Physical and mechanical properties of four 3D-printed resins at two different thick layers: An in vitro comparative study.

OBJECTIVES: This in vitro comparative study aimed to evaluate the physical and mechanical properties of four 3D-printed resins with two different thickness layers. METHODS: Four printed resins (VarseoSmile Crown Plus, VSC; NexDent C&B MFH, MFH; Nanolab 3D, NNL; and Resilab 3D Temp, RSL) were printed with 50 µm and 100 µm layer thickness, resulting in 80 bars measuring 25 × 2×2 mm. The specimens underwent a Raman spectroscopy for degree of conversion, confocal laser scanning microscopy for surface roughness (Sa), three-point bending test for flexural strength and elastic modulus, and a Vickers hardness test (VHN). Data was tested for normality using the Shapiro-Wilk, two-way ANOVA, and Tukey test (α = 0.05) for statistical analysis. RESULTS: The layer thickness affected all performed tests, but the elastic modulus (p < 0.001). Specimens with 100 µm showed, in general, worse results outcomes than those with 50 µm (p < 0.001). However, within the limitations of this comparative in vitro study, it could be concluded that the tested resins and layer thicknesses directly influenced physical and mechanical properties. SIGNIFICANCE: The physical and mechanical properties of three-dimensional printed restorations can be affected by the layer thickness, which can interfere with the choice of the 3D printing resin for a desired clinical outcome.

Deep occlusal carious lesions clinical management by Brazilian dentists: a nationwide e-survey / Manejo clínico de lesões cariosas oclusais profundas por cirurgiões-dentistas brasileiros: uma pesquisa eletrônica nacional

Objective: To investigate the clinical management of deep occlusal carious lesions in permanent teeth by Brazilian dentists. Material and Methods: This cross-sectional study included a sample of 732 Brazilian dentists who responded to an electronic questionnaire composed of 20 questions addressing socio-demographic information, training and professional activity characteristics, and clinical management of deep carious lesions. Descriptive analysis was performed, considering relative and absolute frequencies and 95% confidence intervals. The association between the dentists' variables of interest (age group, type of higher education institution, years in practice, highest academic degree completed and main sector of professional activity) and the mean number of incorrect answers regarding deep carious lesions management was analyzed by Analysis of Variance (ANOVA), followed by the Bonferroni post-test (p<0.005). Results: Stepwise removal was the strategy pointed out by most dentists (42.8%). However, 16% of the dentists selected nonselective carious tissue removal. Furthermore, 45.6% of the dentists disagreed with maintaining carious tissue over the pulp in deep lesions with a risk of pulpal exposure. When using instruments to remove carious dentine, 17% of the dentists chose a diamond burn while 13% preferred tungsten carbide burs. Dentists who graduated from public institutions had a lower mean of non-conservative decisions than those from private institutions. Dentists with master's or doctoral degrees were more conservative, as well as dentists from public service compared to those from the private sector. Conclusion: The dissemination of conservative approaches in the management of deep carious lesions needs to be strengthened and increasingly based on updated scientific literature.(AU)

Objetivo: Investigar o manejo clínico de lesões cariosas oclusais profundas em dentes permanentes por cirurgiões-dentistas brasileiros. Material e Métodos: Este estudo transversal incluiu uma amostra de 732 dentistas brasileiros que responderam a um questionário eletrônico composto por 20 questões abordando informações sociodemográficas, formação, características da atividade profissional e manejo clínico de lesões cariosas profundas. Foi realizada análise descritiva, considerando frequências relativas e absolutas, e intervalos de confiança de 95%. A associação entre as variáveis de interesse (faixa etária, tipo de instituição de ensino superior, anos de prática, maior titulação acadêmica concluída e principal setor de atividade profissional) dos cirurgiões-dentistas e a média de acertos no manejo de lesões cariosas profundas foi analisada pela Análise de Variância (ANOVA), seguida do pós-teste de Bonferroni (p<0,005). Resultados: A remoção seletiva foi a estratégia apontada pela maioria dos cirurgiões-dentistas (42,8%). No entanto, 16% dos dentistas selecionaram a remoção não seletiva do tecido cariado. Além disso, 45,6% dos dentistas discordaram da manutenção de tecido cariado sobre a polpa em lesões profundas com risco de exposição pulpar. Ao usar instrumentos para remover a dentina cariada, 17% dos dentistas escolheram uma broca diamantada, enquanto 13% preferiram brocas de carboneto de tungstênio. Cirurgiões-dentistas formados em instituições públicas apresentaram menor média de decisões não conservadoras do que os de instituições privadas. Os cirurgiões-dentistas com mestrado ou doutorado foram mais conservadores, assim como os cirurgiões-dentistas do serviço público em relação aos do setor privado. Conclusão: A disseminação de abordagens conservadoras no manejo de lesões cariosas profundas precisa ser fortalecida e cada vez mais baseada em literatura científica atualizada (AU)

Randomized clinical trial of four adhesion strategies: A 42 month study.

