A randomized, controlled, two-month pilot trial of stannous fluoride dentifrice versus sodium fluoride dentifrice after oxalate treatment for dentinal hypersensitivity.

OBJECTIVES: To compare the effects of a stannous fluoride dentifrice and a sodium fluoride dentifrice on dentinal hypersensitivity when used with an oxalate-based regimen combining in-office and at-home treatment. MATERIALS AND METHODS: In this single-center, randomized, controlled, double-blind, pilot clinical trial, 30 subjects were professionally treated at baseline with a 3% oxalate/potassium salt solution on up to two target teeth, then randomized 1:1 to either 0.454% stannous fluoride or 0.243% sodium fluoride overlabeled dentifrice. Both groups were given 6 sensitivity strips (3.14% potassium oxalate gel) and a soft, manual toothbrush. Subjects were permitted to apply strips on up to two teeth, up to three times per tooth, at home as desired throughout the study. Dentinal sensitivity (cold air blast challenge) was assessed at baseline, immediately after post-professional treatment, and at day 60 using the Schiff scale and a Visual Analog Scale (VAS). RESULTS: Immediately after professional oxalate treatment, the overall mean Schiff and VAS score decreased 25.6% and 22.4% from baseline, respectively (p ≤ 0.001 for both). At day 60, further reductions in both mean scores were seen in both groups. There were no significant differences between the groups at day 60. All treatments were well tolerated. CONCLUSIONS: In subjects treated with oxalates for dentinal hypersensitivity, both stannous fluoride and sodium fluoride dentifrices are well tolerated, are feasible for routine use, and do not detract from the desensitizing effects of an in-office and at-home oxalate combination treatment regimen. CLINICAL RELEVANCE: Either stannous fluoride or sodium fluoride dentifrices can be recommended to dentinal hypersensitivity patients who undergo professional oxalate treatment.

A randomized, controlled comparison of two professional dentin desensitizing agents immediately post-treatment and 2 months post-treatment.

PURPOSE: To compare the desensitizing effects of two different marketed professional dentin hypersensitivity treatments, a 5% sodium fluoride varnish and an oxalic acid/potassium salt solution, in a single-center, randomized, controlled, subject-blind pilot study. METHODS: A total of 22 subjects with dentin hypersensitivity on at least two teeth were recruited from a general dentistry practice and randomized 1:1 to treatment with a 5% sodium fluoride varnish (Acclean Fluoride Varnish) group or a 3% oxalic acid/potassium salt solution (Super Seal Desensitizer). The study population was predominantly female (91%) and Caucasian (77%). The mean age was 46.4 years, with ages ranging from 18-73 years. Dentin hypersensitivity was assessed after an air blast challenge by the examiner (Schiff Index Sensitivity Scale) and by the subject [Visual Analog Scale (VAS)] for each tooth tested. Hypersensitivity was assessed immediately post-treatment and at 2 months post-treatment. RESULTS: For the sodium fluoride varnish group, the mean Schiff score decreased 61% from baseline immediately post-treatment (P= 0.0006) and 41% at Month 2 (P= 0.0069). For the oxalic acid/potassium salt solution group, the mean Schiff score decreased 33% from baseline immediately post-treatment (P= 0.0305) and 29% at Month 2. Similarly, the mean VAS scores in the sodium fluoride varnish group decreased 41% from baseline immediately post-treatment (P= 0.0030) and 34% at Month 2 (P= 0.0275). The mean VAS scores in the oxalic acid/potassium salt solution group decreased 35% from baseline immediately post-treatment (P= 0.0168) and 33% at Month 2 (P= 0.0283). An analysis of covariance found no statistically significant between-group differences in mean Schiff scores or VAS scores immediately post-treatment or at Month 2. Both treatments were well tolerated. There were no reported adverse events in either treatment group. CLINICAL SIGNIFICANCE: Both 5% sodium fluoride varnish and an oxalic acid/potassium salt solution are safe and effective options to treat dentin sensitivity in otherwise healthy adults. The examiner-rated Schiff scores and the patient-rated VAS scores consistently demonstrated a reduction in sensitivity with either treatment, both immediately after professional application and at 2 months post-treatment.

