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This study sought to determine how irradiance at various distances affected the hardness of a new silorane-based composite compared to a methacrylate-based composite resin restorative material. A visible-light curing unit was used at low and high irradiances. Plastic molds of various thicknesses (1, 2, 3, and 4 mm) were filled with composite resin and polymerized for 20 seconds at various distances (0, 2, 4, and 6 mm). After 24 hours of storage at 37°C, the microhardness of each specimen was tested at the bottom surface using a microhardness tester. These microhardness values were expressed as a percentage of maximum microhardness and analyzed with ANOVA and Tukey's post-hoc tests. At both low and high irradiances, the silorane-based composite (shade A2) was capable of acceptable (80%) bottom-to-maximum microhardness ratios at increments up to 3 mm and at curing distances up to 4 mm (at low irradiance) and 6 mm (at high irradiance). [ABSTRACT FROM AUTHOR]

This study sought to determine how repeated applications of a refrigerant spray on various cotton carriers affected the change in pulpal temperature. A thermocouple was placed at the roof of the pulp chamber of a human maxillary canine and connected to a thermometer logging at one-second intervals while the root was immersed in a water bath at 37 degrees C. Four different carrier types were used: large cotton pellets, small cotton pellets, cotton-tip applicators, and cotton rolls. Each carrier was sprayed with 1,1,1,2-tetrafluoroethane and placed on the crown for five seconds. Pulpal temperature change was recorded after each five second application of the same carrier to the tooth until a total of six consecutive sprays and applications of the carrier were applied. Each carrier group consisted of 10 performances of the six sets of readings (n = 10). The difference between baseline and the low temperature reading was calculated to determine the temperature change (in degrees C) in the pulp chamber per application. When the refrigerant spray was used, the large cotton pellet carrier generally produced the largest decrease in pulpal temperature at each repeated application compared to the other types of carriers. However, the same large cotton pellet should not be sprayed with the refrigerant more than two times before it is replaced. [ABSTRACT FROM AUTHOR]

Limited research is available evaluating whether the reported in vitro benefit of immediate dentin sealing (IDS)-namely, increased bond strength to tooth structure-can be acquired in the era of same-day (SD) dentistry. The purpose of this study was to compare the fracture strengths of ceramic overlays fabricated with a delayed dentin sealing (DDS) technique or an IDS technique under 1-hour SD or 2-week multiple-day (MD) delivery conditions. Forty extracted, healthy maxillary third molars were prepared for a lithium disilicate overlay restoration and divided into 4 groups of 10 teeth each. In the SD-DDS group, the teeth were prepared and then stored for 1 hour in artificial saliva, and the adhesion protocol (bonding agent and resin cement) was applied at the time of delivery of the ceramic overlay. In the SD-IDS group, the teeth were prepared, the adhesive protocol was applied immediately, and the teeth were stored for 1 hour before delivery of the overlay. The protocols for the MD-DDS and MD-IDS groups were identical to SD-DDS and SD-IDS, respectively, except that the teeth were provisionalized and stored for 2 weeks prior to delivery of the overlay. Specimens were thermocycled and subjected to cyclic functional loading before they were loaded to failure in a universal testing machine using a rod resting on the buccal incline of the palatal cusp. Two-way analysis of variance tests revealed no statistically significant differences in fracture strength between the groups based on dentin sealing (P = 0.331) or delivery time (P = 0.314). The specimens demonstrated 2 fracture types; either a portion of the ceramic cohesively fractured, leaving the tooth intact, or the ceramic and part of the tooth fractured. There were no instances in which the restoration itself delaminated during fracture testing. A Kruskal-Wallis test indicated there were no statistically significant differences in fracture modes between the groups. In this in vitro study, IDS did not provide a significant increase in the fracture strength of overlay restorations compared with DDS, regardless of whether the restorations were delivered the same day or after 2 weeks of storage., Competing Interests: No conflicts of interest reported.

The purpose of this study was to evaluate the accuracy of an intraoral scanner based on camera sleeve type, decontamination protocol, and calibration status. Five extracted human teeth were set into a gypsum stone model and prepared for various indirect restorations. An optical impression was completed with a benchtop scanner to serve as a reference standard. A total of 160 optical impressions were completed using a sterilizable sleeve, an autoclavable sleeve with a single-use plastic window, or a single-use disposable plastic sleeve attached to a calibrated or an uncalibrated intraoral scanner. For the sterilizable sleeves, 2 decontamination protocols were used--high-level disinfection (HLD) or dry heat sterilization (DHS)--and scans were performed at baseline and after 25 and 50 cycles for each protocol. For the autoclavable (AS) and disposable single-use (SU) sleeves, scans were performed at baseline only. Thus, there were 10 optical impressions per test condition: sleeve type (HLD, DHS, AS, or SU) × decontamination status (baseline, 25 cycles [HLD or DHS], or 50 cycles [HLD or DHS]) × calibration status (calibrated or uncalibrated scanner). The individual optical impressions were compared to the reference standard impression by using 3-dimensional best-fit superimposition with the prepared tooth surfaces as reference points, and 3-dimensional linear differences were calculated for each superimposition. The median positive and absolute value median negative distance measurements were averaged for each impression to generate an average median discrepancy from baseline. The data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). No statistically significant differences in the median linear distance were found, regardless of sleeve type, decontamination protocol, or calibration status (P > 0.05). All groups demonstrated statistically similar linear disparities, ranging from 11.78 to 14.00 μm. The most precise sleeves were the single-use plastic sleeves, although their results were not significantly different from those of the multiuse sleeve. The results indicated that any of the currently available camera sleeves can provide similar accuracy in a clinical setting and that single-use disposable sleeves are a viable alternative to the currently accepted multiuse sleeves., Competing Interests: No conflicts of interest reported.

