Effect of meloxicam and diclofenac sodium on peri-implant bone healing in rats

The effect of drugs on implant osseointegration- A narrative review

OBJECTIVE

This narrative review aims to investigate the effects of drugs on implant osseointegration, analyzing their potential positive or negative impact on the direct structural and functional connection between bone and load-carrying implants.

BACKGROUND

The review seeks to provide a comprehensive understanding of osseointegration, which refers to the successful integration of an implant with living bone, resulting in no progressive relative movement between them. Exploring the effects of drugs on implant osseointegration is crucial for optimizing outcomes and enhancing patient care in orthopedic implant procedures.

METHODS

Relevant studies on the effects of drugs on implant osseointegration were identified through a literature search. Electronic databases, including PubMed, Embase, and Google Scholar, were utilized, employing appropriate keywords and MeSH terms related to osseointegration, implants, and drug interventions. The search was limited to English studies.

DISCUSSION

This overview presents a detailed analysis of the effects of drugs on implant osseointegration. It explores drugs such as bisphosphonates, teriparatide, statins, angiotensin-converting enzyme inhibitors, beta-blockers, nitrites, and thiazide diuretics as promoters of osseointegration. Conversely, loop diuretics, non-steroidal anti-inflammatory drugs, corticosteroids, cyclosporine A, cisplatin, methotrexate, antibiotics, proton pump inhibitors (PPIs), antiepileptics, selective serotonin reuptake inhibitors (SSRIs), and anticoagulants are discussed as inhibitors of the process. The role of vitamin D3 remains uncertain. The complex relationship between drugs and the biology of implant osseointegration is emphasized, underscoring the need for further in vitro and in vivo studies to validate their effects CONCLUSION: This narrative review contributes to the literature by providing an overview of the effects of drugs on implant osseointegration. It highlights the complexity of the subject and emphasizes the necessity for more extensive and sophisticated studies in the future. Based on the synthesis of the reviewed literature, certain drugs, such as bisphosphonates and teriparatide, show potential for promoting implant osseointegration, while others, including loop diuretics and certain antibiotics, may impede the process. However, additional research is required to solidify these conclusions and effectively inform clinical practice.

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.

Bone and Cartilage Interfaces With Orthopedic Implants: A Literature Review

The interface between a surgical implant and tissue consists of a complex and dynamic environment characterized by mechanical and biological interactions between the implant and surrounding tissue. The implantation process leads to injury which needs to heal over time and the rapidity of this process as well as the property of restored tissue impact directly the strength of the interface. Bleeding is the first and most relevant step of the healing process because blood provides growth factors and cellular material necessary for tissue repair. Integration of the implants placed in poorly vascularized tissue such as articular cartilage is, therefore, more challenging than compared with the implants placed in well-vascularized tissues such as bone. Bleeding is followed by the establishment of a provisional matrix that is gradually transformed into the native tissue. The ultimate goal of implantation is to obtain a complete integration between the implant and tissue resulting in long-term stability. The stability of the implant has been defined as primary (mechanical) and secondary (biological integration) stability. Successful integration of an implant within the tissue depends on both stabilities and is vital for short- and long-term surgical outcomes. Advances in research aim to improve implant integration resulting in enhanced implant and tissue interface. Numerous methods have been employed to improve the process of modifying both stability types. This review provides a comprehensive discussion of current knowledge regarding implant-tissue interfaces within bone and cartilage as well as novel approaches to strengthen the implant-tissue interface. Furthermore, it gives an insight into the current state-of-art biomechanical testing of the stability of the implants. Current knowledge reveals that the design of the implants closely mimicking the native structure is more likely to become well integrated. The literature provides however several other techniques such as coating with a bioactive compound that will stimulate the integration and successful outcome for the patient.

The effects of a nonsteroidal anti-inflammatory drug on the degree of titanium implant osseointegration

OBJECTIVE

The aim of this study was to histologically examine the effects of a nonsteroidal anti-inflammatory drug, namely diclofenac sodium (DCS), on the extent of the bone-implant contact (BIC) of titanium implants after four weeks of osseointegration period in a rodent model.

