Stress distribution on teeth restored with veneers using various incisal preparation designs: A 3D finite element analysis study.

STATEMENT OF PROBLEM: The type of veneer preparation is often chosen according to the patient's tooth structure and occlusion. Taking biomechanics into account in this decision-making process provides the clinician with more technical information on how to improve the clinical longevity of restorations. However, biomechanical analyses of veneer preparation designs are sparse. PURPOSE: The purpose of this 3-dimensional (3D) finite element analysis with microcomputed tomography (µCT) data obtained from realistic models was to assess the influence of different preparations for ceramic and composite resin veneers on restoration and resin layer stress distribution. MATERIAL AND METHODS: Four replicas of a central incisor were printed and prepared for laminate veneers with 4 different incisal edge designs: shoulder (SH), palatal chamfer (PC), palatal chamfer and oblique fracture involving the distal angle (OF-PC), and palatal chamfer involving horizontal incisal fracture (IF-PC). After fabrication and cementation of the veneers, the restored replicas were assessed with µCT, and 3D finite element models were built. A 100-N load was applied on the palatal surface at 60 and 125 degrees relative to the longitudinal axis. Maximum principal stress and stress distribution on the veneers, cement layer, and tooth structure were calculated and analyzed. RESULTS: The SH preparation exhibited better stress distribution than the PC preparation, and the cement layer and the veneer were subjected to lower stress. The IF-PC preparation had better stress distribution than the OF-PC. The shoulder and IF-PC showed higher stress on laminate veneers, but lower stress on the cement layer. Ceramic veneers exhibited lower stress than composite resin veneers. CONCLUSIONS: The different incisal preparations for laminate veneers influenced stress distribution on restorations and on the resin cement layer. The shoulder type preparation showed better stress distribution and the composite resin veneers showed unfavorable results compared with the ceramic veneers.

Influence of root fragility and irrigation on external root temperature variation during preparation for fiberglass posts.

Background: This paper analyses the effects of root canal fragility and irrigation on external temperature change (ΔT) of different sections of roots during post-space preparation. Material and Methods: Forty endodontic treated human premolars were evaluated. Roots were divided into four groups based on their root wall thickness (fragile or non-fragile), and whether they received irrigation (yes or no) during post-space preparation. Initial root canal temperature was kept at 37°C. ∆T was evaluated with thermistors attached to the cervical and apical thirds of the roots during two preparation steps: 1) removal of gutta-percha with Largo drills, and 2) using the specific drill for post-space preparation for cementation of fiber-reinforced posts. In the irrigated groups, we used a 2% chlorhexidine solution during the exchange of drills. ∆T data was analyzed using four-way ANOVA with repeated measures and Tukey's test (α = 0.05). Results: Significant differences in ∆T based on root fragility (p = 0.017), root canal third (p = 0.013), and preparation step (p = 0.006). We found that non-fragile roots tended to have higher ∆T than fragile roots, particularly in the apical third, during the use of the second drill. Irrigation did not have a significant effect on temperature variation, regardless of root wall thickness or the third evaluated (p> 0.05). Conclusions: Findings suggest that root wall thickness and the third evaluated influence temperature changes during post-space preparation for cementation of posts. Non-fragile roots showed greater temperature variation than fragile roots, while irrigation did not significantly impact temperature changes. Key words:Temperature, post and core technique, tooth preparation.

Patient-related outcomes of conventional impression making versus intraoral scanning for prosthetic rehabilitation: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Intraoral scanning has been reported to be preferred by patients over conventional impression making. Nevertheless, information regarding patient-related outcomes for conventional impression making and digital scanning is sparse. PURPOSE: The purpose of this systematic review and meta-analysis was to analyze patient-related outcomes of intraoral scanning and conventional impression methods. The primary outcomes evaluated were patient preference and satisfaction, and the secondary outcomes discomfort, nausea, unpleasant taste, breathing difficulty, pain, and anxiety. MATERIAL AND METHODS: Electronic and manual searches were performed for clinical trials that evaluated patient-related outcomes for intraoral scanning and conventional impression making for prosthetic rehabilitation. The Cochrane Collaboration risk of bias tool and Newcastle-Ottawa scale were used to assess the quality of the studies. Random-effects models using mean difference were used for meta-analyses. Heterogeneity was assessed using the Cochran Q test and I2 statistics (α=.05). RESULTS: The search strategy identified 1626 articles, and 11 studies were included in the meta-analyses. Patients preferred intraoral scanning to conventional impression making. The mean difference for patient preference was 15.02 (95% confidence interval of 8.33 - 21.73; P<.001). Discomfort, absence of nausea, absence of unpleasant taste, and absence of breathing difficulty were also significantly different (P<.05). CONCLUSIONS: Intraoral scanning is a suitable alternative to conventional impression procedures, promoting less discomfort for patients sensitive to taste, nausea, and breathing difficulty than when conventional impression making techniques are used.

