Effects of pre-heating on physical-mechanical-chemical properties of contemporary resin composites.

This research assessed the effects of pre-heating on the physical-mechanical-chemical properties of different resin composites. For this, resin composites were evaluated in 6 levels: Admira/ADM, Vitra/VIT, Filtek Supreme/FS, Filtek Supreme Flowable/FSF, Filtek One/FO, and Filtek Bulk Fill Flowable/FBF; temperature was evaluated in 4 levels using a composite heater: room temperature/22 ºC, 37 ºC, 54 ºC, and 68 ºC. Response variables were: degree of conversion/DC, flexural strength/FS and color stability/ΔE (immediately after light curing/LC, after 7 days of dark-dry-storage, and after 24 h and 3 days of artificial aging in water at 60 ºC). Data were subjected to 2-way ANOVA (DC and FR) and 3-way repeated measurements ANOVA (ΔE), all followed by Tukey's test (α = 5%). DC were similar (FBF, FS, and FSF) or increased (ADM, FO, and VIT) as the temperature increased. Results of FR were unchanged or increased for all composites except VIT and ADM. High-viscosity composites (VIT and FS) showed higher FR values than low-viscosity composite (FSF). For bulk-fill composites, FBF and FO showed similar results, but lower than high-viscosity composites. Results of color stability showed acceptable values up to 3 days aging except for ADM and FSF. ΔE was not influenced by pre-heating and, overall, ΔE: FS < VIT < FO < FSF < ADM < FBF. Only VIT and FS showed ΔE ≤ 3.3 (clinical threshold). Therefore, the effects of pre-heating depend on the material. The tested materials generally showed similar or enhanced properties after pre-heating (except ADM and VIT).

Clinical guidelines for posterior semidirect composite resin restorations: a case report with a 17-month follow-up.

Patients are always looking for conservative, esthetic, and long-lasting dental restorations, and the technique used directly influences the longevity of the treatment. The location of the restoration in the mouth and the extent of the decay influence the treatment choice. The larger the dimensions of the cavity preparation, the greater the difficulties in restoring the tooth using direct techniques. The semidirect technique, when indicated, can achieve satisfactory results. It is a relatively easy procedure, consisting of tooth preparation to receive an indirect restoration, fabrication of an alginate impression, fabrication of the composite resin restoration on a flexible cast, cementation, removal of excess cement, and occlusal adjustment. The aim of this case report is to present a viable alternative to direct and indirect restorations for posterior teeth with extensive decay. The article describes the extraoral semidirect technique for fabricating a composite resin restoration, highlighting its indications and discussing advantages and disadvantages.

The stamp technique for direct restoration in a ICDAS 4 carious lesion: A 4-year follow-up.

OBJECTIVE: This case report described the use of a stamping technique associated with a bulk fill composite to restore an ICDAS 4 carious lesion on a posterior tooth. The 4-year follow-up is also presented. CLINICAL CONSIDERATIONS: A 32-year-old patient presented a carious lesion on tooth 36 with an underlying dark shadow at the dentin seen from the noncavitated enamel occlusal surface, which was compatible with an ICDAS 4 carious lesion. The lesion was radiographically detected and the caries disease was treated with dietary and hygiene habits orientations. Before accessing the lesion and selectively removing the carious tissue, an occlusal stamp was made by applying a flowable resin composite to copy the anatomy of the noncavitated enamel surface. The cavity was restored using a bulk fill resin composite (Opus Bulk Fill, FGM) with 4-mm-thick increments. Before curing the last increment, a Teflon band was adapted at the uncured bulk fill composite surface and the occlusal stamp made with the flowable composite was pressed against it to reproduce the natural characteristics and initial occlusal anatomy. The top surface was light-activated for 40 s. After 4 years, small wear could be seen in the restoration, but still within clinically acceptable levels. CONCLUSION: The occlusal stamp technique allows reproduction of the natural anatomy of teeth affected by ICDAS 4 carious lesions with good clinical longevity over 4 years. CLINICAL SIGNIFICANCE: This case report presents the use of the stamp technique to restore a tooth affected by an ICDAS 4 lesion, in which a carious process reached the dentin and the enamel anatomy was still preserved. The bulk fill resin composite associated with the occlusal stamp was chosen to quickly restore the cavity with clinical predictability. Bulk fill composites allow the insertion of up to 4-mm-thick increments and offer lower shrinkage stress, good clinical longevity and a less time-consuming procedure in cases of posterior teeth, especially if associated with the stamp technique.