Effect of instruction, light curing unit, and location in the mouth on the energy delivered to simulated restorations.

PURPOSE: To determine the amount of energy (Joules/cm²) delivered by students to simulated restorations in a patient simulator based on the restoration location, the curing light unit used, and before vs. after instruction on how to improve their light curing technique. METHODS: 30 dental students "light cured" two simulated restorations (that were 1-mm deep anterior and 4-mm deep posterior) using three light-curing units (LCUs) : VALO, Bluephase G2, and Optilux 401. A MARC Patient Simulator was used to measure the irradiance (mW/cm²) received by the restorations in real-time to calculate the radiant exposure (J/cm²) delivered during a 20-second exposure. At first, students were asked to use the light curing technique that they had been previously taught. They were then given 5 minutes of additional verbal instructions and a practical demonstration on proper curing technique using the patient simulator. They then light cured the restorations again. Based on a literature review, 16 J/cm² was considered the minimum acceptable radiant exposure. RESULTS: Before receiving instruction using the simulator, some students delivered as little as 4 J/cm² to the restoration. A mixed model test determined that the radiant exposure delivered to the anterior restoration was significantly greater than that delivered to the posterior restoration (Plt; 0.001). Additionally, when the locations were compared for each LCU individually, a paired t-test determined that before the students received the additional instruction, the anterior restoration received a significantly greater radiant exposure than the posterior restoration, for all three LCUs. Further paired t-tests and Wilcoxon signed-rank tests determined that after instruction, the radiant exposure improved significantly at both the anterior and posterior locations, for all three LCUs. The Bluephase G2 and the VALO each individually delivered 45% more radiant exposure than the Optilux 401 (P< 0.001 for both). The Bluephase G2 and VALO lights delivered similar mean radiant exposures (25.4 J/cm² and 25.7 J/cm², respectively). This difference was not significant. Depending on the light unit used, at the posterior location, there was a 24 to a 52% increase in the mean radiant exposure that was delivered after instruction compared to before instruction. CLINICAL SIGNIFICANCE: Prior to using the patient simulator, students and their instructors thought that the students were delivering an adequate amount of energy when light curing. This was not always the case. The location of the restoration, the curing light output, its size and shape and how it is used all affected the amount of energy delivered to a restoration. Dental professionals and educators should be aware that appropriate training can improve the amount of energy delivered, and that restorations in posterior teeth will require longer exposure times than those in anterior teeth.

Effects of surface treatments and cement types on the bond strength of porcelain-to-porcelain repair.

