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1.
Am J Dent ; 34(1): 31-38, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33544986

RESUMEN

PURPOSE: To examine the marginal adaptation in enamel and dentin of mixed Class V saucer shaped restorations where cavities were prepared by two different lasers. METHODS: A handpiece-integrated Er:YAG laser @ 4.5 W, 300 mJ, 15 Hz (LiteTouch III) and a novel CO2 laser @ 12.95 W, 19.3 mJ, 671 Hz (Solea 9.3 µm). Diamond bur preparation with a 25 µm diamond bur (Intensiv) in a red contra angle at high speed under water spray cooling served as the control. Eight cavities per group were readied and restored under simulation of dentin fluid with a one bottle universal adhesive (One Coat 7 Universal) and a nanohybrid resin composite (Everglow), applied in two layers. For every preparation technique, the adhesive system was applied in the selective-etch and the self-etch mode, resulting in six experimental groups. Marginal analysis was performed immediately after polishing and after simultaneous thermal (5-50°C, 2 minutes each) and mechanical (max. 49 N; 200,000 cycles) loading by using a SEM (x200 magnification). RESULTS: Significant differences were found for all groups - except groups 2 and 5 - between initial and terminal results and between the groups as well (P< 0.05, 2-way ANOVA with Fisher's post-hoc test). The bur prepared group with selective-etch technique showed the best overall results after loading, followed by Er:YAG prepared self-etch group and CO2-prepared selective-etch group. CLINICAL SIGNIFICANCE: By using a universal one-component adhesive system, marginal adaptation in enamel and in dentin depended on the preparation method and on the adhesive's application technique as well. When using lasers, Er:YAG in self-etch mode and CO2 9.3 µm in selective-etch mode total marginal adaptation showed results which were comparable to conventional bur preparation with selective-etch technique.


Asunto(s)
Recubrimiento Dental Adhesivo , Láseres de Estado Sólido , Dióxido de Carbono , Resinas Compuestas , Preparación de la Cavidad Dental , Cementos Dentales , Dentina , Recubrimientos Dentinarios , Cementos de Resina
2.
J Adhes Dent ; 23(1): 21-34, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33512113

RESUMEN

The importance of the interdental anatomy of a class-2 direct composite restoration is one of the most underestimated topics in direct posterior composite restorations. The proximal emergence profile of the restoration and the contact area should be designed to maximize arch continuity and to minimize food impaction. Other restorative criteria that must be fulfilled are marginal adaptation compatible with the dental and periodontal integrity, and geometry of the marginal ridge compatible with the mechanical integrity of the restoration under load. Shortcomings will result in masticatory discomfort, caries, periodontal problems and undesired movement of teeth. In vitro and in vivo studies showed that the use a contoured sectional metal matrix band with a separation clamp results in the tightest contact point. However, this matrix system also has shortcomings and does not give the expected result in all class-2 cavities. The variation in depth, width of the box, distance between the cervical cavity margin and the adjacent tooth requires customization of the interproximal space. In order to realize this, sectional matrix bands with several profiles of curvature, variation of wedges and separation clamps, and the use of teflon tape are required. In addition, dentists should follow a protocol allowing them to build a proximal composite surface that fulfills the required restorative criteria. Pre-wedging, space evaluation, interproximal clearance, correct selection, positioning and stabilization of the matrix band are important steps in this protocol.


Asunto(s)
Resinas Compuestas , Restauración Dental Permanente , Preparación de la Cavidad Dental , Adaptación Marginal Dental , Bandas de Matriz
3.
J Adhes Dent ; 23(1): 67-75, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33512117

RESUMEN

PURPOSE: To investigate the fatigue performance and stress distribution of endodontically treated maxillary premolars with occlusal (O), mesio-occlusal (MO), or mesio-occluso-distal (MOD) cavities filled directly with bulk-fill composite. Materials and Methods: Besides the intact teeth (control group), sixty sound maxillary first premolars, standardized by size and morphology, were subjected to root canal treatment and randomly allocated to three groups throughout cavity preparations (O/MO/MOD). All cavities were restored with a bulk-fill composite (Tetric N-Ceram Bulk fill) and universal adhesive (Tetric N-Bond Universal) using etch-and-rinse mode. Half of the specimens of each group underwent 20,000 thermocycles (5°C-55°C). All specimens were subjected to a 50-N load perpendicular to their buccal bevels on the palatal cusps for 1,200,000 cycles. The survival curve and fracture mode were analyzed by log-rank and Fisher's exact tests, respectively. Finite element analysis (FEA) was conducted to simulate the working condition of premolars with O/MO/MOD cavities. The von Mises stress and the first principal stress were calculated for three FEA models. Results: Premolars with O cavity restorations exhibited better stress distributions than did those with MO and MOD cavity restorations. Compared to the intact premolars, no significant difference was detected in the fatigue performance of O/MO/MOD restorations, regardless of whether they underwent thermocycling. Only one specimen presented unrestorable fracture, while the rest of the fractured premolars were restorable. Conclusion: The cavity design of endodontic premolars restored with a bulk-fill composite has no influence on the stress distribution or fatigue survival, with a biomechanical performance similar to that of an intact tooth.


