Histomorphometric, Immunohistochemical and Microtomographic Comparison between Autogenous and Xenogenous Bone Blocks for Mandibular Lateral Augmentation in Rabbits

BACKGROUND

The volumetric and biological behaviors of equine block grafts compared with autogenous block grafts have not yet been assessed. Hence, the aim of the present study was to compare-by means of histomorphometry, immunohistochemistry and microtomography-the graft incorporation and remodeling processes of autogenous and equine xenogenous bone blocks used for mandibular lateral augmentation in rabbits.

METHODS

Autogenous bone grafts harvested from the iliac bony crest and equine block grafts were secured to the lateral aspect of the mandible angle of eighteen rabbits. The healing after 7, 20 and 60 days was assessed in six animals each period.

RESULTS

After 60 days, new bone was present 24.2 ± 11.2% and 31.6 ± 13.3% in the autograft and xenograft groups, respectively. A better integration to the recipient sites was observed in the autogenous compared with the xenogenous blocks.

CONCLUSIONS

Both xenogenous and autogenous bone blocks presented similar percentages of newly formed bone over time. However, bone volume, the quality of the grafted area and graft incorporation to the recipient sites were superior in the autogenous compared with the equine xenogenous graft sites.

Dental Implants With a Platform-Switched Morse Taper Connection and an Osteo Growth Induction Surface

AIM

The aim of this study was to analyze the clinical outcomes after using an innovative implant system characterized by a modern platform-switched Morse taper connection and an osteo growth induction titanium surface (a particular type of SLA surface). Peri-implant bone loss (PBL) and implant success rate were examined after a 1- to 3-year follow-up.

METHODS

The study was conducted as a cross-sectional analysis on all patients treated from January 2011 to December 2014 using CLC CONIC implants. Implants were divided into 3 main groups, based on the duration of the follow-up (1 year, 2 years, and 3 years), then subgrouped by diameter, length, and type of prosthetic rehabilitation to compare differences in PBL. X-rays were taken at the time of surgery, at prosthetic loading, at 1 year, and then annually thereafter. Previously-established success criteria were used to assess the implants. Frequency analyses and comparisons between the means (with 95% CI) were conducted for the statistical analysis of the data collected.

RESULTS

One hundred twenty patients met inclusion and exclusion criteria, and completed the follow-up, and were thus eligible for the study, with a total of 261 CLC CONIC implants. The mean follow-up was 22.45 months. No implants failed, giving an overall success rate of 100%. The average PBL at 1-year follow-up was 0.047 mm, at 2 years it was 0.128 mm, and at 3 years it was 0.236 mm.

CONCLUSIONS

The CLC CONIC implant system had a high success rate after 1 to 3 years of follow-up, in line with previous reports in the scientific literature. Combining platform switching with the Morse taper connection enabled stable bone levels to be achieved in the short to medium term.

The Biological Properties of OGI Surfaces Positively Act on Osteogenic and Angiogenic Commitment of Mesenchymal Stem Cells

Osteogenesis process displays a fundamental role during dental implant osteointegration. In the present work, we studied the influence of Osteon Growth Induction (OGI) surface properties on the angiogenic and osteogenic behaviors of Mesenchymal Stem cells (MSC). MSC derived from dental pulp and HUVEC (Human Umbilical Vein Endothelial Cells) were grown in on OGI titanium surfaces, and cell proliferation and DNA synthesis were evaluated by MTT [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide] test and DNA quantification. Gene expression has been performed in order to evaluate the presence of mRNA related to endothelial and osteogenesis markers. Moreover, morphological and biochemical analyses of osteogenesis commitments has been performed. On OGI surfaces, MSC and HUVEC are able to proliferate. Gene expression profiler confirms that MSC on OGI surfaces are able to express endothelial and osteogenic markers, and that these expression are higher compared the expression on control surfaces. In conclusion On OGI surfaces proliferation, expression and morphological analyses of angiogenesis-associated markers in MSC are promoted. This process induces an increasing on their osteogenesis commitment.

Osteo Growth Induction titanium surface treatment reduces ROS production of mesenchymal stem cells increasing their osteogenic commitment

Surface characteristics play a special role for the biological performance of implants and several strategies are available to this end. The OGI (Osteo Growth Induction) titanium surface is a surface, obtained by applying a strong acid onto the blasted surface. The aim of this in-vitro study is to evaluate in vitro the osteoproperties of OGI surfaces on Mesenchymal Stem cells derived from dental pulp. Our results confirm that this treatment exert a positive effect on mitochondrial homeostasis, as shown by a decrease in ROS production related to environmental stress on the mitochondria. Morphological and molecular biology analyses confirmed more over that the DPSC cultured on the OGI surfaces appeared more spread in comparison to those grown on control titanium surface and real time PCR and biochemical data clearly demonstrated the increase of osteoconductive properties of the OGI treatment. In conclusion, our results suggest that mesenchymal stem cells sensitively respond to surface properties related to OGI treatment enhancing their osteogenic activities.

Healing at implants placed in bone of different morphology: an experimental study in dogs

OBJECTIVE

To study osseointegration at implants installed using a standard bed preparation in sites of different bone morphology.

