Restoring anterior and posterior aesthetics and function.
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Aged↗
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Results for “DENTAL RESTORATION, PERMANENT”
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Microleakage of cervical cavities restored with flowable composites.
PURPOSE: To investigate the microleakage of cervical cavities restored with flowable composites in conjunction with an all-in-one adhesive system (AQ Bond) and an experimental two-step self-etching primer system (ABF) after thermocycling or flexural load cycling. METHODS: 180 wedge-shaped cervical cavities on the labial surfaces of bovine incisors were treated with AQ Bond or ABF according to the manufacturers' instructions. The treated cavities were filled with one of three flowable composites (AElite Flo, Metafil Flo or Protect Liner F). Ten of 30 specimens for each group were immersed in 0.5% basic fuchsin solution immediately after finishing of the restorations. Specimens to be subjected to thermocycling (5-60 degrees C, 15 seconds dwell time, 5000 cycles) or to flexural load cycling (approximately 0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 Hz) prior to immersion in the dye were also prepared. After 24-hour storage in the dye solution, the teeth were sectioned longitudinally through the center of the restorations, and the degrees of dye penetration scored. The microleakage scores of a hybrid composite (Clearfil AP-X) obtained from our previous study were used for comparison. The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test (P < 0.05). RESULTS: No significant differences in the microleakage patterns and scores were found among the flowable composites. On the other hand, significant differences in the microleakage patterns and scores were observed between the flowable and the hybrid composites. Thermocycling caused deterioration of marginal integrity, and the flowable composites showed more microleakage than the hybrid composite. In contrast, flexural load cycling did not cause deterioration of the marginal integrity when the cavities were filled with the flowable composites. Statistical analysis also revealed that the adhesive systems played a large role in the microleakage patterns.
Animals↗
Dental fracture fragment attachment: fracture model and luting agent comparisons.
PURPOSE: The purpose of this study was twofold: 1. To compare two different research models for simulating a traumatic anterior tooth fracture: the blunt trauma method (standard method) and an AL2O3 sectioning method (experimental method). 2. To compare the bond strength of tooth fragments bonded with resin modified glass ionomer vs. a light cured composite resin. METHODS: Two hundred bovine incisors were used in the study and kept in plain tap water throughout. The study consisted of five basic steps: 1. Fracture of the teeth by either blunt trauma (chisel and hammer) or AL2O3 sectioning disc. 2. Luting of the fractured fragments back to the teeth using either a composite resin or resin modified glass ionomer. 3. Thermocycling of the repaired teeth. 4. Dislodging the teeth to determine the strength of repair. 5. Determination of fracture type. RESULTS: One-way ANOVA revealed a statistically significant difference in the forces required to fracture the resin modified glass ionomer and composite resin regardless of whether the teeth were originally fractured with the blunt force method (p=0.030) or the disc sectioning method (p=.001). One-way ANOVA also revealed a statistically significant difference between the forces required for fracture by blunt trauma and the disc fracture techniques with the resin modified glass ionomer group (p=0.000345). However, there was no significant difference when the two techniques were compared for the composite resin (p= 0.2941). CONCLUSIONS: 1. The resin modified glass ionomer was significantly stronger than the composite resin when both the blunt trauma and the disc fracture techniques were employed. 2. The study's results do not support substituting the ease of the AL2O3 disc for the more time-consuming blunt trauma method.
Analysis of Variance↗
Effects of cavity configuration on composite restoration.
This study evaluated the effects of various cavity configurations on the bond strength, microleakage, flexural strength and elastic modulus of a hybrid (Clearfil AP-X) and a microhybrid (Esthet-X) composite restorative. After the specimens were made with C-factors of less than 1, 2.4 and 3.4, flexural strength and elastic modulus were evaluated in three-point bending using a mechanical testing machine. Fragments of the fractured specimens were selected randomly and the fracture surfaces were examined in SEM. To evaluate the microtensile bond strength and microleakage of composite restorations in bovine cavities, C-factors (ratio of bonded to non-bonded cavity surface) were controlled as 1.0, 2.3, 3.0 and 3.7. All specimens were stored in distilled water at 37 degrees C for 24 hours and tested in a universal testing machine (EZ Test, Shimadzu, Japan). For the microleakage test, teeth with restorations were stained with silver nitrate and examined by two examiners under a stereomicroscope at 40x magnification. The hybrid composite showed higher mechanical properties than the microhybrid composite. The flexural strength and elastic modulus of both composites decreased when polymerized under greater constraint, that is, with increasing C-factor. Mean microtensile bond strength to dentin was also decreased with increasing C-factor for both types of composites. Microleakage scores for the hybrid composite restorations were generally higher than the microhybrid composite.