MATERIAL & METHODS

Fourteen female Sprague-Dawley rats were divided into two groups: the control (n = 7) and experimental (DCS) groups. Fourteen machine-surfaced titanium implants were placed in the right tibial bones of the rats. The DCS (2 mg/kg) was administered by means of oral gavage to the experimental group for 14 days after four weeks of osseointegration. No medication was administered to the control group throughout the six-week study period. At the end of the study, the rodents were sacrificed and block sections were obtained for histologic evaluation.

RESULTS

The mean BIC ratios for the control and DCS groups were 64.15 ± 6.31% and 61.10 ± 6.08%, respectively. No statistically significant difference in terms of the BIC ratios was found between the two groups.

CONCLUSION

The results of this study demonstrate that DCS did not impair the BIC of the implants after four weeks of osseointegration.

Postoperative Administration of Alpha-tocopherol Enhances Osseointegration of Stainless Steel Implants: An In Vivo Rat Model

BACKGROUND

Alpha-tocopherol, a well-known antioxidative agent, may have a positive effect on bone formation during the remodeling phase of secondary fracture healing. Fracture healing and osseointegration of implants share common biological pathways; hence, alpha-tocopherol may enhance implant osseointegration.

QUESTIONS/PURPOSES

This experimental study in rats assessed the ability of alpha-tocopherol to enhance osseointegration of orthopaedic implants as determined by (1) pull-out strength and removal torque and (2) a histomorphological assessment of bone formation. In addition, we asked, (3) is there a correlation between the administration of alpha-tocopherol and a reduction in postoperative oxidative stress (as determined by malondialdehyde, protein carbonyls, reduced and oxidized glutathione and their ratio, catalase activity and total antioxidant capacity) that develops after implantation of an orthopaedic implant?

METHODS

This blinded study was performed in study and control groups, each consisting of 15 young adult male Wistar rats. On Day 0, a custom-designed stainless-steel screw was implanted in the proximal metaphysis of both tibias of all rats. On Day 1, animals were randomized to receive either alpha-tocopherol (40 mg/kg once per day intraperitoneally) or saline (controls). Animals were treated according to identical perioperative and postoperative protocols and were euthanized on Day 29. All animals completed the study and all tibias were suitable for evaluation. Implant pullout strength was assessed in the right tibias, and removal torque and histomorphometric evaluations (that is, volume of newly formed bone surrounding the implant in mm, percentage of newly formed bone, percentage of bone marrow surrounding the implant per optical field, thickness of newly formed bone in μm, percentage of mineralized bone in newly formed bone, volume of mature newly formed bone surrounding the implant in mm and percentage of mineralized newly formed bone per tissue area) were performed in the left tibias. The plasma levels of alpha-tocopherol, malondialdehyde, protein carbonyls, glutathione, glutathione disulfide, catalase, and the total antioxidant capacity were evaluated, and the ratio of glutathione to oxidized glutathione was calculated.

