Cannabis sativa smoke inhalation decreases bone filling around titanium implants: a histomorphometric study in rats

Cannabinoids: Therapeutic Perspectives for Management of Orofacial Pain, Oral Inflammation and Bone Healing-A Systematic Review

Cannabinoids, particularly cannabidiol (CBD) and tetrahydrocannabinol (THC), have been increasingly studied for their therapeutic applications in various medical fields. This systematic review aims to explore their role in oral surgery, focusing on pain management, inflammation control, and bone regeneration. A systematic review was conducted using the PRISMA framework to identify relevant studies from the PubMed, Scopus, and Web of Science databases published up to November 2024. The review included clinical and preclinical studies investigating the effects of cannabinoids on orofacial pain, oral inflammation, and bone healing. Data on study design, cannabinoid types, and relevant outcomes were extracted and analyzed. CBD was the most commonly studied compound, with other studies evaluating CB1/CB2 receptor agonists, THC, and cannabis smoke. Clinical trials showed mixed results: some studies found CBD effective in reducing dental or myofascial pain, while others found limited or non-superior outcomes compared to standard treatments (e.g., NSAIDs, corticosteroids). Among the four RCTs, three had a low risk of bias, and one moderate; all nine animal studies had a high risk of bias. in conclusion, preclinical and clinical studies suggest that cannabinoids represent a promising non-opioid alternative for pain management and for oral inflammation. Although some evidence suggests potential benefits of cannabinoids, particularly CBD, in oral health contexts, findings are derived from heterogeneous studies-many with high risk of bias. More high-quality, standardized clinical trials are necessary before recommending cannabinoids for routine dental practice.

Marijuana Use and Complication Risk After Tibia Shaft Fracture Fixation

OBJECTIVES

The aim of this study was to investigate the relationship between preoperative marijuana use and complications after tibia shaft fracture fixation.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Two academic Level I trauma centers.

PATIENT SELECTION CRITERIA

Adults age ≥18 years who underwent tibia shaft fracture (OTA/AO 42) fixation from 2014 to 2022 and had a minimum 3 months postoperative follow-up were included. Patients were considered marijuana users if they had current self-reported marijuana use or a urine toxicology screen positive for cannabinoids documented at initial presentation.

OUTCOME MEASURES AND COMPARISONS

Bivariate statistics and multivariate regression were used to evaluate the effect of marijuana use on 90-day postoperative thromboembolic and surgical complications, unplanned readmissions, and emergency department visits. Complications related to fracture union were evaluated in patients with ≥6 months follow-up. Multivariate analysis controlled for tobacco use, open fracture, and American Society of Anesthesiologist class ≥3.

RESULTS

Among 388 patients included in the study, the mean age was 37.6 years (range, 18-90), and most patients were men (66.5%). Ninety-six patients (25%) were identified as marijuana users. Marijuana users were significantly younger (30.5 years vs. 40 years, P < 0.001) and more likely to be men (79% vs. 62%, P = 0.002) and use tobacco currently (73% vs. 31%, P < 0.001) than nonusers. Marijuana users experienced higher rates of 90-day surgical complications (11.5% vs. 4.8%, P = 0.030) and deep infection (8.3% vs. 2.1%, P = 0.008) than nonusers. No significant difference was observed between groups in the rates of thromboembolic complications, nonunion, or delayed union ( P > 0.05). On multivariate analysis, marijuana use was not associated with odds of developing any 90-day surgical complication (odds ratios 2.01; 95% confidence intervals 0.83-4.84) or deep infection (odds ratios 2.97; 95% confidence interval 0.95-9.25).

CONCLUSIONS

Preoperative marijuana use was not found to be associated with risk of thromboembolic, surgical, or fracture union-related complications in patients undergoing tibia shaft fracture fixation.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Regenerative surgical therapy in a frequent cannabis consumer: A case study

BACKGROUND

There is substantial evidence that smokers present a less favorable response following regenerative periodontal surgery. However, there are no reports to date on the response to regenerative procedures in chronic cannabis smokers. In the present case study, we discuss the periodontal outcomes of reparative and regenerative surgical treatment in a cannabis consumer patient with generalized stage III grade C periodontitis.

