Cargas oclusais excessivas podem promover tensões exageradas às estruturas de implantes/pilares/próteses, resultando em deformação, desadaptação ou mesmo fratura dos componentes e do próprio implante. Além disso, tais sobrecargas podem gerar necrose por compressão e perda óssea peri-implantar e, ainda, a ocorrência de microdeslocamentos na interface de conexão implante-pilar (I-P) ocasionando a formação de fendas propícias à colonização bacteriana, o que pode levar ao desenvolvimento de peri-implantite, contribuindo para o insucesso do conjunto. O presente estudo objetivou avaliar, por meio de uma técnica já amplamente utilizada na Engenharia e na Física a Interferometria Eletrônica por Padrões de Speckle (ESPI) as deformações a nível do colar de implantes com conexão cônica interna (cone Morse) de diferentes diâmetros (Kopp 4,3/5,5 mm e Neodent 3,5/5,0 mm), sob dois tipos (cêntrica e excêntrica) e intensidades (50 N e 100 N) de cargas, similares as quais os implantes ficam expostos durante a função mastigatória. Testou-se a hipótese de que a deformação do colar do implante seria inversamente proporcional ao diâmetro do implante. Além disso, discutiu-se vantagens e limitações da técnica ESPI frente a outros métodos comumente utilizados na avaliação de tensões. As maiores deformações foram sempre associadas às cargas excêntricas, com exceção do G1-Kopp. A maior deformação ocorreu no G1-Neodent sob carga excêntrica de 100 N e a menor, no G2-Neodent sob carga cêntrica de 50 N. A técnica ESPI mostrou-se altamente sensível e reprodutível para avaliar deformações a nivel do colar de implantes sendo possível confirmar a hipótese inicial, visto que a maior deformação esteve sempre associada aos implantes de menor diâmetro, em ambos os sistemas de implante pesquisados. / Occlusal overloading may promote excessive stresses to the implants/abutments/prosthesis, resulting in deformation, misfit or fracture of the components, until the implants. Futhermore, strains of the implant-abutment connection can cause the formation of microgaps propitious to bacterial colonization, which leads to the development of peri-implant sites, leading to the failure of the rehabilitation. This study aimed to evaluate, by a technique widely used in the engineering and physics Electronic Speckle Pattern Interferometry (ESPI) the strains related to the implant collar with internal tappered connection (Morse taper) with different diameters (Kopp 4.3/5.5 mm and Neodent 3,5/5,0 mm), under two types (centric and eccentric) and intensities (50 N and 100 N) of loads, similar which implants are exposed during masticatory function. We tested the hypothesis that the strains of the implants collar would be inversely proportional to the diameter of the implant. In addition, the survey discussed the advantages and limitations of the ESPI technique over other methods commonly used to assess strains. The largest strain was always associated with eccentric loads, except for G1-Kopp. The largest strain occurred in the G1-Neodent under the eccentric loads of 100 N and the lowest in the G2-Neodent under the centric loads of 50 N. The ESPI technique was a highly sensitive and reproducible to evaluate the strains at the level of the collar of implants being possible to confirm the initial hypothesis, since most strains was always associated with narrower-diameter implants in both implant systems studied.