The dental setting is regarded as a high-risk environment for aerosol concentrations and transmission of respiratory infectious agents, especially in relation to the COVID-19 pandemic. Although a number of approaches and practices have evolved to reduce the spread of pathogens in the dental setting, the risk of airborne infection remains a concern. Several new extraoral suction (EOS) devices have been marketed recently; further investigation is warranted to determine their clinical effectiveness. The aim of this study was to evaluate the efficacy of a chairside EOS device (PAX 2000 Extraoral Dental Suction System) in reducing aerosol contamination from patients receiving ultrasonic scaling by a registered hygienist as a part of initial or supportive periodontal therapy. The number of colony-forming units (CFUs) was measured with agar plates before, during, and after ultrasonic scaling at 3 different locations in the dental operatory (instrument table, patient chest area, and patient foot area). Forty subjects were randomly allocated into 2 test groups (n = 20) in which ultrasonic scaling was performed with or without the use of the EOS device. The CFUs retrieved after incubation were quantified and identified by their bacterial or fungal taxon. The use of the EOS device reduced the number of CFUs during scaling at all 3 locations, but the difference was only statistically significant (P = 0.018; Mann-Whitney U test) at the patient's chest area, where the highest number of CFUs was present. The aerosols consisted of 74 different taxa of human origin. The results suggest that the tested EOS system may reduce aerosol contamination in the clinical dental setting, especially in proximity to the patient's head, where most aerosols are generated., Competing Interests: No conflicts of interest reported.

The purpose of this study was to compare the performances of 5 different instruments in measuring the irradiance of light-curing units (LCUs). A novel spectrometer-trained radiometer (CheckUp), 2 conventional chairside radiometers (Bluephase Meter I and Bluephase Meter II), and 2 devices considered to be gold standards for measuring irradiance (an integrating sphere spectrometer and a thermopile sensor) were used to evaluate 7 LCUs. The irradiance of each LCU was measured 10 times with each meter. Data were analyzed using linear regression analysis and a 1-way analysis of variance with Tukey post hoc test (α = 0.05). The mean irradiance values of the LCUs differed significantly depending on which meter was used for measurement (P < 0.05). Bivariate regression analysis demonstrated that the highest correlations in the irradiance values were found between the CheckUp meter and both the integrating sphere (r 2 = 0.980) and the thermopile (r 2 = 0.933). The absolute mean (SD) percentage deviation between irradiance measured by the CheckUp instrument and irradiance measured by the other meters was 7.2% (2.0%) for the integrating sphere, 7.0% (3.6%) for the thermopile, 21.5% (16.1%) for Bluephase Meter I, and 13.1% (7.1%) for Bluephase Meter II. Compared with the 2 conventional chairside radiometers, the CheckUp meter provided the highest correlation with and lowest absolute percentage deviation from the irradiance measured by the gold standard spectrometers., Competing Interests: No conflicts of interest reported.

While evidence shows that dental erosion (DE) is often caused by gastroesophageal reflux disease (GERD), the relationship of DE severity to a patient's symptoms and receipt of appropriate medical treatment for GERD is not clearly understood. The purpose of this study was to evaluate the association between DE and GERD. Eighty participants underwent a Basic Erosive Wear Examination for DE and completed the Patient-Reported Outcomes Measurement Information System (PROMIS) survey on symptoms of gastrointestinal reflux (PROMIS Scale v1.0, Gastrointestinal Gastroesophageal Reflux 13a) in English. Patients with observed erosive patterns were referred for gastroenterologic evaluation. The association between DE and GERD was assessed using multiple regression. The results showed that the extent of DE was positively associated with GERD symptoms (B = 0.585; 95% CI, 0.21-0.96), as measured by the PROMIS survey, in participants without a current diagnosis of GERD. Of the 80 patients in the study, 28 with more severe DE were evaluated in the gastroenterology department. A diagnosis of GERD was established for 27 of the 28, 9 of whom denied a past history of the disease. Twenty patients with GERD underwent upper endoscopy, and esophageal lesions were found in 6 patients (erosive esophagitis in 5 and Barrett esophagus in 1). Patients with clinically identified DE may benefit from medical evaluation and, if necessary, management of GERD. For a subset of patients, DE may be the only clinical indication of untreated or undertreated GERD, which could lead to serious esophageal changes. Dentists should consider referring patients with DE to primary care providers or gastrointestinal specialists to ensure that systemic conditions are identified and managed appropriately., Competing Interests: The views expressed are those of the authors and do not reflect the official views or policy of the Uniformed Services University, US Department of Defense, or its components. The authors do not have any financial interest in any companies discussed in this manuscript.