METHODS AND RESULTS

We report the case of a young adult cannabis consumer patient diagnosed with generalized stage III grade C periodontitis who had a probing depth (PD) of ≥ 4 at 18% of sites and of ≥ 7 mm at 12% of sites and radiographically confirmed generalized interproximal bone loss with horizontal and angular defects that reached the middle and apical third of the roots. An appropriate sequence of therapy based on the recommendations in the Clinical Practice Guideline (CPG) involving reparative and regenerative surgical procedures (steps 1-3) was followed. Clinical outcomes at 6 months included a decrease in PD of up to 7 mm and radiographic evidence of newly formed bone in the bony defects.

CONCLUSION

The present case study demonstrates the use of regenerative periodontal procedures as part of a stepwise treatment approach, with different interventions at each step, to successfully manage intrabony periodontal defects in a healthy young adult male cannabis consumer.

KEY POINTS

Smoking is a well-documented dose-dependent risk factor for periodontal disease, with a demonstrated negative effect on periodontal therapy outcomes. However, the usefulness of regenerative periodontal therapy in cannabis smokers has not been established to date. This case presents new information in that it is the first report to show that appropriate periodontal treatment can stabilize the periodontal disease and that regenerative therapies were successful in healing intrabony periodontal defects in a healthy young adult cannabis user. The keys to successful management of this case are: -Attention to detail in all aspects of therapy. -Patient compliance as a co-therapist by maintaining effective plaque control. -Patient acceptance of supportive care recommendations. The primary limitations of this case study are: -The main limitation of this study is that a single clinical case study is too small to draw conclusions about regenerative treatment in patients who use cannabis. -The follow-up assessment times were not sufficient to determine the long-term success of regenerative surgery. -Patient compliance with oral hygiene recommendations and supportive care are key to achieving long-term success in regenerative therapy.

PLAIN LANGUAGE SUMMARY

Background: Smokers have a worse response to regenerative periodontal surgery. There are no reports on how cannabis smokers respond to regenerative procedures. This case study discusses how periodontal surgery worked in a young adult patient with severe periodontitis who was a frequent cannabis user. After 6 months of an appropriate sequence of therapy including strict regenerative surgical procedures, there was new bone filling in the bony defects.

CONCLUSIONS

This case shows that regenerative periodontal procedures can successfully treat intraosseous periodontal defects in a healthy young adult male cannabis user.

Effect of recreational cannabis use on bone mineral density: a systematic review

The recreational use of cannabis products has risen considerably worldwide over the past decade. As the cannabis legal market grows, a critical challenge has been to make substantiated claims about the benefits and adverse health problems triggered by cannabis exposure. Despite accumulating evidence from animal studies demonstrating the role of cannabinoids on bone metabolism, there are conflicting results in clinical literature regarding their effects on bone health outcomes.We undertook a systematic review to assess the evidence for the safety of cannabis use on bone health. We searched the databases MEDLINE, EMBASE, Cochrane Library, and Web of Science up to March 2023 for studies evaluating the effect of the recreational use of cannabis on the bone mineral density (BMD) of adults.Among the 2620 studies reviewed, three cross-sectional studies and one randomized controlled trial comprised 4032 participants from 18 to 60 years who met the inclusion criteria. Two studies showed that cannabis exposure decreased BMD, while the other 2 indicated no alteration. Despite the different study designs, the included studies showed a low risk of bias according to the Joanna Briggs Institute tool.Eligible studies present differences in cannabis products, administration routes, and exposure determination. Further longitudinal research is needed to establish multiple clinical predictors associated with potentially negative consequences of cannabis exposure, especially in vulnerable populations such as elderly individuals.

Examining the role of cannabinoids on osteoporosis: a review

PURPOSE

Prior research studies have shown that the endocannabinoid system, influenced by CBD and THC, plays a role in bone remodeling. As both the research on cannabis and use of cannabis continue to grow, novel medicinal uses of both its constituents as well as the whole plant are being discovered. This review examines the role of cannabinoids on osteoporosis, more specifically, the endocannabinoid system and its role in bone remodeling and the involvement of the cannabinoid receptors 1 and 2 in bone health, as well as the effects of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and synthetic cannabinoids on bone.

METHODS

A comprehensive literature search of online databases including PUBMED was utilized.

RESULTS

A total of 29 studies investigating the effects of cannabis and/or its constituents as well as the activation or inactivation of cannabinoid receptors 1 and 2 were included and discussed.

CONCLUSION

While many of the mechanisms are still not yet fully understood, both preclinical and clinical studies show that the effects of cannabis mediated through the endocannabinoid system may prove to be an effective treatment option for individuals with osteoporosis.