Chronic patellar tendinopathy is a degenerative tendon disorder characterized by chronic activity-related, anterior knee pain associated with localized tenderness, swelling and impaired performance, which is a common clinical problem in athletes. The pathogenesis of patellar tendinopathy is still largely unknown, although tendon overuse is the most commonly suggested etiological factor, and treatment is usually symptomatic. / Histopathologically, the predominant feature of patellar tendinopathy is tendinosis, which is characterized by progressive tissue degeneration with a failed healing response and the absence of inflammatory cells. Hypercellularity with non-tenocyte phenotype cells and tissue metaplasia, including hyaline metaplasia, fibrocartilaginous metaplasia and bony metaplasia were observed in clinical patellar tendinopathy samples. The degeneration of patellar tendon in patellar tendinopathy is an active cell-mediated process rather than a passive degenerative process. Using a patellar tendinopathy animal model, we observed the presence of chondrocytic and osteoblastic phenotype / markers in patellar tendinopathy samples with or without ossification, which was consistent with the findings in clinical samples. Interestingly, chondrocyte makers were expressed by healing tendon cells at week 2 which became round prior to their expression in the chondrocyte-like cells at week 4. This leads us to speculate that erroneous differentiation of tendon-derived stem cells (TDSCs) identified recently in tendon tissues by our group, to chondrocyte / osteoblasts, due to alteration of mechanical and biological microenvironment during overuse, may lead to the ectopic chondro-ossification and failed healing in patellar tendinopathy. Osteo-chondrogenic BMPs, such as BMP-2, BMP-4 and BMP-7 might be possible factors regulating the osteo-chondrogenic differentiation of TDSCs in the pathogenesis of patellar tendinopathy. / In conclusion, our results have provided new insights about the pathological mechanisms of patellar tendinopathy involving the resident stem cells, osteo-chondrogenic BMPs and mechanical overloading. Erroneous differentiation of TDSCs to chondrocytes / osteoblasts due to ectopic osteo-chondrogenic BMP-2 expression, which were induced by repetitive tensile loading stimulation, might account for the chondro-ossification and failed healing in patellar tendinopathy. Re-directing of stem cells for tenogenic differentiation by blocking the ectopic expression of osteo-chondrogenic BMPs may help to promote tendon healing in patellar tendinoapthy. / In this study, we hypothesized that (1) TDSCs isolated from pathological patellar tendon of the CI model will exhibit higher osteogenic and chondrogenic differentiation potential but lower proliferative capacity compared to TDSCs isolated from healthy patellar tendon. Rat pathological tendon in our collagenase-induced failed healing animal model will harbor more TDSCs compared to healthy patellar tendon. (2) Osteo-chondrogenic BMPs, such as BMP-2, BMP-4, and BMP-7, will be expressed ectopically in both preclinical and clinical samples of patellar tendinopathy. (3) BMP-2 will promote osteo-chondrogenic differentiation and inhibit tenogenic differentiation of TDSCs in vitro. (4) Repetitive tensile loading will increase the expression of BMP-2 in TDSCs in vitro. / Our results showed that TDSCs isolated from the collagenase-induced tendinopathic patellar tendon of the animal model exhibited higher osteogenic/chondrogenic differentiation potential as well as lower proliferative capacity, supporting that there might be some defects in the TDSCs from the animal model, which might undergo osteo-chondrogenic differentiation and hence reduced the pool of TDSCs for tendon repair in the development of patellar tendinopathy. The higher clonogenicity and increased yield of TDSCs in tendinopathic patellar tendon might be caused by a compensation for the impaired differentiation potential and proliferative capacity of TDSCs. The histopathological features of our clinical patellar tendinopathy were characterized by tissue degeneration. Non-tenocyte phenotype cells and tissue metaplasia, such as chondrocyte-like cells and endochondral ossification were also observed. We observed the ectopic expression of osteo-chondrogenic BMP-2, BMP-4 and BMP-7 in both our animal model and clinical samples of patellar tendinopathy, which might trigger the erroneous differentiation of TDSCs to non-tenocytes. Indeed, we further showed that BMP-2 could promote the osteo-chondrogenic and inhibit tenogenic differentiation of TDSCs in vitro, which might provide a possible explanation for ectopic chondro-ossification and failed healing in patellar tendinopathy. In addition, our results also showed that in vitro repetitive cyclic tensile loading could increase the expression of BMP-2 in TDSCs, which might provide a possible explanation for the ectopic expression of BMP-2 in patellar tendinopathy. / This study aimed to compare the osteogenic / chondrogenic differentiation potential, proliferative capacity and yield of TDSCs isolated from rat healthy patellar tendon and pathological tendon in our collagenase-induced failed tendon healing animal model of patellar tendinopathy in vitro. The histopathological characteristics of our clinical patellar tendinopathy with or without ossification were examined. The ectopic expression of BMP-2, BMP-4, and BMP-7 in both human and rat samples of patellar tendinopathy was also examined. The effects of BMP-2 on the osteogenic, chondrogenic and tenogenic differentiation of TDSCs was further investigated in vitro. The effect of repetitive tensile loading on the expression of BMP-2 in TDSCs was studied in vitro. / Rui, Yunfeng. / Advisers: Kai Ming Chan; Po Yee Lui. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 172-193). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Airway remodeling in asthma includes alterations in extracellular matrix and airway smooth muscle (ASM) mass. For this study, ASM cells were obtained from rats that were challenged with ovalbumin (OVA) or saline (SAL) as control. OVA and SAL cells were seeded on plastic control (PC) or on plates coated with decorin or biglycan. OVA cell number was significantly increased versus SAL cells, for cells seeded on PC (48 h). A significant decrease in cell number was observed for both OVA and SAL cells seeded on decorin compared to PC cells (48 h). OVA cells, however, showed a more modest reduction in cell number. Furthermore, biglycan decreased SAL cell number only. Compared to no strain (NS), mechanical strain (S) reduced cell number for OVA and SAL cells on all matrices. In addition, S up-regulated expression of beta 1-integrin relative to NS controls. Results suggest an ability of ASM cells to be modulated by matrix and mechanical stimulation.