Effect of S. mutans biofilm on the hybrid ceramic-resin cement bond strength assessed by different methods

Aim: The purpose of this study was to investigate the biofilm effect on the hybrid ceramic-resin cement bond strength (BS) by comparing two methods. Methods: Teeth were distributed into groups (n=5), according to the resin cement (Maxcem Elite-(MC) or NX3 Nexus-(NX)) and degradation method (24h or 7 days in distilled water; 7 or 30 days incubated with biofilm and 30 days in sterile media). Treated surfaces of Vita Enamic blocks (5x6x7mm) were luted to treated or no treated dentin surfaces and light-cured. After 24h, beams were obtained (1x1x10mm) and stored accordingly. The flexural bond strength (FBS) was assessed by four-point bending test. Additional beams were obtained from new teeth (n=5), stored for 24h or 7 days in distilled water, and submitted to a microtensile bond strength (µTBS) assay. Failure modes were determined by scanning electron microscopy (100X). The flexure strength of the cements (n=10) was assessed by a four-point bending test. Data were analyzed by 1 and 2-ways ANOVA, and Tukey's test (α=0.05). Results: There was no significant difference between the degradation methods for the FBS groups. For the µTBS, the significant difference was as follows: NX 7days > NX 24h > MC 7days = MC 24h. Failure mode was mainly adhesive and mixed, but with an increase of cohesive within cement and pre-failures for the MC groups assessed by µTBS. NX had better performance than MC, regardless of the method. Conclusions: The biofilm had no effect on the materials BS and FBS test was a useful method to evaluate BS of materials with poor performance

Relationship between battery level and irradiance of light-curing units and their effects on the hardness of a bulk-fill composite resin.

Objectives: This study evaluated the relationship between the battery charge level and irradiance of light-emitting diode (LED) light-curing units (LCUs) and how these variables influence the Vickers hardness number (VHN) of a bulk-fill resin. Materials and Methods: Four LCUs were evaluated: Radii Plus (SDI), Radii-cal (SDI), Elipar Deep Cure (Filtek Bulk Fill, 3M Oral Care), and Poly Wireless (Kavo Kerr). Irradiance was measured using a radiometer every ten 20-second activations until the battery was discharged. Disks (4 mm thick) of a bulk-fill resin (Filtek Bulk Fill, 3M Oral Care) were prepared, and the VHN was determined on the top and bottom surfaces when light-cured with the LCUs with battery levels at 100%, 50% and 10%. Data were analyzed by 2-way analysis of variance, the Tukey's test, and Pearson correlations (α = 5%). Results: Elipar Deep Cure and Poly Wireless showed significant differences between the irradiance when the battery was fully charged versus discharged (10% battery level). Significant differences in irradiance were detected among all LCUs, within each battery condition tested. Hardness ratios below 80% were obtained for Radii-cal (10% battery level) and for Poly Wireless (50% and 10% battery levels). The battery level showed moderate and strong, but non-significant, positive correlations with the VHN and irradiance. Conclusions: Although the irradiance was different among LCUs, it decreased in half of the devices along with a reduction in battery level. In addition, the composite resin effectiveness of curing, measured by the hardness ratio, was reduced when the LCUs' battery was discharged.

Fit of metal-ceramic crowns: effect of coping fabrication method and veneering ceramic application

Aim: To evaluate the influence of cobalt-chromium (Co-Cr) coping fabrication methods and ceramic application on the marginal and internal fit of metal-ceramic crowns. Methods: Co-Cr copings for metal-ceramic crowns were prepared by lost wax casting or CAD-CAM machining of sintered blocks. The fit was analyzed using the silicone replica technique at four assessment points: marginal gap (MG), axial wall (AW), axio-occlusal (AO) angle, and central occlusal (CO) wall. After the initial analysis, the copings were ceramic-veneered with the layering technique, and the fit was again determined. Data were statistically analyzed by paired and unpaired Student's-t test (α=0.05). Results: Marginal and internal fit before ceramic application according to the coping manufacturing method showed significant differences only at CO (p < 0.001), with milled copings (137.98±16.71 µm) showing higher gap values than cast copings (112.86±8.57 µm). For cast copings, there were significant differences at MG (before 109.13±8.79 µm; after 102.78±7.18 µm) and CO (before 112.86±8.57 µm; after 104.07±10.63 µm) when comparing the fit before and after ceramic firing. For milled copings, there was significant difference only at AO (before 116.39±9.64 µm; after 108.54±9.26 µm). Conclusion: This study demonstrated that the coping fabrication method influenced the internal fit. Ceramic firing maintained or improved the fit of the metal-ceramic crowns. The marginal discrepancy of all restorations, before and after ceramic firing, can be considered clinically acceptable

Avaliação da sorção e solubilidade de água em cimentos de ionômero de vidro com e sem agente de proteção / Evaluation of water sorption and solubility in glass ionomer cements with and without protective agent

