Osseointegration Pharmacology: A Systematic Mapping Using Artificial Intelligence

Clinical performance of osseointegrated implants could be compromised by the medications taken by patients. The effect of a specific medication on osseointegration can be easily investigated using traditional systematic reviews. However, assessment of all known medications requires the use of evidence mapping methods. These methods allow assessment of complex questions, but they are very resource intensive when done manually. The objective of this study was to develop a machine learning algorithm to automatically map the literature assessing the effect of medications on osseointegration. Datasets of articles classified manually were used to train a machine-learning algorithm based on Support Vector Machines. The algorithm was then validated and used to screen 599,604 articles identified with an extremely sensitive search strategy. The algorithm included 281 relevant articles that described the effect of 31 different drugs on osseointegration. This approach achieved an accuracy of 95%, and compared to manual screening, it reduced the workload by 93%. The systematic mapping revealed that the treatment outcomes of osseointegrated medical devices could be influenced by drugs affecting homeostasis, inflammation, cell proliferation and bone remodeling. The effect of all known medications on the performance of osseointegrated medical devices can be assessed using evidence mappings executed with highly accurate machine learning algorithms.

Effects of Zoledronic Acid on Orthodontic Tooth Movement in Rats

The purpose of this study was to assess the effects of the administration of zoledronic acid (ZA) during orthodontic movement in rats. A hundred and twenty male Wistar rats were applied force of 30 cN with spring closed nickel-titanium to move the upper right first molar to mesial. In the Control Movement group (CM), only tooth movement was performed; the Control Acid Zoledronic group (CAZ) received a single dose (0.1 mg/kg) of ZA; the Experimental Acid Zoledronic group (EAZ) received a single dose (0.1 mg/kg) one week prior to the start of tooth movement; and the Control Without movement group (CWM) that received no drug and without application of tooth movement. The animals were euthanized after 3, 7 and 14 days. Tooth movement was measured using a caliper, the number of osteoclasts using TRAP staining, the expression of mature and immature collagen using picrosirius staining, and the presence of hyaline areas and root resorption using HE. The data were compared using two-way ANOVA, Tukey HSD, Games-Howell and chi-squared test, at the 5% significance level. It was observed a smaller number of osteoclasts and greater percentage of hyaline area in the EAZ group. There was no difference among the groups regarding bone remodeling, root resorption and tooth movement for all observed times.

Medication-related osteonecrosis of the jaw. Introduction of a new modified experimental model

PURPOSE

To evaluate a modified experimental model for medication-related osteonecrosis of the jaw (MRONJ) through the upper right central incisor extraction followed by intravenous bisphosphonate administration.

METHODS

Forty five rats underwent the upper right central incisor tooth extraction were divided in 2 groups: Group I - experimental group, 30 rats received an intravenous administration protocol of zoledronic acid 35μg/kg into the tail vein every two weeks, totalizing four administrations, during eight weeks of administration, previously the extraction, and Group II - control group, 15 rats didn't received any medication before extraction. The groups were subdivided in postoperative periods: 14/28/42 days. Clinical analysis and microtomography were performed to verify the presence of osteonecrosis. In addition, descritive histological analysis of hematoxylin-eosin stained sections was performed to evaluate the presence of osteonecrosis or necrotic foci.

RESULTS

Twelve (40%) rats, from experimental group, showed clinical signs of MRONJ (p=0.005), however, all samples showed imaginologic findings like osteolysis and loss of integrity of the cellular walls (p≤0.001). Microscopic evaluation revealed osteonecrosis areas with microbial colonies and inflammatory infiltrate (p≤0.001). In the control group, all animals presented the chronology of a normal wound healing.

CONCLUSIONS

The presence of medication-related osteonecrosis of the jaw after maxillary central incisor extraction in rats. This new experimental model may be considered an option for the study of MRONJ.

Screw-type device diameter and orthodontic loading influence adjacent bone remodeling

OBJECTIVE

To evaluate the effect of diameter and orthodontic loading of a screw-type implantable device on bone remodeling.