Orientador: Luiz Felipe Valandro Soares / Coorientadora: Renata Marques de Melo Marinho / Banca: Marco Antonio Bottino / Banca: Paulo Francisco César / Banca: Estevam Augusto Bonfante / Banca: Lilian Costa Anami / Resumo: O objetivo deste estudo foi avaliar os efeitos de duas técnicas de gradação da zircônia no limite de fadiga de próteses parciais fixas (PPFs) de 03 elementos. Blocos pré-sinterizados de 3Y-TZP (zircônia policristalina parcialmente estabilizada por 3% mol de ítria) foram fresados para obter 69 PPFs, que foram divididas em 3 grupos (n = 23). O grupo controle (CTL) foi sinterizado e glazeado odedecendo os parâmetros usuais. Nos dois grupos experimentais as PPFs receberam sílica/vidro antes da sinterização. O grupo sílica sol-gel (SSG) foi graduado pela rota de processamento sol-gel, enquanto o grupo vidro-zircônia-vidro (GZG) foi graduado pela técnica de suspensão (slurry). Os grupos graduados não receberam a camada de glaze após a sinterização. Todas as PPFs foram cimentadas nos pilares de compósito com cimento resinoso de dupla polimerização, incluídas em poliuretano e armazenadas em água por cinco dias. A carga inicial do teste de fadiga foi calculada com base nos resultados do ensaio monotônico de três amostras de cada grupo. Para determinar o limite de fadiga 20 amostras de cada grupo foram submetidas ao método da escada ou staircase (100.000 ciclos/5 Hz). Os limites de fadiga (em Newton) foram: CTL = 1607,27; SSG = 1824,31; GZG = 2006,57 e o teste de Dixon e Mood indicou diferença estatística entre os grupos (intervalo de confiança de 95%). As infiltrações de sílica e vidro no corpo da zircônia, por dois diferentes métodos de gradação, aumentaram o limite de fadiga de PPFs... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the effects of two grading zirconia techniques on the fatigue limit of 3-unit fixed dental prostheses (FDPs). Presintered blocks of 3YTZP (3 mol% yttria-stabilized tetragonal zirconia polycrystal) were milled to obtain sixty-nine 3-unit FDPs, which were divided into three groups (n = 23). The control group (CTL) was sintered and glazed following the usual parameters. In the two experimental groups presintered FDPs received silica/glass before sintering. Silica sol-gel group (SSG) was graded by the sol-gel processing route, while the glasszirconia-glass group (GZG) was graded by a slurry technique. Graded groups did not receive a glaze layer after sintering. All FDPs were then luted with a dual-curing resin cement on composite abutments, embedded in polyurethane and stored in water for five days. The initial load of the fatigue test was calculated based on the results of the monotonic testing applied on three specimens of each group. To determine the fatigue limit, 20 samples of each group were subjected to staircase testing (100,000 cycles/5 Hz). The fatigue limits (in Newtons) were CT = 1607.27, SSG = 1824.31, and GZG = 2006.57, and the Dixon and Mood test indicated statistically significant differences among groups (95% confidence interval). The infiltration of silica and glass on zirconia bulk, by two different grading methods, increased the fatigue limits of monolithic zirconia FDPs / Doutor