Asunto(s)
Fracturas de los Dientes , Diente no Vital , Diente Premolar , Resinas Compuestas , Preparación de la Cavidad Dental , Restauración Dental Permanente , Análisis del Estrés Dental , Humanos
4.
Oper Dent ; 45(6): 664-676, 2020 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-32997740

RESUMEN

CLINICAL RELEVANCE: When a resin nanoceramic inlay is cemented using self-adhesive cement, a universal dentin adhesive can be applied to the prepared cavity. The application of the adhesive before self-adhesive cement placement provides similar or better interfacial adaptation than without the adhesive. SUMMARY: Purpose: The first objective of this study was to determine whether the luting material used for computer-aided design and computer-aided manufacture resin nanoceramic inlays affected interfacial adaptation. The second objective was to investigate whether application of a universal dentin adhesive before cementation affected interfacial adaptation. The final objective was to compare the inlay-side and dentin-side interfaces in the cement space.Methods and Materials: Seventy-four class I cavities were prepared on extracted human third molars. Cavities were optically scanned, and resin nanoceramic inlays were milled using Lava Ultimate blocks (3M ESPE). For the control groups, the fabricated inlays were cemented using Panavia V5 (Kuraray Noritake) or FujiCem 2 (GC). For the experimental groups, the teeth were randomly divided into groups I and II. Group I contained four subgroups using different luting materials; in all subgroups, the inlays were cemented and dual cured without pretreatment. Group II contained six subgroups in which inlays were cemented and dual cured after application of a universal dentin adhesive. After thermocycling, interfacial adaptation was measured using swept-source optical coherence tomography (SS-OCT) imaging and statistically compared among groups.Results: Interfacial adaptation was different depending on the luting material used (p<0.05). After application of a universal adhesive, some subgroups showed improved interfacial adaptation (p<0.05). In the comparison of inlay-side and dentin-side interfaces, no difference was found in interfacial adaptation (p>0.05).Conclusions: Interfacial adaptation for resin nanoceramic inlays differed with luting material. For some self-adhesive cements, application of a universal adhesive before cementation improved interfacial adaptation.


Asunto(s)
Incrustaciones , Tomografía de Coherencia Óptica , Resinas Compuestas , Diseño Asistido por Computadora , Preparación de la Cavidad Dental , Porcelana Dental , Humanos , Ensayo de Materiales , Cementos de Resina
5.
Am J Dent ; 33(4): 201-205, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32794395

RESUMEN

PURPOSE: To evaluate the effect of bacterial exposure on the marginal integrity of dentin-resin interfaces for composites with and without bioactive glass (BAG). METHODS: Cavity preparations of 5 mm width and 1.5 mm depth were machined into dentin disks by means of a computer controlled milling system. After applying the bonding agent, cavity preparations (n=3-5) were restored by incremental technique with experimental resin composites (50:50 BisGMA/TEGDMA: 72wt% filler) with different filler compositions: control - 67 wt% silanated strontium glass and 5wt% aerosol-silica filler and BAG - 57 wt% silanated strontium glass and 15 wt% BAG-65 wt% silica. Samples were then stored in sterile Todd-Hewitt media or co-incubated with Streptococcus mutans (UA 159), at 37°C, 5% CO2 for 1-2 weeks. For samples co-incubated with a living biofilm, a luciferase assay was performed in order to assess its viability. Surfaces were impressed before and after each storage condition and replicas examined in a scanning electron microscope. Using image analysis software (Image J), the discontinuous margins percentage (%DM) was quantitatively assessed. Data were analyzed using two-way ANOVA followed by Tukey's test (α= 0.05). RESULTS: Gap size ranged between 7-23 µm. The bacterial exposure significantly increased the %DM in both groups predominantly due to the formation of new gap regions. There was no difference between control and BAG composites regarding %DM and the biofilm viability. Bacterial exposure promoted degradation of composite restoration marginal integrity, with no difference between composites with and without BAG. CLINICAL SIGNIFICANCE: The samples incubated with living biofilm had a higher gap percentage in the margins, confirming the negative effect of cariogenic bacteria on margin degradation. The parameters defined for such synergy can help to understand the multi-factorial aspect of marginal discontinuity and therefore, predict the behavior of composite restorations subjected to the challenging oral environment.