RESULTS

All parameters were different between the alpha-tocopherol-treated and control rats, favoring those in the alpha-tocopherol group. The pullout strength for the alpha-tocopherol group (mean ± SD) was 124.9 ± 20.7 newtons (N) versus 88.1 ± 12.7 N in the control group (mean difference -36.7 [95% CI -49.6 to -23.9]; p < 0.001). The torque median value was 7 (range 5.4 to 8.3) versus 5.2 (range 3.6 to 6 ) N/cm (p < 0.001). The newly formed bone volume was 29.8 ± 5.7 X 10 versus 25.2 ± 7.8 X 10 mm (mean difference -4.6 [95% CI -8.3 to -0.8]; p = 0.018), the percentage of mineralized bone in newly formed bone was 74.6% ± 8.7% versus 62.1% ± 9.8% (mean difference -12.5 [95% CI -20.2 to -4.8]; p = 0.003), the percentage of mineralized newly formed bone per tissue area was 40.3 ± 8.6% versus 34.8 ± 9% (mean difference -5.5 [95% CI -10.4 to -0.6]; p = 0.028), the glutathione level was 2 ± 0.4 versus 1.3 ± 0.3 μmol/g of hemoglobin (mean difference -0.6 [95% CI -0.9 to -0.4]; p < 0.001), the median glutathione/oxidized glutathione ratio was 438.8 (range 298 to 553) versus 340.1 (range 212 to 454; p = 0.002), the catalase activity was 155.6 ± 44.6 versus 87.3 ± 25.2 U/mg Hb (mean difference -68.3 [95% CI -95.4 to -41.2]; p < 0.001), the malondialdehyde level was 0.07 ± 0.02 versus 0.14 ± 0.03 μmol/g protein (mean difference 0.07 [95% CI 0.05 to 0.09]; p < 0.001), the protein carbonyl level was 0.16 ± 0.04 versus 0.27 ± 0.08 nmol/mg of protein (mean difference -0.1 [95% CI 0.05 to 0.15]; p = 0.002), the alpha-tocopherol level was 3.9 ± 4.1 versus 0.9 ± 0.2 mg/dL (mean difference -3 [95% CI -5.2 to -0.7]; p = 0.011), and the total antioxidant capacity was 15.9 ± 3.2 versus 13.7 ± 1.7 nmol 2,2-diphenyl-1-picrylhydrazyl radical/g of protein (mean difference -2.1 [95% CI -4.1 to -0.18]; p = 0.008).

CONCLUSIONS

These results using an in vivo rat model support that postoperatively administered alpha-tocopherol can enhance the osseointegration of an orthopaedic implant, although a cause and effect relationship between the administration of alpha-tocopherol and a reduction in postoperative stress cannot be securely established.

CLINICAL RELEVANCE

These findings suggest that postoperative administration of alpha-tocopherol is a promising approach to enhance osseointegration of orthopaedic implants in patients. Further studies with different animal models and/or different implants and those evaluating the alpha-tocopherol dose response are needed before performing clinical trials that will examine whether these promising, preliminary results can be extrapolated to the clinical setting as well.

The effect of non-steroidal anti-inflammatory drugs on the osteogenic activity in osseointegration: a systematic review

Non-steroidal anti-inflammatory drugs are commonly used in implant dentistry for management of post-operative pain. The objective of this systematic review was to analyse the effect of non-steroidal anti-inflammatory drugs on the osteogenic activity of osteoblasts with an emphasis on its effect on osseointegration. A systematic literature search for in vitro, animal models, and clinical trials was conducted using Ovid, PubMed, Scopus, and Web of Science databases. Articles published since the introduction of selective COX-2 inhibitors, between January 1999 and July 2018, were selected. The integrated search followed the PRISMA statement with the following key terms: non-steroidal anti-inflammatory drug/s, titanium, osseointegration, and osteoblast. The review is registered at PROSPERO database: CRD42016051448. The titles and abstracts of each research article in the initial search (n = 875) were independently screened by two reviewers. A third independent reviewer reviewed the articles that were included by one but excluded by the other reviewer. This resulted in the cataloguing of 79 full-text manuscripts where the articles were assessed for the following criteria: the study investigates the effects of NSAIDs on osteoblasts, explores the COX pathway and its effect on osteogenic activity, and compares the effects of NSAIDs on osteoblasts with a control group. A total of 13 articles have been included for qualitative synthesis. There is a lack of consensus in the literature to explicitly conclude that there is a relationship between the use of post-operative NSAIDs and failed osseointegration; however, osseointegration does not appear to be negatively affected by NSAIDs in the human clinical studies.

Evaluation of Effect of Low-Dose Methotrexate on Osseointegration of Implants: A Biomechanical Study on Dogs

Background:

Methotrexate (MTX) is an immunosuppressive drug, widely used in inflammatory disturbances including rheumatoid arthritis. However, there is no consensus regarding the effect of MTX on implant osseointegration.

Objective:

The purpose of this experimental study was to investigate the effect of low dose MTX on Bone-Implant Contact (BIC) of dogs.

