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LEIPZIG, Germany: Using animal models in dental research, especially in periodontal and peri-implant research for testing the performance of dental implants, yields numerous benefits and helps push advances in the field. However, dental professionals are becoming increasingly aware of the disadvantages of animal testing, including questions regarding their ethicality and the applicability of the results to humans. Consequently, the dental scientific community has put a great deal of effort into improving the quality of animal research in dentistry and into developing alternative methods that do not involve animal cruelty—a subject that has been a matter of substantial controversy in dental research.
In today’s society, an increasing number of people are abstaining from animal-derived products, and cosmetic brands are switching to cruelty-free products and campaigns in order to comply with EU regulations against animal testing, to keep up with the global veganism movement and to ensure sales success. Although it is difficult to estimate the total number of people who follow a vegan lifestyle, according to an article published in WTVOX, there are approximately 78 million vegans worldwide. According to the Vegan Society, Google statistics showed a sevenfold increase in the interest in veganism between 2014 and 2019, and the charity noted that Germany is one of the global leaders with regard to vegan product development and launches. According to the same source, the western European country accounted for 15% of global vegan product introductions between July 2017 and June 2018.
It is not clear why, when the general public and the powerful governing bodies are showing a heightened awareness of the issue, and strict legal regulations are in place to govern animal testing, using animals for research purposes is still so pervasive.
Motives behind animal testing in dental research
According to an editorial published in the International Endodontic Journal in 2019, an estimated 115 million animals are used for research purposes worldwide each year, mostly in the US, Japan, China, Australia, France, Canada, the UK, Germany and Brazil. The most common animal species experimented on in dental research are rodents, such as mice and rats, as well as dogs, pigs and monkeys. Using rats and mice in research is favoured by many researchers owing to their cost-effectiveness and high reproducibility as animal models.
According to one study, animal models are particularly used in periodontal and dental implant experiments to test the biocompatibility of novel materials before they are used in humans. Using animal models can also help to better understand the pathogenesis of oral diseases and dento-maxillofacial anomalies. For example, researchers often conduct dental experiments on dogs to determine how well an implant heals in situ and how it affects surrounding tissue. However, dental implant experiments on dogs have recently received substantial focus by the media, and a large number of people from all walks of life—not only animal rights activists—have questioned the ethicality of dental experiments involving dogs.
Animal models may also be used to measure the efficacy of certain medications and to determine the suitability of treatments. However, various studies suggest that there is no single animal model that can be a good predictor of all human conditions, and different specialties in dentistry experiment on different animal models depending on the research objective.
Morality and ethics of animal testing
Some months ago, Dental Tribune International (DTI) had the opportunity to speak with People for the Ethical Treatment of Animals (PETA) about its work concerning animal experiments in dentistry training and research. Biologist Anne Meinert at PETA Deutschland told DTI that, in 2013, PETA India was involved in the decision by the Dental Council of India to end the use of animals in dental training in India nationwide.
“Instead of harming animals, dental colleges in India now use superior and humane non-animal methods, such as cost-efficient computer-assisted learning models, clinical exercises and human patient simulation technology—training techniques that are already used in top medical schools worldwide,” she noted.
PETA is one of the most prominent advocates for animal welfare worldwide. The company aims to expose and address animal suffering in not only laboratories but also the food industry, the clothing trade and the entertainment industry. “PETA’s motto reads, in part, that animals are not ours to experiment on,” Meinert commented.
Meinert believes that conducting dental experiments on animals is outdated and demonstrates resistance to change, despite the scientific and other advantages . More importantly, she says that the results of such experiments are often inaccurate, as they cannot be applied to humans: “Cutting apart and killing sentient beings for dental training and research is cruel and archaic, as well as unscientific given the significant anatomical and physiological differences between species.”
“It is time to shift away from the failed animal experimentation paradigm and to embrace real science”
— Anne Meinert, PETA Deutschland
With the aim of advancing medical and scientific progress, scientists from PETA’s international affiliates have developed the Research Modernisation Deal, which offers a policy guide for the implementation of non-animal methods that are relevant for human health. “It is time to shift away from the failed animal experimentation paradigm and to embrace real science,” Meinert concluded.
Increasing awareness in the dental scientific community
The use of animals for research purposes is governed by explicit and strict guidelines, although they vary greatly around the world. For example, in the US, each research facility using animal species must establish an institutional animal care and use committee to review all experimental protocols involving live, warm-blooded animals, making sure that each animal protocol includes:
(1) a justification for using animals, the number of animals to be used, and the species chosen;
(2) the procedures or drugs to be used to eliminate or minimise pain and discomfort in the animals;
(3) a description of the methods and sources used to search for alternatives to painful procedures; and
(4) a description of the search used to ensure that the experiment does not unnecessarily duplicate previous research.