Asunto(s)
Resinas Compuestas , Preparación de la Cavidad Dental , Biopelículas , Adaptación Marginal Dental , Restauración Dental Permanente , Vidrio , Microscopía Electrónica de Rastreo , Streptococcus mutans
6.
Cient. dent. (Ed. impr.) ; 17(2): 115-120, mayo-ago. 2020. ilus, tab
Artículo en Español | IBECS | ID: ibc-195099

RESUMEN

INTRODUCCIÓN: el tratamiento de conductos produce cambios físico-químicos en la dentina y una pérdida estructural significativa para el diente, lo que lo hace más susceptible a la fractura. MATERIAL Y MÉTODOS: 64 premolares mandibulares fueron decoronados y divididos aleatoriamente en cuatro grupos (n = 16): grupo control (CG) no tratado, grupo instrumentado ProTaperGold® (PTG®) (25.08), grupo instrumentado ProTaperNext® (PTN®) (25.06) y grupo instrumentado WaveOne Gold PRIMARY® (WOG®) (25.07). Durante la instrumentación, se realizó la irrigación con NaOCl al 5,25% con una jeringa Monoject® y tras la instrumentación, las muestras se irrigaron con NaOCl, EDTA 17% y NaOCl activado sónicamente. Los conductos radiculares se obturaron utilizando el sistema B&L®, y posteriormente se colocaron en bloques de resina acrílica estandarizados para ser cargados con una fuerza vertical constan-te de 0,02 mm/s hasta que se produjo la fractura de la raíz, mediante una máquina de ensayo universal (ME-405/20, Servo-sis®). Las comparaciones entre grupos se analizaron con la prueba ANOVA.RESULTADOS: No hubo diferencias esta-dísticamente significativas (p > 0,05) entre el GC y los grupos instrumentados con PTN® y WOG®; tampoco entre los grupos PTN® y WOG®. Sin embargo, se obtuvieron diferencias estadísticamente significativas entre el grupo instrumentado con PTG® y el resto de los grupos, siendo el grupo PTG® el más susceptible a la frac-tura. CONCLUSIONES: El sistema PTG® fue el que más debilitó las raíces después de la instrumentación, en comparación con los sistemas WOG® y PTN®


INTRODUCTION: root canal treatment produces physicist-chemist changes in the dentine and a significant structural loss for the tooth what makes it more susceptible to fracture. MATERIAL AND METHODS: 64 mandibular premolar were decoronated and randomly divided into four groups (n = 16): control group (CG) non-treated, ProTaper Gold(TM) (PTG(TM)) instrumented group (25.08), ProTaper Next(TM) (PTN(TM)) instrumented group (25.06) and WaveOne Gold(TM) PRIMARY (WOG(TM)) instrumented group (25.07). While shaping, cleaning was done with NaOCl 5,25% using a Monoject(TM) syringe and after shaping, roots were irrigated with NaOCl, EDTA 17% and NaOCl sonically activated. Root canals were obturated using B&L(TM) system, embedded into standardized acrylic resin blocks and load with a constant vertical force of 0,02 mm/s until root fracture was produced using a universal testing machine (ME-405/20, Servosis(TM)). Comparisons among groups were analyzed with ANOVA test. RESULTS: There were no statistically significant differences (p > 0.05) between the CG and the groups instrumented with PTN(TM) and WOG(TM); neither among PTN(TM) and WOG(TM) groups. However, statistically significant differences were obtained between the group instrumented with PTG(TM) and the rest of the groups being PTG(TM) group the most susceptible to fracture. CONCLUSIONS: PTG(TM) system was the one that weakened more the roots after the instrumentation in comparison with the WOG(TM) and PTN(TM) systems


Asunto(s)
Humanos , Preparación de la Cavidad Dental/métodos , Fracturas de los Dientes/etiología , Fracturas de los Dientes/terapia , Diente Premolar/lesiones , Preparación del Conducto Radicular/instrumentación , Materiales de Obturación del Conducto Radicular/uso terapéutico , Restauración Dental Permanente/métodos , Análisis de Varianza , Irrigantes del Conducto Radicular/uso terapéutico
7.
J Endod ; 46(12): 1849-1855, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32721484

RESUMEN

INTRODUCTION: The aim of this investigation was to determine the coronal strain variations in mandibular molars under an in vivo bite load after root canal treatment procedures. METHODS: The coronal strain in carious mandibular first molars with symptomatic irreversible pulpitis (experimental group) was compared with that of intact contralateral teeth (control group) in patients 20-40 years old. Experiments were conducted in 2 stages. In stage 1, the maximum bite force on the first molar region was determined on the experimental and control teeth using a customized load cell. In stage 2, strain gauges were bonded to the buccal aspect of teeth, and the strain was recorded after the application of a bite load on the intact (control) teeth; and the experimental teeth before and after endodontic access cavity preparation, cleaning/shaping procedures, root filling, and composite core restoration. RESULTS: The mean maximum bite force on the experimental teeth (91 ± 48 N) and the contralateral control teeth (91 ± 49 N) was not significantly different (P = .989). The preoperative strain (microstrain) in the experimental teeth was significantly higher (125 ± 36, P = .001) than in the contralateral intact teeth (46 ± 17). Access cavity preparation significantly increased the strain (327 ± 98, P = .019) on the experimental teeth compared with the preoperative strain. Cleaning/shaping (355 ± 113) and root filling (346 ± 89) did not significantly increase (P = 1.00) the strain compared with the strain determined after endodontic cavity preparation. Composite core restoration in the experimental teeth (106 ± 41) resulted in a significant reduction in the strain compared with the values recorded after an endodontic access cavity (P = .002) and was similar to the preoperative strain values (P = 1.00) but was significantly higher than the strain values in contralateral intact teeth (P = .001). CONCLUSIONS: The coronal strain on the buccal surface of mandibular first molars significantly increased with access cavity preparation, which did not increase further after cleaning/shaping or root filling. A significant reduction in the strain induced by root canal treatment steps was evident after composite core restoration.


