Impacto da deficiencia de estrogeno e suas terapias sobre o tecido osseo ao redor de implantes de titanio e na periodontite induzida em ratas ovariectomizadas

Orientador: Francisco Humberto Nociti JuniorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Osteoporose e osteopenia são doenças osteometabólicas caracterizadas por uma diminuição progressiva de massa óssea gerada pela deficiência de estrógeno na pós-menopausa ou pela ovariectomia. Diversas terapias têm sido propostas para o tratamento destas patologias como, por exemplo, a terapia de reposição estrogênica, os bisfosfonatos e a calcitonina. Assim como os ossos longos, a doença parece atingir os ossos orais, o que poderia afetar o sucesso de implantes dentais e a progressão da doença periodontal. Os objetivos deste trabalho foram avaliar, através de análise histométrica: 1 - a influência da deficiência de estrógeno induzida (DEI) sobre o tecido ósseo ao redor de implantes de titânio e na perda óssea proveniente da periodontite induzida (PI) em ratas ovariectomizadas (OVX); 2 - a influência da terapia de reposição estrogênica (TRE), da calcitonina (CT) e do alendronato (ALD) sobre o tecido ósseo ao redor de implantes de titânio e na perda óssea proveniente da PI em OVX; 3 - o efeito residual da TRE e do ALD; 4 - o efeito da deficiência de estrógeno relacionada à idade (DERI) , comparativamente a DEI, sobre o tecido ósseo ao redor de implantes de titânio. Os resultados demonstraram um efeito negativo da DEI no tecido ósseo preexistente e neoformado ao redor dos implantes de titânio e na perda óssea decorrente da PI. A TRE contínua e o ALD (contínuo-C e interrompido-I) demonstraram-se capazes de prevenir a influência negativa da deficiência de estrógeno endógeno ao redor dos implantes. Somente o ALD (C/I) apresentou efeito positivo na prevenção da progressão da perda óssea decorrente da PI. A DERI apresentou impacto negativo apenas no osso preexistente ao redor dos implantes de titânioAbstract: Osteoporosis and osteopenia has been defined as systemic skeletal diseases characterized by gradual loss of bone tissue. The most common cause of osteoporosis is the decrease of estrogen level, in menopause or ovariectomy. Estrogen replacement, calcitonin and bisphosphonates therapies have been considered for preventing and treating osteoporosis. Significant relationships have been reported between oral bone and skeletal bone mass in postmenopausal women with osteoporosis. Osteoporosis could, therefore, be considered as a risk factor for dental implants and periodontitis progression. The purpose of this study was, by histometric analysis, to evaluate: 1 - the influence of an induced estrogen-deficient (IED) state on bone around titanium implants placed in ovariectomized rats (OVX) and on bone loss resulting from an experimental periodontitis (EP); 2 - the impact of estrogen (E), calcitonin (CT) and alendronate (ALD) administrations on bone density and healing around titanium implants and on bone loss resulting from an EP; 3 - whether ALD and E therapies would provide a residual effect; 4 - the influence of age-related (ARED) and surgically IED, comparatively, on bone around titanium implants inserted in rats. The results demonstrated that IED affects bone healing and bone density around titanium implants and bone loss resulting from EP. Continuous (C) E and interrupted (I) and C-ALD may prevent the negative influence of IED on bone around titanium implants. Only ALD (C/I) may protect against the impact of IED on alveolar bone loss resulting from EP. ARED mainly affects pre-existing bone while IED more significantly affects both newly formed and pre-existing boneDoutoradoPeriodontiaDoutor em Clínica Odontológic

Efeito do estrogeno e da calcitonina sobre o reparo e densidade ossea ao redor de implantes de titanio inseridos em ratas ovariectomizadas