Limited research has been published evaluating the failure of zirconia crowns with less retentive tooth preparations. The purpose of this study was to evaluate the effect of axial wall height (AWH) and cement type on the fracture load of cubic phase-containing zirconia crowns. Standardized crown preparations with an AWH of 0, 2, or 4 mm (n = 10) were made in 90 extracted human maxillary third molars. The preparations were scanned, and crown restorations were designed. Cubic phase-containing zirconia crowns were milled and cemented with a resin-modified glass ionomer cement, a self-adhesive resin cement, or an adhesive resin cement. The specimens were subjected to thermocycling and cyclic loading. Each crown specimen was positioned in a universal testing machine so that the long axis of the tooth was at a 60° angle to the testing fixture and loaded until failure using a stainless steel rod resting on the buccal incline of the palatal cusp. Data were found to have a nonnormal distribution and were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Statistically significant differences in the median fracture loads of the groups were found based on both AWH and cement type (P < 0.05). Regardless of cement type, the median fracture loads were significantly lower in the 0-mm AWH groups than in the 2-mm and 4-mm AWH groups, which were not significantly different from each other. Compared to the other cement types, adhesive resin cement resulted in a significantly greater median fracture load when the AWH was 0 mm. The use of an adhesive resin cement with a cubic phase-containing zirconia crown may provide greater fracture resistance for preparations with minimal AWH., Competing Interests: The views expressed are those of the authors and do not reflect the official views or policy of the Uniformed Services University, US Department of Defense, or its components. The authors do not have any financial interest in the companies whose materials are discussed in this manuscript.

The objective of this study was to evaluate the efficacy of various decontamination methods and subsequent sterilization on contaminated and inoculated diamond-coated burs. One hundred forty new diamond-coated burs and 120 extracted human molars were utilized in this study. The burs were divided into 7 groups (n = 20): 1, positive control; 2, negative control; 3, new, unused burs; and 4 to 7, burs subjected to various combinations of cleaning methods (manual cleaning, use of a cleaning stone, and/or ultrasonic cleaning) after contamination. In all of the groups except group 3, the burs were sterilized and used to abrade the enamel and dentin of the sterilized extracted teeth. In groups 1 and 4 to 7, the burs were subsequently inoculated with 1 of the following microorganisms: Enterococcus faecalis (ATCC 19433), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 15442), or Geobacillus stearothermophilus (ATCC 7953). Twenty-four hours after inoculation, the burs in group 2 and groups 4 to 7 were subjected to the cleaning treatments and sterilized with steam. The burs in all 7 groups were then cultured for bacterial contamination. No growth of any bacterial type was observed in any of the groups except the positive control group. The use of a cleaning stone in combination with manual or ultrasonic cleaning resulted in the least amount of remaining tooth debris on the diamond-coated burs. The contaminated and inoculated diamond-coated burs tested in this study were successfully sterilized, and the tested bacteria were eliminated. If using a diamond-coated bur multiple times, practitioners should consider utilizing debridement with a cleaning stone followed by either manual or ultrasonic cleaning and then by a single cycle of steam sterilization., Competing Interests: The views expressed are those of the authors and do not reflect the official views or policies of the Uniformed Services University, US Air Force, Department of Defense, or US government. The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article.

The reported advantage of new dual-cured adhesive agents is that they do not require light curing, resulting in a reduced film thickness and improved seating of bonded all-ceramic restorations. The purpose of this study was to determine the effect of dual-cured adhesives on the bond strength of dual-cured resin cement to dentin under different polymerization conditions: with or without light curing of the dual-cured adhesive as well as with or without light curing of the dual-cured resin cement through a lithium disilicate ceramic material. Human molars were sectioned to remove the coronal tooth structure and randomly divided into 3 adhesive groups: Clearfil SE Bond 2, ExciTE F DSC, and Universal Primer. The adhesive agents were applied to the dentin surface with or without light activation. A dual-cured resin cement was applied, and discs of lithium disilicate were cemented to the dentin surface. Half of the discs were light cured from the top surface, and the other half were allowed to self-cure. Shear bond strength was tested after storage in distilled water for 24 hours. The effect of light curing of the adhesive or cement on the shear bond strength of the lithium disilicate discs to dentin was product dependent. Clearfil SE Bond 2 performed significantly better with light curing of both the adhesive and cement. Less significant effects of the various light-curing and self-curing combinations were observed with ExciTE F DSC or Universal Primer. When neither the adhesive nor the cement was light cured, all 3 adhesives performed poorly and had a significant loss in bond strength., Competing Interests: The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article. The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, the Department of Defense, Uniformed Services University of the Health Sciences, or the US government.