CONTEXT: The adhesives clinical effectiveness has been extensively reported for noncarious cervical lesions (NCCLs). However, there is a lack of information about the adhesive systems strategies and their effect on NCCL restoration longevity. AIMS: This study aims to evaluate a 42-month performance of four dentin adhesive systems used for the restorative treatment of NCCLs. SETTINGS AND DESIGN: NCCLs were randomly divided into four groups: (1) Scotchbond multi-purpose (MP); 2: Single bond plus (SB); 3: Scotchbond SE (SE); and 4: Easy bond (EB). SUBJECTS AND METHODS: NCCLs (125) were randomly distributed: (1) MP; (2) SB; (3) SE; and (4) EB and were restored with a nanofilled resin-composite, evaluated along 18-36-42 months. STATISTICAL ANALYSIS USED: Kruskal-Wallis test: Comparison among the adhesive systems in each period. Friedman analysis: Comparison along the periods. Kaplan-Meier: Survival analysis. RESULTS: Baseline and 42-month retention (RET) rates (%) were 100/100 for MP; 100/94.74 for SB; 100/87.5 for SE; and 100/100 for EB. The cumulative failure percentage was 9.52% for MP, 9.52% SB, 15.8% SE, and 10% EB. Restorations survival was not dependent on the used adhesive type. Marginal adaptation (MA) was similar to each group, but EB presented noticeable marginal deterioration. Wear was noticed in the 3-step etch-and-rinse (MP) restorations evaluated after 42 months. For the EB, baseline and 18-month wear evaluation were statistically similar. After 36 and 42 months, wear was also similar for EB. CONCLUSIONS: Adhesive systems showed similar performance within most important adhesive bonding efficiency achievement parameters: RET, MA, interfacial staining, recurrent caries, and postoperative sensitivity evaluated during 42 months.

On the understanding of zinc-oxide eugenol cement use prior to etch-rinse bonding strategies.

CONTEXT: Zinc-oxide eugenol (ZOE) is frequently used due to its satisfactory biological response, sedative effect on the pulp, and easy removal. However, literature is very controversial about the influence of the temporary cement-containing eugenol on the bond strength properties. AIMS: This study aims to clarify the literature controversy by evaluating the bond strength of ZOE or ZOE-free applied before bonding procedures and the 7-day resting period after the first session. SETTINGS AND DESIGNS: Twelve recently extracted third molars were randomly divided into three groups: Group 1: Control (without treatment), Group 2: Temp-Bond NE; Group 3: Temp-Bond. SUBJECTS AND METHODS: After temporary restorations, the teeth were immersed in distilled water and stored for 7 days at 37°C. The temporary cement was mechanically removed, and prophylaxis was performed. The adhesive procedures were performed, and a 6-mm-high composite resin block was built. The teeth were immediately stored at 100% relative humidity at 37°C for 24 hours. Specimens with 0.7 (±0.2) mm2 of cross-sectional area were obtained and subjected to a microtensile bond strength (µTBS) test at 1 mm/min until failure. STATISTICAL ANALYSIS USED: Analysis of variance (ANOVA) and Tukey's post hoc test were used for statistical analysis. RESULTS: ZOE or ZOE-free cement did not interfere in the µTBS between resin composite and dentine when used with a two-step-etch-rinse adhesive material, considering 7 days of resting period after the first session, by the ANOVA and Tukey's post hoc test (P < 0.05). CONCLUSIONS: The authors recommend the removal of the temporary cementation at least seven days after the first session and suggest that the clinicians follow-up further studies to use the cement in case its removal is recommended within a longer period.

Strength of a Zirconia-Reinforced Lithium Silicate Ceramic: Acid-Etching Time and Resin Cement Application Effects.