Methods:

Six mandibular premolar teeth (bilateral) of 8 mature dogs were extracted. After 3 months of healing, 6 implants (bone level, resorbable blast media surface) were inserted into the mandible of each dog (3 in each side). Dogs were randomly divided into a study group (receiving 2.5 mg/week MTX orally, 3 times per week for 4 weeks) and a control group each containing 4 dogs. In the 1^st week, postoperative BIC was evaluated in 4 dogs, two from each group. In the 4^th week, reverse torque and BIC were evaluated in the remaining 4 dogs. Data were analyzed with two-way ANOVA test for 95% confidence interval.

Results:

The reverse torque test of the 4^th week, showed a satisfying osseointegration. Histopathologic evaluation revealed that the BIC was significantly higher in the control group in comparison to the MTX group in the 1^st and 4^th week. In addition, the BIC of both groups were significantly increased in the 4^th week in comparison to the 1^st week in both groups.

Conclusion:

MTX has the potential to interfere with osseointegration process.

Systemic drugs that influence titanium implant osseointegration

Titanium implants are widely used on an increasing number of patients in orthopedic and dental medicine. Despite the good survival rates of these implants, failures that lead to important socio-economic consequences still exist. Recently, research aimed at improving implant fixation, a process called osseointegration, has focused on a new, innovative field: systemic delivery of drugs. Following implant fixation, patients receive systemic drugs that could either impair or enhance osseointegration; these drugs include anabolic and anti-catabolic bone-acting agents in addition to new treatments. Anabolic bone-acting agents include parathyroid hormone (PTH) peptides, simvastatin, prostaglandin EP4 receptor antagonist, vitamin D and strontium ranelate; anti-catabolic bone-acting agents include compounds like calcitonin, biphosphonates, RANK/RANKL/OPG system and selective estrogen receptor modulators (SERM). Examples of the new therapies include DKK1- and anti-sclerostin antibodies. All classes of treatments have proven to possess positive impacts such as an increase in bone mineral density and on osseointegration. In order to prevent complications from occurring after surgery, some post-operative systemic drugs are administered; these can show an impairment in the osseointegration process. These include nonsteroidal anti-inflammatory drugs, proton pump inhibitors and selective serotonin reuptake inhibitors. The effects of aspirin, acetaminophen, opioids, adjuvants, anticoagulants and antibiotics in implant fixations are not fully understood, but studies are being carried out to investigate potential ramifications. It is currently accepted that systemic pharmacological agents can either enhance or impair implant osseointegration; therefore, proper drug selection is essential. This review aims to discuss the varying effects of three different classes of treatments on improving this process.

Pre- and post-operative management of dental implant placement. Part 1: management of post-operative pain

Although dental implant placements have high success rates and a low incidence of morbidity, post-operative pain and complications with the healing process have been reported. There is little guidance available regarding optimal pre- and post-operative management of dental implant placement. This first paper discusses the mechanisms of pain associated with dental implant placement and offers guidance to clinicians on optimal pre- and post-operative pain management regimes. The second paper aims to discuss pre- and post-operative means of reducing the risk of early healing complications.

Evaluation of the effects of two different bone resorption inhibitors on osteoclast numbers and activity: An animal study

Background:

The aim of this study was to evaluate the effects of bone resorption inhibitors, doxycycline (DOX) and erythromycin (EM), on osseous wound healing in rat alveolar socket.

Materials and Methods:

In this randomized controlled trial, 45 8–10-week-old male Wistar rats had their maxillary right molar extracted. They were divided into three groups of 15. In Group 1 normal saline, Group 2 DOX, and Group 3 EM were administered at the doses of 5 ml/kg/day, 5 mg/kg/day, and 2 mg/kg/day, respectively, for 7 consecutive days. The rats were sacrificed 7, 14, and 21 days after surgery. Real-time polymerase chain reaction was employed to evaluate the mRNA expression of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) and immunohistochemical staining for tartrate-resistant acid phosphatase (TRAP) to determine osteoclasts. The data were analyzed by one-way analysis of variance followed by Tukey's post hoc test using SPSS version 20. Significant level was set at 0.05.

Results:

The results showed that when drug-treated groups compared to control groups, RANKL gene expression significantly decreased, TRAP⁺ cells decreased on day 7. The RANKL/OPG ratios in the first two weeks in the test groups were significantly lower than the control group. There was no significant difference in the studied indices between DOX and EM groups.