Marijuana in Orthopaedics: Effects on Bone Health, Wound-Healing, Surgical Complications, and Pain Management

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Marijuana use is on the rise in the United States, and there is a paucity of information on the effects of cannabis and its chemical constituents on bone health, wound-healing, surgical complications, and pain management.

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Current evidence suggests that cannabidiol (CBD) may enhance bone health and metabolism, while Δ9-tetrahydrocannabinol (Δ9-THC), the major psychoactive component in marijuana, has an inhibitory effect.

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Marijuana users are at higher risk for delayed bone-healing, demonstrate lower bone mineral density, are at increased risk for fracture, and may experience postoperative complications such as increased opioid use and hyperemesis.

Potential Mechanisms Underlying Marijuana-Associated Periodontal Tissue Destruction

While definitive evidence awaits, cannabis is emerging as a likely risk factor for periodontal tissue destruction. The mechanisms that underlie potential cannabis-induced or cannabis-enhanced periodontal diseases, however, remain to be elucidated. Herein, we 1) examine insights obtained from the endocannabinoid system, 2) summarize animal models of exposure to cannabinoid receptor agonists and antagonists, 3) review the evidence suggesting that cannabis and cannabis-derived molecules exert a profound influence on components of the oral microbiome, and 4) assess studies indicating that marijuana and phytocannabinoids compromise the immune response to plaque. Furthermore, we address how knowledge of cannabinoid influences in the oral cavity may be exploited to provide potential novel periodontal therapeutics, while recognizing that such medicinal approaches may be most appropriate for nonhabitual marijuana users. The suspected increase in susceptibility to periodontitis in marijuana users is multifaceted, and it is clear that we are only beginning to understand the complex toxicological, cellular, and microbial interactions involved. With marijuana consumption increasing across all societal demographics, periodontal complications of use may represent a significant, growing oral health concern. In preparation, an enhanced research response would seem appropriate.

Dronabinol inhibits alveolar bone remodeling in tooth movement of rats

INTRODUCTION

Orthodontic tooth movement is reliant on the process of bone remodeling, and a variety of medications impact the ability of teeth to move through bone. Marijuana is the most widely used recreational drug in the world, and early studies suggest the drug impacts bone remodeling as tetrahydrocannabinol binds to cannabinoid receptors which play a role in bone homeostasis. This study aimed to assess the impact of dronabinol on alveolar bone remodeling in rats with otherwise healthy tissue when subjected to orthodontic forces.

METHODS

Thirty male Sprague Dawley rats were equally allocated into 2 groups. Orthodontic appliances were placed in all animals, which consisted of a nickel-titanium coil ligated from the maxillary first molar to the central incisor. The appliance was activated to deliver a force to move teeth together. Over 21 days, daily injections of either dronabinol or the control (solvent) were given to the rats. Cephalometric analysis, histology, and bone remodeling profiles of both groups were analyzed and compared.

RESULTS

Teeth moved in both the dronabinol and control groups (P <0.05). Tooth movement in the control group followed the typical process of orthodontic tooth movement: periodontal width narrowing and bone resorption on the compression side of the tooth, with an overall decrease in the height of the alveolar bone. In contrast, the dronabinol group showed an abnormal response to tooth movement: no bone resorption on the compression side of the tooth, increased bone formation on the tension side, and the maintenance of the height of the alveolar crest. In the dronabinol group, there were also significantly more osteoclasts and osteoblasts in the alveolar bone than in the control group.

CONCLUSIONS

These results demonstrate that dronabinol attenuates orthodontic tooth movement by decreasing bone resorption, which could have implications for other bone-related recovery processes.

Effects of Marijuana Use in Patients with Orthopaedic Trauma

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The use of cannabis and cannabis-related products has increased dramatically in the last 2 decades. As states continue to legalize cannabis products, it is important for surgeons to understand the effects they may have on patients who have sustained orthopaedic trauma.

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Cannabinoids have been shown to decrease the severity of certain symptoms related to traumatic brain injury as well as posttraumatic stress disorder.

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Cannabinoids can modulate the body's endocannabinoid system, which can play an important role in bone homeostasis. Activation of cannabinoid receptors has been shown to be bone-protective in adults.

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Venous thromboembolism is a major concern for trauma patients. Cannabis use has been linked to overall increased rates of venous thromboembolism events.

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Literature regarding human-based cannabis studies is sparse; however, the growing field is opening new opportunities for research of this topic.