This study aimed to evaluate the effect of hydrofluoric (HF)-acid-etching time and the impact of a resin-cement layer on the biaxial flexural strength and structural reliability of a zirconia-reinforced lithium silicate (ZLS) glass ceramic. Disc-shaped specimens (n = 15) were divided according to: etching time (conditioning with 10% HF acid for 20, 40, and 60 seconds), and application of a resin-cement layer. Biaxial flexural, contact angle, and roughness analyses were performed. When the resin-cement layer was not present, flexural strength data increased with increasing etching times: 20 seconds = 250.8 MPa; 40 seconds = 278.4 MPa; 60 seconds = 342.9 MPa. Application of resin cement increased the strength values (20 seconds of acid etching on specimens with a resin-cement layer = 341.8 MPa). Different etching times did not affect the roughness of ZLS, and the contact-angle analysis presented lower values for 60 seconds of acid etching. The flexural strength of ZLS was only sensitive to surface changes when less exposure time was conducted. Longer etching times (40 and 60 seconds) should be considered for conditioning ZLS ceramic along with adhesive cementation.

Micro-CT and FE-SEM enamel analyses of calcium-based agent application after bleaching.

OBJECTIVES: The objective of the present study is to evaluate the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on bleached enamel. MATERIALS AND METHODS: A bleaching agent (35% hydrogen peroxide) was applied, 4 × 8 min on premolar teeth (n = 8). A CPP-ACP paste was applied for 7 days. Prior and post-treatment, microtomography images were obtained and 3D regions of interest (ROIs) were selected, from outer enamel, extending to 110.2-µm depth. CT parameters of structure: thickness (St.Th), separation (St.Sp), and fragmentation index (Fr.I.) were calculated for each (ROI). Data was submitted to paired t tests at a 95% confidence level. The samples were evaluated at 3000 to 100,000 magnification. Quantitative analysis of enamel mineral content was also determined by SEM EDX. RESULTS: There was a significant increase in structure thickness and calcium content. The phosphorus content increased after bleaching. There was also a decreased separation and fragmentation index on the outer enamel to a depth of 56.2 µm (p < 0.05). There were no changes at 110.2-µm depth for the bleaching CPP-ACP association. A covering layer and decreased spaces between the hydroxyapatite crystals appeared around the enamel prisms, 7 days after the CPP-ACP application. CONCLUSIONS: The application of a CPP-ACP provides a compact structure on the enamel's outer surface, for 7 days, due to calcium deposition. CT parameters seem to be a useful tool for mineralizing and remineralizing future studies. CLINICAL RELEVANCE: CPP-ACP neutralizes any adverse effects on enamel surface when applied during a week after bleaching and minimizes any side effects of the bleaching treatment due to a more compact structure.

Zirconia-Reinforced Lithium Silicate Ceramic - A 2-Year Follow-up of a Clinical Experience with Anterior Crowns.

The aim of this manuscript is to describe 2-year follow-up of a clinical experience with a zirconia-reinforced lithium silicate ceramic for an anterior rehabilitation with single metal-free crowns. The maxillary-central incisor teeth crowns were made by zirconium-reinforced lithium silicate and covered with porcelain were obtained with a digital impression with the intra-oral scanner of the CEREC system as a basis for virtual design, as well as a laminate for the left lateral maxillary incisor, based on a "double scanning" technique. Lithium silicate material seems to be a safe and satisfactory alternative for anterior crowns' rehabilitation.

Zirconia Rehabilitation Focused on the Emergence Profile: A Case Report.

The first choice for anterior rehabilitation has been metal-free materials due to their successful aesthetic results. However, the definitive clinical work accuracy may be affected by the lack of clinicians' expertise and familiarization with the latest techniques, as well as recurrent laboratory procedures. This manuscript presents a clinical experience with zirconia ceramic for anterior crowns and zirconia CAD/CAM abutments, including both clinical and laboratory steps after the implant installation. The 'emergence profile' and the 'double scanning' techniques obtained by the waxing technique appear to be a very promising procedure for aesthetic improvement of the single-implant zirconia restoration in anterior teeth.

Experimental and FE displacement and polymerization stress of bonded restorations as a function of the C-Factor, volume and substrate stiffness.