Analysis of Variance↗
Salvaging a compromised tooth using a combination amalgam core/composite window technique.
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Aged↗
Techniques for altering perception of tooth size.
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Adult↗
Reattachment of a fractured maxillary tooth: a case report.
A 14-year-old male patient reported with a horizontal fracture of almost the entire crown of a maxillary incisor, extending subgingivally at the palatal side. After root canal therapy and electrosurgery, the tooth fragment was reattached using a total-etch dentin-bonding system and a hybrid composite. Due to enamel cracks and the necessity for more retention, the labial surfaces of the teeth were veneered with a micro-filled composite. The clinical situation of the reattached teeth was confirmed successful by radiographic and photographic assessment after 1, 3, 6, and 12 months. The restoration of an anterior tooth with original tooth fragment in young patients has advantages over conventional composite or prosthetic restorations. However, reattached teeth with fracture extending subgingivally, require long-term follow-up.
Adolescent↗
[Effects of post material on stress distribution in dentine].
OBJECTIVE: To investigate stress distribution of different material restored post-cores in dentine and provide a theoretical guidance for clinical use. METHODS: A three-dimensional finite element model of maxillary central incisor restored with post-core and PFM crown was constructed by SCT scan technology. Based on this model, stress distribution in dentine was analyzed before and after post-core restorations with 6 different materials, including cast Ni-Cr alloy, cast titanium alloy, cast gold alloy, glass fiber reinforced composite, polythene fiber reinforced composite, and common composite resin. RESULTS: When the tooth was restored with cast Ni-Cr alloy post and PFM crown, the maximum tensile stress and Von Mises stress in dentin at post apex increased 152% and 162% respectively, compared with a tooth restored only with PFM crown. If polythene fiber reinforced composite was used as post material, the stress distribution did not significantly change. When the other materials were used for the post, the stress distribution changed greatly. The elastic modulus of post-core materials affected the stress distribution pattern in dentine. CONCLUSION: The materials with elastic modulus similar to that of dentin, such as polythene fiber reinforced composite, may be suitable for post restoration.
Chromium Alloys↗
Effects of aging on mechanical properties of composite restoratives: a depth-sensing microindentation approach.
This study investigated the effects of aging on the hardness and modulus of two composites (Tetric Ceram [TC], Vivadent; Esthet X [EX], Dentsply), a conventional (Compoglass [CG], Vivadent) and a posterior compomer (Dyract Posterior [DP], Dentsply) using a depth-sensing microindentation approach. Seven specimens (3-mm wide x 3-mm long x 2-mm deep) of each material were made and conditioned in distilled water at 37 degrees C. Hardness and modulus of the materials were determined at seven and 30 days using depth-sensing microindentation testing with the Instron MicroTester. Hardness was determined by dividing the peak load over the maximum projected contact area while effective modulus was calculated by analysis of the loading/unloading P-h curves and the analytical model according to Oliver and Pharr (1992). Results were analyzed using one-way ANOVA/Scheffe's post-hoc test and Independent Samples t-test at significance level 0.05. Mean Vickers Hardness (HV) ranged from 46.60 to 58.67 and 44.44 to 59.41 at seven and 30 days, respectively. Mean indentation modulus ranged from 9.57 to 9.95 and 9.19 to 10.03 for the same time periods. At both time periods, EX was significantly harder than all the other materials and HV values for TC were significantly greater than CG. No significant difference in hardness and modulus was observed between seven and 30 days for all materials with the exception of CG. For the latter, a significant decrease in mechanical properties was detected over time.
Analysis of Variance↗
Effect of thermal and mechanical load cycling on nanoleakage of Class II restorations.
PURPOSE: To evaluate the effect of thermal and mechanical cycling on the degree and pattern of nanoleakage on cervical margins of Class II restorations. MATERIALS AND METHODS: Forty box-type Class II cavities were prepared on bovine incisors. The cavities were restored with Single Bond and Z-250 composite resin (3M-ESPE) according to manufacturer's instructions. The teeth were randomly assigned to 4 groups: G1, control; G2, thermal cycling (2000 cycles, 5 to 55 degrees C); G3, mechanical load cycling (100,000 cycles, 50 N); G4, thermal and mechanical load cycling group (2000 cycles 5 to 5 degrees C/100,000 cycles, 50 N). The specimens were then sealed leaving a 1 mm window around the cervical margin interface. Samples were immersed in a 50% w/v ammoniacal silver nitrate solution for 24 h, and exposed to a photodeveloping solution for 8 h. Specimens were sectioned longitudinally, embedded in epoxy resin, polished and mounted on stubs, gold sputter coated, and examined under SEM using backscattered electron mode. Silver particle penetration length was measured directly on the SEM monitor and calculated as the percentage of the total length of cut dentin surface that was penetrated by silver nitrate. The data were analyzed with ANOVA and Fisher's PLSD test (p < 0.05). RESULTS: The degree of nanoleakage significantly increased when thermal and mechanical cycling was performed on the same specimens, as compared to the other groups (p < 0.05). No differences were observed between the control, thermal cycling, and mechanical cycling groups. No difference in nanoleakage pattern was observed between the groups. CONCLUSION: Thermal and mechanical cycling combined adversely affected nanoleakage values. Simulation of the oral condition might be crucial to better evaluate and understand the performance of adhesive materials.