Objetivo: Avaliar o efeito de um protetor de superfície na sorção e solubilidade de cimentos de ionômero de vidro. Materiais e Métodos: Quatro materiais foram selecionados: ionômero modificado por resina encapsulado (Riva Light Cure); modificado por resina pó/líquido (Vitremer); convencional encapsulado (Equia Forte) e convencional pó/líquido (Fuji IX). Foram confeccionados 20 espécimes de cada, sendo metade com proteção superficial do Equia Forte Coat. As amostras foram mantidas em estufa a 37°C em repouso por 5 dias. Em seguida, esses foram pesados em intervalos de 24 horas. A espessura e o diâmetro foram medidos com um paquímetro digital para o cálculo do volume. Novas pesagens foram realizadas para a obtenção da massa intermediária. Em seguida, as amostras foram mantidas em repouso por 5 dias a 37°C e realizada nova pesagem. Resultados: Os dados obtidos de sorção e solubilidade foram submetidos à análise de variância (ANOVA dois fatores, material e protetor de superfície) e teste Tukey ( =0,05). Para sorção, houve diferença significativa apenas para o fator material (p<0,05), Vitremer > Equia Forte > Riva Light Cure > Fuji IX. O ionômero Fuji IX apresentou os menores valores de sorção, diferindo significativamente dos demais materiais, independentemente do uso do protetor superficial. Não houve diferença significativa para o fator proteção de superfície (p>0,05). Para solubilidade não houve diferença significativa no fator material, protetor de superfície ou interação material*protetor. Conclusão: O uso do protetor superficial não influenciou nos valores de sorção e solubilidade dos ionômeros avaliados e o ionômero convencional Fuji IX apresentou menores taxas de sorção.

Objective: evaluate the effect of a surface coating agents on the sorption and glass ionomer cements solubility. Materials and Methods: Four materials were selected: Encapsulated resin-modified ionomer (Riva Light Cure); Powder/liquid Encapsulated resin-modified (Vitremer); Encapsulated conventional (Equia Forte) and powder/ liquid conventional (Fuji IX). Twenty samples of each were made, half with surface protection of Equia Forte Coat. The samples were kept in an oven for 5 days. These were then weighed at 24-hour intervals. The thickness and diameter were measured using a digital caliper to calculate their volume. New weightings were performed to obtain the intermediate mass. Then, the samples were kept at rest for 5 days and weighed again. Results: The sorption and solubility data obtained were subjected to analysis of variance (two-way ANOVA, material and surface coating agents) and Tukey test ( =0.05). For sorption, there was a significant difference only for the material factor (p<0.05), Vitremer > Equia Forte > Riva Light Cure > Fuji IX. The Fuji IX ionomer showed the lowest sorption values, differing significantly from the other materials, regardless of the use of surface coating agents. There was no significant difference for the surface protection factor (p>0.05). For solubility there was no significant difference for the material factor, surface coating agents or material*surface coating agent interaction. Conclusion: The use of surface coating agents did not influence the sorption and solubility values of the evaluated ionomers and the conventional Fuji IX ionomer showed lower sorption rates.

Do tooth-supported zirconia restorations present more technical failures related to fracture or loss of retention? Systematic review and meta-analysis.

OBJECTIVES: This systematic review was performed to determine the main cause of technical failure of tooth-supported zirconia crowns and fixed partial dentures (FPDs), categorizing them as fracture/chipping or loss of retention/decementation. MATERIALS AND METHODS: Electronic and manual searches were performed for randomized clinical trials, prospective clinical trials, and prospective cohort studies that reported the technical failure rates of zirconia restorations. The Cochrane Collaboration risk-of-bias tool and Newcastle-Ottawa scale were used to assess the quality of the studies. RESULTS: Fifty-two studies were included and most of them had unclear risk of bias. Considering all reported fractures/chipping, for veneered crowns with 1 to 3 years of follow-up, the relative risk (RR) of fracture in relation to loss or retention was 3.95 (95% CI 1.18-13.23; p = 0.03). For 4 to 6 years of follow-up, the RR was 5.44 (95% CI 1.41-20.92; p = 0.01). For veneered FPDs with 1 to 3 years of follow-up, the RR was 5.98 (95% CI 2.31-15.01; p = 0.0002). For 4 to 6 years of follow-up, the RR was 3.70 (95% CI 1.63-8.41; p = 0.002). For 7 years or more of follow-up, the RR was 3.45 (95% CI 1.84-6.46; p = 0.0001). When only framework fractures were considered, there were no significant differences for the RR in all follow-up periods (p > 0.05). CONCLUSIONS: Higher RR for fracture/chipping in relation to decementation for veneered zirconia crowns and FPDs at all follow-up times. For framework fractures, no difference was observed between the risk of failure of the restoration due to fracture or decementation. CLINICAL RELEVANCE: Zirconia crowns and FPDs showed relatively high success and survival rates. However, considering the technical failures, there is approximately four times higher chance of fracture/chipping than loss of retention for both single and multi-unit tooth-supported veneered zirconia restorations.

Implant Osseointegration in Grafted Autogenous Bone Blocks Fixed with Screws and Cyanoacrylate-Based Adhesive: Histomorphometric and Micro-CT Analyses.

