Made available in DSpace on 2015-05-14T13:21:08Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4018152 bytes, checksum: 7560bbf38d03b95122bd3a1ec4fe0fec (MD5) Previous issue date: 2011-09-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The main application of calcium phosphates is as biomaterials, which are used as graft or bone implants. The preparation of mesoporous bioceramics allowed the use of these materials as drug carriers, as drugs incorporated into porous structure would be subsequently released upon grafting/implantation into the surrounding tissue in a controlled manner, with well-established kinetics. Improved chemical stability, particulary toward acids is a desirable feature of these biomaterials, as calcium phosphates dissolve at pH<4.00. The objectives of this work included the synthesis, characterization and application of calcium phosphate biomaterials, i.e., mesoporous hydroxyapatites and monetite/silica nanocomposites. The mesoporous hydroxyapatite was studied as drug carriers. The stability of the nanocomposites, prepared via the sol-gel method by varying the content of TEOS, were investigated with respect to chemical (acid) and thermal stability, including a detailed study on the thermal decomposition kinetics of for the second mass loss of monetite and the nanocomposite CaPSil2. Among the twenty one porous hydroxyapatites prepared using two cationic surfactants, the hexadecyltrimethylammonium bromide and myristyltrimethylammonium bromide and sodium dodecyl sulfate as anionic surfactant, at various concentrations, heating rates, and calcination temperatures, only HA-MTAB-60-673/5 was mesoporous, whereas the remaining one were nanoporous, as indicated by N2 adsorption isotherms. HA-MTAB-60-673/5 was forwarded to drug uptake and release studies. This material was synthesized using 60 mmol.dm-3 myristyltrimethylammonium bromide as surfactant; the hybrid mesostructure intermediate was heated at 5 K.min-1 to 673 K and calcinated isothermally at 673 K for 6 h under O2 to yield HA-MTAB-60-673/5 with surface area of 89 m2.g-1, pore volume of 0,56 cm3.g-1, and average pore diameter of 23.96 nm. Increasing calcination heating rate did not increase crystallinity. The solid was able to uptake the antibiotic benzyl penicillin-G in a 2012 mg.g-1 ratio (drug/support) in 10 min, which was ~ 9-fold greater than that of precursor hydroxyapatite. The drug release profile followed the Higuchi model with the release of 52% of the drug in a time of 41 h. The covalent incorporation of silica onto the monetite surface yielded four monetite/silica nanocomposites that had unit cell volume and crystallinity reduced as silica content increased. Increased immobilization reduced Q3 species, as shown by 29Si NMR, and contributed substantially to mass loss on TG studies. Calcium phosphate/silica nanocomposites were more stable toward acid dissolution than the respective phosphate precursor, particularly at pH<4.00. The kinetics of the second mass loss stage of the thermal decomposition of monetite and CaPSil2 was studied by non-isothermal methods. FWO method provided activation energies (Ea) of 200.87 and 228.14 kJ.mol-1 and Coats-Redfern method provided activation energies (Ea) of 178.43 and 165.84 kJ.mol-1 and pre-exponential factors (A) of 9.53 x 1013 and 1.16 x 1013 s-1 for monetite and CaPSil2, respectively. A good description of experimental data was achieved by using the Avrami-Erofeev nucleation model (A2). / A principal aplicação dos fosfatos de cálcio é como biomateriais, para serem usados como enxerto ou implante ósseo. A obtenção de biocerâmicas mesoporosas permitiu o uso destes materiais como carreadores de fármacos, que são incorporados à estrutura porosa para serem subsequentemente liberados de forma controlada do enxerto ou implante ósseo para o tecido adjacente e com uma cinética bem estabelecida. Outra característica desejável aos biomateriais é possuir uma boa estabilidade química para não serem dissolvidos em meios ácidos, particularmente em pH<4,00. Os objetivos deste trabalho incluíram a síntese, caracterização e aplicação de biomateriais de fosfatos de cálcio, como hidroxiapatitas mesoporosas e nanocompósitos de monetita/sílica. A hidroxiapatita mesoporosa foi avaliada em ensaios de liberação de