Direct vs indirect restorations for diastema closure: determining the suitable approach.

Determining the appropriate technique for diastema closure is challenging, and the decision must be evidence based. The objective of these case reports is to describe different approaches to diastema closure using direct and indirect techniques, focusing on the characteristics of the patient and clinical requirements to guide treatment. In the first case, a 16-year-old patient had multiple diastemas in the maxillary anterior dentition. The clinical evaluation revealed microdontia of the lateral incisors and malpositioned teeth. The treatment included tooth whitening and placement of composite resin veneers using a direct technique. In the second case, a 54-year-old patient displayed a disharmonious and esthetically compromised smile due to small teeth, color changes, multiple diastemas, incisal wear, and severe dentogingival disproportion. Based on the patient's expectations, the patient's age, and the presence of a "black triangle" interdental space, a multidisciplinary restorative treatment was proposed, including gingivoplasty, tooth whitening, and placement of ceramic laminate veneers using an indirect technique. Both approaches achieved successful esthetic rehabilitation and diastema closure with minimal intervention. The choice of procedure and restorative material, as well as the need for tooth preparation, varied based on the clinical requirements, patient expectations, and financial constraints. Careful treatment planning avoided lengthy and inefficient procedures.

Clinical perceptions of zirconia-reinforced lithium silicate ceramic: a case report and 6-month follow-up.

Zirconia-reinforced lithium silicate (ZLS) has recently been introduced in an effort to improve the mechanical properties of glass-ceramic materials. In vitro evaluations suggest that this class of material has high flexural strength and exhibits satisfactory adhesion to resin cement and wear resistance. Since few clinical reports of this novel material are currently available, the aim of this case report is to describe clinical perceptions regarding the handling and performance of ZLS ceramics when used for laminate veneers on the maxillary incisors.

Incorporation of TiO2 nanotubes in a polycrystalline zirconia: Synthesis of nanotubes, surface characterization, and bond strength.

STATEMENT OF PROBLEM: Despite numerous advantages such as high strength, the bond of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) to tooth structure requires improvement. PURPOSE: The purpose of this in vitro study was to evaluate the incorporation of TiO2 nanotubes into zirconia surfaces and the bond strength of resin cement to the modified ceramic. MATERIAL AND METHODS: TiO2 nanotubes were produced by alkaline synthesis, mixed with isopropyl alcohol (50 wt%) and applied on presintered zirconia disks. The ceramics were sintered, and the surfaces were characterized by confocal laser microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analysis. For bond strength, the following 6 groups (n=16) were evaluated: without TiO2 and Single Bond Universal; with TiO2 nanotubes and Single Bond Universal; without TiO2 nanotubes and Z-prime; with TiO2 nanotubes and Z-prime; without TiO2 and Signum Zirconia Bond; with TiO2 and Signum Zirconia Bond. After sintering, resin cement cylinders, diameter of 1.40 mm and 1 mm in height, were prepared and polymerized for 20 seconds. Specimens were stored in water at 37°C for 30 days and submitted to a shear test. Data were analyzed by 2-way ANOVA and Tukey honest significant difference (α=.05) tests. RESULTS: EDS analysis confirmed that nanoagglomerates were composed of TiO2. The shear bond strength showed statistically significant differences among bonding agents (P<.001). No significant differences were found with the application of nanotubes, regardless of the group analyzed (P=.682). The interaction among the bonding agent factors and addition of nanotubes was significant (P=.025). CONCLUSIONS: Nanotubes can be incorporated into zirconia surfaces. However, this incorporation did not improve bond strength.

Interdental papilla formation after diastema closure.

Due to improvements in esthetic dentistry, the number of patients seeking to obtain a more harmonious smile has increased. A 40-year-old woman was referred for treatment because she was dissatisfied with the effect that diastemas and a conoid tooth had on her smile. Her maxillary anterior teeth were relatively short, resulting in a compromised esthetic relationship between height and width. Orthodontic treatment for better distribution of her teeth was recommended to the patient, but she refused, wanting faster and less expensive treatment. After diagnostic and waxed-up study casts were obtained, composite resin esthetic mock-ups were made to confirm that sufficient space was left for formation of the interdental papilla. After the patient approved the mock-ups, her anterior teeth were submitted to bleaching, definitive restoration, and additional occlusal adjustments. At the 1-year follow-up, the patient exhibited a harmonious, esthetic smile without black spaces or periodontal inflammation.