OBJECTIVES: To determine the free surface displacement of resin-composite restorations as a function of the C-Factor, volume and substrate stiffness, and to compare the results with interfacial stress values evaluated by finite element analysis (FEA). METHODS: Surface displacement was determined by an extensometer using restorations with 4 or 6mm diameter and 1 or 2mm depth, prepared in either bovine teeth or glass. The maximum displacement of the free surface was monitored for 5 min from the start of photoactivation, at an acquisition rate of 1s(-1). Axisymmetric cavity models were performed by FEA. Structural stiffness and maximum stresses were investigated. RESULTS: For glass, displacement showed a stronger correlation with volume (r=0.771) than with C-Factor (r=0.395, p<0.001 for both). For teeth, a stronger correlation was found with C-Factor (r=0.709; p<0.001) than with volume (r=0.546, p<0.001). For similar dimensions, stress and displacement were defined by stiffness. Simultaneous increases in volume and C-Factor led to increases in stress and surface displacement. Maximum stresses were located at the cavosurface angle, internal angle (glass) and at the dentine-enamel junction (teeth). The displacement of the restoration's free surface was related to interfacial stress development. CONCLUSIONS: Structural stiffness seems to affect the shrinkage stress at the tooth/resin-composite interface in bonded restorations. Deep restorations are always problematic because they showed high shear stress, regardless of their width. FEA is the only tool capable of detecting shear stress due to polymerization as there is still no reliable experimental alternative.

Effects of curing protocols on fluid kinetics and hardness of resin cements.

The effects of polymerization protocols on water sorption/solubility, the diffusion coefficient (D), the flux (J), and the hardness (KH) of two resin cements were evaluated. The materials were manipulated and divided into three groups (n=6) according to the curing protocol: PA=photoactivation (40 s); DP=delayed photoactivation (10 min self-curing plus 40 s photoactivated); CA=chemical activation. After desiccation, the specimens were weighed, stored in water (37ºC), evaluated over 28-days, and hardness recorded. Chemical activation resulted in lower net water uptake, D, and J for RelyX ARC (RX). For Variolink II (VL), CA yielded equivalent D and lower J; however, photoactivation resulted in lower net water uptake. Hardness of VL was less affected by the water storage, irrespective of the polymerization protocol. Considering the water diffusion parameters, VL demonstrated immediate photoactivation dependence; for RX, a chemical activation. Different polymerization protocols affect the fluid kinetics and the hardness of the resin cements tested.

Esthetic and functional rehabilitation of crowded mandibular anterior teeth using ceramic veneers: a case report.

The use of ceramic veneers to restore crowded teeth in the maxilla has been widely discussed in the literature. However, the use of this technique in the mandible has received little attention. Therefore, this case report describes the treatment of crowded mandibular anterior teeth using ceramic veneers. The primary treatment challenge in this region is the reduced tooth structure available for rehabilitation. Proper communication between the clinician and dental technician is required to achieve clinical success. This article presents a straightforward treatment plan and restorative technique that includes both the clinical and laboratory sequences necessary for predictable and stable postoperative outcomes.

Fracture resistance of teeth restored with different resin-based restorative systems

The aim of the present study was to evaluate the fracture resistance of teeth restored with resin composite. Forty-eight maxillary premolar teeth were chosen and randomly divided to six groups: G1 (control): sound teeth; G2: MOD preparation, unrestored; G3: MOD + Adper Single Bond 2/P60; G4: MOD + Adper Easy One/P60; G5: MOD + P90 restorative system; G6: MOD + Adper Easy One/P90 Bond/P90. Specimens were subjected to compressive axial loading (0.5 mm/min). Flexural strength and the modulus of elasticity were also tested (n = 7). The only statistical equivalence with sound teeth was noted for G3 (p < 0.05). Flexural strength and the modulus of elasticity varied among the composites tested (n = 10). The reestablishment of the resistance to fracture in premolars subjected to Class II MOD preparations is restorative-system-dependent. The silorane restorative system is not able to recover the resistance to fracture.

Fracture resistance of teeth restored with different resin-based restorative systems.

The aim of the present study was to evaluate the fracture resistance of teeth restored with resin composite. Forty-eight maxillary premolar teeth were chosen and randomly divided to six groups: G1 (control): sound teeth; G2: MOD preparation, unrestored; G3: MOD + Adper Single Bond 2/P60; G4: MOD + Adper Easy One/P60; G5: MOD + P90 restorative system; G6: MOD + Adper Easy One/P90 Bond/P90. Specimens were subjected to compressive axial loading (0.5 mm/min). Flexural strength and the modulus of elasticity were also tested (n = 7). The only statistical equivalence with sound teeth was noted for G3 (p < 0.05). Flexural strength and the modulus of elasticity varied among the composites tested (n = 10). The reestablishment of the resistance to fracture in premolars subjected to Class II MOD preparations is restorative-system-dependent. The silorane restorative system is not able to recover the resistance to fracture.

Influence of restorative techniques on marginal adaptation and dye penetration around Class V restorations.