Digital dentistry has led to the success of same-day, single-crown delivery. Unlike traditional convection furnaces for fabrication of zirconia materials, which typically require several hours to complete sintering, a dedicated high-speed sintering furnace that reportedly sinters zirconia in minutes is now available. Sintering times may increase or decrease based on the size of the restoration due to a novel interface between the chairside acquisition unit, milling unit, and furnace. The purpose of this study was to compare the flexural properties (strength and modulus), optical parameters (translucency and opalescence), and grain size of a full-contour tetragonal zirconia material after sintering in either a novel high-speed furnace or a conventional zirconia furnace. Rectangular zirconia beams were milled and sintered using the high-speed induction furnace for 26.2 minutes or a conventional convection furnace for 4.3 hours. Flexural strength and modulus were determined by subjecting the beams to a 3-point bending test in a materials testing machine. Translucency and opalescence were calculated using a spectrophotometer, and grain size was determined by using an atomic force microscope. The dedicated high-speed induction furnace sintered the tetragonal zirconia specimens in substantially less time than the conventional convection furnace, with a statistically significant decrease in grain size and no significant difference in strength or optical properties., Competing Interests: Dentsply Sirona loaned the SpeedFire furnace used in this study as part of a Material Transfer Agreement with the US Air Force. The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, the Department of Defense, Uniformed Services University of the Health Sciences, or the US government. The authors do not have any financial interest in the companies whose materials are discussed in this article.

New ceramic-polymer millable materials that may be less resistant to the abrasive effects of toothbrushing than glass-ceramic materials have been introduced recently. The purpose of this study was to evaluate the polish retention of ceramic-polymer materials after mechanical toothbrush abrasion. Four ceramic-polymer materials (Enamic, Lava Ultimate, CeraSmart, and Block HC) were compared to a lithium disilicate glass-ceramic material (IPS e.max CAD). After 10 specimens of each material were polished, baseline area surface roughness (Sa) measurements were made. Specimens were then placed in a toothbrushing machine for 60,000 strokes, simulating 8 years of brushing. Surface roughness measurements were repeated after 30,000 and 60,000 brush strokes. At the end of the brushing, IPS e.max CAD and Enamic had the lowest mean Sa values (0.50 [SD 0.17] and 0.55 [0.13] µm², respectively), while Block HC had the greatest (1.10 [0.10] µm²). Lava Ultimate and CeraSmart demonstrated intermediate Sa values (0.81 [0.14] and 0.72 [0.11] µm², respectively). Only IPS e.max CAD had no statistically significant increase in surface roughness after toothbrushing., Competing Interests: Disclaimer: The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, the Department of Defense, Uniformed Services University of the Health Sciences, or the United States government. The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article.

Manufacturers have recently introduced surface primers and pretreatment solutions that reportedly simplify the bonding process of resin cements to ceramics through various combinations of etchant and coupling agents. This study evaluated the shear bond strength (SBS) of a resin cement to a lithium disilicate glass-ceramic material pretreated with various new surface treatment solutions and compared the results to those of a control group prepared with the traditional application of hydrofluoric acid (HF) and silane. Resin cement was bonded to pretreated glass-ceramic surfaces, and specimens were tested for SBS after 24 hours of storage in water. Traditional surface treatment of lithium disilicate glass ceramic with HF and silane resulted in a significantly greater mean SBS than did simplified primer solutions. There were no statistically significant differences among the simplified pretreatment groups. In the control group, the majority of failures were due to mixed adhesive-cohesive fracture, while in the simplified treatment groups the failure mode was usually adhesive, suggesting a weaker interface., Competing Interests: Disclaimer: The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, the Department of Defense, Uniformed Services University of the Health Sciences, or the US government. The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article.