fármaco. A estabilidade dos nanocompósitos, preparados pelo método sol-gel, variando a concentração do TEOS nas sínteses, foi investigada com respeito à estabilidade química em sistemas ácidos, incluindo um estudo detalhado da cinética de decomposição térmica da segunda etapa de perda de massa da monetita e do nanocompósito CaPSil2. Das vinte e uma hidroxiapatitas porosas preparadas usando dois surfactantes catiônicos, o brometo de hexadeciltrimetilamônio e o brometo de miristiltrimetilamônio e o surfactante aniônico dodecilsulfato de sódio, variando-se as concentrações, as razões de aquecimento e as temperaturas de calcinação, somente a amostra HA-MTAB-60-673/5 foi mesoporosa, enquanto as demais foram nanoporosas, como indicaram as isotermas de adsorção de N2. A matriz HA-MTAB-60-673/5 foi aplicada em ensaios de liberação controlada de fármaco. Este material foi sintetizado usando o surfactante brometo de miristiltrimetilamônio na concentração de 60 mmol.dm-3; a mesoestrutura híbrida intermediária foi calcinada a uma razão de aquecimento de 5 K.min-1, na temperatura de 673 K por 6 h em condições isotérmicas e em O2, resultando na HAMTAB- 60-673/5 com área superficial de 89 m2.g-1, volume de poro de 0.56 cm3.g-1 e diâmetro médio de poro de 23.96 nm. As hidroxiapatitas nanoporosas apresentaram uma redução na cristalinidade. A matriz mesoporosa foi aplicada na liberação controlada do antibiótico benzil penicilina-G, tendo uma retenção (Nf) de 2012 mg.g-1 (fármaco/suporte) em 10 min, que foi aproximadamente nove vezes maior que a hidroxiapatita precursora. O perfil de liberação seguiu o modelo de Higuchi, com uma liberação de 52% do fármaco em um tempo de 41 h. A incorporação covalente da sílica na superfície da monetita resultou em quatro nanocompósitos de monetita/sílica com volume de célula unitária reduzido e menos cristalinos à medida que aumenta a quantidade sílica nas estruturas dos sólidos. O aumento da imobilização reduziu as espécies Q3, conforme RMN de 29Si, que contribuíram substancialmente para a perda de massa observada pela TG. Pelos ensaios de estabilidade química, os nanocompósitos de fosfato de cálcio e sílica tornaram-se mais estáveis quimicamente em relação ao fosfato precursor, particularmente em pH<4.00. A cinética de decomposição térmica da segunda etapa de perda de massa da monetita e CaPSil2 foi estudada por métodos não-isotérmicos. O FWO forneceu uma energia de ativação (Ea) de 200,87 e 228,14 kJ.mol-1 e o método de Coats-Redfern resultou em Ea de 178,43 e 165,84 kJ.mol-1 e fator pré-exponencial (A) de 9,53.1013 e 1,16.1013 s-1, para monetita e CaPSil2, respectivamente. Uma boa descrição dos dados experimentais foi obtida ao empregar o modelo de nucleação (A2) de Avrami-Erofeev.

Este trabalho, conduzido na forma de 2 subprojetos, avaliou: 1) o potencial preventivo de pastas à base de hidroxiapatita (nanopartículas de fosfato de cálcio) sobre a erosão e a abrasão do esmalte e dentina bovinos in vitro e in situ e 2) o efeito de um bochecho com solução de lactato de cálcio antes da escovação com dentifrício fluoretado sobre a erosão associada ou não à abrasão do esmalte e dentina bovinos in vitro e in situ. Na fase in vitro do 1o subprojeto, submeteram-se blocos de esmalte e dentina bovinos, por 5 dias, à erosão (coca-cola, pH 2,6, 4x/dia, 90s cada) + abrasão (escova elétrica + solução do dentifrício sem flúor, 10s cada, 2x/dia) e os tratamentos foram realizados após a abrasão, através da aplicação das seguintes pastas sobre os blocos (3 min, 2x/dia): 10% HAP, 10% HAP + 0,2% NaF, 20% HAP, 20% HAP + 0,2% NaF, 20% HAP + 2% NaF, placebo, 0,2% NaF, 2% NaF, MI paste, MI paste plus e controle. Na fase in situ, (4 fases, 5 dias/cada), 12 voluntários utilizaram dispositivo intrabucal palatino contendo 4 blocos de dentina e 4 de esmalte bovinos divididos nas condições: erosão e erosão+abrasão. Em cada fase foi feito tratamento com uma das seguintes pastas: 10% HAP, 10% HAP + 0,2% NaF, MI paste plus ou Placebo. O protocolo erosivo e abrasivo foi semelhante ao in vitro. No 2o subprojeto, a fase in vitro foi semelhante ao subprojeto 1, porém apresentou as condições erosão e erosão+abrasão. O estudo compreendeu os seguintes tratamentos: BCa + DF, BCa + DP, BP + DF e BP + DP. Após erosão, os blocos foram imersos