Asunto(s)
Cavidad Pulpar , Diente Molar , Adulto , Fuerza de la Mordida , Preparación de la Cavidad Dental , Humanos , Diente Molar/cirugía , Tratamiento del Conducto Radicular , Adulto Joven
8.
Oper Dent ; 45(5): E227-E236, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32502270

RESUMEN

CLINICAL RELEVANCE: Using a material that optimizes marginal seal when using a margin elevation technique to manage deep class II cavities should enhance clinical outcomes. SUMMARY: Objectives: The purpose of this laboratory study was to perform a tridimensional interfacial gap evaluation of class II cavities with enamel and dentin cervical margins, before and after cyclic fatigue, restored with different nanohybrid resin composites.Methods and Materials: Standardized class II cavities were performed on 48 intact maxillary premolars, placing the mesial cervical margin 1 mm above the cement-enamel junction (CEJ) and the distal cervical margin 1 mm below the CEJ. Specimens were treated with two-step self-etch adhesive (Clearfil SE Bond2) and divided into six groups according to the restoration technique. Microcomputed Tomography imaging was executed before and after 1,000,000 cycles of chewing simulation at 50 N. Tridimensional interfacial gaps, expressed as cubic millimeters, were analyzed through a standardized software flowchart (Mimics). Data were analyzed with a two-way analysis of variance and Tukey post hoc tests (α=0.05).Results: Restoration technique (p=0.001) and chewing simulation (p=0.00001) significantly influenced interfacial gap on dentin but not on enamel. The post hoc test showed that, on dentin margins, flowable resins had a lower gap at baseline but a higher gap after chewing simulation, especially when a 2-mm-thick layer was applied, compared with nanohybrid and bulk-fill composites.Conclusions: Based on the obtained results, no differences in interfacial gap volume were found on enamel margins. On dentin margins, flowable resins showed better marginal seal at baseline, but they seem to be more prone to interfacial degradation during chewing simulation than traditional composites.


Asunto(s)
Resinas Compuestas , Restauración Dental Permanente , Preparación de la Cavidad Dental , Adaptación Marginal Dental , Materiales Dentales , Cementos de Resina , Programas Informáticos , Microtomografía por Rayos X
9.
Niger J Clin Pract ; 23(6): 798-804, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32525114

RESUMEN

Aims: The aim of this study was to evaluation the treatment success of the short post technique (mushroom restoration) using a composite resin in severely decayed primary anterior teeth after 6, 12, and 18 months after treatment. Methods: Eighteen children aged 3-5 years with severely decayed primary maxillary anterior teeth (60 anterior maxillary primary teeth in total) were included. Patients were treated under general anesthesia (GA). After pulpectomy, a "mushroom shape" was formed in the root canals for the purpose of retention, and the root canals were filled with zinc oxide-eugenol (ZOE), and the teeth were restored with composite resin. The status of treatment was evaluated clinically and radiographically for periapical radiolucency, pathological root resorption, marginal fracture, and loss of restoration for each treated tooth. All findings were recorded. Results: As a result of the evaluation criteria, the success rates at 6, 12 and 18 months were 86%, 80%, and 71%, respectively. None of the teeth showed apical radiolucency or pathological root resorption at the end of the 18th month period. Conclusion: The short-post (mushroom restorations) technique is a clinically acceptable alternative method for restoration of severely decayed primary teeth. This study supports the feasibility of treatment with this technique for pediatric patients treated under GA.