The purpose of this study was to evaluate the fracture resistance of teeth with standard or extended mesio-occlusodistal (MOD) preparations after restoration with bonded computer-aided design/computer-aided manufacturing (CAD/CAM) materials. Standard or extended MOD cavities were prepared in 60 of 70 extracted, caries-free third molars. In the standard MOD preparations (n = 30), 4.5- mm buccal and lingual/palatal wall thickness remained, and proximal boxes extended 1.0 mm coronal to the cementoenamel junction. In the extended MOD preparations (n = 30), the buccal and lingual/palatal walls were reduced to a thickness of 3.0 mm. A CAD/CAM acquisition unit was used to scan 20 standard and 20 extended preparations. Subsequently, 10 standard and 10 extended preparations were restored with milled lithium disilicate, and 10 of each type were restored with resin nanoceramic. Ten of each preparation type were left unrestored (negative control). An additional 10 third molars were neither prepared nor restored (positive control). After thermocycling and cyclic loading, specimens were fractured in a material testing device. Although bonded CAD/CAM restorations reinforced the tooth structure, the mean fracture loads were significantly lower (P < 0.05) in teeth with restored extended preparations (2642.4 [SD 479.4] N) than in teeth with restored standard preparations (3376.6 [SD 817.9] N). The type of CAD/CAM restorative material did not significantly affect the fracture load. Practitioners should consider covering the cusps with a CAD/CAM restorative material to reduce the potential for fracture in preparations with reduced cuspal thickness, especially in patients with heavier occlusion or functional loads., Competing Interests: Disclaimer: The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, Department of Defense, Uniformed Services University of the Health Sciences, or US government. The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article.

The purpose of this study was to compare the depths of cure of a proximal box preparation filled in bulk with various approaches: filled with a bulk-fill or conventional composite; placed with a new perforated metal matrix, a traditional metal matrix, or a clear matrix; and polymerized with either occlusal-only or tri-sited light curing. After tri-sited curing, the use of the new perforated metal matrix band resulted in a depth of cure that was not significantly different from that achieved with the use of metal bands (removed during curing) or transparent matrix bands. Adequate polymerization was obtained at depths of more than 5.0 mm for the bulk-fill composite and more than 4.0 mm for the conventional composite when tri-sited light curing was used. Tri-sited light curing resulted in a significantly greater depth of cure than occlusal-only curing. The perforated metal band may be used as an alternative to the use of solid metal bands or transparent matrix bands to provide similar depths of cure for composite resins, with the possible benefits of malleability and the ability to leave the band in place during tri-sited light curing., Competing Interests: Disclaimer: The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, the Department of Defense, Uniformed Services University of the Health Sciences, or the US government. The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article.

A new fluoride-releasing sealant system is claimed to allow easier and faster placement while providing high bond strengths without the need for phosphoric acid etching. A study was designed to compare the microleakage and shear bond strength of a self-etching, Giomer-based sealant system with those of a traditional resin sealant. Group 1 received traditional sealant applied after use of a 35% phosphoric acid etchant; group 2 received Giomer sealant after use of a self-etching primer; and group 3 received Giomer sealant after the addition of an initial phosphoric acid etching step and placement of the primer. The sealants were placed in the occlusal pits and fissures of extracted human third molars, thermocycled, placed in dye, and sectioned. The extent of microleakage (dye penetration) was expressed as a percentage of the cross-sectional length of the sealed interface. The sealants were also bonded to the facial enamel of bovine incisors. Specimens were thermocycled and tested in shear mode in a universal testing machine. The new self-etching sealant demonstrated significantly greater microleakage (P < 0.017) and lower bond strength (P < 0.05) than both the traditional sealant system and the new system when placed with phosphoric acid etchant. Phosphoric acid etching significantly improved the shear bond strength and reduced the microleakage of the new sealant., Competing Interests: Disclaimer: The views expressed in this article are those of the authors and do not reflect the official policy of the US Air Force, the Department of Defense, the Uniformed Services University of the Health Sciences, or the US government. The authors do not have any financial interest in the companies whose materials are discussed in this article.

The purpose of this study was to evaluate the translucency and strength of highly translucent monolithic zirconia ceramic materials recently introduced to the market. Four monolithic zirconium oxide materials promoted as having high translucency (BruxZir Shaded 16, BruxZir HT, Lava Plus, and inCoris TZI C) were compared to a high-translucency, lithium disilicate monolithic glass-ceramic material (IPS e.max CAD HT). To evaluate translucency, the materials were sectioned into 0.5-, 1.0-, 1.5-, and 2.0-mm-thick specimens; all were sintered and polished. Translucency parameters were calculated with a spectrophotometer. To evaluate flexural strength and modulus, the ceramic materials were sectioned to create beams and fractured in a universal testing machine. The lithium disilicate had significantly greater translucency than the zirconia materials at each thickness. In general, the translucencies of the zirconia materials were similar at each thickness. However, at the manufacturers' recommended minimal thicknesses, 0.5-mm specimens of BruxZir Shaded 16, inCoris TZI C, and Lava Plus were more translucent than the 1.0-mm-thick specimens of IPS e.max CAD HT. Translucency significantly decreased for each material at each increase in thickness. The flexural strengths of the zirconia materials were similar to each other and significantly greater than that of IPS e.max CAD HT. Flexural moduli were more variable. Of the zirconia materials, BruxZir Shaded 16 had an overall better combination of translucency, strength, and modulus.