Analysis of Variance↗
Marginal gap repair with flowable resin-based composites.
This study was designed to test the hypothesis that the flowable/dentin interface has the weakest bond and highest frequency of failure when a resin-based composite is repaired using a flowable composite. Comparing three specific groups--dentin, flowable composite, and hybrid composite-under the Kruskal-Wallis test showed that the mean bond strength values at the flowable/dentin interface and within the dentin were significantly lower than those at the hybrid/flowable interface and within the flowable resin. Dentin near the pulp chamber yielded consistently lower bond strength values than dentin located at the dentino-enamel junction. Bonding at the flowable resin/dentin interface showed the weakest bond and highest frequency of failure.
Analysis of Variance↗
[Comparison of fracture resistance of pulpless teeth restored with fiber reinforced composite posts and three kinds of resin core material].
OBJECTIVE: To compare the fracture resistances of pulpless teeth restored with FRC (Fiber Reinforced Composite) posts and three kinds of resin core material. METHODS: A total of 42 recently extracted upper incisors were randomly divided into 3 groups. Group A was restored with prefabricated glass-fiber posts and Artglass polymer core; group B with prefabricated glass-fiber posts and Charisma composite resin core; and group C with prefabricated glass-fiber posts and AB composite resin core. In every group, the core material was processed by hot-press and non hot-press respectively. The posts size and shape were identical in the 3 groups. All teeth were fully covered with polycarbonate resin crowns. Fracture resistance was measured by applying point force at 130 degrees to the long axis of the teeth on an universal testing machine. RESULTS: Mean fracture threshold was 505.4 N +/- 42.0 N and 564.1 N +/- 41.7 N in group A, 411.3 N +/- 23.3 N and 315.3 N +/- 19.1 N in group B and 358.4 N +/- 36.1 N and 423.4 N +/- 47.5 N in group C. In all groups, there was no posts fracture and polycarbonate resin crowns fragmentation. CONCLUSION: The composite restoration of FRC posts combined with resin core and resin crown can improve the fracture resistance of the pulpless roots. The strength of resin core material can be increased by hot-press methods.
Composite Resins↗
Long-term bond strength of restorations subjected to thermo-mechanical stresses over time.
PURPOSE: To evaluate the long-term effect of thermal and mechanical cycling on dentin bond strength to cervical margins of Class II restorations. METHODS: Sixty Class II slot cavities were prepared in bovine incisors. The cavities were restored with Single Bond and Z-250 composite according to manufacturer's instructions. The teeth were then divided into two groups (n = 30): specimens that would receive thermo-mechanical load cycling (2,000 cycles 5-55 degrees C/100,000 cycles of 50 N loading) (TM) and the control (C). Fifteen specimens from each group were tested at baseline and the remaining 30 specimens were stored in distilled and deionized water at 37 degrees C and tested after 1 year. For microtensile evaluation, the restorations were sectioned perpendicular to the cervical bonded interface into 0.7 +/- 0.2 mm thick slabs. The slabs were further trimmed at the interface to 1.4 < or = 0.2 mm with a fine diamond bur to produce a cross-sectional surface area of ca. 1 mm2. Specimens were then subjected to microtensile bond testing. The bond strength data were analyzed using two-way ANOVA and Fisher's PLSD test (P < 0.05). Fracture mode analysis was performed using SEM. RESULTS: At baseline, bond strength of the TM group was significantly lower when compared to the C group (P = 0.012). However, after 1 year storage, a significant decrease in bond strength was observed for the C group compared to baseline. No significant differences were noted between the C and TM groups at 1 year. No interaction was observed between groups (C and TM) and storage time (P = 0.098). For the fracture mode evaluation, at baseline, mixed failure was predominant for the C group, and increased after TM. Decreased mixed failure was observed after 1-year storage, with a concomitant increase in interphase failure.
