Assisted reproductive technology (ART) has been rapidly expanding since the birth of Louise Brown, the first test tube baby, in 1978. Although an increasingly complex array of laboratory skills and procedures have been developed for infertility treatments, the success rate of ART remains low. In an attempt to make ART safer and more efficient, international medical practice is trending towards single embryo transfers and the use of innovative, sophisticated technologies to identify promising gametes and embryos with the highest potential to generate a pregnancy. Laser technology is increasingly being used to accomplish these aims. The application of lasers for ART has been successfully employed in clinical practice for some time now and is continually the subject of investigative research in order to generate new methods to improve operations. Moreover, lasers serve as a powerful tool at the forefront of investigative research in the reproductive sciences, assisting in broadening our understanding of reproductive and developmental biology. Nevertheless, there is a paucity of literature pertaining to the safe standardisation of such laser procedures with evidence at the molecular level. The primary aim of this thesis was to optimise applications of laser technology for clinical ART and research applications in the reproductive sciences. This thesis utilised the mouse embryo model to investigate potential deleterious effects of different laser treatment applications, both by the operator and hardware manufacturer. Safe and unsafe laser operator parameters were elucidated by assessing deleterious effects to the plasma membrane integrity, blastocyst survival rate, DNA fragmentation levels, and changes in gene expression of key developmental genes. The effect of altering the laser hardware to lower the power output was evaluated and it was determined that if a lower power laser is used to deliver a set amount of energy over a longer period of time, a smaller amount of damage is incurred. Work in this thesis also established a new method in which laser technology can be used as a research tool for the reproductive sciences, by creating a novel stimuli-responsive laser-activated nanoparticle delivery system with spatial control and increased efficiency in a mammalian cell model. The field of reproductive science continues to benefit greatly from laser application clinically to improve infertility treatments, and in research, to elucidate mechanisms underlying infertility, with a hope of increasing our understanding and eventually developing new treatment options.

O objetivo deste estudo clinico duplo-cego, randomizado, controlado foi avaliar a resposta pós-operatória de pacientes após cirurgia de extração de terceiros molares inclusos que receberam a irradiação com diferentes protocolos do terapia de fotobiomodulação. Sessenta pacientes foram recrutados de acordo com os critérios de inclusão e exclusão previamente estabelecidos e distribuídos nos 2 grupos experimentais (irradiados) e no grupo placebo (não-irradiado); n=20. Para o grupo 1: ? 660nm, 100mW, 36J/cm2, 1J por ponto, 10 segundos/por ponto (3 pontos intra-oral 6 extra oralmente). Para o grupo 2: ? 808nm, 100mW, 107 J/cm2, 3J por ponto, 30 segundos/por ponto (3 pontos intra-oral 6 extra oralmente). Para todos os grupos os pacientes foram irradiados imediatamente após o procedimento cirúrgico e às 48h. No grupo placebo foi utilizado um laser com o recobrimento da ponta, não permitindo a saída da luz no tecido alvo. Depois da cirurgia todos os participantes foram orientados quanto as recomendações pós-operatórias de rotina. Os pacientes foram instruídos a preencher um diário para avaliação da intensidade da dor pós-operatória em uma escala numérica de dor do máximo ao mínimo após o término do efeito do anestésico, nos períodos de 4, 6, 8, 24 e 48 horas. Para avaliar o processo inflamatório foram usados dois parâmetros: trismo (avaliado mediante a máxima abertura inter-incisiva) e edema (avaliada mediante três medições extra-orais, por meio de uma fita métrica flexível). Para avaliar a deiscência foi realizada uma escala analógica visual e com um medidor de ponta seca com 4 escores (não existe deiscência, leve 5 mm, moderada 10 mm e grave 20 mm ou mais). As variáveis de inflamação e deiscência foram avaliadas em tres momentos diferentes por um observador calibrado no: pré-operatório, às 48 horas e aos 7 dias. Os valores obtidos foram submetidos à análise estatística para determinação da homogeneidade e normalidade da amostra. A partir desta análise foi escolhido o teste estatístico mais adequado para a comparação entre os grupos experimentais realizados. Os resultados revelaram uma correlação positiva entre a irradiação com terapia de fotobiomodulação e as variáveis estudadas. O laser infravermelho apresentou melhores resultados em termos de dor, trismo, edema e deiscência em relação ao laser vermelho, embora os resultados não forneçam dados estatisticamente significativos quando comparados ao grupo placebo. No entanto, os efeitos do laser após a cirurgia de terceiros molares requer mais estudos devido à grande aplicabilidade na área. / The objective of this random controlled double-blind clinical study, is to assess the post-operatory response of patients after a surgery of extraction of included third molars; that received radiation with different protocols of Low Level Laser. Sixty patients were recruited according to the inclusion and exclusion criteria previously established and distributed into two experimental groups (radiated) and into a placebo group (not radiated); n=20. For group 1: ? 660nm, 100mW, 36J/cm2, 1J per point, 10 seconds/per point (3 points intra-oral 6 extra orally). For group 2: ? 808nm, 100mW, 107 J/cm2, 3J per point, 30 seconds/per point (3 points intra-oral 6 extra orally). For all the groups the patients were irradiated immediately after the surgical process and 48 hours after. In the control group a covered tip laser was used; not allowing the exit of the light towards the alveoli tissue. After the surgery all the participants were learnt about the current post operatory recommendations. Patients were instructed to complete a diary to evaluate postoperative pain intensity on a numerical scale of pain from the maximum to the lowest after the end of the anesthetic effect, in the periods of 4, 6, 8, 24 and 48 hours. To assess the inflamatory process, two parameters were used: Trismus (a measure of the maximum inter-incisor separation) and edema (assessed by three extra-oral measurements done with a flexible measuring tape). To assess the dehiscence, an analogue scale with 4 data fields was used (nonexistent dehiscence, slight 5 mm, moderate 10 mm and severe 20 mm or more). The variables of inflamation and dehiscence were assessed in three different moments by a qualified observer in: pre-operatory, after 48 hours and after 7 days. The values obtained were subjected to a statistic analysis for determination of homogeneity and normality of the sample. From this analysis, the most suitable statistic test was chosen for comparison between experimental groups. The outcome showed a positive correlation between photobiomodulation therapy and the studied variables. The infrared laser showed better results in terms of pain, trismus, edema and dehiscence in comparison to the red laser, although the results did not provide meaningful statistic data when comparing to the control group. Nevertheless, the effects of laser after a surgery of third molars require further studies due to the wide application in the area.