PURPOSE: The purpose of this in vitro study was to evaluate the effects of four surface treatments and two resin cements on the repair bond strength of a ceramic primer. MATERIALS AND METHODS: Eighty-eight pairs of disks (10 and 5 mm in diameter, 3 mm thickness) were prepared from heat-pressed feldspar ceramics (GC Initial IQ). After being stored in mucin-artificial saliva for 2 weeks, the 10-mm disks were divided into four surface treatment groups (n = 22) and then treated as follows: (1) no treatment (control); (2) 40% phosphoric acid; (3) 5% hydrofluoric acid + acid neutralizer + 40% phosphoric acid; (4) silica coating (CoJet-sand) + 40% phosphoric acid. The 5-mm disks were treated with 5% hydrofluoric acid + 40% phosphoric acid. The two sizes of porcelain disks, excluding the control group, were primed with Clearfil Ceramic Primer. The specimens in each group were further divided into two subgroups of 11 each, and bonded with Clearfil Esthetic Cement (CEC) or Panavia F 2.0 Cement (PFC). The specimens were stored in distilled water at 37°C for 24 hours, thermocycled for 3000 cycles at 5 to 55°C, and stored at 37°C for an additional 7 days. Shear bond strength (SBS) was measured with a universal testing machine at a 0.5 mm/min crosshead speed until fracture. Statistical analysis of the results was carried out with a two-way ANOVA and Tukey HSD test (α = 0.05). Debonded specimen surfaces were examined under an optical microscope to determine the mode of failure. RESULTS: The statistical analysis showed that the SBS was significantly affected by surface treatment and resin cement (p < 0.05). For treatment groups bonded with CEC, the SBS (MPa) values were (1) 2.64 ± 1.1, (2) 13.31 ± 3.6, (3) 18.88 ± 2.6, (4) 14.27 ± 2.7, while for treatment groups cemented with PFC, the SBS (MPa) values were (1) 3.04 ± 1.1, (2) 16.44 ± 3.3, (3) 20.52 ± 2.2, and (4) 16.24 ± 2.9. All control specimens exhibited adhesive failures, while mixed types of failures were observed in phosphoric acid-treated groups. The other groups revealed mainly cohesive and mixed failures. CONCLUSIONS: Combined surface treatment of etching with hydrofluoric acid and phosphoric acid provides the highest bond strengths to porcelain. Also, PFC exhibited higher SBS than CEC did.

Two-year evaluation indicates zirconia bridges acceptable alternative to PFMs.

OBJECTIVE: The aim of this in-vivo study was to evaluate the 2-year clinical performance of zirconia computer-aided design/computer-aided manufacturing (CAD/CAM)-generated bridges. METHODS: A total of 16 three- or four-unit Lava zirconia bridges were done on 15 subjects. The bridges were cemented using RelyX™ Unicem Self-Adhesive Universal Resin Cement. Evaluation was done at 6-month, 1-year, and 2-year recall visits. Evaluation criteria were color stability and matching, marginal integrity, marginal discoloration, incidence of caries, changes in restoration-tooth interface, changes in surface texture, postoperative sensitivity, maintenance of periodontal health, changes in proximal and opposing teeth, and maintenance of anatomic form. In each of these parameters, the bridges were rated in one of three possible categories: "A" (alpha)--ideal; "B" (bravo)--acceptable; and "C" (charlie)--unacceptable. RESULTS: After 2 years, 100% of the bridges were rated "A" for color stability and matching, marginal discoloration, incidence of caries, changes in restoration-tooth interface, changes in surface texture, postoperative sensitivity, and change in proximal or opposing teeth. In the parameter of marginal integrity, 6.25% of the bridges were rated "B;" the remaining 93.75% were rated "A." Maintenance of periodontal health was rated "B" for 6.25% of the bridges and "A" for 93.75%. At 2 years, 12.5% of the bridges rated "C" in maintenance of anatomic form and 87.5% rated "A." CONCLUSION: The overall clinical outcome was that the CAD/CAM-generated zirconia bridges were clinically acceptable.

Do bib clips pose a cross-contamination risk at the dental clinic?

Although multiple-use dental napkin holders have a relatively low risk of transmitting infection, they do require disinfection between patients. This study sought to: 1) determine the presence of bacterial load on two types of clips of reusable bib chains after dental procedures at the Endodontics and Orthodontics clinics at Tufts University School of Dental Medicine; and 2) evaluate the effectiveness of disinfecting the clips. These specialty clinics represent a wide spectrum of patients, procedures, and appointment times. Bacterial load on the bib clips was determined immediately following dental treatments-both before and after their disinfection-during morning and afternoon sessions. The results revealed that, after treatments, there was a statistically significant difference when comparing the two clinics for bacterial burden on the clips. Furthermore, there was a statistically significant difference in bacterial load on the two types of clips. Disinfection of the bib clips was highly effective in both clinics. Clinically, the results suggest that due to the nature of the treatment, the demographic population, and the type of bib clips used, patients in different clinics may be exposed to varying bacterial concentrations on the bib clips, and thus to different possible cross-contamination risks. Future analyses will be performed to identify the bacterial species in samples from both pre- and post-disinfected clips, and to determine if they harbor disease-causing bacterial species that can pose a potential, yet undetermined risk for cross-contamination.