MATERIALS AND METHODS

Screw-shaped devices of four distinct diameters, 1.6, 2, 3, and 3.75 mm, were placed into edentulous sites in five skeletally mature beagle dogs (n = 14/dog) following premolar extraction. Using a split-mouth design, devices on one side were loaded using calibrated 2N coil springs. Epifluorescent bone labels were administered intravenous prior to sacrifice. Bone-implant sections (∼ 70 μm) were evaluated to quantify bone formation rate (BFR), and other histomorphometric variables were assessed in the implant supporting bone.

RESULTS

The mean BFR ranged from 10.93 percent per year to 38.91 percent per year. BFR in the bone adjacent to the device was lower for the loaded 1.6-mm screws when compared with the nonloaded 1.6-mm screws (P < .01) and the loaded 2.0-, 3.0-, and 3.75-mm diameter screws (P < .01). No significant differences in BFR were noted, regardless of loading condition, between the 2.0-, 3.0-, and 3.75-mm diameter screws.

CONCLUSIONS

We detected a dramatic reduction in bone remodeling. Although orthodontic loading of 2N did not alter bone remodeling associated with screws with a 2.0-mm diameter or larger, it did decrease bone remodeling adjacent to a loaded 1.6-mm screw. The long-term effect of this diminished remodeling should be further investigated.

Animal model for medication-related osteonecrosis of the jaw with precedent metabolic bone disease

Despite the fact that the medications used to treat abnormal bone conditions often induce osteonecrosis of the jaw (ONJ), previous attempts to establish an animal model for ONJ have shown insufficient consideration for this important prerequisite for the development of the disease. The purpose of this study was to establish an animal model with the most common metabolic bone disease, osteoporosis. Ninty-six rats were randomly divided into ovariectomy (Ov) group (n=48) and sham-operated group (n=48). Six weeks after Ov or sham surgery, rats in each group were subdivided into bisphosphonate group (n=36 each) and control group (n=12 each) and injected with zoledronic acid and normal saline, respectively, once a week. After additional 6weeks, surgical intervention was performed, and the injections were continued for 8 more weeks. The animals were then sacrificed for further macroscopic, histological, histomorphometric, radiological, and bone biomarker investigations. As histologically determined, the Ov group (77.8%) showed higher ONJ prevalence compared to the sham group (47.2%; P<0.05). Micro-structural and histomorphometric assessments revealed that rats with ONJ (ONJ group) presented with deteriorated bone architectures with higher necrotic bone fraction and lower number of osteoclasts (P<0.05). Compared to the sham-operated ONJ group, the Ov ONJ group showed significantly lower values of Tb.N, Tb.Sp, Conn.D, N.Oc/T.Ar, and TRACP 5b and CTX/TRACP (P<0.05). The ovariectomized rat model in this study successfully mimicked human ONJ lesions with an underlying bone disease and showed different bone characteristics than that of the previous ONJ model. Based on the differences, further researches for investigating pathophysiology of ONJ, including various pharmacological responses for deteriorated bone environment, are required.

Animal models for bisphosphonate-related osteonecrosis of the jaws--an appraisal

The prolonged use of bisphosphonates has been shown to cause a condition termed 'bisphosphonate related osteonecrosis of the jaws' (BRONJ). BRONJ is a disease entity which has only been described relatively recently, and its multi-factorial aetiology is yet to be fully elucidated. Therefore, the treatment of BRONJ lesions remains a challenge, and animal models are necessary to assist researchers in better understanding the disease. This has led to the recent publication of a number of studies utilising a variety of animal models of BRONJ. This review outlines the factors to be considered when selecting an animal model for BRONJ and discusses the current literature in this rapidly progressing field of research. It is important to consider the applicability of a given model to the clinical condition presenting in humans, and to this end, thorough characterisation of the clinical, histological, radiographic and systemic features is necessary. The development of a clinical lesion is an important consideration in terms of choosing a relevant model, and it appears clear that surgical manipulation, generally involving tooth extraction, is necessary for successful induction of the classic 'clinical' lesion of BRONJ.