Cargas oclusais excessivas podem promover tensões exageradas às estruturas de implantes/pilares/próteses, resultando em deformação, desadaptação ou mesmo fratura dos componentes e do próprio implante. Além disso, tais sobrecargas podem gerar necrose por compressão e perda óssea peri-implantar e, ainda, a ocorrência de microdeslocamentos na interface de conexão implante-pilar (I-P) ocasionando a formação de fendas propícias à colonização bacteriana, o que pode levar ao desenvolvimento de peri-implantite, contribuindo para o insucesso do conjunto. O presente estudo objetivou avaliar, por meio de uma técnica já amplamente utilizada na Engenharia e na Física a Interferometria Eletrônica por Padrões de Speckle (ESPI) as deformações a nível do colar de implantes com conexão cônica interna (cone Morse) de diferentes diâmetros (Kopp 4,3/5,5 mm e Neodent 3,5/5,0 mm), sob dois tipos (cêntrica e excêntrica) e intensidades (50 N e 100 N) de cargas, similares as quais os implantes ficam expostos durante a função mastigatória. Testou-se a hipótese de que a deformação do colar do implante seria inversamente proporcional ao diâmetro do implante. Além disso, discutiu-se vantagens e limitações da técnica ESPI frente a outros métodos comumente utilizados na avaliação de tensões. As maiores deformações foram sempre associadas às cargas excêntricas, com exceção do G1-Kopp. A maior deformação ocorreu no G1-Neodent sob carga excêntrica de 100 N e a menor, no G2-Neodent sob carga cêntrica de 50 N. A técnica ESPI mostrou-se altamente sensível e reprodutível para avaliar deformações a nivel do colar de implantes sendo possível confirmar a hipótese inicial, visto que a maior deformação esteve sempre associada aos implantes de menor diâmetro, em ambos os sistemas de implante pesquisados. / Occlusal overloading may promote excessive stresses to the implants/abutments/prosthesis, resulting in deformation, misfit or fracture of the components, until the implants. Futhermore, strains of the implant-abutment connection can cause the formation of microgaps propitious to bacterial colonization, which leads to the development of peri-implant sites, leading to the failure of the rehabilitation. This study aimed to evaluate, by a technique widely used in the engineering and physics Electronic Speckle Pattern Interferometry (ESPI) the strains related to the implant collar with internal tappered connection (Morse taper) with different diameters (Kopp 4.3/5.5 mm and Neodent 3,5/5,0 mm), under two types (centric and eccentric) and intensities (50 N and 100 N) of loads, similar which implants are exposed during masticatory function. We tested the hypothesis that the strains of the implants collar would be inversely proportional to the diameter of the implant. In addition, the survey discussed the advantages and limitations of the ESPI technique over other methods commonly used to assess strains. The largest strain was always associated with eccentric loads, except for G1-Kopp. The largest strain occurred in the G1-Neodent under the eccentric loads of 100 N and the lowest in the G2-Neodent under the centric loads of 50 N. The ESPI technique was a highly sensitive and reproducible to evaluate the strains at the level of the collar of implants being possible to confirm the initial hypothesis, since most strains was always associated with narrower-diameter implants in both implant systems studied.