Long-term use of 6.5% hydrogen peroxide bleaching strips on tetracycline stain: a clinical study.

UNLABELLED: This study evaluated the clinical response following extended daily use of a trayless 6.5% hydrogen peroxide (H2O2) tooth bleaching gel in patients with tetracycline stains. MATERIALS AND METHODS: In this clinical trial, participants (N = 30) were assigned to a strip product following screening for tetracycline staining. Subjects used the product for 6 months, with clinical safety and efficacy measurements assessed at the end of each month. The strips were used for 30 minutes twice daily (maxillary arch only). Treatment efficacy was determined by the tooth color change from baseline using an expanded VITA shade guide. Additional shades were added on either side, representing colors whiter than B1 and darker than C4. RESULTS: The strips averaged shade reduction in Months 1, 2, and 3 visits, respectively. Of all the subjects, 65% reached B1 color by Month 6. Treatment was generally well tolerated. Mild and transient tooth sensitivity (46.7%) and oral discomfort (43.3%) were the most common adverse events associated with daily bleaching, yet neither affected study participation. CONCLUSIONS: The 6.5% H2O2 bleaching strip provided significant tooth whitening in subjects with tetracycline stains. CLINICAL SIGNIFICANCE: When used daily for 6 months, a 6.5% H2O2 bleaching strip can be effective in whitening tetracycline stains. The professional strip was well tolerated throughout the 6-month period. This extended use provides additional evidence of clinical safety associated with the use of this product for vital bleaching.

Fears and concerns of individuals contemplating esthetic restorative dentistry.

Questionnaires that focus on the fear of dental treatment typically include a narrow list of previous treatment-related factors. By omitting items concerned with psychologic, emotional, and interpersonal traits that impact treatment, practitioners often fail to gain additional valuable information on related anxiety issues. This study was undertaken to identify previously unrecognized or poorly discussed sources of fear and anxiety in patients seeking esthetic dental treatment. The Esthetic Clinic at Tufts University School of Dental Medicine recruited 62 participants who were asked to score their level of anxieties and concerns based on 24 different items on a 0 to 5 Likert scale. In addition, age, gender, and type of procedure in consideration were the only other variables recorded. The item that elicited the highest level of anxiety was "not feeling happy with my new smile." Thirty-eight respondents (61.3%) said they feel "markedly anxious"or "severely anxious" or answered "avoid completely." Concerns "that the outcome might look false and unnatural" or "that the dentist might not redo it if I am not satisfied with the outcome" both received 37 out of 62 (59.7%) similar responses. These results suggest obstacles to treatment exist not only in areas typically investigated but also in factors rarely discussed during the patient-practitioner encounter. The practitioner needs to consider a broader range of issues when addressing the patient's concerns.

Placebo-controlled clinical trial of use of 10% hydrogen peroxide whitening strips for medication-induced xerostomia.