The study evaluated the effect of salivary-contaminant removal methods on the bond strength of resin cement to hydrofluoric acid-etched ceramic. Treatment with a new cleaning paste resulted in bond strengths not significantly different from those obtained in phosphoric acid-treated, hydrofluoric acid-treated, and uncontaminated control groups; thus the paste may be considered an alternative to phosphoric acid or hydrofluoric acid for removal of salivary contaminants.

The purpose of this study was to compare the properties of 2 new dual-cure, bulk-fill restorative composite resins to those of a hybrid composite resin material. Depth of cure, fracture toughness, porosity, microleakage, and volumetric shrinkage properties were examined. With the exception of fracture toughness, significant differences were found among materials. Compared to the incrementally placed hybrid composite, the dual-cure, bulk-fill restorative composites in self-cured mode had unlimited depth of cure, similar fracture toughness and porosity formation, and greater polymerization shrinkage and microleakage.

The mechanical properties of pulp-capping materials may affect their resistance to fracture during placement of a final restorative material or while supporting an overlying restoration over time. The purpose of this study was to compare the compressive strength, flexural strength, and flexural modulus of 2 new pulp-capping materials (TheraCal LC and Biodentine), mineral trioxide aggregate (MTA), and calcium hydroxide over time. Specimens were created in molds and tested to failure in a universal testing machine after 15 minutes, 3 hours, and 24 hours. The MTA specimens did not set at 15 minutes. At all time periods, TheraCal LC had the greatest compressive and flexural strengths. After 3 and 24 hours, Biodentine had the greatest flexural modulus. TheraCal LC had greater early strength to potentially resist fracture during immediate placement of a final restorative material. Biodentine had greater stiffness after 3 hours to potentially provide better support of an overlying restoration under function over time.

The purpose of this double-blind, split-mouth, randomized human clinical study was to evaluate the effectiveness of a new sodium bicarbonate local anesthetic buffering device (Onset) in reducing pain associated with dental injections. Twenty patients were given bilateral inferior alveolar (IA) and long buccal (LB) nerve block injections and asked to quantify the pain experienced during injection on a visual analog scale (0, no pain; 10, worst possible pain). One side of the mouth received standard-of-care injections of 2% lidocaine with 1:100,000 epinephrine. On the opposite side, after the buffering device was used to mix the components within the anesthetic carpule, patients received injections of 2% lidocaine with 1:100,000 epinephrine buffered 9:1 with 8.4% sodium bicarbonate. The mean pain scores were 2.7 (SD, 1.3) for buffered and 2.7 (SD, 1.9) for unbuffered IA injections. The mean pain scores were 2.0 (SD, 1.4) for buffered and 2.7 (SD, 1.8) for unbuffered LB injections. The data were analyzed with a paired t test (α = 0.05), and no statistically significant difference was found between groups for IA (P = 0.94) or LB (P = 0.17) nerve block injections. In this study of patients receiving common dental nerve block injections, local anesthetic buffering technology did not significantly lessen pain compared to that experienced during a standard unbuffered injection.

In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

A new nanohybrid composite activated by sonic energy has been recently introduced as a single-step, bulk-fill restorative material. The purpose of this study was to compare the physical properties of this new composite to various other composite restorative materials marketed for posterior or bulk-fill placement. The following physical properties were examined: depth of cure, volumetric shrinkage, flexural strength, flexural modulus, fracture toughness, and percent porosity. A mean and standard deviation were determined per group. One-way ANOVA and Tukey's post hoc tests were performed per property (α = 0.05). Percent porosity was evaluated with a Kruskal-Wallis/Mann-Whitney test (α = 0.005). Significant differences were found between groups (P < 0.001) per test type. Compared to the other composite restorative materials, the new nanohybrid composite showed low shrinkage and percent porosity, moderate fracture toughness and flexural modulus, and high flexural strength. However, it also demonstrated a relatively reduced depth of cure compared to the other composites.

This study sought to determine the effect of cyclic loading and toothbrush abrasion (with and without abrasive slurries) on cervical lesion formation. The roots of extracted human third molars were embedded in acrylic resin, leaving 2 mm of root structure and crowns exposed. Teeth were divided into 6 groups (n = 10) with the following treatments: no treatment (control), cyclic load in distilled water, brushing with distilled water, cyclic load followed by brushing with distilled water, brushing with toothpaste slurry, and cyclic load followed by brushing with toothpaste slurry. Cyclic loading and toothbrushing machines subjected the teeth to 1.6 million cyclic loads and 30,000 brushing strokes, the equivalent of 4 years of function and brushing for an average patient. The teeth were scanned with a 3-dimensional optical profilometer to determine the volumetric loss of tooth structure. Load cycling had no significant effect on cervical tooth loss. Brushing with toothpaste resulted in significantly greater cervical tooth loss than brushing with water, which in turn was significantly greater than no treatment at all.