Asunto(s)
Restauración Dental Permanente/métodos , Técnica de Perno Muñón , Pulpectomía/métodos , Materiales de Obturación del Conducto Radicular/uso terapéutico , Diente Primario/cirugía , Cemento de Óxido de Zinc-Eugenol/uso terapéutico , Anestesia General , Preescolar , Resinas Compuestas/química , Caries Dental/complicaciones , Preparación de la Cavidad Dental , Extravasación de Materiales Terapéuticos y Diagnósticos/complicaciones , Femenino , Humanos , Masculino , Maxilar , Pulpectomía/efectos adversos , Resorción Radicular , Traumatismos de los Dientes/complicaciones , Resultado del Tratamiento
10.
J Endod ; 46(9): 1286-1290, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32553875

RESUMEN

INTRODUCTION: Ultraconservative access cavities (UCACs) have been proposed to reduce crown weakening, but there is no consensus about their design and size and about their advantages and disadvantages, which are also related to how differently they are performed. The purpose of the present study was to evaluate the possible use of a novel Dynamic Navigation System (DNS) in planning and executing UCACs and its precision in vitro, compared with a manual approach (MA) without any guide. METHODS: Twenty radiopaque, artificial teeth replicas were randomly divided into 2 identical groups and scanned using cone-beam computed tomography. In the first group (MA) MB1 canal orifice was reached, starting from the central part of the molar occlusal surface, using a micro endodontic bur. In the second group, DNS allowed to plan and execute a more direct, straight-line truss access. After cavity preparation, teeth were scanned again, and cone-beam computed tomography images were compared. Data were statistically analyzed with analysis of variance test. RESULTS: Significant differences (P < .05) were found in the tested parameters between the 2 groups. The DNS group was significantly more precise, showing smaller mean values in the angulation (4.8°) and in the maximum distance from the ideal position (0.34 mm), when compared with MA group (mean values, 21.2° and 0.88 mm, respectively). CONCLUSIONS: Hence, we may conclude that the use of DNS increased the benefits of UCACs by minimizing the potential risk of iatrogenic weakening of critical portions of the crown and reducing negative influences to shaping procedures.


Asunto(s)
Preparación de la Cavidad Dental , Diente Molar , Tomografía Computarizada de Haz Cónico
11.
Sci Rep ; 10(1): 8127, 2020 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-32415190

RESUMEN

The present study aimed to evaluate the efficiency, effectiveness, and biocompatibility of two agents used for the chemomechanical removal of carious dentin. Sixty extracted carious human teeth were treated with a conventional bur (CBG) or chemomechanical agents - Papacarie Duo (PG) and Brix 3000 (BG). Treatment efficiency and effectiveness were assessed by the working time for carious dentin removal and Knoop microhardness values, respectively. Human pulp fibroblasts (FP6) were used to evaluate cytotoxicity by incorporating MTT dye, and genotoxicity was evaluated with the micronuclei test. The carious tissue was removed in a shorter time with CBG (median = 54.0 seconds) than the time required for chemomechanical agents (p = 0.0001). However, the time was shorter for Brix 3000 (BG) than that for Papacarie Duo (PG), showing mean values of 85.0 and 110.5 seconds, respectively. Regarding microhardness testing, all approaches tested were effective (p < 0.05). The final mean microhardness values were 48.54 ± 16.31 KHN, 43.23 ± 13.26 KHN, and 47.63 ± 22.40 KHN for PG, BG, and CBG, respectively. PG decreased cell viability compared to that of BG, but it presented no genotoxicity. Brix 3000 may be a good option for chemomechanical dentin caries removal due to its reduced removal time and lower cytotoxicity compared to the other treatment options.


Asunto(s)
Caries Dental/terapia , Preparación de la Cavidad Dental/métodos , Dentina/química , Fibroblastos/efectos de los fármacos , Dureza/efectos de los fármacos , Papaína/farmacología , Hipoclorito de Sodio/farmacología , Proliferación Celular , Células Cultivadas , Dentina/efectos de los fármacos , Fibroblastos/patología , Humanos , Técnicas In Vitro , Estrés Mecánico
12.
Dent Mater J ; 39(4): 624-632, 2020 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-32295986

RESUMEN

The study evaluated the quality of gingival margins created by cervical margin relocation (CMR) technique using different materials and assessed the consistency of the results obtained by two in vitro methods: microleakage test and scanning electron microscopy (SEM). Mesio-occlusal-distal cavities with subgingival proximal margins were prepared. Mesial margins were elevated supragingivally with total-etch adhesive and flowable composite (Group 1) or with universal adhesive and bulk-fill flowable composite (Group 2). Distal margins were not elevated. Teeth were restored with CAD/CAM overlays. Marginal quality was evaluated by microleakage test and SEM observation of epoxy resin replicas. Statistical analyses showed no significant correlations between microleakage scores and percentage of marginal integrity observed under SEM at CMR margins, lower microleakage scores at margins without CMR compared to CMR margins, lower microleakage scores in Group 2 than in Group 1 and no difference in SEM integrity between groups at CMR margins.