OBJECTIVE: A randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate the effectiveness and safety of peroxide-containing strip-based tooth whitening among subjects with medication-induced hyposalivation. METHODS: Eligibility for this tooth whitening study was limited to dentate adults taking xerogenic medications with an unstimulated salivary flow < or = 0.2 ml/min. After giving informed consent, 42 subjects were randomized using a 2:1 ratio to 10% hydrogen peroxide whitening strips (Crest Whitestrips Premium) or placebo strips without peroxide. Strips were used for 30 min twice daily for a 14-day period. Usage was unsupervised, and only the maxillary arch was treated. On days 8 and 15, efficacy was assessed from standard digital images of the anterior dentition and quantified using the Cielab color system, while safety was assessed from interviews and clinical examinations. RESULTS: At day 8, the peroxide group experienced significant (p < 0.001) color improvement relative to baseline and placebo. Adjusted means +/- standard errors for yellowness reduction were -1.65 +/- 0.115 units for the peroxide group and -0.32 +/- 0.170 units for the placebo group. For the increase in lightness, adjusted means +/- standard errors on day 8 were 1.53 +/- 0.130 units for the peroxide group and 0.37 +/- 0.191 units for the controls. Continued strip use through day 15 yielded incremental color improvement for the peroxide group. Mild and transient tooth sensitivity represented the most common adverse events. No subject discontinued treatment due to a product-related adverse event. CONCLUSION: Twice daily use of 10% hydrogen peroxide whitening strips by adults with medication-induced xerostomia was well tolerated, with significant tooth color improvement evident within 7 days.

Clinical trial assessing light enhancement of in-office tooth whitening.

OBJECTIVE: Evaluate a light-enhanced in-office tooth whitening system in order to assess tooth color and safety. METHODS: Thirty-three adults were randomly assigned to one of three treatment groups. Professional treatment involved application of a 25% H(2)O(2) gel (Discus Dental ZOOM!) with light enhancement, H(2)O(2) gel alone, or the light alone with no peroxide. The 12 anterior teeth were treated three times for 20 minutes each. Efficacy was measured objectively as L*a*b* color change using digital images, tooth shade was measured, and safety was evaluated immediately after treatment and at posttreatment days 7 and 30. RESULTS: After adjusting for baseline and age, immediate (end-of-treatment) means (SE) for Deltab* (yellowness) were -3.1 (0.25) for the gel + light, -2.0 (0.25) for the gel-only group, and -2.4 (0.25) for the light-only group. Significant (p < 0.05) color rebound was evident at posttreatment day 7. By day 30, adjusted means (SE)for Deltab* were -1.7 (0.20) for the gel + light group, -1.1 (0.20) for the gel-only group, and -0.5 (0.20) for the light-only group. Both peroxide groups differed significantly (p < 0.05) from light alone on Deltab* and DeltaL*. In the gel + light group, 91% of subjects experienced tooth sensitivity, the majority of which was moderate or severe. Adverse events were low in the light-only group. CONCLUSION: Use of light enhancement for in-office whitening leads to immediate color change, after which there was significant color and shade rebound within 7 days as well as moderate-to-severe tooth sensitivity during and after treatment. CLINICAL SIGNIFICANCE Increased tooth sensitivity during treatment and appreciable short-term color rebound after treatment may impact the utility of in-office tooth whitening with peroxide and light as a stand-alone esthetic procedure. (J Esthet Restor Dent 21:336-347, 2009).

Treatment modalities for caries management, including a new resin infiltration system.

Seemingly against all odds, dental caries still affects most people in the US. While fluoridated products, school-based screening and cleaning programs, better patient education, and professional and chemotherapeutic interventions have all impacted certain populations, caries is still the most prevalent chronic childhood disease and continues to affect a high percentage of adolescents, young and middle-aged adults, and seniors. Much research has proven that dental caries is not just an occasional cycle of cavitation but a complex and infectious disease process. Historically, addressing the caries challenge has relied on prevention and restoration, with no intermediary means to stop lesion progression. Recently, a technique called caries infiltration was introduced that fills the noncavitated pores of an incipient lesion with a low-viscosity resin by capillary action, creating a barrier that blocks further bacterial diffusion and lesion development. This microinvasive method for stabilizing early lesions requires no drilling or anesthesia and does not alter the tooth's anatomic shape. In cases of white spot lesions in the esthetic zone, it also eliminates opaqueness and blends with surrounding natural teeth. This article presents an overview of caries prevention initiatives and a case demonstrating the new caries infiltration technique. Combined with shifting the focus to caries risk assessment, this promising technology may prove to be a significant addition to the profession's caries treatment armamentarium.