em água deionizada (BP) ou solução de lactato de cálcio 150 mM (BCa; 1 min, sob agitação). Na condição erosão apenas, a solução de dentifrício fluoretado (DF) ou placebo (DP) foi pipetada sobre as amostras. A fase in situ foi semelhante ao experimento in vitro, porém com 15 voluntários e escovação por 15 s. A variável de resposta para os 2 subprojetos foi a análise de desgaste, avaliada por perfilometria (&#x3BC;m) e para a fase in situ do 1o subprojeto foi realizada também a análise por MEV-EDS. Os dados foram analisados pelos testes ANOVA/Tukey, Kruskal-Wallis/Dunn ou ANOVA a dois critérios/Bonferroni (p<0,05). In vitro, para o esmalte, as pastas à base de hidroxiapatita (10 e 20%), independentemente da presença do F, foram efetivas na prevenção da erosão associada à abrasão. Para a dentina, o efeito protetor foi encontrado apenas para as pastas contendo F, maior para aquelas com concentração mais elevada. In situ, apenas a pasta contendo 10% HAP foi efetiva para reduzir a erosão em esmalte quando comparada à pasta placebo. Nas demais condições testadas nenhuma das pastas utilizadas diferiu significativamente da placebo. Para o segundo subprojeto, o BCa + DF teve um efeito protetor apenas para a erosão de esmalte e dentina in vitro. Para a erosão associada à abrasão in vitro, assim como no estudo in situ, não houve diferença significativa entre os tratamentos. / This study, conducted in the form of two subprojects, evaluated: 1) the preventive potential of hydroxyapatite-based (calcium phosphate nanoparticles) pastes on erosion and abrasion of bovine enamel and dentin in vitro e in situ and 2) the effect of rinsing with a solution of calcium lactate before brushing with fluoride toothpaste on erosion associated or not with abrasion of bovine enamel and dentin in vitro e in situ. In the in vitro phase of the 1st subproject, bovine enamel and dentin blocks were submitted to erosion (coca-cola, pH 2.6, 4x/day, 90s each) + abrasion (electric toothbrush + fluoride-free toothpaste slurry, 10s each, 2x/day) for 5 days. Treatments were performed after abrasion, by applying the following pastes on the blocks (3 min, 2x/day): 10% HAP, 10% HAP + 0.2% NaF, 20% HAP, 20% HAP + 0.2% NaF, 20% HAP + 2% NaF, placebo, 0.2% NaF, 2% NaF, MI paste, MI paste plus and control. In the in situ phase (4 phases, 5 days each), 12 volunteers used intraoral palatal appliance containing four blocks of dentin and four blocks enamel divided into conditions erosion and erosion+abrasion. In each phase, treatment was done with one of the following pastes: 10% HAP, 10% HAP + 0.2% NaF, MI paste plus or Placebo. The erosive and abrasive protocol was similar to the in vitro phase. In the 2nd subproject, the in vitro phase was similar to subproject 1, but presented both conditions erosion and erosion + abrasion. The study included the following treatments: BCa + DF, BCa + DP, BP + DF e BP + DP. After erosion, the blocks were immersed in deionized water (BP) or calcium lactate solution 150 mM (BCa; 1 min, stirring). For the condition erosion only, the slurry of fluoride (DF) or placebo (DP) dentifrice was pipetted on the samples. The in situ phase was similar to the in vitro experiment, but 15 volunteers were included and brushing was conducted for 15 s. The response variable for the two subprojects was wear, evaluated by profilometry (&#x3BC;m). For the in situ phase of the 1st subproject, SEM-EDS was also performed. Data were analyzed by ANOVA/Tukey, Kruskal-Wallis/Dunn or two-way ANOVA/Bonferroni tests (p <0.05). In vitro , for enamel, 10 and 20% hydroxyapatitebased pastes, regardless the presence of F, were effective in preventing erosion associated with abrasion. For dentin, the protective effect was found only for Fcontaining paste and the effect was higher for those with higher F concentration. In situ, only pastes containing 10% HAP were effective in reducing enamel erosion as compared to the placebo paste. For the other tested conditions, none of the pastes used significantly differed from placebo. For the second subproject, the BCa + DF had a protective effect only for enamel and dentin erosion in vitro . For erosion associated with abrasion in vitro , as well as for the in situ study, no significant differences were detected among the treatments.