The Effects of Cannabis: Implications for the Surgical Patient

Background:

Cannabis use is increasingly prevalent. Cannabinoid receptors regulate pro-inflammatory cytokines, and compounds in marijuana exert diverse physiologic effects. As more patients use cannabis, clinicians should recognize implications of perioperative cannabis use. Although the role of cannabis use in perioperative pain control has been explored, little is known about its effect on perioperative wound healing or on hematologic, pulmonary, and cardiovascular physiology.

Methods:

We searched PubMed for English-language articles related to cannabis (ie, marijuana, cannabidiol oil, and tetrahydrocannabinol) and wound healing, cardiovascular, pulmonary, or hematologic outcomes, and surgery. Titles and abstracts were reviewed, and relevant articles were analyzed. Human, animal, and pathology studies were included. Editorials, case reports, and review articles were excluded.

Results:

In total, 2549 wound healing articles were identified; 5 human studies and 8 animal/pathology studies were included. Results were conflicting. An estimated 2900 articles related to cardiovascular effects were identified, of which 2 human studies were included, which showed tetrahydrocannabinol and marijuana caused tachycardia. A total of 142 studies regarding pulmonary effects were identified. Three human studies were included, which found no difference in respiratory complications. In total, 114 studies regarding hematologic effects were identified. The 3 included human studies found conflicting venous thromboembolism risks. The overall study quality was poor. Information about dose/duration, administration route, and follow-up was reported with variable completeness.

Conclusions:

Surgeons should consider effects of cannabis in the perioperative setting. Little is known about its perioperative effects on wound healing, or on cardiovascular, pulmonary, and hematologic physiology. Further research should elucidate the effects of administration route, dose, and timing of cannabis use among surgical patients.

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.

Interventions to prevent periodontal disease in tobacco-, alcohol-, and drug-dependent individuals

Substance abuse affects more than one sixth of the world's population. More importantly, the nature of the abuse and the type of addictive substances available to individuals is increasing exponentially. All substances with abusive potential impact both the human immuno-inflammatory system and oral microbial communities, and therefore play a critical role in the etiopathogenesis of periodontal diseases. Evidence strongly supports the efficacy of professionally delivered cessation counseling. Dentists, dental therapists, and hygienists are ideally placed to deliver this therapy, and to spearhead efforts to provide behavioral and pharmacologic support for cessation. The purpose of this review is to examine the biologic mechanisms underlying their role in disease causation, to understand the pharmacologic and behavioral basis for their habituation, and to investigate the efficacy of population-based and personalized interventions in prevention of periodontal disease.

Cannabinoid Use in Musculoskeletal Illness: a Review of the Current Evidence

PURPOSE OF REVIEW

The use of cannabinoids has increased since legalization of recreational and medical use in the USA. It is likely that many orthopaedic patients consume cannabinoid products during the traumatic or perioperative period. The purpose of this study was to investigate the pre-clinical data evaluating the mechanism of action of cannabidiol (CBD) and Δ9-Tetrahydrocannabinol (Δ9-THC) and to evaluate the current clinical data on the use of cannabinoids in musculoskeletal illness.

RECENT FINDINGS

Recent pre-clinical studies have demonstrated that cannabinoid use and the endocannabinoid system (ECS) has an important role in bone healing and bone homeostasis. There is data that suggests that the use of cannabidiol (CBD) may increase bone healing, whereas the use of Δ9-Tetrahydrocannabinol (Δ9-THC), the major psychoactive ingredient in marijuana, likely inhibits bone metabolism and repair. The clinical implications and consumption of marijuana by orthopaedic patients have not been thoroughly evaluated. Studies have demonstrated concern for negative cardiovascular and psychiatric effects caused by marijuana use, but have not yet elucidated outcomes in the orthopaedic literature. With the recent increase in advertising of CBD products and legalization of marijuana, it is likely that many orthopaedic patients are consuming cannabinoid products. The clinical implications and consumption of these products are unclear. We need more robust and well-designed clinical studies prior to making further recommendations to our patients on the consumption of these products.