Jumpstart Mirror Trainer: A New Device for Teaching Mirror Skills to First-Year Dental Students.

Learning indirect vision with a dental mirror is challenging and can be overwhelming for beginning dental students. The Jumpstart Mirror Trainer is a new device that allows students to become proficient with mirror use before the start of preclinic without requiring in-class practice sessions. The aim of this study, conducted in 2017, was to compare the effectiveness of the Jumpstart Mirror Trainer with the Mirroprep for teaching indirect motor skills. Forty-seven first-year dental students were randomized into three groups to use the Jumpstart Mirror Trainer, Mirroprep, or a control device for 15 minutes a day for ten days. To assess indirect motor skills improvement, students performed a maxillary cavity preparation before and after using their devices. A survey was used to assess students' comfort level with mirror skills and perceived helpfulness of the exercises. Forty students completed the study. The Jumpstart Mirror Trainer activities improved the students' scores significantly more than the Mirroprep activities (p=0.04) and the control device (p=0.006). Students in the Jumpstart Mirror Trainer group rated their device as being significantly more helpful than the control group rated its device in preparing them for the evaluation (p=0.001). There was no statistically significant difference in perceived helpfulness between the Mirroprep group and the control group (p=0.75). These results suggest that the Jumpstart Mirror Trainer may be able to improve students' indirect motor skills without requiring in-class practice sessions and to do so more effectively than other existing methods.

Separate whitening effects on enamel and dentin after fourteen days.

The purpose of this study was to investigate the mechanism of action of a bleaching agent, as it relates to enamel and dentin. Twenty-six extracted human molar teeth were sectioned at the cemento-enamel junction and were randomly assigned to two groups. L*a*b* readings were taken with a spectrophotometer: on buccal surfaces of the crown, at enamel and dentin. The teeth were exposed to carbamide peroxide or placebo gel and L*a*b* scores were again recorded to determine color changes. Treatments were compared using ancova test with baseline color as the covariate. Relative to placebo, buccal surfaces exhibited the greatest Deltab* and DeltaL* color change. On buccal surfaces, the adjusted mean (SE) treatment differences were -7.8 (1.00) for Deltab* and 5.7 (0.97) for DeltaL, with groups differing significantly (p < 0.0001). On enamel surfaces, treatment differences were -3.6 (0.61) for Deltab* and 4.6 (0.80) for DeltaL* (p < 0.0001). Dentin exhibited the least color improvement. Adjusted mean (SE) treatment differences were -1.9 (0.87) for Deltab* and 2.4 (1.10) for DeltaL*, with groups differing significantly (p < 0.02) on dentin color change. The majority of color change seen on the buccal surface of tooth crowns exposed to carbamide peroxide 15% was because of the color change in enamel. As compared to enamel, dentin was less affected after 14 days.

Daytime use of a custom bleaching tray or whitening strips: initial and sustained color improvement.

PURPOSE: To compare the clinical response of 6% hydrogen peroxide whitening strips and a 10% carbamide peroxide custom tray system under common daytime usage conditions, in an Italian dental research center. METHODS: Informed consent and baseline measurements were collected, and 43 healthy adults were randomly assigned to 6% hydrogen peroxide whitening strips (Crest Whitestrips) or the 10% carbamide peroxide custom tray (Opalescence 10%). The maxillary arch was treated twice daily for 30 minutes at-home. Treatment was discontinued after 2 weeks, and subjects were monitored for an additional 4 weeks. Efficacy (initial and sustained) was measured objectively from standard digital images of the maxillary facial tooth surfaces using the international CIELAB system. Safety was assessed from interview and examination. Treatments were compared after 2 weeks (end-of-treatment) and 6 weeks (4 weeks post-treatment) using analysis of covariance methods. RESULTS: Both groups exhibited color improvement at the Week 2 end-of-treatment visit. For yellowness, mean (SD) Deltab* at Week 2 was -2.10 (0.70) for the strip group and -1.61 (1.03) for the tray group. For lightness, mean (SD) DeltaL* at Week 2 was 1.25 (0.92) for the strip group and 1.17 (1.19) for the tray group. Compared to Week 2, the strip group retained 89-92% of the initial Deltab* and DeltaL* color improvement at Week 6 (4 weeks post-treatment), while the tray group had 80-90%. Groups differed significantly (P< 0.05) on end-of-treatment and post-treatment Deltab*, favoring the strips. Both daytime treatments were well-tolerated, with minor tooth sensitivity and oral irritation representing the most common findings.