Orientador : Francisco Humberto Nociti JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: o objetivo desse estudo foi avaliar a influência do estrógeno (E) e da calcitonina (CT) sobre o reparo e densidade óssea ao redor de implantes inseridos em ratas ovariectomizadas (OVX). Cinqüenta e oito animais foram divididos aleatoriamente em quatro grupos experimentais: Grupo 1 (n=15): ovariectomia simulada; Grupo 2 (n=15): ovariectomia; Grupo 3 (n=14): OVX e administração subcutânea de CT, 4 dias por semana (16 IU/Kg), um dia após OVX durante todo período experimental; Grupo 4 (n=14): OVX e administração diária de 1713 estradiol (20Jl9/Kg) um dia após OVX durante todo período experimental. Vinte e um dias após a ovariectomia bilateral, cada animal recebeu um implante de titânio rosqueável por tíbia. Após sessenta dias da colocação dos implantes os animais foram sacrificados e obtidas secçóes não-descalcificadas. Os parâmetros histométricos analisados foram: densidade óssea (DO) numa região de 500 Jlm lateral ao implante, contato direto osso-implante (CD) e área óssea dentro das roscas (AO). Os resultados foram obtidos e avaliados separadamente na região cortical (zona A) e medular (zona B). Na zona A, a análise intergrupo não demonstrou diferenças estatisticamente significantes para o CD e DO (P>0.05). Em contraste, o grupo 4 demonstrou maior área óssea que os grupos 2 e 3 (P<0.05). Resultados obtidos da zona B revelaram que o estrógeno anulou o efeito negativo da ovariectomia na DO, CD e AO (P<O.05), enquanto a calcitonina não apresentou o mesmo efeito (P>0.05). Dentro dos limites desse estudo, conclui-se que a administração diária de estrógeno pode prevenir a influência negativa da deficiência do estrógeno endógeno no reparo e densidade óssea ao redor de implantes de titânioAbstract: This study evaluated whether estrogen (E) and calcitonin (CT) administration could influence bone healing and bone density around implants placed in ovariectomized rats (OVX). Twenty-one days betore implant placement, bilateral ovariectomies were performed trom a dorsal approach. One screw-shaped titanium implant was placed bilaterally. The animais were assigned to one of the tollowing groups: Group 1 (n=15): sham surgeries; Group 2 (n=15): OVX rats; Group 3 (n=14): OVX rats subcutaneously administered with calcitonin (CT) 4 days/week (16 IU/Kg); Group 4 (n=14): OVX rats subcutaneously administered with 1713 estradiol daily (20Jlg/Kg). After sixty days, the animais were sacrificed and undecalcified sections obtained. Bone density (8D) (the proportion of mineralized bone in a 500 Jlm-wide zone lateral to the implant), bone-to-implant contact (B/C) and bone area (BA) around the implants were obtained and arranged separately for the cortical (Zone A) and cancellous(Zone B). In Zone A, intergroup analysis revealed no significant difference regarding BIC and BD (P>0.05). In contrast, the group 4 presented a greater bone area than groups 2 and 3 (PO.05). Therefore, E-therapy may prevent the influence that endogenous estrogen deficiency exerts on bone healing and bane density around titanium implantsMestradoPeriodontiaMestre em Clínica Odontológic

Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs

Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole) and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of &#946;-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections

Effect Of Estrogen Replacement And Calcitonin Therapies On Bone Around Titanium Implants Placed In Ovariectomized Rats: A Histometric Study.

The aim of the present study was to evaluate whether hormone replacement therapy (HRT) and calcitonin (CT) administration could influence bone healing around implants placed in ovariectomized (OVX) rats. One screw-type titanium implant was placed bilaterally in OVX rats. The animals were assigned to one of the following groups: group 1 (n = 15), sham surgeries; group 2 (n = 15), OVX rats; group 3 (n = 14), OVX rats administered CT 4 days/week (16 IU/kg); group 4 (n = 14), OVX rats administered 17beta estradiol daily (20 microg/kg). After 60 days, the animals were sacrificed and undecalcified sections obtained. Bone-to-implant contact (BIC) and bone area (BA) around the implants were determined separately for the cortical (zone A) and cancellous (zone B) bone areas. In zone A, intergroup analysis did not reveal a significant difference regarding BIC. In contrast, the HRT group (group 4) presented greater BA than groups 2 and 3 (P .05). It was the first study to evaluate and demonstrate the impact of HRT and CT on bone around titanium implants in an estrogen-deficient model. Within the limits of the present study, it may be concluded that HRT may prevent the influence that estrogen deficiency exerts on bone healing around titanium implants.17786-9

Bacterial Adhesion on Smooth and Rough Titanium Surfaces After Treatment With Different Instruments

Background: Newly formed biofilm after implant debridement may challenge the long-term stability of peri-implant therapy. This in vitro study aimed to assess the roughness and adherence of Streptococcus sanguinis after treatment of smooth and rough titanium surfaces with an erbium-doped: yttrium, aluminum, and garnet (Er:YAG) laser, metal and plastic curets, and an air-powder abrasive system. Methods: Forty titanium disks with smooth-machined surfaces and 40 with sand-blasted and acid-etched surfaces were divided into the following treatment groups: Er:YAG laser; plastic curet; metal curet, and air-powder abrasive system. The surface roughness (roughness average [Raj) before and after treatments was determined using a profilometer. S. sanguinis (American Type Culture Collection 10556) was grown on treated and untreated specimens, and the amounts of retained bacteria on the surfaces were measured by the culture method. Rough and smooth surfaces with and without a suspension of S. sanguinis were also analyzed using scanning electron microscopy (SEM). Results: For smooth surfaces, the roughest surfaces were produced by metal curets (repeated - measures analysis of variance [ANOVA] and Tukey test; P<0.05). The rough-surface profile was not altered by any of the treatments (repeated-measures ANOVA; P>0.05). Rough surfaces treated with metal curets and air-powder abrasion showed the lowest level of bacteria] adhesion (two-way ANOVA and Tukey test; P<0.05). SEM analysis revealed distinct surface profiles produced by all devices. Conclusions: Metal curets are not recommended for smooth titanium surface debridement due to severe texture alteration. Rough surfaces treated with a metal curet and the air-powder abrasive system were less susceptible to bacterial adhesion, probably due to texture modification and the presence of abrasive deposits. J Periodontol 2009;80: 1824-1832.FAPESP Sao Paulo State Research Support Foundation[97/10823-0]FAPESP Sao Paulo State Research Support Foundation[05/02561-3]FAPESP Sao Paulo State Research Support Foundation[04/01175-0