The application and incomplete removal of a computer-aided design/computer-aided manufacture imaging powder may affect the dentin surface prior to bonding a ceramic restoration. The purpose of this study was to compare the effect of imaging powder residue on the shear bond strength of a self-adhesive resin cement to dentin. Mounted human third molars were sectioned coronally with a diamond saw to expose the dentin, which was then prepared with a diamond bur mounted in a custom jig. The dentin surface was sprayed with 3 different imaging powders. The 3 powder groups were then divided into 3 subgroups based on the method of powder removal: no rinse, 1-second rinse, and 10-second rinse. A control group was created that had no application of imaging powder. A self-adhesive resin cement was bonded to the surfaces and loaded to failure in a universal testing machine after 24 hours of storage. Data was analyzed with Kruskal-Wallis and Mann-Whitney nonparametric tests. The bonding to dentin surfaces of the powder groups that were rinsed for 1 or 10 seconds were not significantly different from each other or the nonpowdered control. The type of imaging powder did not significantly affect the bond strength. The nonrinsed powdered dentin surface had a significant reduction in bond strength compared to both the control and the rinsed powdered surfaces.

The purpose of this study was to determine the efficacy of toothbrushes that advertise self-disinfecting, antimicrobial properties due to the inclusion of silver nanoparticles or chlorhexidine in the bristles. Three different types of toothbrushes-silver nanoparticle, chlorhexidine-coated, and a control-were submerged in suspensions of Streptococcus mutans and Candida albicans. At designated times postinoculation, organisms were removed from the toothbrush heads, then serially diluted, plated, and incubated. The colony-forming units (CFUs) were counted and a mean percent reduction was determined for each organism group. With the S. mutans groups, the chlorhexidine-coated toothbrushes had significantly greater percent reduction in CFUs at all 3 time points compared to the control or silver nanoparticle toothbrushes. With the C. albicans groups, neither the chlorhexidine-coated nor the silver nanoparticle toothbrushes had a significant reduction in CFUs compared to the control. Neither of the antimicrobial toothbrushes delivered the advertised claim of a 99.9% reduction in CFUs with either microorganism. However, the inclusion of chlorhexidine in toothbrush bristles appeared to be the most promising of the methods tested for toothbrush self-disinfection.

This study evaluated how preheating affected the properties of a silorane-based composite restorative material and 4 methacrylate-based composites. Viscosity, compressive strength, depth of cure, and polymerization shrinkage were examined. Data were analyzed with a 2-way ANOVA per physical property and composite type. With the exception of the flowable composite, significant reductions in viscosity were found between all preheated and room temperature composites, with no significant difference in other properties. In general, preheating the restorative composites decreased viscosity, but did not affect compressive strength, depth of cure, or shrinkage per composite type.

This study evaluated the shear-bond strength of a resin-modified glass ionomer (RMGI) restorative material to a new silorane-based composite and a methacrylate-based composite in a sandwich technique with various combinations of surface treatments and bonding agents. Two composites, 2 bonding agents and 4 surface preparations were used to create 16 groups with 10 specimens each. After 24 hours storage at 37°C in 100% humidity, the specimens were tested for shear bond strength; means and standard deviations were determined per group. Surface modifications did not affect the shear-bond strength of the silorane or methacrylate composites to the RMGI. The new silorane composite had significantly lower bond strength to the RMGI compared to the methacrylate composite. The new silorane system adhesive agent had significantly higher bond strength to the RMGI compared to the methacrylate adhesive agent. The greatest bond strengths to the RMGI were produced when using the silorane system adhesive agent with the methacrylate composite.

New ceramic primers, which reportedly enhance bonding of resin cements to zirconia, have been marketed recently. The purpose of this study was to compare the shear bond strength of 3 resin cements to zirconia conditioned with 4 ceramic primers. Zirconia blocks were conditioned with 4 different primers (Z-Prime Plus, MonoBond Plus, CLEARFIL CERAMIC PRIMER, and AZ Primer) or no primer (control). The zirconia blocks were placed in a jig, and 1 of 3 resin cements (Multilink Automix, RelyX Unicem, Panavia F 2.0) were mixed, injected into a mold, and light cured. The specimens were tested in shear on a universal testing machine after 24 hours of storage in distilled water. The shear bond strength of the resin cements to zirconia varied based on the type of primer. Z-Prime Plus provided the highest shear bond strength to zirconia, and was significantly greater than the control (no primer) with all 3 resin cements.

A paste-paste resin-modified glass ionomer (RMGI) restorative material has been introduced recently with a new conditioner that requires no rinsing. The purpose of this study was to compare the shear bond strength of an encapsulated RMGI (Fuji II LC) and a new paste-paste RMGI (Fuji Filling LC) to dentin conditioned with 20% polyacrylic acid (Cavity Conditioner), a new no-rinse conditioner (Self Conditioner,), or no conditioner. Mounted human third molars were flattened and the dentin surface was conditioned. The RMGI restorative materials were mixed and incrementally inserted into a mold and photocured. The specimens were loaded until failure in a universal testing machine after 24 hours of storage in distilled water. Fuji II LC had significantly greater bond strength to dentin than Fuji Filling LC. The use of Cavity Conditioner or Self Conditioner resulted in bond strengths that were not significantly different from each other; however, both produced greater bond strengths than those in the non-conditioned groups.