PURPOSE: To evaluate implant osseointegration in grafted autogenous bone blocks fixed with cyanoacrylate-based adhesive and screws. Also, grafted bone fixed either with an adhesive or screw was evaluated. MATERIALS AND METHODS: Two surgical defects in the parietal region of rabbits (n = 12) were performed in each animal. Autogenous bone blocks obtained were fixed anteriorly with a screw or cyanoacrylate-based adhesive. After 30 and 45 days of grafting procedures, implants were placed in bone blocks. Histomorphometric and microcomputed tomography (micro-CT) analyses of the implant area were performed at 30 days after implant surgery in the screw (n = 6) and adhesive (n = 6) groups. Histomorphometric analyses of bone-grafted areas were performed at 60 and 75 days in the screw (n = 6) and adhesive (n = 6) groups. Histomorphometric evaluations were carried out in implant and grafted bone areas. The micro-CT parameters evaluated were bone-to-implant contact, bone area fraction occupancy, bone volume fraction, trabecular thickness, trabecular separation, and trabecular number. RESULTS: No differences were observed in the micro-CT parameters for the screw and adhesive groups in all experimental periods. However, an increased quantity of immature bone volume was observed on the adhesive group in the grafted area after 75 days. The grafted area in the screw group (75 days) presented a decrease in the volume density of the immature bone compared with the screw group (60 days). There were no differences in both groups and experimental periods in soft tissue in the grafted area. CONCLUSION: No differences were observed in the osseointegration of implants placed in grafted autogenous bone blocks fixed with cyanoacrylate-based adhesive and screws. Therefore, osseointegration in autogenous bone fixed with cyanoacrylate-based adhesive is viable.

In-office dental bleaching with violet light emitting diode: bleaching efficacy and pulpal temperature rise.

Objectives: This study evaluated the bleaching efficacy of different in-office protocols associated with violet light emitting diode (V-LED), and measured the pulpal temperature rise caused by V-LED with or without gel application. Materials and Methods: Bovine incisors were distributed in 4 groups (n = 10): VL - V-LED; HP - 35% hydrogen peroxide (control); HYB - hybrid protocol, V-LED applied without gel for 10 irradiation cycles followed by V-LED applied with gel for another 10 irradiation cycles; and HPVL - gel and V-LED applied for 20 irradiation cycles. Three bleaching sessions were performed with 7-day intervals. Bleaching efficacy was evaluated with Δ E a b * , ΔE 00 and ΔWID . Data were recorded at baseline, 7, 14, 21 and 70 days. For pulpal temperature rise, thermocouples were placed inside the pulp chamber of human incisors. To determine intrapulpal temperature, the teeth were irradiated with V-LED with or without application of bleaching gel. Color difference data were analyzed by 2-way repeated measures ANOVA and Tukey's test. Pulpal temperature was analyzed by t-test (α = 5%). Results: VL exhibited lower color ( Δ E a b * and ΔE 00) and whiteness changes (ΔWID ) than the other groups. HPVL presented higher color change values than HYB. HYB and HPVL showed not different ΔWID values; and HP showed the highest whiteness changes at all times. There were significant differences comparing ΔT with gel (8.9°C) and without gel application (7.2°C). Conclusions: HPLV was more efficient than HYB. The 2 protocols with VL showed similar results to control. Gel application combined with VL promoted higher pulpal temperature than to the no gel group.

Effects of local single dose administration of parathormone on the early stages of osseointegration: A pre-clinical study.

The present study aimed to evaluate the effect of parathormone (PTH) administered directly to the implant's surface prior to insertion, using a large translational animal model. Sixty titanium implants were divided into four groups: (i) Collagen, control group, where implants were coated with Type-I Bovine-collagen, and three experimental groups, where implants received varying doses of PTH: (ii) 12.5, (iii) 25, and (iv) 50 µg, prior to placement. Fifteen female sheep (~2 years old, weighing ~65 kg) received four implants in an interpolated fashion in C3, C4 or C5 vertebral bodies. After 3-, 6- and 12-weeks, samples were harvested, histologically processed, qualitatively and quantitatively assessed for bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). BIC yielded lower values at 6-weeks for 50 µg relative to the control group, with no significant differences, when compared to the 12.5- and 25-µg. No significant differences were detected at 6-weeks between collagen, 12.5- and 25-µg groups. At 3- and 12-weeks, no differences were detected for BIC among PTH groups. With respect to BAFO, no significant differences were observed between the control and experimental groups independent of PTH concentration and time in vivo. Qualitative observations at 3-weeks indicated the presence of a more mature bone near the implant's surface with the application of PTH, however, no significant differences in new bone formation or healing patterns were observed at 6- and 12-weeks. Single local application of different concentrations of PTH on titanium implant's surface did not influence the osseointegration at any time-point evaluation in low-density bone.

Is the clinical performance of composite resin restorations in posterior teeth similar if restored with incremental or bulk-filling techniques? A systematic review and meta-analysis.