MATERIAL AND METHODS

In six Labrador dogs, all mandibular premolars and first molars were extracted. After 4 months of healing, flaps were elevated, and two recipient sites were prepared in each side of the mandible, one in the second premolar and the other in the molar regions. Bone morphology and final insertion torque were evaluated. Healing abutments were applied, and the flaps were sutured to allow a non-submerged healing. After 4 months, the animals were sacrificed and ground sections were obtained for histomorphometric analyses.

RESULTS

At the premolar sites, bone morphology Class 2 and at the molar regions Class 3 or 4 were identified. The final insertion torque was 50-55 Ncm at the premolar and 30-35 Ncm at the molar sites. Mean osseointegration in percentage reached 61.5 ± 11.5% and 63.3 ± 10.1% at the premolar and molar sites, respectively. Mineralized bone density evaluated from the implant surface up to a distance of about 0.6 mm lateral to the implant surface was 63.0 ± 7.4% and 65.4 ± 17.7% at the premolar and molar sites, respectively.

CONCLUSIONS

Similar implant bed preparations performed at premolar and molar sites with different bone morphology, yielding insertion torque values of about 30-35 and 50-55 Ncm, respectively, did not affect osseointegration after 4 months at non-submerged implants.

Microbiological assessment of the implant-abutment interface in different connections: cross-sectional study after 5 years of functional loading

OBJECTIVE

To evaluate the bacterial microflora present inside the implant connection and in the peri-implant sulcus fluid of healthy implants, and to analyze the relationships between these harboring sites for four different implant systems after at least 5 years of functional loading.

MATERIALS AND METHODS

A cross-sectional study was performed involving 40 patients treated with metal-ceramic cemented bridges supported by at least two healthy implants functionally loaded for 5 years. Four different implant-abutment connections were studied: external hexagon (control group), double internal hexagon (test group 1), internal hexagon with external collar (test group 2), and conical connection (test group 3). Samples for microbiological analysis were obtained from three types of sites: peri-implant sulci, connections' inside and abutments surface and, as control, gingival sulci of neighboring teeth. Quantitative real-time PCR was carried out for Total Bacterial Count and for 10 microorganisms: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Treponema denticola, Prevotella intermedia, Peptostreptococcus micros, Fusobacterium nucleatum, Campylobacter rectus, Eikenella corrodens, and Candida albicans. The response variables were percentage of positive sites and absolute bacterial load. The relations of the response variables with the type of connection and of sampling site were assessed using generalized estimating equations.

RESULTS

Regarding the analysis of positivity to bacteria in the peri-implant sulcus no significant differences were observed. Analyzing the connection's inside, none of the connection designs had the capacity to prevent microbiological leakage through the implant/abutment microgap. Test group 3 presented the lowest mean values for red complex bacteria and control group the highest, although differences were non-significant. Statistical significance was only reached for Treponema denticola in the bacterial load analysis inside the connection. Test groups 1 and 2 yielded lower values for orange complex bacteria but only for Peptostreptococos micros the differences resulted significant. Test groups 2 and 3 had significantly lower total bacterial counts in the peri-implant sulcus and inside the connection.

CONCLUSIONS

Outcomes suggested that all the analyzed connections resulted contaminated after 5 years of functional loading. However, the connection design might influence bacterial activity levels qualitatively and quantitatively, especially inside the implant connection.

[Treatment of periodontal patients - current clinical concepts]

The main goal of the treatment of patients with periodontitis is to establish adequate infection control. To satisfy demands for acceptable aesthetics and chewing function with good long-term prognosis in patients with periodontitis requires the establishment of adequate infection control. Pocket instrumentation (scaling and root planing with or without flap elevation), combined with effective self-performed supragingival plaque control measures, constitutes the basic treatment modalities.

Probe penetration in periodontal and peri-implant tissues: An experimental study in the beagle dog

BACKGROUND

Today, periodontal probing is the best diagnostic tool to assess the health status and attachment level of periodontal tissues. There are, however, doubts as to whether the same method could be used for implants. Experiments comparing peri-implant and periodontal probing provide conflicting results. The impact and interpretation of peri-implant probing are still not sufficiently known.

PURPOSE

The purpose of the present study was to further analyze the histological level of probe penetration in healthy periodontal and peri-implant tissues.

MATERIAL AND METHODS

In four beagle dogs, all mandibular premolars were extracted. Three months later, four experimental non-submerged implants were placed in each edentulous premolar region. Six months later, probing depth was determined at the buccal aspect at two of the implants and at the bilateral first mandibular molars. A pressure-controlled probe with a diameter of 0.4 mm and 0.2 N probing force was used. Following the probing depth assessment, a metal periodontal probe tip was inserted into the previously measured depth and attached to the implants and teeth using a composite material. Block biopsies were obtained and prepared for histometric examinations.

RESULTS

The findings showed that probing resulted in similar probe extension at implants and teeth, that the probe extension corresponded to the extension of the barrier epithelium and that the distance between the probe tip and the bone was about 1 mm in both peri-implant and periodontal tissues.

CONCLUSIONS

This experiment showed that under healthy conditions, the probe tip penetration in the soft tissues at teeth and implants is similar when a probing force of 0.2 N is used. Probing around implants using a moderate force is a valuable diagnostic tool in the maintenance of implant patients.