Injury to bone is one of the most prevalent and costly medical conditions. Clinical treatment of volumetric bone loss or hard-to-heal bony lesions often requires the use of proper bone grafting materials, with or without adjuvant anabolic therapeutics. Despite significant problems associated with autografting (donor site morbidity, limited supplies) and allografting (disease transmissions, high graft failure rates) procedures, synthetic bone grafts remain the least utilized clinically. Existing synthetic orthopaedic biomaterials rarely possess a combination of bone-like structural and biochemical properties required for robust osteointegration, scalable and user-friendly characteristics indispensable for successful clinical translations. This thesis tests the hypothesis that by recapitulating key structural elements and biochemical components of bone in 3- and 2-dimensional biomaterials, scalable synthetic bone grafts can be designed to enable expedited healing of hard-to-heal volumetric bone loss. Specifically, FlexBone, a 3-dimensional hydrogel scaffold encapsulating 50 wt% of structurally well integrated nanocrylstalline hydroxyapatite, the main inorganic component of bone, was developed. The large surface area of nanocrystalline hydroxyapatite combined with its intrinsic affinity to proteins and its excellent structural integration with the hydrogel matrix enabled FlexBone to both sequester endogenous protein signals upon press-fitting into an area of skeletal defect and to deliver exogenous protein therapeutics in a localized and sustained manner. We demonstrated that FlexBone enabled the functional healing of critical-size long bone defects in rats in 8 – 12 weeks with the addition of a very low dose of osteogenic growth factor BMP-2/7. This promising synthetic bone graft is now being explored for the delivery of multiple growth factors to expedite the healing of diabetic bony lesions. In addition, a 2-dimensional electrospun cellulose fibrous mesh was chemically modified with sulfate residues to mimic sulfated polysaccharide ECM components of skeletal tissues to enabled progenitor cell attachment and differentiation as well as controlled retention and localized/sustained delivery of protein therapeutics. This sulfated fibrous mesh is currently explored as synthetic periosteum to augment the osteointegration of devitalized structural allografts. Finally, a rat subcutaneous implantation model developed to examine the biocompatibility of newly developed biodegradable shape memory polymer bone substitutes is also presented.

Indiana University-Purdue University Indianapolis (IUPUI) / The effects of hydroxyapatite in a DAP-loaded MC carrier on dental pulp stem cells Introduction: Regenerative endodontic procedures (REP) require disinfection techniques to eliminate bacteria from the infected immature root canal system and promote new growth of the pulp-dentin complex. Double antibiotic paste (DAP), a mixture of ciprofloxacin and metronidazole, has shown efficacy in doing so while minimizing cytotoxicity on dental pulp stem cells (DPSC). Stem cells, scaffolding, and growth factors are necessary in the maturation, proliferation, and differentiation of mesenchymal stem cells into the root canal system. Nano-hydroxyapatite (n-HA) has a history of biocompatibility and, in addition, has shown promising effects as a tissue bioengineering material. Objective: The aim of this in vitro study was to investigate the proliferation and mineralization of DPSC in the presence of 1% DAP and methylcellulose (MC) with varying concentrations of nano-hydroxyapatite. Materials and Methods: DPSC were plated in 24-well plates containing culture media. The next day, semi-permeable 0.1 mm Transwell chambers were inserted into the wells to separate the reservoirs for medicaments. Treatment paste composed of methylcellulose containing 1% DAP with either 0.25%, 0.50%, or 1.0% nano-hydroxyapatite was added along with culture media. Methylcellulose alone and calcium hydroxide (Ultracal) were used as control groups. After 3 days, cells were evaluated for cytotoxic effects using an MTS proliferation assay (n = 10, in triplicate). DPSCs were also cultured with these medicaments for 7 days in osteogenic media and evaluated for alkaline phosphatase (ALP) activity and mineralization activity (n = 13, in triplicate). Comparisons between groups for differences in mineralization, BSA, and ALP activity were performed using analysis of variance (ANOVA), with different variances allowed for each group and a random effect included in the model to account for correlation within each of the three trials. A simulation-based model was used to adjust for multiple comparisons. Results: Addition of n-HA treatment groups increased mineralization significantly greater than calcium hydroxide, with MC alone and MC+DAP+0.5% HA providing the greatest effect. Regarding ALP, all HA concentrations performed significantly greater than MC and DAP concentrations. Proliferation demonstrated similar metabolic activity in all experimental groups with few comparisons significant. Conclusion: The challenge in REPs is to maintain survival, and preferably promote the proliferation and development of DPSCs into the pulp-dentin complex with a consistent treatment outcome. The combination of DAP with hydroxyapatite may allow for both disinfection and improved mineralization and cellular differentiation. This contribution has shown significant ability to increase stem cell differentiation into an osteogenic lineage as well as calcium deposition, indicating end goal results of regenerative procedures.