Asunto(s)
Filtración Dental , Restauración Dental Permanente , Resinas Compuestas , Diseño Asistido por Computadora , Preparación de la Cavidad Dental , Adaptación Marginal Dental , Cementos de Resina
13.
BMC Oral Health ; 20(1): 98, 2020 04 07.
Artículo en Inglés | MEDLINE | ID: mdl-32264864

RESUMEN

BACKGROUND: We aimed to investigate the load-induced strain variation in teeth with unrestored and resin-based composite restored non-carious cervical lesions (NCCLs). METHODS: Twelve extracted premolars were provided for measuring buccal-side root NCCLs. Strain gauges were fixed at four measuring sites of each tooth, two at the buccal surface and two at the lingual surface. NCCLs were prepared with occlusal margins at the cemento-enamel junction. A static 9-kg load was applied at seven occlusal loading points: buccal cusp tip (BC), inner inclination of the BC, lingual cusp tip (LC), inner inclination of the LC, center of the mesial marginal ridge or distal marginal ridge, and center of the central groove. The strain was detected at each site in teeth with NCCL depths of 0 (control), 0.5, 1.0, and 1.5 mm. Each NCCL was restored using an adhesive composite resin, and the strains were re-measured. RESULTS: The strains at the NCCL occlusal and gingival margins decreased with increasing defect depths, and the effect was significant when the depth of the defect was 1.5 mm. Loading on the buccal and lingual cusps induced prominent strain variation. The strains at all depth distribution recovered to nearly intact conditions when the NCCLs were restored. CONCLUSIONS: NCCLs at 1.5 mm depth are detrimental, but they can be restored using resin composites. CLINICAL SIGNIFICANCE: The existence of NCCLs should not be ignored. The depth of the NCCL may affect the progression of the lesion. Resin composite restoration is an appropriate method for preventing persistent NCCL deterioration.


Asunto(s)
Diente Premolar/patología , Resinas Compuestas , Esmalte Dental/fisiología , Restauración Dental Permanente , Abrasión de los Dientes/terapia , Cuello del Diente/patología , Erosión de los Dientes/terapia , Diente Premolar/fisiología , Fuerza Compresiva , Preparación de la Cavidad Dental , Materiales Dentales , Análisis del Estrés Dental , Humanos , Abrasión de los Dientes/fisiopatología , Erosión de los Dientes/fisiopatología
14.
J Dent ; 96: 103321, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32194201

RESUMEN

OBJECTIVE: To investigate current teaching and operative techniques for posterior composite resin restorations in dental schools in Austria, Germany, and Switzerland. METHODS: Data on teaching, including operative techniques applied in the placement of posterior composites, were collected by means of a 25-item validated questionnaire sent to the Heads of Department of Operative/Restorative Dentistry at all 38 dental schools in Austria, Germany, and Switzerland. Responses were compiled in Excel and analysed. RESULTS: Thirty-three schools responded to the survey, resulting in a response rate of 87 %. All dental schools indicated teaching of 2- and 3-surface posterior composite restorations. About one third only of the preclinical teaching is assigned to teaching posterior composite restorations, while the vast majority of posterior restorations placed by students in their clinical instruction are composite (89.6 ±â€¯9.3 %). Most dental schools teach few contraindications to posterior composites, except for adverse reactions such as allergies. All dental schools consider moisture control to be important, while approaches to the management of exposed dentine differ. CONCLUSIONS: The teaching of the placement of posterior composite restorations is common to all the dental schools in Austria, Germany, and Switzerland which participated in the present study. Most aspects of the teaching were found to be consistent amongst the schools. However, marked variations were observed in respect of operative techniques for the placement of posterior composites. CLINICAL SIGNIFICANCE: Graduates from dental schools in Austria, Germany, and Switzerland may be found to have received theoretical, preclinical, and clinical instruction in posterior composites, but do show some variation in approach to the management of exposed dentine.


Asunto(s)
Preparación de la Cavidad Dental , Restauración Dental Permanente , Austria , Resinas Compuestas , Curriculum , Operatoria Dental , Alemania , Humanos , Facultades de Odontología , Encuestas y Cuestionarios , Suiza , Enseñanza
15.
J Dent Educ ; 84(3): 367-376, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32176342

RESUMEN

The aim of this study was to evaluate the contribution of virtual reality to the conventional analogic training environment and show the complementarity of conventional techniques and virtual reality in the learning of dental students. All 88 first-year dental students at a dental school in France in early 2019 were randomly assigned to one of two groups: group 1 (n = 45) was assigned to cavity preparations on a haptic simulator (Virteasy) and group 2 (n = 43) was assigned to conventional practical work on plastic analogue teeth (Kavo). Following three training sessions, the students in group 1 took a final exam on the same plastic analogue teeth exercise. The results showed improvement in the drilling skill of both groups. The simulator-trained group (group 1) had similar results to the plastic analogue-trained group (group 2) in the final test on a plastic analogue tooth. In this study, virtual reality allowed an assessment based on objective criteria and reduced the subjectivity of evaluations conducted on plastic analogue teeth. Considering the saving of supervision and teaching time as well as the material gain offered by virtual reality, the learning methods of haptic simulators are educational options that should be considered by dental educators.