OBJECTIVES: A systematic review was performed to analyze the clinical performance of class I and II restorations in posterior teeth placed with the incremental or the bulk-filling techniques. The primary outcome was retention/fracture rate, and the secondary outcomes evaluated were anatomical form, surface texture, color match, marginal adaption, marginal discoloration, caries, and postoperative sensitivity. METHODS: Electronic and manual searches were performed for randomized clinical trials comparing the clinical performance of composite resin restorations in posterior teeth placed with the incremental or the bulk-filling techniques. The Cochrane Collaboration risk of bias tool was used to assess the quality of the studies and the GRADE tool was used to access the quality of the evidence. RESULTS: Fourteen studies were included in this systematic review and most of them had unclear risk of bias. The risk difference (RD) for retention/fracture was 0.00 (95%CI = - 0.01, 0.01; p = 0.86) for 1-1.5 years of follow-up; 0.00 (95%CI = - 0.02, 0.02; p = 0.88) for 2-3 years of follow-up; 0.05 (95%CI = - 0.08, 0.18; p = 0.46) for 5 or more years of follow-up. The RD for postoperative sensitivity was 0.04 (95%CI = - 0.02, 0.10; p = 0.18) for up to 30 days; 0.00 (95%CI = - 0.01, 0.02; p = 0.63) for 1-1.5 years of follow-up; and 0.00 (95%CI = - 0.01, 0.02; p = 0.71) for 2-3 years of follow-up. For the other secondary outcomes, no significant differences were observed (p > 0.05) between the restorative techniques. The certainty of evidence was graded as moderate. CONCLUSIONS: The clinical performance of class I and II restorations in posterior teeth is similar when placed with the incremental and bulk-filling techniques. CLINICAL RELEVANCE: Based on the results of this study, posterior restorations placed with bulk-filling technique present satisfactory clinical performance, which is similar to direct restorations placed with the conventional incremental technique, considering various follow-up periods evaluated. TRIAL REGISTRATION:  CRD42018108450.

Effect of processing methods on the chipping resistance of veneered zirconia.

OBJECTIVES: To evaluate the edge chipping resistance (ReA) and the fracture toughness (KC) of 3Y-TZP bilayers produced with the following materials/processing combinations: fluorapatite glass-ceramic applied on zirconia using the traditional layering and hot-pressing (press-on) techniques; feldspathic porcelain using rapid layer technology (RLT); and lithium disilicate glass-ceramic using CAD-on method. The influence of the cooling rate (slow and fast) was analyzed for layering and hot-pressing. METHODS: Bilayer bars (25x4x2 mm) were made following manufacturers' instructions. The edge chipping test was performed in an universal testing machine, using a coupled Vickers indenter. ReA was calculated dividing the critical load at fracture by the edge distance. Fracture toughness was calculated by a regression fit with a fixed slope of 1.5 correlating the critical chipping load regarding edge distance and also with indentation fracture (IF) method. Data were statistically analyzed using ANOVA and Tukey's test (α = 5%). RESULTS: ReA and KC was significantly higher for the CAD-on bilayers. RLT showed intermediate ReA means, and layering and hot-pressing techniques showed the lowest ReA values. For both processing methods there was no effect of the cooling protocol on the ReA and fracture toughness. CONCLUSIONS: There is a significant effect of the material/processing association on the edge chipping resistance and fracture toughness of the bilayers. There was no effect of the cooling protocol on the edge chipping resistance and fracture toughness for the specimens processed by both the layering and hot-pressing techniques.

Influence of two carbodiimides on the bond strength of universal adhesives to dentin.

The pretreatment of dentin with cross-linking agents during bonding procedures has been proposed to improve the mechanical properties of the collagen in the hybrid layer and reduce the biodegradation of the adhesive interface. The aim of this study was to evaluate the influence of pretreatment with two carbodiimides on the dentin bond strength of universal adhesives, after thermocycling. Three universal adhesives in the self-etching mode were used (Single Bond Universal-SBU, Clearfil Universal-CLU and Ambar Universal-ABU). A self-etching adhesive system (Clearfil SE Bond-CSB) was used as control. Two carbodiimides, 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide (EDC) and N,N'-dicyclohexylcarbodiimide (DCC), were applied for 1 min. The excess solution was removed with absorbent paper and the universal adhesives were applied. The specimens were stored for 24 h in distilled water at 37 °C or 10,000 thermal cycles (5-55 °C, 30 s) and then were prepared for microtensile bond strength test (n = 4 teeth, average of 21 sticks per group). Data were analyzed using three-way ANOVA and Tukey's (α = 5%). After 24 h, SBU and CSB had statistically similar bond strength values for the control groups (22.07 ± 9.03 and 19.82 ± 7.28 MPa), with EDC (30.21 ± 11.30 and 19.67 ± 5.36 MPa) and DCC (30.12 ± 13.43 and 19.82 ± 7.28 MPa) pretreatments (p > 0.05). The use of EDC (32.57 ± 9.60 MPa) and DCC (24.71 ± 9.87 MPa) showed statistically higher bond strength for CLU than for the control group (14.62 ± 6.16 MPa; p < 0.05). After thermocycling, the SBU, CLU, and CSB groups showed statistically similar bond strengths with the use of EDC (27.08 ± 8.44; 18.74 ± 5.41; and 24.55 ± 10.43 MPa) and without the use of cross linkers (20.06 ± 7.99; 22.55 ± 9.04; and 26.54 ± 10.13 MPa; p > 0.05). Groups tested after 24 h in distilled water presented higher bond strength than those submitted to thermocycling. It can be concluded that the use of cross linkers influenced the immediate bond strength of the universal adhesives, and this was dependent on the combination of the adhesive system and type of carbodiimide. The use of EDC increased the immediate bond strength of CLU. DCC increased the bond strength of ABU at 24 h, but the values were lower than those of the control group after aging for three out of the four adhesives.