The aim of this study was to observe the influence of restorative techniques on marginal adaptation and dye penetration around Class V restorations simulating abfraction lesions. Sixty mandibular premolars were divided into six groups (n = 10) using different restorative materials. Cavity preparation presented the gingival wall localized in dentin and the incisal wall in enamel. Replicas of abfraction lesions were obtained and viewed under a stereomicroscope for adaptation assessment. All teeth were subjected to thermocycling and mechanical load cycling and immersed in 0.5% methylene blue dye (pH 7.2) for four hours. The results were tabulated and submitted to Kruskal-Wallis tests, which were significant for the dentin margin with lower microleakage values for primer/Vitremer, followed by Clearfil SE Bond/Durafill VS and Clearfil SE Bond/Z100 in qualitative and quantitative methods (P < 0.05). The enamel margin had no significant difference for microleakage values for all groups. There was no statistically significant difference among the substrates for marginal adaptation. The Spearman coefficient illustrated a direct relation between enamel and dentin for microleakage evaluation (P < 0.0001). The data demonstrated no difference for marginal fit by chi-square test. It can be concluded that all groups had microleakage in different degrees, with the lowest values for resin-modified glass ionomer.

Effectiveness of self-adhesive luting cements in bonding to chlorhexidine-treated dentin.

OBJECTIVES: The aim was to investigate the microtensile bond strength (µ-TBS) and failure pattern of self-adhesive luting cements (SLC) to dentin pre-treated with different concentrations of chlorhexidine (CHX) solutions. METHODS: The occlusal enamel was removed from 30 extracted sound human molars in order to expose a flat dentin. Resin-composite (Filtek Z250, 3M ESPE) discs (12 mm in diameter, 6.0mm thickness) were cemented to the smear layer-covered dentin using the SLC [RelyX U100, 3M ESPE (U100); Multilink Sprint, Ivoclar Vivadent (MS)] with 0.2% or 2.0% CHX solutions. Results were compared with the control, untreated dentin. Six groups were then created based on the SLC and dentin pre-treatment (n=5). After 24h of water storage, restored teeth were serially sectioned into beams with a cross-sectional area of 0.8mm(2) at the bonded interface. Subsequently, specimens were tested in tension with a crosshead speed of 0.5mm/min in a universal testing machine, and the failure patterns were classified. Two-way ANOVA and Tukey's tests were performed (α=0.05). Additionally, 18 teeth were subjected to energy-dispersive X-ray spectroscopy (EDS) analysis and micromorphology characterization of the smear layer-covered dentin and 0.2% or 2.0% CHX-treated dentin surfaces. RESULTS: The µ-TBS obtained for both control groups were significantly higher, regardless of the CHX concentration and/or the cement used. Bond strengths were significantly higher for U100 than for MS, except when 2.0% CHX was applied. Fractographic analysis indicated that most failures in the control groups occurred cohesively in the SLC. Pre-treated dentin with 0.2% and 2.0% CHX solutions presented higher incidences of adhesive failures. EDS/SEM analysis exhibited varied concentrations of chlorine ions and crystal-shaped precipitates, depending upon the CHX concentration. SIGNIFICANCE: Pre-treatment of dentin with 0.2% or 2.0% CHX adversely affects the bonding efficacy when associated with the SLCs tested.

Methacrylate- and silorane-based composite restorations: hardness, depth of cure and interfacial gap formation as a function of the energy dose.

OBJECTIVES: To investigate the influence of the energy dose on the hardness, polymerization depth, and internal adaptation of silorane and methacrylate-based posterior composites in Class II restorations with different bonding approaches. MATERIALS AND METHODS: Class II preparations were made on the mesial and distal surfaces of extracted third molars and randomly distributed into 6 groups (n=20), according to the restorative systems [methacrylate-based composite: Filtek P60+Adper Single Bond 2 (etch-and-rinse adhesive) - P60/SB; Filtek P60+Adper Easy One (self-etching adhesive) - P60/EO; silorane-based composite: Filtek P90+P90 System Adhesive - P90 (self-etching adhesive)] and the energy dose (20 and 40 J/cm(2)). Resin composites were applied in two increments, individually photoactivated using an LED light-curing unit. After 24 h, all restorations were mesio-distally sectioned. Hardness was evaluated along the transversal section of the fillings (1-4 mm below the restoration surface) using a load of 50 g for 5 s. In order to evaluate the internal gap formation, specimens were air dried and 1% acid red propylene glycol solution was applied to the internal margins for 20 s. Specimens were then water rinsed, air dried, and digitally image recorded. The internal gap (%) was calculated as the ratio between the stained margins and the total length of the internal margin. Kruskal-Wallis test was conducted to evaluate internal gap formation, and three-way ANOVA and Tukey's test were performed to evaluate hardness/polymerization depth (α=0.05). RESULTS: Regarding the internal gap formation, a significant difference was observed among all groups (P60/EOP90; p<0.05). The highest energy dose (40 J/cm(2)) produced significant increase in the KHN only for Filtek P90 (p<0.05). SIGNIFICANCE: Although a higher energy dose produces a slight increase in hardness for the silorane based composite, it also increases the internal gap formation. Dose of 20 J/cm(2) seems to be more suitable as it provides reduced internal gaps and satisfactory hardness. In addition, gap formation seems to be a consequence of an underperformed bonding approach rather than the differences in the resin-composite formulation.