Influence of Metal and Ceramic Abutments on the Stress Distribution Around Narrow Implants: A Photoelastic Stress Analysis.

PURPOSE: This study aimed to compare, through photoelastic analysis, the distribution of stresses around narrow implants with external hexagon (EH) and Morse taper (MT) connections, when single crowns made with metal and ceramic abutments were used. MATERIALS AND METHODS: Six photoelastic models were prepared, simulating the use of narrow EH and MT implants replacing a lateral incisor. These 2 groups received 3 different abutments: prefabricated metal abutments, customized metal abutments, and customized zirconia abutments. All crowns were identical and made with a leucite reinforced glass-ceramic. Vertical loads of 0 to 100 N were applied on the palatal surface of the crowns, and the photoelastic stress fringes developed in each model were captured in a high-definition video, and digital photographs were taken at 100 N. RESULTS: The abutment type and material influenced the stress distribution patterns around narrow implants with EH and MT connections. Stresses were generated mainly around the apical and lingual regions of the implants. CONCLUSIONS: For both connections, the prefabricated metal abutments presented better stress distribution around the implants when compared to customized metal and zirconia abutments because low stress levels were developed in smaller areas around the implants.

Minimum intervention in restorative dentistry with V-shaped facial and palatal ceramic veneers: A clinical report.

The esthetic and functional rehabilitation of worn anterior teeth should follow the principles of minimally invasive dentistry. When dental wear occurs at both the facial and palatal surfaces, the sandwich approach of reconstructing eroded anterior teeth with palatal followed by facial veneers is a straightforward treatment that preserves sound dental structure.

Fracture strength of the remaining dental structure after different cavity preparation designs.

The aim of this in vitro study was to evaluate the loss of tooth structure after cavity preparation for direct (retentive) and indirect (nonretentive) restorations and its relationship to the fracture strength of the prepared tooth. Sound human third molars (60 maxillary and 60 mandibular) were randomly assigned into 12 groups (n = 10) according to the type of cavity preparation and the respective buccolingual width. Class II mesio-occlusodistal cavity preparations, for both indirect inlay and direct resin restorations, were prepared with standardized dimensions of one-half, one-third, or one-quarter of the occlusal intercuspal distance. Fracture resistance was lower and weight loss was greater for all nonretentive preparations. Greater losses in weight and fracture resistance occurred when the buccolingual width for both types of cavities increased, except for the weight loss of the one-quarter and one-third indirect cavity preparations in the mandibular molars, and the fracture resistance of the one-half and one-third direct cavity preparations in maxillary molars. Higher tooth structure loss and lower fracture strength were recorded after preparation of the inlay cavities.

Planning extensive esthetic restorations for anterior teeth: use of waxed-up study casts and composite resin mock-ups.

The aim of this case report is to highlight the importance of appropriate planning protocols when direct composite resin restorations are used to solve extensive esthetic problems. A 30-year-old patient complained about her small maxillary anterior teeth and short upper lip. All teeth were healthy and light colored, and the patient exhibited good oral hygiene. The anterior teeth were relatively short, resulting in a compromised esthetic relationship between height and width. The maxillary and mandibular right central incisors were in an edge-to-edge relationship. After diagnostic casts and waxed-up study casts were obtained, occlusal adjustment and recontouring of the incisal and labial surfaces of the mandibular right central incisor were performed to increase overjet. To increase the volume of the upper lip, composite resin restorations were planned for the maxillary anterior teeth. To confirm that the contours and color of the new smile were acceptable to the patient, composite resin esthetic mock-ups were made directly in the mouth before the definitive procedure. After definitive restoration of the anterior teeth, additional occlusal adjustments were performed. At the 36-month follow-up, no fracturing or severe wear of the restorations was observed. The restored anterior guidance provided excellent function after 3 years of clinical service.

Post-cementation colorimetric evaluation of the interaction between the thickness of ceramic veneers and the shade of resin cement.