Marijuana-Derived Cannabinoids Trigger a CB2/PI3K Axis of Suppression of the Innate Response to Oral Pathogens

Cannabis use is an emergent risk factor for periodontitis, a chronic bacterial-induced disease of the supporting structures of the teeth. However, the mechanisms by which marijuana exposure predisposes to periodontal tissue destruction have yet to be elucidated. Therefore, we examined the influence of physiologically relevant doses of major marijuana-derived phytocannabinoid subtypes (cannabidiol [CBD]; cannabinol [CBN]; and tetrahydrocannabinol [THC], 1.0 μg/ml) on the interactions of three ultrastructurally variant oral pathogens, Porphyromonas gingivalis, Filifactor alocis, and Treponema denticola with the immune system. CBD, CBN, and THC each suppressed P. gingivalis-induced IL-12 p40, IL-6, IL-8, and TNF release while enhancing the anti-inflammatory cytokine, IL-10, from human innate cells. Similar phenomena were observed in F. alocis- and T. denticola-exposed human monocytes and human gingival keratinocytes. Higher phytocannabinoid doses (≥5.0 μg/ml) compromised innate cell viability and inhibited the growth of P. gingivalis and F. alocis, relative to unexposed bacteria. T. denticola, however, was resistant to all cannabinoid doses tested (up to 10.0 μg/ml). Pharmaceutical inhibition and efficient gene silencing indicated that a common CB2/PI3K axis of immune suppression is triggered by phytocannabinoids in vitro. This pathway does not appear to perpetuate through the canonical GSK3β-dependent cholinergic anti-inflammatory pathway, the predominant endogenous inflammatory control system. In a repetitive, transient oral infection model, CBD also suppressed P. gingivalis-induced innate immune markers in wild-type mice, but not in CB2^−/− mice. If such phenomena occur in humans in situ, environmental cannabinoids may enhance periodontitis via direct toxic effects on specific oral bacteria; by compromising innate cell vitality; and/or through a suppressed innate response to periodontal pathogens involving a CB2/PI3K signaling lineage.

Cannabidiol-loaded microspheres incorporated into osteoconductive scaffold enhance mesenchymal stem cell recruitment and regeneration of critical-sized bone defects

Recruitment of mesenchymal stem cells (MSCs) to an injury site and their differentiation into the desired cell lineage are implicated in deficient bone regeneration. To date, there is no ideal structure that provides these conditions for bone regeneration. In the current study, we aim to develop a novel scaffold that induces MSC migration towards the defect site, followed by their differentiation into an osteogenic lineage. We have fabricated a gelatin/nano-hydroxyapatite (G/nHAp) scaffold that delivered cannabidiol (CBD)-loaded poly (lactic-co-glycolic acid) (PLGA) microspheres to critical size radial bone defects in a rat model. The fabricated scaffolds were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and then analyzed for porosity and degradation rate. The release profile of CBD from the PLGA microsphere and CBD-PLGA-G/nHAp scaffold was analyzed by fluorescence spectroscopy. We performed an in vitro assessment of the effects of CBD on cellular behaviors of viability and osteogenic differentiation. Radiological evaluation, histomorphometry, and immunohistochemistry (IHC) analysis of all defects in the scaffold and control groups were conducted following transplantation into the radial bone defects. An in vitro migration assay showed that CBD considerably increased MSCs migration. qRT-PCR results showed upregulated expression of osteogenic markers in the presence of CBD. Histological and immunohistochemical findings confirmed new bone formation and reconstruction of the defect at 4 and 12 week post-surgery (WPS) in the CBD-PLGA-G/nHAp group. Immunofluorescent analysis revealed enhanced migration of MSCs into the defect areas in the CBD-PLGA-G/nHAp group in vivo. Based on the results of the current study, we concluded that CBD improved bone healing and showed a critical role for MSC migration in the bone regeneration process.

Cannabidiol, a Major Non-Psychotropic Cannabis Constituent Enhances Fracture Healing and Stimulates Lysyl Hydroxylase Activity in Osteoblasts

Cannabinoid ligands regulate bone mass, but skeletal effects of cannabis (marijuana and hashish) have not been reported. Bone fractures are highly prevalent, involving prolonged immobilization and discomfort. Here we report that the major non-psychoactive cannabis constituent, cannabidiol (CBD), enhances the biomechanical properties of healing rat mid-femoral fractures. The maximal load and work-to-failure, but not the stiffness, of femurs from rats given a mixture of CBD and Δ(9) -tetrahydrocannabinol (THC) for 8 weeks were markedly increased by CBD. This effect is not shared by THC (the psychoactive component of cannabis), but THC potentiates the CBD stimulated work-to-failure at 6 weeks postfracture followed by attenuation of the CBD effect at 8 weeks. Using micro-computed tomography (μCT), the fracture callus size was transiently reduced by either CBD or THC 4 weeks after fracture but reached control level after 6 and 8 weeks. The callus material density was unaffected by CBD and/or THC. By contrast, CBD stimulated mRNA expression of Plod1 in primary osteoblast cultures, encoding an enzyme that catalyzes lysine hydroxylation, which is in turn involved in collagen crosslinking and stabilization. Using Fourier transform infrared (FTIR) spectroscopy we confirmed the increase in collagen crosslink ratio by CBD, which is likely to contribute to the improved biomechanical properties of the fracture callus. Taken together, these data show that CBD leads to improvement in fracture healing and demonstrate the critical mechanical role of collagen crosslinking enzymes.