Asunto(s)
Preparación de la Cavidad Dental , Educación en Odontología , Entrenamiento Simulado , Competencia Clínica , Simulación por Computador , Francia , Humanos , Estudiantes de Odontología , Interfaz Usuario-Computador
16.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 55(3): 171-177, 2020 Mar 09.
Artículo en Chino | MEDLINE | ID: mdl-32193913

RESUMEN

Objective: To investigate the superficial and internal adaptations of a new self-curing composite resin in Class Ⅴ cavities. Methods: Class Ⅴ cavities were prepared in 56 caries-free human maxillary premolars (collected from Department of Oral and Maxillofacial Surgery, Capital Medical University School of Stomatology) extracted for orthodontic reasons, and these premolars were assigned into two groups (28 specimens each group). Experimental group were restored with a pretreating agent (Tooth primer) and a new self-curing composite resin (Bondfill SB). Control group were restored with a self-etching adhesive (Scotchbond Universal) and a light-curing composite resin (Z100). The restored teeth were subjected to a fatigue test to simulate temperature change and occlusal load in oral environment: mechanical cycles (1 200 000 cycles at 49 N with a frequency of 1 Hz) and thermocycles (3 000 cycles from 5 ℃ to 55 ℃ with a dwelling time of 1 min each). Before and after fatigue test, restored teeth were immersed in an 50% ammoniacal silver nitrate solution and reduced. Superficial perfect margin percentage value and length of silver deposit along the internal interface were quantified by scanning electron microscopy (SEM). Ultrastructure of dentin bonding interface was analyzed by transmission electron microscope (TEM). Results: Before fatigue test, superficial gaps at dentin side in the specimens in experimental group were narrower than those in control group, and length of silver deposit at enamel side [(0.67±0.15) µm] in specimens in the control group was significantly lower than that in the experimental group [(33.54± 10.27) µm] (P<0.05). After the fatigue test, control group showed higher perfect margin percentage value to enamel [(55.08±15.20)%] than experimental group [(25.15±12.47)%] did (P<0.05). After the fatigue test, cohesive failures could be more easily found in experimental group than in control group at surficial and internal interfaces. In TEM results, more silver deposits were found at dentin bonding interface in control group than in experimental group before the fatigue test. After the fatigue test, the deterioration at dentin bonding interface mostly happened at the bottom of the hybrid layer in control group, while in experimental group it could be found at the bottom of the hybrid layer and in the restorative material. Conclusions: When restored in Class Ⅴ cavity, the studied light-curing composite shows better superficial and internal adaptations for enamel than the new self-curing composite resin and the new self-curing composite resin shows good superficial and internal adaptations for dentin.


Asunto(s)
Resinas Compuestas , Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios , Compuestos de Boro , Preparación de la Cavidad Dental , Cementos Dentales , Restauración Dental Permanente , Dentina , Humanos , Técnicas In Vitro , Ensayo de Materiales , Metacrilatos , Metilmetacrilatos , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Cementos de Resina , Dióxido de Silicio , Circonio
17.
Eur J Oral Sci ; 128(1): 89-99, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-32032451

RESUMEN

In this study, polyurethane dimethacrylate (PUDMA) was synthetized from different components and incorporated into a direct resin composite restoration system with the aim to buffer tooth-resin interfacial stresses and maintain the marginal adaptation. The tensile strength, elongation at fracture (ε), and thermal stability of the PUDMA layer were characterized, showing a tensile strength of 22 MPa, an ε of 112%, and a thermal decomposition temperature of about 282°C. In addition, the degree of conversion, water sorption/solubility, hydrophobicity, microtensile bond strength (µTBS), marginal leakage, and cytotoxicity in vitro were evaluated for the PUDMA layer. The data were analyzed using one-way ANOVA, except for leakage depths (which were analyzed using the Wilcoxon paired-rank test). The level of significance was set at 0.05. Compared with dental adhesives, PUDMA displayed a higher degree of conversion, lower water sorption/solubility, and improved hydrophobicity and biocompatibility in vitro. After thermocycling, the µTBS of the restoration system containing PUDMA had increased compared with the µTBS at 24 h. Restorations containing PUDMA showed lower leakage depths than those which did not contain PUDMA. In conclusion, because of its hydrophobic and elastic nature, the PUDMA layer, when used as an intermediate between tooth and resin restoratives, may buffer interfacial stresses, improve the stability and durability of the bonding interface, and reduce microleakage.