PURPOSE: To evaluate the color parameters (CIELab*) after the cementation of ceramic disks of different thicknesses onto a resin substrate using four different shades of resin cements, and determine the color difference (ΔE) between the adhesively cemented disks and a 10 mm-thick A1 shade ceramic control (target color). METHODS: Ceramic disks, simulating laminate veneers, with thicknesses of 0.5, 0.7 and 1.0 mm (shade A1, IPS Classic) were fabricated (n = 40) and cemented with a dual-cured resin cement (Variolink II, shades A1, bleach, opaque and transparent) onto 120 2 mm-thick resin composite substrates (shade A3.5, Adoro). Each ceramic disk was photocured for 80 seconds. The determination of the CIELab* parameters of each ceramic-cement-substrate set was performed with a spectrophotometer. A 10 mm-thick A1 ceramic disk was used as a control. The results for the color difference (ΔE) obtained from L*, a* and b* parameters were analyzed using ANOVA and Tukey's test (α = 0.05). RESULTS: The ΔE values ranged from 2.46 (1.0 mm, opaque cement) to 12.11 (0.5 mm, A1 cement). The opaque cement showed the lower ΔE values, followed by the bleach, transparent and A1 cements. With respect to the thickness of the ceramic, color differences between the target color and the group with 1.0 mm ceramic disks were smaller for all cement shades tested. Only the combination of 1.0 mm ceramic disks cemented with the opaque cement was able to mask the background color (ΔE < 3.7). The color differences between the control and the specimens cemented with opaque resin cement were smaller in comparison with the bleach, transparent and A1 cements.

Esthetic, occlusal, and periodontal rehabilitation of anterior teeth with minimum thickness porcelain laminate veneers.

Ceramic veneers of minimum thickness provide satisfactory esthetic outcomes while preserving the dental structure. Dental ceramics can both improve the esthetic appearance and reestablish the strength and function of teeth. In worn anterior teeth, functional surfaces, for example, anterior and lateral guidance, can be restored effectively. The characteristics of dental ceramics, such as color stability and mechanical and optical properties, make this material a good choice for indirect restorations, especially when optimum function and esthetics are required. This clinical report presents an occlusal, periodontal, and restorative solution with minimum thickness glass ceramic veneers for worn anterior teeth with multiple diastemas.

Bond strength of fiber-reinforced posts to deproteinized root canal dentin.

AIM: This study evaluated the push-out bond strength of cemented fiber posts after deproteinization of root canal dentin walls with NaOCl. The effect of the application of an antioxidant solution (sodium ascorbate) was also evaluated. MATERIALS AND METHODS: A three-step etch-and-rinse (Scotch-bond - 3M Espe) and a one-step self-etching adhesive (Xeno III - Dentsply Caulk) were evaluated. Thirty bovine incisor roots were divided into 3 groups: a. Irrigation with physiologic solution (control). b. Deproteinization with 10 minutes irrigation of 5% NaOCl. c. Deproteinization with NaOCl followed by 10 minutes irrigation with 10% ascorbic acid. Fiber posts were cemented with a dual-cured cement (Rely X ARC - 3M ESPE). The push-out bond strength was evaluated after 24 hours of storage in distilled water. The data were analyzed with three-way ANOVA, one-way ANOVA and Tukey's test (α = 0.05). RESULTS: There were significant differences between groups (p < 0.05). The bond strength of Scotchbond was not influenced by the deproteinization. Xeno III showed a decrease in bond strength when deproteinized with 5% NaOCl (p < 0.05). For Xeno III, the subsequent irrigation with ascorbic acid was able to reverse the effect of the deproteinization. Considering the radicular thirds, the bond strength varied in the sequence-apical < middle < coronal. CONCLUSION: Only the all-in-one adhesive was influenced by the deproteinization. Considering the respective control groups, both systems showed similar bond strength results. CLINICAL SIGNIFICANCE: The decreased bond strength of the self-etching adhesive following deproteinization seams to be related to the oxidant effect of the NaOCl solution and the subsequent irrigation with ascorbic acid was able to reverse the effect of the deproteinization.

Using chemical vapor deposition diamond finishing burs for conservative esthetic procedures.