Effect of MDP concentration and addition of iodonium salt on the dentin bond strength of experimental adhesives / Efeito da concentração de MDP e adição de sal de iodônio na resistência de união à dentina de adesivos experimentais

Objetivo: O objetivo foi avaliar a resistência de união de seis adesivos experimentais contendo sistemas fotoiniciadores binários ou ternários, associados a três diferentes concentrações de MDP (0-12% em peso) após 12 meses de armazenamento em água destilada. Material e Métodos: Adesivos experimentais foram preparados com: bis-GMA, UDMA, bis-EMA, TEGDMA, HEMA, BHT e etanol, contendo sistemas fotoiniciadores binários (CQ/amina) ou ternários (CQ/amina/DPIHFP ­ 0,5% em peso). Foi adicionado a esta composição 0%, 6% ou 12% em peso de MDP. Os sistemas adesivos foram aplicados seguindo o protocolo com condicionamento ácido. Moldes cilíndricos transparentes foram colocados sobre a dentina hibridizada, preenchidos com resina composta e fotopolimerizados. Os corpos-de-prova foram armazenados em água destilada a 37oC por 24h ou 12 meses e submetidos ao ensaio de microcisalhamento (n=6). Os dados foram analisados por ANOVA de três fatores e teste de Tukey (α=5%). Resultados: Para o sistema binário, após 12 meses de armazenamento, todos os valores de resistência de união foram semelhantes. Em relação à degradação da resistência de adesão ao longo do tempo, as formulações de MDP de 6% e 12% mostraram resistência de união mais estável do que 0% de MDP. Para o sistema ternário, todas as formulações (0%, 6% e 12% em massa de MDP) mostraram resistência de união estável em função do tempo. Conclusão: Para o sistema binário, as concentrações de 6 e 12% em massa de MDP foram capazes de manter a resistência de união em função do tempo, enquanto que para o sistema ternário, a estabilidade de união foi obtida independentemente da concentração de MDP. Pode-se concluir que, para a formulação dos adesivos utilizados neste estudo, independente do sistema fotoiniciador, a concentração de 12% MDP apresentou valores de resistência de união mais estáveis após 12 meses de armazenamento em água (AU)

Objective: The aim was to evaluate the bond strength of six experimental adhesives containing binary or ternary photoinitiator systems, associated with three different MDP concentrations (0-12wt%) after 12 months of storage in distilled water. Material and Methods: Experimental adhesives were prepared with: bis-GMA, UDMA, bis-EMA, TEGDMA, HEMA, BHT, and ethanol, containing binary (CQ/amine) or ternary (CQ/amine/DPIHFP (diphenyliodonium hexafluorophosphate) ­ 0.5wt%) photoinitiator systems. It was added to this composition 0wt%, 6wt%, or 12wt% of MDP. The adhesive systems were applied following the etch-and-rinse protocol. Transparent cylindrical molds were placed on the hybridized dentin, filled with composite resin and light-cured. The specimens were stored in distilled water at 37oC for 24h or 12 months and submitted to a microshear bond strength test (n=6). Data were analyzed by three-way ANOVA and Tukey's test (α=5%). Results: For the binary system, after 12 months of storage, all bond strength values were similar. Regarding bond strength degradation over time, 6wt% and 12wt% MDP formulations showed more stable bond strength than 0wt% MDP. For the ternary system, all formulations (0wt%, 6wt% and 12wt%) showed stable bond strength over time. Conclusion: For the binary photoinitiator system, the 6wt% and 12wt% MDP concentrations were able to keep bond strength stable over time, while for the ternary system, bond strength stability was achieved regardless the MDP concentration. (AU)

Effect of Age and Sodium Alendronate on Femoral Fracture Repair: Biochemical and Biomechanical Study in Rats.