Orientador: Guilherme Elias Pessanha Henriques / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-19T17:02:54Z (GMT). No. of bitstreams: 1 Tramontino-Mesquita_VanessaSilva_D.pdf: 1263598 bytes, checksum: 21599a6e0153542032add63750d48770 (MD5) Previous issue date: 2012 / Resumo: O objetivo neste estudo foi avaliar a distribuição das tensões geradas aos implantes modificados, por meio de análise extensométrica e força de destorque dos parafusos de retenção protética, de acordo com o tipo de metal da infraestrutura (Titânio comercialmente puro - Ti c.p ou Cobalto-Cromo - Co-Cr) e presença ou ausência de desajuste vertical padronizado. Um modelo metálico foi confeccionado, simulando uma mandíbula edêntula. Cinco análogos de pilares multi-unit foram fixados ao modelo metálico, posicionados de forma a reter uma prótese fixa total sobre implantes. Dez infraestruturas em titânio c.p. e 10 infraestruturas em Co-Cr foram obtidas através de fundição em monobloco. Cada infraestrutura originou dois modelos para mensuração, um adaptado e outro desadaptado em relação aos análogos. Para a obtenção dos modelos desadaptados, anéis metálicos de espessuras conhecidas (100, 200 e 300 ?m) foram posicionados entre a infraestrutura e seus análogos correspondentes. As infraestruturas foram distribuídas entre os grupos de tratamento (n=10): G1: Titânio adaptada; G2: Titânio desadaptada; G3: Co-Cr adaptada; G4: Co-Cr desadaptada. Em todos os casos, as infraestruturas foram fixadas aos análogos com torque de 10 N.cm com torquímetro digital. A força de destorque foi avaliada com torquímetro digital e o desajuste vertical, avaliado por meio de microscópio óptico (aumento de 120x), pelo teste do parafuso único. Extensometria foi utilizada para determinar as tensões geradas às fixações. As médias e desvio padrão de desajuste (?m) foram G1: 36,63 (15,84), G2: 174,45 (33,64), G3: 43,25 (14,06) e G4: 173,18 (24,45) (ANOVA e Tukey; alfa=5%), havendo diferença entre adaptados e desajuste, porém sem diferença entre Ti e Co-Cr. Não houve diferença entre os metais para tensão induzida aos implantes, mas maiores valores de desajuste promoveram maior tensão (ANOVA e Tukey; alfa=5%). Houve forte correlação positiva entre desajuste e tensão (Coeficiente de Correlação de Pearson, r=0,7475 e p<0,0001) e moderada correlação positiva entre desajuste e destorque (Coeficiente de Correlação de Pearson, r=0,3357 e p=0,0341). Para tensão e destorque, houve fraca correlação positiva (Coeficiente de Correlação de Pearson, r=0,2146 e p=0,1834). Pode-se concluir que próteses desadaptadas, independentemente do tipo de liga, promovem aumento nos valores de tensão aos implantes, mas não influenciam na força de destorque de parafusos protéticos / Abstract: This study evaluated stress induced on the implants using strain gauges analysis, and detorque loads of titanium prosthetic screws according to the type of the framework metal (c.p. Titanium or Cobalt-Chromium) and to the presence or absence of misfit. A metallic master model was fabricated, simulating an edentulous patient mandible. Five multi-unit abutment analogues were fixed on the master model, placed as though they would support a total fixed prosthesis. Ten c.p. titanium and 10 cobalt-chromium frameworks were obtained by 1-piece casting. Each framework created 2 measurement models, one passive fitted and the other misfitted to the analogues. To obtain the misfitted measurement models, metallic rings with known thickness (100, 200 and 300 ?m) were positioned between the framework and its analogues. Frameworks were distributed to treatment groups (n=10): G1: Titanium Passive Fit; G2: Titanium Misfit; G3: Cobalt-Chromium Passive Fit; and G4: Cobalt-Chromium Misfit. All infrastructures were screwed to their analogues using a digital torquimeter, with a torque of 10 N.cm. Detorque was assessed with a digital torquimeter, and misfit was evaluated by an optical microscope (120 X) according to the one-screw test. Strain gauges were used to determine stress generated on the fixations. Misfit mean values (?m) were G1: 36.63 (15.84), G2: 174.45 (33.64), G3: 43.25 (14.06) e G4: 173.18 (24.45), presenting difference between passive fit and misfit however no difference was found between the metals (ANOVA and Tukey; alfa=5%). There was no difference between materials for stress induced upon implants, but a higher level of misfit promoted higher values of stress (ANOVA and Tukey; alfa=5%). There was a strong positive correlation between fit and stress (Pearson's Correlation Coefficient, r=0.7475 and p<0.0001), and a moderate correlation between fit and detorque (Pearson's Correlation Coefficient, r=0.3357 and p=0.0341). For stress and detorque, there was a weak positive correlation (Pearson's Correlation Coefficient, r=0.2146 and p=0.1834). Misfitted prostheses, regardless of the metal type, promote high rates of stress to the implants, but do not influence the detorque of prosthetic screws / Doutorado / Protese Dental / Doutor em Clínica Odontológica

