Periimplant Bone Healing under Experimental Hepatic Osteodystrophy Induced by a Choline-Deficient Diet: A Histomorphometric Study in Rats

Bone healing around titanium implants in a preclinical model of bile duct ligation-induced liver injury

Objectives

Chronic liver disease increases the risk for periodontal disease and osteoporotic fractures, but its impacts on bone regeneration remain unknown. Herein, we studied the impact of liver cirrhosis on peri‐implant bone formation.

Material and Methods

A total of 20 male Wistar rats were randomly divided into two groups: one with the common bile duct ligated (BDL) and the respective sham‐treated control group (SHAM). After four weeks of disease induction, titanium mini‐screws were inserted into the tibia. Successful induction of liver cirrhosis was confirmed by the presence of clinical symptoms. Another four weeks later, peri‐implant bone volume per tissue volume (BV/TV) and bone‐to‐implant contact (BIC) were determined by histomorphometric analysis.

Results

Peri‐implant bone formation was not significantly different between the SHAM and BDL groups. In the cortical compartment, the median percentage of peri‐implant new bone was 10.1% (95% CI of mean 4.0–35.7) and 22.5% (13.8–30.6) in the SHAM and BDL groups, respectively (p = .26). Consistently, the new bone in direct contact with the implant was 18.1% (0.4–37.8) and 23.3% (9.2–32.8) in SHAM and BDL groups, respectively (p = .38). When measuring the medullary compartment, the new bone area was 7.1% (4.8–10.4) and 10.4% (7.2–13.5) in the SHAM and BDL groups, respectively (p = .17). Medullary new bone in direct contact with the implant was 10.0% (1.2–50.4) and 20.6% (16.8–35.3) in SHAM and BDL groups, respectively, and thus comparable between the two groups (p = .46).

Conclusions

Bile duct ligation has no significant impact on the early stages of peri‐implant bone formation.

Fluoride exposure altered metabolomic profile in rat serum

It is well known that serum is an ideal and potential choice to reflect the toxicity of fluoride. However, the effects of fluoride on serum metabolome have not been reported until now. In this study, the models of 3-week-old rats exposed fluoride by breast milk and 11-week-old rats exposed fluoride via breast milk and drinking water containing sodium fluoride (100 mg/L) were established. Using Ultra Performance Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (UPLC-MS/MS), as compared with control group, 28 negative (NEG) and 52 positive (POS) metabolites were significantly up-regulated, meanwhile 30 NEG and 21 POS significantly down-regulated metabolites were found in serum of 3-week-old rats exposed to fluoride. For 11-week-old fluorosis rats, there were 119 NEG and 65 POS metabolites significantly increased, and 7 NEG, 5 POS metabolites were obviously decreased. Importantly, nicotinamide, adenosine, 1-Oleoyl-sn-glycero-3-phosphocholine (OGPC), and 1-Stearoyl-sn-glycerol 3-phosphocholine (SGPC) were shared by two models. The metabolites of urea cycle, such as urea and N2-Acetyl-l-ornithine, betaine as a methyl donor, were regarded to reflect the fluorosis degree. These metabolites could be the potential markers of fluorosis, contributing to the prevention and treatment of fluorosis.

Research on implants and osseointegration

Osseointegration was originally defined as a direct structural and functional connection between ordered living bone and the surface of a load-carrying implant. It is now said that an implant is regarded as osseointegrated when there is no progressive relative movement between the implant and the bone with which it is in direct contact. Although the term osseointegration was initially used with reference to titanium metallic implants, the concept is currently applied to all biomaterials that have the ability to osseointegrate. Biomaterials are closely related to the mechanism of osseointegration; these materials are designed to be implanted or incorporated into the living system with the aims to substitute for, or regenerate, tissues and tissue functions. Objective evaluation of the properties of the different biomaterials and of the factors that influence bone repair in general, and at the bone tissue-implant interface, is essential to the clinical success of an implant. The Biomaterials Laboratory of the Oral Pathology Department of the School of Dentistry at the University of Buenos Aires is devoted to the study and research of the properties and biological effects of biomaterials for dental implants and bone substitutes. This paper summarizes the research work resulting from over 25 years' experience in this field. It includes studies conducted at our laboratory on the local and systemic factors affecting the peri-implant bone healing process, using experimental models developed by our research team. The results of our research on corrosion, focusing on dental implants, as well as our experience in the evaluation of failed dental implants and bone biopsies obtained following maxillary sinus floor augmentation with bone substitutes, are also reported. Research on biomaterials and their interaction with the biological system is a continuing challenge in biomedicine, which aims to achieve optimal biocompatibility and thus contribute to patient health.

Phosphatidylcholine metabolism and choline kinase in human osteoblasts

There is a paucity of information about phosphatidylcholine (PC) biosynthesis in bone formation. Thus, we characterized PC metabolism in both primary human osteoblasts (HOB) and human osteosarcoma MG-63 cells. Our results show that the CDP-choline pathway is the only de novo route for PC biosynthesis in both HOB and MG-63 cells. Both CK activity and CKα expression in MG-63 cells were significantly higher than those in HOB cells. Silencing of CKα in MG-63 cells had no significant effect on PC concentration but decreased the amount of phosphocholine by approximately 80%. The silencing of CKα also reduced cell proliferation. Moreover, pharmacological inhibition of CK activity impaired the mineralization capacity of MG-63 cells. Our data suggest that CK and its product phosphocholine are required for the normal growth and mineralization of MG-63 cells.

Systematic review of pre-clinical models assessing implant integration in locally compromised sites and/or systemically compromised animals

OBJECTIVE

The aim was to systematically search the dental literature for pre-clinical models assessing implant integration in locally compromised sites (part 1) and systemically compromised animals (part 2), and to evaluate the quality of reporting of included publications.

METHODS

A Medline search (1966-2011) was performed, complimented by additional hand searching. The quality of reporting of the included publications was evaluated using the 20 items of the ARRIVE (Animals in Research In Vivo Experiments) guidelines.

RESULTS

One-hundred and seventy-six (part 1; mean ARRIVE score = 15.6 ± 2.4) and 104 (part 2; 16.2 ± 1.9) studies met the inclusion criteria. The overall mean score for all included studies amounted to 15.8 ± 2.2. Housing (38.3%), allocation of animals (37.9%), numbers analysed (50%) and adverse events (51.4%) of the ARRIVE guidelines were the least reported. Statistically significant differences in mean ARRIVE scores were found depending on the publication date (p < 0.05), with the highest score of 16.7 ± 1.6 for studies published within the last 2 years.

CONCLUSIONS

A large number of studies met the inclusion criteria. The ARRIVE scores revealed heterogeneity and missing information for selected items in more than 50% of the publications. The quality of reporting shifted towards better-reported pre-clinical trials within recent years.