BACKGROUND: Bisphosphonates are drugs widely used to reduce bone resorption, increase bone mineral density and control age-related bone loss. Although there are studies reporting differences in bone structure between young and old adults, it is still difficult to predict changes related to bone aging. The aim of this study was to evaluate the effect of age and sodium alendronate on bone repair of femoral fractures in rats. METHODS: Wistar rats (n = 40) were allocated into groups: O (control old-rats), Y (control young-rats), OA (alendronate old-rats) and YA (alendronate young-rats). All animals underwent linear fracture surgery followed by fixation. Groups OA and YA received 1 mg/kg alendronate three times a week until euthanasia. Biochemical analysis of calcium and alkaline phosphatase was done. After euthanasia, femurs were evaluated in relation to cross-section and flexural strength, with three-point bending test. Data were submitted to statistical analysis with significance level of 0.05. RESULTS: There was no difference in calcium and alkaline phosphatase levels (p > 0.05). Young animals presented lower cross-section than older animals (p < 0.05). Only fractured side, young animals presented major flexural strength than older animals (p < 0.05). There was no difference between the animals that used or not alendronate in relation to cross-section and flexural strength (p > 0.05). When compared fractured and non-fractured femurs, major cross-section on fractured side was observed (p < 0.05). Flexural strength presented higher values in femurs on non-fractured side (p < 0.05). There was correlation of weight and cross-section (R = +0.91) and weight with flexural strength of fractured and non-fractured side, respectively (R = -0.97 and -0.71). CONCLUSION: In short, there was no difference of calcium and alkaline phosphatase during the bone repair process. Age has influence in cross-section and flexural strength. Alendronate showed no association with these factors.

Retrospective clinical and radiographic evaluation of restored endodontically treated teeth.

OBJECTIVES: The aim of this study was to perform a clinical and radiographic analysis of endodontically treated teeth (ETT) restored with cast metal posts (CMPs) or prefabricated glass fiber posts (GFPs) and crowns. MATERIALS AND METHODS: Fifty ETT were restored with 25 CMPs and 25 GFPs at a private dental clinic between 2001 and 2016. The restorations consisted of 12 all-ceramic crowns, 31 metal-ceramic crowns, and 7 composite resin crowns. Demographic data, type of teeth, type of post-and-core system, time of placement, crown restorations, the number of proximal contacts, the type of antagonist, and reports of any complications after post-and-core placement were recorded for each patient. Assessments were performed at baseline (radiographic) and follow-up (radiographic and clinical). Data were analyzed by the McNemar test, the Pearson χ2 test, and Kaplan-Meier survival curves (α = 0.05). The mean follow-up was 67.6 months. RESULTS: No significant difference was observed for any of the radiographic parameters when the baseline and final radiographs were compared. In the clinical evaluation, anatomical form (p = 0.009) and occlusion (p = 0.001) showed significant differences according to the type of crown restoration; specifically, metal-ceramic and all-ceramic crowns outperformed composite resin crowns. CONCLUSIONS: CMPs and GFPs showed favorable results for restoring ETT after 6 years of follow-up. All-ceramic and metal-ceramic crowns showed higher survival rates and better clinical outcomes.

Descoloração da coroa após obturação endodôntica com diferentes cimentos: estudo clínico / Crown discoloration after endodontic obturation with different cements: a clinical study

Objetivo: O objetivo do presente estudo foi avaliar clinicamente a descoloração da coroa dentária após obturação do canal radicular com diferentes cimentos endodônticos. Métodos: Trinta e dois dentes foram tratados endodonticamente e obturados com AH Plus (AHP), Endofill (END), MTA Fillapex (MTA) ou Sealer 26 (SEA), divididos em oito pacientes por grupo. O registro das cores foi realizado com um espectrofotômetro antes da intervenção (T0 ), aos 30 (T1 ) e aos 90 dias após a intervenção (T2 ). As avaliações foram feitas no centro da coroa dentária e a variação de cor (ΔE) foi calculada por meio da Commission International de l'Eclai- rage (CIE) L*a*b. Um operador, especialista em Endodontia, realizou os procedimentos clínicos. Os dados foram submetidos a medidas repetidas ANOVA e teste de Tukey (Δ=5%). Resultados: Não houve diferença estatisticamente significativa na variação de cores entre os cimentos (AHP ΔE=4,11; END ΔE = 6,34; SEA ΔE = 8,77 e MTA ΔE = 12,15), p>0,05. Porém, houve diferença entre os períodos analisados (T1ΔE= 5,65; T2 ΔE = 10,02). Conclusões: Dentro das limitações deste estudo, todos os cimentos endodônticos causaram alterações cromáticas clinicamente perceptíveis na coroa dentária. No entanto, o AH Plus promoveu menos alterações cromáticas na coroa dentária (AU).

Introduction: The aim of this study was to evaluate the crown discoloration after root canal filling with different endodontic cements clinically. Methods: Thirty-two teeth were endodontically treated and filled with AH Plus (AHP), Endofill (END), MTA Fillapex (MTA), or Sealer 26 (SEA), divided into eight patients per group. Color recording was performed with a spectrophotometer before the intervention (T0 ) and at 30 (T1 ) and 90 days post-intervention (T2 ). The evaluations were done in the center of the dental crown and color variation (ΔE) was calculated by means of the Commission International de IEclairage (CIE) L*a*b. The data were subjected to repeated measures ANOVA and Tukeys test (alpha=5%). Results: There was no statistically significant difference in color variation between the cements (AHP ΔE=4.11; END ΔE=6.34; SEA ΔE=8.77, and MTA ΔE=12.15), p>0.05. However, there was a difference between the periods tested (T1 ΔE=5.65; T2 ΔE=10.02). Conclusions: All tested endodontic cements altered the color of dental crowns (AU).