Effects of an in-office bleaching system (ZOOM) on pulp chamber temperature in vitro.

AIM: Several new techniques and materials for in-office bleaching have been introduced recently. The aim of this in vitro study was to measure the temperature increase in the pulp chamber of extracted teeth produced by the Zoom! in-office bleaching system and to investigate the influence of this light in conjunction with the bleaching gel on pulp temperature rise. METHODS AND MATERIALS: Ten extracted, caries-free, unrestored human maxillary central incisor teeth were used for the study. The root of each tooth was cut approximately 2-3 mm apical to the cementoenamel junction (CEJ), and the apical orifice of the root canal was enlarged. The remaining pulp tissue was removed and the empty pulp chamber was filled with a heat sink compound. A thin K-type thermocouple was inserted into the pulp chamber through the cut root area. The root surfaces of the teeth were partially submerged in a water bath during the testing procedure at 37 degrees C. A whitening gel containing 25% hydrogen peroxide was applied to the buccal surfaces of all ten teeth and exposed to a Zoom! activation light for twenty minutes for three times; this was designated as Group I. The same teeth were then exposed with the Zoom! light for the same time period without the application of the bleaching gel and designated as Group II. The intrapulpal temperature pre-treatment (baseline) and the temperature increase during treatment was measured for both treatment groups. RESULTS: There was a statistically significant difference between the two groups (p=0.003). Application of the Zoom! light in conjuction with the application of bleaching gel produced a greater temperature rise than did the light alone. The mean temperature rise for Group I (light and bleaching gel) was 1.11 degrees C (0.18 degrees C) and 1.01 degrees C (0.12 degrees C) for Group II (light alone) at the end of a five-minute exposure. CONCLUSION: The Zoom! light either used with or without bleaching gel showed no significant increase in the intrapulpal temperature of teeth when used for the recommended exposure time.

The Knoop hardness of a composite resin polymerized with different curing lights and different modes.

AIM: The purpose of this study was to compare the surface hardness of a hybrid composite resin polymerized with different curing lights. METHODS AND MATERIALS: Two 3.0 mm thick composite resin discs were polymerized in a prepared natural tooth mold using: (1) a conventional quartz-tungsten halogen light (QTH- Spectrum 800); (2) a high-intensity halogen light, Elipar Trilight (TL)-standard/exponential mode; (3) a high-intensity halogen light, Elipar Highlight (HL)-standard/soft-start mode; (4) a light-emitting diode, Elipar Freelight (LED); and (5) a plasma-arc curing light, Virtuoso (PAC). Exposure times were 40 seconds for the halogen and LED lights, and three and five seconds for the PAC light. Following polymerization, the Knoop hardness was measured at the bottom and the top surfaces of the discs. RESULTS: Significant differences were found between top and bottom Knoop Hardness number (KHN) values for all lights. The hardness of the top and bottom surfaces of both specimens cured by the PAC light was significantly lower than the other lights. No significant hardness differences were observed between the remaining curing units at the top of the 2.0 mm specimens. Significant differences were found between the LED and two modes of HL on the bottom surfaces. For the 3.0 mm thick samples, while significant differences were noted between LED and TL standard mode and between the two TL curing modes on the top, significant differences were only observed between QTH and the standard modes of TL and HL at the bottom.