Animals↗
Crown lengthening: basic principles, indications, techniques and clinical case reports.
Sometimes, in order to properly restore teeth, surgical intervention in the form of a crown-lengthening procedure is required. Crown lengthening is a periodontal resective procedure, aimed at removing supporting periodontal structures to gain sound tooth structure above the alveolar crest level. Periodontal health is of paramount importance for all teeth, both sound and restored. For the restorative dentist to utilize crown lengthening, it is important to understand the concept of biologic width, indications, techniques and other principles. This article reviews these basic concepts of clinical crown lengthening and presents four clinical cases utilizing crown lengthening as an integral part of treatments, to restore teeth and their surrounding tissues to health.
Alveolar Process↗
The repair methods for fractured metal-porcelain restorations: a review of the literature.
Metal-ceramic restorations are popular in restorative dentistry. Although metal-ceramic restorations are universally accepted, they have such disadvantages as occasional fractures of the veneer. Fracture and loss of the veneering ceramic of a fixed partial denture is troublesome. If the restoration is in an otherwise acceptable condition, dentists frequently use different repair methods to avoid removal of the restoration. The techniques for repair of fractured porcelain restorations include a) rebonding the fractured chip to the fixed restoration, b) fabricating a porcelain veneer to bond to the fractured porcelain, and c) using a composite resin to restore the fractured porcelain. This article presents a literature review of the intra and extra oral repair techniques for fractured metal-porcelain restorations. A PubMed data base search was conducted for the repair of porcelain.
Composite Resins↗
Esthetic restoration of discolored primary incisors.
Restoring primary teeth can be a strenuous task for many dentists who would like to have an esthetic, easy-to-use and relatively quick restoration for children. But, the restoration of carious, fractured or discolored primary incisors gives the dentist the satisfaction of knowing that he/she has restored the smile and self-confidence of a growing child. This article describes a technique which is relatively easy and produces a beautiful outcome in a relatively short time. The author has used the technique in hundreds of children for over twenty-five years. Modifications in the technique have been made as newer materials and techniques have evolved.
Acid Etching, Dental↗
Polymerization shrinkage of flowable resin-based restorative materials.
This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultraseal XT and Wave). Measurements for linear polymerization displacement and polymerization forces were performed using custom made measuring devices. Polymerization of the test materials was carried out for 60 seconds by means of a light curing unit, and each property was measured for 180 seconds from the start of curing in eight specimens for each material. Statistical evaluation of the data was performed with one-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) test (p=0.05) and simple linear regression. A wide range of values was recorded for linear polymerization displacement (26.61 to 80.74 microns) and polymerization forces (3.23 to 7.48 kilograms). Statistically significant differences among materials were found for both properties studied. Very few materials (Freedom, Glacier, and Photo SC) presented low values of linear polymerization displacement and polymerization forces (similar to hybrid resin composites), while the majority of materials presented very high values in both properties studied. Study of the shrinkage kinetics revealed the exponential growth process of both properties. The polymerization forces development exhibited a few seconds delay over linear polymerization displacement. Simple linear regression showed that the two polymerization shrinkage properties that were studied were not highly correlated (r2=0.59).
Analysis of Variance↗
Influence of dietary solvents on strength of nanofill and ormocer composites.
The objective of this study was to determine the influence of dietary solvents on the shear punch strength of nanofill (Filtek Supreme [FS], 3M-ESPE) and ormocer (Admira [AM], Voco) composites. The strength of these materials was also compared to a minifill composite (Z250 [ZT], 3M-ESPE), a compomer (F2000 [FT], 3M-ESPE) and a highly viscous glass ionomer cement (Ketac Molar Quick [KM], 3M-ESPE). Thirty-two specimens (8.7 mm diameter and 1-mm thick) of each material were made, randomly divided into four groups of eight and conditioned for one week as follows-Group 1 (control): distilled water at 37 degrees C; Group 2: 0.02M citric acid at 37 degrees C; Group 3: 50% ethanol-water solution at 37 degrees C and Group 4: heptane at 37 degrees C. After conditioning, the specimens were restrained with a torque of 2.5 Nm and subjected to shear punch strength testing using a 2-mm diameter punch at a crosshead speed of 0.5 mm/minute. The shear punch strength of the specimens was computed and data subjected to ANOVA/Scheffe's tests at significance level 0.05. With the exception of AM, the strength of all materials was not significantly influenced by dietary solvents. For AM, conditioning in heptane resulted in significantly higher shear strength values. The strength of the nanofill and ormocer composites was lower than the minifill composite but higher than the compomer and highly viscous glass ionomer cement investigated.
Analysis of Variance↗