The cannabinoid receptor type 1 is essential for mesenchymal stem cell survival and differentiation: implications for bone health

Significant loss of bone due to trauma, underlying metabolic disease, or lack of repair due to old age surpasses the body's endogenous bone repair mechanisms. Mesenchymal stem cells (MSCs) are adult stem cells which may represent an ideal cell type for use in cell-based tissue engineered bone regeneration strategies. The body's endocannabinoid system has been identified as a central regulator of bone metabolism. The aim of the study was to elucidate the role of the cannabinoid receptor type 1 in the differentiation and survival of MSCs. We show that the cannabinoid receptor type 1 has a prosurvival function during acute cell stress. Additionally, we show that the phytocannabinoid, Δ(9)-Tetrahydrocannabinol, has a negative impact on MSC survival and osteogenesis. Overall, these results show the potential for the modulation of the cannabinoid system in cell-based tissue engineered bone regeneration strategies whilst highlighting cannabis use as a potential cause for concern in the management of orthopaedic patients.

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.

Impact of cannabis sativa (marijuana) smoke on alveolar bone loss: a histometric study in rats

BACKGROUND

Cannabis sativa (marijuana) can interfere with bone physiopathology because of its effect on osteoblast and osteoclast activity. However, its impact on periodontal tissues is still controversial. The present study evaluates whether marijuana smoke affects bone loss (BL) on ligature-induced periodontitis in rats.

METHODS

Thirty male Wistar rats were used in the study. A ligature was placed around one of the mandible first molars (ligated teeth) of each animal, and they were then randomly assigned to one of two groups: control (n = 15) or marijuana smoke inhalation ([MSI] for 8 minutes per day; n = 15). Urine samples were obtained to detect the presence of tetrahydrocannabinol. After 30 days, the animals were sacrificed and decalcified sections of the furcation area were obtained and evaluated according to the following histometric parameters: bone area (BA), bone density (BD), and BL.

RESULTS

Tetrahydrocannabinol was positive in urine samples only for the rats of the MSI group. Non-significant differences were observed for unligated teeth from both groups regarding BL, BA, and BD (P >0.05). However, intragroup analysis showed that all ligated teeth presented BL and a lower BA and BD compared to unligated teeth (P <0.05). The intergroup evaluation of the ligated teeth showed that the MSI group presented higher BL and lower BD (P <0.05) compared to ligated teeth from the control group.

CONCLUSION

Considering the limitations of this animal study, cannabis smoke may impact alveolar bone by increasing BL resulting from ligature-induced periodontitis.

Cannabinoids and the skeleton: from marijuana to reversal of bone loss

The active component of marijuana, Delta(9)-tetrahydrocannabinol, activates the CB1 and CB2 cannabinoid receptors, thus mimicking the action of endogenous cannabinoids. CB1 is predominantly neuronal and mediates the cannabinoid psychotropic effects. CB2 is predominantly expressed in peripheral tissues, mainly in pathological conditions. So far the main endocannabinoids, anandamide and 2-arachidonoylglycerol, have been found in bone at 'brain' levels. The CB1 receptor is present mainly in skeletal sympathetic nerve terminals, thus regulating the adrenergic tonic restrain of bone formation. CB2 is expressed in osteoblasts and osteoclasts, stimulates bone formation, and inhibits bone resorption. Because low bone mass is the only spontaneous phenotype so far reported in CB2 mutant mice, it appears that the main physiologic involvement of CB2 is associated with maintaining bone remodeling at balance, thus protecting the skeleton against age-related bone loss. Indeed, in humans, polymorphisms in CNR2, the gene encoding CB2, are strongly associated with postmenopausal osteoporosis. Preclinical studies have shown that a synthetic CB2-specific agonist rescues ovariectomy-induced bone loss. Taken together, the reports on cannabinoid receptors in mice and humans pave the way for the development of 1) diagnostic measures to identify osteoporosis-susceptible polymorphisms in CNR2, and 2) cannabinoid drugs to combat osteoporosis.