Conclusion:

Following administration of DOX and EM, the number of osteoclasts and RANKL/OPG ratio decreased suggesting their anti-osteoclastogenesis activity. These two drugs have no advantage over each other in increasing the bone formation.

Effects of Nonsteroidal Anti-inflammatory Drugs on Osseointegration: A Review

The purpose of this study was to review the effects of nonsteroidal anti-inflammatory drugs on osseointegration and determine whether they cause failures in dental implants and whether patients who use them chronically can receive dental implants safely. A bibliographic electronic search was performed using the Cochrane Library, PubMed, and Medline databases, selecting articles published between January 1982 and December 2012. The search included the following keywords, either alone or combined: “nonsteroidal anti-inflammatory drugs,” “dental implants,” “bone healing,” and “osteoprogenitor cells.” The inclusion criteria were the following: randomized, double-blind, placebo-controlled clinical studies, in vivo animal model studies of osseointegration, and in vitro studies of the effects of these agents on osteoprogenitor cells. The literature search revealed 360 references. A total of 31 articles met the inclusion criteria, including 2 clinical trials, 20 animal studies, and 9 osteoprogenitor cell studies. The clinical trials revealed that cyclooxygenase-1 (COX-1) inhibitors did not impair osseointegration. The animal studies showed that any drug that is capable of inhibiting COX-2 may impair the osseointegration process. The in vitro studies showed that COX-2 inhibitors are the most potent depressors of osseointegration at the cellular level. Caution must be taken when selecting COX-2 nonsteroidal anti-inflammatory drugs during the postoperative period.

Comparison of stainless steel and titanium alloy orthodontic miniscrew implants: a mechanical and histologic analysis

INTRODUCTION

The detailed mechanical and histologic properties of stainless steel miniscrew implants used for temporary orthodontic anchorage have not been assessed. Thus, the purpose of this study was to compare them with identically sized titanium alloy miniscrew implants.

METHODS

Forty-eight stainless steel and 48 titanium alloy miniscrew implants were inserted into the tibias of 12 rabbits. Insertion torque and primary stability were recorded. One hundred grams of tensile force was applied between half of the implants in each group, resulting in 4 subgroups of 24 specimens each. Fluorochrome labeling was administered at weeks 4 and 5. When the rabbits were euthanized at 6 weeks, stability and removal torque were measured in half (ie, 12 specimens) of each of the 4 subgroups. Microdamage burden and bone-to-implant contact ratio were quantified in the other 12 specimens in each subgroup. Mixed model analysis of variance was used for statistical analysis.

RESULTS

All implants were stable at insertion and after 6 weeks. The only significant difference was the higher (9%) insertion torque for stainless steel. No significant differences were found between stainless steel and titanium alloy miniscrew implants in microdamage burden and bone-to-implant contact regardless of loading status.

CONCLUSIONS

Stainless steel and titanium alloy miniscrew implants provide the same mechanical stability and similar histologic responses, suggesting that both are suitable for immediate orthodontic clinical loads.

Influence of non-steroidal anti-inflammatory drugs (NSAIDs) on osseointegration of dental implants in rabbit calvaria

AIM

Until recently, adverse effects of non-steroidal anti-inflammatory drugs (NSAIDs) on osseointegration of dental implants were unknown. Hence, this study investigated the short- and long-term effects of a 7-day regimen of parecoxib and diclofenac sodium on osseointegration of dental implants in calvarial bone.

MATERIAL AND METHODS

Eighteen New Zealand White rabbits were randomly allocated into three groups (each n = 6): Control group with no postoperative pain killers (Group A), diclofenac group (Group B) and parecoxib group (Group C). In each animal, one dental implant was placed into the calvarial bone (total n = 18). Three rabbits from each group were sacrificed in Week 4. The other three rabbits from each group were sacrificed in Week 12 postoperatively. The implant together with the calvarial bone and dura mater was harvested and subjected to micro-computed tomography (micro-CT) and histomorphometric analysis.

RESULTS

Quantitative analysis of micro-CT data and histomorphometric data neither revealed any statistically significant (P ≤ 0.05) differences between the three different groups related to osseointegration nor between different time points of observation.