Growth hormone effects on healing efficacy, bone resorption and renal morphology of rats: histological and histometric study in rat calvaria.

Previous reports demonstrated the utility of systemic application of growth hormone (GH) in the treatment of bone defects. Very few studies correlated bone repair efficacy with hepatic and renal side effects promoted by locally-delivered GH. The objectives of this study were to assess the bone repair properties along with hepatic and renal adverse effects promoted by local application of GH in a rat model. Thirty-two rats were randomly divided (4 groups; n = 8/group), as follows: (i) AB (autogenous bone + local application of saline solution [SS]), (ii) AB+ (autogenous bone + SS local application + SS irrigation), (iii) AB/GH+ (autogenous bone + SS local application + GH irrigation) and (iv) AB/GHL+ (autogenous bone + GH local application + GH irrigation). Critical-sized defects (diameter = 5.0 mm) were surgically created by a single operator in the calvaria of rats. Defects were filled with ground autogenous bone. Defects pertaining to AB+ and AB/GH+ received a mixture of autogenous bone and a SS-saturated (0.02 mL) collagen sponge covered with bovine cortical membrane. Defects in group AB/GHL+, were filled with the same biomaterials saturated with GH (0.02 mL). SS (0.1 mL) or GH (0.1 mL, equivalent to 0.4 IU) were applied locally on alternate days (8 weeks) in animals in groups AB, AB+ and AB/GH+ or AB/GHL+, respectively. Bone repair properties was determined in hematoxylin/eosin-stained slices using traditional histologic and histomorphometric techniques along with optical microscopy and digital image analysis. Statistical differences among groups was determined using Kruskal-Wallis and Tukey post hoc tests (α = 0.05). Histology results indicated that AB and AB+ displayed greater presence of autogenous bone as compared to AB/GH+ and AB/GHL+. Histomorphometric results indicated significantly higher osteoid matrix formation in AB and AB+ when compared to AB/GHL+ (p = 0.009). Kidneys and livers were found to have their glomeruli preserved in AB and AB+. Strong glomeruli necrosis and large areas of protein deposition were found in AB/GH+. Abnormal small-sized glomeruli were found in AB/GHL+. The utilization of autogenous bone graft associated with local application and irrigation with GH was shown to not improve the bone repair in calvarial critical-sized defects in a rat model.

Effect of the addition of functionalized TiO2 nanotubes and nanoparticles on properties of experimental resin composites.

OBJECTIVE: To evaluate the influence of the addition of functionalized and non-functionalized TiO2 nanostructures on properties of a resin composite. METHODS: TiO2 nanostructures were synthesized and functionalized, using 3-(aminopropyl)triethoxysilane (APTMS) and 3-(trimethoxysilyl)propyl methacrylate (TSMPM). Characterizations were performed with XRD, EDS, TEM, and TGA. Resin composites containing Bis-GMA/TEGDMA, CQ, DABE, and barium-aluminum silicate glass were produced according to TiO2 nanostructure (nanotube or nanoparticle), concentration (0.3 or 0.9 wt%), and functionalization (APTMS or TSMPM). The resin composite without nanostructures was used as control. The amount of fillers was kept constant at 78.3 wt% for all materials. The degree of conversion (DC - at 0 h and 24 h), maximum polymerization rate (Rpmax), and Knoop microhardness (KHN before and after ethanol softening) were evaluated. Data were analyzed with two-way ANOVA with repeated measures and Tukey's HSD (α = 0.05). RESULTS: TGA results demonstrated that functionalizations were effective for both nanostructures. For DC, resin composites, time and interaction effect were significant (p < 0.001). Higher DC was found for 0.3-wt%-functionalized-nanotubes at 24 h. For nanoparticles, only 0.9-wt%-non-functionalized and 0.3-wt%-APTMS-functionalized showed DC similar to the control and all other groups showed higher DC (p < 0.05). Rpmax was higher for 0.3-wt%-APTMS-nanotubes, which corresponded to higher DC after 24 h. The lowest Rpmax occurred for 0.9-wt%-TSMPM-nanotubes, which showed smaller DC at 0 h. For KHN, resin composites, ethanol softening and interaction effect were significant (p < 0.001). KHN decreased after ethanol softening all groups, except for 0.3-wt%-TSMPM-nanotubes, 0.9-wt%-TSMPM-nanotubes, and 0.3-wt%-non-functionalized-nanoparticles. CONCLUSION: The resin with 0.3-wt%-TSMPM-nanotubes showed higher DC after 24 h, while being the most stable material after the ethanol softening. SIGNIFICANCE: The addition of functionalized TiO2 nanostructures in resin-based materials may improve the properties of the material.