The article demonstrates how chemical vapor deposition (CVD) diamond burs were used in a simple esthetic and cosmetic procedure to treat discolored anterior teeth. A patient who experienced discoloration after bleaching was treated with direct resin composite veneers. Excess restorative material close to the periodontium was removed with a CVD diamond bur attached to an ultrasonic handpiece. The results indicate that CVD diamond burs are appropriate for removing excess material at the gingival margins of resin composite restorations without damaging the periodontium.

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.

A conservative approach for restoring anterior guidance: a case report.

UNLABELLED: One of the most common dental problems in today's clinics is tooth wear, specifically when related to bruxism. In such cases, the esthetics of anterior teeth may be compromised when excessive wear to the incisal surfaces occurs. Anterior tooth wear resulting from parafunctional bruxism can be conservatively treated with the use of direct resin composite restorations. This restorative approach has the advantages of presenting good predictability, load resistance, acceptable longevity, preservation of healthy dental tissues, and lower cost when compared with indirect restorations. The use of resin composites to solve esthetic problems, however, requires skill and practice. Thus, the present article demonstrates a conservative approach for restoring the esthetics and function of worn anterior teeth with the aid of direct resin composite restorations and selective occlusal adjustment. CLINICAL SIGNIFICANCE: A conservative approach to restore anterior teeth with excessive wear is possible with direct resin composites.

The efficacy of acid etching for removing contamination in layered dental restorations.

Contamination between incremental layers of a composite resin restoration can occur during surgical procedures. The present study sought to evaluate how two decontamination treatments affected the shear bond strength between layers of a saliva-contaminated composite resin surface. Forty disks of a nanohybrid composite resin were prepared and divided into four groups (n = 10). The surfaces of all specimens (except for samples in Group 1, the positive control) were contaminated with human saliva. For the negative control samples (Group 2), no decontamination was performed. For Group 3 samples, acid etching was performed and adhesive was applied. For Group 4, surfaces were roughened with a diamond bur prior to acid etching and adhesive application. The specimens were submitted to a shear bond strength test, and the data were analyzed using one-way ANOVA and Tukey tests (α = 0.05). No significant differences were detected between the mean shear bond strengths of samples in Groups 1, 3, and 4 (p < 0.05). Shear bond strength was significantly reduced in Group 2 samples (p < 0.05). Acid etching and the application of adhesive improved shear bond strength, producing values similar to those in the positive control group.

Esthetic rehabilitation of anterior discolored teeth with lithium disilicate all-ceramic restorations.

The esthetic treatment of darkened anterior teeth represents a great challenge to dentists, because dental materials ideally should match the natural teeth. The optical behavior of the final restoration is determined by the color of the underlying tooth structure, the color of the luting agent, and the thickness and opacity of the ceramic material used. This article reports a case in which veneers and full crowns made of heat-pressed, lithium disilicate glass-ceramic were used for the esthetic rehabilitation of anterior discolored teeth. The patient was referred for treatment with defective anterior composite resin restorations, provisional acrylic resin crowns, darkening of the gingival margins, and uneven gingival contours. The multidisciplinary treatment plan included dental bleaching, periodontal plastic surgery to create gingival symmetry, and indirect all-ceramic restorations using high-opacity lithium disilicate glass-ceramic ingots. The treatment was successful and an excellent esthetic result was achieved.

Undergraduate students introduction to manual and rotary root canal instrumentation.

The aim of this study was to evaluate the performance of undergraduates in their first contact with manual and rotary root canal instrumentation. Forty-two students who had never worked on a root canal before instrumented 42 extracted lower-incisors. Participants were assigned to one of two groups: Rotary instrumentation or manual instrumentation. Pre- and post-operative computed tomography scans were obtained with a 3-dimensional dental imaging system. Starting and finishing times of preparation were recorded. The cross-sectional area of the root canal was analyzed with 2-mm-below-the-apex initial and final transverse images recorded through a digital imaging system and analyzed with software to measure the initial and final area of the root canal in mm(2). Data from the cross-sectional area of the root canal and time spent were subjected to the Mann-Whitney's U-test (p<0.05). The rotary instrumentation group showed smaller time for preparation (p=0.0204). No differences between rotary and manual instrumentation regarding the cross-sectional area of the root canal were observed (p=0.25). No accidents occurred. Undergraduate students showed good performance in their first contact with the manual and rotary instrumentation with regard to time spent and cross-sectional area of the root canal, with no operative accidents.