Even though certain studies need to employ animal models to better understand the mechanisms of human disease as well as to find suitable treatment options, in many fields, such as endodontics, careful consideration must be given as to whether animal studies are appropriate and whether the answers to the research question can be provided in an alternative way. Animal studies are still considered essential for understanding certain issues that could improve human health. However, the Dutch SYstematic Review Center for Laboratory animal Experimentation highlighted that the majority of early clinical trials for novel drugs fail, since the animals experimented on are often used ineffectively or unnecessarily. This can put patients’ health at risk and be a waste of time and money.
To advance the reporting process of research using animals, scientists devised guidelines, including ARRIVE (Animal Research: Reporting of In Vivo Experiments) and the 3Rs (Replacement, Reduction and Refinement), that are intended to help researchers perform more humane animal research and correctly synthesise the research evidence. Additionally, there are useful ethical guidelines available, such as the one published by the American Psychological Association, that offer advice on welfare for animals used in research. Such guidelines support high-quality research by making sure that experimenters follow sound reasoning and that the methods used are appropriate scientifically, technically and humanely.
Discussing animal testing in dentistry with DTI, Prof. Clemens Walter, director of the postgraduate program in periodontics in the centre for dental medicine at the University of Basel in Switzerland, said: “Recently, awareness in the dental scientific community has increased, particularly with respect to periodontal aspects and dental implants. Several publications have critically appraised studies using animals.”
“These uncovered issues that affected the risk of bias, including accuracy of treatment effect estimates and quality of reporting, especially reporting on success parameters for replication in human clinical trials or the methodological quality, that is, power analysis and sample size calculation for animal studies,” Walter explained.
In a bibliometric study, Walter and his fellow researchers aimed to explore changes in the number of published animal studies, the average number of animals experimented on, and the origin of the publications between 1982–83 and 2012–13 in two representative and highly ranked periodontal journals, the Journal of Periodontology and the Journal of Clinical Periodontology. The analysis revealed a twofold increase in the total number of publications that included experiments on animals in the respective journals over the 30-year period.
“Animal experiments do not provide direct evidence relevant to human periodontal or peri-implant diseases”
— Prof. Clemens Walter, University of Basel
Similarly to what Meinert stated, Walter told DTI that there are physiological and evolutionary dissimilarities between humans and animals and that these could affect the validity of animal research: “Animal experiments do not provide direct evidence relevant to human periodontal or peri-implant diseases. To do so, they need to be replicated in human clinical trials,” he concluded.
Search for scientifically proven alternatives to animal testing
Today’s scientific breakthroughs and discoveries have greatly facilitated the transition from traditional methods that rely on animal testing, and some environmental authorities, such as the US Environmental Protection Agency (EPA), have shown great initiative in seeking to reduce animal testing. Since animals are often used in the testing of chemical substances or mixtures thereof, and of the toxicity and biocompatibility of dental implants, for example, Andrew R. Wheeler, then administrator of EPA, in 2019 signed a directive requiring prioritisation of scientifically proven alternatives to animal testing. To achieve this, EPA is promoting the development and timely incorporation of new approach methods (NAMs), strategies that do not require new tests to be performed on vertebrate animals.
“This is a matter of sincere importance to me,” Wheeler told DTI. “Scientific advancements exist today that allow us to better predict potential risks without the use of traditional methods that rely on animal testing.”
“With NAMs, we’re able to evaluate more chemicals across a broader range of potential biological effects in a shorter time frame and with fewer resources while striving for equal or greater results,” he explained. “I look forward to continuing the work we’ve done with our partners toward reducing, replacing and refining animal testing requirements moving forward.”
Alternatives to animal research include using non-animal methods such as in vitro or in silico cell cultures, which is a widely used alternative to animal testing. However, some scientists have suggested that, while using cell cultures reduces the use of laboratory animals, it does not fully reproduce the interaction between organs and tissues. Other methods employ mathematical and computer models. In some cases, healthy or diseased tissue donated by human volunteers can be used in studying human biology and disease.
Although animal studies are subject to strict legislation and ethical considerations, animal research is still a widely accepted practice in many universities and medical schools worldwide. It has contributed greatly to numerous medical advancements and saved the lives of millions of people. Despite their perceived benefits, animal studies can be costly and time-consuming. Mounting evidence also suggests that the results of animal studies are often misleading and unreliable, as they cannot be applied to humans.
Keeping this in mind, it is imperative to continue to make scientific progress and to consider available research options that take animal welfare into consideration in order to reduce animal suffering and further advance research. As stated on Cruelty Free International’s website, “replacing animal tests does not mean putting human patients at risk. It also does not mean halting medical progress. Instead, replacing animal testing will improve the quality as well as the humanness of our science”.