Laboratory tests have limited value for assessing the safety and effectiveness of new therapies in people. Tests must also be conducted on animals that resemble humans, both biologically and developmentally. We generally acknowledge that certain animals may be caught and sold, kept in captivity, or eaten, but using animals to meet human needs is as an area of huge controversy. This chapter gives a broad perspective on the ethical basis for animal experiments, drawing from the modern “common sense” view and several longstanding philosophical theories. Moral status is considered, alongside integrity, autonomy and dignity of animals, and their ability to reason, to form memories, and to experience pleasure or pain. Smaller animals, such as mice, rats and rabbits are essential for proving a basic principle or concept. Larger animals, such as goats, pigs, sheep, dogs and monkeys, are used more sparingly, not least because of the costs involved in their care; they are necessary because of their greater similarity to humans and thus are more relevant to advancing clinical practice. However, conflicts of interest tend to be larger with animals that are more similar to humans. Primate and dogs tend to evoke our compassion more strongly than rodents or animals we commonly eat. The authors provoke thought on this subject through examples in which the interests of humans are weighed up with those of animals in studies of cosmetics, childhood leukemia and dental defects.

Objectives: Immediate-load protocols for edentulous patients are well-documented treatment options, however it is expensive to fabricate a provisional prosthesis that is capable of loading, which must be followed after osteointegration and soft tissue healing by placement of a definitive restoration that fills gaps that appear between the gingiva and prosthesis. The aim of this study was to carry out the OSP technique using a single prosthesis with a metal framework that permits immediate loading, which could be transformed after complete healing to a definitive prosthesis. Methods: Three patients were treated by the OSP technique. Impressions were taken before surgery, with diagnostic set-up for the final restoration. After surgery, further impressions were made of the implants in position and gingival levels, and the master cast was prepared. Titanium cylinders were screwed onto the abutment replicas, and sections of 3.5-mm diameter titanium rods were laser-welded to them. Passive fit of the framework was checked. The prosthesis was intended to achieve optimum aesthetics and occlusion control. Contacts with the cantilever were avoided to prevent implant stress during osteointegration. After validation, the dentures were placed 24 hours after surgery. Master cast models were preserved on the articulator. After osteointegration, gaps between gingiva and prosthesis were recorded by taking mucostatic RIs of the edentulous areas between implants, with injection of silicone directly under the screwed prostheses. Master models were modified by eliminating the stone between the implants, and transitional silicone prostheses were screwed into place. New plaster was poured into the space to modify the crest profile according to the new anatomy, and resin was applied to improve occlusion of the teeth with the entire prosthesis, including the cantilever. The new prostheses were delivered five hours after making impressions. Results: During the observation period of 12–84 months, implant survival rates were 100%. None of the three prostheses were lost, thus the prosthetic survival rate was also 100%. In all three cases, soft tissue levels and the spaces between the prostheses and tissues were stable. Conclusion: The cost of implant treatment is important to patients. The OSP technique with RIs allows a single prosthesis to be used as temporary prosthesis suitable for immediate loading, that can be transformed, after a short time, to a definitive prosthesis that is adapted to the tissue after complete healing. This leads to cost reductions and increased access of patients. The use of RIs decreases chair time and laboratory time, and re-use of the master cast decreases material costs. Further studies are now required with larger sample sizes to better evaluate this promising low-cost option.