Asunto(s)
Metacrilatos , Poliuretanos , Bisfenol A Glicidil Metacrilato , Resinas Compuestas , Recubrimiento Dental Adhesivo , Preparación de la Cavidad Dental , Filtración Dental , Recubrimientos Dentinarios , Humanos , Ensayo de Materiales , Cementos de Resina , Resistencia a la Tracción
18.
Clin Oral Investig ; 24(10): 3529-3538, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32025883

RESUMEN

OBJECTIVES: The aim of this randomized, controlled, three-arm parallel-group, double-blinded clinical trial was to investigate the clinical and microbiological effects of the ozone application in stepwise excavation of primary molars. MATERIALS AND METHODS: This study was conducted in in vivo conditions with 105 lower primary molars that had deep caries lesions. The teeth were randomly divided into three groups: (I) control group, conventional stepwise excavation with no disinfectants; (II) CHX (positive control) group, 2% chlorhexidine digluconate; and (III) experimental group, ozone application. Dentine samples were collected at 4 different time points (T0, at the first appointment, after partial removal of carious dentin; T1, at the first appointment, after applying disinfection procedure; T2, at the second appointment - at the end of the 4-month period - immediately after the removal of the temporary restoration; T3, at the second appointment, after the final excavation) for the microbiological analysis of mutans streptococci and lactobacilli and the total number of colony-forming units. Clinical changes including dentin color, humidity, and consistency were recorded. Data were analyzed using the Mann-Whitney U test, Friedman test, and chi-squared test (p = 0.05). RESULTS: The dentin became harder and drier after 4 months in all the groups. There was a gradual reduction in the total number of microorganisms in all the three groups. Bacterial reduction was greater in the CHX group compared to the ozone group (p = 0.002) and was greater in the ozone group compared to the control group (p = 0.015) after 4 months (control, 78%; CHX, 93%; ozone, 82%). CONCLUSION: Stepwise excavation of primary teeth provided successful outcomes in all the groups. Moreover, CHX, due to its practicality and cost-effectiveness, can be effectively used with one- or two-step indirect pulp therapies. CLINICAL RELEVANCE: Usage of cavity disinfectants in the stepwise excavation procedure contributes to the reduction of bacterial population in the cavity, which may allow the avoidance of the second step of the indirect pulp therapy for primary teeth.


Asunto(s)
Caries Dental , Diente Molar , Preparación de la Cavidad Dental , Dentina , Humanos , Ozono , Diente Primario
19.
J Endod ; 46(4): 539-544, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32067720

RESUMEN

INTRODUCTION: The aim of this study was to investigate the influence of apical filling material and the modification made to the apical preparation design in surgical endodontics on the areas of stress concentration in the mesial root of a mandibular molar using finite element analysis. METHODS: The filling material was injected under 2 conditions (ie, with or without mineral trioxide aggregate retrograde filling). The apical preparation design was modified by extending the preparation mesially while maintaining a similar prepared area. We contained the displacement of all the nodes at the base of the supporting bone and applied a force of 150 N to the vertical axis. We analyzed stress generation and concentrations numerically for all cavity design groups. RESULTS: In the presence of retrograde filling, the von Mises stress decreased gradually according to the enlargement of the prepared cavity in the subgroups. When the retrograde filling was absent, the von Mises stress increased as the prepared cavity enlarged. The modification of the apical preparation extending in the mesial direction showed a drastic decrease in stress concentration. CONCLUSIONS: Within the limitations of this study, it was advantageous to perform mesial retrograde preparation within the mesial root dentin to maintain a balanced root dentin on both sides of the apical preparation and create a low-stress field. The surgeon should be careful not to wash out or dislodge the retrograde filling material during obturation to avoid failure of surgery.


Asunto(s)
Endodoncia , Diente Molar , Preparación de la Cavidad Dental , Análisis de Elementos Finitos , Raíz del Diente
20.
Eur J Dent Educ ; 24(3): 425-432, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32080964

RESUMEN

OBJECTIVE: The objective of this study was to evaluate the effects of magnification on the quality of two pre-clinical procedures, class I cavity preparations and composite resin restorations, and to evaluate the working posture. METHODS: This was an experimental laboratory study. The response variables were the quality of cavity preparations and Class I restorations as well as the working posture adopted during the execution of these procedures. The independent variables were the magnification system under four levels (unaided visualisation, the use of a simple loupe, the use of a Galilean loupe and the use of a Keplerian loupe) and the artificial teeth treated. Class I cavity preparations and restorations (N = 320) were performed using standardised procedures, and the quality achieved was evaluated using pre-established criteria. Working posture was recorded using digital video cameras and was evaluated using the Compliance Assessment of Dental Ergonomic Posture Requirements (CADEP). A two-factor analysis of variance (ANOVA) and multiple comparison test were performed (α = 0.05). RESULTS: The quality of cavity preparation did not differ significantly amongst the different magnification systems (P = 0.082). Galilean and Keplerian systems had a positive impact on restoration quality only for the left mandibular first molar (P = 0.04). Higher posture scores were observed when Galilean and Keplerian loupes (P = 0.01) were used, regardless of the tooth being treated. CONCLUSION: The use of Galilean and Keplerian magnification lenses did not affect the quality of the pre-clinical procedures performed whilst improved the scores of ergonomic posture.


Asunto(s)
Educación en Odontología , Lentes , Atención Odontológica , Preparación de la Cavidad Dental , Restauración Dental Permanente , Ergonomía , Humanos , Postura
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