Experimental and FE shear-bonding strength at core/veneer interfaces in bilayered ceramics.

OBJECTIVES: To compare the bond strength of a ceramic veneer material to two different ceramic core materials using shear strength testing and finite element analysis (FEA). METHODS: 15 blocks of ceramic cores were made of each of IPS e.max ZirCAD (Ivoclar-Vivadent, Schaan, Liechtenstein) (ZirCAD) and lithium disilicate IPS e.max CAD (LS). These were veneered using IPS e.max Ceram (Ceram) according to the manufacturers' instructions. Samples were then mounted, placed inside a shear testing jig and loaded at their core/veneer interfaces with a universal testing machine. Fractured specimens were then examined fractographically at 45×. An independent t-test and a Mann-Whitney U test were used to detect differences in bond strengths and the patterns of failure between the two groups, respectively (p>0.05). Two-dimensional plane stress FE-models were constructed and subjected to shear loading simulating the experimental conditions. RESULTS: Mean shear stresses (MPa) were 28.8 (9.5) for ZirCAD/Ceram and 29.1 (8.3) for LS/Ceram. Differences were not statistically significant. Fracture patterns were significantly different between the 2 groups as all ZirCAD/Ceram samples broke adhesively at their interface while LS/Ceram samples broke cohesively in the veneer or the core or had mixed adhesive/cohesive failure. Stress distributions in the FEA models were also different, corresponding to the variable fracture patterns in the 2 groups. SIGNIFICANCE: Although shear stresses were similar, fractographic analysis and finite element modeling suggested better bonding between the veneering ceramic and the glass-ceramic than to the zirconia cores. Improved bonding techniques are necessary to prevent clinical delamination of veneered zirconia restorations.

3D-FE analysis of soft liner-acrylic interfaces under shear loading.

AIM: To analyze the distribution of stresses at the bond interface of Molloplast-B soft-liner attached to PMMA acrylic surface of different geometries (smooth and rough) and at different load-application distances by 3D-FEA modeling of typical shear-bond test. Methodology Three-dimensional finite element analysis (3D-FE) was performed utilizing Patran and Marc softwares (MSC.Software, USA). Models of Molloplast-B disk liner (diameter: 8mm, thickness: 3mm) bonded to smooth and rough acrylic geometries were designed. A total of 8 models (4 models for each surface geometry) were used to analyze Von Mises, maximum principal and shear stresses for the nodes corresponding to the vertical diameter of the acrylic-liner interface when applying a uniform shear-loading at different distances from the interface; 0.25, 0.5, 1, and 2mm. Materials properties were assumed to be isotropic, homogeneous, linear and elastic. RESULTS: Shear loadings, at various distances from the bond-interfaces, produced different magnitudes of shear and tensile stresses. They were more uniform for both smooth and rough geometries when loading was applied at smaller distances from the interface (0.25 and 0.50). The maximum shear stress did not surpass maximum tensile stress in the areas subjected to the highest stress. These values were higher for the models with increased distances and bending moment associated with rough surfaces. CONCLUSIONS: It can be concluded that in conducting shear bond tests, shear and tensile stresses are present regardless of the distance from the bond interface at which the shearing stress is applied. However, at increased distances from the bond interface, tensile stresses are greater than shear stresses. When shear stress is applied at shorter distances from the bond interface (0.25 or 0.50mm), and regardless of bond-interface geometry; there is more uniform stress distribution and lower effect of bending moment. However, in vitro studies of bond strengths between soft liners and acrylic substrates obtained by shear test should be approached with caution, considering the distance of load application and the surface treatment of the substrate as the most important factors that could interfere with the shear test values.