CONCLUSION

In rabbits, a 7-day regimen of appropriate doses of diclofenac sodium and parecoxib did not adversely affect osseointegration of dental implants and bone healing in calvaria, neither short nor long term (12 weeks).

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.

No deleterious effect of low dose methotrexate on titanium implant osseointegration in a rabbit model

OBJECTIVE

To evaluate the effect of low dose methotrexate alone or in combination with glucocorticoid treatment on titanium implant osseointegration.

METHODS

Groups of 6-8 adult New Zealand White rabbits were treated for 18 weeks with saline (control), methotrexate, glucocorticoid, or methotrexate plus glucocorticoid. The animals received a titanium implant in the tibia at week 6. Lumbar spine and tibia bone mineral densities were analyzed before and after treatment. Histomorphometric analysis of bone cortical thickness, total bone area around the implant, and % of bone to implant contact was performed.

RESULTS

After 18 weeks, the change in the bone mineral density in the lumbar spines and tibias in the methotrexate group was comparable to the control group (0.035 vs. 0.055 g/cm² and 0.021 vs. 0.041 g/cm², respectively). In contrast, both the glucocorticoid group and glucocorticoid plus methotrexate group had significant reductions at both sites. Histomorphometric analysis of the tibia in the control and methotrexate groups revealed no significant changes in cortical thickness (133 vs. 126 μm), total bone area around the implant (33 vs. 30%), or bone to implant contact (40 vs. 38%). In contrast, glucocorticoid group had significant reductions compared to controls in tibia cortical thickness (99 vs. 133 μm), total bone area around the implant (24 vs. 33%), and bone to implant contact (27 vs. 40%). Similar reductions were observed in the glucocorticoid plus methotrexate group.

CONCLUSIONS

Our results demonstrate that low dose methotrexate treatment does not affect titanium implant osseointegration, suggesting that this therapy is safe for surgical procedures requiring a titanium implant.

Efficacy of nimesulide versus meloxicam in the control of pain, swelling and trismus following extraction of impacted lower third molar

This study compared the efficacy of nimesulide and meloxicam in the control of pain, swelling and trismus, following the extraction of impacted inferior third molars. Twenty patients with two impacted inferior third molars, in similar positions, were selected. The patients were designated randomly to the meloxicam group (MEL: 7.5mg twice a day for 5 days) or the nimesulide group (NIM: 100mg for 5 days). Following the extractions, swelling was more pronounced in the MEL group than in the NIM group (P<or=0.001). There were no significant differences in pain intensity between the treatment groups (P>0.05). At the 72-h evaluation, reduction was significantly larger in mouth opening in the MEL group compared with the NIM group (P<0.05). In conclusion, pain control was similar in both treatment groups. NIM was more effective than MEL in the control of swelling and trismus following the extraction of impacted lower third molars.

Pathophysiology of cyclooxygenase inhibition in animal models

Cyclooxygenase (COX) catalyzes the conversion of arachidonic acid into prostaglandins (PGs), which play a significant role in health and disease in the gastrointestinal tract (GI) and in the renal, skeletal, and ocular systems. COX-1 is constitutively expressed and found in most normal tissues, whereas COX-2 can be expressed at low levels in normal tissues and is highly induced by pro-inflammatory mediators. Inhibitors of COX activity include: (1) conventional nonselective, nonsteroidal anti-inflammatory drugs (ns-NSAIDs) and (2) COX-2 selective nonsteroidal anti-inflammatory drugs (COX-2 s-NSAIDs). Inhibition of COX-1 often elicits GI toxicity in animals and humans. Therefore, COX-2 s-NSAIDs were developed to provide a selective COX-2 agent, while minimizing the attendant COX-1-mediated GI toxicities. Rats and dogs overpredict COX inhibition for renal effects such as renal handling of electrolytes in humans. COX inhibitors are shown to have both beneficial and detrimental effects, such as on healing of ligament or tendon tears, on the skeletal system in animal models. Certain ophthalmic conditions such as glaucoma and keratitis are associated with increased COX-2 expression, suggesting a potential role in their pathophysiology.