivo: a comparative study.

This article reports the structure and morphology of the in vivo interface between implants composed of either a tricalcium phosphate (αTCP) or αTCP doped with 3.0 wt% dicalcium silicate (αTCP(ss)) ceramic, and natural bone of rabbit tibias. Both interfaces developed a new bone layer in direct contact with the implants after 4 and 8 weeks of implantation. The specimens were examined using analytical scanning and transmission electron microscopy, up to the lattice plane resolution level. Degradation processes of the implants developed at the interfaces encouraged osseous tissue ingrowth into the periphery of the material, changing the microstructure of the implants. The ionic exchange initiated at the implant interface with the environment was essential in the integration process of the implant, through a dissolution­precipitation­transformation mechanism. The interfaces developed normal biological and chemical activities and remained reactive over the 8-week period. Organized collagen fibrils were found at the αTCP(ss)/bone interface after 4 weeks, whereas a collagen-free layer was present around the Si-free αTCP implants. These findings suggest that the incorporation of silicate ions into αTCP ceramic promotes processes of the bone remodeling at the bone/αTCP(ss) interface, hence the solubility rate of the aTCP(ss) material decreased.

Buccal bone crest dynamics after immediate implant placement and ridge preservation techniques: review of morphometric studies in animals.

PURPOSE: To review morphometric studies performed in animals assessing the dynamics of the buccal bone crest after immediate implant placement and ridge preservation techniques. MATERIAL AND METHOD: A bibliographic search in PubMed was performed. Studies that analyzed morphometrically in animals the buccal bone crest dynamics after immediate implant placement or ridge preservation techniques were included. Twenty-five studies met the inclusion criteria. RESULTS: Immediate implant placement does not prevent the resorption of the buccal bone crest. To minimize this resorption, 2 mm width of the buccal bone crest, palatal/lingual implant placement, and an adequate implant diameter for the width of the ridge are required. The regeneration of the gap after immediate implant placement limits the resorption of the buccal bone crest. Flap elevation and implant surface showed no relation with this resorption. Ridge preservation techniques associated with mucogingival surgery minimize buccal bone crest resorption. Biomaterials are more effective than autograft. CONCLUSIONS: Immediate implant placement does not prevent the resorption of the buccal bone crest after dental extraction. Ridge preservation techniques minimize this resorption.

In vitro study of force decay of latex and non-latex orthodontic elastics.

The aim of this study was to evaluate the force decay of two brands of orthodontic elastics, both offering latex and non-latex products. Samples were subjected to continuous stretching, measuring force at 5 seconds, 8 hours, and 24 hours in both dry and wet conditions. Five hundred samples were used, GAC® and Lancer® 0.25 inch and 4 oz, divided into testing sample sizes of n = 25 per group. For the dry test, elastics were kept stretched to three times their internal diameter for 5 seconds (initial force), 8 hours, and 24 hours; for the wet test, they were stretched for 8 and 24 hours. Both brands showed initial forces significantly greater than those specified by the manufacturers (P < 0.05). Comparing wet/dry conditions, there was a greater force loss in the wet medium than the dry. As for elastic composition (latex or non-latex), the only significant difference found was between Lancer elastics with and without latex in dry conditions, force loss being greater for latex-free elastics. Comparing brands, there was greater force loss with GAC than with Lancer. Comparing elastic force at the eight-hour mark and the twenty-four hour mark to the initial force (only in wet conditions), GAC latex and non-latex and Lancer latex elastics showed significantly less force at eight and twenty four hours than initially. On the other hand, Lancer non-latex was the only type of elastics that did not show a significant decrease in its initial elastic characteristics at eight hours in wet conditions. Nevertheless, Lancer non-latex did show significantly less force in wet conditions at twenty four-hours than the forces observed initially and at eight-hours.

Metallic ion content and damage to the DNA in oral mucosa cells of children with fixed orthodontic appliances.

Although the metal devices used in orthodontic treatments are manufactured highly resistance to corrosion, they may still suffer some localized corrosion resulting from the oral cavity conditions. The corrosion causes the release of metals from the alloys used for their manufacture. In this report, we evaluated the in vivo metal ions release of three alloys (stainless steel, titanium and nickel-free) usually used in the orthodontics treatments and its genotoxicity. We applied to 15 patients, between 12 and 16 years, 4 tubes and 20 brackets. Samples from oral mucosa were taken before the treatment and 30 days later. The concentration of the titanium, chromium, manganese, cobalt, nickel, molybdenum and iron were detected using inductively coupled plasma mass spectrometry (ICP-MS). The genotoxicity was measured with a comet assay (Olive moment). The oral mucosa cells in contact with the stainless steel alloy displayed the greatest titanium and manganese concentrations and those in contact with the nickel-free alloy presented the greatest concentration of chromium and iron. Both alloys, stainless steel and nickel-free, induced a higher DNA damage in the oral mucosa cells than the titanium alloy, in which the Olive moment was similar to controls. Based on the results of our study, we can conclude that titanium brackets and tubes are the most biocompatible of the three alloys.

Melatonin stimulates the growth of new bone around implants in the tibia of rabbits.

This study evaluated the effect of the topical application of melatonin in accelerating bone formation associated with implants 2 months after their application to the tibiae of rabbits. Twenty New Zealand rabbits were used. Twenty implants treated with melatonin and 20 control implants without melatonin were placed in the proximal metaphyseal area of each tibia. Studies of new bone formation were subsequently made at 15, 30, 45 and 60 days. Cortical width and cortical length of new bone formation were measured. Following implantation, an anteroposterior and lateral radiologic study was carried out. Collected samples were sectioned at 5 µm and stained using hematoxylin-eosin, Masson's trichromic and Gordon-Switt reticulin stains. After a 60 day treatment period, melatonin increased the length of cortical bone (95.13±0.42%) versus that around control implants (62.91±1.45%). Related to the perimeter of cortical bone of the tibiae, melatonin induced new bone 88.35±1.56% versus 60.20±1.67% in the control implants. Melatonin regenerated the width and length of cortical bone around implants in tibiae of rabbits more quickly than around control implants without the addition of melatonin.

Osteoblastic differentiating potential of dental pulp stem cells in vitro cultured on a chemically modified microrough titanium surface.

Titanium surface modification is critical for dental implant success. Our aim was to determine surfaces influence on dental pulp stem cells (DPSCs) viability and differentiation. Implants were divided into sandblasted/acid-etched (control) and sandblasted/acid-etched coated with calcium and magnesium ions (CaMg), supplied as composite (test). Proliferation was evaluated by MTT, differentiation checking osteoblastic gene expression, PGE2 secretion and matrix formation, inflammation by Interleukin 6 (IL-6) detection. MTT and IL-6 do not modify on test. A PGE2 increase on test is recorded. BMP2 is higher on test at early experimental points, Osterix and RUNX2 augment later. Alizarin-red S reveals higher matrix production on test. These results suggest that test surface is more osteoinductive, representing a start point for in vivo studies aiming at the construction of more biocompatible dental implants, whose integration and clinical performance are improved and some undesired effects, such as implant stability loss and further surgical procedures, are reduced.