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Regenerative endodontic procedures (REPs) are a type of endodontic treatment aimed at replacing damaged tooth structures, including dentin and root structures, as well as cells of the pulp-dentin complex. Double antibiotic paste (DAP) has been shown to be efficacious in achieving disinfection of the root canal system while minimizing cytotoxicity to dental pulp stem cells (DPSCs). Hydroxyapatite (HA) is an extracellular, mineralized component of bone that has shown much promise as a scaffold in the field of regenerative medicine. Objective: The objective of this study was to evaluate the effects of HA in a DAP loaded methylcellulose (MC) carrier on the differentiation and mineral deposition of DPSC over time. Materials and Methods: DPSCs were plated in 24-well plates with culture media. The following day, semi-permeable 0.1 m chambers were inserted into the wells to separate the reservoirs and permit delivery of medicaments. 100 L treatment paste composed of MC with 1% DAP and either 0.5% or 1.0% nano-HA was added, followed by additional culture media. After 3 days of treatment, medicaments were removed and DPSCs were cultured for an additional 9 days with replacement of media every 3-4 days. At Day 12, DPSCs were evaluated for alkaline phosphatase (ALP) activity using a biochemical assay and mineral deposition using an Alizarin Red S Ca2+ staining assay (4 wells/group). Comparisons between groups were performed using one-way analysis of variance (ANOVA) with a 5% significance level used for all tests. Results: A trend towards increased ALP and mineral deposition activity was noted among the groups with HA added to DAP with MC. Although these trends were not statistically significant, a trend towards increased ALP and mineral deposition was observed after 3-day medicament exposure. The results were similar to previous findings using 7-day medicament treatments. Conclusion: The addition of HA showed a trend towards improved differentiation and mineral deposition of DPSCs compared to DAP with MC. Although additional studies are required, these results showed suggest that even with a shortened treatment time, increased differentiation and mineral deposition of DPSCs may be possible. This study provides additional support that low concentration DAP in a MC carrier has potential application in regenerative endodontic procedures. The novel addition of HA may provide additional osteogenic potential.

Indiana University-Purdue University Indianapolis (IUPUI) / The objective of this study was to evaluate the in vivo performance of the hydroxyapatite (HA) coating and hydrofluoric acid (HF) etching zirconia (ZrO) implants and to compare the result with titanium (Ti) implants treated in a similar manner. A total of four different implant types were tested in this study. Threaded zirconia implants with HA coating (Test 1) and zirconia implants with HF-treated surfaces (Test 2) were used to compare to the same size of titanium implants treated in identical fashion (control 1 and control 2). All implants measured about 3.5 mm at the thread diameter and 7.0 mm in total length. Each rabbit received two zirconia and two titanium implants treated in the same manner (either HA-coated or HF-etched). The samples were implanted into the rabbit tibias and retrieved at 6 weeks. Upon retrieval, 24 specimens (6 samples for each group) were fixed and dehydrated. The samples were then embedded undecalcified in PMMA for histomorphometry to quantify the bone-to-implant contact (BIC). Another 24 samples were kept in 0.9% saline and were evaluated using removal torque (RT) analysis to assess the strength of the implant-to-bone interface. The histomorphometric examination demonstrated direct bone-to-implant contact for all four groups. HA particle separation from the implants surface was seen in a majority of the HA-coated samples. No signs of inflammation or foreign body reaction were found during examination. Due to the HA particle smear contamination in the ZrO-HA group, no data was collected in this group. The mean BIC at the first three threads of the Ti-HA, Ti-HF and ZrO-HF were 57.78±18.22%, 46.41±14.55% and 47.41±14.05%, respectively. No statistically significant difference was found pair-wise among these three groups. When comparing the BIC data with the machined-surface implants, a statistically significant difference was found between the Ti-HA versus Ti implant group and the Ti-HF versus Ti implant group. The mean bone area (BA) at the first three threads for Ti-HA, Ti-HF and ZrO-HF showed statistically significant difference (p<0.05) between the ZrO-HF and Ti-HA groups, favoring the ZrO-HF group. The value of the peak removal force could only be collected from the Ti-HA group during the removal torque test. The mean RT value for the Ti-HA group was 24.39±2.58 Ncm. When comparing the RT result with our pilot study using machined-surface implants, the Ti-HA group showed statistically significant (p<0.05) higher values than the machined-surface Ti implants. The result of this study proves the in vivo biocompatibility of all four implant types tested. In the three measurable implant groups, the histomorphologic analysis showed comparable osseointegration properties in this animal model.