Conscious sedation has become an integral part of dentistry; it is often used to reduce anxiety or fear in some patients during oral surgery, periodontal surgery, implant placement, and general dentistry procedures. The purpose of this study was to evaluate the frequency of adverse events during IV conscious sedation provided by credentialed general dentists and periodontists in the United States Air Force (USAF). Sedation clinical records (Air Force Form 1417) from calendar year 2009 were requested from all USAF bases. A total of 1,468 records were reviewed and 19 adverse events were noted in 17 patients. IV complication (infiltration) was the most common adverse event. The overall adverse event rate was 1.3 per 100 patients treated. The results of this study show that moderate sedation provided by general dentists and periodontists in the USAF has a low incidence of adverse events, and conscious sedation remains a viable option for providers for the reduction of anxiety in select patients.

Filtek LS is a new composite resin restorative system with a unique, low-shrinking, silorane-based monomer matrix. The current study was conducted to compare the durability of the bond to dentin of the new silorane-based bonding agent, Filtek Silorane System Adhesive, to the gold standard methacrylate-based bonding agent, Clearfil SE Bond. Extracted human molar teeth were sectioned to expose dentin. Either Filtek Silorane System Adhesive with Filtek LS composite or Clearfil SE Bond with Clearfil Majesty Posterior composite was applied to the dentin according to the manufacturer's instructions. The composites were placed incrementally and sectioned perpendicular to the composite-tooth interface to obtain rectangular beams. The beams were stored for 24 hours, 6 months, or 12 months in distilled water and stressed in tension in a universal testing machine. Data were analyzed with a two-way ANOVA/Tukey test. The 24-hour microtensile bond strengths were significantly greater than the 6- and 12-month bond strengths. Overall, there was no significant difference in the microtensile bond strength to dentin between the Filtek Silorane System Adhesive and the Clearfil SE Bond adhesive bonding agents. After one year of water storage, the new silorane-based composite resin bonding agent performed as well as the methacrylate-based composite resin bonding agent.

Recently, new self-adhesive flowable composite resin systems have been introduced to the market. These new composite resin systems reportedly bond to dentin and enamel without the application of an adhesive bonding agent. The purpose of this study was to evaluate the shear bond strength to enamel of two new self-adhesive flowable composites with and without the use of an etch-and-rinse bonding agent. The new self-adhesive flowable composites had significantly lower bond strengths to enamel compared to a traditional adhesively bonded flowable composite. Both self-adhesive flowable composites had a significant increase in bond strength to enamel with the use of a phosphoric acid-etch and adhesive bonding agent.

This study sought to determine the difference in color stability of resin cements after one year of storage in water. Three commercial resin cements (Nexus 3, Calibra, Variolink 2) were evaluated under three different curing conditions (photo-, dual-, and self-cure) over three storage time periods (3, 6, and 12 months). A plastic mold was used to prepare cylindrical specimens of each of the three resin cements. For the phototcured specimens, only the base component of the resin cement was cured. For the dual- and self-cure specimens, the base and catalyst of the cements were mixed according to the manufacturer's instructions, syringed into the mold, and either photocured as before (dual-cure) or allowed to chemically set (self-cure). The total amount of color change (delta E) was calculated using a spectrophotometer after 24 hours (baseline) and after 3, 6, and 12 months of storage in distilled water. Data were analyzed using a repeated measures ANOVA and a Tukey test. After one year of storage, Nexus 3 demonstated the lowest color change values (delta E) under all curing conditions, although it was not significantly different from Variolink 2 when photocured or Calibra when self-cured. New resin cements without a traditional benzoyl peroxide/amine redox initiator system, such as Nexus 3, could be more color-stable over time.

The purpose of this study was to compare the microleakage of a new self-etch sealant (Enamel Loc), with and without acid etching, to a traditional sealant (UltraSeal XT Plus) with acid etching in occlusal fissures. The self-etch sealant had significantly more microleakage than the traditional sealant or the self-etch sealant with acid-etching of the enamel.

Approximately 18 percent of all permanent teeth have Class V lesions. In addition, the prolonged retention of teeth in an increasingly older population is expected to increase the prevalence of Class V lesions. Much has been written about the merits of various techniques for restoring such lesions, but little information is available comparing and contrasting all the material and procedural options available to the general dentist. Etiologies, indications for treatment, and restorative materials are discussed to provide guidance in planning treatment. A diagnostic decision tree is proposed for this dynamic area of restorative dentistry.