Aseptic loosening of the components is probably the most common long-term complication resulting in failure of Total Hip Arthroplasty. The mechanical behaviour of bone under load is one of the contributory causes of loosening encountered at the prosthesis/cement/bone interface. The present study dealt with a series of invitro experiments conducted on epoxy resin models of human hemi-pelves with different commercially available acetabular components implanted in them. These are used for the construction of simplified models of the artificial hip joint (three-dimensional) and of the prosthesis/cement/bone acetabular interface (two-dimensional). Loading conditions for the models included tensioning of the simulated abductor muscles for the hemi-pelvic and femoral loading for the prosthesis/cement/bone interface study. The experimental method employed was real-time holographic interferometry, a stress analysis technique recently used in the biomechanical field, which permitted whole-field simultaneously inspection of deformation patterns. The holographic interferograms were interpreted in a qualitative rather than a quantitative manner. The models do not exactly represent the in-vivo situation. Since this study identified high stresses both in the hip bone as well as in the interface (prosthesis/bone) it is suggested that these stresses are implicated in the mechanical pathogenesis of loosening. The observed changes in stress levels detected in our models could serve as a guide for future designs of acetabular prostheses as well as guide a in surgical techniques.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Objectives: A new technology has been introduced into the field of dental resin composites that professes to enhance light-curing efficiency. Rapid amplified photopolymerization (RAP) initiator technology has not yet been fully compared with resin composites with conventional initiators such as camphorquinone (CQ). The purpose of this study was to compare and contrast the effects of this novel technology (RAP) on properties of two light-cured resin composites. Flowable (EFQ) and microfilled (ESQ) experimental composites were fabricated and supplied from Tokuyama Dental with (w/RAP) and without RAP (w/o RAP). The flexural strength (MPa) and flexural modulus (MPa) were obtained using a three-point bending apparatus (Sintech Renew 1123, Instron Engineering Corp., Canton, MA). Polymerization stress curves were created using a tensometer (American Dental Association Health Foundation, NIST, Gaithersburg, MD) which were then used to calculate the maximum stress rate. Finally, the degree of conversion was measured using infrared spectroscopy (Jassco FT-IR spectrometer, Model: 4100, Jasco Corporation, Tokyo, Japan). When evaluating the flexural strength, the peak stress for EFQ w/RAP was significantly higher than EFQ w/o RAP (p = 0.0001). This was statistically not significant for the ESQ group, even though ESQ w/RAP did have a higher peak stress then ESQ w/o RAP (p = 0.28). The interaction between resin type and RAP was not significant when evaluating the flexural modulus (p = 0.21). Formulations with RAP had a significantly higher flexural modulus then w/o RAP (p = 0.0001). Experimental resins with RAP had significantly higher maximum stress rates than those w/o RAP when evaluating polymerization stress (p = 0.0001). Finally, groups w/ RAP appeared to have a higher degree of conversion than groups without (p = 0.0057). This study showed that the experimental composites with RAP had greater mechanical properties than those without. Unfortunately, the increase in polymerization stress causes concern clinically due to the chance of leakage at the restoration/tooth interface. One of the main potential disadvantages of this new RAP technology is an increase in the polymerization stress. Deciding if this amount of polymerization stress is clinically acceptable is yet to be accomplished.

PURPOSE: To explore the use of crystal inter-planar d-spacings and slip-plane interaction energies for predicting and characterising mechanical properties of crystalline solids. METHODS: Potential relationships were evaluated between mechanical properties and inter-planar d-spacing, inter-planar interaction energy, and dispersive surface energy as determined using inverse gas chromatography (IGC) for a set of pharmaceutical materials. Inter-planar interaction energies were determined by molecular modelling. RESULTS: General trends were observed between mechanical properties and the largest inter-planar d-spacing, inter-planar interaction energies, and IGC dispersive surface energy. A number of materials showed significant deviations from general trends. Weak correlations and outliers were rationalised. CONCLUSIONS: Results suggest that the highest d-spacing of a material could serve as a first-order indicator for ranking mechanical behaviour of pharmaceutical powders, but with some reservation. Inter-planar interaction energy normalised for surface area shows only a weak link with mechanical properties and does not appear to capture essential physics of deformation. A novel framework linking mechanical properties of crystals to the distinct quantities, slip-plane energy barrier and inter-planar interaction (detachment) energy is proposed.