Indiana University-Purdue University Indianapolis (IUPUI) / THE EFFECT OF FULL-CONTOUR Y-TZP CERAMIC SURFACE ROUGHNESS ON THE WEAR OF BOVINE ENAMEL AND SYNTHETIC HYDROXYAPATITE: AN IN-VITRO STUDY by Alaa Hussein Aref Sabrah Indiana University School of Dentistry Indianapolis, Indiana Full-contour yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations have been advocated recently in clinical situations where occlusal/palatal space is limited, or to withstand parafunctional activities. The objectives of this in-vitro study were to investigate the effects of different polishing techniques on the surface roughness of Y-TZP (Ardent Dental, Inc.) and to investigate the effects of different polishing techniques on the wear behavior of synthetic hydroxyapatite (HA) and bovine enamel. An in-vitro study was conducted by fabrication of 48 Y-TZP sliders (diameter = 2 mm × 1.5 mm in height) using CAD/CAM technique; then the samples were embedded in acrylic resin using brass holders. Samples were then randomly allocated into four groups according to the finishing/polishing procedure: G1-as-machined (n = 8), G2- glazed (n = 16), G3-diamond bur-finishing (Brasseler, USA) (n = 8) and G4- G3+OptraFine polishing kit (Ivoclar-Vivadent) (n = 16). Thirty-two sintered HA disks (diameter = 11 mm × 2.9 mm in height) and 16 bovine enamel samples with a minimum surface area of 64 mm2 were mounted in brass holders. Baseline surface roughness (Ra and Rq, in μm) were recorded using a non-contact profilometer (Proscan 2000) for all the samples. A two-body pin-on-disk wear test was performed for 25,000 cycles at 1.2 Hz in which the four zirconia groups were tested against HA, and only G2-glazed and G4- G3+OptraFine polishing kit (Ivoclar-Vivadent) were tested against bovine enamel. Vertical substance loss (μm) and volume loss (mm3) of HA were measured (Proscan). Zirconia height loss was measured using a digital micrometer. One-way ANOVA was used for statistical analysis. The results indicated that surface roughness measurements showed significant differences among the surface treatments with G1 (Ra = 0.84, Rq = 1.13 μm) and G3 (Ra = 0.89, Rq = 1.2 μm) being the roughest, and G2 (Ra = 0.42, Rq = 0.63 μm) the smoothest. The glazed group showed the highest vertical loss (35.39 μm) suggesting wear of the glaze layer, while the polished group showed the least vertical loss (6.61 μm). HA antagonist volume loss and vertical height loss for groups (G1, G2 and G3) were similar, while polished group (1.3 mm3, 14.7 μm) showed significant lower (p = 0.0001) values. Antagonist height loss and antagonist volume loss were significantly higher for bovine antagonist than for HA antagonist (197.6 μm/116.2 μm, and 28.5 mm3/17.7 mm3 for bovine against glazed/polished zirconia sliders, respectively) (p < 0.0001). From the results it can be concluded that glazed zirconia provided an initially smooth surface, but a significant increased antagonist wear compared with the polished surface was seen. Bovine enamel showed higher wear compared with HA, which suggested that more studies should be performed to validate the use of bovine enamel as a substitute for human enamel in wear studies.